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https://pos.sissa.it/374/054/	Volume 374 - Light Cone 2019 - QCD on the light cone: from hadrons to heavy ions (LC2019) - Contributed Boson Stars and QCD Boson Stars U. Kulshreshtha,* S. Kumar", D.S. Kulshreshtha", J. Kunz" *corresponding author Full text: pdf Pre-published on: May 06, 2020 Published on: May 26, 2020 Abstract In this talk, we present a review of our work on boson stars in a theory of a massless complex scalar field in the presence of a $U(1)$ gauge field and gravity. A sequence of bifurcation points obtained in the phase diagrams of the theory is presented and the plots of the mass $~M~$ versus charge $~Q~$ as well as plots of the mass per unit charge $~M/Q~$ versus the charge $~Q~$ of the boson stars are presented along with a discussion of the results. We also present some ideas on the possibilities of QCD boson stars. DOI: https://doi.org/10.22323/1.374.0054 How to cite Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete. Open Access	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8848193287849426, "perplexity": 1360.3474519449649}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623488552937.93/warc/CC-MAIN-20210624075940-20210624105940-00278.warc.gz"}
http://www.sciforums.com/threads/do-heavier-objects-fall-faster.39234/page-2	Do heavier objects fall faster? Discussion in 'Physics & Math' started by mountainhare, Aug 2, 2004. 1. Brandon9000Registered Senior Member Messages: 172 Aside from air resistance, all objects near the surface of the earth fall at an acceleration of: GM/r^2 Where G is the gravitational constant, M is the mass of the Earth, and r is the distance between the falling object and the center of the Earth. This is approximately 9.8 meters per second squared, and it is the same for all objects, regardless of their mass. 3. J_WilsonRegistered Member Messages: 4 That is not right Brandon. There is an equation that looks something like that to give you force. f=ma so the acceleration is f/m. We've already established this. 5. Brandon9000Registered Senior Member Messages: 172 A = F/m where F, m, and A refer to the falling object. F = (GMm)/r^2 where M = mass of Earth and m = mass of the falling object. Plugging the 2nd equation into the first, which is equivalent to dividing the 2nd by m, gives, A = GM/r^2, as in my original post, regardless of the mass of the falling object. This particular acceleration is called "the acceleration due to gravity." Note that the only mass which appears in this equation is the mass of the Earth. Incidentally, you can find this material in virtually every high school Physics book in the world. 7. Blue_UKDrifting MindValued Senior Member Messages: 1,446 Brandon, check one of my above posts (lots of colour) - we all agree that objects accel towards earth at the same rate, it's the earth's accel towards the object that changes! 8. Brandon9000Registered Senior Member Messages: 172 This is so, but the acceleration of the Earth toward the object is infinitessimal. Someone may find this interesting theoretically, but the Earth's acceleration is so tiny as to be of no practical significance. The force exerted on the Earth by the object is identical to the force exerted on the object by the Earth, but the Earth has incomparably greater mass. 9. Blue_UKDrifting MindValued Senior Member Messages: 1,446 I agree. Needless to say I am more interested in the actual physics than the practical observation. 10. newbie56kRegistered Member Messages: 25 What r u guys doing, the ratio of force to mass is the same for large and small objects. Force = mass x acceleration (force is equal to acceleration, w=ma [same thing]) 98N Force --------- = 9.8m/s/s 10kg Mass 4900N Force ----------- =9.8m/s/s 500Kg Mass See the acceleration is the same, for large and small. I got most of this from my midterm exam notes for physics and i got a 103% in it. People think that heavier objects fall faster because it hurts much more when it lands on their foot. 11. curioucityUnbelievable and oddRegistered Senior Member Messages: 2,429 The problem of roughly mixing force and pressure, and density too, maybe... 12. MacMRegistered Senior Member Messages: 10,104 You need to be careful in what you stipulate. Falling faster meaning F=ma of a free falling object, it is correct to say they all fall at the same rate. However, even getting that 103% on your mid-term fails to acknowledge that the earth indeed also moves toward the object and does so to a greater extent for a more massive object such that the closure rate and contact with the earth from an initial height (in theory) actually contacts earth sooner because the earth moved more toward the heavier object. I refer you to "Blue UK's" post on 8/3/04 at 6:58 AM above. He shows you mathematically why this is the reality (even though it is immeasureable). 13. vslayerRegistered Senior Member Messages: 4,969 the objects are both being pulled by the same amount of force(gravity) so the only factor to slow them down is wind resistance, if you dropped a ten ton weight and a parachute in a vacuum they would land at the same time. tho only extro factor is the force on imparct, in which case you would multiply the mass by the amount of gravity. in coclusion: during a freefall with no resistance, the force of all objects are equal, it is only when they land that their mass or surface area becomes a factor 14. MacMRegistered Senior Member Messages: 10,104 I normally tend to agree with you on things but here you have made some errors. 1 - Free falling objects do NOT all have the same force. i.e. - a 1 gram ball falls under a 1 gram force. A 10 kg ball falls under a 10 kg force. That is the meaning of the equivelence principle between inertia and gravity. Since objects acclerate by amounts of force which are always equal to the mass the rate of acceleration is the same but not the accelerating force. 2 - However it can be seen that objects only contact the earth at the same time in such tests if the test is conducted simultaneously. And in that case both objects contact the earth sooner than if either had been tested independantly. 3 - Since the force on the object is 1 gram or 10 kg causing their acceleration, the complimentary force on earth must be equal. It is obvious that if you apply a series of forces to earth with a 10,000/1 ratio of magnitude you are going to get an acceleration of the earth toward the objects which have a 10,000/1 magnitude. That is to say the earth moves 10,000 times as far toward the free-falling object which has the 10 kg mass. Since the earths motion in response to free-falling objects is different in each case the closure rate and contact of the free falling object with earth MUST change and the time is not the same. 15. vslayerRegistered Senior Member Messages: 4,969 but lets say the earths gravity has a power of 10 the earth can only pull things at a speed of 10 because that is all its power allows no matter how much an object weighs it can only ever go as fast as 10 the only thing to make a light object fall slower is the fact that it cannot displace as much air as a heavier object in a vacuum both objects would be pulled at a speed of 10, and since they do not need to displace any other particles there is nothing to give the heavier one an advantage 16. MacMRegistered Senior Member Messages: 10,104 What you are missing is this: (Air resistance ignored). If filmed against a scaled backdrop (i.e. - a tape measure and a clock) where the tape hangs from a point in space above earth (not attached to earth) and a light and heavy object are dropped individually, you could then see that each crossed markings of the tape at identical times. But what you miss is that while these objects are in free-fall the earth is either moving (F=ma) toward theses objects with a force that is either heavy or light. Clearly the earth during such free-fall time will move more under the influence of the force from the heavy object. Hence the heavy object ultimately travels less distance before contacting the earth because the earth move closure to it that it did when the lighter oject was free-falling. Because the havy object must travel less distance (at the same speeds and acceleration) as the lighter object it requires less time for free-fall to contact with earth. Now if we make the scale a solid ruler mounted to earth one would see the collective closure rate between earth and the free-falling objects and low and behold we would see that heavy objects were falling faster in such a test. 17. Paul TRegistered Senior Member Messages: 460 MacM, I would say those are BS. Say those two objects were let to fall at the same time. Let ignore other falling objects, consider just those two objects and also, of course, assume that earth movement toward those objects is signaficant at all. Shouldn't the earth accelerate toward the falling object at one certain rate (not difference rate for each falling object)? Force resultant to earth is due to both of the falling object. You can't expect earth to move at one accelleration rate to object A and another to object B, while A and B move side by side at the same acceleration. 18. PeteIt's not rocket surgeryRegistered Senior Member Messages: 10,166 Hi Paul, A larger mass requires greater force than a smaller mass to accelerate at the same rate. If A and B are of different masses, but experience the same acceleration, then they must be subject to different forces. This means that the Earth also experiences greater force when the larger mass object is falling. A few notes: Objects falling side-by-side is a different problem. Since they are falling together, the Earth is moving toward both. You also need to consider the attraction between the objects... The problem changes again depending on exactly how far away from each other are the two objects falling at the same time... The problem changes again if you consider the direction of separation between the objects, as any North-South separation will involve Coriolis forces, and attraction between the objects will have curious effects on East-West separation... When considering the objects' effect on the Earth, you should also consider tidal effects. The near part of the Earth is attracted much more strongly than the far part, so the Earth will be stretched. This means that the Earth's material properties (bulk modulus etc) will need to be considered... Further complicated by differences in material properties throughout the Earth... Of course, all these problems are insignificant beside local variations in gravity. For reasonably sized objects, such things as random air mass movements (ie weather) will have more effect on the fall rate than any of the above mentioned issues. 19. Paul TRegistered Senior Member Messages: 460 Hi Pete This is certainly okay to me. This was exactly the case mentioned by MacM. Therefore, earth should accelerate to both object at one rate only. Even if the film was taken one at a time for object A and B, which has different mass, there is one thing remain the same...the system center of mass. If we don't consider the variation of gravitational acceleration due to the change of distance, the acceleration of object A and B relative to the system center of mass is not affected by the rate of earth acceleration toward the object (or the system center of mass). Therefore, I didn't see MacM's idea indicating that somehow heavier object fall faster. He just picked the wrong reference point. I think we can put a side all those issues for the time being. 20. MacMRegistered Senior Member Messages: 10,104 1 - First you must understand that the affect only occurs if the objects are dropped independantly at different times. 2 - The mass of Earth is 5.9742E24Kg 3 - If dropped independantly a 1 gram mass places a 1 gram force on earth during free-fall. F = ma, a = F/m: a = 0.001kg/5.9742kg = 1.6738E-28 4 - If you now drop a 10kg mass during free fall it generates a force on Earth of 10kg: a = 10kg/5.9742E24kg = 1.6738E-24 The acceleration by the earth (however miniscule) during a free-fall period of a mass is 10,000 times greater for a mass 10,000 times as large. The acceleration of the free-falling masses is always the same because the accelerating force equals the inertial mass. 5 - Dropped simultaneously the collective mass in free-fall is 10.001kg and induces a force of 10.001kg on the Earth : a = F/m = 10.001kg/5.9742E24kg = 1.6740E-24 In this case both objects contact the earth at the same time but the total time is less than if either are dropped independantly. The point that people seem to be missing is that this is "Closure Rate" from point of free-fall to contact. The velocity of free-falling objects relative to the point of initial release is always the same but the velocity relative to earth varies because earth also moves (at differnt rates) towards the free-falling objects. The magnitude of motion during free-fall is inversly proportional to the masses involved. That is the total distance moved is divided between the Earth and the object in proportion to their masses. If a 10kg object is placed 16 feet (using rounded generic numbers here) above earth, due to the formula used we expect it to travel 16 feet in one second and make contact but the reality is that it only free-falls for 1 second minus the 1.6738E-24 acceleration time reduced because Earth moved in response to the 10kg force. For the 1 gm object it free-falls for 1 second minus 1.6738E-28 acceleration time. You can see that the reality is that the closure rate is less for heavier objects, even though it is true that the acceleration of the object and its terminal velocity relative to its free-fall origin are the same for either mass. The impact velocity with Earth however is greater and the time period of the free-fall is less because Earth acclerates, hence moves greater distance towqrd heavier objects and attains a greater velocity during the free-fall. 21. MacMRegistered Senior Member Messages: 10,104 You have clearly mis-read my post. I stated objects falling simultaneously will contact Earth at the same time but that that time will be less than if they were dropped indenpendantly at different times. Not at all. You are picking a different reference point than is used in the F = G * m1 * m2 / r^2 and F = ma formulas. See my previous response to your post to me above. The "Closure Rate" (time of free-fall) is less for heavier objects. 22. Paul TRegistered Senior Member Messages: 460 Okay. Let's go with that situation. This is a meaningless argument with respect to "Do heavier object fall faster?" Your argument doesn't prove anything. It's like: At one time, you walk slowly toward a car accelerating toward you at rate 9.81m/s<sup>2</sup>, then at other time you run toward that car and you argued that when you run, the car closure rate is higher -- equivalent to having higher acceleration. This argument has not much value as it prove nothing about whether the car acceleration increase because you are running (the car acceleration, of course, not affected by your running!). You just picked an incorrect reference point to assess the problem. Your argument, as I said tell us nothing about whether heavier object fall faster or not...hence, it's a pointless argument. 23. MacMRegistered Senior Member Messages: 10,104 Not at all. I clearly pointed out the arguement; including the fact that from the reference point of the start of free fall the acceleration and velocity of all objects are the same. I also pointed out the FACT that the time to impact with the earth IS NOT THE SAME. Should you actually set up a test capable of measuring this insignifigant difference you will find that due to the variable closure rate your test will yield results which show that the heavier objects impact the earth sooner. I didn't pick an incorrect reference point I am simply showing that it is only one view and that a timed free-fall over an equal distance is less for the heavier object. Your test being referenced from earth will result in a velocity calculation which is higher. The momentum of impact if you measure it at the earth's surface will be greater. Remember, all velocity is relative. If earth is the rest reference for the test (which it generally and normally is), then you stand corrected. 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http://www.ipm.ac.ir/ViewPaperInfo.jsp?PTID=12368&school=Particles	## “School of Particles” Back to Papers Home Back to Papers of School of Particles Paper IPM / Particles / 12368 School of Particles and Accelerator Title: Combined results of searches for the standard model Higgs boson in pp collisions at sqrt(s) = 7 TeV Author(s): 1 Hessamadin Arfaei 2 Hamed Bakhshiansohi 3 Seyed Mohsen Etesami 4 Ali Fahim 5 Majid Hashemi 6 Hoda Hesari 7 Abideh Jafari 8 Mohsen Khakzad 9 A Mohammadi 10 Mojtaba Mohammadi Najafabadi 11 Saeid Paktinat 12 Batool Safarzadeh 13 Maryam Zeinali Status: Published Journal: Phys. Lett. B Vol.: 710 Year: 2012 Pages: 26-48 Supported by: IPM Abstract: Combined results are reported from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s)=7 TeV in five Higgs boson decay modes: gamma pair, b-quark pair, tau lepton pair, W pair, and Z pair. The explored Higgs boson mass range is 110-600 GeV. The analysed data correspond to an integrated luminosity of 4.6-4.8 inverse femtobarns. The expected excluded mass range in the absence of the standard model Higgs boson is 118-543 GeV at 95	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9830037355422974, "perplexity": 19581.321770352784}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323585186.33/warc/CC-MAIN-20211018000838-20211018030838-00265.warc.gz"}
https://zbmath.org/?q=an%3A0739.11042	× ## Ramanujan’s “Lost” Notebook. VII: The sixth order mock theta functions.(English)Zbl 0739.11042 The authors prove 11 identities from Ramanujan’s lost notebook. These involve seven functions defined by $$q$$-series, which are called mock theta functions. Let \begin{aligned} (x)_ n &=(x;q)_ n =\begin{cases} \prod_{i=0}^{n-1}(1-q^ ix), &n\geq 0,\\ \prod_{i=1}^{-n}(1- q^{-i}x)^{-1}, &n<0,\;x\neq q,q^ 2,\dots\hbox{ or } q^{-n}, \end{cases} \\ (x)_ \infty &=(x;q)_ \infty=\prod_{i\geq 0}(1-q^ i x), \hbox{ where } \| q\| <1, \\ \phi(q) &=\sum_{n\geq 0} {(- 1)^ n q^{n^ 2}(q;q^ 2)_ n \over (-q)_{2n}}, \\ \psi(q) &=\sum_{n\geq 0} {(-1^ n)q^{(n+1)^ 2}(q;q^ 2)_ n \over (- q)_{2n+1}}, \\ j(x,q)&=\sum_ n(-1)^ nq^{\left({x \atop 2}\right)}x^ n, \quad \| q\|<1. \\ \end{aligned} Two of the identities are \begin{aligned} \phi(q^ 9)-\psi(q)-q^{-3}\psi(q^ 9) &={{j(- q^ 3,q^{12})(q^ 6;q^ 6)^ 2_ \infty} \over {j(-q,q^ 4)j(- q^ 9,q^{36})}}, \\ {\psi(\omega q)-\psi(\omega^ 2 q)\over (\omega- \omega^ 2)q} &= {{j(-q,q^ 4)j(-q^ 9,q^{36})(q^ 3;q^ 6)_ \infty} \over {j(-q^ 3,q^{12})}} \\ \end{aligned} where $$\omega$$ is a primitive cubic root of 1. Results concerning $$\Theta$$ functions are proved first. Bailey pair method and constant term method are described next. These are used to derive Hecke type identities for the sixth order mock theta functions. The asymptotics of the functions for $$q$$ near a root of unity are also discussed. Reviewer: M.Cheema (Tucson) ### MSC: 11P82 Analytic theory of partitions 11F03 Modular and automorphic functions 05A30 $$q$$-calculus and related topics Full Text: ### References: [1] Andrews, G. E., The theory of partitions, (Rota, G.-C, Encyclopedia of Mathematics and Its Applications, Vol. 2 (1976), Addison-Wesley: Addison-Wesley Reading, MA) · Zbl 0155.09302 [2] Andrews, G. E., Hecke modular forms and the Kac-Peterson identities, Trans. Amer. Math. Soc., 283, 451-458 (1984) · Zbl 0545.10016 [3] Andrews, G. E., Multiple series Rogers-Ramanujan type identities, Pacific J. Math., 114, 267-283 (1984) · Zbl 0547.10012 [4] Andrews, G. E., Combinatorics and Ramanujan’s “lost” notebook, (Anderson, I., Surveys in Combinatorics 1985. Surveys in Combinatorics 1985, London Math. Soc. Lecture Note Series, Vol. 103 (1985), Cambridge Univ. Press: Cambridge Univ. Press London), 1-23 · Zbl 0575.05004 [5] Andrews, G. E., $$q$$-series: Their development and application in analysis, number theory, combinatorics, physics, and computer algebra, (Regional Conference Series in Mathematics, Vol. 66 (1986), Amer. Math. Soc: Amer. Math. Soc Providence, RI) · Zbl 0594.33001 [6] Andrews, G. E., The fifth and seventh order mock theta functions, Trans. Amer. Math. Soc., 293, 113-134 (1986) · Zbl 0593.10018 [7] Andrews, G. E., Ramanujan’s fifth order mock theta functions as constant terms, (Ramanujan Revisited: Proceedings of the Centenary Conference. Ramanujan Revisited: Proceedings of the Centenary Conference, University of Illinois at Urbana-Champaign, June 1-5, 1987 (1988), Academic Press: Academic Press San Diego) · Zbl 0646.10018 [8] Bailey, W. N., Generalized Hypergeometric Series, (Cambridge Tracts in Mathematics and Mathematical Physics, Vol. 32 (1964), Stechert-Hafner Service Agency: Stechert-Hafner Service Agency New York) · Zbl 0011.02303 [9] Bailey, W. N., On the basic bilateral hypergeometric series $$_2ψ_2$$, Quart. J. Math. Oxford Ser., 1, 2, 194-198 (1950) · Zbl 0038.05001 [10] Carlitz, L.; Subbarao, M. V., A simple proof of the quintuple product identity, (Proc. Amer. Math. Soc., 32 (1972)), 42-44 · Zbl 0234.05005 [11] Hickerson, D., A proof of the mock theta conjectures, Invent. Math., 94, 639-660 (1988) · Zbl 0661.10059 [12] Hickerson, D., On the seventh order mock theta functions, Invent. Math., 94, 661-677 (1988) · Zbl 0661.10060 [13] Hardy, G. H.; Wright, E. M., An Introduction to the Theory of Numbers (1968), Oxford Univ. Press: Oxford Univ. Press London · Zbl 0020.29201 [14] Ramanujan, S., (Hardy, G. H.; Aiyar, P. V.Seshu; Wilson, B. M., Collected Papers (1927), Cambridge Univ. Press: Cambridge Univ. Press London) · JFM 53.0030.02 [15] Ramanujan, S., The Lost Notebook and Other Unpublished Papers (1988), Narosa Publishing House: Narosa Publishing House New Delhi · Zbl 0639.01023 [16] Selberg, A., Über. die Mock-Thetafunktionen siebenter Ordnung, Arch. Math. Naturvidenskab, 41, 3-15 (1938) · JFM 64.1091.03 [17] Watson, G. N., The final problem: An account of the mock theta functions, J. London Math. Soc., 11, 55-80 (1936) · Zbl 0013.11502 [18] Watson, G. N., The mock theta functions (2), Proc. London Math. Soc., 42, 2, 274-304 (1937) · Zbl 0015.30402 This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9912741184234619, "perplexity": 6134.597183265926}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030335504.22/warc/CC-MAIN-20220930181143-20220930211143-00385.warc.gz"}
https://math.stackexchange.com/questions/1575396/linear-programming-problem-with-odd-objective-function	# Linear Programming Problem with odd objective function I have the linear problem as it follows. I have 3 different types of devices. Type A, Type B, Type C. At any given moment, there is exactly one type of each device installed. So one device A, one device B and one device C. Each type of device has its own probability to get damaged, so I want to have spare devices if these get damaged, with some constraints. Given the constraints, the objective function is to find the optimal number of devices of each type so that the probability for them to get damaged all at the same time is minimized. So we are looking for probability that A, B and C will get damaged at the same time, and we want to minimize it by having spare devices for each type. Probability that type A will get damaged: 0.3 Probability that type B will get damaged: 0.2 Probability that type C will get damaged: 0.4 Let x = number of devices A Let y = number of devices B Let z = number of devices C Those are the constraints: 10x + 15y + 8z <= 150 30x + 40y + 20z <= 400 15000x + 17000y + 13000z <= 200000 If I am not mistaking, the objective function should look like this. min P = (prob_damaged_A * x) * (prob_damaged_B * y) * (prob_damaged_C * y) min P = (0.3x) * (0.2y) * (0.8z) Is it OK if I transform that with natural logarithm into this? min P' = log[0.3x * 0.2y * 0.8z] min P' = xlog(0.3) + ylog(0.2) + z*log(0.8) min P' = -1.20397x - 1.60944y - 0.91629z I am not sure since all the signs have changed from positive to negatives, and the coefficients that were largest are now the smallest. For instance, z had its coefficient 0.4 which was the greatest, and now it is the smallest by absolute value: -0.916. Will the values of x, y, z be correct? Also, since I am looking for the number of devices of each type, i cant have fractions or irrational numbers as solution. Is there a way I can make a constraint that x, y, z must be integers? I suspect this should be: $$\min P = P_{A}^x \times P_{B}^y \times P_{C}^z$$ Or $$\min \log(P) = x \log(P_A) + y \log(P_B) + z \log(P_C)$$ The integer restrictions on $x,y,z$ can be added when you use a mixed-integer programming solver. E.g.:	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5636398792266846, "perplexity": 799.8148972142716}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579251681625.83/warc/CC-MAIN-20200125222506-20200126012506-00497.warc.gz"}
http://www.cs.cmu.edu/~dfox/abstracts/selection-aaai98.abstract.html	D. Fox, W. Burgard, S. Thrun, and A.B. Cremers Position Estimation for Mobile Robots in Dynamic Environments Proc. of the Fifteenth National Conference on Artificial Intelligence (AAAI-98) ### Abstract For mobile robots to be successful, they have to navigate safely in populated and dynamic environments. While recent research has led to a variety of localization methods that can track robots well in {\em static} environments, we still lack methods that can robustly localize mobile robots in dynamic environments, where, for example, people may block the robot's sensors for extensive periods of time. This paper proposes a family of probabilistic algorithms that can localize mobile robots even in densely populated environments. These algorithms are based on Markov localization, which estimates the location of a robot probabilistically. A novel entropy-based filter is employed for determining the "believability" of a sensor reading, thereby filtering out sensor readings that are corrupted by humans or unexpected changes in the environment. The technique was recently implemented and applied as part of an installation, in which a mobile robot gave interactive tours to visitors of the Deutsches Museum Bonn.'' Extensive empirical tests involving datasets recorded during peak traffic hours in the museum demonstrate that this approach is able to accurately estimate the robot's position in more than 99\% of the cases even in such highly dynamic environments. Full paper [.ps.gz] (1046 kb, 6 pages) Bibtex @INPROCEEDINGS{Fox98Pos, AUTHOR = {Fox, D. and Burgard, W. and Thrun, S. and Cremers, A.B.}, TITLE = {Position Estimation for Mobile Robots in Dynamic Environments}, YEAR = {1998}, BOOKTITLE = {Proc.~of the National Conference on Artificial Intelligence} } [Back to my research] [Back to my list of publications]	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.21703971922397614, "perplexity": 2510.4415059574535}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1405997894473.81/warc/CC-MAIN-20140722025814-00015-ip-10-33-131-23.ec2.internal.warc.gz"}
https://chemistry.stackexchange.com/questions/107027/dependence-of-rates-of-neighbouring-group-participation-on-length-of-alkyl-chain	Dependence of rates of neighbouring group participation on length of alkyl chain On the topic on neigbouring group participation, it is mentioned in Carey & Sundberg (2007)[1] that the effectiveness of the participation is dependent on on the ease with which the molecular geometry required for the participation can be attained. The example of the cyclization of ω-hydroxyalkyl halides was then given: The rate of cyclization of ω-hydroxyalkyl halides, for example, shows a strong dependence on the length of the chain separating the two groups. To prove the point, they showed the data for the solvolysis rates for ω-chloro alcohols with various chain lengths. Clearly, when a 5-membered ring is form, the rate of reaction is fastest. This is reasoned with the fact that a 5-membered ring has relatively little ring strain and thus, the rate of forming it would be relatively higher. However, this analysis does not seem to be convincing. If this reasoning was indeed correct, then wouldn't the next member in the series, with the capability of forming the 6-membered ring, have a higher solvolysis rate? $$\begin{array}{\|c\|c\|c\|c\|} \hline \text{Substrate} & k_\mathrm{rel}{}^\text{[2,3]} \\ \hline \ce{Cl(CH2)2OH} & 2000 \\ \hline \ce{Cl(CH2)3OH} & 1 \\ \hline \ce{Cl(CH2)4OH} & 5700 \\ \hline \ce{Cl(CH2)5OH} & 20 \\ \hline \end{array}$$ In general, why doesn't the rate increase as the alkyl chain increases in length, based on the reasoning using ring strain in the intermediate? We see that 3-chloropropanol is also another outlier. It seems that the relative solvolysis rates of ω-methoxyalkyl p-bromobenzenesulfonates also follow the same trend, with the rate peaking with the formation of the 5-membered ring. $$\begin{array}{\|c\|c\|c\|c\|} \hline \text{Substrate} & k_\mathrm{rel}{}^\text{[4]} \\ \hline \ce{CH3(CH2)2OSO2Ar^} & 1 \\ \hline \ce{CH3O(CH2)2OSO2Ar} & 0.28 \\ \hline \ce{CH3O(CH2)3OSO2Ar} & 0.63 \\ \hline \ce{CH3O(CH2)4OSO2Ar} & 657 \\ \hline \ce{CH3O(CH2)5OSO2Ar} & 123 \\ \hline \ce{CH3O(CH2)6OSO2Ar} & 1.16 \\ \hline \end{array}$$ The first entry shows the rate of solvolysis without any neighbouring group participation from the methoxy group. References 1. Carey, F. A., & Sundberg, R. J. (2007). Advanced Organic Chemistry Part A. Structure and Mechanisms (5th ed.). Springer. 2. Capon, B. Neighbouring group participation. Q. Rev., Chem. Soc. 1964, 18 (1), 45–111. DOI: 10.1039/QR9641800045. 3. Richardson, W. H.; Golino, C. M.; Wachs, R. H.; Yelvington, M. B. Neighboring oxide ion and fragmentation reactions of 1,3-chlorohydrins. J. Org. Chem. 1971, 36 (7), 943–948. DOI: 10.1021/jo00806a019. 4. Winstein, S.; Allred, E.; Heck, R.; Glick, R. Neighboring methoxyl participation in solvolytic nucleophilic substitution. Tetrahedron 1958, 3 (1), 1–13. DOI: 10.1016/S0040-4020(01)82605-3. • I think for 2-chloroethanol, the rate is high since only a single bond rotation is required for achieving the configuration favourable for NGP while for 4-chlorobutanol the 5mem ring formation increases the rate but when we go to 5-chloropentanol, the rate drops probably due to the low probability of achieving the right configuration required for NGP... however there might be other factors operating here too... – Carrick Dec 24 '18 at 6:51 • Longer the chain the two reacting sites can span over a bigger volume therefore have littler chance to meet and react. In other words is an entropy effect. – Alchimista Dec 24 '18 at 11:58 • This is a standard case of balancing entropy of activation (as Alchimista mentioned) vs enthalpy of activation (as mentioned in your question body) for ring closure reactions. Clayden 2ed pp 805–807 covers it quite well. And for the second table, the authors explain that NGP is not competitive for the 3-membered ring, so the rate is about the same as in the first entry. (I don't immediately see why this is the case, admittedly..) – orthocresol Dec 25 '18 at 4:15 • @orthocresol The gibbs free energy of activation has to do with kinetics. Thus, perhaps, the rate of formation of the 5-membered ring is the greatest. However, if we look at thermodynamic constants, would the equilibrium constant for the formation of the 6-membered ring always dominate? Under the thermodynamic conditions, what would be the major change? – Tan Yong Boon Dec 25 '18 at 13:46 • @TanYongBoon, under thermodynamic control it's difficult to get anything apart from 5- and 6-rings, and all else being equal the 6-membered ring would be preferred, as you said. That said, it will probably also depend on the exact substitution pattern; if you have substituents which can stabilise or destabilise the preferred conformations of the 5- or 6-ring, then things can change. I can't think of a good example – maybe the hemiacetal forms of hexose sugars, where you only really see furanoses (5-ring) and pyranoses (6-ring). – orthocresol Dec 25 '18 at 13:53 Thanks to orthocresol's suggestion to look at Clayden's (2nd ed. p. 805-807), I now have a satisfactory answer which I can now present. We can explain these trends using the Gibbs free energy equation. Except that now, we are now interested in the quantities: Gibbs free energy of activation, enthalpy of activation and the entropy of activation, since we are analysing rate. $$\Delta G^\ddagger = \Delta H^\ddagger - T\Delta S^\ddagger$$ Explaining the decreasing of $$\ce {\Delta H^\ddagger}$$ as the ring size increase $$\Delta H^\ddagger$$ is associated with the ring strain of the resultant ring formed. The larger the ring strain, the larger the value of the enthalpy of activation. Clayden, Greeves, & Warren (2012) explains$$\ce{^1}$$: Firstly, small rings form slowly because forming them introduces ring strain. This ring strain is there even at the transition state, raising its energy and slowing down the reaction. The activation energy for forming a three-membered ring is very high, due to strain, but decreases as the ring gets larger. The data (from pg. 108 of ref. 2) presented here of the strain energy determined for cycloalkanes of varying sizes also supports this trend. $$\begin{array}{\|c\|c\|c\|c\|} \hline \text{Ring size} & \text{Strain energy}^\text{2,}/ \text{kJ/mol} \\ \hline \ce{3} & 115 \\ \hline \ce{4} & 110\\ \hline \ce{5} & 26 \\ \hline \ce{6} & 0 \\ \hline \end{array}$$ Reported to the nearest whole number. Explaining the increasing of $$\Delta S^\ddagger$$ as the ring size increases Think of it this way: a long chain has a lot of disorder, and to get its ends to meet up and react means it has to give up a lot of freedom$$\ce {^1}$$. However, for shorter chains, it is far easier for their ends to meet since these chains have fewer degrees of freedom and thus, the loss of entropy upon cyclisation is less negative. Consolidating the trends Clayden, Greeves, & Warren (2012) reasons that based on the above trends for $$\Delta H^\ddagger$$ and $$\Delta S^\ddagger$$, the activation energy for the formation of the 4-membered ring is the largest. This is because the formation of the 4-membered ring likely has similar $$\Delta H^\ddagger$$ to that for the 3-membered ring while its $$\Delta S^\ddagger$$ is relatively more negative. This seems to agree with the solvolysis rates I have presented: For the ω-chloro alcohols, we see that the relative solvolysis rate is lowest for $$\ce {Cl(CH2)3OH}$$. For the ω-methoxyalkyl p-bromobenzenesulfonates, the formation of the 4-membered ring also has the 2nd lowest rate ($$\ce {k_{rel} = 0.68}$$), with the rate for the 3-membered ring being the lowest ($$\ce {k_{rel} = 0.28}$$). Why does the solvolysis rate not peak at the formation of the 6-membered ring and instead, peak for the formation of the 5-membered ring? This is probably a coincidence. There are 2 opposing trends here so it may be the case that the combined effects of the two trends give different results under different circumstances. ron has provided a graphical representation of the data for strain energy and the entropy of activation here. We do see that in general, there is a peak in the rate of formation of the 5-membered ring. In other words, from the formation of 5-membered ring to formation of 6-membered ring, $$\Delta S^\ddagger$$ becomes significantly more negative. References 1. Clayden, J., Greeves, N., & Warren, S. (2012). Organic Chemistry (2nd ed.). New York : Oxford University Press Inc. 2. Anslyn, Eric V., and Dennis A. Dougherty. (2006). Modern Physical Organic Chemistry. Sausalito, CA: University Science.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 17, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7985868453979492, "perplexity": 1912.034815076928}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-30/segments/1563195525374.43/warc/CC-MAIN-20190717181736-20190717203736-00021.warc.gz"}
http://tex.stackexchange.com/users/1235/hendrik-vogt?tab=activity&sort=revisions	Hendrik Vogt less info reputation 372138 bio website location age member for 4 years, 4 months seen Jan 11 at 7:36 profile views 2,103 Finally I found out what my profile is good for: I can abuse it as a clipboard! @: Welcome to tex.sx! A tip: you can use backticks \ to mark your inline code as I did in my edit. @: Welcome to tex.sx! A tip: If you indent lines by 4 spaces, then they're marked as a code sample. You can also highlight the code and click the "code" button (with "101010" on it). @: Welcome to tex.sx! Note that you don't have to (and shouldn't) sign with your name since it automatically appears in the lower right corner of your post. @: I tidied up your question a bit, hope that's OK.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5071656703948975, "perplexity": 2379.3909062148305}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-06/segments/1422120842874.46/warc/CC-MAIN-20150124173402-00199-ip-10-180-212-252.ec2.internal.warc.gz"}
http://www.physicsforums.com/showthread.php?t=288696	## Adding salt to ice question When salt is added to a ice water solution it makes the ice melt at a colder temperture than zero degrees C. I'm told because it weakens the bonds that hold the ice together. Is the latent heat asorbed by the melting ice at the new lower temperture the same as if the salt was not added and melted at 0 degrees C? Is there the same amount of joules absorbed from the surroundings of the solution to melt the ice if the surroundings are above 0 degrees C? PhysOrg.com chemistry news on PhysOrg.com >> Attacking MRSA with metals from antibacterial clays>> Femtosecond 'snapshots' reveal a dramatic bond tightening in photo-excited gold complexes>> Beautiful 'flowers' self-assemble in a beaker Recognitions: Science Advisor The main effect here is on the entropy of the liquid phase. Most phase transitions are due to what are known as order-disorder transitions. In such cases, there is a competition between the two phases. In the solid phase, the molecules are well ordered such that the interactions between molecules are optimized. This gives the system a low potential energy (enthalpy) at the cost of having low entropy (low disorder). In the liquid phase, the molecules have more disorder (higher entropy) at the cost of losing some of the optimal interactions (higher enthalpy). Remember from thermodynamics that molecular systems would like to minimize their potential energy (like a ball wants to roll down a hill) and increase their entropy (like how it's easy for your room to go from an ordered state to a messy, disordered state but not the other way around). Thus, we have a problem with the solid-liquid transition. Going from solid to liquid raises the entropy (good) but also raises the enthalpy (bad). Conversely, going from liquid to solid lowers the enthalpy (good) at the cost of lowering entropy (bad). So, whether something is solid or liquid depends on whether lowering enthalpy or raising entropy is more important. For reasons that are too complicated to explain succinctly now, temperature determines the relative importance of entropy and enthalpy. At high temperatures, systems would like to raise their entropy more than they would like to lower their enthalpy, and the opposite is true of lower temperatures. So, how does salt play into this? Salt is largely excluded from the crystal lattice of ice so it does not significantly affect the enthalpy or entropy of the ice. However, salt dissolves in water, so it affects both the entropy and enthalpy of the liquid phase. The dominant contribution of the salt is to raise the entropy of the liquid phase. Since the entropy of the liquid phase is larger in the presence of salt, water pays a larger entropic penalty when going from liquid to solid. Therefore at zero degrees Celsius, where the contributions from enthalpy and entropy were previously equal, the balance gets tipped toward the liquid form. This explains why salt can melt ice on roads. To regain the balance between the changes in entropy and enthalpy, one must go to lower temperatures since lower temperatures put less emphasis on the entropic penalty. Recognitions: Gold Member Homework Help ## Adding salt to ice question Quote by philrainey Is the latent heat asorbed by the melting ice at the new lower temperture the same as if the salt was not added and melted at 0 degrees C? Is there the same amount of joules absorbed from the surroundings of the solution to melt the ice if the surroundings are above 0 degrees C? I believe the amount of energy going into the melting ice from the surroundings would be slightly larger due to the addition of salt, as the dissolution of NaCl in water is slightly endothermic. However, this effect isn't connected to the freezing point depression, which occurs as Ygggdrasil described it. Salts that dissolve exothermally also lead to freezing point depression; it's a colligative effect. why I asked this is because I was thinking if one can get the cooling at a lower temperture(-21) from ice frozen at 0 and put in a salt surray, one perhaps could get colder cooling for less energy (refrigeration energy)input as it takes less energy to cool from zero than minus 21. Perhaps adding a contaminate to another fluild (say CO2 ice in a liquid CO2 surray with contaminate). if one trys to separate the water from salt solution by sucking (evapourating off) the water vapour with a compressor does it take more energy to do so than just evapourating pure water? the entropy of the solution is higher than if it were pure water so would there be a lower entropy difference between the salt solution to water vapour than to pure water to water vapour?( I'm thinking the vapour has a higher entropy than a liquid) Would this mean a higher boiling temperture to offset the smaller entropy gain?Or less heat asorbed in the latent heat of the water turning to vapour? Recognitions: Gold Member Homework Help	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8184788823127747, "perplexity": 916.4546289398164}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368698090094/warc/CC-MAIN-20130516095450-00021-ip-10-60-113-184.ec2.internal.warc.gz"}
http://www.randform.org/blog/?p=2167	on amounts The area of the above squares shall visualize a certain amount of money. A little puzzle for randform visitors: The upper outer square visualizes an amount which is … times bigger as the amount of the upper inner square. The lower outer square visualizes an amount which is … times bigger as the amount of the lower inner square. solution: If inkscape doesnt have a bug then the amount which is visualized by the area of the outer square should be in both cases twice as big as the amount visualized by the inner square. I.e. if the inner square visualizes 300 billion $then the outer square visualizes 600 billion$. more precise: the upper inner square has an area of 44 units and thus the upper outer square has an area of 442 units, the lower inner square an area of 11 units. comments in german, french and russian will be translated into english. you can use LaTeX in your math comments, by using the $shortcode: [latex] E = m c^2$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8778160214424133, "perplexity": 1083.1074898437698}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794864624.7/warc/CC-MAIN-20180522034402-20180522054402-00487.warc.gz"}
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Next post: baby g ba 110 manual Previous post: how to do manual accounting	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8772975206375122, "perplexity": 5957.698405921}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780056548.77/warc/CC-MAIN-20210918154248-20210918184248-00419.warc.gz"}
https://asmedigitalcollection.asme.org/MNHT/proceedings-abstract/MNHT2008/42924/453/330608	This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened, horizontal flat surface. Nanofluids are liquids that contain dispersed nanosize particles. Two lubricant based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to a 4% and a 2% volume fraction, respectively. As reported in a previous study for the 4% volume fraction nanolubricant, a 0.5% nanolubricant mass fraction with R134a resulted in a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) of between 50% and 275%. The same study had shown that increasing the mass fraction of the 4% volume fraction nanolubricant resulted in smaller, but significant, boiling heat transfer enhancements. The present study shows that use of a nanolubricant with half the concentration of CuO nanoparticles (2% by volume) resulted in either no improvement or boiling heat transfer degradations with respect to the R134a/polyolester mixtures without nanoparticles. Consequently, significant refrigerant/lubricant boiling heat transfer enhancements are possible with nanoparticles; however, the nanoparticle concentration is an important determining factor. Further research with nanolubricants and refrigerants are required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer. This content is only available via PDF.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8926423788070679, "perplexity": 4004.556219051134}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320300616.11/warc/CC-MAIN-20220117182124-20220117212124-00111.warc.gz"}
https://news.ycombinator.com/item?id=8457345	Curry-Howard, the Ontological Ultimate 75 points by kryptiskt on Oct 15, 2014 \| hide \| past \| web \| favorite \| 80 comments This is very vague about what Curry-Howard means. Curry-Howard means that any type can be interpreted as a theorem in some logical system, and any term can be interpreted as a proof of its type.This does not mean that those theorems have anything to do with your program. Take the following function: swap : forall a,b. (a,b) -> (b,a) swap pair = (snd pair, fst pair) The type here is forall a,b. (a,b) -> (b,a). The logical meaning of this type is (a and b) => (b and a). Note that this is a theorem in logic, not a theorem about your program.This is entirely different than what the types say about your program. Those properties you get from progress/preservation proofs of the type system. Now it is certainly the case that in dependently typed languages you can get the logic from Curry-Howard to express theorems about values in your program. That's the whole point of dependent typing. But it's important to to keep in mind that statements such as this:> Look again at the OCaml Set module example above. You already get a universally-quantified property just from using the type system to guarantee an invariant expressed in an ADT. That’s the import of the Curry-Howard Isomorphism, minus any appeals to more expressively powerful type systems.are nonsense. The fact that the module enforces the property P(n) === S1.mem n (S1.singleton n) = true Q(n) === forall m \in int. m /= n -> S1.mem m (S1.singleton n) = false has nothing to do with Curry-Howard. Which proves Kell's point about the equivocation around type theory. > You express your specification as types (theorems), and your implementation proves those theorems. Then your code is correct by construction. This is a true statement; it isn’t open to debate, not being a matter of opinion.That's technically correct, but a little bit divorced from reality. Let's say I want to write a function that counts the primes below one million. Since that's a function with no arguments that returns a single integer, the corresponding theorem by Curry-Howard is that "at least one integer exists". The function "return 0" is a proof of that theorem. That doesn't seem too useful!You might argue that we should use a richer type system to express the specification. Sure! We just need to express the idea of "primes below one million" in the type system. But that's at least as difficult and bug-prone as writing the program in the first place, so I have a hard time seeing the benefit.Most real world functions are the same way. Say you're programming a game and you need a function to fire the gun. Play the sound, add some screenshake, create a bullet object, etc. Go ahead, express that as a theorem. Don't forget to come back and tell us what you gained by doing that. >You might argue that we should use a richer type system to express the specification. Sure! We just need to express the idea of "primes below one million" in the type system. But that's at least as difficult and bug-prone as writing the program in the first place, so I have a hard time seeing the benefit. Theorem primes_below_million_spec: forall l m, (forall p, In p l -> p < 1000000 /\ ~exists n, n <> p /\ n <> 1 /\ Divisible p n) -> length l = m -> primes_below_million = m. Done. I think that's missing an implementation of the function that matches the type. Is that also easy? That's not so easy. That's the point, right? It's easier to write a specification than an implementation, so it's valuable to check that the implementation satisfies the spec. Well if I wasn't so lazy, it would be easy to implement a Sieve of Eratosthenes algorithm yielding a list of primes up to some number, and then another function feeding 1000000 to that function and returning the length of the resulting list. The hard part would be actually proving the theorem I stated in terms of those two functions. Let's go further. If I'm writing, say, numerical calculations, types can save me from getting kilometers when I expect miles (or, worse, kilograms). What it can't do is save me from numerical instability, round off errors, and a whole host of other problems known to the field of numerical analysis.If my code is calculating the angle of a control surface on a plane, the type system is not going to say anything about whether I get 40 results every second. Without those constant, timely updates, the plane is going to crash.A robust type system means that "your code is correct by construction"? That seems incredibly naive. There's more ways for programs to be wrong than are provable via a type system. Concerning 'numerical instability': with a sufficiently advanced type system you should be able to save yourself from something like numerical instability. You could e.g. ensure all numbers have an 'order of magnitude type' and define operations between 'order of magnitude' types to raise errors for certain (ranges of) combinations. However, there is (AFAIK) no convenient way to express this in any language, let alone without performance suffering greatly. Um, maybe you missed the point about dependent types? You can express a function, that takes no arguments, that returns primes below 1,000,000 as it's type! That's kind of the point of the talk, and is supposed to be possible in languages like Agda and Idris (I don't know enough about them to give any syntax here). See jules' comment below about how curry-howard does not mean your implementation is a full proof as well.Considering code that flies planes and shoots guns generally is written using proofs on control systems (if not required by law), your examples are a bit weak. The constructive nature of Idris makes it hard (at least for me) to express a prime under 1,000,000 as a type. For example, it's trivial to express a composite as a GADT: data Composite : Nat -> Type where factors : (x : Nat) -> (y : Nat) -> Composite ((S (S x)) * (S (S y))) but there is no analogous construction of a prime type. Luckily most day to day programming looks more like the composite case than the prime case. As an example, here's how primality is defined in the Agda standard library. It is simply the negation of the property 'has a divisor and is greater than 2'. It seems to me that using dependent types to express the type "the number of primes below one million" would take at least as much code, and be at least as error-prone, as writing that function in a dynamically typed language directly. In fact I'd be surprised if the dependently typed version were less than 2x the size of the direct version. This is why they brought up the language that uses the same syntax for types as it does for your function definition.It really sounds like you haven't played with Coq or Agda.. because expressing these things are not that much code at all. Also the presentation literally covers that complaint, and how they think more programming languages are needed. But the "proofs" of those control systems isn't anything that looks like a type system, is it? (An argument of the form "due to Curry-Howard, all proofs are type systems" will be regarded as uninteresting at best.) Absolutely not, at least not to me. I'm not a huge type theory guy or anything.But saying that "proofs are a burden especially for things with side effects like shooting a gun" when systems that shoot guns specifically do have proofs in spite of their type systems invalidates the example, if not the argument.The presenters certainly think these languages will help construct those proofs.. that I'm less certain of. Again, how he gets this from Amanda’s and my presentation is beyond me Yes, I don't doubt it is beyond him. Yet he is one of only two very smart people with very interesting things to say that managed to get themselves removed from my various feeds, because I just couldn't stand their idolatry of static-typing and never ending condescension of anything remotely critical of it anymore.I haven't seen the presentation, but I don't for a second doubt they implied that: If somebody stays away from typed languages, it [means] they’re stupid, or lack education, or are afraid of maths. There are [no] valid practical reasons for staying away [from type languages]. He believes they were being very constructive, showing an understanding for other opinions and taking a nuanced view of static typing, with an eye for valid criticisms. I know, from the online reviews, many did not experience the talk that way. Reading this debate has been an exercise in sifting valuable commentary from a bunch of opinionated drivel, on both sides. In particular, the current article suffers from the author assuming that every single comment is addressed to his presentation, despite it getting a very brief mention near the beginning. The 'seven deadly sins' article had a better tone, but still spent most of its time on non sequiturs and anti-intellectual cheap shots.I'm quite interested in type systems (and the lack thereof) but the level of debate around them is astonishingly poor. It's also odd because Kell only specifically accuses the Snively/Laucher talk of committing two of the "seven deadly sins", and that isn't one of the two. I think he took Stephen Kell's post as a direct response to their talk when in fact Stephen Kell's post was about the entire culture around static typing and their talk is only one small piece of it. Yes, and the interesting thing is to me this exactly demonstrates the problem that is being pointed out by Kell (for the community in general) and by me (for Snively in particular).What I feel this blog post demonstrates is that if you are somewhat critical of something Snively says, you are met with a barrage of arguments that counters everything you said in all the ways he could possibly find to disagree with them. That motivation will always lead to some ridiculous and only remotely relevant disagreements, which are now being pointed out here and over on Reddit.This blog post feels like it was written in anger: the enemy must not just be refuted on some points: he must be destroyed. His credibility must be tarnished by showing he didn't get anything right.I think I understand this, because I used to do this. I stopped because I wondered why I was so often getting into ridiculous, irrelevant, arguments about things that I didn't even care about but that just came up in a discussion. Proving the other wrong in any way became more important than finding an answer to the question before us. I've been guilty of this too. The funny thing is, if you actually want to win an argument that's exactly what you shouldn't do. If you respond to everything the other person said, and refute each of this points, then inevitably somebody will come along and take one of your refutations of an unimportant issue and point out a factual error in your refutation. Even if you are 100% correct, somebody will come along and misinterpret one of your sentences. At this point you've lost the debate, because now the entire debate is focused on that small point that you got wrong, and it can be difficult to steer it away from that onto the more important issues.No, if you want to win an argument you should do exactly the opposite. You should find one weakness in your opponent's argument, and then make a bulletproof refutation of that. You may think that because he made other points that are wrong it's better to point out all the ways in which he is wrong, but that's a bad strategy. Inevitably you will be wrong or misinterpretable in one of your many refutations and then you've lost.Both of these strategies are of course detrimental to having a productive debate ;-) Can you recommend some even-handed reading on the opposing views here? This comment by Matthias Felleisen's is a very polite and well-considered position from an academic on the dynamically-typed side of the spectrum: http://existentialtype.wordpress.com/2014/04/21/bellman-conf...Harper himself can't be relied on to be so cordial, unfortunately. Speaking of the culture around static typing: Bob Harper's blog, where Matthias Felleisen gets 15 downvotes per courteous, thoughtful response... Seems like voting has now been turned off, or at least I don't see any votes any more. I'm not sure that there are any opposing views here. I think that once you filter out the actual arguments, they are mostly independent of each other. Which opposing views did you take away from these two blog posts? Curry-Howard is central to how you think about programming vs. Curry-Howard is almost completely irrelevant to how you program?But maybe that disagreement goes away if I restate it slightly: Curry-Howard is central to how you think about programming vs. Curry-Howard is almost completely irrelevant to how you actually write programs. That is, if I am actually in the process of writing a program, I don't think about Curry-Howard very much, even if I'm working with the type system in Haskell. If I think about programming at a highly abstract level, then, OK, Curry-Howard might be considered a central insight. The talk he's defending was tiresome and dripping with condescension (I agree with Stephen Diehl: https://twitter.com/smdiehl/status/519160854517149696). Typed-language folks don't need advocates who waste breath talking about "incompetent Ruby developers moving to Clojure" and whatnot. There's enough positive stuff to talk about! I think the folks who gave that talk need to read Gershom Bazerman's (a person who has no trouble giving talks filled with excitement about type- and category-theoretic concepts with no condescension) excellent post here: http://comonad.com/reader/2014/letter-to-a-young-haskell-ent... It seems oddly defensive for Paul Snively to interpret Stephen Kell's "Seven Sins" essay as being mostly about his (and Amanda Laucher's) Strange Loop talk – sure, their talk was mentioned as an example in passing (along with another talk about Rust), but in no way is the essay specifically about their talk. The seven sins essay addresses the entire discourse about static and dynamic typing; whether one particular talk exhibits a particular "sin" or not doesn't mean there's not a real problem. >>In a typed language, only polymorphism which can be proved correct is admissible. In an untyped language, arbitrarily complex polymorphism is expressible.>This misses the point, which is that “arbitrary” has proven to be unlikely to be correct. Ultimately, this argument comes down to “you should trust human programmer intuition,” which I gladly admit to being an assumption I’m unwilling to make.It's true that “arbitrary” has proven to be unlikely to be correct in the general case.However, allowing untyped types(?) has also proven to be useful. I think this is because there is yet to be a language that makes expressing complex types easy.We work in an environment where FizzBuzz is considered a good way of filtering people who can program.I'm generally a proponent of "strongly typed" languages. But I do worry about the cognition overhead the syntax causes, and I do wonder if there is a "better way". > I'm generally a proponent of "strongly typed" languages. But I do worry about the cognition overhead the syntax causes, and I do wonder if there is a "better way".What about dynamic language + runtime type checking + (nearly) 100% test coverage? You get the flexibility of a dynamic language and the safety of a static type language (in fact you get more, since runtime type checking is more powerful). 100% Test Coverage means that every code path is executed by the test suite. This is probably a good thing.Yet it does not mean that the code is correct for any definition of "correct" other than "passes the associated test suite." One unit test makes a line of code covered. It does not make the domain of inputs covered - 100% coverage does not mean that corner cases have been handled correctly - or that they have been considered at all. Again, all it means is that every line of code was executed at least once.There are useless tests: def test167 [ if [ val == foo(8); return true] then return passed else return failed endif ] enddef This of course is true. But some test coverage tools with give you path coverage which helps with that.Of course, this doesn't really substitute for a type system either. It can be very costly to achieve 100% test coverage and static verification can reduce this cost by giving you some tests "for free". For example, you never need to write a test to check for null-pointer-exceptions if you code in Haskell.Static types also help in situations other than testing. For example, you can use "guardrail programming" to be much more liberal when refactoring things: want to change a function signature? Just change it and the compiler will point out what other parts of the code need to be updated. This is even if you haven't written a test suite yet or are doing big changes that invalidate the old test suite.That said, I think the perfect world would be one that lets you mix dynamic and static typing in a single program (some things are hard to verify statically, but would be nice if we could at least express them as types) but I think we are still a way off that being a practical alternative. I know in C# they have the dynamic keyword which allows for dynamic typing when you need it, but lets you use static typing when you don't. Yes, C# and lots of other language have that feature. Where it gets really tricky is if you want to dynamically check the type of functions or objects, since you need to run the assertions when the function/method gets called rather than when the function/method gets assigned to some reference. Its also tricky to give a parametric type to code that is implemented with dynamic types. I'm not convinced that requiring test coverage is a good trade off.Don't misunderstand me: tests are good. But language syntax that makes some bugs impossible is also good. The cognition overhead of 100% test coverage is probably absurd, as well. Probably you are right, but for a library I think it should be an obligation to provide 100% coverage. For a generic program, maybe I sould provide 100% coverage at least of the "critical paths". Might also be worth it to emphasize the "intended paths."Of course, that is probably just saying that there should be documentation. Especially given that you can't reasonably enforce the rigor of your test suite by way of your language. Oddly, you could, in a way. Just treat your language and compiler as a tool in the toolchain. Add in a testing segment and you can set rules on it. I still don't understand the notion that dynamic types gives you anything more than static types. Are there really usefull programs that can't be written in, say, Haskell? IMO, its not just about what useful programs you can write. Its also about how much of the type system you need to learn to get the program to compile. For example: function foo(f){ return [f(["1", "2", "3"]), f([1,2,3])]; } function length(xs){ return xs.length; } foo(length); Anyone can see what this Javascript program doing but to write the Haskell equivalent you would need to understand higher-rank-types and enable the corresponding language extension, which gets in the way of beginners. Unfortunately I do not know so well Haskell to give you an answer. I was referring to this:> I think this is because there is yet to be a language that makes expressing complex types easy.Since I'm obliged to use a dynamic language (JavaScript) I'm looking for a solution in it. And in JavaScript is really easy to express a complex type, say "the set of all the even integers between 2 and 14 but 10", using runtime checking to enforce the constraints. Is it simple in Haskell to define such a set in its type system? Simple? Yes. Pleasant? Not really. I'm not a Haskell expert but I can write that type in Scala (the Haskell version probably has less boilerplate, but still some): sealed trait Even[N <: Nat] object Even { implicit object zero extends Even[_0] implicit def evenSS[N <: Nat](implicit e: Even[N]) = new Even[S[S[N]]]{} } sealed trait EvenAndBetweenTwoAndFourteenAndNotTen object EvenAndBetweenTwoAndFourteenAndNotTen { implicit def forN[N <: Nat](implicit e: Even[N], le2: Le[_2, N], le14: Le[N, _14]) = new EvenAndBetweenTwoAndFourteenAndNotTen[N]{} implicit object interfere10 extends EvenAndBetweenTwoAndFourteenAndTen[_10] } Like I said, it's cumbersome, but there's nothing actually complicated about writing this, it's just boilerplate to represent it in the type system.On the other hand, in Idris or the other languages mentioned in the article, you should be able to write that kind of constraint at the type level just as easily as you can at the value level. That's where it gets really exciting. In javascript, any method that relies on receiving a value of "the set of all the even integers between 2 and 14 but 10" should probably check that it did in fact receive such a thing or it might be buggy. In a statically typed language, that check can easily be centralized to wherever an EvensFrom2To14Without10 value is constructed.Here's an example in rust[0]. If the print_bare method relies on only receiving even numbers between 2 and 14 excluding 10, then it is buggy, because it isn't checking its input, but the print_tagged method is correct without needing to check! That's not really expressing a complex type in JavaScript, its expressing a complex (such as it is) runtime constraint -- which you can do easily in Haskell as well. JS doesn't give you anything Haskell doesn't there.Its true that to make that a proper, statically-enforced type in Haskell takes some complexity, but if you aren't willing to do that, you could make it a runtime-enforced constraint on a statically-enforced type of integers as easily in Haskell as, in JavaScript, you could make it a runtime-enforced constraint on a value that is not statically enforced to be anything more specifically than a valid JS value. I do not know Haskell enough either. But I didn't really mean 'using type system everywhere'. About your question, from what I've seen you can always go symbolic : define an abstract thing as twofourteenexceptten that represent that idea and use it. Or just use a filter everywhere to ensure that function requiring a 2and14but10 won't be called on something with other numbers. In that case you're not losing anything you'd do with a dynamic language. Even Haskell has some kind of dynamic types. Well, does it fucking not have dynamic types? Make an argument instead of just downvoting. The nice thing about dynamic types is that they give you the expressive power to code things that would not be allowed (or at least not encouraged) in your type system, even though they might be allowed in a different type system. Back in the day, one notable example of this was parametric polymorphism: it comes "for free" in even the simplest dynamic language but took a while to become mainstream in static languages.IMO, in an ideal world you would able to choose between dynamic and static verification of types depending on what your program is doing. This might even let us work with richer types than we do now! For example, most typed languages still do dynamic tests for array indexes because doing those statically requires dependent types (which are hard to use and not always worth the trouble). But if we had a language that lets us talk about the array lengths in the type system we would at least be able to give better error messages if something goes wrong, even if we only find out about it at runtime. > This stuff often ends up explained in very academic language,What, that software should be correct according to the specification (either a formal one or an informal and implicit one)? Because that's the academic motivation I've found for things like type systems and program specification. I mean like "Curry-Howard isomorphism" and "state space" and "monad" and such. It makes it very easy to dismiss as academic wankery, which is helped by the fact that, well, yeah, some of it is, honestly. But under that academic wankery is some brilliantly practical stuff that is hard to learn from the communities that are over-focused on "practicality". > I mean like "Curry-Howard isomorphism" and "state space" and "monad" and such.What's the problem with those? Regarding the referenced talk at Strange Loop, I have noticed that I have yet to see a good talk ever done in that style where dual-presenters oscillate back & forth. Especially when they're trying to elicit laughter. I did manage to enjoy the talk between cringeworthy moments, at least.There is an interesting slide at around 21:00 where they show four quadrants that represent:What do you get when you pass a Term to a Term? (a function)What do you get when you pass a Type to a Type? (templates, generics, type variables)What do you get when you pass a Term to a Type? (dependent types)What do you get when you pass a Type to a Term? (inheritance, overloading)It was an interesting slide. It manages to make dependent types seem like an essential missing piece for the sake of symmetry. I'm not sure I understand the last one, though: how is inheritance and/or overloading the act of passing a type to a term?Does anybody know if this idea is explained better elsewhere? That slide was a simplification of the Lambda Cube that they showed right at the end. That's probably a good starting point for better references: http://en.wikipedia.org/wiki/Lambda_cube ... the wiki page isn't particularly approachable, but there's more detail if you follow the links. Just took a quick look at paper #2, which is quite fascinating -- to try and isolate the effects of static / dynamic typing, they developed two slightly different programming languages which varied along only this axis.I have some sympathy with this approach, but I'm not convinced you can actually separate things in this way. The type systems I actually find useful are not just a static analysis layer, but have significant impacts on the semantics of the language and the way libraries are designed. I'm not sure you could just 'turn off' the type system in Haskell and have anything even remotely sensible, for example.I sometimes wonder if there's enough mature open-source projects in the wild now to be able to draw some statistical conclusions about the long-term effects of language choice, but that would be quite a project... > I'm not sure you could just 'turn off' the type system in Haskell and have anything even remotely sensible, for example.You can actually do exactly this:https://ghc.haskell.org/trac/ghc/wiki/DeferErrorsToRuntimeOf course, the type system doesn't vanish but checking types is deferred until runtime, turing Haskell into a dynamic language with an unusually elaborate tag system. It's still not comparable to a dynamic language however. Simply constructing a list [1, "Hello"] will already produce an error. Dynamic languages usually allow this, and only signal errors when the values are used in an erroneous manner, like 1 + "Hello". It does exactly what it says on the tin: it displays type errors that were found at compile time with the same type system that regular Haskell uses, but the actual displaying is deferred until run time. There is no actual tag checking going on at run-time. It does make Haskell a dynamic language, but also isn't really what's meant. Generally when people compare statically typed languages and dynamically typed languages, what they are doing is comparing the various ways in which the type system imposes restrictions.The way in which Haskell differs most strongly and obviously from Ruby is not that it catches the type errors at compile time - but that the type errors can be caught at compile time. This in general allows smarter tools - compare Eclipse for Java and the 'type hierarchy', 'find method calls', many refactoring calls and the far less rich tools available for Python. Thanks so much for this point. I think the key here is conclusion (3) about semantic errors.I remember endless discussions about the Liskov Substitution Principle and how it relates to subtyping/subclassing. I think what people easily forget that static types do almost nothing for semantics and the notion of "behavioral subtyping" is a lot more interesting but also a lot more elusive.And I say all this as a lifelong static typer, by the way, and not even of the fancy Haskell variety. I know what not to expect from static type checking so I'm a lot happier with what it does provide me. Before even loading up the papers I knew they'd be using some horseshit type system like Java's. The programming tasks did not require complex data structures (such as a scanner and parser), so one would not expect Java's type system to be a limiting factor. This comment alone is enough to make Haskellers (or other proponents of good type systems) not take this seriously.Anything trying to cast broad strokes about the usefulness and effectiveness of type systems can't use a language with a type system like Java's. And your comment is enough to make people not take you seriously. You sound like a stuck-up jerk rather than a thoughtful person.Perhaps you could explain exactly what it is about Java's type system that makes it not worth even discussing. That would be a comment that was actually useful. (And don't say something like "because Java doesn't have higher-kinded types". We know that it doesn't. What about that lack makes it not even worth discussing?) I stated the problem with citing that research when trying to appeal to people familiar with Haskell-like type systems (as in the linked blog post).My real point is that you can't really draw strong conclusions from this research when talking about type systems in general. If you wanted to say "It doesn't seem like type systems like Java's improve productivity" then I wouldn't have any issues, and would probably even agree.> You sound like a stuck-up jerk rather than a thoughtful person.I will agree that I phrased what I said a little harshly, but damn. OK, now you sound like a thoughtful person that I can actually have a conversation with. And I probably responded a bit overly harshly, too.But I keep seeing this "Java's type system is essentially worthless" idea, tossed off glibly as if it was God's own truth, and I've never seen a justification for it. I get that it's not Hinley-Milner. I get that it doesn't have higher-kinded types. Why does that make Java's type system worthless? As a type system, purely formally speaking, Java is... well, it's just kind of OK.It has parametric polymorphism. It gets subtyping & co-/contra-variance right -- for generic types only, not arrays, and requires explicit annotations ("extends", "super"). It can express higher-order functions. Its primary formal weakness compared with, say, Haskell98 or SML, is the lack of higher-kinded types (ignoring for the moment the issue of Haskell-style typeclasses or ML-style modules & functors), which is a pretty big weakness but not a game-killer (see: Rust, Elm).But pragmatically, it's a pain in the ass to work with. (Possibly this has improved since I worked with it. I hope it has!) It has a weird "everything must be an object" view of the world; it requires a file for every type I wish to define (barring nested classes, and anonymous classes - the latter of which is a notable but late improvement). Expressing HOFs is possible, but very unpleasant (AIUI it's gotten better lately). And just to top it all off, it doesn't have type inference, which just makes everything a chore.The way I see it, Java is playing catch-up with the innovations introduced by more forward-thinking languages. It seems doomed to being forever a middle-of-the-road language. Which is... well, it's just kind of OK.But it's not gonna inspire devotion, and people who worked with it when it really did suck (perhaps it still does, I dunno) are gonna remember that and hate it. Thanks for the answer. But could you clarify something for me? What's the difference between higher-order functions and higher-kinded types?And, yeah, Java's type system... I'm not going to claim enthusiasm, merely that it seemed adequate for what I wanted it to do. > But could you clarify something for me? What's the difference between higher-order functions and higher-kinded types?roughly, the relation is:(type constructor):(simple function)::(higher-kinded type):(higher-order function)That is, a higher-kinded type is a type which takes a type constructor as one of its parameters, in the same way that a higher-order function is a function that takes a function as one of its parameters. Obviously, it's not worthless, that's just hyperbole, but it's sad to see people who would probably be the first to say that they are reasonable, evidence-based, pragmatic computer engineers fall into the manichaean trap that is extremism: either something sucks (Java) or it's awesome (Haskell).The truth is that Java's type system is a bit in-between. It's a reasonable type system that's tractable for a huge portion of the developer community (hence its success) but which falls short of some required qualities to be able to show proofs by applying the Curry-Howard isomorphism. Parsing, at least, absolutely can benefit from a powerful type system: consider Haskell's Parsec library, which uses monads & monad transformers to express a powerful parser combinator system. Writing a parser combinator library does not require a powerful type system, especially not a custom one for a specific task (the students who were doing the scanner/parser task were limited to an environment where they had no access to third-party libraries, not that any existed for the language they were given). For a simple parser combinator implementation from scratch you require nothing more than basic types and the type of whatever AST you're generating. Parametric polymorphism is useful when you want to write a reusable parser combinator library, something that wasn't necessary, but even then you don't really need more than that (see other existing parser combinator libraries).Higher order functions can make your life easier, but note that the students had access to a Java-like language (of which there was both a statically and a dynamically typed version) with Ruby-style closures, so that wasn't an obstacle. Fair point.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4271846115589142, "perplexity": 1089.9791474685014}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039742338.13/warc/CC-MAIN-20181115013218-20181115035218-00398.warc.gz"}
http://gmatclub.com/forum/so-you-hate-your-kaplan-instructor-52819.html?sort_by_oldest=true	Find all School-related info fast with the new School-Specific MBA Forum It is currently 23 May 2015, 05:45 ### GMAT Club Daily Prep #### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email. Customized for You we will pick new questions that match your level based on your Timer History Track every week, we’ll send you an estimated GMAT score based on your performance Practice Pays we will pick new questions that match your level based on your Timer History # Events & Promotions ###### Events & Promotions in June Open Detailed Calendar # so you hate your kaplan instructor... Author Message Senior Manager Joined: 14 Jun 2007 Posts: 399 Followers: 1 Kudos [?]: 10 [1] , given: 0 1 KUDOS well DONT. It probably isn't their fault. Let me explain. I took a job with Kaplan teaching GMAT at night. I figured I could save some extra money because I am quitting my job once I start grad school, and what kind of part time job is going to pay you $20 an hour? I've given lectures to college students on various topics. I've tutored folks in calculus. I have even tutored someone privately on the GMAT. Everyone has always been happy with their experience with me. My performance reviews from the Kaplan folks who sit in on your first classes have been really low. They grade me on the biggest bullshit - I have to say: "Kaplan" "GMAT" "Test Day" "Higher Scores" "Online Resources" "Homework" at least once every third of a page. I wish I was kidding. What the ** is that? Who the hell can teach material when you are worried about such inane bullshit? Many times I've only got 3 minutes to cover a topic, but a full third of that is taken up with these meaningless crap. Oh and that brings me to their "materials". Well, THEY SUCK. My teaching really suffers because I have no faith in what I am doing. It is hard to be excited in class when you feel bad that, deep down, you know what you are teaching is either wrong, or some bullshit strategy that takes longer to use on test day than learning how to do it the "textbook way" and calculating something proper. the way I have demonize the "textbook way" in class is also apalling to me. the "textbook way" a.k.a. using actual mathematics is essential for a high GMAT score and success in B-School. Granted, "strategies" like backsolving and picking numbers have their place and come in handy - they should not be the focus of anyone's test prep plan. BTW - Kaplan acts like they ** invented picking numbers and backsolving. give me a break. I never even touched a kaplan book when I prepped for my GMAT, and I backsolved a mixture problem on test day. It's freaking common sense people!!! The classes are so short, and crammed with so much retardation, that students don't have much time to ask questions or have discussion if needed... which thankfully they don't. BTW, THERE IS HARDLY ANY TIME DEVOTED TO MATH IN CLASS. I feel that this is a huge rip off, because many students are not made aware of this. If you are reading this thinking to yourself, "hey I need to brush up on math, let me take Kaplan GMAT class" WELL DONT! /rant over Last edited by anonymousegmat on 26 Sep 2007, 09:15, edited 1 time in total. Kaplan GMAT Prep Discount Codes Knewton GMAT Discount Codes GMAT Pill GMAT Discount Codes Manager Joined: 25 Jul 2007 Posts: 88 Followers: 1 Kudos [?]: 5 [0], given: 0 [#permalink] 25 Sep 2007, 08:08 I think Kaplan tries too hard to be all things to all people, and maybe that's affecting their ability to retain quality instructors and produce quality material. And these so-called "strategies" are hallmarks of Kap & PR - useful for saving time, counterproductive if you don't have the fundamentals down (leads to more confusion). SVP Joined: 24 Aug 2006 Posts: 2134 Followers: 3 Kudos [?]: 98 [0], given: 0 [#permalink] 25 Sep 2007, 08:30 Taught SAT at Kaplan and that experience sounds about right. "Test Day" "Higher Score" hahahaha I remember all too well. What I did was cover the Kaplan material very quickly then gave some of my own examples that made the students understand better. There's barely any time to finish the entire lesson. But it was overall a somewhat frustrating experience. Manager Joined: 29 Aug 2007 Posts: 80 Followers: 1 Kudos [?]: 1 [0], given: 0 [#permalink] 25 Sep 2007, 12:40 WOW. I have never heard this before either, and I did a lot of research before I started prepping. Makes me glad I'm taking an online course, although mine is with Princeton Review. I am getting plenty of practice on the fundamentals (math is my weak area) and am definitely able to maximize my time rather than listening to marketing drivel. I don't know if PR instructors do that in class, but so far, not through the online chat. I was initially lamenting not being able to do a classroom course, but now I am feeling pretty good about that!!! CEO Joined: 29 Mar 2007 Posts: 2589 Followers: 16 Kudos [?]: 238 [0], given: 0 [#permalink] 25 Sep 2007, 23:03 Im so glad I cancelled my class w/ Kaplan. Saved 1200$ and spent only 840\$ on MGMAT online course. MGMAT has been AWSOME. Use OG, books that actually teach you the concepts. I bought the Kaplan book and used it until I found MGMAT. Since then, i never bothered to open the book again. I wanted to sell it, but who wants that crappy book ;P. (anyone need a paper weight? Burning material?) Senior Manager Joined: 14 Jun 2007 Posts: 399 Followers: 1 Kudos [?]: 10 [0], given: 0 OMG, I can't believe this is a sticky! I feel honored! Senior Manager Joined: 14 Jun 2007 Posts: 399 Followers: 1 Kudos [?]: 10 [0], given: 0 Calamity Jane wrote: WOW. I have never heard this before either, and I did a lot of research before I started prepping. Makes me glad I'm taking an online course, although mine is with Princeton Review. I am getting plenty of practice on the fundamentals (math is my weak area) and am definitely able to maximize my time rather than listening to marketing drivel. I don't know if PR instructors do that in class, but so far, not through the online chat. I was initially lamenting not being able to do a classroom course, but now I am feeling pretty good about that!!! Calamity, Kraplan does give students plenty of 'online resources' so they may 'score higher' when they take the 'gmat' on 'test day' and they do have math review modules online that students can do for 'homework'. however, we are told right off the bat in our first quant training video that "kaplan doesn't offer math classes, or even a math review" and i don't think customers buying into a kaplan class know that... what the hell is the first thing you think of when you sign up for a GMAT class???? MATH REVIEW!!!! Here is an example of what I mean: The whopping 10 minutes I get to explain combinatorics and permutations to the class is fantastic. Considering a whole chapter of my PreCalc textbook was devoted to these two topics, I am really scared when I have to teach this lesson... who is going to be able to understand such things in 10 minutes? Especially since 25% of my time I am just spouting catchphrases and marketing nonsense Manager Joined: 29 Aug 2007 Posts: 80 Followers: 1 Kudos [?]: 1 [0], given: 0 Yeah, that's pretty much why I wanted to take a course, for the math review. I've been out of school for a while, so that's key. GMAT Instructor Joined: 04 Jul 2006 Posts: 1269 Followers: 23 Kudos [?]: 161 [0], given: 0 As a former Kaplan instructor, I can say that you have a lot of leeway in terms of what you teach and how you teach. Get students to do session 2 on their own at the end of the course, and you will have more time for more work on topics that students find difficult. Intern Joined: 21 Jun 2007 Posts: 11 Followers: 0 Kudos [?]: 0 [0], given: 0 So, I teach for Kaplan and my students love me and do really well on the test. Honestly, teaching is fairly idiosyncratic. Sure there is a basic curriculum to teach, but every teacher at my center has lots of leeway to amend and add onto the course. Also, Kaplan students can move around to different classes as they please. So if you don't click with your initial teacher, then you can jump into a different class no charge. I don't think other test prep companies allow that, but I could be wrong. Manager Joined: 12 Dec 2012 Posts: 230 GMAT 1: 540 Q36 V28 GMAT 2: 550 Q39 V27 GMAT 3: 620 Q42 V33 GPA: 2.82 WE: Human Resources (Health Care) Followers: 2 Kudos [?]: 51 [0], given: 181 Re: so you hate your kaplan instructor... [#permalink] 14 Mar 2013, 06:10 Any more recent experiences ? _________________ My RC Recipe http://gmatclub.com/forum/the-rc-recipe-149577.html My Problem Takeaway Template http://gmatclub.com/forum/the-simplest-problem-takeaway-template-150646.html Re: so you hate your kaplan instructor... [#permalink] 14 Mar 2013, 06:10 Similar topics Replies Last post Similar Topics: GMAT Instructor at PR or Kaplan 0 08 Mar 2015, 17:44 1 Kaplan Instructor: A question of your CAT 5 15 Dec 2014, 15:23 1 I hate you gmat 4 24 Aug 2014, 01:29 11 Why do YOU hate the Gmat? 24 13 Aug 2011, 16:55 1 Sell my soul and be a PR/Kaplan Instructor? 15 12 May 2008, 21:11 Display posts from previous: Sort by # so you hate your kaplan instructor... 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http://clay6.com/qa/553/choose-the-correct-answer-the-probability-of-obtaining-an-even-prime-number	Browse Questions # Choose the correct answer: The probability of obtaining an even prime number on each die, when a pair of dice is rolled is $\begin{array} ((A) 0 \quad & (B) \frac{1}{3} \quad & (C) \frac{1}{12} \quad & (D) \frac{1}{36} \end{array}$ Can you answer this question? When a pair of die is rolled once, the sample space consists of 6 $\times$ 6 = 36 elements. Of the possible outcomes, the only even prime number is 2, and getting a 2 on each die can occur only once. Therefore the P (obtaining an even prime number on each die, when a pair of dice is rolled ) = $\large\frac{1}{36}$ answered Jun 19, 2013	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.84903883934021, "perplexity": 308.858583794472}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-04/segments/1484560279915.8/warc/CC-MAIN-20170116095119-00275-ip-10-171-10-70.ec2.internal.warc.gz"}
http://mathhelpforum.com/advanced-statistics/85607-advanced-statistics-questions.html	# Math Help - Advanced Statistics Questions I have two questions: 1) Let X_1, X_2, ..., X_n be i.i.d. from a distribution with pdf: I am supposed to find the MLE (maxmium likelihood estimator) for theda. However, if I take the derivative of the likelihood function (Likelihood function given below) and set it equal to zero, it doesn't work. I must maximize the likelihood function a different way then. I argue that in order for the likelihood function to be maximized, (which is the first order statistic; thus "theda hat" equals the minimum). Is my logic correct? 2) Let X_1, X_2, ..., X_n be i.i.d. with distribution Laplace(u,1). Find the Fisher information for u. Here's the pdf: When I solve the Fisher information, I_n (u), I get zero... is this right? If not, what is another way to solve it? Thanks for the help! 2. nope, the largest the joint density can be is when theta is as small as possible. You have $I(0\le X_{(n)}\le \theta)$. Hence the LARGEST order stat not the smallest is the MLE. It's sufficient too. 3. Thanks, matheagle! Considering I did that one wrong, check my work on the following (which I thought I did correctly): Let X_1, X_2, ... , X_n be i.i.d. from a distribution with a pdf: FYI: I noticed that this a: . Find the MLE for sigma. Again, like the previous problem, the derivative of the likelihood function won't help me, so I look the at likelihood function: I argue that the likelihood function is maximized when sigma is minimized. However, sigma can only be as small as the largest order statistic because of the bounds of X. So, Am I right? I am a little hesitant of my answer because mu is also in the bounds of X, so I don't know if I have to include mu somehow in there as well. Thanks again! 4. Sorry. I'm no longer answering questions here.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 1, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9825426340103149, "perplexity": 623.8486792375822}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-10/segments/1394678697363/warc/CC-MAIN-20140313024457-00082-ip-10-183-142-35.ec2.internal.warc.gz"}
https://tracker.moodle.org/browse/MDL-26511	# Adding images in Cloze vertical and horizontal display multiplechoices subquestions ## Details • Type: Improvement • Status: Reopened • Priority: Major • Resolution: Unresolved • Affects Version/s: 2.0.3 • Fix Version/s: None • Component/s: • Labels: • Testing Instructions: Hide Mainly import the some questions from https://tracker.moodle.org/secure/attachment/32973/questions-T-26511_with_or_no_images-20130604-2349.xml which put specific images in the question text, answers for multi and feedback for all question types and the same questions without images. Check the behaviour of set_subquestions_elements_itemid($question, '@@PLUGINFILE@@'); and looking at the file table records that the setting of image links are only created if there is an image in the given element. This also verify that the import is OK. Then edit copy the questions. test the decode verify display, save the question. This will test the filtering process set_subquestions_elements_itemid($question, 'draftfile.php'); Create a copy of the question to another category. Move the questions to another category and context. Create a quiz, test OK. Show Mainly import the some questions from https://tracker.moodle.org/secure/attachment/32973/questions-T-26511_with_or_no_images-20130604-2349.xml which put specific images in the question text, answers for multi and feedback for all question types and the same questions without images. Check the behaviour of set_subquestions_elements_itemid($question, '@@PLUGINFILE@@'); and looking at the file table records that the setting of image links are only created if there is an image in the given element. This also verify that the import is OK. Then edit copy the questions. test the decode verify display, save the question. This will test the filtering process set_subquestions_elements_itemid($question, 'draftfile.php'); Create a copy of the question to another category. Move the questions to another category and context. Create a quiz, test OK. • Affected Branches: MOODLE_20_STABLE • Pull from Repository: • Pull Master Branch: • Pull Master Diff URL: ## Description This is a follow up of adding HTML to multiplechoice question MDL-24594. In 1.9 users can put image in Cloze multiplechoice answers so we should implement this in 2.0.. The HTML editor is already there for the questiontext that is used to generate the subquestions answers. This will need a very specific code given that the question images of the main cloze question will be used answers of the child multiplechoice questions. This could not be implement in the select element classic multichoice. The coding will be more complex and necessitates a distinct project. ## Attachments 1. cloze-with-image.xml 0.5 kB UMass Amherst Instructional Media Lab 2. questions-T100-import1.9mix-20110314-1202.xml 52 kB Pierre Pichet 3. questions-T1-export 26511 selection-20130424-2301.xml 477 kB Pierre Pichet 4. questions-T-26511_with_or_no_images-20130604-2349.xml 93 kB Pierre Pichet 5. questions-T-26511-Default for Mis.xml 46 kB Pierre Pichet 1. all_images.jpg 202 kB 249 kB 3. screenshot-1.jpg 75 kB 4. screenshot-2.jpg 132 kB 5. screenshot-3.jpg 68 kB 1 Cloze question and subquestions should be HTML clean Development in progress Pierre Pichet ## Activity Hide Pierre Pichet added a comment - - edited Tim The problem is the following. If I create a Cloze question with one image in one multiple choice option and put in the question text. The database will contain question id 1, question text <p> </p> <p>Cette question comporte du texte dans lequel on a intégré une première <img title="rr" src="http://www.moodle.uqam.ca/coursv2/file.php/197/irose.jpg" border="0" alt="rr" hspace="0" vspace="0" width="80" height="60" /> sous-question à choix multiples {#1} ;</p> then a second child question 2(parent id 1 ) questiontext (in the actual code the child question is not considered as HTML) {1:MULTICHOICE_V:<img style="margin: 0px; border: 0pt none;" title="rr" src="http://132.208.141.198/moodlehg/draftfile.php/13/user/draft/708801269/IORANGE.jpg" alt="rr" width="80" height="60" />#Feedback pour cette mauvaise réponse~Une autre mauvaise réponse#Feedback pour cette autre mauvaise réponse~=Bonne réponse#Feedback pour la bonne réponse~%50%Réponse qui vaut la moitié des points#Feedback pour la question qui vaut la moitié des points} And finally an answer of child question 2 will contain (unconverted) <img style="margin: 0px; border: 0pt none;" title="rr" src="http://132.208.141.198/moodlehg/draftfile.php/13/user/draft/708801269/IORANGE.jpg" alt="rr" width="80" height="60" /> If I implement the actual code 1 IORANGE.jpg reference in question_files table will be in 'question' 'questiontext' and a second one will be in 'question' 'answertext' with the answer id. The two in the same context. Here I understand that I don't understand sufficiently this hash structure to know if there will be only 1 copy (user/draft) or 3 copies (user/draft, question/questiontext and one question/answertext) of IORANGE.jpg in the moodledata. Show Pierre Pichet added a comment - - edited Tim The problem is the following. If I create a Cloze question with one image in one multiple choice option and put in the question text. The database will contain question id 1, question text <p> </p> <p>Cette question comporte du texte dans lequel on a intégré une première <img title="rr" src="http://www.moodle.uqam.ca/coursv2/file.php/197/irose.jpg" border="0" alt="rr" hspace="0" vspace="0" width="80" height="60" /> sous-question à choix multiples {#1} ;</p> then a second child question 2(parent id 1 ) questiontext (in the actual code the child question is not considered as HTML) {1:MULTICHOICE_V:<img style="margin: 0px; border: 0pt none;" title="rr" src="http://132.208.141.198/moodlehg/draftfile.php/13/user/draft/708801269/IORANGE.jpg" alt="rr" width="80" height="60" />#Feedback pour cette mauvaise réponse~Une autre mauvaise réponse#Feedback pour cette autre mauvaise réponse~=Bonne réponse#Feedback pour la bonne réponse~%50%Réponse qui vaut la moitié des points#Feedback pour la question qui vaut la moitié des points} And finally an answer of child question 2 will contain (unconverted) <img style="margin: 0px; border: 0pt none;" title="rr" src="http://132.208.141.198/moodlehg/draftfile.php/13/user/draft/708801269/IORANGE.jpg" alt="rr" width="80" height="60" /> If I implement the actual code 1 IORANGE.jpg reference in question_files table will be in 'question' 'questiontext' and a second one will be in 'question' 'answertext' with the answer id. The two in the same context. Here I understand that I don't understand sufficiently this hash structure to know if there will be only 1 copy (user/draft) or 3 copies (user/draft, question/questiontext and one question/answertext) of IORANGE.jpg in the moodledata. Hide Pierre Pichet added a comment - Some time later... I understand that there is only one copy of the file of a given hash name whatever name is used to identify it in the code (i.e. the name given when the file (i.e. ivert.jpg ) was include using the API file interface. If the hash is '6155eeb0b04b95444b876f53dd9611c786dba061' it will be stored as moodledata/filedir/61/55/6155eeb0b04b95444b876f53dd9611c786dba061 the records files data for this can be something like 25, '6155eeb0b04b95444b876f53dd9611c786dba061', '62260892500cce17ca1a35ff866926ad63d169bc', 21, 'question', 'questiontext', 16, '/', 'ivert.jpg', , 8818, 'image/jpeg', 0, '', '', '', 1297870972, 1297870972, 0 35, '6155eeb0b04b95444b876f53dd9611c786dba061', '7e4243b4f42fd487c068b3b1943c0ad839d97b2a', 13, 'user', 'draft', 23834229, '/', 'iivert', 2, 8818, 'document/unknown', 0, '', 'Admin User', 'allrightsreserved', 1297913037, 1297913037, 0 41, '6155eeb0b04b95444b876f53dd9611c786dba061', 'd0935e55d39d0a371cbc9fab9349b569843549e8', 37, 'question', 'answerfeedback', 62, '/', 'iivert', 2, 8818, 'document/unknown', 0, '', 'Admin User', 'allrightsreserved', 1297913037, 1297913037, 0 So let's proceed although my comment on MDL-24594 on 'answertext' and answer['text'] remained before going further. Show Pierre Pichet added a comment - Some time later... I understand that there is only one copy of the file of a given hash name whatever name is used to identify it in the code (i.e. the name given when the file (i.e. ivert.jpg ) was include using the API file interface. If the hash is '6155eeb0b04b95444b876f53dd9611c786dba061' it will be stored as moodledata/filedir/61/55/6155eeb0b04b95444b876f53dd9611c786dba061 the records files data for this can be something like 25, '6155eeb0b04b95444b876f53dd9611c786dba061', '62260892500cce17ca1a35ff866926ad63d169bc', 21, 'question', 'questiontext', 16, '/', 'ivert.jpg', , 8818, 'image/jpeg', 0, '', '', '', 1297870972, 1297870972, 0 35, '6155eeb0b04b95444b876f53dd9611c786dba061', '7e4243b4f42fd487c068b3b1943c0ad839d97b2a', 13, 'user', 'draft', 23834229, '/', 'iivert', 2, 8818, 'document/unknown', 0, '', 'Admin User', 'allrightsreserved', 1297913037, 1297913037, 0 41, '6155eeb0b04b95444b876f53dd9611c786dba061', 'd0935e55d39d0a371cbc9fab9349b569843549e8', 37, 'question', 'answerfeedback', 62, '/', 'iivert', 2, 8818, 'document/unknown', 0, '', 'Admin User', 'allrightsreserved', 1297913037, 1297913037, 0 So let's proceed although my comment on MDL-24594 on 'answertext' and answer ['text'] remained before going further. Hide Tim Hunt added a comment - Hmm. Yes. That is tricky. Not sure of the best solution at the moment. Is it possible to just keep all the files in the questiontext file area for the multianswer question? That might be the simplest thing, because it corresponds most closely with what happens on the editing form. Show Tim Hunt added a comment - Hmm. Yes. That is tricky. Not sure of the best solution at the moment. Is it possible to just keep all the files in the questiontext file area for the multianswer question? That might be the simplest thing, because it corresponds most closely with what happens on the editing form. Hide Pierre Pichet added a comment - "all the files in the questiontext file area" This will also simplify the import-export process. and the print_question_display that produced the answer display is the multianswer/questiontype.php function so we can rebuild the answers with the correct settings. So back to work after some exams "manual" grading. Show Pierre Pichet added a comment - "all the files in the questiontext file area" This was my solution before reading your comments. This will also simplify the import-export process. and the print_question_display that produced the answer display is the multianswer/questiontype.php function so we can rebuild the answers with the correct settings. So back to work after some exams "manual" grading. Hide Pierre Pichet added a comment - Finaaly I try to use a more standard method i.e. using the multiplechoice/questiontype.php to handle the coding of much of the coding with the exceptiob of the print and display. I have a partial succes i.e. the images a saved correclty but their display is only partial. This seems to be conncted to the $a->text = quiz_rewrite_question_urls($mcanswer->answer, 'pluginfile.php', $context->id, 'question', 'answertext',array($state->attempt ,$state->question ),$mcanswer->id); and more specifically to the array( $state->attempt ,$state->question ), parameters which I need to explore the code before going further. This bug seems like as exam on the new file API Show Pierre Pichet added a comment - Finaaly I try to use a more standard method i.e. using the multiplechoice/questiontype.php to handle the coding of much of the coding with the exceptiob of the print and display. I have a partial succes i.e. the images a saved correclty but their display is only partial. This seems to be conncted to the $a->text = quiz_rewrite_question_urls($mcanswer->answer, 'pluginfile.php', $context->id, 'question', 'answertext',array($state->attempt ,$state->question ),$mcanswer->id); and more specifically to the array( $state->attempt ,$state->question ), parameters which I need to explore the code before going further. This bug seems like as exam on the new file API Hide Pierre Pichet added a comment - The answers and feedback image show correctly. I add a not so restrictive condition to file access. function check_file_access($question,$state, $options,$contextid, $component,$filearea, $args) { if ($component == 'question' && $filearea == 'answerfeedback') { return$options->feedback ; } else if ($component == 'question' &&$filearea == 'answertext') { return true ;// array_key_exists($itemid,$question->options->questions); } else { return parent::check_file_access($question,$state, $options,$contextid, $component,$filearea, $args); } } As I cannot easily use the answer->id, at least I could change it to test the question->id like questiontext. Show Pierre Pichet added a comment - The answers and feedback image show correctly. I add a not so restrictive condition to file access. function check_file_access($question, $state,$options, $contextid,$component, $filearea,$args) { if ($component == 'question' &&$filearea == 'answerfeedback') { return $options->feedback ; } else if ($component == 'question' && $filearea == 'answertext') { return true ;// array_key_exists($itemid,$question->options->questions); } else { return parent::check_file_access($question, $state,$options, $contextid,$component, $filearea,$args); } } As I cannot easily use the answer->id, at least I could change it to test the question->id like questiontext. Hide Pierre Pichet added a comment - Tim, Things are going nicely. However I have a problem when I move the questions in another context as the questionlib question_move_questions_to_category although it moves the question files do not move the subquestion files even if it changes the category of the subquestions. I need to add the following code to transfer correctly the images of the sub multichoice. function question_move_questions_to_category($questionids,$newcategoryid) { global $DB,$QTYPES; $newcontextid =$DB->get_field('question_categories', 'contextid', array('id' => $newcategoryid)); list($questionidcondition, $params) =$DB->get_in_or_equal($questionids); $questions = $DB->get_records_sql(" SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.id$questionidcondition ", $params); foreach ($questions as $question) { if ($newcontextid != $question->contextid) { $QTYPES[$question->qtype]->move_files($question->id, $question->contextid,$newcontextid); $subquestions =$DB->get_records_sql(" SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.parent $questionidcondition ",$params); foreach ($subquestions as$question) { if ($newcontextid !=$question->contextid) { $QTYPES[$question->qtype]->move_files($question->id, $question->contextid, $newcontextid); } } } // Move the questions themselves. $DB->set_field_select('question', 'category', $newcategoryid, "id$questionidcondition", $params); // Move any subquestions belonging to them. $DB->set_field_select('question', 'category', $newcategoryid, "parent$questionidcondition", $params); // TODO Deal with datasets. return true; Any comment on the code will be appreciate. This remind me that I have also an open bug on datasets Show Pierre Pichet added a comment - Tim, Things are going nicely. However I have a problem when I move the questions in another context as the questionlib question_move_questions_to_category although it moves the question files do not move the subquestion files even if it changes the category of the subquestions. I need to add the following code to transfer correctly the images of the sub multichoice. function question_move_questions_to_category($questionids, $newcategoryid) { global$DB, $QTYPES;$newcontextid = $DB->get_field('question_categories', 'contextid', array('id' =>$newcategoryid)); list($questionidcondition,$params) = $DB->get_in_or_equal($questionids); $questions =$DB->get_records_sql(" SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.id $questionidcondition ",$params); foreach ($questions as$question) { if ($newcontextid !=$question->contextid) { $QTYPES[$question->qtype]->move_files($question->id,$question->contextid, $newcontextid);$subquestions = $DB->get_records_sql(" SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.parent$questionidcondition ", $params); foreach ($subquestions as $question) { if ($newcontextid != $question->contextid) {$QTYPES[$question->qtype]->move_files($question->id, $question->contextid,$newcontextid); } } } // Move the questions themselves. $DB->set_field_select('question', 'category',$newcategoryid, "id $questionidcondition",$params); // Move any subquestions belonging to them. $DB->set_field_select('question', 'category',$newcategoryid, "parent $questionidcondition",$params); // TODO Deal with datasets. return true; Any comment on the code will be appreciate. This remind me that I have also an open bug on datasets Hide Tim Hunt added a comment - I don't think that code is right. I think that instead we should either: 1. Put code like that inside the qtype_multianswer::move_files method; or 2. Change the first query in the function so that it does $questions =$DB->get_records_sql(" SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.id $questionidcondition OR q.parent$questionidcondition", array_merge($params,$params)); and then you don't need to change the foreach loop at all Actually, 2. is right, because it is consistent with the two $DB->set_field_select calls that come afterwards. Show Tim Hunt added a comment - I don't think that code is right. I think that instead we should either: 1. Put code like that inside the qtype_multianswer::move_files method; or 2. Change the first query in the function so that it does$questions = $DB->get_records_sql( " SELECT q.id, q.qtype, qc.contextid FROM {question} q JOIN {question_categories} qc ON q.category = qc.id WHERE q.id$questionidcondition OR q.parent $questionidcondition" , array_merge($params, $params)); and then you don't need to change the foreach loop at all Actually, 2. is right, because it is consistent with the two$DB->set_field_select calls that come afterwards. Hide Pierre Pichet added a comment - " because it is consistent with the two $DB->set_field_select calls that come afterwards." Solution 1 to put the code inside the questiontype seems to me more in-line with the plug-in philosophy that a question data should not be done "externally" unless we are sure that this does not broke anything unless we set restrictions on questiontype features which will be difficult before finishing the new engine code. Solution 2 setting of category id means that questions should be completely independent of the category setting which is not a "written constraint". Personnaly I prefer solution 1 which could mean to also change the way we modified the category setting by a call to a questiontype function. Using option 1 or 2 will modify the way I will build the move dataset code. Show Pierre Pichet added a comment - " because it is consistent with the two$DB->set_field_select calls that come afterwards." Solution 1 to put the code inside the questiontype seems to me more in-line with the plug-in philosophy that a question data should not be done "externally" unless we are sure that this does not broke anything unless we set restrictions on questiontype features which will be difficult before finishing the new engine code. Solution 2 setting of category id means that questions should be completely independent of the category setting which is not a "written constraint". Personnaly I prefer solution 1 which could mean to also change the way we modified the category setting by a call to a questiontype function. Using option 1 or 2 will modify the way I will build the move dataset code. Hide Pierre Pichet added a comment - Test moving with your suggestion, works correctly (as usual ). Backup and restore seems working also. So need code cleaning, other testing and time to do it, So early next week ... Show Pierre Pichet added a comment - Test moving with your suggestion, works correctly (as usual ). Backup and restore seems working also. So need code cleaning, other testing and time to do it, So early next week ... Hide Pierre Pichet added a comment - My more complex database code was the less complex code to apply and to test at 11H30 PM Show Pierre Pichet added a comment - My more complex database code was the less complex code to apply and to test at 11H30 PM Hide Pierre Pichet added a comment - It won't be early this week I have succeeded in XML import export BUT discover that the files table was full on non-used files. I am modifying the decode-saving process of the main question and subquestions to include at the rigth place the file saving for subquestion, answers and feedback of the images that are all in the main questiontext. I have a first solution for xml import answertext where files already exists (i.e.['files'] is not empty that should work for editing where ['itemid'] is not empty.. Show Pierre Pichet added a comment - It won't be early this week I have succeeded in XML import export BUT discover that the files table was full on non-used files. I am modifying the decode-saving process of the main question and subquestions to include at the rigth place the file saving for subquestion, answers and feedback of the images that are all in the main questiontext. I have a first solution for xml import answertext where files already exists (i.e. ['files'] is not empty that should work for editing where ['itemid'] is not empty.. Hide Pierre Pichet added a comment - The code flow is that the satus of either HTML with files should be set by the embedded_cloze_qtype->qtype_multianswer_extract_question() function which return the parameters (like answer) either as an array [text][forma][itemid] or as a non array answer. The embedded_cloze_qtype->save_question and embedded_cloze_qtype->save_question_options or the format->import applies to each components of the subquestions the right data [itemid] or [files] before saving them. In format import this gives something like this as files already exist foreach($qo->options->questions as$wrapped) { foreach($wrapped->answer as$key => $answer) { if(is_array($answer)){ foreach($qo->questiontextfiles as$file ){ if(preg_match('/(@@PLUGINFILE@@\/'.$file->name.')/',$answer['text'])){ $wrapped->answer[$key]['files'][]=$file ; } } } } This should be the same in embedded_cloze_qtype->save_question_options... More news later Show Pierre Pichet added a comment - The code flow is that the satus of either HTML with files should be set by the embedded_cloze_qtype->qtype_multianswer_extract_question() function which return the parameters (like answer) either as an array [text] [forma] [itemid] or as a non array answer. The embedded_cloze_qtype->save_question and embedded_cloze_qtype->save_question_options or the format->import applies to each components of the subquestions the right data [itemid] or [files] before saving them. In format import this gives something like this as files already exist foreach($qo->options->questions as $wrapped) { foreach($wrapped->answer as $key =>$answer) { if(is_array($answer)){ foreach($qo->questiontextfiles as $file ){ if(preg_match('/(@@PLUGINFILE@@\/'.$file->name.')/',$answer['text'])){$wrapped->answer[$key]['files'][]=$file ; } } } } This should be the same in embedded_cloze_qtype->save_question_options... More news later Hide Pierre Pichet added a comment - Tim, The questiontype->move_files() move all files in one context to another one. What I need is a function to move some of the files already in question questiontext to the specific context where they will be used. This is not really moving i.e. no delete in main multianswer question question text but create a new link in for example question answertext or question feedbacktext. I could retrieve the files form the question questiontext area and apply them to each answer element that used them as I do on import but is there a more simple way. In file storage lib the function seems to always transfer all the files from one context to the other. I understand that in this case as we will need somewhere in the multianswer all the files in the multianswer draft area that were all moved when saving in the quuestion questiontext, there should be no delete when "virtually" moving the files in one or more contexts. Show Pierre Pichet added a comment - Tim, The questiontype->move_files() move all files in one context to another one. What I need is a function to move some of the files already in question questiontext to the specific context where they will be used. This is not really moving i.e. no delete in main multianswer question question text but create a new link in for example question answertext or question feedbacktext. I could retrieve the files form the question questiontext area and apply them to each answer element that used them as I do on import but is there a more simple way. In file storage lib the function seems to always transfer all the files from one context to the other. I understand that in this case as we will need somewhere in the multianswer all the files in the multianswer draft area that were all moved when saving in the quuestion questiontext, there should be no delete when "virtually" moving the files in one or more contexts. Hide Pierre Pichet added a comment - Sorry if the precedent comment is not as clear as it should be Show Pierre Pichet added a comment - Sorry if the precedent comment is not as clear as it should be Hide Pierre Pichet added a comment - Or I use the actual movefiles function as this is just supplementary records in "files" database table. Show Pierre Pichet added a comment - Or I use the actual movefiles function as this is just supplementary records in "files" database table. Hide Pierre Pichet added a comment - TIm I have a code solution that can create using the edit_multianswer_form or xml format, a multianswer question where multiple choice vertical or horizontal answers can include images. The answerfeedback can use image for all question types although the image cannot be shown in the actual pop-up window (this is a specific bug ). The actual code repeat all the files in each area (question questiontext, question answertext and question feedbacktext) if there are images in the coresponding answer or feedback. This create more records in the files table than necessary. However when the question is deleted, all those records are deleted. Si I can 1. finish testing and clean the code of all print_r etc and commit as it is now. 2. solve the file handling then commit but inactivate the images in feedback for question types other than MCV or MCH 3. solve the file handling and the feedback pop-up and and commit a "completely" finish solution 4. or ... Show Pierre Pichet added a comment - TIm I have a code solution that can create using the edit_multianswer_form or xml format, a multianswer question where multiple choice vertical or horizontal answers can include images. The answerfeedback can use image for all question types although the image cannot be shown in the actual pop-up window (this is a specific bug ). The actual code repeat all the files in each area (question questiontext, question answertext and question feedbacktext) if there are images in the coresponding answer or feedback. This create more records in the files table than necessary. However when the question is deleted, all those records are deleted. Si I can 1. finish testing and clean the code of all print_r etc and commit as it is now. 2. solve the file handling then commit but inactivate the images in feedback for question types other than MCV or MCH 3. solve the file handling and the feedback pop-up and and commit a "completely" finish solution 4. or ... Hide Pierre Pichet added a comment - AS this is an improvement and not a bug, I will take the time necessary to handle moving individual file from one context to another (not real moving in the new file API) so to limit the number of records in files table. More news later Show Pierre Pichet added a comment - AS this is an improvement and not a bug, I will take the time necessary to handle moving individual file from one context to another (not real moving in the new file API) so to limit the number of records in files table. More news later Hide Pierre Pichet added a comment - Tim, I think that the more useable way to do this is to use the images in the draft_area item for questiontext as I have done in the different areas related to either question answertext and question feedbacktext. This will give us more records in th files table but the code will be safe... This is more or less the solution that is suggested in filelib.php function file_save_draft_area_files($draftitemid,$contextid, $component,$filearea, $itemid, array$options=null, $text=null,$forcehttps=false) { ... line 714 // note: do not purge the draft area - we clean up areas later in cron, // the reason is that user might press submit twice and they would loose the files, // also sometimes we might want to use hacks that save files into two different areas So I clean the code, do more tests and prepare the commit Show Pierre Pichet added a comment - Tim, I think that the more useable way to do this is to use the images in the draft_area item for questiontext as I have done in the different areas related to either question answertext and question feedbacktext. This will give us more records in th files table but the code will be safe... This is more or less the solution that is suggested in filelib.php function file_save_draft_area_files($draftitemid,$contextid, $component,$filearea, $itemid, array$options=null, $text=null,$forcehttps=false) { ... line 714 // note: do not purge the draft area - we clean up areas later in cron, // the reason is that user might press submit twice and they would loose the files, // also sometimes we might want to use hacks that save files into two different areas So I clean the code, do more tests and prepare the commit Hide Tim Hunt added a comment - That sounds like a reasonable plan. I look forwards to reviewing the code. Show Tim Hunt added a comment - That sounds like a reasonable plan. I look forwards to reviewing the code. Hide Pierre Pichet added a comment - The images can also been shown on pop-up feedback for all question types (i.e multiplechoice select, shortaswer and numerical) as in 1.9. Show Pierre Pichet added a comment - The images can also been shown on pop-up feedback for all question types (i.e multiplechoice select, shortaswer and numerical) as in 1.9. Hide Pierre Pichet added a comment - I should be able to put everything on commits before the weekend. Show Pierre Pichet added a comment - I should be able to put everything on commits before the weekend. Hide Tim Hunt added a comment - That would be great. I can't promise to review it this weekend, or indeed before next Wednesday, but I will try to do it shortly after that. Show Tim Hunt added a comment - That would be great. I can't promise to review it this weekend, or indeed before next Wednesday, but I will try to do it shortly after that. Hide Pierre Pichet added a comment - OK let say that I postpone my delay to before next Wednesday so I can do more testing. Show Pierre Pichet added a comment - OK let say that I postpone my delay to before next Wednesday so I can do more testing. Hide Pierre Pichet added a comment - seems to contain everything for images in Cloze vertical and horizontal dispaly as in feedback of all the question types multiplechoice variants, shortanswer and numerical. I have test by creating a question using all these types. Editing the question as a new one. Moving the questions in another context Exporting the questions in XML format Importing them in XML format (incidently the files from 1,9 do not stored the images with the exception of the question image.) Previewing, Putting the questions in a quiz. Doing attempt as a student. Making a backup of the course mostly the quiz and attampts. Doing a restore to another course Testing that the attempt data was good In all these tests the images follow Testing that deleting the question, delete all the files records related to this question as the question and answers related records. So I let you continue ... Show Pierre Pichet added a comment - The commit https://github.com/ppichet/moodle/commit/a6deba0ebb4ff168a4ea737bf37af118a42f462a seems to contain everything for images in Cloze vertical and horizontal dispaly as in feedback of all the question types multiplechoice variants, shortanswer and numerical. I have test by creating a question using all these types. Editing the question as a new one. Moving the questions in another context Exporting the questions in XML format Importing them in XML format (incidently the files from 1,9 do not stored the images with the exception of the question image.) Previewing, Putting the questions in a quiz. Doing attempt as a student. Making a backup of the course mostly the quiz and attampts. Doing a restore to another course Testing that the attempt data was good In all these tests the images follow Testing that deleting the question, delete all the files records related to this question as the question and answers related records. So I let you continue ... Hide Pierre Pichet added a comment - xml file for export import tests Show Pierre Pichet added a comment - xml file for export import tests Hide Pierre Pichet added a comment - The main question used to test Show Pierre Pichet added a comment - The main question used to test Hide UMass Amherst Instructional Media Lab added a comment - Is there any further progress on this "improvement"? We agree with Respondus that this feels more like a bug than an improvement: we have several Cloze questions with images in them, but we are unable to export them or backup the questions because the images get dropped from the Moodle XML file format. This means that once we add an image to a Cloze question, we cannot subsequently move that question from one course to another course – backing up and restoring the course also does not work because the images disappear in the restored course. I am attaching a Moodle XML file containing the code for a simple Cloze question with an inlined image. The image data is missing from the XML file, so when you import this XML file into another course the image is broken. Show UMass Amherst Instructional Media Lab added a comment - Is there any further progress on this "improvement"? We agree with Respondus that this feels more like a bug than an improvement: we have several Cloze questions with images in them, but we are unable to export them or backup the questions because the images get dropped from the Moodle XML file format. This means that once we add an image to a Cloze question, we cannot subsequently move that question from one course to another course – backing up and restoring the course also does not work because the images disappear in the restored course. I am attaching a Moodle XML file containing the code for a simple Cloze question with an inlined image. The image data is missing from the XML file, so when you import this XML file into another course the image is broken. Hide UMass Amherst Instructional Media Lab added a comment - Cloze q with image, but image data is missing from the exported Moodle XML file. Show UMass Amherst Instructional Media Lab added a comment - Cloze q with image, but image data is missing from the exported Moodle XML file. Hide Pierre Pichet added a comment - Tim, I understand that you have a quite heavy case load for the following days . Next week I am back on Moodle and UQAM autumn courses and I will review my march proposal as code have changed even recently for multianswer and also in the import, backup and restore process. Hopefully this sould be available in the first days of september. Show Pierre Pichet added a comment - Tim, I understand that you have a quite heavy case load for the following days . Next week I am back on Moodle and UQAM autumn courses and I will review my march proposal as code have changed even recently for multianswer and also in the import, backup and restore process. Hopefully this sould be available in the first days of september. Hide Tim Hunt added a comment - OK. I am on holiday 2nd to 9th September, so this will probably have to wait until I get back. Show Tim Hunt added a comment - OK. I am on holiday 2nd to 9th September, so this will probably have to wait until I get back. Hide Tim Hunt added a comment - This bug is marked 'Waiting for peer review, but I cannot immediately see what I am meant to be reviewing. Show Tim Hunt added a comment - This bug is marked 'Waiting for peer review, but I cannot immediately see what I am meant to be reviewing. Hide UMass Amherst Instructional Media Lab added a comment - Hi Tim, Pierre, Is there any progress on this issue? We are about to migrate from 2.0.5 to 2.1.2 and we see that this is still a bug in 2.1.2. As we mention above, we have several faculty clients who have quizzes on 2.0.5 that have images in their cloze question types, and this issue makes it impossible for them to move their quiz questions from one course to another course. Thanks! Take care, hari Instructional Media Lab UMass Amherst Show UMass Amherst Instructional Media Lab added a comment - Hi Tim, Pierre, Is there any progress on this issue? We are about to migrate from 2.0.5 to 2.1.2 and we see that this is still a bug in 2.1.2. As we mention above, we have several faculty clients who have quizzes on 2.0.5 that have images in their cloze question types, and this issue makes it impossible for them to move their quiz questions from one course to another course. Thanks! Take care, hari Instructional Media Lab UMass Amherst Hide Pierre Pichet added a comment - What are your time schedule so that we could hopefully synchronize The solution https://github.com/ppichet/moodle/commit/a6deba0ebb4ff168a4ea737bf37af118a42f462a was working in march but needs to be merged with modifications and new testings as the master has changed since. Show Pierre Pichet added a comment - "We are about to migrate" What are your time schedule so that we could hopefully synchronize The solution https://github.com/ppichet/moodle/commit/a6deba0ebb4ff168a4ea737bf37af118a42f462a was working in march but needs to be merged with modifications and new testings as the master has changed since. Hide Pierre Pichet added a comment - Tim, Given the modifications related to the new engine, I should somehow apply the march code to 2,0 which imply the XML format then do the merge with the actual master. The images are already saved correctly in the questiontext. The problem is to save them again as part of the subquestions when decoding the question text. I will set two simultaneous master and 2,0 moodle site to be sure that the 2,0 code is optimized for merging in master. Show Pierre Pichet added a comment - Tim, Given the modifications related to the new engine, I should somehow apply the march code to 2,0 which imply the XML format then do the merge with the actual master. The images are already saved correctly in the questiontext. The problem is to save them again as part of the subquestions when decoding the question text. I will set two simultaneous master and 2,0 moodle site to be sure that the 2,0 code is optimized for merging in master. Hide UMass Amherst Instructional Media Lab added a comment - Hi Pierre, As for a timeline, we are currently evaluating 2.1.2 and deciding whether to move from 2.0.5 to 2.1 in January or over the summer of 2012. We have several courses on 2.0.5 that have images in their questions – some couple hundred of these questions are Embedded Answer (Cloze) type questions with images in the questions. These questions are currently breaking our ability to export/import quizzes from course to course, or even exporting/importing entire courses because the images get lost in transition. Is it possible for this fix to get into 2.1.3 and then backported to 2.1.2 and/or 2.0.5? Thanks Pierre and Tim! Take care, hari Instructional Media Lab UMass Amherst Show UMass Amherst Instructional Media Lab added a comment - Hi Pierre, As for a timeline, we are currently evaluating 2.1.2 and deciding whether to move from 2.0.5 to 2.1 in January or over the summer of 2012. We have several courses on 2.0.5 that have images in their questions – some couple hundred of these questions are Embedded Answer (Cloze) type questions with images in the questions. These questions are currently breaking our ability to export/import quizzes from course to course, or even exporting/importing entire courses because the images get lost in transition. Is it possible for this fix to get into 2.1.3 and then backported to 2.1.2 and/or 2.0.5? Thanks Pierre and Tim! Take care, hari Instructional Media Lab UMass Amherst Hide UMass Amherst Instructional Media Lab added a comment - Also Pierre, we tried to get your proposed solution from the github repository but there were way too many changes in that source code to integrate into our installation, especially since we already had several other patches in place for an Oracle-related bug that got fixed in 2.0.5. Show UMass Amherst Instructional Media Lab added a comment - Also Pierre, we tried to get your proposed solution from the github repository but there were way too many changes in that source code to integrate into our installation, especially since we already had several other patches in place for an Oracle-related bug that got fixed in 2.0.5. Hide Pierre Pichet added a comment - "there were way too many changes in that source code" This why I wrote "to be sure that the 2,0 code is optimized for merging in master" I cannot promise anything in January , however I have only one course in winter so this will be solved hopefully before spring. We discussed yesterday of our ( Université du Québec à Montréal) moodle comity of moving from 1,9 to at least 2,2 and we concluded that we will do it when everything will have been really tested given the complexity of the new question engine and the file api . "really tested" has a more precise meaning "OU tested" Given all the local modifications our calendar could be January 2013 for some courses and a general deployment in autumn 2013. Show Pierre Pichet added a comment - "there were way too many changes in that source code" This why I wrote "to be sure that the 2,0 code is optimized for merging in master" I cannot promise anything in January , however I have only one course in winter so this will be solved hopefully before spring. We discussed yesterday of our ( Université du Québec à Montréal) moodle comity of moving from 1,9 to at least 2,2 and we concluded that we will do it when everything will have been really tested given the complexity of the new question engine and the file api . "really tested" has a more precise meaning "OU tested" Given all the local modifications our calendar could be January 2013 for some courses and a general deployment in autumn 2013. Hide Pierre Pichet added a comment - - edited Just a comment that I have started to merge with actual master. first tests are successfull. 1. Images can stored in main question text , multichoice answers and feedbacks. 2. questions preview correctly 3. questions can be moved to other categories 4. backup and restore quiz from courses tested OK 5. next: xml import export Show Pierre Pichet added a comment - - edited Just a comment that I have started to merge with actual master. first tests are successfull. 1. Images can stored in main question text , multichoice answers and feedbacks. 2. questions preview correctly 3. questions can be moved to other categories 4. backup and restore quiz from courses tested OK 5. next: xml import export Hide Tim Hunt added a comment - Thanks for the update. Sounds like it is going well. Do you think you will have time to peer-review MDL-30322? Show Tim Hunt added a comment - Thanks for the update. Sounds like it is going well. Do you think you will have time to peer-review MDL-30322 ? Hide Pierre Pichet added a comment - Import-export seems OK on up-to-date 2,2. More tests from 1,9 to 2,2 and between different installations are needed. Show Pierre Pichet added a comment - Import-export seems OK on up-to-date 2,2. More tests from 1,9 to 2,2 and between different installations are needed. Hide Pierre Pichet added a comment - - edited Tim, working on details. From 2,0 the elements (i.e. questiontiontext, feedback ) are defined as an array and the [format] has been defined as FORMAT_HTML. each wrapped questiontext is a fraction of the main questiontext so I proposed to set as $wrapped->generalfeedback['text'] = ''; $wrapped->generalfeedback['format'] = FORMAT_HTML; $wrapped->generalfeedback['itemid'] = ''; $wrapped->questiontext['text'] = $answerregs[0]; $wrapped->questiontext['format'] = $question->questiontext['format']; $wrapped->questiontext['itemid'] = $question->questiontext['itemid']; Using FORMAT_HTML or the questiontext['format'] are equivalent for 2,0 as the html editor is always set. But this could be different on xml import ($qo->questiontextformat). Show Pierre Pichet added a comment - - edited Tim, working on details. From 2,0 the elements (i.e. questiontiontext, feedback ) are defined as an array and the [format] has been defined as FORMAT_HTML. each wrapped questiontext is a fraction of the main questiontext so I proposed to set as $wrapped->generalfeedback['text'] = '';$wrapped->generalfeedback['format'] = FORMAT_HTML; $wrapped->generalfeedback['itemid'] = '';$wrapped->questiontext['text'] = $answerregs[0];$wrapped->questiontext['format'] = $question->questiontext['format'];$wrapped->questiontext['itemid'] = $question->questiontext['itemid']; Using FORMAT_HTML or the questiontext ['format'] are equivalent for 2,0 as the html editor is always set. But this could be different on xml import ($qo->questiontextformat). Hide Pierre Pichet added a comment - I have push a new version rebase today at https://github.com/ppichet/moodle/tree/MDL-26511-2 Seems to work correctly although there are so many options to test. Doing the testing, I noticed some minor features with numerical tolerance that can be set and applied to each individual answers since at least 1,9 although in the older versions, the first tolerance was applied to each answers. I will identify precisely and set the bug on return from a 2 weeks holiday in Dominican Republic ( I wish you could do something similar ) starting next sunday. My teaching load in winter will be lower so I will be able to increase my Moodle one. Show Pierre Pichet added a comment - I have push a new version rebase today at https://github.com/ppichet/moodle/tree/MDL-26511-2 Seems to work correctly although there are so many options to test. Doing the testing, I noticed some minor features with numerical tolerance that can be set and applied to each individual answers since at least 1,9 although in the older versions, the first tolerance was applied to each answers. I will identify precisely and set the bug on return from a 2 weeks holiday in Dominican Republic ( I wish you could do something similar ) starting next sunday. My teaching load in winter will be lower so I will be able to increase my Moodle one. Hide Pierre Pichet added a comment - - edited The import code from 1,9 is not working properly because the 1,9 export does not work for images references in the question text. Having completed the import-export for 2,0, I just tested if it works with 1,9 export. As usual it was somehow too late in the night ;( and I did not realize that I was using the same Firefox to do the 2 jobs so I had access to the files in the 1,9 versions... So although the 1,9 cloze code allow you to insert images in all parts of the subquestions, this work only if you stay in the same course or can access it when logged. We should then consider the MDL-26511 is specific to 2,0 and does not solve the 1,9 cloze handling of images. I don't know how the migration code handle this. Show Pierre Pichet added a comment - - edited Bad news. The import code from 1,9 is not working properly because the 1,9 export does not work for images references in the question text. Having completed the import-export for 2,0, I just tested if it works with 1,9 export. As usual it was somehow too late in the night ;( and I did not realize that I was using the same Firefox to do the 2 jobs so I had access to the files in the 1,9 versions... So although the 1,9 cloze code allow you to insert images in all parts of the subquestions, this work only if you stay in the same course or can access it when logged. We should then consider the MDL-26511 is specific to 2,0 and does not solve the 1,9 cloze handling of images. I don't know how the migration code handle this. Hide Tim Hunt added a comment - 1. Please try to avoid whitespace changes like https://github.com/ppichet/moodle/commit/214ca33590e9e394d7d461923db4897fde0807f7#L0L584 - it makes it harder to see what has really changed. 2. I assume question/type/multianswer/lib1.php should not exist, and that you will clean it up eventually. 3. Instead of making this change: https://github.com/ppichet/moodle/commit/214ca33590e9e394d7d461923db4897fde0807f7#L4L208 would it be better to change the multianswer qtype to correctly initialise everything that the numerical qtype needs? Show Tim Hunt added a comment - A few quick comments: 1. Please try to avoid whitespace changes like https://github.com/ppichet/moodle/commit/214ca33590e9e394d7d461923db4897fde0807f7#L0L584 - it makes it harder to see what has really changed. 2. I assume question/type/multianswer/lib1.php should not exist, and that you will clean it up eventually. 3. Instead of making this change: https://github.com/ppichet/moodle/commit/214ca33590e9e394d7d461923db4897fde0807f7#L4L208 would it be better to change the multianswer qtype to correctly initialise everything that the numerical qtype needs? Hide Pierre Pichet added a comment - - edited 1.Please try to avoid whitespace changes. So next time, code changes first and adding here a note on code checker... 2. This was set to ignore and I did not noticed that I badly select the file when doing the commit. 3.Instead of making this change:..would it be better to change the multianswer qtype to correctly initialise everything that the numerical qtype needs? In principle you are right. However this means reworking somehow the big preg of multianswer and I did not have the time to do it correctly as we should also rework the handling of tolerance. Adding this supplementary test about a possible empty array is not a bad test by itself and it removes the notice send by the debugger that I encounter because of a specific more than one answer in the numerical subquestion that I use to test for the MDL-26511. In all cases, there are other minor problems with numerical on which I will have to work in january. I just did a force update to include the correct lib file. I expect that this was the thing to do... Show Hide Pierre Pichet added a comment - The differences between this last version MDL-26511-2 and the MDL-26511 are not very important. It should be not too difficult to create the versions for the moodle 2,x versions where you want to apply this. However as there is no urgency, I could do in january the merging once this has been tested and put on master. Show Pierre Pichet added a comment - The differences between this last version MDL-26511 -2 and the MDL-26511 are not very important. It should be not too difficult to create the versions for the moodle 2,x versions where you want to apply this. However as there is no urgency, I could do in january the merging once this has been tested and put on master. Hide Tim Hunt added a comment - Removing the patch label, since there is not a current patch that needs peer review. Show Tim Hunt added a comment - Removing the patch label, since there is not a current patch that needs peer review. Hide Jean-Michel Vedrine added a comment - Hello Pierre, Just to warn you that MDL-37313 Moodle XML import format should use draft file areas, not arrays (currently waiting for integration) will have some consequences on this issue and will need that you rework part of your code. Show Jean-Michel Vedrine added a comment - Hello Pierre, Just to warn you that MDL-37313 Moodle XML import format should use draft file areas, not arrays (currently waiting for integration) will have some consequences on this issue and will need that you rework part of your code. Hide Pierre Pichet added a comment - Thanks for the comment and on your work on moodle. This was a first draft when things were not correctly settled in the new file handling which is not the best thing in 2,0... We had a quite difficult situation in Québec universities the last semesters but things are back to a more normal state. So I should be able to solve this bug among other ones. Show Pierre Pichet added a comment - Thanks for the comment and on your work on moodle. This was a first draft when things were not correctly settled in the new file handling which is not the best thing in 2,0... We had a quite difficult situation in Québec universities the last semesters but things are back to a more normal state. So I should be able to solve this bug among other ones. Hide Jean-Michel Vedrine added a comment - - edited Unfortunately I think that after the recent changes to the way Moodle XML qformat is handling files Pierre's code need important changes to work again But I wonder if we could return to using Tim's idea : "Is it possible to just keep all the files in the questiontext file area for the multianswer question? That might be the simplest thing, because it corresponds most closely with what happens on the editing form." Not only does this corresponds more closely to what happens on the editing form but I think this also simplify other places in the code. • In the renderer.php file all the renderers (including those of the subq) would use the same file area and itemid when calling format_text • during xml import/export it also match more closely what happen because all files are after the questiontext Of course maybe there are problems that I don't see, but it's worth exploring this idea. Show Jean-Michel Vedrine added a comment - - edited Unfortunately I think that after the recent changes to the way Moodle XML qformat is handling files Pierre's code need important changes to work again But I wonder if we could return to using Tim's idea : "Is it possible to just keep all the files in the questiontext file area for the multianswer question? That might be the simplest thing, because it corresponds most closely with what happens on the editing form." Not only does this corresponds more closely to what happens on the editing form but I think this also simplify other places in the code. In the renderer.php file all the renderers (including those of the subq) would use the same file area and itemid when calling format_text during xml import/export it also match more closely what happen because all files are after the questiontext Of course maybe there are problems that I don't see, but it's worth exploring this idea. Hide Pierre Pichet added a comment - The solution I had last year was working before they modified all the way to handle files. Your excellent work on file import allow to settle in many ways how to handlefiles. My last year proposal have the advantage to put the images where the subquestions expect they are. This should be the main cloze code objective if we want to not duplicate all the subquestion code in cloze. My main spring semester courses are finished (exam today). I have things to fix in calculateds first and I see elsewhere that among other things your are exploring Open university new questiontype that could render obsolete Cloze. Given coding proficiency and your knowledge about file handling among other things, you should be be able to handle this more faster than me. So feel free to assign this to you. Show Pierre Pichet added a comment - The solution I had last year was working before they modified all the way to handle files. Your excellent work on file import allow to settle in many ways how to handlefiles. My last year proposal have the advantage to put the images where the subquestions expect they are. This should be the main cloze code objective if we want to not duplicate all the subquestion code in cloze. My main spring semester courses are finished (exam today). I have things to fix in calculateds first and I see elsewhere that among other things your are exploring Open university new questiontype that could render obsolete Cloze. Given coding proficiency and your knowledge about file handling among other things, you should be be able to handle this more faster than me. So feel free to assign this to you. Hide Pierre Pichet added a comment - We should not modify the question code plug-in philosophy because the file handling is badly designed but patch the file hanfling so that is allows plug-in. File handling remains by large the Moodle 2.0 bad case. Show Pierre Pichet added a comment - We should not modify the question code plug-in philosophy because the file handling is badly designed but patch the file hanfling so that is allows plug-in. File handling remains by large the Moodle 2.0 bad case. Hide Pierre Pichet added a comment - However I will try your patch on MDL-38880 and see how it can be used to solve the MDL-26511 case. Show Pierre Pichet added a comment - However I will try your patch on MDL-38880 and see how it can be used to solve the MDL-26511 case. Hide Pierre Pichet added a comment - Good news. Updating the old MDL-26511 to actual master is working quite well i.e. images can be used in multichoice answer and feeback. some trimmings like correct answer remain. So I am coming up on this bug. As a test I will insert MDL-38880 patch. Show Pierre Pichet added a comment - Good news. Updating the old MDL-26511 to actual master is working quite well i.e. images can be used in multichoice answer and feeback. some trimmings like correct answer remain. So I am coming up on this bug. As a test I will insert MDL-38880 patch. Hide Jean-Michel Vedrine added a comment - Hello Pierre, • suppress all you changes to question/format/xml/format.php because they are no more necessary change line $wrapped->feedback["$answerindex"]['itemid'] = ''; to $wrapped->feedback["$answerindex"]['itemid'] = $text['itemid']; and lines $wrapped->answer["$answerindex"] = array( 'text' =>$wrapped->answer["$answerindex"], 'format' => FORMAT_HTML, 'itemid' => ''); to $wrapped->answer["$answerindex"] = array( 'text' =>$wrapped->answer["$answerindex"], 'format' => FORMAT_HTML, 'itemid' =>$text['itemid']); that way during import and also during question creation/edition draftfiles are considered as both part of the main question and of the subquestions (of course that will lead to some records duplication in mdl_file table but that doesn't waste too much space as the images data are no duplicated). Show Jean-Michel Vedrine added a comment - Hello Pierre, Looking at your code https://github.com/ppichet/moodle/commit/9200042144fd0e60d4f5ffdfa68fc4835f1affbc (I don't know if this is your latest version) I think it's easy to adapt your code to MDL-38880 : suppress all you changes to question/format/xml/format.php because they are no more necessary in question/type/multianswer/questiontype.php just change 2 lines in the qtype_multianswer_extract_question function so that itemid is set for answers and answers feedback change line $wrapped->feedback["$answerindex"]['itemid'] = ''; to $wrapped->feedback["$answerindex"]['itemid'] = $text['itemid']; and lines$wrapped->answer["$answerindex"] = array( 'text' =>$wrapped->answer["$answerindex"], 'format' => FORMAT_HTML, 'itemid' => ''); to$wrapped->answer["$answerindex"] = array( 'text' =>$wrapped->answer["$answerindex"], 'format' => FORMAT_HTML, 'itemid' =>$text['itemid']); that way during import and also during question creation/edition draftfiles are considered as both part of the main question and of the subquestions (of course that will lead to some records duplication in mdl_file table but that doesn't waste too much space as the images data are no duplicated). Hide Pierre Pichet added a comment - I have done just a manual addition of your code in rebuilding manually the MDL-26511 as I want to review the last year issue. MDL-38880 will be put on master before I will have completed my work on MDL-26511. On rebase things will set correctly. The setting of itemid is done when saving the question after the extraction. https://github.com/ppichet/moodle/commit/9200042144fd0e60d4f5ffdfa68fc4835f1affbc#L3R173 I need to review this because we could allow images on more questiontypes feedback but not answers (short, numerical) Show Pierre Pichet added a comment - Thanks for your suggestions. I have done just a manual addition of your code in rebuilding manually the MDL-26511 as I want to review the last year issue. MDL-38880 will be put on master before I will have completed my work on MDL-26511 . On rebase things will set correctly. The setting of itemid is done when saving the question after the extraction. https://github.com/ppichet/moodle/commit/9200042144fd0e60d4f5ffdfa68fc4835f1affbc#L3R173 I need to review this because we could allow images on more questiontypes feedback but not answers (short, numerical) Hide Jean-Michel Vedrine added a comment - - edited Hello Pierre, I was unsure that setting itemid when saving the question would works both for edition and import but you are right it seems to work quite well with the added benefit that you can choose to add it only if the answer text contains "draftfile.php". Your link remind me that I forgot to say I don't understand why you have a check_file_access function in your questiontype.php, surely this fonction belongs to the qtype_multianswer_question class so it should be in question.php isn't it ? But multianser code is complex so maybe there is something I don't understand. Show Jean-Michel Vedrine added a comment - - edited Hello Pierre, Thanks for the link. I was unsure that setting itemid when saving the question would works both for edition and import but you are right it seems to work quite well with the added benefit that you can choose to add it only if the answer text contains "draftfile.php". Your link remind me that I forgot to say I don't understand why you have a check_file_access function in your questiontype.php, surely this fonction belongs to the qtype_multianswer_question class so it should be in question.php isn't it ? But multianser code is complex so maybe there is something I don't understand. Hide Pierre Pichet added a comment - My actual proposal give the following result: Let's take a simple shortanswer in which we want to put an image in the feedback (images are allowed in the feedback) The initial questiontext is The capital of France is The main (parent) questiontext will become The capital of France is {#1} then the subquestion questiontext is {1:SHORTANSWER:%100%Paris#Congratulations!<img src="@@PLUGINFILE@@image.gif" alt:"image".../>} Congratulations!<img src="@@PLUGINFILE@@image.gif" alt:"image".../ In the data base files there are 8 references to image.gif 2 filearea draft . and image.gif 2 questiontext itemid 133 (i.e. main question id) 2 questiontext itemid 134 subquestion id When the question is reedit the {#1} in the question text is replaced by the sub questiontext When the question is used the link is done through the answerfeedback filearea data. The proposal will then be extended to all subquestions (short, numerical, multiplechoices) answer feedback and to multiplechoice_V and multiplechoice_H . The validation will have to check that the users don't put images in short, numerical, multiplechoiceselect answers. The image rendering in the feedbacks is not solved for all cases actually. Show Hide Pierre Pichet added a comment - Tim, I solve the image rendering problem in feedback. However when adding images the 'blue field' containing the question is not sufficient. Where (or what) is the parameter that control the question space (length) display that is allowed by (quiz or preview) renderer to the question ? Show Pierre Pichet added a comment - Tim, I solve the image rendering problem in feedback. However when adding images the 'blue field' containing the question is not sufficient. Where (or what) is the parameter that control the question space (length) display that is allowed by (quiz or preview) renderer to the question ? Hide Tim Hunt added a comment - When I try to import the sample file, questions-T100-import1.9mix-20110314-1202.xml, I get an error: Field 'version' doesn't have a default value INSERT INTO question (qtype,questiontext,generalfeedback,defaultmark,name,questiontextformat,generalfeedbackformat,penalty,category,stamp,createdby,timecreated,modifiedby,timemodified) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?) I don't have time to work out why yet. Sorry, I will try to look at this later. Show Tim Hunt added a comment - When I try to import the sample file, questions-T100-import1.9mix-20110314-1202.xml, I get an error: Field 'version' doesn't have a default value INSERT INTO question (qtype,questiontext,generalfeedback,defaultmark,name,questiontextformat,generalfeedbackformat,penalty,category,stamp,createdby,timecreated,modifiedby,timemodified) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?) I don't have time to work out why yet. Sorry, I will try to look at this later. Hide Pierre Pichet added a comment - Sorry my github is not updated to my actual experimental version. I will put images that illustrate the problem and update the github. Show Pierre Pichet added a comment - Sorry my github is not updated to my actual experimental version. I will put images that illustrate the problem and update the github. Hide Pierre Pichet added a comment - The problem is related to the HTML editor which include <pre> and <p> when a file is included A simple question without image will look as Los Angeles: {1:MULTICHOICE_V:=California2#OK~Arizona#Wrong} with an image its is changed to Los Angeles: {1:MULTICHOICE_V:=California #OK~Arizona#Wrong} which scramble all the display as the db answer is California When doing it with careful handling I succeeded to a valid and correct display. Show Pierre Pichet added a comment - The problem is related to the HTML editor which include <pre> and <p> when a file is included A simple question without image will look as <pre>Los Angeles: {1:MULTICHOICE_V:=California2#OK~Arizona#Wrong}<br /><br /></pre> with an image its is changed to <pre>Los Angeles: {1:MULTICHOICE_V:=California </pre> <p><img src="http://132.208.141.198/moodle_w/draftfile.php/5/user/draft/271545410/xeo4%20%281%29.gif" alt="" width="30" height="30" /></p> <pre>#OK~Arizona#Wrong}</pre> which scramble all the display as the db answer is California</pre> <p><img src="@@PLUGINFILE@@/xeo4%20%281%29.gif" alt="" width="30" height="30" /></p> <pre> When doing it with careful handling I succeeded to a valid and correct display. So I must add some additional validate steps of the answer content. Hide Pierre Pichet added a comment - A valid one showing image in the answer and its feedback Show Pierre Pichet added a comment - A valid one showing image in the answer and its feedback Hide Tim Hunt added a comment - Right. That is a problem with the HTML editor. In the qtype_multichoice, I did CSS like https://github.com/moodle/moodle/blob/master/question/type/multichoice/styles.css#L5 to try to fix this, but I do not recommend it. It caused bugs like MDL-35343 and MDL-37845. We need a better solution. Show Tim Hunt added a comment - Right. That is a problem with the HTML editor. In the qtype_multichoice, I did CSS like https://github.com/moodle/moodle/blob/master/question/type/multichoice/styles.css#L5 to try to fix this, but I do not recommend it. It caused bugs like MDL-35343 and MDL-37845 . We need a better solution. Hide Pierre Pichet added a comment - The multichoice editor does not generate any <pre> html which could be a protection against hacking ? The edit_question_form.php set the editor options in the _construct to $this->editoroptions = array('subdirs' => 1, 'maxfiles' => EDITOR_UNLIMITED_FILES, 'context' =>$this->context, 'collapsed' => 1); In the edit_multichoice_form.php there is no cosntruct and on answerfield $repeated[] =$mform->createElement('editor', 'answer', $label, array('rows' => 1),$this->editoroptions); _cosntruct there is no reference to modifying the editoroptions However the 2 questiontexts do not behave the same way ... Show Pierre Pichet added a comment - The multichoice editor does not generate any <pre> html which could be a protection against hacking ? The edit_question_form.php set the editor options in the _construct to $this->editoroptions = array('subdirs' => 1, 'maxfiles' => EDITOR_UNLIMITED_FILES, 'context' =>$this->context, 'collapsed' => 1); In the edit_multichoice_form.php there is no cosntruct and on answerfield $repeated[] =$mform->createElement('editor', 'answer', $label, array('rows' => 1),$this->editoroptions); in qtype_multianswer_edit_form extends question_edit_form { _cosntruct there is no reference to modifying the editoroptions However the 2 questiontexts do not behave the same way ... Hide Pierre Pichet added a comment - - edited GOOD NEWS "Cannot reproduce" effect. When I edit a question from fresh text everything was OK. I did the prevous using a cut and paste from the Cloze docs so the copy contained the <pre>. As far as I remember, I tried to remove the <pre> but perhaps I was to tired. Anyway, perhaps we should test that there is no unbalanced <pre> </pre> in the question text of all question types as this could led to bad format in preview or quiz. In the Cloze this is more critical as the <pre> could be in the answer and the </pre> in the feedback ... I think we could add a rule in the docs to not put any HTML like <pre> inside the { } defining a question. The file handler or the editor seems to put automatically the image inside a <p> </p>. When polishing the code we should choose how to handle this so that the display is OK as default i.e. without <p> </p>. Show Pierre Pichet added a comment - - edited GOOD NEWS "Cannot reproduce" effect. When I edit a question from fresh text everything was OK. I did the prevous using a cut and paste from the Cloze docs so the copy contained the <pre>. As far as I remember, I tried to remove the <pre> but perhaps I was to tired. Anyway, perhaps we should test that there is no unbalanced <pre> </pre> in the question text of all question types as this could led to bad format in preview or quiz. In the Cloze this is more critical as the <pre> could be in the answer and the </pre> in the feedback ... I think we could add a rule in the docs to not put any HTML like <pre> inside the { } defining a question. The file handler or the editor seems to put automatically the image inside a <p> </p>. When polishing the code we should choose how to handle this so that the display is OK as default i.e. without <p> </p>. Hide Tim Hunt added a comment - Right. So the question is, how much validation should we try to do, and should we work on it using this issue, or create a new issue? Show Tim Hunt added a comment - Right. So the question is, how much validation should we try to do, and should we work on it using this issue, or create a new issue? Hide Pierre Pichet added a comment - I think that this validation can be included in this issue as there is already a quite complete validation in the actual code. I will look at the editor, there could be a possibility to control the data received from the file handler so that the <p> </p> is not generated automatically when inserting a file. I should have settle more things by next monday. Show Pierre Pichet added a comment - I think that this validation can be included in this issue as there is already a quite complete validation in the actual code. I will look at the editor, there could be a possibility to control the data received from the file handler so that the <p> </p> is not generated automatically when inserting a file. I should have settle more things by next monday. Hide Pierre Pichet added a comment - Tim, Jean-Pierre, Just to note some difficulties on working on the file handling. I can edit, import and export with files in questiontexts, answers (when allowed i.e. multichoice_v and multichoice_h) and answers feedback. Everything seems OK until I look at the database files table. If for an answer feedback even empty the itemid is set to the questiontext[itemid] then the database files will contain additional records for each of the images that are related to the questiontext[itemid]. So I need to check that that the fields contain effectively an image before setting the [itemid] to something else than empty. I am working on this as the images are not described in the same way when coming from edit_multianswer_form.php than from import format. Is there a way to limit the database files links to the files actually contained in a given element (i.e. answerfeedback[nn]) ? Show Pierre Pichet added a comment - Tim, Jean-Pierre, Just to note some difficulties on working on the file handling. I can edit, import and export with files in questiontexts, answers (when allowed i.e. multichoice_v and multichoice_h) and answers feedback. Everything seems OK until I look at the database files table. If for an answer feedback even empty the itemid is set to the questiontext [itemid] then the database files will contain additional records for each of the images that are related to the questiontext [itemid] . So I need to check that that the fields contain effectively an image before setting the [itemid] to something else than empty. I am working on this as the images are not described in the same way when coming from edit_multianswer_form.php than from import format. Is there a way to limit the database files links to the files actually contained in a given element (i.e. answerfeedback [nn] ) ? Hide Tim Hunt added a comment - It is not possible to link the the files acutally used by a given element. To understand why it is impossible, imagine that part of the input embeds a flash applet that loads the name of an image file from an XML file, all using relative URLs. I think the only option is to duplicate all the files into all the file areas. Because of the way the file pool works, only one copy of each file will be stored on disc. Show Tim Hunt added a comment - It is not possible to link the the files acutally used by a given element. To understand why it is impossible, imagine that part of the input embeds a flash applet that loads the name of an image file from an XML file, all using relative URLs. I think the only option is to duplicate all the files into all the file areas. Because of the way the file pool works, only one copy of each file will be stored on disc. Hide Pierre Pichet added a comment - I understand the principle. However there seems to be no mechanism inside the file handling to control if there is really a reference to a file in the element where the [itemid] is set to a value. To experiment I use the containing many subquestions. I just put 1 image in the main question and nowhere else I save the question and there were 60 new records in the mdl_files related to this image.. I then use the code with the additional control on using questiontext[itemid] When saving the question as new, only 2 records were added to the mdl_files and this reflects the reality. What should we do ? P.S. The filtering should be different i.e. @@PLUGINFILE@@ for format.php Show Pierre Pichet added a comment - I understand the principle. However there seems to be no mechanism inside the file handling to control if there is really a reference to a file in the element where the [itemid] is set to a value. To experiment I use the http://docs.moodle.org/24/en/Embedded_Answers_(Cloze)_question_type#Example_2 containing many subquestions. I just put 1 image in the main question and nowhere else I save the question and there were 60 new records in the mdl_files related to this image.. I then use the code with the additional control on using questiontext [itemid] https://github.com/ppichet/moodle/blob/a38fa7cb7baca7ff148e060544b4b196942b9b4e/question/type/multianswer/questiontype.php#L175 When saving the question as new, only 2 records were added to the mdl_files and this reflects the reality. What should we do ? P.S. The filtering should be different i.e. @@PLUGINFILE@@ for format.php Hide Jean-Michel Vedrine added a comment - Hello Pierre, I don't see the problem to create 60 records in mdl_files table as there is only 1 file for all of them in the filedir structure. The place wasted is minimal. Show Jean-Michel Vedrine added a comment - Hello Pierre, I don't see the problem to create 60 records in mdl_files table as there is only 1 file for all of them in the filedir structure. The place wasted is minimal. Hide Tim Hunt added a comment - Pierre, there is no way to sort out which files are used in which place. You could have a Cloze question like: And where popup1.html and popup2.html both refer (using a relative URL) to another file called styles.css or germanymap.png. There is no way for Moodle to unscramble that. You just have to duplicate the rows in the files table. Show Tim Hunt added a comment - Pierre, there is no way to sort out which files are used in which place. You could have a Cloze question like: {1:SHORTANSWER:=Berlin#<a target="_blank" href="@PLUGINFILE@/popup1.html">Click here</a>} is the capital of Germany <a target="_blank" href="@PLUGINFILE@/popup2.html">Click here</a>. And where popup1.html and popup2.html both refer (using a relative URL) to another file called styles.css or germanymap.png. There is no way for Moodle to unscramble that. You just have to duplicate the rows in the files table. Hide Pierre Pichet added a comment - Perhaps I am just an old-timer but I am not at ease that a table does not reflect the reality. This becomes a table that just tell you that perhaps a given element even an empty one (I just test it), could reference to a given file. However I don't know exactly how the cleaning of this table is done http://docs.moodle.org/dev/File_API_internals does not give clear indications of the exact process as when using the texteditor to change to a new file in a given question field there is no deleting. Show Pierre Pichet added a comment - Perhaps I am just an old-timer but I am not at ease that a table does not reflect the reality. This becomes a table that just tell you that perhaps a given element even an empty one (I just test it), could reference to a given file. However I don't know exactly how the cleaning of this table is done http://docs.moodle.org/dev/File_API_internals does not give clear indications of the exact process as when using the texteditor to change to a new file in a given question field there is no deleting. Hide Pierre Pichet added a comment - Tim, My objective is just to NOT set the param[itemid] 1. if the param[text] is empty 2. does not contain the @PLUGINFILE@ that is, I think, a clear signal that there is a link to a file when coming from some process as retrieving data from the database or from import format. 3. When retrieving from the edit_multianswer_form "/(draftfile.php)/" is part of the file info that can be used to identify that there is valid file. So which of these tests should I put in my proposal ? Show Pierre Pichet added a comment - Tim, My objective is just to NOT set the param [itemid] 1. if the param [text] is empty 2. does not contain the @PLUGINFILE@ that is, I think, a clear signal that there is a link to a file when coming from some process as retrieving data from the database or from import format. 3. When retrieving from the edit_multianswer_form "/(draftfile.php)/" is part of the file info that can be used to identify that there is valid file. So which of these tests should I put in my proposal ? Hide Jean-Michel Vedrine added a comment - I think you are trying to care for something that is not important at all because you will still have all files attached to a subquestion when it contains a single @PLUGINFILE@ or draftfile.php ! So it just complicate the code (and making it slower and more prone to break) without solving anything. When I say it's not important it is because that is just a bunch of lines in a table. When the question is deleted (or when an answer is deleted during question saving after editing) the filearea is cleaned and if it's the last reference to that binary file in the file pool the file is marked to be purged a few days later. On the contrary as you note "when using the texteditor to change to a new file in a given question field there is no deleting" and this is a very serious issue, but this is quite another story. There is already an issue in the tracker for that MDL-28019, and despite being one of the most voted tracker's issues, I seems no progress on it for years (this worry me because it's like a time bomb: big files like videos can accumulate in a filearea and suddenly backup/restore breaks without people being able to do anything). So IMHO, don't try to do any test about images in subquestions fields and just set itemid unconditionally. Show Jean-Michel Vedrine added a comment - I think you are trying to care for something that is not important at all because you will still have all files attached to a subquestion when it contains a single @PLUGINFILE@ or draftfile.php ! So it just complicate the code (and making it slower and more prone to break) without solving anything. When I say it's not important it is because that is just a bunch of lines in a table. When the question is deleted (or when an answer is deleted during question saving after editing) the filearea is cleaned and if it's the last reference to that binary file in the file pool the file is marked to be purged a few days later. On the contrary as you note "when using the texteditor to change to a new file in a given question field there is no deleting" and this is a very serious issue, but this is quite another story. There is already an issue in the tracker for that MDL-28019 , and despite being one of the most voted tracker's issues, I seems no progress on it for years (this worry me because it's like a time bomb: big files like videos can accumulate in a filearea and suddenly backup/restore breaks without people being able to do anything). So IMHO, don't try to do any test about images in subquestions fields and just set itemid unconditionally. Hide Pierre Pichet added a comment - Thanks Jean-Michel for your comment and the MDL-28019 reference. I think that I should at least test #1 for empty which in any case this could not "complicate the code (and making it slower and more prone to break) ". This test is done in the qtype_multianswer_extract_question() function. Show Pierre Pichet added a comment - Thanks Jean-Michel for your comment and the MDL-28019 reference. I think that I should at least test #1 for empty which in any case this could not "complicate the code (and making it slower and more prone to break) ". This test is done in the qtype_multianswer_extract_question() function. Hide Tim Hunt added a comment - Ah, testing for bits of text with no @pluginfile@ is a good idea! Pierre is right to be uneasy about this. It is not great, but we are constrained by: 1. Editing everything in a single HTML editor - that suggests we should only have one file area. 2. Wanting to re-use the existing code for rendering and serving files. That requires separate file areas. We are looking for the best compromise between the two, which I think we are close to. Show Tim Hunt added a comment - Ah, testing for bits of text with no @pluginfile@ is a good idea! Pierre is right to be uneasy about this. It is not great, but we are constrained by: 1. Editing everything in a single HTML editor - that suggests we should only have one file area. 2. Wanting to re-use the existing code for rendering and serving files. That requires separate file areas. We are looking for the best compromise between the two, which I think we are close to. Hide Pierre Pichet added a comment - - edited I just push on github my last version on which I was working this week. I can create, export moodle xml, backup, restore, move from category to another. To do the testing I propose to create some questions that illustrate various aspects and export them as moodle xml. I will create a quiz with those question and do a backup of the quiz and one for a simple course. This should be done by monday. We are near the 2,5 release which can overload the testers, this is a new feature and there are some real bugs to solve. Should I put this aside and come back to MDL-31680 ? Show Pierre Pichet added a comment - - edited I just push on github my last version on which I was working this week. I can create, export moodle xml, backup, restore, move from category to another. To do the testing I propose to create some questions that illustrate various aspects and export them as moodle xml. I will create a quiz with those question and do a backup of the quiz and one for a simple course. This should be done by monday. We are near the 2,5 release which can overload the testers, this is a new feature and there are some real bugs to solve. Should I put this aside and come back to MDL-31680 ? Hide Pierre Pichet added a comment - I just push a new version with a specific function to set the itemid that is also used in xml format import. Show Pierre Pichet added a comment - I just push a new version with a specific function to set the itemid that is also used in xml format import. Hide Pierre Pichet added a comment - a simple example Show Pierre Pichet added a comment - a simple example Hide Pierre Pichet added a comment - I just learn that you are " on holiday today and tomorrow ". This will give me time to set a proposal for the testing procedure . Show Pierre Pichet added a comment - I just learn that you are " on holiday today and tomorrow ". This will give me time to set a proposal for the testing procedure . Hide Pierre Pichet added a comment - From the discusion around MDL-39490, I understand that "Can we add this to master just after 2.5 branch is cut?" is yes Show Pierre Pichet added a comment - From the discusion around MDL-39490 , I understand that "Can we add this to master just after 2.5 branch is cut?" is yes Hide Pierre Pichet added a comment - - edited Testing was doing well until I test the validation in edit_multianswer_form. I add some supplmentary tests as we allowed image so HTML in multiple choice answers although the drop down menu (select element) does not allow HTML. The case of a single < could be interpreted in various ways because of the different places where the HTML possible elements are checked including the editor itself. I compared what happens in regular multichoice and in multichoice created in multianswer. In simple cases the HTML editor is doing a good job. For a regular multiplechoice answer we could find in the database if x < 4ac In other cases when editing a multichoice in edit_multianswer_form the conversion was not done, so the database contains if x2 < 0 What could be the best function to use to neutralize the single < in all cases? However some results are not the same that I had before rebase. I need to check again the validation of the select element multichoice. Anyway, have you more general comments on the code proposal i.e. the new function created to handle the itemid ? Show Pierre Pichet added a comment - - edited Testing was doing well until I test the validation in edit_multianswer_form. I add some supplmentary tests as we allowed image so HTML in multiple choice answers although the drop down menu (select element) does not allow HTML. The case of a single < could be interpreted in various ways because of the different places where the HTML possible elements are checked including the editor itself. I compared what happens in regular multichoice and in multichoice created in multianswer. In simple cases the HTML editor is doing a good job. For a regular multiplechoice answer we could find in the database <p>if x <sup>2 </sup>< 4ac <img src="@@PLUGINFILE@@/so42m.gif" alt="so4" width="40" height="40" /> </p> In other cases when editing a multichoice in edit_multianswer_form the conversion was not done, so the database contains if x<sup>2</sup> < 0 What could be the best function to use to neutralize the single < in all cases? However some results are not the same that I had before rebase. I need to check again the validation of the select element multichoice. Anyway, have you more general comments on the code proposal i.e. the new function created to handle the itemid ? Hide Pierre Pichet added a comment - I will drop the lines related to testing if multiplechoice answers could have an empty display in the select element. Looking through the renderer code, the choices foreach ($subq->get_order($qa) as $value =>$ansid) { $ans =$subq->answers[$ansid]; $choices[$value] =$subq->format_text($ans->answer,$ans->answerformat, $qa, 'question', 'answer',$ansid); if ($subq->is_choice_selected($response, $value)) { $matchinganswer = $ans; } } the choices contain all the info to display correctly the HTML (i.e. images). all the HTML rendering is done by$select = html_writer::select($choices,$qa->get_qt_field_name($fieldname),$response, array('' => ''), $inputattributes); which I cannot simulate in the edit_multianswer_form unless I add the resulting select in the form. Even if the select elements appear empty, there is no system error. However we could had a warning in edit_multianswer_form that the user should verify the select element rendering by doing a question preview. Show Pierre Pichet added a comment - I will drop the lines related to testing if multiplechoice answers could have an empty display in the select element. Looking through the renderer code, the choices foreach ($subq->get_order($qa) as$value => $ansid) {$ans = $subq->answers[$ansid]; $choices[$value] = $subq->format_text($ans->answer, $ans->answerformat,$qa, 'question', 'answer', $ansid); if ($subq->is_choice_selected($response,$value)) { $matchinganswer =$ans; } } the choices contain all the info to display correctly the HTML (i.e. images). all the HTML rendering is done by $select = html_writer::select($choices, $qa->get_qt_field_name($fieldname), $response, array('' => ''),$inputattributes); which I cannot simulate in the edit_multianswer_form unless I add the resulting select in the form. Even if the select elements appear empty, there is no system error. However we could had a warning in edit_multianswer_form that the user should verify the select element rendering by doing a question preview. Hide Tim Hunt added a comment - You ask "have you more general comments on the code proposal?, but is there some code I am supposed to be reviewing? Sorry, I am not sure what your question is. Show Tim Hunt added a comment - You ask "have you more general comments on the code proposal?, but is there some code I am supposed to be reviewing? Sorry, I am not sure what your question is. Hide Pierre Pichet added a comment - Sorry, I forgot to put the reference. Do you agree how I handle setting the itemid if there are files in the given element? Apart building various questions to import to test the various feature, is there unittests that you suggest to build ? Show Pierre Pichet added a comment - Sorry, I forgot to put the reference. Do you agree how I handle setting the itemid if there are files in the given element? Apart building various questions to import to test the various feature, is there unittests that you suggest to build ? Hide Tim Hunt added a comment - This is looking very promising. As far as I can see, this is basically right, and there are just details that need to be sorted out. I think the way you have only set itemid if there are files in the given element is good. 1. I don't think you should be calling $this->_form->setElementError in set_data. Surely this should be in the form validation method. (Or perhaps I don't understand this code yet?) 2. In lib.php, you are missing one argument , array$options=array() from the qtype_multianswer_pluginfile function. 3. With a function like set_subquestions_elements_itemid, I think it is better to use guard clauses (http://c2.com/cgi/wiki?GuardClause) rather than nesting the whole function inside a complicated if statement. 4. You have code like if (preg_match('/'.$searchcriteria.'/',$wrapped->questiontext['text'])) { $wrapped->questiontext['itemid']=$questiontextitemid; } else { $wrapped->questiontext['itemid']=''; } Is there a nice way to remove that duplication? (Basically, another method.) 5. I think trim($question->tolerance[$key]) == '' should use ===, otherwise we will get problems with 0. (https://github.com/ppichet/moodle/compare/MDL-26511#L7R209) 6. You have some code styles issues that code checker will tell you about when you run it. I don't think it is easy to create unit tests for this. I think just write good manual testing instructions here. Show Tim Hunt added a comment - This is looking very promising. As far as I can see, this is basically right, and there are just details that need to be sorted out. I think the way you have only set itemid if there are files in the given element is good. 1. I don't think you should be calling$this->_form->setElementError in set_data. Surely this should be in the form validation method. (Or perhaps I don't understand this code yet?) 2. In lib.php, you are missing one argument , array $options=array() from the qtype_multianswer_pluginfile function. 3. With a function like set_subquestions_elements_itemid, I think it is better to use guard clauses ( http://c2.com/cgi/wiki?GuardClause ) rather than nesting the whole function inside a complicated if statement. 4. You have code like if (preg_match('/'.$searchcriteria.'/', $wrapped->questiontext['text'])) {$wrapped->questiontext['itemid']=$questiontextitemid; } else {$wrapped->questiontext['itemid']=''; } Is there a nice way to remove that duplication? (Basically, another method.) 5. I think trim($question->tolerance [$key] ) == '' should use ===, otherwise we will get problems with 0. ( https://github.com/ppichet/moodle/compare/MDL-26511#L7R209 ) 6. You have some code styles issues that code checker will tell you about when you run it. I don't think it is easy to create unit tests for this. I think just write good manual testing instructions here. Hide Tim Hunt added a comment - As usual, I forgot to click the buttons. Show Tim Hunt added a comment - As usual, I forgot to click the buttons. Hide Pierre Pichet added a comment - 1.We are not in the validation process but in setting the default values usually when doing a submit on "decode and verify the question text" . So this is the way used in the quite non standard edit_multianwer_form . 2. Options Thanks, I copy from a to old file... 3. I thought that the complex if will be sufficient to exclude bad cases. i.e. there are subquestions, the questiontext-itemid exists and is not null if ($question->options->questions != '' && isset($question->questiontext['itemid']) && $question->questiontext['itemid'] != '' &&$searchcriteria != '') if it does not satify the criteria, the question is returned without any modifications. I could add a isset ($question->options->questions) 4. The objective is to minimize the use of itemid if there is no image in the subquestions questiontext. Each time I set the itemid to an element there is a creation of links to this element and all the files included in the total question. Or I don't understand your point. Notice that this is used by two process (editing a question or import) . In the preceeding process that create this structure, the itemid could have been set to questiontext id automatically. 5. This is a special case that I encounter when testing. The qtype_multianswer_extract_question() does not handle well * in numerical format (which is a rare case...) so the tolerance was not set. I do think that == '' will distinguih from == 0 which is not the case of the empty() function. But if you think === is better. 6. I think that there is even a print_r left I will remove the validation of the multiplechoice in-line to detect empty rendering of HTML code. However today I added a select element that will display the choices as they will appear in "real life". The user will be able to check before previewing the question. This will be available on the next github update. Show Pierre Pichet added a comment - Thanks for the comments. 1.We are not in the validation process but in setting the default values usually when doing a submit on "decode and verify the question text" . So this is the way used in the quite non standard edit_multianwer_form . 2. Options Thanks, I copy from a to old file... 3. I thought that the complex if will be sufficient to exclude bad cases. i.e. there are subquestions, the questiontext-itemid exists and is not null if ($question->options->questions != '' && isset($question->questiontext['itemid']) &&$question->questiontext['itemid'] != '' && $searchcriteria != '') if it does not satify the criteria, the question is returned without any modifications. I could add a isset ($question->options->questions) 4. The objective is to minimize the use of itemid if there is no image in the subquestions questiontext. Each time I set the itemid to an element there is a creation of links to this element and all the files included in the total question. Or I don't understand your point. Notice that this is used by two process (editing a question or import) . In the preceeding process that create this structure, the itemid could have been set to questiontext id automatically. 5. This is a special case that I encounter when testing. The qtype_multianswer_extract_question() does not handle well * in numerical format (which is a rare case...) so the tolerance was not set. I do think that == '' will distinguih from == 0 which is not the case of the empty() function. But if you think === is better. 6. I think that there is even a print_r left I will remove the validation of the multiplechoice in-line to detect empty rendering of HTML code. However today I added a select element that will display the choices as they will appear in "real life". The user will be able to check before previewing the question. This will be available on the next github update. Hide Pierre Pichet added a comment - - edited About the complex if sequence, this is a special case were the return is always the $question object. I could wrote them differently to clarify the code. I should perhaps add isset tests ( answer) in the code flow for incomplete questions structure. However the preceeding function define default elements like answer feedback. I will loook for minimal additional tests. Show Pierre Pichet added a comment - - edited About item 3 About the complex if sequence, this is a special case were the return is always the$question object. I could wrote them differently to clarify the code. I should perhaps add isset tests ( answer) in the code flow for incomplete questions structure. However the preceeding function define default elements like answer feedback. I will loook for minimal additional tests. Hide Pierre Pichet added a comment - Illustration of the menu select when Decode and verify a regular multichoice. note the image in the feedback of one answer. Show Pierre Pichet added a comment - Illustration of the menu select when Decode and verify a regular multichoice. note the image in the feedback of one answer. Hide Pierre Pichet added a comment - An example of images in answers or feedback Show Pierre Pichet added a comment - An example of images in answers or feedback Hide Pierre Pichet added a comment - The master version has been rebase to actual master. I am waiting for this week version before rebasing if you think that this is ready for testing. Show Pierre Pichet added a comment - The master version has been rebase to actual master. I am waiting for this week version before rebasing if you think that this is ready for testing. Hide Pierre Pichet added a comment - Tim, Closing for holidays June 15 - Aug 15 as I will not have access to nothing more than an Ipad in this period. This weekend I will rebase to this week moodle versions. To which version(s) should I rebase if you think that this is ready for testing and integrate. If something goes wrong, I could possibly correct it in the next week. Show Pierre Pichet added a comment - Tim, Closing for holidays June 15 - Aug 15 as I will not have access to nothing more than an Ipad in this period. This weekend I will rebase to this week moodle versions. To which version(s) should I rebase if you think that this is ready for testing and integrate. If something goes wrong, I could possibly correct it in the next week. Hide Pierre Pichet added a comment - In case you did not notice... Show Pierre Pichet added a comment - In case you did not notice... Hide Tim Hunt added a comment - Sorry for the delay. I have now reviewed this, and I think the change is good, although it is a big complex change, and I am not yet 100% sure. What still needs to be done? 1. We need testing instructions. 2. It would be really nice to have unit tests for some of the complex bits of logic in the new code, but I guess that is not easy, so we can live without them. 3. There are some minor coding style things, which are probably things that code-checker does not catch. The main one is that I would put a space either side of =. Again, I could live with the patch the way it is. Show Tim Hunt added a comment - Sorry for the delay. I have now reviewed this, and I think the change is good, although it is a big complex change, and I am not yet 100% sure. What still needs to be done? 1. We need testing instructions. 2. It would be really nice to have unit tests for some of the complex bits of logic in the new code, but I guess that is not easy, so we can live without them. 3. There are some minor coding style things, which are probably things that code-checker does not catch. The main one is that I would put a space either side of =. Again, I could live with the patch the way it is. Hide Pierre Pichet added a comment - I will put the testing instructions tonight. Mainly import the some questions from a given file (I will specify) among them there is one which put specific images in the question text, answers for multi and feedback for all question types and the same questions without images set_subquestions_elements_itemid($question, '@@PLUGINFILE@@'); and looking at the file database records that the setting of image links are only created if there is an image in the given element. This also verify that the import is OK. Then edit copy the questions , test the decode verify display, save the question. This will test the filtering process set_subquestions_elements_itemid($question, 'draftfile.php'); Create a copy of the question to another category. Move the questions to another category and context. Create a quiz, test OK. Do backup and restore process either to the same course or another course of a quiz ( the questions will be included) I will verify the code more closely Hopefully everything should be ready for tomorrow. Show Pierre Pichet added a comment - I will put the testing instructions tonight. Mainly import the some questions from a given file (I will specify) among them there is one which put specific images in the question text, answers for multi and feedback for all question types and the same questions without images set_subquestions_elements_itemid($question, '@@PLUGINFILE@@'); and looking at the file database records that the setting of image links are only created if there is an image in the given element. This also verify that the import is OK. Then edit copy the questions , test the decode verify display, save the question. This will test the filtering process set_subquestions_elements_itemid($question, 'draftfile.php'); Create a copy of the question to another category. Move the questions to another category and context. Create a quiz, test OK. Do backup and restore process either to the same course or another course of a quiz ( the questions will be included) I will verify the code more closely Hopefully everything should be ready for tomorrow. Hide Pierre Pichet added a comment - preview of a question with images in answers and feedback Show Pierre Pichet added a comment - preview of a question with images in answers and feedback Hide Pierre Pichet added a comment - Rebase master, correct =, add examples and instructions. Show Pierre Pichet added a comment - Rebase master, correct =, add examples and instructions. Hide Tim Hunt added a comment - Thanks Pierre. Submitting for integration review now. Show Tim Hunt added a comment - Thanks Pierre. Submitting for integration review now. Hide Dan Poltawski added a comment - Integrated to master, thanks Pierre. I edited your commit to ensure you added yourself as copyright holder of the file you created rather than dongsheng Show Dan Poltawski added a comment - Integrated to master, thanks Pierre. I edited your commit to ensure you added yourself as copyright holder of the file you created rather than dongsheng Hide Dan Poltawski added a comment - Hi Pierre, This looks to be breaking unit tests There was 1 error: Undefined index: itemid /Users/danp/git/integration/question/format/xml/format.php:456 /Users/danp/git/integration/question/format/xml/tests/xmlformat_test.php:1308 To re-run: vendor/bin/phpunit qformat_xml_test question/format/xml/tests/xmlformat_test.php FAILURES! Tests: 1845, Assertions: 32077, Errors: 1, Skipped: 5. Show Dan Poltawski added a comment - Hi Pierre, This looks to be breaking unit tests There was 1 error: 1) qformat_xml_test::test_import_multianswer Undefined index: itemid /Users/danp/git/integration/question/type/multianswer/questiontype.php:362 /Users/danp/git/integration/question/format/xml/format.php:456 /Users/danp/git/integration/question/format/xml/tests/xmlformat_test.php:1308 /Users/danp/git/integration/lib/phpunit/classes/advanced_testcase.php:76 To re-run: vendor/bin/phpunit qformat_xml_test question/format/xml/tests/xmlformat_test.php FAILURES! Tests: 1845, Assertions: 32077, Errors: 1, Skipped: 5. Hide Jean-Michel Vedrine added a comment - - edited Hello Dan and Pierre, There is a problem in the code when question text doesn't contain any embedded image, because in qformat_xml in the import_multianswer function lines 454-455 $questiontext =$this->import_text_with_files($question, array('#', 'questiontext', 0)); will only create a$questiontext array with 'text' and 'format' elements but no 'itemid' element (this is how it works, and should not be changed because we will need to change other places too that rely on not having itemid when there is no draftfile) So in multianswer questiontype you should check for that case in the qtype_multianswer_extract_question function and also the comment // Variable $text is an array [text][format][itemid]. // If the main question contains a file then its [itemid] // will not be empty. // The other subquestions question , answers feedback and // multiple choice vertical and horizontal answers should be declared // array and should have [itemid] set to [text][itemid]. is wrong because this is not how it works: the array is only [text][format] when there is no draftfile so rather than saying "will not be empty" it should be "will not be set". Sorry for not having spotted this problem when I looked at the code (and I should have run the phpunit tests too !!) Pierre if you want to further discuss on the best way to solve this, I am available all the day because course and exam are over for this year Show Jean-Michel Vedrine added a comment - - edited Hello Dan and Pierre, There is a problem in the code when question text doesn't contain any embedded image, because in qformat_xml in the import_multianswer function lines 454-455$questiontext = $this->import_text_with_files($question, array('#', 'questiontext', 0)); will only create a $questiontext array with 'text' and 'format' elements but no 'itemid' element (this is how it works, and should not be changed because we will need to change other places too that rely on not having itemid when there is no draftfile) So in multianswer questiontype you should check for that case in the qtype_multianswer_extract_question function and also the comment // Variable$text is an array [text][format][itemid]. // If the main question contains a file then its [itemid] // will not be empty. // The other subquestions question , answers feedback and // multiple choice vertical and horizontal answers should be declared // array and should have [itemid] set to [text][itemid]. is wrong because this is not how it works: the array is only [text] [format] when there is no draftfile so rather than saying "will not be empty" it should be "will not be set". Sorry for not having spotted this problem when I looked at the code (and I should have run the phpunit tests too !!) Pierre if you want to further discuss on the best way to solve this, I am available all the day because course and exam are over for this year Hide Jean-Michel Vedrine added a comment - I think that simply testing if (isset($question->questiontext['itemid'])) should correct the problem Show Jean-Michel Vedrine added a comment - I think that simply testing if (isset($question->questiontext ['itemid'] )) should correct the problem Hide Dan Poltawski added a comment - Thanks Jean-Michel for investigating. Piere, if you could confirm it would great. Show Dan Poltawski added a comment - Thanks Jean-Michel for investigating. Piere, if you could confirm it would great. Hide Jean-Michel Vedrine added a comment - Well re-thinking to it now I am not sure this was a good decision from me when implementing using draftfiles in question import. Maybe it would have been best to have a constant structure and create an itemid in all cases in import_files_as_draft function ? After all there is an itemid form each editor in the question creation/edition form even if it doesn't contains any fie ! But unfortunately I think we have to live with that now. Show Jean-Michel Vedrine added a comment - Well re-thinking to it now I am not sure this was a good decision from me when implementing using draftfiles in question import. Maybe it would have been best to have a constant structure and create an itemid in all cases in import_files_as_draft function ? After all there is an itemid form each editor in the question creation/edition form even if it doesn't contains any fie ! But unfortunately I think we have to live with that now. Hide Pierre Pichet added a comment - - edited As a first comment before breakfast, I think that the import process should create the $question->questiontext['itemid'] even an empty one as long as its creates the structure [text][format]. why "But unfortunately I think we have to live with that now." ? I let others ( Dan , Tim) decide where the test should be put. Sorry, I did run the tests more than once in the coding process but as evidence not in the last version. Show Pierre Pichet added a comment - - edited As a first comment before breakfast, I think that the import process should create the$question->questiontext ['itemid'] even an empty one as long as its creates the structure [text] [format] . why "But unfortunately I think we have to live with that now." ? I let others ( Dan , Tim) decide where the test should be put. Sorry, I did run the tests more than once in the coding process but as evidence not in the last version. Hide Jean-Michel Vedrine added a comment - - edited Unfortunately I don't think changing import_files_as_draft is so easy because of the implications in question/format.php and in all the tests that would have to be modified. Also we would have to do a lot of tests to be sure this don't create any regression elsewhere. So in my opinion there is a choice between 2 very different options ### Quick fix My current thinking is that adding some tests if (isset($question->questiontext['itemid'])) before using it would be enough to fix the problem but you know this code better than me so you should say if you agree or not with this way of fixing the problem. This can be done and tested in a reasonable time so should be doable this week. ### Complicated fix Modify all the code so that itemid is created in all cases. I think that this need other changes elsewhere but I will make some tests to verify that this is true. Modifiying such a central function used to import all text fields during xml import is IMHO not doable during integration (and without Tim approval ! Don't forget he is on holidays) So if we choose this way, I think we need to revert this change for current integration and do more work until we are certain all is working (including in the lesson module because lesson is also using this code in an awful way !) and that there is no regression. Show Jean-Michel Vedrine added a comment - - edited Unfortunately I don't think changing import_files_as_draft is so easy because of the implications in question/format.php and in all the tests that would have to be modified. Also we would have to do a lot of tests to be sure this don't create any regression elsewhere. So in my opinion there is a choice between 2 very different options Quick fix Only modify qtype_multianswer_extract_question in question/type/multianswer/questiontype.php My current thinking is that adding some tests if (isset($question->questiontext['itemid'])) before using it would be enough to fix the problem but you know this code better than me so you should say if you agree or not with this way of fixing the problem. This can be done and tested in a reasonable time so should be doable this week. Complicated fix Modify all the code so that itemid is created in all cases. I think that this need other changes elsewhere but I will make some tests to verify that this is true. Modifiying such a central function used to import all text fields during xml import is IMHO not doable during integration (and without Tim approval ! Don't forget he is on holidays) So if we choose this way, I think we need to revert this change for current integration and do more work until we are certain all is working (including in the lesson module because lesson is also using this code in an awful way !) and that there is no regression. Hide Pierre Pichet added a comment - The time scale is not important as we only put this on master. I will be on holidays without access to more than an Ipad from june 15 to august 15. So waiting appears the best. Show Pierre Pichet added a comment - The time scale is not important as we only put this on master. I will be on holidays without access to more than an Ipad from june 15 to august 15. So waiting appears the best. Hide Dan Poltawski added a comment - Hi Everyone, I'm not confident that we're clear on the best way forward here and we need to get the unit tets passing. In the absence of Tim, i've decided its best to revert it so we can consider the complete solution. Thanks Show Dan Poltawski added a comment - Hi Everyone, I'm not confident that we're clear on the best way forward here and we need to get the unit tets passing. In the absence of Tim, i've decided its best to revert it so we can consider the complete solution. Thanks Hide Moving this reopened issue out from current integration. Please, re-submit it for integration once ready. Show CiBoT added a comment - Moving this reopened issue out from current integration. Please, re-submit it for integration once ready. Hide Jean-Michel Vedrine added a comment - Thanks Dan, I think this is the right thing to do. Show Jean-Michel Vedrine added a comment - Thanks Dan, I think this is the right thing to do. Hide Pierre Pichet added a comment - I agree. Show Pierre Pichet added a comment - I agree. Hide Dan Poltawski added a comment - Great - thanks guys Show Dan Poltawski added a comment - Great - thanks guys Hide Pierre Pichet added a comment - Jean-Michel, Looking more closely to the code, the quick fix apppears the best way to solve the problem. So I put it , test that the unit test is Ok and push the result on github. If you think that this is Ok, you can finish the process. I just realize that I push it using the -f option so the lines added are included in main issue. Show Pierre Pichet added a comment - Jean-Michel, Looking more closely to the code, the quick fix apppears the best way to solve the problem. So I put it , test that the unit test is Ok and push the result on github. If you think that this is Ok, you can finish the process. I just realize that I push it using the -f option so the lines added are included in main issue. Hide Tim Hunt added a comment - Can you summarise what changes were made in the quick fix. That would make it easier to review. Thanks. Show Tim Hunt added a comment - Can you summarise what changes were made in the quick fix. That would make it easier to review. Thanks. Hide Tim Hunt added a comment - Oops! No, you can't You are on holiday. Show Tim Hunt added a comment - Oops! No, you can't You are on holiday. Hide Jean-Michel Vedrine added a comment - - edited Hello Tim and Pierre, Can you summarise where we are with this issue ? I must admit I am somewhat lost, because I don't know if there is any problem left or not. Show Jean-Michel Vedrine added a comment - - edited Hello Tim and Pierre, Can you summarise where we are with this issue ? I must admit I am somewhat lost, because I don't know if there is any problem left or not. Hide Pierre Pichet added a comment - Hi Jean-Michel, Good that you can come back to this as a kind of Happy New Year. By the way, I am beginning a 3 years 50% duty preretirement program which should let me more time for other things like home-improvment and moodle as long as my wife agrees... One thing that has changed is that the file handling under the moodle course files system is an obsolete process under 2,5+ see http://docs.moodle.org/25/en/Repositories "(Note that you cannot upload files into a repository from Moodle.)" I don't understand clearly how it is working but as the initial proposal of this issue is to put files in the obsolete moodle system, I think that this issue could be more or less obsolete. ??? Show Pierre Pichet added a comment - Hi Jean-Michel, Good that you can come back to this as a kind of Happy New Year. By the way, I am beginning a 3 years 50% duty preretirement program which should let me more time for other things like home-improvment and moodle as long as my wife agrees... One thing that has changed is that the file handling under the moodle course files system is an obsolete process under 2,5+ see http://docs.moodle.org/25/en/Repositories "(Note that you cannot upload files into a repository from Moodle.)" I don't understand clearly how it is working but as the initial proposal of this issue is to put files in the obsolete moodle system, I think that this issue could be more or less obsolete. ??? Hide Jean-Michel Vedrine added a comment - Hello Pierre, Happy new year 2014. I will be a happy retired teacher in June 2016 ! Unfortunately progressive pre-retirement program is no more possible here in France. I think you are confused because the actual state of the code for this issue in your github repo https://github.com/ppichet/moodle/compare/MDL-26511 is already using the new Moodle filesystem. IMHO the remaining questions are only • does it works in all cases ? • does it breaks any unit test ? • are the testing instructions complete enough to resubmit for integration ? Show Jean-Michel Vedrine added a comment - Hello Pierre, Happy new year 2014. I will be a happy retired teacher in June 2016 ! Unfortunately progressive pre-retirement program is no more possible here in France. I think you are confused because the actual state of the code for this issue in your github repo https://github.com/ppichet/moodle/compare/MDL-26511 is already using the new Moodle filesystem. IMHO the remaining questions are only does it works in all cases ? does it breaks any unit test ? are the testing instructions complete enough to resubmit for integration ? Hide Pierre Pichet added a comment - "already using the new Moodle filesystem" The code already use the new Moodle file system in the general option that the files are saved with the new hash coding in the moodledata directory. However I am not sure that doing this, I cover all the new possibilities • the now obsolete course file directory • the new personal file directory • any of the external allowed file storages like Google etc. I need to reexplore how other questiontypes like multichoice handle files starting first by http://docs.moodle.org/dev/File_API_internals Show Pierre Pichet added a comment - "already using the new Moodle filesystem" The code already use the new Moodle file system in the general option that the files are saved with the new hash coding in the moodledata directory. However I am not sure that doing this, I cover all the new possibilities the now obsolete course file directory the new personal file directory any of the external allowed file storages like Google etc. I need to reexplore how other questiontypes like multichoice handle files starting first by http://docs.moodle.org/dev/File_API_internals Hide Jean-Michel Vedrine added a comment - No, You don't need to look at repositories. And in fact you can't ! All files associated with an editor instance are draft files whatever repositories they came from originally. If you look at other question types you will not find any code related to repositories at all. Show Jean-Michel Vedrine added a comment - No, You don't need to look at repositories. And in fact you can't ! All files associated with an editor instance are draft files whatever repositories they came from originally. If you look at other question types you will not find any code related to repositories at all. Hide Pierre Pichet added a comment - OK, I just test on UQAM Moodle 2.5 that all files used in an activity are stored in the moodledata directory. So what remains is to clean the problems with the unit tests and generate the testing instructions once the code is updated to the last version. However I will received tomorrow a new computer which means some additional significant delays . Show Pierre Pichet added a comment - OK, I just test on UQAM Moodle 2.5 that all files used in an activity are stored in the moodledata directory. So what remains is to clean the problems with the unit tests and generate the testing instructions once the code is updated to the last version. However I will received tomorrow a new computer which means some additional significant delays . ## People • Assignee: Pierre Pichet Reporter: Pierre Pichet Peer reviewer: Tim Hunt Integrator: Dan Poltawski Participants:	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4598059356212616, "perplexity": 2450.129796438697}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-18/segments/1461860115836.8/warc/CC-MAIN-20160428161515-00101-ip-10-239-7-51.ec2.internal.warc.gz"}
https://sourceforge.net/p/texniccenter/bugs/340/	## #340 In outline pane remove tex formatting from section headings open nobody 5 2012-12-05 2012-11-22 Mario Valle No Writing for a journal I'm forced to use section headings like the following: \section{\sffamily \Large Seeing and Understanding} \subsubsection{\sffamily \normalsize Colors} Is it possible to remove the latex formatting commands before outputting the section title? I know this is not a general solution, things like \textbf{Interactivity} needs more work. This is a low priority enhancement request. I hope the journal latex knowledge will improve in the future... Thanks! mario ## Discussion • Tino Weinkauf - 2012-12-05 So sorry that you have to write for such a journal! ;-) Anyway, I will add this as a bug report. I am surprised that we did not do this yet. • Tino Weinkauf - 2012-12-05 The described error has been added to the official bug list.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9759001135826111, "perplexity": 3745.420527021825}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948551162.54/warc/CC-MAIN-20171214222204-20171215002204-00090.warc.gz"}
http://peeterjoot.com/tag/charge-distribution/	[Click here for a PDF of this post with nicer formatting] When computing the most general solution of the electrostatic potential in a plane, Jackson [1] mentions that $$-2 \lambda_0 \ln \rho$$ is the well known potential for an infinite line charge (up to the unit specific factor). Checking that statement, since I didn’t recall what that potential was offhand, I encountered some inconsistencies and non-convergent integrals, and thought it was worthwhile to explore those a bit more carefully. This will be done here. ### Using Gauss’s law. For an infinite length line charge, we can find the radial field contribution using Gauss’s law, imagining a cylinder of length $$\Delta l$$ of radius $$\rho$$ surrounding this charge with the midpoint at the origin. Ignoring any non-radial field contribution, we have \label{eqn:lineCharge:20} \int_{-\Delta l/2}^{\Delta l/2} \ncap \cdot \BE (2 \pi \rho) dl = \frac{\lambda_0}{\epsilon_0} \Delta l, or \label{eqn:lineCharge:40} \BE = \frac{\lambda_0}{2 \pi \epsilon_0} \frac{\rhocap}{\rho}. Since \label{eqn:lineCharge:60} \frac{\rhocap}{\rho} = \spacegrad \ln \rho, this means that the potential is \label{eqn:lineCharge:80} \phi = -\frac{2 \lambda_0}{4 \pi \epsilon_0} \ln \rho. ### Finite line charge potential. Let’s try both these calculations for a finite charge distribution. Gauss’s law looses its usefulness, but we can evaluate the integrals directly. For the electric field \label{eqn:lineCharge:100} \BE = \frac{\lambda_0}{4 \pi \epsilon_0} \int \frac{(\Bx – \Bx’)}{\Abs{\Bx – \Bx’}^3} dl’. Using cylindrical coordinates with the field point $$\Bx = \rho \rhocap$$ for convience, the charge point $$\Bx’ = z’ \zcap$$, and a the charge distributed over $$[a,b]$$ this is \label{eqn:lineCharge:120} \BE = \frac{\lambda_0}{4 \pi \epsilon_0} \int_a^b \frac{(\rho \rhocap – z’ \zcap)}{\lr{\rho^2 + (z’)^2}^{3/2}} dz’. When the charge is uniformly distributed around the origin $$[a,b] = b[-1,1]$$ the $$\zcap$$ component of this field is killed because the integrand is odd. This justifies ignoring such contributions in the Gaussing cylinder analysis above. The general solution to this integral is found to be \label{eqn:lineCharge:140} \BE = \frac{\lambda_0}{4 \pi \epsilon_0} \evalrange{ \lr{ \frac{z’ \rhocap }{\rho \sqrt{ \rho^2 + (z’)^2 } } +\frac{\zcap}{ \sqrt{ \rho^2 + (z’)^2 } } } }{a}{b}, or \label{eqn:lineCharge:240} \boxed{ \BE = \frac{\lambda_0}{4 \pi \epsilon_0} \lr{ \frac{\rhocap }{\rho} \lr{ \frac{b}{\sqrt{ \rho^2 + b^2 } } -\frac{a}{\sqrt{ \rho^2 + a^2 } } } + \zcap \lr{ \frac{1}{ \sqrt{ \rho^2 + b^2 } } -\frac{1}{ \sqrt{ \rho^2 + a^2 } } } }. } When $$b = -a = \Delta l/2$$, this reduces to \label{eqn:lineCharge:160} \BE = \frac{\lambda_0}{4 \pi \epsilon_0} \frac{\rhocap }{\rho} \frac{\Delta l}{\sqrt{ \rho^2 + (\Delta l/2)^2 } }, which further reduces to \ref{eqn:lineCharge:40} when $$\Delta l \gg \rho$$. ### Finite line charge potential. Wrong but illuminating. Again, putting the field point at $$z’ = 0$$, we have \label{eqn:lineCharge:180} \phi(\rho) = \frac{\lambda_0}{4 \pi \epsilon_0} \int_a^b \frac{dz’}{\lr{\rho^2 + (z’)^2}^{1/2}}, which integrates to \label{eqn:lineCharge:260} \phi(\rho) = \frac{\lambda_0}{4 \pi \epsilon_0 } \ln \frac{ b + \sqrt{ \rho^2 + b^2 }}{ a + \sqrt{\rho^2 + a^2}}. With $$b = -a = \Delta l/2$$, this approaches \label{eqn:lineCharge:200} \phi \approx \frac{\lambda_0}{4 \pi \epsilon_0 } \ln \frac{ (\Delta l/2) }{ \rho^2/2\Abs{\Delta l/2}} = \frac{-2 \lambda_0}{4 \pi \epsilon_0 } \ln \rho + \frac{\lambda_0}{4 \pi \epsilon_0 } \ln \lr{ (\Delta l)^2/2 }. Before $$\Delta l$$ is allowed to tend to infinity, this is identical (up to a difference in the reference potential) to \ref{eqn:lineCharge:80} found using Gauss’s law. It is, strictly speaking, singular when $$\Delta l \rightarrow \infty$$, so it does not seem right to infinity as a reference point for the potential. There’s another weird thing about this result. Since this has no $$z$$ dependence, it is not obvious how we would recover the non-radial portion of the electric field from this potential using $$\BE = -\spacegrad \phi$$? Let’s calculate the elecric field from \ref{eqn:lineCharge:180} explicitly \label{eqn:lineCharge:220} \begin{aligned} \BE &= -\frac{\lambda_0}{4 \pi \epsilon_0} \spacegrad \ln \frac{ b + \sqrt{ \rho^2 + b^2 }}{ a + \sqrt{\rho^2 + a^2}} \\ &= -\frac{\lambda_0 \rhocap}{4 \pi \epsilon_0 } \PD{\rho}{} \ln \frac{ b + \sqrt{ \rho^2 + b^2 }}{ a + \sqrt{\rho^2 + a^2}} \\ &= -\frac{\lambda_0 \rhocap}{4 \pi \epsilon_0} \lr{ \inv{ b + \sqrt{ \rho^2 + b^2 }} \frac{ \rho }{\sqrt{ \rho^2 + b^2 }} -\inv{ a + \sqrt{ \rho^2 + a^2 }} \frac{ \rho }{\sqrt{ \rho^2 + a^2 }} } \\ &= -\frac{\lambda_0 \rhocap}{4 \pi \epsilon_0 \rho} \lr{ \frac{ -b + \sqrt{ \rho^2 + b^2 }}{\sqrt{ \rho^2 + b^2 }} -\frac{ -a + \sqrt{ \rho^2 + a^2 }}{\sqrt{ \rho^2 + a^2 }} } \\ &= \frac{\lambda_0 \rhocap}{4 \pi \epsilon_0 \rho} \lr{ \frac{ b }{\sqrt{ \rho^2 + b^2 }} -\frac{ a }{\sqrt{ \rho^2 + a^2 }} }. \end{aligned} This recovers the radial component of the field from \ref{eqn:lineCharge:240}, but where did the $$\zcap$$ component go? The required potential appears to be \label{eqn:lineCharge:340} \phi(\rho, z) = \frac{\lambda_0}{4 \pi \epsilon_0 } \ln \frac{ b + \sqrt{ \rho^2 + b^2 }}{ a + \sqrt{\rho^2 + a^2}} \frac{z \lambda_0}{4 \pi \epsilon_0 } \lr{ \frac{1}{\sqrt{\rho^2 + b^2}} -\frac{1}{\sqrt{\rho^2 + a^2}} }. When computing the electric field $$\BE(\rho, \theta, z)$$, it was convienent to pick the coordinate system so that $$z = 0$$. Doing this with the potential gives the wrong answers. The reason for this appears to be that this kills the potential term that is linear in $$z$$ before taking its gradient, and we need that term to have the $$\zcap$$ field component that is expected for a charge distribution that is non-symmetric about the origin on the z-axis! ### Finite line charge potential. Take II. Let the point at which the potential is evaluated be \label{eqn:lineCharge:360} \Bx = \rho \rhocap + z \zcap, and the charge point be \label{eqn:lineCharge:380} \Bx’ = z’ \zcap. This gives \label{eqn:lineCharge:400} \begin{aligned} \phi(\rho, z) &= \frac{\lambda_0}{4\pi \epsilon_0} \int_a^b \frac{dz’}{\Abs{\rho^2 + (z – z’)^2 }} \\ &= \frac{\lambda_0}{4\pi \epsilon_0} \int_{a-z}^{b-z} \frac{du}{ \Abs{\rho^2 + u^2} } \\ &= \frac{\lambda_0}{4\pi \epsilon_0} \evalrange{\ln \lr{ u + \sqrt{ \rho^2 + u^2 }}}{b-z}{a-z} \\ &= \frac{\lambda_0}{4\pi \epsilon_0} \ln \frac { b-z + \sqrt{ \rho^2 + (b-z)^2 }} { a-z + \sqrt{ \rho^2 + (a-z)^2 }}. \end{aligned} The limit of this potential $$a = -\Delta/2 \rightarrow -\infty, b = \Delta/2 \rightarrow \infty$$ doesn’t exist in any strict sense. If we are cavilier about the limits, as in \ref{eqn:lineCharge:200}, this can be evaluated as \label{eqn:lineCharge:n} \phi \approx \frac{\lambda_0}{4\pi \epsilon_0} \lr{ -2 \ln \rho + \textrm{constant} }. however, the constant ($$\ln \Delta^2/2$$) is infinite, so there isn’t really a good justification for using that constant as the potential reference point directly. It seems that the “right” way to calculate the potential for the infinite distribution, is to • Calculate the field from the potential. • Take the PV limit of that field with the charge distribution extending to infinity. • Compute the corresponding potential from this limiting value of the field. Doing that doesn’t blow up. That field calculation, for the finite case, should include a $$\zcap$$ component. To verify, let’s take the respective derivatives \label{eqn:lineCharge:420} \begin{aligned} -\PD{z}{} \phi &= -\frac{\lambda_0}{4\pi \epsilon_0} \lr{ \frac{ -1 + \frac{z – b}{\sqrt{ \rho^2 + (b-z)^2 }} }{ b-z + \sqrt{ \rho^2 + (b-z)^2 } } \frac{ -1 + \frac{z – a}{\sqrt{ \rho^2 + (a-z)^2 }} }{ a-z + \sqrt{ \rho^2 + (a-z)^2 } } } \\ &= \frac{\lambda_0}{4\pi \epsilon_0} \lr{ \frac{ 1 + \frac{b – z}{\sqrt{ \rho^2 + (b-z)^2 }} }{ b-z + \sqrt{ \rho^2 + (b-z)^2 } } \frac{ 1 + \frac{a – z}{\sqrt{ \rho^2 + (a-z)^2 }} }{ a-z + \sqrt{ \rho^2 + (a-z)^2 } } } \\ &= \frac{\lambda_0}{4\pi \epsilon_0} \lr{ \inv{\sqrt{ \rho^2 + (b-z)^2 }} -\inv{\sqrt{ \rho^2 + (a-z)^2 }} }, \end{aligned} and \label{eqn:lineCharge:440} \begin{aligned} -\PD{\rho}{} \phi &= -\frac{\lambda_0}{4\pi \epsilon_0} \lr{ \frac{ \frac{\rho}{\sqrt{ \rho^2 + (b-z)^2 }} }{ b-z + \sqrt{ \rho^2 + (b-z)^2 } } \frac{ \frac{\rho}{\sqrt{ \rho^2 + (a-z)^2 }} }{ a-z + \sqrt{ \rho^2 + (a-z)^2 } } } \\ &= -\frac{\lambda_0}{4\pi \epsilon_0} \lr{ \frac{\rho \lr{ -(b-z) + \sqrt{ \rho^2 + (b-z)^2 } }}{ \rho^2 \sqrt{ \rho^2 + (b-z)^2 } } \frac{\rho \lr{ -(a-z) + \sqrt{ \rho^2 + (a-z)^2 } }}{ \rho^2 \sqrt{ \rho^2 + (a-z)^2 } } } \\ &= \frac{\lambda_0}{4\pi \epsilon_0 \rho} \lr{ \frac{b-z}{\sqrt{ \rho^2 + (b-z)^2 }} -\frac{a-z}{\sqrt{ \rho^2 + (a-z)^2 }} } . \end{aligned} Putting the pieces together, the electric field is \label{eqn:lineCharge:460} \BE = \frac{\lambda_0}{4\pi \epsilon_0} \lr{ \frac{\rhocap}{\rho} \lr{ \frac{b-z}{\sqrt{ \rho^2 + (b-z)^2 }} -\frac{a-z}{\sqrt{ \rho^2 + (a-z)^2 }} } + \zcap \lr{ \inv{\sqrt{ \rho^2 + (b-z)^2 }} -\inv{\sqrt{ \rho^2 + (a-z)^2 }} } }. For has a PV limit of \ref{eqn:lineCharge:40} at $$z = 0$$, and also for the finite case, has the $$\zcap$$ field component that was obtained when the field was obtained by direct integration. ### Conclusions • We have to evaluate the potential at all points in space, not just on the axis that we evaluate the field on (should we choose to do so). • In this case, we found that it was not directly meaningful to take the limit of a potential distribution. We can, however, compute the field from a potential for a finite charge distribution, take the limit of that field, and then calculate the corresponding potential for the infinite distribution. Is there a more robust mechanism that can be used to directly calculate the potential for an infinite charge distribution, instead of calculating the potential from the field of such an infinite distribution? I think that were things go wrong is that the integral of \ref{eqn:lineCharge:180} does not apply to charge distributions that are not finite on the infinite range $$z \in [-\infty, \infty]$$. That solution was obtained by utilizing an all-space Green’s function, and the boundary term in that Green’s analysis was assumed to tend to zero. That isn’t the case when the charge distribution is $$\lambda_0 \delta( z )$$. # References [1] JD Jackson. Classical Electrodynamics. John Wiley and Sons, 2nd edition, 1975.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9842408299446106, "perplexity": 3421.3600847929515}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583514162.67/warc/CC-MAIN-20181021161035-20181021182535-00183.warc.gz"}
https://physics.stackexchange.com/questions/321764/scalar-field-theories	# Scalar Field Theories The Lagrangian density for a single real scalar field theory is $$\mathcal{L}=\frac{1}{2}(\partial_{\mu}\phi)^{2}-V(\phi)$$ I have often seen this written $$\mathcal{L}=\frac{1}{2}\partial_{\mu}\phi\partial^{\mu}\phi-V(\phi)$$ which appears to differ in the kinetic term. Specifically $$(\partial_{\mu}\phi)^{2}=(\partial_{\mu}\phi)(\partial^{\mu}\phi)\neq\partial_{\mu}\phi\partial^{\mu}\phi=(\partial_{\mu}\phi)(\partial^{\mu}\phi)+\phi\partial_{\mu}\partial^{\mu}\phi$$ where the product rule has been used in the last equality. Is this just sloppy notation (which is acceptable because only first derivatives in the field are considered anyway), or is my maths very bad? • $\partial_\mu \phi \partial^\mu \phi$ always means $(\partial_{\mu}\phi)(\partial^{\mu}\phi)$. I have never seen it mean $\partial_\mu ( \phi \partial^\mu \phi )$ – Prahar Mar 27 '17 at 17:57 • You seem to think the implicit bracketing in $\partial_\mu \phi \partial^\mu \phi$ is $\partial_\mu (\phi\partial^\mu \phi)$. Why? – ACuriousMind Mar 27 '17 at 17:57 • @ACuriousMind If I had $x(t)$, $y(t)$ and $z(t)$ then given $\frac{d}{dt}xyz$ I would assume it meant $\frac{d}{dt}(xyz)$ and not $(\frac{d}{dt}x)(yz)$, so I've used that logic here... – Watw Mar 27 '17 at 18:00 ## 1 Answer 1. The notations $(\partial\phi)^{2}$ and $(\partial_{\mu}\phi)^{2}$ are shorthands for $(\partial_{\mu}\phi)g^{\mu\nu}(\partial_{\nu}\phi)$, where $g^{\mu\nu}$ is the inverse metric tensor. 2. Generally speaking, different authors use different notation concerning how far derivatives act to the right. When in doubt, it is a good idea to insert extra parentheses or spaces in the notation. See also this related Phys.SE post. 3. However, in the specific context of OP's kinetic term $\partial_{\mu}\phi\partial^{\mu}\phi$, it seems universally accepted that it is supposed to mean $(\partial_{\mu}\phi)\partial^{\mu}\phi$ as opposed to $\partial_{\mu}(\phi\partial^{\mu}\phi)$.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 3, "x-ck12": 0, "texerror": 0, "math_score": 0.9862728118896484, "perplexity": 268.42130009848313}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875145676.44/warc/CC-MAIN-20200222115524-20200222145524-00469.warc.gz"}
https://worldwidescience.org/topicpages/n/net+charge+transfer.html	#### Sample records for net charge transfer 1. Net charge fluctuations and local charge compensation International Nuclear Information System (INIS) Fu Jinghua 2006-01-01 We propose net charge fluctuation as a measure of local charge correlation length. It is demonstrated that, in terms of a schematic multiperipheral model, net charge fluctuation satisfies the same Quigg-Thomas relation as satisfied by charge transfer fluctuation. Net charge fluctuations measured in finite rapidity windows depend on both the local charge correlation length and the size of the observation window. When the observation window is larger than the local charge correlation length, the net charge fluctuation only depends on the local charge correlation length, while forward-backward charge fluctuations always have strong dependence on the observation window size. Net charge fluctuations and forward-backward charge fluctuations measured in the present heavy ion experiments show characteristic features similar to those from multiperipheral models. But the data cannot all be understood within this simple model 2. The net charge at interfaces between insulators International Nuclear Information System (INIS) Bristowe, N C; Littlewood, P B; Artacho, Emilio 2011-01-01 The issue of the net charge at insulating oxide interfaces is briefly reviewed with the ambition of dispelling myths of such charges being affected by covalency and related charge density effects. For electrostatic analysis purposes, the net charge at such interfaces is defined by the counting of discrete electrons and core ion charges, and by the definition of the reference polarization of the separate, unperturbed bulk materials. The arguments are illustrated for the case of a thin film of LaAlO 3 over SrTiO 3 in the absence of free carriers, for which the net charge is exactly 0.5e per interface formula unit, if the polarization response in both materials is referred to zero bulk values. Further consequences of the argument are extracted for structural and chemical alterations of such interfaces, in which internal rearrangements are distinguished from extrinsic alterations (changes of stoichiometry, redox processes), only the latter affecting the interfacial net charge. The arguments are reviewed alongside the proposal of Stengel and Vanderbilt (2009 Phys. Rev. B 80 241103) of using formal polarization values instead of net interfacial charges, based on the interface theorem of Vanderbilt and King-Smith (1993 Phys. Rev. B 48 4442-55). Implications for non-centrosymmetric materials are discussed, as well as for interfaces for which the charge mismatch is an integer number of polarization quanta. (viewpoint) 3. Charge transfer in astrophysical nebulae International Nuclear Information System (INIS) Shields, G.A. 1990-01-01 Charge transfer has become a standard ingredient in models of ionized nebulae, supernovae remnants and active galactic nuclei. Charge transfer rate coefficients and the physics of ionized nebulae are considered. Charge transfer is applied to the ionization structure and line emission of ionized nebulae. Photoionized nebulae observations are used to test theoretical predictions of charge transfer rates. (author) 4. Intramolecular Energy Transfer, Charge Transfer & Hydrogen Bond Ultrafast Dynamics of Chemical Reactions in Condensed Phase: Intramolecular Energy Transfer, Charge Transfer & Hydrogen Bond · PowerPoint Presentation · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19. 5. Charge Transfer into Aqueous Droplets via Kilovolt Potentials Science.gov (United States) Hamlin, B. S.; Rosenberg, E. R.; Ristenpart, W. D. 2012-11-01 When an aqueous droplet immersed in an insulating oil contacts an electrified surface, the droplet acquires net charge. For sufficiently large field strengths, the charged droplet is driven back and forth electrophoretically between the electrodes, in essence bouncing'' between them. Although it is clear that the droplet acquires charge, the underlying mechanism controlling the charge transfer process has been unclear. Here we demonstrate that the chemical species present in the droplet strongly affect the charge transfer process into the drop. Using two independent charge measurement techniques, high speed video velocimetry and direct current measurement, we show that the charge acquired during contact is strongly influenced by the droplet pH. We also provide physical evidence that the electrodes undergo electroplating or corrosion for droplets with appropriate chemical species present. Together, the observations strongly suggest that electrochemical reactions govern the charge transfer process into the droplet. 6. Higher-moment measurements of net-kaon, net-charge and net-proton multiplicity distributions at STAR International Nuclear Information System (INIS) Sarkar, Amal 2014-01-01 In this paper, we report the measurements of the various moments, such as mean, standard deviation (σ), skewness (S) and kurtosis (κ) of the net-kaon, net-charge and net-proton multiplicity distributions at mid-rapidity in Au + Au collisions from √(s NN )=7.7 to 200 GeV with the STAR experiment at RHIC. This work has been done with the aim to locate the critical point on the QCD phase diagram. These moments and their products are related to the thermodynamic susceptibilities of conserved quantities such as net baryon number, net charge, and net strangeness as well as to the correlation length of the system which diverges in an ideal infinite thermodynamic system at the critical point. For a finite system, existing for a finite time, a non-monotonic behavior of these variables would indicate the presence of the critical point. Furthermore, we also present the moment products Sσ, κσ 2 of net-kaon, net-charge and net-proton multiplicity distributions as a function of collision centrality and energy. The energy and the centrality dependence of higher moments and their products have been compared with different models 7. Net charge of quark jets in (anti)neutrino interactions International Nuclear Information System (INIS) Teper, M. 1981-01-01 We analyse recent measurements of the net charges of quark jets in neutrino and antineutrino interactions. The data indicates that (i) the two quarks in the nucleon fragmentation region prefer to behave as a diquark rather than as a pair of independent quarks, and (ii) the struck quark does not appear to suffer any soft charge exchange of the kind that occurs when a valence quark inside a nucleon is slowed to x approx. O. (orig.) 8. Charge migration and charge transfer in molecular systems Directory of Open Access Journals (Sweden) Hans Jakob Wörner 2017-11-01 Full Text Available The transfer of charge at the molecular level plays a fundamental role in many areas of chemistry, physics, biology and materials science. Today, more than 60 years after the seminal work of R. A. Marcus, charge transfer is still a very active field of research. An important recent impetus comes from the ability to resolve ever faster temporal events, down to the attosecond time scale. Such a high temporal resolution now offers the possibility to unravel the most elementary quantum dynamics of both electrons and nuclei that participate in the complex process of charge transfer. This review covers recent research that addresses the following questions. Can we reconstruct the migration of charge across a molecule on the atomic length and electronic time scales? Can we use strong laser fields to control charge migration? Can we temporally resolve and understand intramolecular charge transfer in dissociative ionization of small molecules, in transition-metal complexes and in conjugated polymers? Can we tailor molecular systems towards specific charge-transfer processes? What are the time scales of the elementary steps of charge transfer in liquids and nanoparticles? Important new insights into each of these topics, obtained from state-of-the-art ultrafast spectroscopy and/or theoretical methods, are summarized in this review. 9. Spontaneous charged lipid transfer between lipid vesicles. Science.gov (United States) Richens, Joanna L; Tyler, Arwen I I; Barriga, Hanna M G; Bramble, Jonathan P; Law, Robert V; Brooks, Nicholas J; Seddon, John M; Ces, Oscar; O'Shea, Paul 2017-10-03 An assay to study the spontaneous charged lipid transfer between lipid vesicles is described. A donor/acceptor vesicle system is employed, where neutrally charged acceptor vesicles are fluorescently labelled with the electrostatic membrane probe Fluoresceinphosphatidylethanolamine (FPE). Upon addition of charged donor vesicles, transfer of negatively charged lipid occurs, resulting in a fluorescently detectable change in the membrane potential of the acceptor vesicles. Using this approach we have studied the transfer properties of a range of lipids, varying both the headgroup and the chain length. At the low vesicle concentrations chosen, the transfer follows a first-order process where lipid monomers are transferred presumably through the aqueous solution phase from donor to acceptor vesicle. The rate of transfer decreases with increasing chain length which is consistent with energy models previously reported for lipid monomer vesicle interactions. Our assay improves on existing methods allowing the study of a range of unmodified lipids, continuous monitoring of transfer and simplified experimental procedures. 10. Charge transfer in ionic systems International Nuclear Information System (INIS) Bacchus-Montabonel, M.C.; Tergiman, Y.S.; Vaeck, N.; Baloitcha, E.; Desouter-Lecomte, M. 2002-01-01 Charge transfer involving multiply charged ions in collision with atomic or molecular targets are determinant processes in controlled thermonuclear fusion research and astrophysical plasma. In such processes, an electron is generally captured in a excited state of the ion, followed by line emission. The observation of line intensities provides important information on the electron temperature, density and spacial distributions in the emitting region of the plasma. From a theoretical point of view, different approaches may be used with regard to the collisional energy range of the process. A semi-classical method is currently used at keV energies, but the description of very low-velocity processes requires a complete quantum mechanical treatment of the dynamics of both electrons and nuclei. The first approach extensively used is the resolution of the stationary close-coupling equations, but we have analyzed recently the efficiency of a time-dependent wave packet method which provides a clear and physical insight into the dynamics of the processes and may be particularly interesting for polyatomic systems since it allows the possibility of developing a fully quantal mechanical treatment for some degrees of freedom, the other ones being treated classically. The keV energy range treatment is presented on two examples pointing out the case of complex ion-atom collision systems, as well as the differences between ion-atom and ion-molecule mechanisms. In connection with translation energy spectroscopy experiments of McLaughlin et al in the 4-28 keV impact energy range, we present a complete ab-initio theoretical approach of the N 4+ (2s) 2 S + He system taking into account both single and double electron capture channels. This is an extremely complex collisional system which involves numerous channels with short range interactions and a very intricate interaction region may be observed for interatomic distances around R = 3.5 a.u.. In agreement with experimental data, the 11. Possible charge analogues of spin transfer torques in bulk superconductors Science.gov (United States) Garate, Ion 2014-03-01 Spin transfer torques (STT) occur when electric currents travel through inhomogeneously magnetized systems and are important for the motion of magnetic textures such as domain walls. Since superconductors are easy-plane ferromagnets in particle-hole (charge) space, it is natural to ask whether any charge duals of STT phenomena exist therein. We find that the superconducting analogue of the adiabatic STT vanishes in a bulk superconductor with a momentum-independent order parameter, while the superconducting counterpart of the nonadiabatic STT does not vanish. This nonvanishing superconducting torque is induced by heat (rather than charge) currents and acts on the charge (rather than spin) degree of freedom. It can become significant in the vicinity of the superconducting transition temperature, where it generates a net quasiparticle charge and alters the dispersion and linewidth of low-frequency collective modes. This work has been financially supported by Canada's NSERC. 12. Charge orders in organic charge-transfer salts International Nuclear Information System (INIS) Kaneko, Ryui; Valentí, Roser; Tocchio, Luca F; Becca, Federico 2017-01-01 Motivated by recent experimental suggestions of charge-order-driven ferroelectricity in organic charge-transfer salts, such as κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl, we investigate magnetic and charge-ordered phases that emerge in an extended two-orbital Hubbard model on the anisotropic triangular lattice at 3/4 filling. This model takes into account the presence of two organic BEDT-TTF molecules, which form a dimer on each site of the lattice, and includes short-range intramolecular and intermolecular interactions and hoppings. By using variational wave functions and quantum Monte Carlo techniques, we find two polar states with charge disproportionation inside the dimer, hinting to ferroelectricity. These charge-ordered insulating phases are stabilized in the strongly correlated limit and their actual charge pattern is determined by the relative strength of intradimer to interdimer couplings. Our results suggest that ferroelectricity is not driven by magnetism, since these polar phases can be stabilized also without antiferromagnetic order and provide a possible microscopic explanation of the experimental observations. In addition, a conventional dimer-Mott state (with uniform density and antiferromagnetic order) and a nonpolar charge-ordered state (with charge-rich and charge-poor dimers forming a checkerboard pattern) can be stabilized in the strong-coupling regime. Finally, when electron–electron interactions are weak, metallic states appear, with either uniform charge distribution or a peculiar 12-site periodicity that generates honeycomb-like charge order. (paper) 13. Graphene Charge Transfer, Spectroscopy, and Photochemical Reactions Energy Technology Data Exchange (ETDEWEB) Brus, Louis [Columbia Univ., New York, NY (United States) 2017-01-31 This project focused on the special electronic and optical properties of graphene and adsorbed molecular species. Graphene makes an excellent substrate for current collection in nanostructured photovoltaic designs. Graphene is almost transparent, and can be used as a solar cell window. It also has no surface states, and thus current is efficiently transported over long distances. Progress in graphene synthesis indicates that there will soon be practical methods for making large pieces of graphene for devices. We now need to understand exactly what happens to both ground state and electronically excited molecules and Qdots near graphene, if we are going to use them to absorb light in a nano-structured photovoltaic device using graphene to collect photocurrent. We also need to understand how to shift the graphene Fermi level, to optimize the kinetics of electron transfer to graphene. And we need to learn how to convert local graphene areas to semiconductor structure, to make useful spatially patterned graphenes. In this final report, we describe how we addressed these goals. We explored the question of possible Surface Enhanced Raman spectroscopy from molecular Charge Transfer onto Graphene substrates. We observed strong hole doping of graphene by adsorbed halogens as indicated by the shift of the graphene G Raman band. In the case of iodine adsorption, we also observed the anionic species made by hole doping. At low frequency in the Raman spectrum, we saw quite intense lines from I3- and I5- , suggesting possible SERS. We reported on Fresnel calculations on this thin film system, which did not show any net electromagnetic field enhancement. 14. Symmetric charge transfer cross section of uranium International Nuclear Information System (INIS) Shibata, Takemasa; Ogura, Koichi 1995-03-01 Symmetric charge transfer cross section of uranium was calculated under consideration of reaction paths. In the charge transfer reaction a d 3/2 electron in the U atom transfers into the d-electron site of U + ( 4 I 9/2 ) ion. The J value of the U atom produced after the reaction is 6, 5, 4 or 3, at impact energy below several tens eV, only resonant charge transfer in which the product atom is ground state (J=6) takes place. Therefore, the cross section is very small (4-5 x 10 -15 cm 2 ) compared with that considered so far. In the energy range of 100-1000eV the cross section increases with the impact energy because near resonant charge transfer in which an s-electron in the U atom transfers into the d-electron site of U + ion. Charge transfer cross section between U + in the first excited state (289 cm -1 ) and U in the ground state was also obtained. (author) 15. Influence of kinematic cuts on the net charge distribution Energy Technology Data Exchange (ETDEWEB) Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Institut für Theoretische Physik, Goethe Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Oliinychenko, Dmytro [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine); Steinheimer, Jan [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Bleicher, Marcus [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Institut für Theoretische Physik, Goethe Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany) 2016-12-15 The higher moments of the net charge distributions, e.g. the skewness and kurtosis, are studied within an infinite hadronic matter calculation in a transport approach. By dividing the box into several parts, the volume dependence of the fluctuations is investigated. After confirming that the initial distributions follow the expectations from a binomial distribution, the influence of quantum number conservation in this case the net charge in the system on the higher moments is evaluated. For this purpose, the composition of the hadron gas is adjusted and only pions and ρ mesons are simulated to investigate the charge conservation effect. In addition, the effect of imposing kinematic cuts in momentum space is analysed. The role of resonance excitations and decays on the higher moments can also be studied within this model. This work is highly relevant to understand the experimental measurements of higher moments obtained in the RHIC beam energy scan and their comparison to lattice results and other theoretical calculations assuming infinite matter. 16. First result of net-charge jet-correlations from STAR International Nuclear Information System (INIS) Wang, Q. 2011-01-01 We presented results on azimuthal correlation of net-charge with high ρ T trigger particles. It is found that the net-charge correlation shape is similar to that of total-charge. On the near-side, the net-charge and total-charge ρ T spectra have similar shape and both are harder than the inclusives. On the away-side, the correlated spectra are not much harder than the inclusives, and the net-charge/total-charge ratio increases with ρ T and is similar to the inclusive ratio. (author) 17. Bond charges and electronic charge transfer in ternary semiconductors International Nuclear Information System (INIS) Pietsch, U. 1986-01-01 By means of a simple molecule-theoretic model of 'linear superposition of two-electron molecules' the bond charges between nearest neighbours and the effective charges of ions are calculated for ternary zinc-blende structure alloys as well as chalcopyrite semiconductors. Taking into account both, the charge transfer among the ions caused by the differences of electronegativities of atoms used and between the bonds created by the internal stress of the lattice a nearly unvaried averaged bond charge amount of the alloy is found, but rather dramatically changed local bond charge parameters in comparison with the respective values of binary compounds used. This fact should influence the noncentral force interaction in such semiconductors. (author) 18. Charge transfer reactions in Xe plasma expansion International Nuclear Information System (INIS) Jiao, C. Q.; Garscadden, A.; Ganguly, B. N. 2007-01-01 Charge transfer reactions of fast Xe ions with hydrocarbons including methane (CH 4 ), ethene (C 2 H 4 ), and propane (C 3 H 8 ) are studied by adding these hydrocarbon gases into a cross flowing Xe plasma expansion. Branching ratios and relative reaction rates for the charge transfers of fast Xe + with each of the three hydrocarbon gases are measured under different rf powers of the inductively coupled Xe discharge. For CH 4 /Xe system, we find that fast Xe + reacts readily with CH 4 generating CH 4 + and CH 3 + in a ratio of 1:0.56, with an estimated rate coefficient of (2.3±0.3)x10 -10 cm 3 /s at 75 W rf power which slowly increases to (2.9±0.3)x10 -10 cm 3 /s at 250 W (error bars reflect only the uncertainties due to the unknown extent of the ion recombination that follows the charge transfer reaction). These observed charge transfer reactions are made possible by the kinetically excited Xe ions produced by free expansion of the plasma. For the C 2 H 4 /Xe system product ions C 2 H 4 + and C 2 H 2 + are observed, and for C 3 H 8 /Xe, C 2 H 4 + and C 2 H 5 + and minor product ions including C 2 H 2 + and C 3 H 7 + are observed 19. NET: an inter-computer file transfer command International Nuclear Information System (INIS) Burris, R.D. 1978-05-01 The NET command was defined and supported in order to facilitate file transfer between computers. Among the goals of the implementation were greatest possible ease of use, maximum power (i.e., support of a diversity of equipment and operations), and protection of the operating system 20. Net-baryon-, net-proton-, and net-charge kurtosis in heavy-ion collisions within a relativistic transport approach International Nuclear Information System (INIS) Nahrgang, Marlene; Schuster, Tim; Stock, Reinhard; Mitrovski, Michael; Bleicher, Marcus 2012-01-01 We explore the potential of net-baryon, net-proton and net-charge kurtosis measurements to investigate the properties of hot and dense matter created in relativistic heavy-ion collisions. Contrary to calculations in a grand-canonical ensemble we explicitly take into account exact electric and baryon charge conservation on an event-by-event basis. This drastically limits the width of baryon fluctuations. A simple model to account for this is to assume a grand-canonical distribution with a sharp cut-off at the tails. We present baseline predictions of the energy dependence of the net-baryon, net-proton and net-charge kurtosis for central (b≤2.75 fm) Pb+Pb/Au+Au collisions from E lab =2A GeV to √(s NN )=200 GeV from the UrQMD model. While the net-charge kurtosis is compatible with values around zero, the net-baryon number decreases to large negative values with decreasing beam energy. The net-proton kurtosis becomes only slightly negative for low √(s NN ). (orig.) 1. Does charge transfer correlate with ignition probability? International Nuclear Information System (INIS) Holdstock, Paul 2008-01-01 Flammable or explosive atmospheres exist in many industrial environments. The risk of ignition caused by electrostatic discharges is very real and there has been extensive study of the incendiary nature of sparks and brush discharges. It is clear that in order to ignite a gas, an amount of energy needs to be delivered to a certain volume of gas within a comparatively short time. It is difficult to measure the energy released in an electrostatic discharge directly, but it is possible to approximate the energy in a spark generated from a well defined electrical circuit. The spark energy required to ignite a gas, vapour or dust cloud can be determined by passing such sparks through them. There is a relationship between energy and charge in a capacitive circuit and so it is possible to predict whether or not a spark discharge will cause an ignition by measuring the charge transferred in the spark. Brush discharges are in many ways less well defined than sparks. Nevertheless, some work has been done that has established a relationship between charge transferred in brush discharges and the probability of igniting a flammable atmosphere. The question posed by this paper concerns whether such a relationship holds true in all circumstances and if there is a universal correlation between charge transfer and ignition probability. Data is presented on discharges from textile materials that go some way to answering this question. 2. Computational Approach to Electron Charge Transfer Reactions DEFF Research Database (Denmark) Jónsson, Elvar Örn -molecular mechanics scheme, and tools to analyse statistical data and generate relative free energies and free energy surfaces. The methodology is applied to several charge transfer species and reactions in chemical environments - chemical in the sense that solvent, counter ions and substrate surfaces are taken...... in to account - which directly influence the reactants and resulting reaction through both physical and chemical interactions. All methods are though general and can be applied to different types of chemistry. First, the basis of the various theoretical tools is presented and applied to several test systems...... and asymmetric charge transfer reactions between several first-row transition metals in water. The results are compared to experiments and rationalised with classical analytic expressions. Shortcomings of the methods are accounted for with clear steps towards improved accuracy. Later the analysis is extended... 3. Impact of charge-transfer excitons in regioregular polythiophene on the charge separation at polythiophene-fullerene heterojunctions Science.gov (United States) Polkehn, M.; Tamura, H.; Burghardt, I. 2018-01-01 This study addresses the mechanism of ultrafast charge separation in regioregular oligothiophene-fullerene assemblies representative of poly-3-hexylthiophene (P3HT)-[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) heterojunctions, with special emphasis on the inclusion of charge transfer excitons in the oligothiophene phase. The formation of polaronic inter-chain charge separated species in highly ordered oligothiophene has been demonstrated in recent experiments and could have a significant impact on the net charge transfer to the fullerene acceptor. The present approach combines a first-principles parametrized multi-site Hamiltonian, based on time-dependent density functional theory calculations, with accurate quantum dynamics simulations using the multi-layer multi-configuration time-dependent Hartree method. Quantum dynamical studies are carried out for up to 182 electronic states and 112 phonon modes. The present analysis follows up on our previous study of (Huix-Rotllant et al 2015 J. Phys. Chem. Lett. 6 1702) and significantly expands the scope of this analysis by including the dynamical role of charge transfer excitons. Our investigation highlights the pronounced mixing of photogenerated Frenkel excitons with charge transfer excitons in the oligothiophene domain, and the opening of new transfer channels due the creation of such charge-separated species. As a result, it turns out that the interfacial donor/acceptor charge transfer state can be largely circumvented due to the presence of charge transfer excitons. However, the latter states in turn act as a trap, such that the free carrier yield observed on ultrafast time scales is tangibly reduced. The present analysis underscores the complexity of the transfer pathways at P3HT-PCBM type junctions. 4. Effect of net surface charge on particle sizing and material recognition by using phase Doppler anemometry International Nuclear Information System (INIS) Zhou Jun; Xie Li 2011-01-01 By taking net surface charge into consideration, the scattering field of particles illuminated by dual laser beams of phase Doppler anemometry (PDA) is computed based on Mie's theory, and the effect of net surface charge on the phase-diameter relationship and the phase ratio is studied. It is found that the phase-diameter relationship and the relationship between the phase ratio and the refractive index of charged particles could be significantly different from those of uncharged particles, which would lead to errors in particle sizing and the measurement of refractive indices. A method of recognizing charged particles and determining the value of their surface conductivity, which is related to net surface charge, is proposed by utilizing the effect of net surface charge on the measurement of refractive indices using PDA. 5. Effect of net surface charge on particle sizing and material recognition by using phase Doppler anemometry Energy Technology Data Exchange (ETDEWEB) Zhou Jun; Xie Li 2011-01-20 By taking net surface charge into consideration, the scattering field of particles illuminated by dual laser beams of phase Doppler anemometry (PDA) is computed based on Mie's theory, and the effect of net surface charge on the phase-diameter relationship and the phase ratio is studied. It is found that the phase-diameter relationship and the relationship between the phase ratio and the refractive index of charged particles could be significantly different from those of uncharged particles, which would lead to errors in particle sizing and the measurement of refractive indices. A method of recognizing charged particles and determining the value of their surface conductivity, which is related to net surface charge, is proposed by utilizing the effect of net surface charge on the measurement of refractive indices using PDA. 6. Charge transfer in gas electron multipliers Energy Technology Data Exchange (ETDEWEB) Ottnad, Jonathan; Ball, Markus; Ketzer, Bernhard; Ratza, Viktor; Razzaghi, Cina [HISKP, Bonn University, Nussallee 14-16, D-53115 Bonn (Germany) 2015-07-01 In order to efficiently employ a Time Projection Chamber (TPC) at interaction rates higher than ∝1 kHz, as foreseen e.g. in the ALICE experiment (CERN) and at CB-ELSA (Bonn), a continuous operation and readout mode is required. A necessary prerequisite is to minimize the space charge coming from the amplification system and to maintain an excellent spatial and energy resolution. Unfortunately these two goals can be in conflict to each other. Gas Electron Multipliers (GEM) are one candidate to fulfill these requirements. It is necessary to understand the processes within the amplification structure to find optimal operation conditions. To do so, we measure the charge transfer processes in and between GEM foils with different geometries and field configurations, and use an analytical model to describe the results. This model can then be used to predict and optimize the performance. The talk gives the present status of the measurements and describes the model. 7. Ultrafast Charge Photogeneration in MEH-PPV Charge-Transfer Complexes NARCIS (Netherlands) Bakulin, Artem A.; Paraschuk, Dmitry Yu; Pshenichnikov, Maxim S.; van Loosdrecht, Paul H. M.; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E; Schoenlein, RW 2009-01-01 Visible-pump - IR-probe spectroscopy is used to study the ultrafast charge dynamics in MEH-PPV based charge-transfer complexes and donor-acceptor blends. Transient anisotropy of the polymer polaron band provides invaluable insights into excitation localisation and charge-transfer pathways. 8. Charge-transfer spectra of tetravalent lanthanide ions in oxides NARCIS (Netherlands) The charge-transfer spectra of Ce4+, Pr4+ and Tb4+ in a number of oxides are reported. It is noted that the position of the first charge-transfer band is fixed for the metal ion in an oxygen coordination of VI, but varies in VIII coordination as a function of the host lattice. It is argued that this 9. Characterisation of a CMOS charge transfer device for TDI imaging International Nuclear Information System (INIS) Rushton, J.; Holland, A.; Stefanov, K.; Mayer, F. 2015-01-01 The performance of a prototype true charge transfer imaging sensor in CMOS is investigated. The finished device is destined for use in TDI applications, especially Earth-observation, and to this end radiation tolerance must be investigated. Before this, complete characterisation is required. This work starts by looking at charge transfer inefficiency and then investigates responsivity using mean-variance techniques 10. Determination of net atomic charges in anthraquinone by means of 5-h X-ray diffraction experiment Czech Academy of Sciences Publication Activity Database Šlouf, Miroslav 2002-01-01 Roč. 611, 1-3 (2002), s. 139-146 ISSN 0022-2860 R&D Projects: GA ČR GA203/99/M037 Institutional research plan: CEZ:AV0Z4050913 Keywords : net charges * net atomic charges * charge density analysis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.122, year: 2002 11. Charge Transfer and Catalysis at the Metal Support Interface Energy Technology Data Exchange (ETDEWEB) Baker, Lawrence Robert [Univ. of California, Berkeley, CA (United States) 2012-07-31 Kinetic, electronic, and spectroscopic characterization of model Pt–support systems are used to demonstrate the relationship between charge transfer and catalytic activity and selectivity. The results show that charge flow controls the activity and selectivity of supported metal catalysts. This dissertation builds on extensive existing knowledge of metal–support interactions in heterogeneous catalysis. The results show the prominent role of charge transfer at catalytic interfaces to determine catalytic activity and selectivity. Further, this research demonstrates the possibility of selectively driving catalytic chemistry by controlling charge flow and presents solid-state devices and doped supports as novel methods for obtaining electronic control over catalytic reaction kinetics. 12. Transfer Pricing; Charging of head office costs Energy Technology Data Exchange (ETDEWEB) Andersen, Joergen 1998-07-01 The key issues discussed in this presentation are (1) What are head office costs?, (2) Why is the charging an area of concern for international companies?, (3) Which part of head office costs should be charged?, (4) OECD guidelines on charging. Head office costs are classified as Shareholder costs, Stewardship costs, Costs related to a specific subsidiary or group of subsidiaries (on call), and Costs related to operational activities in the parent company. The OECD reports of 1984 and 1996 are discussed. In Norsk Hydro's experience, the practising of the OECD guidelines by national authorities are confusing and not consistent over time or across borders. To get a better understanding of how charging of corporate head office costs are dealt with on an international level, Norsk Hydro asked Deloitte and Touche in London to carry out a study on international companies' behaviour. Their conclusions are included. 13. Effects of acid concentration on intramolecular charge transfer ... rate. Time-dependent density functional theory calculations have been performed to understand the observed spectroscopic results. Keywords. Intramolecular charge transfer; absorption and fluorescence; time resolved fluorescence measurements; acid concentration dependence; time-dependent density functional theory. 14. Charge-transfer collisions for polarized ion sources International Nuclear Information System (INIS) Schlachter, A.S. 1983-06-01 Charge-transfer processes relevant to polarized ion sources are discussed and results are summarized. The primary atom discussed is hydrogen, with particulr emphasis on H - formation. Heavier negative ions are briefly discussed 15. First study of the negative binomial distribution applied to higher moments of net-charge and net-proton multiplicity distributions International Nuclear Information System (INIS) Tarnowsky, Terence J.; Westfall, Gary D. 2013-01-01 A study of the first four moments (mean, variance, skewness, and kurtosis) and their products (κσ 2 and Sσ) of the net-charge and net-proton distributions in Au + Au collisions at √(s NN )=7.7–200 GeV from HIJING simulations has been carried out. The skewness and kurtosis and the collision volume independent products κσ 2 and Sσ have been proposed as sensitive probes for identifying the presence of a QCD critical point. A discrete probability distribution that effectively describes the separate positively and negatively charged particle (or proton and anti-proton) multiplicity distributions is the negative binomial (or binomial) distribution (NBD/BD). The NBD/BD has been used to characterize particle production in high-energy particle and nuclear physics. Their application to the higher moments of the net-charge and net-proton distributions is examined. Differences between κσ 2 and a statistical Poisson assumption of a factor of four (for net-charge) and 40% (for net-protons) can be accounted for by the NBD/BD. This is the first application of the properties of the NBD/BD to describe the behavior of the higher moments of net-charge and net-proton distributions in nucleus–nucleus collisions 16. Charge transfers in complex transition metal alloys (Ti2Fe) International Nuclear Information System (INIS) Abramovici, G. 1998-01-01 We introduce a new non-orthogonal tight-binding model, for complex alloys, in which electronic structure is characterized by charge transfers. We give the analytic calculation of a charge transfer, in which overlapping two-center terms are rigorously taken into account. Then, we apply numerically this result to an approximant phase of a quasicrystal of Ti 2 Fe alloy. This model is more particularly adapted to transition metals, and gives realistic densities of states. (orig.) 17. Charge transfer induced activity of graphene for oxygen reduction International Nuclear Information System (INIS) Shen, Anli; Xia, Weijun; Dou, Shuo; Wang, Shuangyin; Zhang, Lipeng; Xia, Zhenhai 2016-01-01 Tetracyanoethylene (TCNE), with its strong electron-accepting ability, was used to dope graphene as a metal-free electrocatalyst for the oxygen reduction reaction (ORR). The charge transfer process was observed from graphene to TCNE by x-ray photoelectron spectroscopy and Raman characterizations. Our density functional theory calculations found that the charge transfer behavior led to an enhancement of the electrocatalytic activity for the ORR. (paper) 18. Controlling the net charge on a nanoparticle optically levitated in vacuum Science.gov (United States) Frimmer, Martin; Luszcz, Karol; Ferreiro, Sandra; Jain, Vijay; Hebestreit, Erik; Novotny, Lukas 2017-06-01 Optically levitated nanoparticles in vacuum are a promising model system to test physics beyond our current understanding of quantum mechanics. Such experimental tests require extreme control over the dephasing of the levitated particle's motion. If the nanoparticle carries a finite net charge, it experiences a random Coulomb force due to fluctuating electric fields. This dephasing mechanism can be fully excluded by discharging the levitated particle. Here, we present a simple and reliable technique to control the charge on an optically levitated nanoparticle in vacuum. Our method is based on the generation of charges in an electric discharge and does not require additional optics or mechanics close to the optical trap. 19. Phonons and charge-transfer excitations in HTS superconductors International Nuclear Information System (INIS) Bishop, A.R. 1989-01-01 Some of the experimental and theoretical evidence implicating phonons and charge-transfer excitations in HTS superconductors is reviewed. It is suggested that superconductivity may be driven by a synergistic interplay of (anharmonic) phonons and electronic degrees of freedom (e.g., charge fluctuations, excitons). 47 refs., 5 figs 20. Theoretical treatment of charge transfer processes of relevance to astrophysics Energy Technology Data Exchange (ETDEWEB) Krstic, P.S.; Stancil, P.C.; Schultz, D.R. 1997-12-01 Charge transfer is an important process in many astrophysical and atmospheric environments. While numerous experimental and theoretical studies exist for H and He targets, data on other targets, particularly metals and molecules, are sparse. Using a variety of theoretical methods and computational techniques the authors are developing methods to estimate the cross sections for electron capture (charge transfer) in slow collisions of low charge state ions with heavy (Mg, Ca, Fe, Co, Ni and Zn) neutrals. In this ongoing work particular attention is paid to ascertaining the importance of double electron capture. 1. Theoretical treatment of charge transfer processes of relevance to astrophysics International Nuclear Information System (INIS) Krstic, P.S.; Stancil, P.C.; Schultz, D.R. 1997-12-01 Charge transfer is an important process in many astrophysical and atmospheric environments. While numerous experimental and theoretical studies exist for H and He targets, data on other targets, particularly metals and molecules, are sparse. Using a variety of theoretical methods and computational techniques the authors are developing methods to estimate the cross sections for electron capture (charge transfer) in slow collisions of low charge state ions with heavy (Mg, Ca, Fe, Co, Ni and Zn) neutrals. In this ongoing work particular attention is paid to ascertaining the importance of double electron capture 2. Collisional charging of individual submillimeter particles: Using ultrasonic levitation to initiate and track charge transfer Science.gov (United States) Lee, Victor; James, Nicole M.; Waitukaitis, Scott R.; Jaeger, Heinrich M. 2018-03-01 Electrostatic charging of insulating fine particles can be responsible for numerous phenomena ranging from lightning in volcanic plumes to dust explosions. However, even basic aspects of how fine particles become charged are still unclear. Studying particle charging is challenging because it usually involves the complexities associated with many-particle collisions. To address these issues, we introduce a method based on acoustic levitation, which makes it possible to initiate sequences of repeated collisions of a single submillimeter particle with a flat plate, and to precisely measure the particle charge in situ after each collision. We show that collisional charge transfer between insulators is dependent on the hydrophobicity of the contacting surfaces. We use glass, which we modify by attaching nonpolar molecules to the particle, the plate, or both. We find that hydrophilic surfaces develop significant positive charges after contacting hydrophobic surfaces. Moreover, we demonstrate that charging between a hydrophilic and a hydrophobic surface is suppressed in an acidic environment and enhanced in a basic one. Application of an electric field during each collision is found to modify the charge transfer, again depending on surface hydrophobicity. We discuss these results within the context of contact charging due to ion transfer, and we show that they lend strong support to O H- ions as the charge carriers. 3. Collisions of highly stripped ions at MeV energies in gas targets: charge transfer and ionization International Nuclear Information System (INIS) Schlachter, A.S. 1980-01-01 Cross sections have been measured for charge transfer and ionization in H 2 and rare-gas targets by fast, highly ionized carbon, iron, niobium, and lead ions in charge states +3 to +59, with energies in the range 0.1 to 4.8 MeV/amu. Experimental results are compared with classical-trajectory calculations; agreement is generally good. For a given target, the cross sections for net ionization reduce to a common curve when plotted as cross section divided by charge state versus energy per nucleon divided by charge state 4. The Properties of the Space-Charge and Net Current Density in Magnetized Plasmas International Nuclear Information System (INIS) Hatami, M. M. 2013-01-01 A hydrodynamic model is used to investigate the properties of positive space-charge and net current density in the sheath region of magnetized, collisional plasmas with warm positive ions. It is shown that an increase in the ion-neutral collision frequency, as well as the magnitude of the external magnetic field, leads to an increase in the net current density across the sheath region. The results also show that the accumulation of positive ions in the sheath region increases by increasing the ion-neutral collision frequency and the magnitude of the magnetic field. In addition, it is seen that an increase in the positive ion temperatures causes a decrease in the accumulation of positive ions and the net current density in the sheath region. (basic plasma phenomena) 5. Chemical sensors based on surface charge transfer Science.gov (United States) Mohtasebi, Amirmasoud; Kruse, Peter 2018-02-01 The focus of this review is an introduction to chemiresistive chemical sensors. The general concept of chemical sensors is briefly introduced, followed by different architectures of chemiresistive sensors and relevant materials. For several of the most common systems, the fabrication of the active materials used in such sensors and their properties are discussed. Furthermore, the sensing mechanism, advantages, and limitations of each group of chemiresistive sensors are briefly elaborated. Compared to electrochemical sensors, chemiresistive sensors have the key advantage of a simpler geometry, eliminating the need for a reference electrode. The performance of bulk chemiresistors can be improved upon by using freestanding ultra-thin films (nanomaterials) or field effect geometries. Both of those concepts have also been combined in a gateless geometry, where charge transport though a percolation network of nanomaterials is modulated via adsorbate doping. 6. Beam-energy and system-size dependence of dynamical net charge fluctuations Czech Academy of Sciences Publication Activity Database Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D.R.; Bellwied, R.; Benedosso, F.; Betancourt, M.J.; Betts, R. R.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielčík, Jaroslav; Bielčíková, Jana; Biritz, B.; Bland, L.C.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bruna, E.; Bueltmann, S.; Burton, T. P.; Bysterský, Michal; Cai, X.Z.; Caines, H.; Sanchez, M.C.D.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M.C.; Chajecki, Z.; Chaloupka, Petr; Chattopadhyay, S.; Chen, H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K.E.; Christie, W.; Clarke, R.F.; Codrington, M.J.M.; Corliss, R.; Cormier, T.M.; Coserea, R. M.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; De Silva, L.C.; Dedovich, T. G.; DePhillips, M.; Derevschikov, A.A.; de Souza, R.D.; Didenko, L.; Djawotho, P.; Dunlop, J.C.; Mazumdar, M.R.D.; Edwards, W.R.; Efimov, L.G.; Elhalhuli, E.; Elnimr, M.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Gangaharan, D.R.; Garcia-Solis, E.J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y.N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S.M.; Guimaraes, K.S.F.F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Hofman, D.J.; Hollis, R.S.; Huang, H.Z.; Humanic, T.J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W.W.; Jakl, Pavel; Jena, C.; Jin, F.; Jones, C.L.; Jones, P.G.; Joseph, J.; Judd, E.G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitán, Jan; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V.Yu.; Kikola, D.P.; Kiryluk, J.; Kisiel, A.; Klein, S.R.; Knospe, A.G.; Kocoloski, A.; Koetke, D.D.; Kopytine, M.; Korsch, W.; Kotchenda, L.; Kushpil, Vasilij; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Krus, M.; Kuhn, C.; Kumar, L.; Kurnadi, P.; Lamont, M.A.C.; Landgraf, J.M.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednický, Richard; Lee, Ch.; Lee, J.H.; Leight, W.; LeVine, M.J.; Li, N.; Li, C.; Li, Y.; Lin, G.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W.J.; Longacre, R.S.; Love, W.A.; Lu, Y.; Ludlam, T.; Ma, G.L.; Ma, Y.G.; Mahapatra, D.P.; Majka, R.; Mall, O.I.; Mangotra, L.K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H.S.; Matulenko, Yu.A.; McShane, T.S.; Meschanin, A.; Milner, R.; Minaev, N.G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D.A.; Munhoz, M. G.; Nandi, B.K.; Nattrass, C.; Nayak, T. K.; Nelson, J.M.; Netrakanti, P.K.; Ng, M.J.; Nogach, L.V.; Nurushev, S.B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B.S.; Pal, S.K.; Pandit, Y.; Panebratsev, Y.; Panitkin, S.Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S.C.; Poljak, N.; Poskanzer, A.M.; Potukuchi, B.V.K.S.; Prindle, D.; Pruneau, C.; Pruthi, N.K.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R.L.; Redwine, R.; Reed, R.; Ridiger, A.; Ritter, H.G.; Roberts, J.B.; Rogachevskiy, O.V.; Romero, J.L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M.J.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R.P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S.S.; Shi, X.H.; Sichtermann, E.P.; Simon, F.; Singaraju, R.N.; Skoby, M.J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Spinka, H.M.; Srivastava, B.; Stadnik, A.; Stanislaus, T.D.S.; Staszak, D.; Strikhanov, M.; Stringfellow, B.; Suaide, A.A.P.; Suarez, M.C.; Subba, N.L.; Šumbera, Michal; Sun, X.M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T.J.M.; de Toledo, A. S.; Takahashi, J.; Tang, A.H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J.H.; Tian, J.; Timmins, A.R.; Timoshenko, S.; Tokarev, M. V.; Trainor, T.A.; Tram, V.N.; Trattner, A.L.; Trentalange, S.; Tribble, R. E.; Tsai, O.D.; Ulery, J.; Ullrich, T.; Underwood, D.G.; Van Buren, G.; van Leeuwen, M.; Vander Molen, A.M.; Vanfossen, J.A.; Varma, R.; Vasconcelos, G.S.M.; Vasilevski, I.M.; Vasiliev, A. N.; Videbaek, F.; Vigdor, S.E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S.A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, J.S.; Wang, Q.; Wang, X.; Wang, X.L.; Wang, Y.; Webb, G.; Webb, J.C.; Westfall, G.D.; Whitten, C.; Wieman, H.; Wissink, S.W.; Witt, R.; Wu, Y.; Tlustý, David; Xie, W.; Xu, N.; Xu, Q.H.; Xu, Y.; Xu, Z.; Yang, P.; Yepes, P.; Yip, K.; Yoo, I.K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, S.; Zhang, W.M.; Zhang, X.P.; Zhang, Y.; Zhang, Z.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J.X. 2009-01-01 Roč. 79, č. 2 (2009), 024906/1-024906/14 ISSN 0556-2813 R&D Projects: GA ČR GA202/07/0079; GA MŠk LC07048 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100502 Keywords : NET CHARGE * DYNAMICAL FLUCTUATIONS * HEAVY-ION COLLISIONS Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.477, year: 2009 7. Charge transfer cross sections for dysprosium and cerium Energy Technology Data Exchange (ETDEWEB) Adachi, Hajime; Tamura, Koji; Okazaki, Tetsuji; Shibata, Takemasa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment 1998-06-01 Symmetric resonant charge transfer cross sections between singly ionized ions and the parent atoms were measured for dysprosium and cerium in the impact energy of 200-2000eV. The cross sections were determined from the ratio between the number of ions produced by charge transfer and those in primary ion beam. The primary ion beam was produced by a laser ion source in which their atoms were ionized by laser resonant photo-ionization. The slow ions produced by charge transfer and fast primary ions were detected with Faraday cups. The obtained cross sections were (1.82{+-}0.14) x 10{sup -14} cm{sup 2} for dysprosium and (0.88{+-}0.12) x 10{sup -14} cm{sup 2} for cerium in the above energy range. The difference of these values can mostly be explained by considering the electron configurations of these atoms and ions. (author) 8. Charge transfer properties of pentacene adsorbed on silver: DFT study Energy Technology Data Exchange (ETDEWEB) N, Rekha T.; Rajkumar, Beulah J. M., E-mail: beulah-rajkumar@yahoo.co.in [PG & Research Department of Physics, Lady Doak College, Madurai 625002 (India) 2015-06-24 Charge transfer properties of pentacene adsorbed on silver is investigated using DFT methods. Optimized geometry of pentacene after adsorption on silver indicates distortion in hexagonal structure of the ring close to the silver cluster and deviations in co-planarity of carbon atoms due to the variations in bond angles and dihedral angles. Theoretically simulated absorption spectrum has a symmetric surface plasmon resonance peak around 486nm corresponding to the transfer of charge from HOMO-2 to LUMO. Theoretical SERS confirms the process of adsorption, tilted orientation of pentacene on silver surface and the charge transfers reported. Localization of electron density arising from redistribution of electrostatic potential together with a reduced bandgap of pentacene after adsorption on silver suggests its utility in the design of electro active organic semiconducting devices. 9. Charge transfer cross sections for dysprosium and cerium International Nuclear Information System (INIS) Adachi, Hajime; Tamura, Koji; Okazaki, Tetsuji; Shibata, Takemasa 1998-06-01 Symmetric resonant charge transfer cross sections between singly ionized ions and the parent atoms were measured for dysprosium and cerium in the impact energy of 200-2000eV. The cross sections were determined from the ratio between the number of ions produced by charge transfer and those in primary ion beam. The primary ion beam was produced by a laser ion source in which their atoms were ionized by laser resonant photo-ionization. The slow ions produced by charge transfer and fast primary ions were detected with Faraday cups. The obtained cross sections were (1.82±0.14) x 10 -14 cm 2 for dysprosium and (0.88±0.12) x 10 -14 cm 2 for cerium in the above energy range. The difference of these values can mostly be explained by considering the electron configurations of these atoms and ions. (author) 10. Mass and charge transfer within a floating water bridge Science.gov (United States) Fuchs, Elmar C.; Agostinho, Luewton L. F.; Eisenhut, Mathias; Woisetschläger, Jakob 2010-11-01 When high voltage is applied to pure water filled into two beakers close to each other, a connection forms spontaneously, giving the impression of a floating water bridge 1-8. This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the charge and mass transfer through the water bridge are investigated with schlieren visualization and laser interferometry. It can be shown that the addition of a pH dye increases the H+ and OH- production with subsequent electrolysis, whereas schlieren and interferometric methods reveal another mechanism where charge and mass transfer appear to be coupled. Whereas this mechanism seems to be responsible for the electrolysis-less charge and mass transfer in the water bridge, it is increasingly superseded by the electrochemical mechanism with rising conductivity. Thus it can be shown that a pH dye does only indirectly visualize the charge transfer in the water bridge since it is dragged along with the water flow like any other dye, and additionally promotes conventional electrochemical conduction mechanisms, thereby enhancing electrolysis and reducing the masscoupled charge transport and thus destabilizing the bridge. 11. Charge-transfer properties in the gas electron multiplier International Nuclear Information System (INIS) Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung 2004-01-01 The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author) 12. Scheduling of Crude Oil Operations in Refinery without Sufficient Charging Tanks Using Petri Nets Directory of Open Access Journals (Sweden) Yan An 2017-05-01 Full Text Available A short-term schedule for crude oil operations in a refinery should define and sequence the activities in detail. Each activity involves both discrete-event and continuous variables. The combinatorial nature of the scheduling problem makes it difficult to solve. For such a scheduling problem, charging tanks are a type of critical resources. If the number of charging tanks is not sufficient, the scheduling problem is further complicated. This work conducts a study on the scheduling problem of crude oil operations without sufficient charging tanks. In this case, to make a refinery able to operate, a charging tank has to be in simultaneous charging and feeding to a distiller for some time, called simultaneously-charging-and-feeding (SCF mode, leading to disturbance to the oil distillation in distillers. A hybrid Petri net model is developed to describe the behavior of the system. Then, a scheduling method is proposed to find a schedule such that the SCF mode is minimally used. It is computationally efficient. An industrial case study is given to demonstrate the obtained results. 13. Evaluation of intramolecular charge transfer state of 4-N, N ... Abstract. Intramolecular charge transfer of 4-N,N-dimethylamino cinnamaldehyde (DMACA) in vacuum and in five different aprotic solvents has been studied by using time-dependent density functional theory. (TDDFT). Polarizable continuum model (PCM) was employed to consider solvent–solute interactions. The potential ... 14. Two-Centre Close-Coupling method in charge transfer Directory of Open Access Journals (Sweden) Reza Bagheri 2017-09-01 Full Text Available In the present work, the transition matrix elements as well as differential and total scattering cross-sections for positronium formation in Positron-Hydrogen atom collision and hydrogen formation in Positronium-Hydrogen ion collision, through the charge transfer channel by Two-Centre Close-Coupling method up to a first order approximation have been calculated. The charge transfer collision is assumed to be a three-body reaction, while the projectile is a plane wave. Additionally, the hydrogen and positronium atoms are assumed, initially, to be in their ground states. For the case of charge transfer in the scattering of positron by hydrogen atoms, the differential cross sections are plotted for the energy range of 50eV to 10keV, where the Thomas peak is clearly observable. Finally, the total scattering cross-section for the charge transfer in the collision of Positron-Hydrogen and Positronium-Hydrogen ion are plotted as a function of projectile energies and compared with other methods in the literature. 15. Charge transfer in chromium-transition metal alloys International Nuclear Information System (INIS) Kulakowski, K.; Maksymowicz, A. 1984-07-01 The average T-matrix approximation is applied for calculations of charge transfer of 3d-electrons in transition metal alloys. The role of concentration, long-range and short-range atomic order is investigated. The results are in reasonable agreement with experimental data. (author) 16. Charge-Transfer Complexes Studied by Dynamic Force Spectroscopy Directory of Open Access Journals (Sweden) Jurriaan Huskens 2013-03-01 Full Text Available In this paper, the strength and kinetics of two charge-transfer complexes, naphthol-methylviologen and pyrene-methylviologen, are studied using dynamic force spectroscopy. The dissociation rates indicate an enhanced stability of the pyrene-methylviologen complex, which agrees with its higher thermodynamic stability compared to naphthol-methylviologen complex. 17. Positron Annihilation in Solid Charge-Transfer Complexes DEFF Research Database (Denmark) Lévay, B.; Jansen, P. 1979-01-01 Positron lifetime and angular correlation measurements have been carried out on 1:1 charge-transfer complexes, on their pure donor and acceptor components and on the 1:1 M mechanical mixtures of these components. Complex formation reduced the intensity of the long-lifetime component of the donor... 18. Modeling charge transfer at organic donor-acceptor semiconductor interfaces NARCIS (Netherlands) Cakir, Deniz; Bokdam, Menno; de Jong, Machiel Pieter; Fahlman, M.; Brocks, G. 2012-01-01 We develop an integer charge transfer model for the potential steps observed at interfaces between donor and acceptor molecular semiconductors. The potential step can be expressed as the difference between the Fermi energy pinning levels of electrons on the acceptor material and holes on the donor 19. Enhancing SERS by Means of Supramolecular Charge Transfer Science.gov (United States) Wong, Eric; Flood, Amar; Morales, Alfredo 2009-01-01 In a proposed method of sensing small quantities of molecules of interest, surface enhanced Raman scattering (SERS) spectroscopy would be further enhanced by means of intermolecular or supramolecular charge transfer. There is a very large potential market for sensors based on this method for rapid detection of chemical and biological hazards. In SERS, the Raman signals (vibrational spectra) of target molecules become enhanced by factors of the order of 108 when those molecules are in the vicinities of nanostructured substrate surfaces that have been engineered to have plasmon resonances that enhance local electric fields. SERS, as reported in several prior NASA Tech Briefs articles and elsewhere, has remained a research tool and has not yet been developed into a practical technique for sensing of target molecules: this is because the short range (5 to 20 nm) of the field enhancement necessitates engineering of receptor molecules to attract target molecules to the nanostructured substrate surfaces and to enable reliable identification of the target molecules in the presence of interferants. Intermolecular charge-transfer complexes have been used in fluorescence-, photoluminescence-, and electrochemistry-based techniques for sensing target molecules, but, until now, have not been considered for use in SERS-based sensing. The basic idea of the proposed method is to engineer receptor molecules that would be attached to nanostructured SERS substrates and that would interact with the target molecules to form receptor-target supramolecular charge-transfer complexes wherein the charge transfer could be photoexcited. 20. Charge transfer devices and their application in physics Energy Technology Data Exchange (ETDEWEB) Soroko, L M [Joint Inst. for Nuclear Research, Dubna (USSR) 1979-01-01 Physical properties and technical specifications of charge transfer devices (CTD) are reviewed. The CTD are semiconductor devices based on silicon single crystals. The limiting charge density of the CTD, their efficiency of charge transfer, the background noise and radiation effects are considered. Fast response and low energy consumption are characteristic features of the devices. The application of the CTD in storage devices, real time spectral data processing systems and in streamer chambers is described. The algorithms of topological transformations in the stage of scanning particle track images, which can be realized with the help of the CTD are shortly considered. It is pointed out that applications of the CTD in different fields of science and technology are numerous and expanding. 1. Theory and simulation of charge transfer through DNA - nanotube contacts International Nuclear Information System (INIS) Rink, Gunda; Kong Yong; Koslowski, Thorsten 2006-01-01 We address the problem of charge transfer between a single-stranded adenine oligomer and semiconducting boron nitride nanotubes from a theoretical and numerical perspective. The model structures have been motivated by computer simulations; sample geometries are used as the input of an electronic structure theory that is based upon an extended Su-Schrieffer-Heeger Hamiltonian. By analyzing the emerging potential energy surfaces, we obtain hole transfer rates via Marcus' theory of charge transfer. In the presence of nanotubes, these rates exceed those of isolated DNA single strands by a factor of up to 10 4 . This enhancement can be rationalized and quantified as a combination of a template effect and the participation of the tube within a superexchange mechanism 2. Active pixel sensor with intra-pixel charge transfer Science.gov (United States) Fossum, Eric R. (Inventor); Mendis, Sunetra (Inventor); Kemeny, Sabrina E. (Inventor) 2004-01-01 An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node. 3. Charge-transfer modified embedded atom method dynamic charge potential for Li-Co-O system. Science.gov (United States) Kong, Fantai; Longo, Roberto C; Liang, Chaoping; Nie, Yifan; Zheng, Yongping; Zhang, Chenxi; Cho, Kyeongjae 2017-11-29 To overcome the limitation of conventional fixed charge potential methods for the study of Li-ion battery cathode materials, a dynamic charge potential method, charge-transfer modified embedded atom method (CT-MEAM), has been developed and applied to the Li-Co-O ternary system. The accuracy of the potential has been tested and validated by reproducing a variety of structural and electrochemical properties of LiCoO 2 . A detailed analysis on the local charge distribution confirmed the capability of this potential for dynamic charge modeling. The transferability of the potential is also demonstrated by its reliability in describing Li-rich Li 2 CoO 2 and Li-deficient LiCo 2 O 4 compounds, including their phase stability, equilibrium volume, charge states and cathode voltages. These results demonstrate that the CT-MEAM dynamic charge potential could help to overcome the challenge of modeling complex ternary transition metal oxides. This work can promote molecular dynamics studies of Li ion cathode materials and other important transition metal oxides systems that involve complex electrochemical and catalytic reactions. 4. The charge transfer structure and effective energy transfer in multiplayer assembly film International Nuclear Information System (INIS) Li Mingqiang; Jian Xigao 2005-01-01 Charge transfer multiplayer films have been prepared by layer-by-layer self-assembly technique. The films incorporate the rare-earth-containing polyoxometalate K 11 [Eu{PW 11 O 39 } 2 ].nH 2 O and the rich electron polyelectrolyte poly(3-viny-1-methyl-pyridine) quaternary ammonium and display a linear increase in the absorption and film thickness with the number of deposition cycles. Ultraviolet and visible absorption spectra, atomic force micrographs, small-angle X-ray reflectivity measurements, and photoluminescence spectra were used to determine the structure of films. Linear and regular multilayer growth was observed. We can observe the formation of charge transfer complex compound in multiplayer by layer-by-layer assembly method. Most importantly, the luminescence spectra show the charge transfer band in assembly films, which suggest that energy could be effectively transferred to rare earth ions in assembly multiplayer films 5. Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma. Science.gov (United States) Yousefi, Razieh; Davis, Allen B; Carmona-Reyes, Jorge; Matthews, Lorin S; Hyde, Truell W 2014-09-01 Understanding the agglomeration of dust particles in complex plasmas requires knowledge of basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold-coated mono-disperse spherical melamine-formaldehyde monomers in a radiofrequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining three-dimensional structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, as well as the external electric field, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments. 6. Study of charge transfer reactions in a microbial fuel cell Energy Technology Data Exchange (ETDEWEB) Martin, E.; Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. de Genie Chimique; National Research Council of Canada, Montreal, PQ (Canada). Biotechnology Research Inst.; Tartakovsky, B. [National Research Council of Canada, Montreal, PQ (Canada). Biotechnology Research Inst. 2008-07-01 Electron transfer reactions in a microbial fuel cell (MFC) were evaluated. The MFC was inoculated with anaerobic mesophilic sludge and operated with carbon felt, carbon cloth, and platinum (Pt) coated carbon cloth. The MFC was then fed with either acetate or glucose as a source of fuel and operated at a temperature of 25 degrees C and a pH of 7. Scanning electron microscopy (SEM) micrographs demonstrated that the micro-organisms colonized the anodes. Cyclic voltammetry and polarization tests were conducted using different fractions of the anodophilic biofilm in order to determine charge transfer routes. The study characterized the electron transfer mechanisms used by the exoelectrogenic micro-organisms to produce electricity. It was concluded that further research is needed to characterize reaction transfer routes. 2 refs., 1 fig. 7. Charge transfer in pi-stacked systems including DNA International Nuclear Information System (INIS) Siebbeles, L.D.A. 2003-01-01 Charge migration in DNA is a subject of intense current study motivated by long-range detection of DNA damage and the potential application of DNA as a molecular wire in nanoscale electronic devices. A key structural element, which makes DNA a medium for long-range charge transfer, is the array of stacked base pairs in the interior of the double helix. The overlapping pi-orbitals of the nucleobases provide a pathway for motion of charge carriers generated on the stack. This 'pi-pathway' resembles the columnarly stacked macrocyclic cores in discotic materials such as triphenylenes. The structure of these pi-stacked systems is highly disordered with dynamic fluctuations occurring on picosecond to nanosecond time scales. Theoretical calculations, concerning the effects of structural disorder and nucleobase sequence in DNA, on the dynamics of charge carriers are presented. Electronic couplings and localization energies of charge carriers were calculated using density functional theory (DFT). Results for columnarly stacked triphenylenes and DNA nucleobases are compared. The results are used to provide insight into the factors that control the mobility of charge carriers. Further, experimental results on the site-selective oxidation of guanine nucleobases in DNA (hot spots for DNA damage) are analyzed on basis of the theoretical results 8. Charge transfer in conjugated oligomers encapsulated into carbon nanotubes Energy Technology Data Exchange (ETDEWEB) Almadori, Y.; Alvarez, L.; Michel, T.; Le Parc, R.; Bantignies, J.L.; Hermet, P.; Sauvajol, J.L. [Laboratoire Charles Coulomb UMR 5521, Universite Montpellier 2, 34095 Montpellier (France); Laboratoire Charles Coulomb UMR 5521, CNRS, 34095 Montpellier (France); Arenal, R. [Laboratoire d' Etude des Microstructures, CNRS-ONERA, 92322 Chatillon (France); Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, U. Zaragoza, 50018 Zaragoza (Spain); Babaa, R. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France); Chemical Engineering Department, University of Technology PETRONAS, UTP, Ipoh-Perak (Malaysia); Jouselme, B.; Palacin, S. [Laboratoire de Chimie des Surfaces et Interfaces, CEA, IRAMIS, SPCSI, 91191 Gif-sur-Yvette Cedex (France) 2011-11-15 This study deals with a hybrid system consisting in quaterthiophene derivative encapsulated inside single-walled and multi-walled carbon nanotubes. Investigations of the encapsulation step are performed by transmission electron microscopy. Raman spectroscopy data point out different behaviors depending on the laser excitation energy with respect to the optical absorption of quaterthiophene. At low excitation energy (far from the oligomer resonance window) there is no significant modification of the Raman spectra before and after encapsulation. By contrast, at high excitation energy (close to the oligomer resonance window), Raman spectra exhibit a G-band shift together with an important RBM intensity loss, suggesting a significant charge transfer between the inserted molecule and the host nanotubes. Those results suggest a photo induced process leading to a significant charge transfer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) 9. Barrier discharge. The transferred charge and ozone synthesis International Nuclear Information System (INIS) Gibalov, V.I.; Samoilovich, V.G. 1991-01-01 We have undertaken an experimental investigation of the influence of the conditions of barrier discharge implementation such as: the discharge gap value, the type of gas, and the polarity and dielectric permittivity of the dielectric electrode on the value of charge transferred in a micro-discharge. It is shown that the increase in the specific capacitance of the electrodes leads to proportional increase in the transferred charge value, reaching 100-200 nC in a discharge gap 1 mm, in air. In this case the amplitude and duration of a current pulse in the microdischarge reach, respectively, 10 to 15 A and 40 ns. It is also demonstrated that in air with increase in the discharge gap value one can observe a decrease in the efficiency of the ozone synthesis whereas in oxygen there exists a more complicated dependence: the maximum of efficiency is observed at a discharge gap value of 0.7 to 1.0 mm. (orig.) 10. Quasi-resonant K-K charge transfer International Nuclear Information System (INIS) Hagmann, S.; Cocke, C.L.; Richard, P.; Skutlartz, A.; Kelbch, S.; Schmidt-Boecking, H.; Schuch, R. 1983-01-01 The impact parameter dependence, P(b), of single and double K to K charge transfer have been deduced from the coincidences between K-Auger electrons and scattered particles for F 9+ + Ne and F 9+ + Ne collisions at 10 MeV and 4.4 MeV. The 4.4 MeV single K-K transfer probability exhibits oscillations with b. The P(b) for delta-electron emission is also reported. To obtain more details on the mechanism, K-Auger electron-Ne recoil ion coincidences are measured for both F 8+ and F 9+ projectiles. The relative amounts of recoil ions and of satellite and hypersatellite Auger transitions vary substantially with projectile charge state. 11 references, 11 figures 11. Transfer of momentum, mass and charge in heavy ion collisions International Nuclear Information System (INIS) Beck, F.; Feldmeier, H.; Dworzecka, M. 1979-01-01 A model for the first two phases of heavy ion collisions based on the transport of single nucleons through the window between the two scattering nuclei is described in some detail. It is pointed out that the model can account simultaneously for a large portion of the energy transfer from relative to intrinsic motion and for the observed variances in mass and charge numbers for reaction times up to the order of 10 -21 s. (P.L.) 12. Superconductivity and charge transfer excitations in high Tc superconductors International Nuclear Information System (INIS) Balseiro, C.A.; Alascio, B.; Gagliano, E.; Rojo, A. 1988-01-01 We present some numerical results to show that in a simple model which includes Cu 3d and O 2p orbitals together with inter and intra atomic correlations pairing between holes can occur due to charge transfer excitations. We present also a simple approximation to derive an effective Hamiltonian containing an interaction between particles which is attractive for some values of the different microscopic parameters 13. Momentum transfer in relativistic heavy ion charge-exchange reactions Science.gov (United States) Townsend, L. W.; Wilson, J. W.; Khan, F.; Khandelwal, G. S. 1991-01-01 Relativistic heavy ion charge-exchange reactions yield fragments (Delta-Z = + 1) whose longitudinal momentum distributions are downshifted by larger values than those associated with the remaining fragments (Delta-Z = 1, -2,...). Kinematics alone cannot account for the observed downshifts; therefore, an additional contribution from collision dynamics must be included. In this work, an optical model description of collision momentum transfer is used to estimate the additional dynamical momentum downshift. Good agreement between theoretical estimates and experimental data is obtained. 14. "Inverted" Solvent Effect on Charge Transfer in the Excited State. Science.gov (United States) Nau; Pischel 1999-10-04 Faster in cyclohexane than in acetonitrile is the fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by amines and sulfides. Although this photoreaction is induced by charge transfer (CT; see picture) and exciplexes are formed, the increase in the dipole moment of the exciplex is not large enough to offset the solvent stabilization of the excited reactants, and an "inverted" solvent effect results. 15. Interfacial Charge Transfer States in Condensed Phase Systems Science.gov (United States) Vandewal, Koen 2016-05-01 Intermolecular charge transfer (CT) states at the interface between electron-donating (D) and electron-accepting (A) materials in organic thin films are characterized by absorption and emission bands within the optical gap of the interfacing materials. CT states efficiently generate charge carriers for some D-A combinations, and others show high fluorescence quantum efficiencies. These properties are exploited in organic solar cells, photodetectors, and light-emitting diodes. This review summarizes experimental and theoretical work on the electronic structure and interfacial energy landscape at condensed matter D-A interfaces. Recent findings on photogeneration and recombination of free charge carriers via CT states are discussed, and relations between CT state properties and optoelectronic device parameters are clarified. 16. Plasma effect on tunnelling, charge transfer and transient quasimolecular states International Nuclear Information System (INIS) Fisher, D V 2003-01-01 The influence of a dense plasma environment on electron tunnelling between two ion potential wells in collectivized states and in charge-transfer collisions is studied. We show that the tunnelling probabilities in dilute plasma (in a close ion-ion collision) and in dense plasma differ strongly. The difference is due to the mixing between Stark components of donor-ion energy levels, caused by the field of spectator ions in a dense plasma. The mixing is determined by an angle α between the nearest-neighbour ion field and the total electric field acting on the donor ion. In close ion-ion binary collisions the mixing may be considered weak. However, for most plasma ions charge transfer, electron state collectivization and transient quasimolecule formation are strongly affected by the field of spectator ions. We derive approximate analytical expressions for the distribution function of α in an ideal plasma and perform molecular dynamics simulations to find the distribution function of α in both ideal and nonideal plasmas. Both α-dependent and average mixing coefficients are determined. We have found that the mixing is strong, even in ideal plasmas, and increases further with an increase in plasma nonideality. It is shown that there is no resonant charge transfer in dense plasmas. The applicability of a transient 'dicenter' quasimolecule model for dense plasmas is discussed 17. Surface Charge Transfer Doping of Monolayer Phosphorene via Molecular Adsorption. Science.gov (United States) He, Yuanyuan; Xia, Feifei; Shao, Zhibin; Zhao, Jianwei; Jie, Jiansheng 2015-12-03 Monolayer phosphorene has attracted much attention owing to its extraordinary electronic, optical, and structural properties. Rationally tuning the electrical transport characteristics of monolayer phosphorene is essential to its applications in electronic and optoelectronic devices. Herein, we study the electronic transport behaviors of monolayer phosphorene with surface charge transfer doping of electrophilic molecules, including 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), NO2, and MoO3, using density functional theory combined with the nonequilibrium Green's function formalism. F4TCNQ shows optimal performance in enhancing the p-type conductance of monolayer phosphorene. Static electronic properties indicate that the enhancement is originated from the charge transfer between adsorbed molecule and phosphorene layer. Dynamic transport behaviors demonstrate that additional channels for hole transport in host monolayer phosphorene were generated upon the adsorption of molecule. Our work unveils the great potential of surface charge transfer doping in tuning the electronic properties of monolayer phosphorene and is of significance to its application in high-performance devices. 18. Doping Phosphorene with Holes and Electrons through Molecular Charge Transfer. Science.gov (United States) Vishnoi, Pratap; Rajesh, S; Manjunatha, S; Bandyopadhyay, Arkamita; Barua, Manaswee; Pati, Swapan K; Rao, C N R 2017-11-03 An important aspect of phosphorene, the novel two-dimensional semiconductor, is whether holes and electrons can both be doped in this material. Some reports found that only electrons can be preferentially doped into phosphorene. There are some theoretical calculations showing charge-transfer interaction with both tetrathiafulvalene (TTF) and tetracyanoethylene (TCNE). We have carried out an investigation of chemical doping of phosphorene by a variety of electron donor and acceptor molecules, employing both experiment and theory, Raman scattering being a crucial aspect of the study. We find that both electron acceptors and donors interact with phosphorene by charge-transfer, with the acceptors having more marked effects. All the three Raman bands of phosphorene soften and exhibit band broadening on interaction with both donor and acceptor molecules. First-principles calculations establish the occurrence of charge-transfer between phosphorene with donors as well as acceptors. The absence of electron-hole asymmetry is noteworthy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. 19. Energy and charge transfer in ionized argon coated water clusters International Nuclear Information System (INIS) Kočišek, J.; Lengyel, J.; Fárník, M.; Slavíček, P. 2013-01-01 We investigate the electron ionization of clusters generated in mixed Ar-water expansions. The electron energy dependent ion yields reveal the neutral cluster composition and structure: water clusters fully covered with the Ar solvation shell are formed under certain expansion conditions. The argon atoms shield the embedded (H 2 O) n clusters resulting in the ionization threshold above ≈15 eV for all fragments. The argon atoms also mediate more complex reactions in the clusters: e.g., the charge transfer between Ar + and water occurs above the threshold; at higher electron energies above ∼28 eV, an excitonic transfer process between Ar + * and water opens leading to new products Ar n H + and (H 2 O) n H + . On the other hand, the excitonic transfer from the neutral Ar* state at lower energies is not observed although this resonant process was demonstrated previously in a photoionization experiment. Doubly charged fragments (H 2 O) n H 2 2+ and (H 2 O) n 2+ ions are observed and Intermolecular Coulomb decay (ICD) processes are invoked to explain their thresholds. The Coulomb explosion of the doubly charged cluster formed within the ICD process is prevented by the stabilization effect of the argon solvent 20. Efficient charge generation by relaxed charge-transfer states at organic interfaces KAUST Repository Vandewal, Koen 2013-11-17 Interfaces between organic electron-donating (D) and electron-accepting (A) materials have the ability to generate charge carriers on illumination. Efficient organic solar cells require a high yield for this process, combined with a minimum of energy losses. Here, we investigate the role of the lowest energy emissive interfacial charge-transfer state (CT1) in the charge generation process. We measure the quantum yield and the electric field dependence of charge generation on excitation of the charge-transfer (CT) state manifold via weakly allowed, low-energy optical transitions. For a wide range of photovoltaic devices based on polymer:fullerene, small-molecule:C60 and polymer:polymer blends, our study reveals that the internal quantum efficiency (IQE) is essentially independent of whether or not D, A or CT states with an energy higher than that of CT1 are excited. The best materials systems show an IQE higher than 90% without the need for excess electronic or vibrational energy. © 2014 Macmillan Publishers Limited. 1. A new technique for the study of charge transfer in multiply charged ion-ion collisions International Nuclear Information System (INIS) Shinpaugh, J.L.; Meyer, F.W.; Datz, S. 1994-01-01 While large cross sections (>10 -16 cm 2 ) have been predicted for resonant charge transfer in ion-ion collisions, no experimental data exist for multiply charged systems. A novel technique is being developed at the ORNL ECR facility to allow study of symmetric charge exchange in multiply charged ion-ion collisions using a single ion source. Specific intra-beam charge transfer collisions occurring in a well-defined interaction region labeled by negative high voltage are identified and analyzed by electrostatic analysis in combination with ion time-of-flight coincidence detection of the collision products. Center-of-mass collision energies from 400 to 1000 eV are obtained by varying source and labeling-cell voltages. In addition, by the introduction of a target gas into the high-voltage cell, this labeling-voltage method allows measurement of electron-capture and -loss cross sections for ion-atom collisions. Consequently, higher collision energies can be investigated without the requirement of placing the ECR source on a high-voltage platform 2. Efficient charge generation by relaxed charge-transfer states at organic interfaces KAUST Repository Vandewal, Koen; Albrecht, Steve N.; Hoke, Eric T.; Graham, Kenneth; Widmer, Johannes; Douglas, Jessica D.; Schubert, Marcel; Mateker, William R.; Bloking, Jason T.; Burkhard, George F.; Sellinger, Alan; Frechet, Jean; Amassian, Aram; Riede, Moritz Kilian; McGehee, Michael D.; Neher, Dieter; Salleo, Alberto 2013-01-01 Interfaces between organic electron-donating (D) and electron-accepting (A) materials have the ability to generate charge carriers on illumination. Efficient organic solar cells require a high yield for this process, combined with a minimum of energy losses. Here, we investigate the role of the lowest energy emissive interfacial charge-transfer state (CT1) in the charge generation process. We measure the quantum yield and the electric field dependence of charge generation on excitation of the charge-transfer (CT) state manifold via weakly allowed, low-energy optical transitions. For a wide range of photovoltaic devices based on polymer:fullerene, small-molecule:C60 and polymer:polymer blends, our study reveals that the internal quantum efficiency (IQE) is essentially independent of whether or not D, A or CT states with an energy higher than that of CT1 are excited. The best materials systems show an IQE higher than 90% without the need for excess electronic or vibrational energy. © 2014 Macmillan Publishers Limited. 3. Dissociative electron attachment and charge transfer in condensed matter International Nuclear Information System (INIS) Bass, A.D.; Sanche, L. 2003-01-01 Experiments using energy-selected beams of electrons incident from vacuum upon thin vapour deposited solids show that, as in the gas-phase, scattering cross sections at low energies are dominated by the formation of temporary negative ions (or resonances) and that molecular damage may be effected via dissociative electron attachment (DEA). Recent results also show that charge transfer between anionic states of target molecules and their environment is often crucial in determining cross sections for electron driven processes. Here, we review recent work from our laboratory, in which charge transfer is observed. For rare gas solids, electron exchange between the electron-exciton complex and either a metal substrate or co-adsorbed molecule enhances the desorption of metastable atoms and/or molecular dissociation. We discuss how transient electron capture by surface electron states of a substrate and subsequent electron transfer to a molecular adsorbate enhances the effective cross sections for DEA. We also consider the case of DEA to CF 2 Cl 2 condensed on water and ammonia ices, where electron exchange between pre-solvated electron states of ice and transient molecular anions can also increase DEA cross sections. Electron transfer from molecular resonances into pre-solvated electron states of ice is also discussed 4. Charge Transfer Channels in Formation of Exciplex in Polymer Blends Science.gov (United States) Dou, Fei; Zhang, Xin-Ping 2011-09-01 The strong dependence of photoluminescence of charge transfer excited states or exciplex in a blend film of poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4- phenylenediamine) (PFB) on the excitation wavelengths and morphology is investigated. The experimental results reveal that electron transfer in the LUMOs from PFB to F8BT is more efficient than hole transfer in the HOMOs from PFB to F8BT for the formation of exciplex at the interfacial junctions between these two types of molecules in the blend film. Furthermore, energy transfer from the blue-emitting PFB to the green-emitting F8BT at the interfaces introduces an additional two-step channel and thus enhances the formation of an exciplex. This is important for understanding of charge generation and separation in organic bulk heterojunctions and for design of optoelectronic devices. 5. Charge Transfer Channels in Formation of Exciplex in Polymer Blends International Nuclear Information System (INIS) Dou Fei; Zhang Xin-Ping 2011-01-01 The strong dependence of photoluminescence of charge transfer excited states or exciplex in a blend film of poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4- phenylenediamine) (PFB) on the excitation wavelengths and morphology is investigated. The experimental results reveal that electron transfer in the LUMOs from PFB to F8BT is more efficient than hole transfer in the HOMOs from PFB to F8BT for the formation of exciplex at the interfacial junctions between these two types of molecules in the blend film. Furthermore, energy transfer from the blue-emitting PFB to the green-emitting F8BT at the interfaces introduces an additional two-step channel and thus enhances the formation of an exciplex. This is important for understanding of charge generation and separation in organic bulk heterojunctions and for design of optoelectronic devices. (condensed matter: electronic structure, electrical, magnetic, and optical properties) 6. Quantum information transfer between topological and conventional charge qubits International Nuclear Information System (INIS) Li Jun; Zou Yan 2016-01-01 We propose a scheme to realize coherent quantum information transfer between topological and conventional charge qubits. We first consider a hybrid system where a quantum dot (QD) is tunnel-coupled to a semiconductor Majorana-hosted nanowire (MNW) via using gated control as a switch, the information encoded in the superposition state of electron empty and occupied state can be transferred to each other through choosing the proper interaction time to make measurements. Then we consider another system including a double QDs and a pair of parallel MNWs, it is shown that the entanglement information transfer can be realized between the two kinds of systems. We also realize long distance quantum information transfer between two quantum dots separated by an MNW, by making use of the nonlocal fermionic level formed with the pared Majorana feimions (MFs) emerging at the two ends of the MNW. Furthermore, we analyze the teleportationlike electron transfer phenomenon predicted by Tewari et al. [Phys. Rev. Lett. 100, 027001 (2008)] in our considered system. Interestingly, we find that this phenomenon exactly corresponds to the case that the information encoded in one QD just returns back to its original place during the dynamical evolution of the combined system from the perspective of quantum state transfer. (paper) 7. Charge transfer between O6+ and atomic hydrogen Science.gov (United States) Wu, Y.; Stancil, P. C.; Liebermann, H. P.; Buenker, R. J.; Schultz, D. R.; Hui, Y. 2011-05-01 The charge exchange process has been found to play a dominant role in the production of X-rays and/or EUV photons observed in cometary and planetary atmospheres and from the heliosphere. Charge transfer cross sections, especially state-selective cross sections, are necessary parameters in simulations of X-ray emission. In the present work, charge transfer due to collisions of ground state O6+(1s2 1 S) with atomic hydrogen has been investigated theoretically using the quantum-mechanical molecular-orbital close-coupling method (QMOCC). The multi-reference single- and double-excitation configuration interaction approach (MRDCI) has been applied to compute the adiabatic potential and nonadiabatic couplings, and the atomic basis sets used have been optimized with the method proposed previously to obtain precise potential data. Total and state-selective cross sections are calculated for energies between 10 meV/u and 10 keV/u. The QMOCC results are compared to available experimental and theoretical data as well as to new atomic-orbital close-coupling (AOCC) and classical trajectory Monte Carlo (CTMC) calculations. A recommended set of cross sections, based on the MOCC, AOCC, and CTMC calculations, is deduced which should aid in X-ray modeling studies. 8. Super-iron Nanoparticles with Facile Cathodic Charge Transfer Energy Technology Data Exchange (ETDEWEB) M Farmand; D Jiang; B Wang; S Ghosh; D Ramaker; S Licht 2011-12-31 Super-irons contain the + 6 valence state of iron. One advantage of this is that it provides a multiple electron opportunity to store additional battery charge. A decrease of particle size from the micrometer to the nanometer domain provides a higher surface area to volume ratio, and opportunity to facilitate charge transfer, and improve the power, voltage and depth of discharge of cathodes made from such salts. However, super-iron salts are fragile, readily reduced to the ferric state, with both heat and contact with water, and little is known of the resultant passivating and non-passivating ferric oxide products. A pathway to decrease the super-iron particle size to the nano-domain is introduced, which overcomes this fragility, and retains the battery capacity advantage of their Fe(VI) valence state. Time and power controlled mechanosynthesis, through less aggressive, dry ball milling, leads to facile charge transfer of super-iron nanoparticles. Ex-situ X-ray Absorption Spectroscopy is used to explore the oxidation state and structure of these iron oxides during discharge and shows the significant change in stability of the ferrate structure to lower oxidation state when the particle size is in the nano-domain. 9. StorNet: Integrated Dynamic Storage and Network Resource Provisioning and Management for Automated Data Transfers International Nuclear Information System (INIS) Gu Junmin; Natarajan, Vijaya; Shoshani, Arie; Sim, Alex; Katramatos, Dimitrios; Liu Xin; Yu Dantong; Bradley, Scott; McKee, Shawn 2011-01-01 StorNet is a joint project of Brookhaven National Laboratory (BNL) and Lawrence Berkeley National Laboratory (LBNL) to research, design, and develop an integrated end-to-end resource provisioning and management framework for high-performance data transfers. The StorNet framework leverages heterogeneous network protocols and storage types in a federated computing environment to provide the capability of predictable, efficient delivery of high-bandwidth data transfers for data intensive applications. The framework incorporates functional modules to perform such data transfers through storage and network bandwidth co-scheduling, storage and network resource provisioning, and performance monitoring, and is based on LBNL's BeStMan/SRM, BNL's TeraPaths, and ESNet's OSCARS systems. 10. Collective charge and mass transfer in heavy ion reactions International Nuclear Information System (INIS) Hahn, J. 1982-01-01 In this thesis the dynamics of the charge and mass asymmetry degree of freedom was studied in the framework of the fragmentation theory by means of a time-dependent Schroedinger equation. New is the introduction of a friction potential which describes the coupling of these collective degrees of freedom to the not explicitely treated other collective respectively internal degrees of freedom. Thereby it was shown that the measured widths of the isobaric charge distributions in the 86 Kr+sup(92,98)Mo reaction can be explained mainly by the quantum mechanical uncertainty in the charge asymmetry degree of freedom. The charge equilibration occurring at the begin of a deep inelastic collision can therefore by considered as a quantum mechanical, collective, damped motion which is connected with the excitation of the isovector giant dipole resonance of the nucleus-nucleus system. The study of the mass transfer in the reactions 132 Xe+ 120 Sn and 86 Kr+ 166 Er shows, how important at the begin of a deep inelastic collision shell structures and their conservation are for a large part of the reaction, even if the elemental distribution show no maxima in the region of magic shell closures. The experimental width are up to 10 MeV/A well described under conservation of the shell structure. (orig./HSI) [de 11. Charge Transfer in Collisions of S^4+ with H. Science.gov (United States) Stancil, P. C.; Turner, A. R.; Cooper, D. L.; Schultz, D. R.; Rakovic, M. J.; Fritsch, W.; Zygelman, B. 2001-05-01 Charge transfer processes due to collisions of ground state S^4+ ions with atomic hydrogen were investigated for energies between 1 meV/u and 10 MeV/u using the quantum-mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling, classical trajectory Monte Carlo (CTMC), and continuum distorted wave methods. The MOCC calculations utilized ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. A number of variants of the CTMC approach were explored, including different momentum and radial distributions for the initial state, as well as effective charge and quantum-defect models to determine the corresponding quantum state after capture into final partially-stripped S^3+ excited classical states. Hydrogen target isotope effects were explored and rate coefficients for temperatures between 100 and 10^6 K will be presented 12. Charge transfer in proton-hydrogen collisions under Debye plasma Energy Technology Data Exchange (ETDEWEB) Bhattacharya, Arka [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal (India); Kamali, M. Z. M. [Centre for Foundation Studies in Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ghoshal, Arijit, E-mail: arijit98@yahoo.com [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal (India); Department of Mathematics, Kazi Nazrul University, B.C.W. Campus, Asansol 713 304, West Bengal (India); Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ratnavelu, K. [Department of Mathematics, Kazi Nazrul University, B.C.W. Campus, Asansol 713 304, West Bengal (India) 2015-02-15 The effect of plasma environment on the 1s → nlm charge transfer, for arbitrary n, l, and m, in proton-hydrogen collisions has been investigated within the framework of a distorted wave approximation. The effect of external plasma has been incorporated using Debye screening model of the interacting charge particles. Making use of a simple variationally determined hydrogenic wave function, it has been possible to obtain the scattering amplitude in closed form. A detailed study has been made to investigate the effect of external plasma environment on the differential and total cross sections for electron capture into different angular momentum states for the incident energy in the range of 20–1000 keV. For the unscreened case, our results are in close agreement with some of the most accurate results available in the literature. 13. Polarization and charge transfer in the hydration of chloride ions International Nuclear Information System (INIS) Zhao Zhen; Rogers, David M.; Beck, Thomas L. 2010-01-01 A theoretical study of the structural and electronic properties of the chloride ion and water molecules in the first hydration shell is presented. The calculations are performed on an ensemble of configurations obtained from molecular dynamics simulations of a single chloride ion in bulk water. The simulations utilize the polarizable AMOEBA force field for trajectory generation and MP2-level calculations are performed to examine the electronic structure properties of the ions and surrounding waters in the external field of more distant waters. The ChelpG method is employed to explore the effective charges and dipoles on the chloride ions and first-shell waters. The quantum theory of atoms in molecules (QTAIM) is further utilized to examine charge transfer from the anion to surrounding water molecules. The clusters extracted from the AMOEBA simulations exhibit high probabilities of anisotropic solvation for chloride ions in bulk water. From the QTAIM analysis, 0.2 elementary charges are transferred from the ion to the first-shell water molecules. The default AMOEBA model overestimates the average dipole moment magnitude of the ion compared to the quantum mechanical value. The average magnitude of the dipole moment of the water molecules in the first shell treated at the MP2-level, with the more distant waters handled with an AMOEBA effective charge model, is 2.67 D. This value is close to the AMOEBA result for first-shell waters (2.72 D) and is slightly reduced from the bulk AMOEBA value (2.78 D). The magnitude of the dipole moment of the water molecules in the first solvation shell is most strongly affected by the local water-water interactions and hydrogen bonds with the second solvation shell, rather than by interactions with the ion. 14. Charge transfer in gold--alkali-metal systems International Nuclear Information System (INIS) Watson, R.E.; Weinert, M. 1994-01-01 Based on conventional electronegativity arguments, gold--alkali-metal compounds are expected to be among the most ''ionic'' of metallic compounds. The concepts of ionicity and charge transfer are difficult to quantify. However, the changes in bonding in the 50/50 Au--alkali-metal systems between the elemental metals and the compounds are so severe that observations can readily be made concerning their character. The results, as obtained from self-consistent electronic-structure calculations, lead to the apparently odd observation that the electron density at the alkali-metal sites in the compound increases significantly and this involves high l componennts in the charge density. This increase, however, can be attributed to Au-like orbitals spatially overlapping the alkali-metal sites. In a chemical sense, it is reasonable to consider the alkali-metal transferring charge to these Au orbitals. While normally the difference in heats of formation between muffin-tin and full-potential calculations for transition-metal--transition-metal and transition-metal--main-group (e.g., Al) compounds having high site symmetry are small, for the gold--alkali-metal systems, the changes in bonding in the compounds cause differences of ∼0.5 eV/atom between the two classes of potential. Any serious estimate of the electronic structure in these systems must account for these aspherical bonding charges. The origin of the semiconducting behavior of the heavy-alkali-metal Au compounds is shown to arise from a combination of the Au-Au separations and the ionic character of the compounds; the light-alkali-metal Au compounds, with their smaller Au-Au separations, do not have a semiconducting gap. Core-level shifts and isomer shifts are also briefly discussed 15. Quantum computing based on space states without charge transfer International Nuclear Information System (INIS) Vyurkov, V.; Filippov, S.; Gorelik, L. 2010-01-01 An implementation of a quantum computer based on space states in double quantum dots is discussed. There is no charge transfer in qubits during a calculation, therefore, uncontrolled entanglement between qubits due to long-range Coulomb interaction is suppressed. Encoding and processing of quantum information is merely performed on symmetric and antisymmetric states of the electron in double quantum dots. Other plausible sources of decoherence caused by interaction with phonons and gates could be substantially suppressed in the structure as well. We also demonstrate how all necessary quantum logic operations, initialization, writing, and read-out could be carried out in the computer. 16. Negative thermal expansion induced by intermetallic charge transfer. Science.gov (United States) Azuma, Masaki; Oka, Kengo; Nabetani, Koichiro 2015-06-01 Suppression of thermal expansion is of great importance for industry. Negative thermal expansion (NTE) materials which shrink on heating and expand on cooling are therefore attracting keen attention. Here we provide a brief overview of NTE induced by intermetallic charge transfer in A-site ordered double perovskites SaCu 3 Fe 4 O 12 and LaCu 3 Fe 4- x Mn x O 12 , as well as in Bi or Ni substituted BiNiO 3 . The last compound shows a colossal dilatometric linear thermal expansion coefficient exceeding -70 × 10 -6 K -1 near room temperature, in the temperature range which can be controlled by substitution. 17. Collisions of fast multicharged ions in gas targets: charge transfer and ionization International Nuclear Information System (INIS) Schlachter, A.S. 1981-05-01 Measurements of cross sections for charge transfer and ionization of H 2 and rare-gas targets have been made with fast, highly stripped projectiles in charge states as high as 59+. We have found an empirical scaling rule for electron-capture cross section in H 2 valid at energies above 275 keV/amu. Similar scaling might exist for other target gases. Cross sections are generally in good agreement with theory. We have found a scaling rule for electron loss from H in collisions with a fast highly stripped projectile, based on Olson's classical-trajectory Monte-Carlo calculations, and confirmed by measurements in an H 2 target. We have found a similar scaling rule for net ionization of rare-gas targets, based on Olson's CTMC calculations and the independent-electron model. Measurements are essentially consistent with the scaled cross sections. Calculations and measurements of recoil-ion charge-state spectra show large cross sections for the production of highly charged slow recoil ions 18. Charge transfer between acenes and PbS nanocrystals Energy Technology Data Exchange (ETDEWEB) Dissanayake, D M N M [Solid State Electronics Laboratory, University of Michigan, Ann Arbor, MI 48109-2122 (United States); Hatton, R A [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Lutz, T [Departments of Chemistry and Physics, Imperial College, London SW7 2AY (United Kingdom); Curry, R J; Silva, S R P [Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)], E-mail: ndissa@umich.edu 2009-05-13 Organic-inorganic hybrid heterojunctions have potential as the basis for future photovoltaic devices. Herein, we report the results of investigations exploring the possibility of using pentacene and tetracene as photoelectron donors in conjunction with PbS nanocrystals (PbS-NCs). Photoinduced charge transfer was probed using external quantum efficiency measurements on acene:PbS-NC hybrid photovoltaic devices in conjunction with photoluminescence studies of the corresponding bilayer films. It is shown that photoelectron transfer from pentacene to the PbS-NCs is inefficient as compared to that between tetracene and PbS-NCs. The latter case can be rationalized in terms of the energy level alignment at the heterojunction assuming a common vacuum level. However, in the case of pentacene:PbS-NC junctions an interfacial energy level shift must be considered in order to explain the observations. 19. Net air emissions from electric vehicles: the effect of carbon price and charging strategies. Science.gov (United States) Peterson, Scott B; Whitacre, J F; Apt, Jay 2011-03-01 Plug-in hybrid electric vehicles (PHEVs) may become part of the transportation fleet on time scales of a decade or two. We calculate the electric grid load increase and emissions due to vehicle battery charging in PJM and NYISO with the current generation mix, the current mix with a 50/tonne CO(2) price, and this case but with existing coal generators retrofitted with 80% CO(2) capture. We also examine all new generation being natural gas or wind+gas. PHEV fleet percentages between 0.4 and 50% are examined. Vehicles with small (4 kWh) and large (16 kWh) batteries are modeled with driving patterns from the National Household Transportation Survey. Three charging strategies and three scenarios for future electric generation are considered. When compared to 2020 CAFE standards, net CO(2) emissions in New York are reduced by switching from gasoline to electricity; coal-heavy PJM shows somewhat smaller benefits unless coal units are fitted with CCS or replaced with lower CO(2) generation. NO(X) is reduced in both RTOs, but there is upward pressure on SO(2) emissions or allowance prices under a cap. 20. Charge Transfer Based Colorimetric Detection of Silver Ion Energy Technology Data Exchange (ETDEWEB) Han, Seung Choul; Kim, Kwang Seob; Choi, Soon Kyu; Oh, Jinho; Lee, Jae Wook [Dong-A Univ., Busan (Korea, Republic of) 2014-05-15 We have demonstrated the colorimetric chemosensor for detection of Ag{sup +} via formation of nanoparticles which is based on the intramolecular CT interaction between the electron-rich (2,6-dialkoxynaphthalene; Np) moiety and the electron-deficient (methyl viologen; MV{sup 2+}) moiety of a single sensor molecule. Under irradiation of light, Ag{sup +} was reduced to very small silver nanoparticle by CT interaction in the presence of OEGs as flexible recognition moiety of Ag{sup +} and stabilizer for Ag nanoparticles, thus Ag nanoparticles resulted to reddish brown in the color change of sensor solution, gradually. Therefore, the charge-transfer interaction between an electron-deficient and an electron-rich units existing at a sensor molecule can be regarded as a new and efficient method to construct various colorimetric chemosensors. Donor.acceptor interactions or charge transfer (CT) interactions are an important class of non-covalent interactions and have been widely exploited in self-assembling systems. Beyond molecular chemistry, supramolecular chemistry aims at constituting highly complex, functional chemical systems from components held together by intermolecular forces. Chemosensors are the molecules of abiotic origin that bind selectively and reversibly with the analyte with concomitant change in one or more properties of the system. The recognition and signaling of ionic and neutral species of varying complexity is one of the most intensively studied areas of contemporary supramolecular chemistry. 1. Near thermal charge transfer between Ar+2 and N2 International Nuclear Information System (INIS) Holzscheiter, H.M.; Church, D.A. 1981-01-01 The near thermal charge transfer reaction of Ar +2 with N 2 has been studied at total pressures below 10 -7 Torr using a stored ion technique. Ar +2 ions produced by electron impact double ionization of Ar gas were selectively stored for times the order of seconds in a split-ring Penning-type ion trap. The decay with time of the initial ion sample number in a mixture of Ar and N 2 gases was fit to the sum of two exponentials, corresponding to different reaction rates for the 3 P and 1 D low-lying Ar +2 levels. The observed Ar +2 number decrease is attributed to the double-charge transfer process Ar +2 +N 2 →Ar+N 2 +2 →Ar+N + +N + in accord with recent flow-tube measurements. A rate constant for the metastable Ar +2 ( 1 D) level reaction with a value k( 1 D)=1.4 x 10 -9 cm 3 /sec is obtained, using the previously measured rate constant for the Ar +2 ( 3 P) state 2. Excited State Structural Dynamics of Carotenoids and Charge Transfer Systems International Nuclear Information System (INIS) Van Tassle, Aaron Justin 2006-01-01 This dissertation describes the development and implementation of a visible/near infrared pump/mid-infrared probe apparatus. Chapter 1 describes the background and motivation of investigating optically induced structural dynamics, paying specific attention to solvation and the excitation selection rules of highly symmetric molecules such as carotenoids. Chapter 2 describes the development and construction of the experimental apparatus used throughout the remainder of this dissertation. Chapter 3 will discuss the investigation of DCM, a laser dye with a fluorescence signal resulting from a charge transfer state. By studying the dynamics of DCM and of its methyl deuterated isotopomer (an otherwise identical molecule), we are able to investigate the origins of the charge transfer state and provide evidence that it is of the controversial twisted intramolecular (TICT) type. Chapter 4 introduces the use of two-photon excitation to the S1 state, combined with one-photon excitation to the S2 state of the carotenoid beta-apo-8'-carotenal. These 2 investigations show evidence for the formation of solitons, previously unobserved in molecular systems and found only in conducting polymers Chapter 5 presents an investigation of the excited state dynamics of peridinin, the carotenoid responsible for the light harvesting of dinoflagellates. This investigation allows for a more detailed understanding of the importance of structural dynamics of carotenoids in light harvesting 3. Proton-coupled electron transfer versus hydrogen atom transfer: generation of charge-localized diabatic states. Science.gov (United States) Sirjoosingh, Andrew; Hammes-Schiffer, Sharon 2011-03-24 The distinction between proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) mechanisms is important for the characterization of many chemical and biological processes. PCET and HAT mechanisms can be differentiated in terms of electronically nonadiabatic and adiabatic proton transfer, respectively. In this paper, quantitative diagnostics to evaluate the degree of electron-proton nonadiabaticity are presented. Moreover, the connection between the degree of electron-proton nonadiabaticity and the physical characteristics distinguishing PCET from HAT, namely, the extent of electronic charge redistribution, is clarified. In addition, a rigorous diabatization scheme for transforming the adiabatic electronic states into charge-localized diabatic states for PCET reactions is presented. These diabatic states are constructed to ensure that the first-order nonadiabatic couplings with respect to the one-dimensional transferring hydrogen coordinate vanish exactly. Application of these approaches to the phenoxyl-phenol and benzyl-toluene systems characterizes the former as PCET and the latter as HAT. The diabatic states generated for the phenoxyl-phenol system possess physically meaningful, localized electronic charge distributions that are relatively invariant along the hydrogen coordinate. These diabatic electronic states can be combined with the associated proton vibrational states to generate the reactant and product electron-proton vibronic states that form the basis of nonadiabatic PCET theories. Furthermore, these vibronic states and the corresponding vibronic couplings may be used to calculate rate constants and kinetic isotope effects of PCET reactions. 4. ChemNet: A Transferable and Generalizable Deep Neural Network for Small-Molecule Property Prediction Energy Technology Data Exchange (ETDEWEB) Goh, Garrett B.; Siegel, Charles M.; Vishnu, Abhinav; Hodas, Nathan O. 2017-12-08 With access to large datasets, deep neural networks through representation learning have been able to identify patterns from raw data, achieving human-level accuracy in image and speech recognition tasks. However, in chemistry, availability of large standardized and labelled datasets is scarce, and with a multitude of chemical properties of interest, chemical data is inherently small and fragmented. In this work, we explore transfer learning techniques in conjunction with the existing Chemception CNN model, to create a transferable and generalizable deep neural network for small-molecule property prediction. Our latest model, ChemNet learns in a semi-supervised manner from inexpensive labels computed from the ChEMBL database. When fine-tuned to the Tox21, HIV and FreeSolv dataset, which are 3 separate chemical tasks that ChemNet was not originally trained on, we demonstrate that ChemNet exceeds the performance of existing Chemception models, contemporary MLP models that trains on molecular fingerprints, and it matches the performance of the ConvGraph algorithm, the current state-of-the-art. Furthermore, as ChemNet has been pre-trained on a large diverse chemical database, it can be used as a universal “plug-and-play” deep neural network, which accelerates the deployment of deep neural networks for the prediction of novel small-molecule chemical properties. 5. Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface KAUST Repository Gruenewald, Marco; Schirra, Laura K.; Winget, Paul; Kozlik, Michael; Ndione, Paul F.; Sigdel, Ajaya K.; Berry, Joseph J.; Forker, Roman; Bredas, Jean-Luc; Fritz, Torsten; Monti, Oliver L. A. 2015-01-01 with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron 6. Charge transfer of O3+ ions with atomic hydrogen International Nuclear Information System (INIS) Wang, J.G.; Stancil, P.C.; Turner, A.R.; Cooper, D.L. 2003-01-01 Charge transfer processes due to collisions of ground state O 3+ (2s 2 2p 2 P) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with existing experimental and theoretical data shows our results to be in better agreement with the measurements than the previous calculations, although problems with some of the state-selective measurements are noted. Our calculations demonstrate that rotational coupling is not important for the total cross section, but for state-selective cross sections, its relevance increases with energy. For the ratios of triplet to singlet cross sections, significant departures from a statistical value are found, generally in harmony with experiment 7. Charge transfer of O3+ ions with atomic hydrogen Science.gov (United States) Wang, J. G.; Stancil, P. C.; Turner, A. R.; Cooper, D. L. 2003-01-01 Charge transfer processes due to collisions of ground state O3+(2s22p 2P) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with existing experimental and theoretical data shows our results to be in better agreement with the measurements than the previous calculations, although problems with some of the state-selective measurements are noted. Our calculations demonstrate that rotational coupling is not important for the total cross section, but for state-selective cross sections, its relevance increases with energy. For the ratios of triplet to singlet cross sections, significant departures from a statistical value are found, generally in harmony with experiment. 8. Charge Transfer in Collisions of S^4+ with He. Science.gov (United States) Wang, J. G.; Stancil, P. C.; Turner, A. R.; Cooper, D. L.; Schultz, D. R.; Rakovic, M. J.; Fritsch, W.; Zygelman, B. 2001-05-01 Charge transfer processes due to collisions of ground state S^4+ ions with atomic helium were investigated for energies between 0.1 meV/u and 10 MeV/u. Total and state-selective cross sections and rate coefficients were obtained utilizing the quantum-mechanical molecular-orbital close-coupling (MOCC), atomic-orbital close-coupling, classical trajectory Monte Carlo (CTMC), and continuum distorted wave methods. The MOCC calculations utilized ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. A number of variants of the CTMC approach were also explored. Previous data are limited to an earlier Landau-Zener calculation of the total rate coefficient for which our results are two orders of magnitude larger. An observed multichannel interference effect in the MOCC results will also be discussed. 9. Angular distribution in proton-hydrogen charge-transfer collisions International Nuclear Information System (INIS) Glembocki, O.; Halpern, A.M. 1977-01-01 Theoretical angular distributions for p-H charge transfer to the 1s state for energies of 1 keV and above have been examined and compared for three approximation schemes: the plane-wave Born approximation of Jackson and Schiff (JS), the Coulomb projected Born approximation of Geltman (G), and the distorted-wave eikonal approximation of one of the authors (D). The sharp dip in the forward distribution characteristic of JS is found to exist in G and D as well. As expected, G and D give identical results for all but the lowest energies. In the cases of G and D the dip, which is located close to that of JS, disappears and then reappears as the energy rises. Analytic high-energy limits for the angular dependence in both the JS and G cases have been found and are discussed 10. Laser-induced charge transfer in the CH6+ quasimolecule International Nuclear Information System (INIS) Errea, L.F.; Mendez, L.; Riera, A. 1985-01-01 The charge transfer cross section is calculated for C 6+ +CH(1s) collisions, through photon assisted 5gsigma--6hsigma, 5gsigma--4fsigma, 5gsigma--4fπ, and 5gsigma--4dsigma transitions. The theory developed by Copeland and Tang, and ourselves, is employed, and the validity of the approximations used is tested. The four processes considered have widely different characteristics with regards to the laser wavelength needed, the collision dynamics and the applicability of back-of-the-envelope estimates based on the Landau--Zener approximation. We point out the relevance of those processes to the impurity diagnostics of magnetically confined fusion plasmas and to the development of short wavelength lasers 11. Scaling of the helium--nitrogen charge transfer laser International Nuclear Information System (INIS) Collins, C.B.; Cunningham, A.J. 1975-01-01 The scaling to high powers of the nitrogen ion laser pumped by charge transfer from He + 2 is reported. Intense emission has been found from three laser lines at 3914, 4278, and 4709 A upon discharge of a fast-pulsed electron beam gun, APEX-1, into several atmospheres of a mixture of helium and nitrogen. Excitation current densities were 1.3 kA/cm 2 at 1 MV over a 1times10-cm transverse geometry. The efficiency of the 4278-A laser emission was found to be proportional to the total pressure raised to the 1.2 power. Outputs of 36 mJ have been obtained from the 16-cm 3 working volume at 30-atm pressure and a peak efficiency of 1.6% relative to the energy lost by the electron beam in this radiating volume has been achieved 12. Charge-transfer collisions involving few-electron systems International Nuclear Information System (INIS) Kirchner, T. 2016-01-01 Ion-atom collision systems that involve more than one electron constitute nonseparable few-body problems, whose full solution is difficult to say the least. At impact energies well below 1 keV/amu an expansion of the stationary scattering wave function in terms of a limited number of products of nuclear and molecular state wave functions (amended to satisfy scattering boundary conditions) is feasible and usually sufficient to obtain accurate charge-transfer cross sections provided the electronic wave functions include configuration interaction. At energies above 1 keV/amu this approach becomes inefficient and close-coupling methods within the semi classical approximation are better suited to treat the problem. For bare-ion collisions from helium target atoms explicit solutions of the two-electron time-dependent Schrödinger equation can be achieved, but are computationally costly and cannot be extended to problems which involve more than two electrons. 13. Positron annihilation studies of some charge transfer molecular complexes CERN Document Server El-Sayed, A; Boraei, A A A 2000-01-01 Positron annihilation lifetimes were measured for some solid charge transfer (CT) molecular complexes of quinoline compounds (2,6-dimethylquinoline, 6-methoxyquinoline, quinoline, 6-methylquinoline, 3-bromoquinoline and 2-chloro-4-methylquinoline) as electron donor and picric acid as an electron acceptor. The infrared spectra (IR) of the solid complexes clearly indicated the formation of the hydrogen-bonding CT-complexes. The annihilation spectra were analyzed into two lifetime components using PATFIT program. The values of the average and bulk lifetimes divide the complexes into two groups according to the non-bonding ionization potential of the donor (electron donating power) and the molecular weight of the complexes. Also, it is found that the ionization potential of the donors and molecular weight of the complexes have a conspicuous effect on the average and bulk lifetime values. The bulk lifetime values of the complexes are consistent with the formation of stable hydrogen-bonding CT-complexes as inferred... 14. Photoinduced Charge Transfer from Titania to Surface Doping Site. Science.gov (United States) Inerbaev, Talgat; Hoefelmeyer, James D; Kilin, Dmitri S 2013-05-16 We evaluate a theoretical model in which Ru is substituting for Ti at the (100) surface of anatase TiO 2 . Charge transfer from the photo-excited TiO 2 substrate to the catalytic site triggers the photo-catalytic event (such as water oxidation or reduction half-reaction). We perform ab-initio computational modeling of the charge transfer dynamics on the interface of TiO 2 nanorod and catalytic site. A slab of TiO 2 represents a fragment of TiO 2 nanorod in the anatase phase. Titanium to ruthenium replacement is performed in a way to match the symmetry of TiO 2 substrate. One molecular layer of adsorbed water is taken into consideration to mimic the experimental conditions. It is found that these adsorbed water molecules saturate dangling surface bonds and drastically affect the electronic properties of systems investigated. The modeling is performed by reduced density matrix method in the basis of Kohn-Sham orbitals. A nano-catalyst modeled through replacement defect contributes energy levels near the bottom of the conduction band of TiO 2 nano-structure. An exciton in the nano-rod is dissipating due to interaction with lattice vibrations, treated through non-adiabatic coupling. The electron relaxes to conduction band edge and then to the Ru cite with faster rate than hole relaxes to the Ru cite. These results are of the importance for an optimal design of nano-materials for photo-catalytic water splitting and solar energy harvesting. 15. Exciplex: An Intermolecular Charge-Transfer Approach for TADF. Science.gov (United States) Sarma, Monima; Wong, Ken-Tsung 2018-04-03 Organic materials that display thermally activated delayed fluorescence (TADF) are a striking class of functional materials that have witnessed a booming progress in recent years. In addition to pure TADF emitters achieved by the subtle manipulations of intramolecular charge transfer processes with sophisticated molecular structures, a new class of efficient TADF-based OLEDs with emitting layer formed by blending electron donor and acceptor molecules that involve intermolecular charge transfer have also been fabricated. In contrast to pure TADF materials, the exciplex-based systems can realize small ΔEST (0-0.05 eV) much more easily since the electron and hole are positioned on two different molecules, thereby giving small exchange energy. Consequently, exciplex-based OLEDs have the prospective to maximize the TADF contribution and achieve theoretical 100% internal quantum efficiency. Therefore, the challenging issue of achieving small ΔEST in organic systems could be solved. In this article, we summarize and discuss the latest and most significant developments regarding these rapidly evolving functional materials, wherein the majority of the reported exciplex forming systems are categorized into two sub-groups, viz. (a) exciplex as TADF emitters and (b) those as hosts for fluorescent, phosphorescent and TADF dopants according to their structural features and applications. The working mechanisms of the direct electroluminescence from the donor/acceptor interface and the exciplex-forming systems as co-host for the realization of high efficiency OLEDs are reviewed and discussed. This article delivers a summary of the current progresses and achievements of exciplex-based researches and points out the future challenges to trigger more research endeavors to this growing field. 16. Charge amplification and transfer processes in the gas electron multiplier International Nuclear Information System (INIS) Bachmann, S.; Bressan, A.; Ropelewski, L.; Sauli, F.; Sharma, A.; Moermann, D. 1999-01-01 We report the results of systematic investigations on the operating properties of detectors based on the gas electron multiplier (GEM). The dependence of gain and charge collection efficiency on the external fields has been studied in a range of values for the hole diameter and pitch. The collection efficiency of ionization electrons into the multiplier, after an initial increase, reaches a plateau extending to higher values of drift field the larger the GEM voltage and its optical transparency. The effective gain, fraction of electrons collected by an electrode following the multiplier, increases almost linearly with the collection field, until entering a steeper parallel plate multiplication regime. The maximum effective gain attainable increases with the reduction in the hole diameter, stabilizing to a constant value at a diameter approximately corresponding to the foil thickness. Charge transfer properties appear to depend only on ratios of fields outside and within the channels, with no interaction between the external fields. With proper design, GEM detectors can be optimized to satisfy a wide range of experimental requirements: tracking of minimum ionizing particles, good electron collection with small distortions in high magnetic fields, improved multi-track resolution and strong ion feedback suppression in large volume and time-projection chambers 17. Doping graphene films via chemically mediated charge transfer Directory of Open Access Journals (Sweden) Ishikawa Ryousuke 2011-01-01 Full Text Available Abstract Transparent conductive films (TCFs are critical components of a myriad of technologies including flat panel displays, light-emitting diodes, and solar cells. Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost. Carrier doping of graphene would potentially improve the properties of graphene-based TCFs for practical industrial applications. However, controlling the carrier type and concentration of dopants in graphene films is challenging, especially for the synthesis of p-type films. In this article, a new method for doping graphene using the conjugated organic molecule, tetracyanoquinodimethane (TCNQ, is described. Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films. Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency. Our carrier doping method based on charge transfer has a huge potential for graphene-based TCFs. 18. Classical/quantum correspondence in state selective charge transfer and excitation reactions involving highly charged ions and hydrogen International Nuclear Information System (INIS) Purkait, M 2009-01-01 State selective charge transfer and excitation cross sections for collisions of Ne q+ (q = 1-10) with atomic hydrogen are calculated within the framework of Classical Trajectory Monte Carlo (CTMC) method and Boundary Corrected Continuum Intermediate State (BCCIS) approximation. 19. Charge Transfer and Support Effects in Heterogeneous Catalysis Energy Technology Data Exchange (ETDEWEB) Hervier, Antoine [Univ. of California, Berkeley, CA (United States) 2011-12-21 The kinetic, electronic and spectroscopic properties of two-dimensional oxide-supported catalysts were investigated in order to understand the role of charge transfer in catalysis. Pt/TiO2 nanodiodes were fabricated and used as catalysts for hydrogen oxidation. During the reaction, the current through the diode, as well as its I-V curve, were monitored, while gas chromatography was used to measure the reaction rate. The current and the turnover rate were found to have the same temperature dependence, indicating that hydrogen oxidation leads to the non-adiabatic excitation of electrons in Pt. A fraction of these electrons have enough energy to ballistically transport through Pt and overcome the Schottky barrier at the interface with TiO2. The yield for this phenomenon is on the order of 10-4 electrons per product molecule formed, similar to what has been observed for CO oxidation and for the adsorption of many different molecules. The same Pt/TiO2 system was used to compare currents in hydrogen oxidation and deuterium oxidation. The current through the diode under deuterium oxidation was found to be greater than under hydrogen oxidation by a factor of three. Weighted by the difference in turnover frequencies for the two isotopes, this would imply a chemicurrent yield 5 times greater for D2 compared to H2, contrary to what is expected given the higher mass of D2. Reversible changes in the rectification factor of the diode are observed when switching between D2 and H2. These changes are a likely cause for the differences in current between the two isotopes. In the nanodiode experiments, surface chemistry leads to charge flow, suggesting the possibility of creating charge flow to tune surface chemistry. This was done first by exposing a Pt/Si diode to visible light while using it as a catalyst for H2 oxidation. Absorption of the light in the Si, combined with 20. Experimental evidence of state-selective charge transfer in inductively coupled plasma-atomic emission spectrometry International Nuclear Information System (INIS) Chan, George C.-Y.; Hieftje, Gary M. 2004-01-01 State-selective charge-transfer behavior was observed for Fe, Cr, Mn and Cu in inductively coupled plasma (ICP)-atomic emission spectrometry. Charge transfer from Ar + to Fe, Cr and Mn is state-selective because of inefficient collisional mixing of the quasiresonant charge-transfer energy levels with nearby levels. This low efficiency is the consequence of differences in electronic configuration of the core electrons. The reason for state-selective charge-transfer behavior to Cu is not clear, although a tentative explanation based on efficiency of intramultiplet and intermultiplet mixing for this special case is offered 1. Effect of Molecular Packing and Charge Delocalization on the Nonradiative Recombination of Charge-Transfer States in Organic Solar Cells KAUST Repository Chen, Xiankai 2016-09-05 In organic solar cells, a major source of energy loss is attributed to nonradiative recombination from the interfacial charge transfer states to the ground state. By taking pentacene–C60 complexes as model donor–acceptor systems, a comprehensive theoretical understanding of how molecular packing and charge delocalization impact these nonradiative recombination rates at donor–acceptor interfaces is provided. 2. Quantifying Net Synergy/Redundancy of Spontaneous Variability Regulation via Predictability and Transfer Entropy Decomposition Frameworks. Science.gov (United States) Porta, Alberto; Bari, Vlasta; De Maria, Beatrice; Takahashi, Anielle C M; Guzzetti, Stefano; Colombo, Riccardo; Catai, Aparecida M; Raimondi, Ferdinando; Faes, Luca 2017-11-01 Objective: Indexes assessing the balance between redundancy and synergy were hypothesized to be helpful in characterizing cardiovascular control from spontaneous beat-to-beat variations of heart period (HP), systolic arterial pressure (SAP), and respiration (R). Methods: Net redundancy/synergy indexes were derived according to predictability and transfer entropy decomposition strategies via a multivariate linear regression approach. Indexes were tested in two protocols inducing modifications of the cardiovascular regulation via baroreflex loading/unloading (i.e., head-down tilt at -25° and graded head-up tilt at 15°, 30°, 45°, 60°, 75°, and 90°, respectively). The net redundancy/synergy of SAP and R to HP and of HP and R to SAP were estimated over stationary sequences of 256 successive values. Results: We found that: 1) regardless of the target (i.e., HP or SAP) redundancy was prevalent over synergy and this prevalence was independent of type and magnitude of the baroreflex challenge; 2) the prevalence of redundancy disappeared when decoupling inputs from output via a surrogate approach; 3) net redundancy was under autonomic control given that it varied in proportion to the vagal withdrawal during graded head-up tilt; and 4) conclusions held regardless of the decomposition strategy. Conclusion: Net redundancy indexes can monitor changes of cardiovascular control from a perspective completely different from that provided by more traditional univariate and multivariate methods. Significance: Net redundancy measures might provide a practical tool to quantify the reservoir of effective cardiovascular regulatory mechanisms sharing causal influences over a target variable. Objective: Indexes assessing the balance between redundancy and synergy were hypothesized to be helpful in characterizing cardiovascular control from spontaneous beat-to-beat variations of heart period (HP), systolic arterial pressure (SAP), and respiration (R). Methods: Net redundancy 3. Graphene-ferromagnet interfaces: hybridization, magnetization and charge transfer. Science.gov (United States) Abtew, Tesfaye; Shih, Bi-Ching; Banerjee, Sarbajit; Zhang, Peihong 2013-03-07 Electronic and magnetic properties of graphene-ferromagnet interfaces are investigated using first-principles electronic structure methods in which a single layer graphene is adsorbed on Ni(111) and Co(111) surfaces. Due to the symmetry matching and orbital overlap, the hybridization between graphene pπ and Ni (or Co) d(z(2)) states is very strong. This pd hybridization, which is both spin and k dependent, greatly affects the electronic and magnetic properties of the interface, resulting in a significantly reduced (by about 20% for Ni and 10% for Co) local magnetic moment of the top ferromagnetic layer at the interface and an induced spin polarization on the graphene layer. The calculated induced magnetic moment on the graphene layer agrees well with a recent experiment. In addition, a substantial charge transfer across the graphene-ferromagnet interfaces is observed. We also investigate the effects of thickness of the ferromagnet slab on the calculated electronic and magnetic properties of the interface. The strength of the pd hybridization and the thickness-dependent interfacial properties may be exploited to design structures with desirable magnetic and transport properties for spintronic applications. 4. Versatile charge transfer through anthraquinone films for electrochemical sensing applications International Nuclear Information System (INIS) Venarusso, Luna B.; Tammeveski, Kaido; Maia, Gilberto 2011-01-01 Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to study the effect of anthraquinone (AQ) films on the charge transfer rate of β-nicotinamide adenine dinucleotide (NAD + ), dopamine (DA), and ferricyanide on glassy carbon (GC) electrodes in solutions of different pH. Maximum blocking action on the Fe(CN) 6 3- redox probe was observed at pH 7 and open-circuit potential (OCP). However, maximum electron hopping effect was observed at pH 9 at both -0.58 V and -0.85 V for Fe(CN) 6 3- , pH 7 at -0.58 V for NAD + , and pH 9 at -0.58 V for DA, suggesting that electron hopping in AQ films on a GC surface is dependent on both pH and electrode potential. These findings lend support for the application of these films in the detection of soluble redox probes such as NAD + and DA at biological pH values (from 7 to 9). 5. Low-energy charge transfer excitations in NiO International Nuclear Information System (INIS) Sokolov, V I; Yermakov, A Ye; Uimin, M A; Gruzdev, N B; Pustovarov, V A; Churmanov, V N; Ivanov, V Yu; Sokolov, P S; Baranov, A N; Moskvin, A S 2012-01-01 Comparative analysis of photoluminescence (PL) and photoluminescence excitation (PLE) spectra of NiO poly- and nanocrystals in the spectral range 2-5.5 eV reveals two PLE bands peaked near 3.7 and 4.6 eV with a dramatic rise in the low-temperature PLE spectral weight of the 3.7 eV PLE band in the nanocrystalline NiO as compared with its polycrystalline counterpart. In frames of a cluster model approach we assign the 3.7 eV PLE band to the low-energy bulk-forbidden p-d (t 1g (π)-e g ) charge transfer (CT) transition which becomes the allowed one in the nanocrystalline state while the 4.6 eV PLE band is related to a bulk allowed d-d (e g -e g ) CT transition scarcely susceptible to the nanocrystallization. The PLE spectroscopy of the nanocrystalline materials appears to be a novel informative technique for inspection of different CT transitions. 6. Vibrational spectra of charge transfer complexes of lead phthalocyanine International Nuclear Information System (INIS) Oza, A.T.; Patel, S.G.; Patel, R.G.; Prajapati, S.M.; Vaidya, Rajiv 2005-01-01 Infrared spectra of six charge transfer complexes of lead phthalocyanine (PbPc), namely, PbPc-I 2 , PbPc-TCNQ, PbPc-DDQ, PbPc-chloranil, PbPc-TCNE and PbPc-TNF, where TCNQ=7,7,8,8-tetracyano-1,4-quinodimethane, DDQ=2,3-dichloro-5,6-dicyano-p-benzoquinone, TCNE=tetracyano-p-ethylene and TNF=2,4,5,7-tetranitro-9-fluorenone have been studied in the range of 400-4000 cm -1 . The analysis of featureless absorption is carried out for studying transition across the Peierls gap of 0.225 eV. The electronic absorption envelopes at 1500, 1100 and 3400 cm -1 are found to have Gaussian shapes and not the degenerate oscillators, as found in purely organic conductors. There is a pairing of two electrons on phthalocyanine ligand as required in Little's model, and consequently, the electronic absorption envelope is a doublet. Electronic absorption envelope is a doublet showing two peaks at 1500 and 1100 cm -1 , indicating a two-electron problem in PbPc. Metal-ligand vibrations between 400 and 700 cm -1 lead to indirect transition between the valence and conduction bands and phonon-mediated coupling between metal chains and the side chains 7. Versatile charge transfer through anthraquinone films for electrochemical sensing applications Energy Technology Data Exchange (ETDEWEB) Venarusso, Luna B. [Department of Chemistry, Universidade Federal de Mato Grosso do Sul, Caixa Postal 549, Campo Grande, MS 79070-900 (Brazil); Tammeveski, Kaido [Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu (Estonia); Maia, Gilberto, E-mail: gilberto.maia@ufms.br [Department of Chemistry, Universidade Federal de Mato Grosso do Sul, Caixa Postal 549, Campo Grande, MS 79070-900 (Brazil) 2011-10-01 Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to study the effect of anthraquinone (AQ) films on the charge transfer rate of {beta}-nicotinamide adenine dinucleotide (NAD{sup +}), dopamine (DA), and ferricyanide on glassy carbon (GC) electrodes in solutions of different pH. Maximum blocking action on the Fe(CN){sub 6}{sup 3-} redox probe was observed at pH 7 and open-circuit potential (OCP). However, maximum electron hopping effect was observed at pH 9 at both -0.58 V and -0.85 V for Fe(CN){sub 6}{sup 3-}, pH 7 at -0.58 V for NAD{sup +}, and pH 9 at -0.58 V for DA, suggesting that electron hopping in AQ films on a GC surface is dependent on both pH and electrode potential. These findings lend support for the application of these films in the detection of soluble redox probes such as NAD{sup +} and DA at biological pH values (from 7 to 9). 8. Magnetically coupled resonance wireless charging technology principles and transfer mechanisms Science.gov (United States) Zhou, Jiehua; Wan, Jian; Ma, Yinping 2017-05-01 With the tenure of Electric-Vehicle rising around the world, the charging methods have been paid more and more attention, the current charging mode mainly has the charging posts and battery swapping station. The construction of the charging pile or battery swapping station not only require lots of manpower, material costs but the bare conductor is also easy to generate electric spark hidden safety problems, still occupies large space. Compared with the wired charging, wireless charging mode is flexible, unlimited space and location factors and charging for vehicle safety and quickly. It complements the traditional charging methods in adaptability and the independent charge deficiencies. So the researching the wireless charging system have an important practical significance and application value. In this paper, wireless charging system designed is divided into three parts: the primary side, secondary side and resonant coupling. The main function of the primary side is to generate high-frequency alternating current, so selecting CLASS-E amplifier inverter structure through the research on full bridge, half-bridge and power amplification circuit. Addition, the wireless charging system is susceptible to outside interference, frequency drift phenomenon. Combined with the wireless energy transmission characteristics, resonant parts adopt resonant coupling energy transmission scheme and the Series-Series coupling compensation structure. For the electric vehicle charging power and voltage requirements, the main circuit is a full bridge inverter and Boost circuit used as the secondary side. 9. Analysis of matters associated with the transferring of object-oriented applications to platform .Net using C# programming language Science.gov (United States) Sarsimbayeva, S. M.; Kospanova, K. K. 2015-11-01 The article provides the discussion of matters associated with the problems of transferring of object-oriented Windows applications from C++ programming language to .Net platform using C# programming language. C++ has always been considered to be the best language for the software development, but the implicit mistakes that come along with the tool may lead to infinite memory leaks and other errors. The platform .Net and the C#, made by Microsoft, are the solutions to the issues mentioned above. The world economy and production are highly demanding applications developed by C++, but the new language with its stability and transferability to .Net will bring many advantages. An example can be presented using the applications that imitate the work of queuing systems. Authors solved the problem of transferring of an application, imitating seaport works, from C++ to the platform .Net using C# in the scope of Visual Studio. 10. Charge-transfer cross sections in collisions of ground-state Ca and H+ Science.gov (United States) Dutta, C. M.; Oubre, C.; Nordlander, P.; Kimura, M.; Dalgarno, A. 2006-03-01 We have investigated collisions of Ca(4s2) with H+ in the energy range of 200eV/u-10keV/u using the semiclassical molecular-orbital close-coupling (MOCC) method with 18 coupled molecular states ( 11Σ+1 and seven Π+1 states) to determine charge-transfer cross sections. Except for the incoming channel 6Σ+1 , the molecular states all correspond to charge-transfer channels. Inclusion of Ca2+-H- is crucial in the configuration-interaction calculation for generating the molecular wave functions and potentials. Because of the Coulomb attraction, the state separating to Ca2+-H- creates many avoided crossings, even though at infinite separation it lies energetically above all other states that we included. Because of the avoided crossings between the incoming channel 6Σ+1 and the energetically close charge-transfer channel 7Σ+1 the charge-transfer interaction occurs at long range. This makes calculations of charge-transfer cross sections by the MOCC method very challenging. The total charge-transfer cross sections increase monotonically from 3.4×10-15cm2 at 200eV/u to 4.5×10-15cm2 at 10keV/u . Charge transfer occurs mostly to the excited Ca+(5p) state in the entire energy range, which is the sum of the charge transfer to 7Σ+1 and 4Π+1 . It accounts for ˜47% of the total charge transfer cross sections at 200eV/u . However, as the energy increases, transfer to Ca+(4d) increases, and at 10keV/u the charge-transfer cross sections for Ca+(5p) and Ca+(4d) become comparable, each giving ˜38% of the total cross section. 11. Charge-transfer cross sections in collisions of ground-state Ca and H+ International Nuclear Information System (INIS) Dutta, C. M.; Oubre, C.; Nordlander, P.; Kimura, M.; Dalgarno, A. 2006-01-01 We have investigated collisions of Ca(4s 2 ) with H + in the energy range of 200 eV/u-10 keV/u using the semiclassical molecular-orbital close-coupling (MOCC) method with 18 coupled molecular states (11 1 Σ + and seven 1 Π + states) to determine charge-transfer cross sections. Except for the incoming channel 6 1 Σ + , the molecular states all correspond to charge-transfer channels. Inclusion of Ca 2+ -H - is crucial in the configuration-interaction calculation for generating the molecular wave functions and potentials. Because of the Coulomb attraction, the state separating to Ca 2+ -H - creates many avoided crossings, even though at infinite separation it lies energetically above all other states that we included. Because of the avoided crossings between the incoming channel 6 1 Σ + and the energetically close charge-transfer channel 7 1 Σ + the charge-transfer interaction occurs at long range. This makes calculations of charge-transfer cross sections by the MOCC method very challenging. The total charge-transfer cross sections increase monotonically from 3.4x10 -15 cm 2 at 200 eV/u to 4.5x10 -15 cm 2 at 10 keV/u. Charge transfer occurs mostly to the excited Ca + (5p) state in the entire energy range, which is the sum of the charge transfer to 7 1 Σ + and 4 1 Π + . It accounts for ∼47% of the total charge transfer cross sections at 200 eV/u. However, as the energy increases, transfer to Ca + (4d) increases, and at 10 keV/u the charge-transfer cross sections for Ca + (5p) and Ca + (4d) become comparable, each giving ∼38% of the total cross section 12. Correlation between charge transfer and exchange coupling in carbon-based magnetic materials Energy Technology Data Exchange (ETDEWEB) Nguyen, Anh Tuan, E-mail: tuanna@hus.edu.vn [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Science and Technology Department, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan); Nguyen, Van Thanh; Nguyen, Huy Sinh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Pham, Thi Tuan Anh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, College of Hai Duong, Nguyen Thi Due, Hai Duong (Viet Nam); Do, Viet Thang [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, Haiphong University, 171 Phan Dang Luu, Kien An, Hai Phong (Viet Nam); Dam, Hieu Chi [Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan) 2015-10-15 Several forms of carbon-based magnetic materials, i.e. single radicals, radical dimers, and alternating stacks of radicals and diamagnetic molecules, have been investigated using density-functional theory with dispersion correction and full geometry optimization. Our calculated results demonstrate that the C{sub 31}H{sub 15} (R{sub 4}) radical has a spin of ½. However, in its [R{sub 4}]{sub 2} dimer structure, the net spin becomes zero due to antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, eight alternating stacks, R{sub 4}/D{sub 2m}/R{sub 4} (with m = 3-10), were designed. Our calculated results show that charge transfer (Δn) between R{sub 4} radicals and the diamagnetic molecule D{sub 2m} occurs with a mechanism of spin exchange (J) in stacks. The more electrons that transfer from R{sub 4} to D{sub 2m}, the stronger the ferromagnetic spin-exchange in stacks. In addition, our calculated results show that Δn can be tailored by adjusting the electron affinity (E{sub a}) of D{sub 2m}. The correlation between Δn, E{sub a}, m, and J is discussed. These results give some hints for the design of new ferromagnetic carbon-based materials. 13. About application of the 'rough' net method for decision of the neutron transfer transient equation International Nuclear Information System (INIS) Seleznev, E.F.; Tarasenko, V.V. 1995-01-01 Method of the decision of a transient equation of the neutrons transfer is developed, which at preservation of necessary accuracy permits considerably to speed up a finding of the decision up to modeling of processes in reactor in real time. The transient equation of neutrons transfer in one-group diffusion approximation is decided by the finite-difference method. The calculating model of reactor is divided into rather large zones, where the currents on internal borders are away, and on external borders ones are a sum of currents on the borders of small-sized zones. For the decision of an equation in finite-difference kind the numerical scheme 'Time - integrate' is used, which permits to search the decision in a half-explicit kind with rather large temporary step. The decision for density of neutrons flux is determine by the SOR method. Under the conducted preliminary analysis of an algorithm efficiency it is possible to conclude, that the time of the decision on a computer can be reduced in 3 and more times, in depending on 'roughness' of a calculated net in comparison with computation on a complete net. The realized algorithm can be used as for scientific researches, and as neutron-physical block of the simulator. 6 refs., 1 fig 14. Charge transfer and ionization occurring in proton- and helium ion-atom collisions International Nuclear Information System (INIS) DuBois, R.D. 1985-12-01 Two examples are presented where specific channels have been identified that are responsible for single and double target ionization via direct coulomb ionization or charge transfer processes. Using ratios of absolute cross sections that have been measured for these processes it was shown that an independent electron model should be appropriate for calculating direct double target ionization but generally appears to be inadequate in calculating charge transfer plus ionization and double charge transfer cross sections. At present such detailed information can be obtained only in limited cases. However cross sections with detailed final charge state information should provide stringent tests for present and future theoretical work. 22 refs., 2 figs 15. ARCHITECTURE OF A CHARGE-TRANSFER STATE REGULATING LIGHT HARVESTING IN A PLANT ANTENNA PROTEIN Energy Technology Data Exchange (ETDEWEB) Fleming, Graham; Ahn, Tae Kyu; Avenson, Thomas J.; Ballottari, Matteo; Cheng, Yuan-Chung; Niyogi, Krishna K.; Bassi, Roberto; Fleming, Graham R. 2008-04-02 Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge-transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). In this work, we present evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a de-localized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can `tune? the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophylls-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE. 16. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules Energy Technology Data Exchange (ETDEWEB) Morherr, Antonia, E-mail: morherr@stud.uni-frankfurt.de [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Witt, Sebastian [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Chernenkaya, Alisa [Graduate School Materials Science in Mainz, 55128 Mainz (Germany); Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bäcker, Jan-Peter [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Schönhense, Gerd [Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bolte, Michael [Institut für anorganische Chemie, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Krellner, Cornelius [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany) 2016-09-01 New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F{sub x}, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules. 17. Dynamical interaction of He atoms with metal surfaces: Charge transfer processes International Nuclear Information System (INIS) Flores, F.; Garcia Vidal, F.J.; Monreal, R. 1993-01-01 A self-consistent Kohn-Sham LCAO method is presented to calculate the charge transfer processes between a He * -atom and metal surfaces. Intra-atomic correlation effects are taken into account by considering independently each single He-orbital and by combining the different charge transfer processes into a set of dynamical rate equations for the different ion charge fractions. Our discussion reproduces qualitatively the experimental evidence and gives strong support to the method presented here. (author). 24 refs, 4 figs 18. Dynamics of the excited state intramolecular charge transfer International Nuclear Information System (INIS) Joo, T.; Kim, C.H. 2006-01-01 The 6-dodecanoyl-2-dimethylaminonaphtalene (laurdan), a derivative of 6-propanoyl- 2-dimethylaminonaphthalene (prodan), has been used as a fluorescent probe in cell imaging, especially in visualizing the lipid rafts by the generalized polarization (GP) images, where GP=(I 440 -I 490 )/(I 440 +I 490 ) with I being the fluorescence intensity. The fluorescence spectrum of laurdan is sensitive to its dipolar environment due to the intramolecular charge transfer (ICT) process in S 1 state, which results in a dual emission from the locally excited (LE) and the ICT states. The ICT process and the solvation of the ICT state are very sensitive to the dipolar nature of the environment. In this work, the ICT of laurdan in ethanol has been studied by femtosecond time resolved fluorescence (TRF), especially TRF spectra measurement without the conventional spectral reconstruction method. TRF probes the excited states exclusively, a unique advantage over the pump/probe transient absorption technique, although time resolution of the TRF is generally lower than transient absorption and the TRF spectra measurement was possible only though the spectral reconstruction. Over the years, critical advances in TRF technique have been made in our group to achieve <50 fs time resolution with direct full spectra measurement capability. Detailed ICT and the subsequent solvation processes can be visualized unambiguously from the TRF spectra. Fig. 1 shows the TRF spectra of laurdan in ethanol at several time delays. Surprisingly, two bands at 433 and 476 nm are clearly visible in the TRF spectra of laurdan even at T = 0 fs. As time increases, the band at 476 nm shifts to the red while its intensity increases. The band at 433 nm also shifts slightly to the red, but loses intensity as time increases. The intensity of the 476 nm band reaches maximum at around 5 ps, where it is roughly twice as intense as that at 0 fs, and stays constant until lifetime decay is noticeable. The spectra were fit by 19. Charge-transfer interactions of Cr species with DNA. Science.gov (United States) Nowicka, Anna M; Matysiak-Brynda, Edyta; Hepel, Maria 2017-10-01 Interactions of Cr species with nucleic acids in living organisms depend strongly on Cr oxidation state and the environmental conditions. As the effects of these interactions range from benign to pre-mutagenic to carcinogenic, careful assessment of the hazard they pose to human health is necessary. We have investigated methods that would enable quantifying the DNA damage caused by Cr species under varying environmental conditions, including UV, O 2 , and redox potential, using simple instrumental techniques which could be in future combined into a field-deployable instrumentation. We have employed electrochemical quartz crystal nanogravimetry (EQCN), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) to evaluate the extent of DNA damage expressed in terms of guanine oxidation yield (η) and changes in specific characteristics provided by these techniques. The effects of the interactions of Cr species with DNA were analyzed using a model calf thymus DNA (ctDNA) film on a gold electrode (Au@ctDNA) in different media, including: (i) Cr(VI), (ii) Cr(VI) reduced at -0.2V, (iii) Cr(III)+UV radiation+O 2 , and Cr(III), obtaining the η values: 7.4±1.4, 1.5±0.4, 1.1±0.31%, and 0%, respectively, thus quantifying the hazard posed. The EIS measurements have enabled utilizing the decrease in charge-transfer resistance (R ct ) for ferri/ferrocyanide redox probe at an Au@ctDNA electrode to assess the oxidative ctDNA damage by Cr(VI) species. In this case, circular dichroism indicates an extensive damage to the ctDNA hydrogen bonding. On the other hand, Cr(III) species have not induced any damage to ctDNA, although the EQCN measurements show an electrostatic binding to DNA. Copyright © 2017 Elsevier Inc. All rights reserved. 20. Charged-particle transfer reactions and nuclear astrophysics problems International Nuclear Information System (INIS) Artemov, S.V.; Yarmukhamedov, R.; Yuldashev, B.S.; Burtebaev, N.; Duysebaev, A.; Kadyrzhanov, K.K. 2002-01-01 In the report a review of the recent results of calculation of the astrophysical S-factors S(E) for the D(α, γ) 6 Li, 3 He(α, γ) 7 Be, 7 Be(p, γ) 8 Be, 12,13 C(p, γ) 13, 14 N and 12 C(p,γ) 16 O* reactions at extremely low energies E, including value E=0 , performed within the framework of a new method taking into account the additional information about the nuclear vertex constant (Nc) (or the respective asymptotic normalization coefficient) are presented. The required values of Nc can be obtained from an analysis of measured differential cross-sections of proton and α-particle transfer reactions (for example A( 3 He,d)B, 6 Li(d, 6 Li)d, 6 Li(α, 6 Li)α, 12 C( 6 Li, d) 16 O* etc.). A comparative analysis between the results obtained by different authors is also done. Taking into account an important role of the NVC's values for the nuclear astrophysical A(p, γ)B and A(α, γ)B reactions, a possibility of obtaining the reliable NVC values for the virtual decay B→A+p and B→A+α from the analysis of differential cross sections both sub- and above-barrier A( 3 He, d) and A( 6,7 Li, 2,3 H)B reactions is discussed in detail. In this line the use the isochronous cyclotron U-150 M, the 'DC-60' heavy ion machine and electrostatic charge-exchanging accelerator UKP-2-1 of Institute of Nuclear Physics of National Nuclear Center of the Republic of Kazakhstan for carrying out the needed experiments is considered and the possibility of the obtained data application for the astrophysical interest is also discussed 1. Self-interaction and charge transfer in organic semiconductors Energy Technology Data Exchange (ETDEWEB) Koerzdoerfer, Thomas 2009-12-18 This work concentrates on the problem of self-interaction, which is one of the most serious problems of commonly used approximative density functionals. As a major result of this work, it is demonstrated that self-interaction plays a decisive role for the performance of different approximative functionals in predicting accurate electronic properties of organic molecular semiconductors. In search for a solution to the self-interaction problem, a new concept for correcting commonly used density functionals for self-interaction is introduced and applied to a variety of systems, spanning small molecules, extended molecular chains, and organic molecular semiconductors. It is further shown that the performance of functionals that are not free from self-interaction can vary strongly for different systems and observables of interest, thus entailing the danger of misinterpretation of the results obtained from those functionals. The underlying reasons for the varying performance of commonly used density functionals are discussed thoroughly in this work. Finally, this thesis provides strategies that allow to analyze the reliability of commonly used approximations to the exchange-correlation functional for particular systems of interest. This cumulative dissertation is divided into three parts. Part I gives a short introduction into DFT and its time-dependent extension (TDDFT). Part II provides further insights into the self-interaction problem, presents a newly developed concept for the correction of self-interaction, gives an introduction into the publications, and discusses their basic results. Finally, the four publications on self-interaction and charge-transfer in extended molecular systems and organic molecular semiconductors are collected in Part III. (orig.) 2. Receptor-Mediated Melanoma Targeting with Radiolabeled α-Melanocyte-Stimulating Hormone: Relevance of the Net Charge of the Ligand Directory of Open Access Journals (Sweden) Alex N. Eberle 2017-04-01 Full Text Available A majority of melanotic and amelanotic melanomas overexpress melanocortin type 1 receptors (MC1Rs for α-melanocyte-stimulating hormone. Radiolabeled linear or cyclic analogs of α-MSH have a great potential as diagnostic or therapeutic tools for the management of malignant melanoma. Compounds such as [111In]DOTA-NAP-amide exhibit high affinity for the MC1R in vitro, good tumor uptake in vivo, but they may suffer from relatively high kidney uptake and retention in vivo. We have shown previously that the introduction of negative charges into radiolabeled DOTA-NAP-amide peptide analogs may enhance their excretion and reduce kidney retention. To address the question of where to place negative charges within the ligand, we have extended these studies by designing two novel peptides, Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys(DOTA-d-Asp-d-Asp-OH (DOTA-NAP-d-Asp-d-Asp with three negative charges at the C-terminal end (overall net charge of the molecule −2 and DOTA-Gly-Tyr(P-Nle-Asp-His-d-Phe-Arg-Trp-NH2 (DOTA-Phospho-MSH2-9 with two negative charges in the N-terminal region (net charge −1. The former peptide showed markedly reduced receptor affinity and biological activity by >10-fold compared to DOTA-NAP-amide as reference compound, and the latter peptide displayed similar bioactivity and receptor affinity as the reference compound. The uptake by melanoma tumor tissue of [111In]DOTA-Phospho-MSH2-9 was 7.33 ± 0.47 %ID/g 4 h after injection, i.e., almost equally high as with [111In]DOTA-NAP-amide. The kidney retention was 2.68 ± 0.18 %ID/g 4 h after injection and hence 44% lower than that of [111In]DOTA-NAP-amide. Over an observation period from 4 to 48 h, the tumor-to-kidney ratio of [111In]DOTA-Phospho-MSH2-9 was 35% more favorable than that of the reference compound. In a comparison of DOTA-NAP-d-Asp-d-Asp, DOTA-Phospho-MSH2-9 and DOTA-NAP-amide with five previously published analogs of DOTA-NAP-amide that altogether cover a range 3. Voltammetry for the charge transfer at two immiscible electrolyte solutions interface International Nuclear Information System (INIS) Kihara, S.; Suzuki, M.; Maeda, K.; Ogura, K.; Matsui, M.; Yoshida, Z. 1989-01-01 The voltammetry for the charge transfer (VCT) at the interface of immicible solutions is a very powerful method for understanding the dynamic features of the charge transfer because of its unmatched advantage that the transfer energy and the number of charges transferred can be measured simultaneously and in situ. In the present paper, several novel systems for electron transfer are outlined, and the following topics are discussed based on results obtained by the current scan polarography at the solution dropping electrode developed as a technique for VCT: the relation between the half-wave potential in VCT for ion transfer and the characteristics of the ion transferred; the relation between the half-wave potential in VCT for electron transfer and the electrochemical nature of a redox couple added in water and that added in organic solution; and the ion transfer through a liquid membrane promoted by electron transfer. Observations are presented and discussion is made on the characteristics of ion transfer polarograms, those of electron transfer polarograms, and ion transfer promoted by electron transfer at a liquid/membrane interface. (N.K.) 4. Design of a Software for Calculating Isoelectric Point of a Polypeptide According to Their Net Charge Using the Graphical Programming Language LabVIEW Science.gov (United States) Tovar, Glomen 2018-01-01 A software to calculate the net charge and to predict the isoelectric point (pI) of a polypeptide is developed in this work using the graphical programming language LabVIEW. Through this instrument the net charges of the ionizable residues of the chains of the proteins are calculated at different pH values, tabulated, pI is predicted and an Excel… 5. Cost-Effectiveness Comparison of Coupler Designs of Wireless Power Transfer for Electric Vehicle Dynamic Charging Directory of Open Access Journals (Sweden) Weitong Chen 2016-11-01 Full Text Available This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT, meant for electric vehicle (EV dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance of horizontal offset, and flux density. Then, the optimal cost-effectiveness combination is selected for EV dynamic charging. The corresponding performances of the proposed charging system are compared and analyzed by both simulation and experimentation. The results verify the validity of the proposed dynamic charging system for EVs. 6. Reduced Charge Transfer Exciton Recombination in Organic Semiconductor Heterojunctions by Molecular Doping Science.gov (United States) Deschler, Felix; da Como, Enrico; Limmer, Thomas; Tautz, Raphael; Godde, Tillmann; Bayer, Manfred; von Hauff, Elizabeth; Yilmaz, Seyfullah; Allard, Sybille; Scherf, Ullrich; Feldmann, Jochen 2011-09-01 We investigate the effect of molecular doping on the recombination of electrons and holes localized at conjugated-polymer-fullerene interfaces. We demonstrate that a low concentration of p-type dopant molecules (<4% weight) reduces the interfacial recombination via charge transfer excitons and results in a favored formation of separated carriers. This is observed by the ultrafast quenching of photoluminescence from charge transfer excitons and the increase in photoinduced polaron density by ˜70%. The results are consistent with a reduced formation of emissive charge transfer excitons, induced by state filling of tail states. 7. Robust Stacking-Independent Ultrafast Charge Transfer in MoS2/WS2 Bilayers. Science.gov (United States) Ji, Ziheng; Hong, Hao; Zhang, Jin; Zhang, Qi; Huang, Wei; Cao, Ting; Qiao, Ruixi; Liu, Can; Liang, Jing; Jin, Chuanhong; Jiao, Liying; Shi, Kebin; Meng, Sheng; Liu, Kaihui 2017-12-26 Van der Waals-coupled two-dimensional (2D) heterostructures have attracted great attention recently due to their high potential in the next-generation photodetectors and solar cells. The understanding of charge-transfer process between adjacent atomic layers is the key to design optimal devices as it directly determines the fundamental response speed and photon-electron conversion efficiency. However, general belief and theoretical studies have shown that the charge transfer behavior depends sensitively on interlayer configurations, which is difficult to control accurately, bringing great uncertainties in device designing. Here we investigate the ultrafast dynamics of interlayer charge transfer in a prototype heterostructure, the MoS 2 /WS 2 bilayer with various stacking configurations, by optical two-color ultrafast pump-probe spectroscopy. Surprisingly, we found that the charge transfer is robust against varying interlayer twist angles and interlayer coupling strength, in time scale of ∼90 fs. Our observation, together with atomic-resolved transmission electron characterization and time-dependent density functional theory simulations, reveals that the robust ultrafast charge transfer is attributed to the heterogeneous interlayer stretching/sliding, which provides additional channels for efficient charge transfer previously unknown. Our results elucidate the origin of transfer rate robustness against interlayer stacking configurations in optical devices based on 2D heterostructures, facilitating their applications in ultrafast and high-efficient optoelectronic and photovoltaic devices in the near future. 8. Charge separation in photoinitiated electron transfer reactions induced by a polyelectrolyte International Nuclear Information System (INIS) Meyerstein, D.; Rabani, J.; Matheson, M.S.; Meisel, D. 1978-01-01 When uncharged molecules quench the luminescence of Ru(bpy) 3 /sup 2+/ by electron transfer to the quencher, the addition of poly(vinyl sulfate) (PVS) may, through its potential field, affect the rate of quenching, enhance the net separated charge yield, and slow the back reaction of the separated photoredox products. In all such cases that we have studied the quenching rate in the presence of PVS was reduced to about 60% of the rate measured in the absence of PVS. For two neutral species, iron(III) nitrilotriacetate (FeNTA) and cobalt(III) acetylacetonate (Co(acac) 3 ), photoreduction of the quencher was observed, and the redox yield escaping geminate recombination was substantially increased by added PVS. In the case of FeNTA the rate of the bulk back reaction was not changed appreciably by the presence of PVS owing to the rapid neutralization of Fe(NTA) - by protonation. For Co(acac) 3 the rate of the bulk back reaction was decreased by several orders of magnitude and the back reaction was shown to occur via the enolate form of the ligand which is released to the bulk solution. 4 figures, 4 tables 9. b-Cyclodextrin-assisted intervalence charge transfer in mixed- valent Indian Academy of Sciences (India) Administrator The study of intramolecular electron transfer in redox active binuclear transition metal complexes is of great fundamental importance and is an area of contemporary research interest. Though there are many reports on the role of bridging ligands (BL) in tuning metal–metal interactions and intramolecular electron transfers in ... 10. Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping KAUST Repository Begum, Raihana; Parida, Manas R.; Abdelhady, Ahmed L.; Banavoth, Murali; AlYami, Noktan; Ahmed, Ghada H.; Hedhili, Mohamed N.; Bakr, Osman; Mohammed, Omar F. 2016-01-01 Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT 11. Multiple nucleon transfer in damped nuclear collisions. [Lectures, mass charge, and linear and angular momentum transport Energy Technology Data Exchange (ETDEWEB) Randrup, J. 1979-07-01 This lecture discusses a theory for the transport of mass, charge, linear, and angular momentum and energy in damped nuclear collisions, as induced by multiple transfer of individual nucleons. 11 references. 12. Positronium Inhibition and Quenching by Organic Electron Acceptors and Charge Transfer Complexes DEFF Research Database (Denmark) Jansen, P.; Eldrup, Morten Mostgaard; Jensen, Bror Skytte 1975-01-01 Positron lifetime measurements were performed on a series of organic electron acceptors and charge-transfer complexes in solution. The acceptors cause both positronium (Ps) inhibition (with maybe one exception) and quenching, but when an acceptor takes part in a charge-transfer complex...... in terms of the spur reaction model of Ps formation. Correlation was also made to gas phase reaction between electron acceptors and free electron, as well as to pulse radiolysis data.... 13. Synthesis and photophysical properties of a novel terephthalic PH sensor based on internal charge transfer International Nuclear Information System (INIS) Miladinova, Polya M. 2016-01-01 A novel fluorescence sensing derivative of 2-aminodimethylterephthalate configured as a “fluorophore-receptor” system was synthesized and investigated. Due to the internal charge transfer, the designed fluorophore was able to act as a pH-probe via an “off-on” fluorescence sensing mechanism. The sensor activity toward protons as cations and hydroxide as anions in DMF was studied by monitoring the changes of the fluorescence intensity. Keywords: 2-aminoterephthalic derivative, ICT (internal charge transfer), pH sensor. 14. High Pressure Optical Studies of the Thallous Halides and of Charge-Transfer Complexes Science.gov (United States) Jurgensen, Charles Willard High pressure was used to study the insulator -to-metal transition in sulfur and the thallous halides and to study the intermolecular interactions in charge -transfer complexes. The approach to the band overlap insulator -to-metal transition was studied in three thallous halides and sulfur by optical absorption measurements of the band gap as a function of pressure. The band gap of sulfur continuously decreases with pressure up to the insulator -to-metal transition which occurs between 450 and 485 kbars. The results on the thallous halides indicate that the indirect gap decreases more rapidly than the direct gap; the closing of the indirect gap is responsible for the observed insulator -to-metal transitions. High pressure electronic and vibrational spectroscopic measurements on the solid-state complexes of HMB-TCNE were used to study the intermolecular interactions of charge -transfer complexes. The vibrational frequency shifts indicate that the degree of charge transfer increases with pressure which is independently confirmed by an increase in the molar absorptivity of the electronic charge-transfer peak. Induction and dispersion forces contribute towards a red shift of the charge-transfer peak; however, charge-transfer resonance contributes toward a blue shift and this effect is dominant for the HMB-TCNE complexes. High pressure electronic spectra were used to study the effect of intermolecular interactions on the electronic states of TCNQ and its complexes. The red shifts with pressure of the electronic spectra of TCNQ and (TCNQ)(' -) in polymer media and of crystalline TCNQ can be understood in terms of Van der Waals interactions. None of the calculations which considered intradimer distance obtained the proper behavior for either the charge-transfer of the locally excited states of the complexes. The qualitative behavior of both states can be interpreted as the effect of increased mixing of the locally excited and charge transfer states. 15. The influence of electric charge transferred during electro-mechanical reshaping on mechanical behavior of cartilage Science.gov (United States) Protsenko, Dimitry E.; Lim, Amanda; Wu, Edward C.; Manuel, Cyrus; Wong, Brian J. F. 2011-03-01 Electromechanical reshaping (EMR) of cartilage has been suggested as an alternative to the classical surgical techniques of modifying the shape of facial cartilages. The method is based on exposure of mechanically deformed cartilaginous tissue to a low level electric field. Electro-chemical reactions within the tissue lead to reduction of internal stress, and establishment of a new equilibrium shape. The same reactions offset the electric charge balance between collagen and proteoglycan matrix and interstitial fluid responsible for maintenance of cartilage mechanical properties. The objective of this study was to investigate correlation between the electric charge transferred during EMR and equilibrium elastic modulus. We used a finite element model based on the triphasic theory of cartilage mechanical properties to study how electric charges transferred in the electro-chemical reactions in cartilage can change its mechanical responses to step displacements in unconfined compression. The concentrations of the ions, the strain field and the fluid and ion velocities within the specimen subject to an applied mechanical deformation were estimated and apparent elastic modulus (the ratio of the equilibrium axial stress to the axial strain) was calculated as a function of transferred charge. The results from numerical calculations showed that the apparent elastic modulus decreases with increase in electric charge transfer. To compare numerical model with experimental observation we measured elastic modulus of cartilage as a function of electric charge transferred in electric circuit during EMR. Good correlation between experimental and theoretical data suggests that electric charge disbalance is responsible for alteration of cartilage mechanical properties. 16. Proton transfer to charged platinum electrodes. A molecular dynamics trajectory study. Science.gov (United States) Wilhelm, Florian; Schmickler, Wolfgang; Spohr, Eckhard 2010-05-05 A recently developed empirical valence bond (EVB) model for proton transfer on Pt(111) electrodes (Wilhelm et al 2008 J. Phys. Chem. C 112 10814) has been applied in molecular dynamics (MD) simulations of a water film in contact with a charged Pt surface. A total of seven negative surface charge densities σ between -7.5 and -18.9 µC cm(-2) were investigated. For each value of σ, between 30 and 84 initial conditions of a solvated proton within a water slab were sampled, and the trajectories were integrated until discharge of a proton occurred on the charged surfaces. We have calculated the mean rates for discharge and for adsorption of solvated protons within the adsorbed water layer in contact with the metal electrode as a function of surface charge density. For the less negative values of σ we observe a Tafel-like exponential increase of discharge rate with decreasing σ. At the more negative values this exponential increase levels off and the discharge process is apparently transport limited. Mechanistically, the Tafel regime corresponds to a stepwise proton transfer: first, a proton is transferred from the bulk into the contact water layer, which is followed by transfer of a proton to the charged surface and concomitant discharge. At the more negative surface charge densities the proton transfer into the contact water layer and the transfer of another proton to the surface and its discharge occur almost simultaneously. 17. Electron transfer and decay processes of highly charged iodine ions International Nuclear Information System (INIS) Sakaue, Hiroyuki A.; Danjo, Atsunori; Hosaka, Kazumoto 2005-01-01 In the present experimental work we have investigated multi-electron transfer processes in I q+ (q=10, 15, 20 and 25) + Ne, Ar, Kr and Xe collisions at 1.5q keV energy. The branching ratios between Auger and radiative decay channels have been measured in decay processes of multiply excited states formed by multi-electron transfer collisions. It has been shown that, in all the multi-electron transfer processes investigated, the Auger decays are far dominant over the radiative decay processes and the branching ratios are clearly characterized by the average principal quantum number of the initial excited states of projectile ions. We could express the branching ratios in high Rydberg states formed in multi-electron transfer processes by using the decay probability of one Auger electron emission. (author) 18. CNDO/SCF molecular orbital structural studies and charge transfer ... African Journals Online (AJOL) dimethoxy- diquinone (DQ) has been discussed and compared with some related compounds. The electron transfer between DQ and uracil was studied in ethanol as an interaction medium. The ionization potentials and the electron affinities of the ... 19. High Power Wireless Transfer : For Charging High Power Batteries OpenAIRE Gill, Himmat 2017-01-01 Wireless power transfer (WPT) is developing with emerging of new technologies that has made it possible to transfer electricity over certain distances without any physical contact, offering significant benefits to modern automation systems, medical applications, consumer electronic, and especially in electric vehicle systems. The goal of this study is to provide a brief review of existing compensation topologies for the loosely coupled transformer. The technique used to simulate a co... 20. Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory. Science.gov (United States) Isegawa, Miho; Gao, Jiali; Truhlar, Donald G 2011-08-28 Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi-Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi-Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred. © 2011 American Institute of Physics 1. Charge transfer in DNA: role of base pairing Czech Academy of Sciences Publication Activity Database Kratochvílová, Irena; Bunček, M.; Schneider, Bohdan 2009-01-01 Roč. 38, Suppl. (2009), S123-S123 ISSN 0175-7571. [EBSA European Biophysics Congress /7./. Genoa, 11.07.2009-15.07.2009] Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z50520701 Keywords : DNA charge transport * base pairing Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.437, year: 2009 2. Identification of the Heat Transfer Coefficient at the Charge Surface Heated on the Chamber Furnace Directory of Open Access Journals (Sweden) Gołdasz A. 2017-06-01 Full Text Available The inverse method was applied to determine the heat flux reaching the charge surface. The inverse solution was based upon finding the minimum of the error norm between the measured and calculated temperatures. The charge temperature field was calculated with the finite element method by solving the heat transfer equation for a square charge made of 15HM steel heated on all its surfaces. On the basis of the mean value of heat flux, the value of the heat transfer coefficient at each surface was determined depending on the surface temperature of the material heated. 3. Charge transfer and bond lengths in YBa2Cu3-xMxO6+y International Nuclear Information System (INIS) Jorgensen, J.D.; Rhyne, J.J.; Neumann, D.A.; Miceli, P.F.; Tarascon, J.M.; Greene, L.H.; Barboux, P. 1989-01-01 We discuss the effects of doping on the Cu chain sites in YBa 2 Cu 3-x M x O 6+y . The relationship between bond lengths obtained from neutron scattering and charge transfer is evaluated in terms of bond valence. In particular, it is concluded that removing an oxygen from the chains transfers one electron to the planes. 24 refs., 3 figs 4. Using metal complex-labeled peptides for charge transfer-based biosensing with semiconductor quantum dots Science.gov (United States) Medintz, Igor L.; Pons, Thomas; Trammell, Scott A.; Blanco-Canosa, Juan B.; Dawson, Philip E.; Mattoussi, Hedi 2009-02-01 Luminescent colloidal semiconductor quantum dots (QDs) have unique optical and photonic properties and are highly sensitive to charge transfer in their surrounding environment. In this study we used synthetic peptides as physical bridges between CdSe-ZnS core-shell QDs and some of the most common redox-active metal complexes to understand the charge transfer interactions between the metal complexes and QDs. We found that QD emission underwent quenching that was highly dependent on the choice of metal complex used. We also found that quenching traces the valence or number of metal complexes brought into close proximity of the nanocrystal surface. Monitoring of the QD absorption bleaching in the presence of the metal complex provided insight into the charge transfer mechanism. The data suggest that two distinct charge transfer mechanisms can take place. One directly to the QD core states for neutral capping ligands and a second to surface states for negatively charged capping ligands. A basic understanding of the proximity driven charge-transfer and quenching interactions allowed us to construct proteolytic enzyme sensing assemblies with the QD-peptide-metal complex conjugates. 5. Effects of system net charge and electrostatic truncation on all-atom constant pH molecular dynamics † Science.gov (United States) Chen, Wei; Shen, Jana K. 2014-01-01 Constant pH molecular dynamics offers a means to rigorously study the effects of solution pH on dynamical processes. Here we address two critical questions arising from the most recent developments of the all-atom continuous constant pH molecular dynamics (CpHMD) method: 1) What is the effect of spatial electrostatic truncation on the sampling of protonation states? 2) Is the enforcement of electrical neutrality necessary for constant pH simulations? We first examined how the generalized reaction field and force shifting schemes modify the electrostatic forces on the titration coordinates. Free energy simulations of model compounds were then carried out to delineate the errors in the deprotonation free energy and salt-bridge stability due to electrostatic truncation and system net charge. Finally, CpHMD titration of a mini-protein HP36 was used to understand the manifestation of the two types of errors in the calculated pK a values. The major finding is that enforcing charge neutrality under all pH conditions and at all time via co-titrating ions significantly improves the accuracy of protonation-state sampling. We suggest that such finding is also relevant for simulations with particle-mesh Ewald, considering the known artifacts due to charge-compensating background plasma. PMID:25142416 6. Effects of system net charge and electrostatic truncation on all-atom constant pH molecular dynamics. Science.gov (United States) Chen, Wei; Shen, Jana K 2014-10-15 Constant pH molecular dynamics offers a means to rigorously study the effects of solution pH on dynamical processes. Here, we address two critical questions arising from the most recent developments of the all-atom continuous constant pH molecular dynamics (CpHMD) method: (1) What is the effect of spatial electrostatic truncation on the sampling of protonation states? (2) Is the enforcement of electrical neutrality necessary for constant pH simulations? We first examined how the generalized reaction field and force-shifting schemes modify the electrostatic forces on the titration coordinates. Free energy simulations of model compounds were then carried out to delineate the errors in the deprotonation free energy and salt-bridge stability due to electrostatic truncation and system net charge. Finally, CpHMD titration of a mini-protein HP36 was used to understand the manifestation of the two types of errors in the calculated pK(a) values. The major finding is that enforcing charge neutrality under all pH conditions and at all time via cotitrating ions significantly improves the accuracy of protonation-state sampling. We suggest that such finding is also relevant for simulations with particle mesh Ewald, considering the known artifacts due to charge-compensating background plasma. Copyright © 2014 Wiley Periodicals, Inc. 7. Integer Charge Transfer and Hybridization at an Organic Semiconductor/Conductive Oxide Interface KAUST Repository Gruenewald, Marco 2015-02-11 We investigate the prototypical hybrid interface formed between PTCDA and conductive n-doped ZnO films by means of complementary optical and electronic spectroscopic techniques. We demonstrate that shallow donors in the vicinity of the ZnO surface cause an integer charge transfer to PTCDA, which is clearly restricted to the first monolayer. By means of DFT calculations, we show that the experimental signatures of the anionic PTCDA species can be understood in terms of strong hybridization with localized states (the shallow donors) in the substrate and charge back-donation, resulting in an effectively integer charge transfer across the interface. Charge transfer is thus not merely a question of locating the Fermi level above the PTCDA electron-transport level but requires rather an atomistic understanding of the interfacial interactions. The study reveals that defect sites and dopants can have a significant influence on the specifics of interfacial coupling and thus on carrier injection or extraction. 8. Photoinduced partial charge transfer between conjugated polymer and fullerene in solutions International Nuclear Information System (INIS) Lin Hongzhen; Weng Yufeng; Huang Hongmin; He Qingguo; Zheng Min; Bai Fenglian 2004-01-01 Photoinduced charge transfer between a conjugated polymer and C 60 and the related processes were investigated in dilute solutions. The substantial fluorescence quenching is correlated with the efficient exciton diffusion within the polymer chains, according to which a sphere-of-action mechanism is proposed. An emissive exciplex was found formed between the conjugated polymer and fullerene in a nonpolar solvent, indicating the occurrence of a photoinduced partial charge transfer process. The low-energy sites in the polymer are believed to play a crucial role in the partial charge transfer. The asymmetry of the exciplex provides a method for evaluating the tendency of photoinduced charge separation between the donor and the acceptor. This method allows screening candidates for photovoltaic applications 9. Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey Science.gov (United States) Madenjian, Charles P.; David, Solomon R.; Rediske, Richard R.; O’Keefe, James P. 2012-01-01 Lake trout (Salvelinus namaycush) were fed bloater (Coregonus hoyi) in eight laboratory tanks over a 135-d experiment. At the start of the experiment, four to nine fish in each tank were sacrificed, and the concentrations of 75 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 10 lake trout remaining in each of the eight tanks at the end of the experiment as well as in the bloater fed to the lake trout. Each lake trout was weighed at the start and the end of the experiment, and the amount of food eaten by the lake trout was recorded. Using these measurements, net trophic transfer efficiency (γ) from the bloater to the lake trout in each of the eight tanks was calculated for each of the 75 congeners. Results showed that γ did not vary significantly with the degree of chlorination of the PCB congeners, and γ averaged 0.66 across all congeners. However,γ did show a slight, but significant, decrease as logKOW increased from 6.0 to 8.2. Activity level of the lake trout did not have a significant effect on γ. 10. Photophysics of charge transfer in a polyfluorene/violanthrone blend Science.gov (United States) Cabanillas-Gonzalez, J.; Virgili, T.; Lanzani, G.; Yeates, S.; Ariu, M.; Nelson, J.; Bradley, D. D. C. 2005-01-01 We present a study of the photophysical and photovoltaic properties of blends of violanthrone in poly[9, 9-bis (2-ethylhexyl)-fluorene-2, 7-diyl ] (PF2/6) . Photoluminescence quenching and photocurrent measurements show moderate efficiencies for charge generation, characteristic of such polymer/dye blends. Pump-probe measurements on blend films suggest that while ˜47% of the total exciton population dissociates within 4ps of photoexcitation, only ˜32% subsequently results in the formation of dye anions. We attribute the discrepancy to the likely formation of complex species with long lifetimes, such as stabilized interface charge pairs or exciplexes. This conclusion is supported by the appearance of a long lifetime component of 2.4ns in the dynamics of the photoinduced absorption signal associated to polarons in photoinduced absorption bands centered at 560nm . 11. An abnormally slow proton transfer reaction in a simple HBO derivative due to ultrafast intramolecular-charge transfer events. Science.gov (United States) Alarcos, Noemí; Gutierrez, Mario; Liras, Marta; Sánchez, Félix; Douhal, Abderrazzak 2015-07-07 We report on the steady-state, picosecond and femtosecond time-resolved studies of a charge and proton transfer dye 6-amino-2-(2'-hydroxyphenyl)benzoxazole (6A-HBO) and its methylated derivative 6-amino-2-(2'-methoxyphenyl)benzoxazole (6A-MBO), in different solvents. With femtosecond resolution and comparison with the photobehaviour of 6A-MBO, we demonstrate for 6A-HBO in solution, the photoproduction of an intramolecular charge-transfer (ICT) process at S1 taking place in ∼140 fs or shorter, followed by solvent relaxation in the charge transferred species. The generated structure (syn-enol charge transfer conformer) experiences an excited-state intramolecular proton-transfer (ESIPT) reaction to produce a keto-type tautomer. This subsequent proton motion occurs in 1.2 ps (n-heptane), 14 ps (DCM) and 35 ps (MeOH). In MeOH, it is assisted by the solvent molecules and occurs through tunneling for which we got a large kinetic isotope effect (KIE) of about 13. For the 6A-DBO (deuterated sample in CD3OD) the global proton-transfer reaction takes place in 200 ps, showing a remarkable slow KIE regime. The slow ESIPT reaction in DCM (14 ps), not through tunnelling as it is not sensitive to OH/OD exchange, has however to overcome an energy barrier using intramolecular as well as solvent coordinates. The rich ESIPT dynamics of 6A-HBO in the used solutions is governed by an ICT reaction, triggered by the amino group, and it is solvent dependent. Thus, the charge injection to a 6A-HBO molecular frame makes the ICT species more stable, and the phenol group less acidic, slowing down the subsequent ESIPT reaction. Our findings bring new insights into the coupling between ICT and ESIPT reactions on the potential-energy surfaces of several barriers. 12. Impact of fuel-dependent electricity retail charges on the value of net-metered PV applications in vertically integrated systems International Nuclear Information System (INIS) Nikolaidis, Alexandros I.; Milidonis, Andreas; Charalambous, Charalambos A. 2015-01-01 Retail electricity charges inevitably influence the financial rationale of using net-metered photovoltaic (PV) applications since their structure as well as their level may vary significantly over the life-cycle of a customer-sited PV generation system. This subsequently introduces a further uncertainty for a ratepayer considering a net-metered PV investment. To thoroughly comprehend this uncertainty, the paper employs a top-down approach – in vertically integrated environments – to model the volatility of partially hedged electricity charges and its subsequent impact on the value of bill savings from net-metered PV systems. Besides the utility's pricing strategy and rate structures, particular emphasis is given in modeling the fossil fuel mix component that introduces a significant source of uncertainty on electricity charges and thus on the value of bill savings of net-metered, customer-sited, PV applications. - Highlights: • A top-down approach of developing traditional electricity charges is provided. • The combined effect of pricing strategies, rate structures and fuels is examined. • Fossil fuel prices can substantially affect the net metering compensation. • A financial risk assessment for net-metered PV systems is performed 13. Complexes with charge transfer and ion-radical salts in catalysis Energy Technology Data Exchange (ETDEWEB) Krylov, O V [AN SSSR, Moscow. Inst. Khimicheskoj Fiziki 1978-01-01 Considered are the data experimentally proving formation of complexes with charge transfer as intermediate complexes in homogeneous and heterogeneous catalysis. Catalytic activity correlations with charge transfer energy (and in heterogeneous catalysis with width of semiconductor forbidden band can be useful while selection of catalysts (MoO/sub 3//MgO; V/sub 2/O/sub 5//MgO; MoO/sub 3//Al/sub 2/O/sub 3/; V/sub 2/O/sub 5//Al/sub 2/O/sub 3/). A review of papers on catalytic activity of the previously prepared complexes with charge transfer and ion-radical salts is given. The use of alkali metal complexes with aromatic compounds showed their high activity in hydrogenation reactions and proved principle possibility of activation of hydrogen and hydrocarbons by the systems which do not contain transfer metals. 14. Estimating Net Primary Productivity Beneath Snowpack Using Snowpack Radiative Transfer Modeling and Global Satellite Data Science.gov (United States) Barber, D. E.; Peterson, M. C. 2002-05-01 Sufficient photosynthetically active radiation (PAR) penetrates snow for plants to grow beneath snowpack during late winter or early spring in tundra ecosystems. During the spring in this ecosystem, the snowpack creates an environment with higher humidity and less variable and milder temperatures than on the snow-free land. Under these conditions, the amount of PAR available is likely to be the limiting factor for plant growth. Current methods for determining net primary productivity (NPP) of tundra ecosystems do not account for this plant growth beneath snowpack, apparently resulting in underestimating plant production there. We are currently in the process of estimating the magnitude of this early growth beneath snow for tundra ecosystems. Our method includes a radiative transfer model that simulates diffuse and direct PAR penetrating snowpack based on downwelling PAR values and snow depth data from global satellite databases. These PAR levels are convolved with plant growth for vegetation that thrives beneath snowpacks, such as lichen. We expect to present the net primary production for Cladonia species (a common Arctic lichen) that has the capability of photosynthesizing at low temperatures beneath snowpack. This method may also be used to study photosynthesis beneath snowpacks in other hardy plants. Lichens are used here as they are common in snow-covered regions, flourish under snowpack, and provide an important food source for tundra herbivores (e.g. caribou). In addition, lichens are common in arctic-alpine environments and our results can be applied to these ecosystems as well. Finally, the NPP of lichen beneath snowpack is relatively well understood compared to other plants, making it ideal vegetation for this first effort at estimating the potential importance of photosynthesis at large scales. We are examining other candidate plants for their photosynthetic potential beneath snowpack at this time; however, little research has been done on this topic. We 15. 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Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Szymanski, Maciej; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tarazona Martinez, Alfonso; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; Øvrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Weber, Michael; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym 2013-04-10 We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at$\\sqrt{s_{NN}}$= 2.76 TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudo-rapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the ALICE data points are between the theoretically predicted values for a hadron gas and a Quark-Gluon Plasma. 16. A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots Energy Technology Data Exchange (ETDEWEB) Kortschot, R. J.; Bakelaar, I. A.; Erné, B. H.; Kuipers, B. W. M., E-mail: B.W.M.Kuipers@uu.nl [Van ' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands) 2014-03-15 A sensitive dielectric spectroscopy setup is built to measure the response of nanoparticles dispersed in a liquid to an alternating electric field over a frequency range from 10{sup −2} to 10{sup 7} Hz. The measured complex permittivity spectrum records both the rotational dynamics due to a permanent electric dipole moment and the translational dynamics due to net charges. The setup consists of a half-transparent capacitor connected in a bridge circuit, which is balanced on pure solvent only, using a software-controlled compensating voltage. In this way, the measured signal is dominated by the contributions of the nanoparticles rather than by the solvent. We demonstrate the performance of the setup with measurements on a dispersion of colloidal CdSe quantum dots in the apolar liquid decalin. 17. A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots. Science.gov (United States) Kortschot, R J; Bakelaar, I A; Erné, B H; Kuipers, B W M 2014-03-01 A sensitive dielectric spectroscopy setup is built to measure the response of nanoparticles dispersed in a liquid to an alternating electric field over a frequency range from 10(-2) to 10(7) Hz. The measured complex permittivity spectrum records both the rotational dynamics due to a permanent electric dipole moment and the translational dynamics due to net charges. The setup consists of a half-transparent capacitor connected in a bridge circuit, which is balanced on pure solvent only, using a software-controlled compensating voltage. In this way, the measured signal is dominated by the contributions of the nanoparticles rather than by the solvent. We demonstrate the performance of the setup with measurements on a dispersion of colloidal CdSe quantum dots in the apolar liquid decalin. 18. Charge Transfer Properties Through Graphene Layers in Gas Detectors CERN Document Server Thuiner, P.; Jackman, R.B.; Müller, H.; Nguyen, T.T.; Oliveri, E.; Pfeiffer, D.; Resnati, F.; Ropelewski, L.; Smith, J.A.; van Stenis, M.; Veenhof, R. 2016-01-01 Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical, electrical and optical properties. For the first time graphene layers suspended on copper meshes were installed into a gas detector equipped with a gaseous electron multiplier. Measurements of low energy electron and ion transfer through graphene were conducted. In this paper we describe the sample preparation for suspended graphene layers, the testing procedures and we discuss the preliminary results followed by a prospect of further applications. 19. Experimental determination of net protein charge and A(tot) and K(a) of nonvolatile buffers in canine plasma. Science.gov (United States) Constable, Peter D; Stämpfli, Henry R 2005-01-01 Acid-base abnormalities frequently are present in sick dogs. The mechanism for an acid-base disturbance can be determined with the simplified strong ion approach, which requires accurate values for the total concentration of plasma nonvolatile buffers (A(tot)) and the effective dissociation constant for plasma weak acids (K(a)). The aims of this study were to experimentally determine A(tot) and K(a) values for canine plasma. Plasma was harvested from 10 healthy dogs; the concentrations of quantitatively important strong ions (Na+, K+, Ca2+, Mg2+, Cl-, L-lactate) and nonvolatile buffer ions (total protein, albumin, phosphate) were determined; and the plasma was tonometered with CO2 at 37 degrees C. Strong ion difference (SID) was calculated from the measured strong ion concentrations, and nonlinear regression was used to estimate values for A(tot) and K(a), which were validated with data from an in vitro and in vivo study. Mean (+/- SD) values for canine plasma were A(tot) = (17.4 +/- 8.6) mM (equivalent to 0.273 mmol/g of total protein or 0.469 mmol/g of albumin); K(a) = (0.17 +/- 0.11) x 10(-7); pK(a) = 7.77. The calculated SID for normal canine plasma (pH = 7.40; P(CO2) = 37 mm Hg; [total protein] = 64 g/L) was 27 mEq/L. The net protein charge for normal canine plasma was 0.25 mEq/g of total protein or 0.42 mEq/g of albumin. Application of the experimentally determined values for A(tot), K(a), and net protein charge should improve understanding of the mechanism for complex acid-base disturbances in dogs. 20. Experimental determination of net protein charge and A(tot) and K(a) of nonvolatile buffers in human plasma. Science.gov (United States) Staempfli, Henry R; Constable, Peter D 2003-08-01 The mechanism for an acid-base disturbance can be determined by using the strong ion approach, which requires species-specific values for the total concentration of plasma nonvolatile buffers (Atot) and the effective dissociation constant for plasma weak acids (Ka). The aim of this study was to experimentally determine Atot and Ka values for human plasma by using in vitro CO2 tonometry. Plasma Pco2 was systematically varied from 25 to 145 Torr at 37 degrees C, thereby altering plasma pH over the physiological range of 6.90-7.55, and plasma pH, Pco2, and concentrations of quantitatively important strong ions (Na+, K+, Ca2+, Mg2+, Cl-, lactate) and buffer ions (total protein, albumin, phosphate) were measured. Strong ion difference was estimated, and nonlinear regression was used to calculate Atot and Ka from the measured pH and Pco2 and estimated strong ion difference; the Atot and Ka values were then validated by using a published data set (Figge J, Rossing TH, and Fencl V, J Lab Clin Med 117: 453-467, 1991). The values (mean +/- SD) were as follows: Atot = 17.2 +/- 3.5 mmol/l (equivalent to 0.224 mmol/g of protein or 0.378 mmol/g of albumin); Ka = 0.80 +/- 0.60 x 10-7; negative log of Ka = 7.10. Mean estimates were obtained for strong ion difference (37 meq/l) and net protein charge (13+.0 meq/l). The experimentally determined values for Atot, Ka, and net protein charge should facilitate the diagnosis and treatment of acid-base disturbances in critically ill humans. 1. Experimental determination of net protein charge, [A]tot, and Ka of nonvolatile buffers in bird plasma. Science.gov (United States) Stämpfli, Henry; Taylor, Michael; McNicoll, Carl; Gancz, Ady Y; Constable, Peter D 2006-06-01 The quantitative mechanistic acid-base approach to clinical assessment of acid-base status requires species-specific values for [A]tot (the total concentration of nonvolatile buffers in plasma) and Ka (the effective dissociation constant for weak acids in plasma). The aim of this study was to determine [A]tot and Ka values for plasma in domestic pigeons. Plasma from 12 healthy commercial domestic pigeons was tonometered with 20% CO2 at 37 degrees C. Plasma pH, Pco2, and plasma concentrations of strong cations (Na, K, Ca), strong anions (Cl, L-lactate), and nonvolatile buffer ions (total protein, albumin, phosphate) were measured over a pH range of 6.8-7.7. Strong ion difference (SID) (SID5=Na+K+Ca-Cl-lactate) was used to calculate [A]tot and Ka from the measured pH and Pco2 and SID5. Mean (+/-SD) values for bird plasma were as follows: [A]tot=7.76+/-2.15 mmol/l (equivalent to 0.32 mmol/g of total protein, 0.51 mmol/g of albumin, 0.23 mmol/g of total solids); Ka=2.15+/-1.15x10(-7); and pKa=6.67. The net protein charge at normal pH (7.43) was estimated to be 6 meq/l; this value indicates that pigeon plasma has a much lower anion gap value than mammals after adjusting for high mean L-lactate concentrations induced by restraint during blood sampling. This finding indicates that plasma proteins in pigeons have a much lower net anion charge than mammalian plasma protein. An incidental finding was that total protein concentration measured by a multianalyzer system was consistently lower than the value for total solids measured by refractometer. 2. Process techniques of charge transfer time reduction for high speed CMOS image sensors International Nuclear Information System (INIS) Cao Zhongxiang; Li Quanliang; Han Ye; Qin Qi; Feng Peng; Liu Liyuan; Wu Nanjian 2014-01-01 This paper proposes pixel process techniques to reduce the charge transfer time in high speed CMOS image sensors. These techniques increase the lateral conductivity of the photo-generated carriers in a pinned photodiode (PPD) and the voltage difference between the PPD and the floating diffusion (FD) node by controlling and optimizing the N doping concentration in the PPD and the threshold voltage of the reset transistor, respectively. The techniques shorten the charge transfer time from the PPD diode to the FD node effectively. The proposed process techniques do not need extra masks and do not cause harm to the fill factor. A sub array of 32 × 64 pixels was designed and implemented in the 0.18 μm CIS process with five implantation conditions splitting the N region in the PPD. The simulation and measured results demonstrate that the charge transfer time can be decreased by using the proposed techniques. Comparing the charge transfer time of the pixel with the different implantation conditions of the N region, the charge transfer time of 0.32 μs is achieved and 31% of image lag was reduced by using the proposed process techniques. (semiconductor devices) 3. Non-Markovian reduced dynamics of ultrafast charge transfer at an oligothiophene–fullerene heterojunction Energy Technology Data Exchange (ETDEWEB) Hughes, Keith H., E-mail: keith.hughes@bangor.ac.uk [School of Chemistry, Bangor University, Bangor, Gwynedd LL57 2UW (United Kingdom); Cahier, Benjamin [School of Chemistry, Bangor University, Bangor, Gwynedd LL57 2UW (United Kingdom); Martinazzo, Rocco [Dipartimento di Chimica Università degli Studi di Milano, v. Golgi 19, 20133 Milano (Italy); Tamura, Hiroyuki [WPI-Advanced Institute for Material Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Burghardt, Irene [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main (Germany) 2014-10-17 Highlights: • Quantum dynamical study of exciton dissociation at a heterojunction interface. • The non-Markovian quantum dynamics involves a highly structured spectral density. • Spectral density is reconstructed from an effective mode transformation of the Hamiltonian. • The dynamics is studied using the hierarchical equations of motion approach. • It was found that the temperature has little effect on the charge transfer. - Abstract: We extend our recent quantum dynamical study of the exciton dissociation and charge transfer at an oligothiophene–fullerene heterojunction interface (Tamura et al., 2012) [6] by investigating the process using the non-perturbative hierarchical equations of motion (HEOM) approach. Based upon an effective mode reconstruction of the spectral density the effect of temperature on the charge transfer is studied using reduced density matrices. It was found that the temperature had little effect on the charge transfer and a coherent dynamics persists over the first few tens of femtoseconds, indicating that the primary charge transfer step proceeds by an activationless pathway. 4. Electrostatic sensors applied to the measurement of electric charge transfer in gas-solids pipelines International Nuclear Information System (INIS) Woodhead, S R; Denham, J C; Armour-Chelu, D I 2005-01-01 This paper describes the development of a number of electric charge sensors. The sensors have been developed specifically to investigate triboelectric charge transfer which takes place between particles and the pipeline wall, when powdered materials are conveyed through a pipeline using air. A number of industrial applications exist for such gas-solids pipelines, including pneumatic conveyors, vacuum cleaners and dust extraction systems. The build-up of electric charge on pipelines and powdered materials can lead to electrostatic discharge and so is of interest from a safety viewpoint. The charging of powders can also adversely affect their mechanical handling characteristics and so is of interest to handling equipment engineers. The paper presents the design of the sensors, the design of the electric charge test rig and electric charge measurement test results 5. Contribution of the net charge to the regulatory effects of amino acids and epsilon-poly(L-lysine) on the gelatinization behavior of potato starch granules. Science.gov (United States) Ito, Azusa; Hattori, Makoto; Yoshida, Tadashi; Takahashi, Koji 2006-01-01 The effects of lysine (Lys), monosodium glutamate (GluNa), glycine, alanine and epsilon-poly(L-lysine) (PL) with different degrees of polymerization on the gelatinization behavior of potato starch granules were investigated by DSC, viscosity and swelling measurements, microscopic observation, and measurement of the retained amino acid amount to clarify the contribution of the net charge to their regulatory effects on the gelatinization behavior. The amino acids and PL each contributed to an increase in the gelatinization temperature, and a decrease in the peak viscosity and swelling. These effects strongly depended on the absolute value of their net charge. The disappearance of a negative or positive net charge by adjusting the pH value weakened the contribution. The swelling index and size of the potato starch granules changed according to replacement of the swelling medium. The amino acids and PL were easily retained by the swollen potato starch granules according to replacement of the outer solution of the starch granules. 6. Analysis of solar radiation transfer: A method to estimate the porosity of a plastic shading net International Nuclear Information System (INIS) Abdel-Ghany, A.M.; Al-Helal, I.M. 2011-01-01 Plastic nets with opaque threads are frequently used for shading agricultural structures under high solar radiation conditions. A parameter that is often used to define a net is the net porosity (Π). Value of Π is usually estimated by one of three methods: image processing, direct beam transmittance, or solar radiation balance (hereafter radiation balance). Image processing is a rather slow process because it requires scanning the net sample at high resolution. The direct beam transmittance and radiation balance methods greatly overestimate Π because some of the solar radiation incident on the thread surfaces is forward scattered and add a considerable amount of radiation to that transmitted from the net pores directly. In this study, the radiation balance method was modified to estimate Π precisely. The amount of solar radiation scattered forward on the thread surfaces was estimated separately. Thus, the un-scattered solar radiation transmitted from the net pores directly, which describes the net porosity, Π could be estimated. This method, in addition to the image processing and the direct beam transmittance methods were used to estimate Π for different types of nets that are commonly used for shading structures in summer. Values of Π estimated by using the proposed method were in good accordance with those measured by the image processing method at a resolution of 4800 dpi. The direct beam transmittance and the radiation balance methods resulted in overestimation errors in the values of Π. This error strongly depends on the color of the net. The estimated errors were +14% for a green net and +37% for a white net when using the radiation balance method, and were +16% and +38%, respectively, when using the direct beam transmittance method. In the image processing method, a resolution of 2400 dpi is sufficient to estimate Π precisely and the higher resolutions showed no significant effect on the value of Π. 7. Electroluminescence from charge transfer states in Donor/Acceptor solar cells DEFF Research Database (Denmark) Sherafatipour, Golenaz; Madsen, Morten Charge photocurrent generation is a key process in solar energy conversion systems. Effective dissociation of the photo-generated electron-hole pairs (excitons) has a strong influence on the efficiency of the organic solar cells. Charge dissociation takes place at the donor/acceptor interface via...... which the maximum open-circuit voltage can be estimated, and further can be used in the modeling and optimization of the OPV devices. [1] C. Deibe, T. Strobe, and V. Dyakonov, “Role of the charge transfer state in organic donor-acceptor solar cells,” Adv. Mater., vol. 22, pp. 4097–4111, 2010. [2] K...... charge transfer (CT) excitons, which is Coulombically bound interfacial electron- hole pairs residing at the donor/acceptor heterojunctions. The CT state represents an intermediate state between the exciton dissociation and recombination back to the ground state. Since the recombination of photo... 8. A two-dimensional position sensitive gas chamber with scanned charge transfer readout International Nuclear Information System (INIS) Gomez, F.; Iglesias, A.; Lobato, R.; Mosquera, J.; Pardo, J.; Pena, J.; Pazos, A.; Pombar, M.; Rodriguez, A. 2003-01-01 We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 μm thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8x8 cm 2 with a pixel size of 1.27x1.27 mm 2 . Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring 9. High-energy behavior of the charge-transfer cross section in the eikonal approximation International Nuclear Information System (INIS) Dewangan, D.P. 1982-01-01 In the now popular version of the eikonal theory of charge transfer, the eikonal wave function does not satisfy the proper boundary conditions and the charge-transfer amplitude is uncertain by an undefined phase factor. The inclusion of the internuclear potential in a consistent way, in the eikonal theory overcomes theses difficulties. However, it also changes the high-energy asymptotic form of proton-hydrogen charge-transfer cross section from sigma/sub eik/ approx.(23/48) sigma/sub BK/ by a small amount to sigma/sub G/approx.(20.109/48)sigma/sub BK/ where sigma/sub BK/ is the Brinkman-Kramers cross section 10. Polyoxometalate active charge-transfer material for mediated redox flow battery Energy Technology Data Exchange (ETDEWEB) Anderson, Travis Mark; Hudak, Nicholas; Staiger, Chad; Pratt, Harry 2017-01-17 Redox flow batteries including a half-cell electrode chamber coupled to a current collecting electrode are disclosed herein. In a general embodiment, a separator is coupled to the half-cell electrode chamber. The half-cell electrode chamber comprises a first redox-active mediator and a second redox-active mediator. The first redox-active mediator and the second redox-active mediator are circulated through the half-cell electrode chamber into an external container. The container includes an active charge-transfer material. The active charge-transfer material has a redox potential between a redox potential of the first redox-active mediator and a redox potential of the second redox-active mediator. The active charge-transfer material is a polyoxometalate or derivative thereof. The redox flow battery may be particularly useful in energy storage solutions for renewable energy sources and for providing sustained power to an electrical grid. 11. Charge-transfer channel in quantum dot-graphene hybrid materials Science.gov (United States) Cao, Shuo; Wang, Jingang; Ma, Fengcai; Sun, Mengtao 2018-04-01 The energy band theory of a classical semiconductor can qualitatively explain the charge-transfer process in low-dimensional hybrid colloidal quantum dot (QD)-graphene (GR) materials; however, the definite charge-transfer channels are not clear. Using density functional theory (DFT) and time-dependent DFT, we simulate the hybrid QD-GR nanostructure, and by constructing its orbital interaction diagram, we show the quantitative coupling characteristics of the molecular orbitals (MOs) of the hybrid structure. The main MOs are derived from the fragment MOs (FOs) of GR, and the Cd13Se13 QD FOs merge with the GR FOs in a certain proportion to afford the hybrid system. Upon photoexcitation, electrons in the GR FOs jump to the QD FOs, leaving holes in the GR FOs, and the definite charge-transfer channels can be found by analyzing the complex MOs coupling. The excited electrons and remaining holes can also be localized in the GR or the QD or transfer between the QD and GR with different absorption energies. The charge-transfer process for the selected excited states of the hybrid QD-GR structure are testified by the charge difference density isosurface. The natural transition orbitals, charge-transfer length analysis and 2D site representation of the transition density matrix also verify the electron-hole delocalization, localization, or coherence chacracteristics of the selected excited states. Therefore, our research enhances understanding of the coupling mechanism of low-dimensional hybrid materials and will aid in the design and manipulation of hybrid photoelectric devices for practical application in many fields. 12. Charge Transfer Properties Through Graphene for Applications in Gaseous Detectors CERN Document Server Franchino, S.; Hall-Wilton, R.; Jackman, R.B.; Muller, H.; Nguyen, T.T.; de Oliveira, R.; Oliveri, E.; Pfeiffer, D.; Resnati, F.; Ropelewski, L.; Smith, J.; van Stenis, M.; Streli, C.; Thuiner, P.; Veenhof, R. 2016-07-11 Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical and electrical properties. Regarded as the thinnest and narrowest conductive mesh, it has drastically different transmission behaviours when bombarded with electrons and ions in vacuum. This property, if confirmed in gas, may be a definitive solution for the ion back-flow problem in gaseous detectors. In order to ascertain this aspect, graphene layers of dimensions of about 2x2cm$^2, grown on a copper substrate, are transferred onto a flat metal surface with holes, so that the graphene layer is freely suspended. The graphene and the support are installed into a gaseous detector equipped with a triple Gaseous Electron Multiplier (GEM), and the transparency properties to electrons and ions are studied in gas as a function of the electric fields. The techniques to produce the graphene samples are described, and we report on preliminary tests of graphene-coated GEMs. 13. Improving radiation hardness in space-based Charge-Coupled Devices through the narrowing of the charge transfer channel Science.gov (United States) Hall, D. J.; Skottfelt, J.; Soman, M. R.; Bush, N.; Holland, A. 2017-12-01 Charge-Coupled Devices (CCDs) have been the detector of choice for imaging and spectroscopy in space missions for several decades, such as those being used for the Euclid VIS instrument and baselined for the SMILE SXI. Despite the many positive properties of CCDs, such as the high quantum efficiency and low noise, when used in a space environment the detectors suffer damage from the often-harsh radiation environment. High energy particles can create defects in the silicon lattice which act to trap the signal electrons being transferred through the device, reducing the signal measured and effectively increasing the noise. We can reduce the impact of radiation on the devices through four key methods: increased radiation shielding, device design considerations, optimisation of operating conditions, and image correction. Here, we concentrate on device design operations, investigating the impact of narrowing the charge-transfer channel in the device with the aim of minimising the impact of traps during readout. Previous studies for the Euclid VIS instrument considered two devices, the e2v CCD204 and CCD273, the serial register of the former having a 50 μm channel and the latter having a 20 μm channel. The reduction in channel width was previously modelled to give an approximate 1.6× reduction in charge storage volume, verified experimentally to have a reduction in charge transfer inefficiency of 1.7×. The methods used to simulate the reduction approximated the charge cloud to a sharp-edged volume within which the probability of capture by traps was 100%. For high signals and slow readout speeds, this is a reasonable approximation. However, for low signals and higher readout speeds, the approximation falls short. Here we discuss a new method of simulating and calculating charge storage variations with device design changes, considering the absolute probability of capture across the pixel, bringing validity to all signal sizes and readout speeds. Using this method, we 14. Evidence for charge transfer in Bi-based superconductors studied by positron annihilation International Nuclear Information System (INIS) Tang, Z.; Wang, S.J.; Gao, X.H.; Ce, G.C.; Zhao, Z.X. 1993-01-01 We have measured Doppler-broadening annihilation radiation (DBAR) spectra and positron lifetimes in normal and superconducting states for three kinds of Bi-based superconductors: Bi2212, Pb-doped Bi2223, Pb- and F-doped Bi2223. The difference spectra after deconvolution between two states show a sharpening effect with increasing temperature; the F-doped sample has the greatest amplitude in difference spectra but nearly the same positron lifetimes as the Pb-doped sample. The results are interpreted in terms of charge transfer between the Cu-O and Bi-O planes. The role of oxygen defects in charge transfer is discussed. (orig.) 15. Charge transfer and excitation in high-energy ion-atom collisions International Nuclear Information System (INIS) Schlachter, A.S.; Berkner, K.H.; McDonald, R.J. 1986-11-01 Coincidence measurements of charge transfer and simultaneous projectile electron excitation provide insight into correlated two-electron processes in energetic ion-atom collisions. Projectile excitation and electron capture can occur simultaneously in a collision of a highly charged ion with a target atom; this process is called resonant transfer and excitation (RTE). The intermediate excited state which is thus formed can subsequently decay by photon emission or by Auger-electron emission. Results are shown for RTE in both the K shell of Ca ions and the L shell of Nb ions, for simultaneous projectile electron loss and excitation, and for the effect of RTE on electron capture 16. Photoinduced charge transfer within polyaniline-encapsulated quantum dots decorated on graphene. Science.gov (United States) Nguyen, Kim Truc; Li, Dehui; Borah, Parijat; Ma, Xing; Liu, Zhaona; Zhu, Liangliang; Grüner, George; Xiong, Qihua; Zhao, Yanli 2013-08-28 A new method to enhance the stability of quantum dots (QDs) in aqueous solution by encapsulating them with conducting polymer polyaniline was reported. The polyaniline-encapsulated QDs were then decorated onto graphene through π-π interactions between graphene and conjugated polymer shell of QDs, forming stable polyaniline/QD/graphene hybrid. A testing electronic device was fabricated using the hybrid in order to investigate the photoinduced charge transfer between graphene and encapsulated QDs within the hybrid. The charge transfer mechanism was explored through cyclic voltammetry and spectroscopic studies. The hybrid shows a clear response to the laser irradiation, presenting a great advantage for further applications in optoelectronic devices. 17. Symmetric resonance double charge transfer in Kr++ + Kr and Xe++ + Xe systems International Nuclear Information System (INIS) Okuno, K.; Koizumi, T.; Kaneko, Y. 1978-01-01 Cross sections of processes Kr ++ + Kr → Ke + Kr ++ and Xe ++ + Xe → Xe + Xe ++ were measured by the injected-ion-drift-tube technique from 0.04 to 20 eV. For both cases, the cross section below 1 eV coincides with the orbiting cross sections with a charge-transfer probability 1/2. Above 1 eV, the energy dependence of the cross sectcion is like that for single charge transfer. Mobilities of Kr ++ and Xe ++ in He are presented also 18. Heat transfer from the evaporator outlet to the charge of thermostatic expansion valves DEFF Research Database (Denmark) Langmaack, Lasse Nicolai; Knudsen, Hans-Jørgen Høgaard 2006-01-01 outlet with a special mounting strap. The heat transfer is quite complex because it takes place both directly through the contact points between bulb and pipe and indirectly through the mounting strap The TXV has to react to temperature changes at the evaporator outlet. Therefore, the dynamic behavior...... of the valve (and thereby the whole refrigeration system) depends greatly on the heat transfer between the evaporator outlet tube and the charge in the bulb. In this paper a model for the overall heat transfer between the pipe and the charge is presented. Geometrical data and material properties have been kept...... been found to predict the time constant for the temperature development in the bulb within 1-10 %. Furthermore it has been found that app. 20% of the heat transfer takes place trough the mounting strap.... 19. Structural dynamics of a noncovalent charge transfer complex from femtosecond stimulated Raman spectroscopy. Science.gov (United States) Fujisawa, Tomotsumi; Creelman, Mark; Mathies, Richard A 2012-09-06 Femtosecond stimulated Raman spectroscopy is used to examine the structural dynamics of photoinduced charge transfer within a noncovalent electron acceptor/donor complex of pyromellitic dianhydride (PMDA, electron acceptor) and hexamethylbenzene (HMB, electron donor) in ethylacetate and acetonitrile. The evolution of the vibrational spectrum reveals the ultrafast structural changes that occur during the charge separation (Franck-Condon excited state complex → contact ion pair) and the subsequent charge recombination (contact ion pair → ground state complex). The Franck-Condon excited state is shown to have significant charge-separated character because its vibrational spectrum is similar to that of the ion pair. The charge separation rate (2.5 ps in ethylacetate and ∼0.5 ps in acetonitrile) is comparable to solvation dynamics and is unaffected by the perdeuteration of HMB, supporting the dominant role of solvent rearrangement in charge separation. On the other hand, the charge recombination slows by a factor of ∼1.4 when using perdeuterated HMB, indicating that methyl hydrogen motions of HMB mediate the charge recombination process. Resonance Raman enhancement of the HMB vibrations in the complex reveals that the ring stretches of HMB, and especially the C-CH(3) deformations are the primary acceptor modes promoting charge recombination. 20. Transverse Schottky spectra and beam transfer functions of coasting ion beams with space charge International Nuclear Information System (INIS) Paret, Stefan 2010-01-01 A study of the transverse dynamics of coasting ion beams with moderate space charge is presented in this work. From the dispersion relation with linear space charge, an analytic model describing the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam is derived. The dielectric function obtained in this way is employed to describe the transverse Schottky spectra with linear space charge as well. The difference between the action of space charge and impedances is highlighted. The setup and the results of an experiment performed in the heavy ion synchrotron SIS-18 at GSI to detect space-charge effects at different beam intensities are explicated. The measured transverse Schottky spectra and BTFs are compared with the linear space-charge model. The stability diagrams constructed from the BTFs are presented. The space-charge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. The impact of collective effects on the Schottky and BTF diagnostics is also investigated through numerical simulations. For this purpose the self-field of beams with linear and non-linear transverse density-distributions is computed on a twodimensional grid. The noise of the random particle distribution causes fluctuations of the dipole moment of the beam which produce the Schottky spectrum. BTFs are simulated by exciting the beam with transverse kicks. The simulation results are used to verify the space-charge model. (orig.) 1. Transverse Schottky spectra and beam transfer functions of coasting ion beams with space charge Energy Technology Data Exchange (ETDEWEB) Paret, Stefan 2010-02-22 A study of the transverse dynamics of coasting ion beams with moderate space charge is presented in this work. From the dispersion relation with linear space charge, an analytic model describing the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam is derived. The dielectric function obtained in this way is employed to describe the transverse Schottky spectra with linear space charge as well. The difference between the action of space charge and impedances is highlighted. The setup and the results of an experiment performed in the heavy ion synchrotron SIS-18 at GSI to detect space-charge effects at different beam intensities are explicated. The measured transverse Schottky spectra and BTFs are compared with the linear space-charge model. The stability diagrams constructed from the BTFs are presented. The space-charge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. The impact of collective effects on the Schottky and BTF diagnostics is also investigated through numerical simulations. For this purpose the self-field of beams with linear and non-linear transverse density-distributions is computed on a twodimensional grid. The noise of the random particle distribution causes fluctuations of the dipole moment of the beam which produce the Schottky spectrum. BTFs are simulated by exciting the beam with transverse kicks. The simulation results are used to verify the space-charge model. (orig.) 2. Transfer of energy or charge between quasi-zero-dimensional nanostructures Czech Academy of Sciences Publication Activity Database Král, Karel; Menšík, Miroslav 2016-01-01 Roč. 45, č. 4 (2016), s. 243-255 ISSN 2332-4309 R&D Projects: GA ČR(CZ) GA14-05053S; GA MŠk(CZ) LD14011; GA MŠk LH12236 Institutional support: RVO:68378271 ; RVO:61389013 Keywords : charge transfer * electron-phonon interaction * energy transfer * nanostructures * quantum dots Subject RIV: BM - Solid Matter Physics ; Magnetism; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 0.171, year: 2016 3. Correction: Towards the rationalization of catalytic activity values by means of local hyper-softness on the catalytic site: a criticism about the use of net electric charges. Science.gov (United States) Martínez-Araya, Jorge Ignacio; Grand, André; Glossman-Mitnik, Daniel 2016-01-28 Correction for 'Towards the rationalization of catalytic activity values by means of local hyper-softness on the catalytic site: a criticism about the use of net electric charges' by Jorge Ignacio Martínez-Araya et al., Phys. Chem. Chem. Phys., 2015, DOI: 10.1039/c5cp03822g. 4. Coupled quantum treatment of vibrationally inelastic and vibronic charge transfer in proton-O2 collisions International Nuclear Information System (INIS) Gianturco, F.A.; Palma, A.; Semprini, E.; Stefani, F.; Baer, M. 1990-01-01 A three-dimensional quantum-mechanical study of vibrational, state-resolved differential cross sections (DCS) for the direct inelastic and for the charge-transfer scattering channels has been carried out for the H + +O 2 system. The collision energy considered was E c.m. =23.0 eV, which is the same as that examined by Noll and Toennies in their experiments [J. Chem. Phys. 85, 3313 (1986)]. The scattering treatment employed was the charge-transfer infinite-order sudden approximation (CT IOSA) with the vibrational states correctly expanded over the relevant adiabatic basis for each of the two electronic channels. The state-to-state DCS are found to follow closely the behavior of the experimental quantities, both in the inelastic and the charge-transfer channels. Moreover, a careful comparison between the measured relative probabilities and computed values allows us to test in minute detail the efficiency of the scattering model and the reliability of the potential-energy surfaces employed. It is found that vibrational energy transfer is overestimated in the vibrational inelastic channels while in the charge-transfer inelastic channels the same energy transfer is slightly underestimated by the calculations. The total flux distribution, however, is found to be in very good accord with experiments. Angular distributions are also well reproduced both by the DCS and by the average energy-transfer values. The study of some of the CT IOSA quantities also allows us to establish clearly the importance of nonadiabatic transitions in enhancing vibrational inelasticity in the present system 5. Changes in wetting and contact charge transfer by femtosecond laser-ablation of polyimide Energy Technology Data Exchange (ETDEWEB) Guo, X.D., E-mail: xiaodong.guo@uib.no [Department of Physics and Technology, Allegaten 55, 5020 Bergen, University of Bergen (Norway); Dai, Y.; Gong, M. [Department of Physics, Shanghai 200444, Shanghai University (China); Qu, Y.G. [Center for Geobiology, Allegaten 41, 5020 Bergen, University of Bergen (Norway); Helseth, L.E. [Department of Physics and Technology, Allegaten 55, 5020 Bergen, University of Bergen (Norway) 2015-09-15 Highlights: • Laser ablation significantly reduced the triboelectric charging of polyimide films. • Hierarchical micro/nanostructures formed on the surface of the sample. • Structural anisotropy leads to spatially varying contact angles of water droplets. • Raman spectroscopy revealed a carbonization of the polyimide sample. • The corresponding loss of insulation may explain the reduction of charge transfer. - Abstract: In this study it is demonstrated that the triboelectric charging of polyimide thin films is significantly reduced by using a femtosecond laser to nanostructure its. It is found that the contact charge transfer between laser-ablated Kapton and aluminum is almost negligible, and even much lower than the significant current occurring when non-treated Kapton touches the metal. Scanning electron microscopy demonstrates that laser ablation produces a hierarchical micro and nanostructure, and it is found that the structural anisotropy leads to spatially varying contact angles of water droplets residing on the surface. Raman spectra suggest that the centers of the laser-ablated tracks are carbonized; therefore, the loss of insulation can be responsible for the reduction of charge transfer. 6. Charge transfer to a dielectric target by guided ionization waves using electric field measurements NARCIS (Netherlands) Slikboer, E.T.; Garcia-Caurel, E.; Guaitella, O.; Sobota, A. 2017-01-01 A kHz-operated atmospheric pressure plasma jet is investigated by measuring charge transferred to a dielectric electro-optic surface (BSO crystal) allowing for the measurement of electric field by exploiting the Pockels effect. The electric field values, distribution of the surface discharge and 7. Mechanism and Dynamics of Charge Transfer in Donor-Bridge-Acceptor Systems NARCIS (Netherlands) Gorczak-Vos, N. 2016-01-01 Photoinduced charge transfer in organic materials is a fundamental process in various biological and technological areas. Donor-bridge-acceptor (DBA) molecules are used as model systems in numerous theoretical and experimental work to systematically study and unravel the underlying mechanisms of 8. Simple heuristic derivation of some charge-transfer probabilities at asymptotically high incident velocities International Nuclear Information System (INIS) Spruch, L.; Shakeshaft, R. 1984-01-01 For asymptotically high incident velocities we provide simple, heuristic, almost classical, derivations of the cross section for forward charge transfer, and of the ratio of the cross section for capture to the elastic-scattering cross section for the projectile scattered through an angle close to π/3 9. Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts DEFF Research Database (Denmark) Sing, M.; Schwingenschlögl, U.; Claessen, R. 2003-01-01 We have thoroughly characterized the surfaces of the organic charge-transfer salts TTF-TCNQ and (TMTSF)(2)PF6 which are generally acknowledged as prototypical examples of one-dimensional conductors. In particular x-ray-induced photoemission spectroscopy turns out to be a valuable nondestructive... 10. Charge distribution effects in polyatomic reactants involved in simple electron transfer reactions Czech Academy of Sciences Publication Activity Database Fawcett, W. R.; Chavis, G. J.; Hromadová, Magdaléna 2008-01-01 Roč. 53, č. 23 (2008), s. 6787-6792 ISSN 0013-4686 Institutional research plan: CEZ:AV0Z40400503 Keywords : electron transfer kinetics * charge distribution effects * double - layer effects in electrode kinetics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.078, year: 2008 11. Integer charge transfer at the tetrakis(dimethylamino)ethylene/Au interface DEFF Research Database (Denmark) Lindell, L.; Unge, Mikael; Osikowicz, W. 2008-01-01 In organic-based electronics, interfacial properties have a profound impact on device performance. The lineup of energy levels is usually dependent on interface dipoles, which may arise from charge transfer reactions. In many applications, metal-organic junctions are prepared under ambient... 12. Charge transfer state in DBP:C70 organic solar cells DEFF Research Database (Denmark) Sherafatipour, Golenaz; Benduhn, Johannes; Spoltore, Donato -acceptor interface via delocalized charge-transfer (CT) states, which represents an intermediate state between the exciton dissociation and recombination back to the ground state. In this work we perform the electroluminescence (EL) created by bimolecular free career recombination and sensitive external quantum... 13. Elastic, excitation, ionization and charge transfer cross sections of current interest in fusion energy research Energy Technology Data Exchange (ETDEWEB) Schultz, D.R.; Krstic, P.S. [Oak Ridge National Lab. TN (United States). Physics Div. 1997-01-01 Due to the present interest in modeling and diagnosing the edge and divertor plasma regions in magnetically confined fusion devices, we have sought to provide new calculations regarding the elastic, excitation, ionization, and charge transfer cross sections in collisions among relevant ions, neutrals, and isotopes in the low-to intermediate-energy regime. We summarize here some of our recent work. (author) 14. Charge transfer to the continuum by heavy ions in atomic hydrogen International Nuclear Information System (INIS) Sellin, I.A. 1981-01-01 Design and installation of an atomic hydrogen target for measurements of charge transfer to the continuum by heavy ions are discussed. The design consists of a tungsten gas cell operated at temperatures of 2500 to 2600 0 K. Initial testing is underway 15. Mechanism of the Primary Charge Transfer Reaction in the Cytochrome bc1 Complex DEFF Research Database (Denmark) Barragan, Angela M; Schulten, Klaus; Solov'yov, Ilia A 2016-01-01 , the quinol-protein interaction, which initiates the Q-cycle, has not yet been completely described. Furthermore, the initial charge transfer reactions of the Q-cycle lack a physical description. The present investigation utilizes classical molecular dynamics simulations in tandem with quantum density... 16. The description of charge transfer in fast negative ions scattering on water covered Si(100) surfaces Energy Technology Data Exchange (ETDEWEB) Chen, Lin; Qiu, Shunli; Liu, Pinyang; Xiong, Feifei; Lu, Jianjie; Liu, Yuefeng; Li, Guopeng; Liu, Yiran; Ren, Fei; Xiao, Yunqing; Gao, Lei; Zhao, Qiushuang; Ding, Bin; Li, Yuan [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China); Guo, Yanling, E-mail: guoyanling@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China); Chen, Ximeng, E-mail: chenxm@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, 730000 (China) 2016-11-30 Highlights: • We first observe that negative-ion fractions present no variation with the doping concentration, which is very different from the results of low energy Li neutralization from doped Si samples. • Our work shows that the affinity levels and collision time significantly counteract the band gap effect on negative ion formation. The work will improve our understanding on electron transfer on semiconductor surfaces associated with doping. • In addition, we build a complete theoretical framework to quantitatively calculate the negative-ion fractions. • Our work is related to charge transfer on semiconductor surfaces, which will be of interest to a broad audience due to the wide necessity of the knowledge of charge exchange on semiconductor surfaces in different fields. - Abstract: Doping has significantly affected the characteristics and performance of semiconductor electronic devices. In this work, we study the charge transfer processes for 8.5–22.5 keV C{sup −} and F{sup −} ions scattering on H{sub 2}O-terminated p-type Si(100) surfaces with two different doping concentrations. We find that doping has no influence on negative-ion formation for fast collisions in this relatively high energy range. Moreover, we build a model to calculate negative ion fractions including the contribution from positive ions. The calculations support the nonadiabatic feature of charge transfer. 17. Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads KAUST Repository Whited, Matthew T.; Patel, Niral M.; Roberts, Sean T.; Allen, Kathryn; Djurovich, Peter I.; Bradforth, Stephen E.; Thompson, Mark E. 2012-01-01 We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl. 18. Reduced Charge Transfer Exciton Recombination in Organic Semiconductor Heterojunctions by Molecular Doping NARCIS (Netherlands) Deschler, Felix; Da Como, Enrico; Limmer, Thomas; Tautz, Raphael; Godde, Tillmann; Bayer, Manfred; von Hauff, Elizabeth; Yilmaz, Seyfullah; Allard, Sybille; Scherf, Ullrich; Feldmann, Jochen 2011-01-01 We investigate the effect of molecular doping on the recombination of electrons and holes localized at conjugated-polymer–fullerene interfaces. We demonstrate that a low concentration of p-type dopant molecules (<4% weight) reduces the interfacial recombination via charge transfer excitons and 19. Enhanced intersystem crossing via a high energy charge transfer state in a perylenediimide-perylenemonoimide dyad NARCIS (Netherlands) Veldman, D.; Chopin-Cado, S.M.A; Meskers, S.C.J.; Janssen, R.A.J. 2008-01-01 The electronic relaxation processes of a photoexcited linear perylenediimide-perylenemonoimide (PDI-PMI) acceptor-donor dyad were studied. PDI-PMI serves as a model compound for donor-acceptor systems in photovoltaic devices and has been designed to have a high-energy PDI--PMI + charge transfer (CT) 20. Charge transfer between hydrogen(deuterium) ions and atoms in metal vapors International Nuclear Information System (INIS) Alvarez T, I.; Cisneros G, C. 1981-01-01 The current state of the experiments on charge transfer between hydrogen (deuterium) ions and atoms in metal vapors are given. Emphasis is given to describing different experimental techniques. The results of calculations if available, are compared with existing experimental data. (author) 1. Radiative charge-transfer lifetime of the excited state of (NaCa)+ International Nuclear Information System (INIS) Makarov, Oleg P.; Cote, R.; Michels, H.; Smith, W.W. 2003-01-01 New experiments were proposed recently to investigate the regime of cold atomic and molecular ion-atom collision processes in a special hybrid neutral-atom-ion trap under high-vacuum conditions. We study the collisional cooling of laser precooled Ca + ions by ultracold Na atoms. Modeling this process requires knowledge of the radiative lifetime of the excited singlet A 1 Σ + state of the (NaCa) + molecular system. We calculate the rate coefficient for radiative charge transfer using a semiclassical approach. The dipole radial matrix elements between the ground and the excited states, and the potential curves were calculated using complete active space self-consistent field and Moeller-Plesset second-order perturbation theory with an extended Gaussian basis, 6-311+G (3df). The semiclassical charge-transfer rate coefficient was averaged over a thermal Maxwellian distribution. In addition, we also present elastic collision cross sections and the spin-exchange cross section. The rate coefficient for charge transfer was found to be 2.3x10 -16 cm 3 /sec, while those for the elastic and spin-exchange cross sections were found to be several orders of magnitude higher (1.1x10 -8 cm 3 /sec and 2.3x10 -9 cm 3 /sec, respectively). This confirms our assumption that the milli-Kelvin regime of collisional cooling of calcium ions by sodium atoms is favorable with the respect to low loss of calcium ions due to the charge transfer 2. Effects of Charge-Transfer Excitons on the Photophysics of Organic Semiconductors Science.gov (United States) Hestand, Nicholas J. The field of organic electronics has received considerable attention over the past several years due to the promise of novel electronic materials that are cheap, flexible and light weight. While some devices based on organic materials have already emerged on the market (e.g. organic light emitting diodes), a deeper understanding of the excited states within the condensed phase is necessary both to improve current commercial products and to develop new materials for applications that are currently in the commercial pipeline (e.g. organic photovoltaics, wearable displays, and field effect transistors). To this end, a model for pi-conjugated molecular aggregates and crystals is developed and analyzed. The model considers two types of electronic excitations, namely Frenkel and charge-transfer excitons, both of which play a prominent role in determining the nature of the excited states within tightly-packed organic systems. The former consist of an electron-hole pair bound to the same molecule while in the later the electron and hole are located on different molecules. The model also considers the important nuclear reorganization that occurs when the system switches between electronic states. This is achieved using a Holstein-style Hamiltonian that includes linear vibronic coupling of the electronic states to the nuclear motion associated with the high frequency vinyl-stretching and ring-breathing modes. Analysis of the model reveals spectroscopic signatures of charge-transfer mediated J- and H-aggregation in systems where the photophysical properties are determined primarily by charge-transfer interactions. Importantly, such signatures are found to be sensitive to the relative phase of the intermolecular electron and hole transfer integrals, and the relative energy of the Frenkel and charge-transfer states. When the charge-transfer integrals are in phase and the energy of the charge-transfer state is higher than the Frenkel state, the system exhibits J 3. Temperature dependence of positronium reactivities with charge transfer molecules in bilayer membranes International Nuclear Information System (INIS) Jean, Y.C.; Yu, C.; Wang, Y.Y.; Yeh, Y.Y. 1984-01-01 Rate constants for positronium atoms reacting chemically with charge-transfer molecules such as p-benzoquinone, nitrobenzene, and coenzyme Q-10 in a model bilayer membrane, dipalmitoylphosphatidylcholine (DPPC), have been measured at temperatures between 23 and 65 0 C. A strong variation of the positronium chemical reactivities, k/sub Ps/ was observed in these systems: k/sub Ps/ increases with increasing temperature until the pretransition temperature of the membrane reaches a maximum value near the main transition temperature and decreases at temperatures higher than the main transition temperature. This variation is interpreted in terms of fluidity and permeability changes associated with the phase transitions of membranes and in terms of charge-transfer-complex formation between the solubilized molecules and the polar head of the membrane. These results demonstrate that positronium and its annihilation characteristics can be employed to investigate charge transport phenomena and microstructural changes of real biological membranes 4. A schematic model for energy and charge transfer in the chlorophyll complex DEFF Research Database (Denmark) Bohr, Henrik; Malik, F.B. 2011-01-01 A theory for simultaneous charge and energy transfer in the carotenoid-chlorophyll-a complex is presented here and discussed. The observed charge transfer process in these chloroplast complexes is reasonably explained in terms of this theory. In addition, the process leads to a mechanism to drive...... an electron in a lower to a higher-energy state, thus providing a mechanism for the ejection of the electron to a nearby molecule (chlorophyll) or into the environment. The observed lifetimes of the electronically excited states are in accord/agreement with the investigations of Sundström et al....... and are in the range of pico-seconds and less. The change in electronic charge distribution in internuclear space as the system undergoes an electronic transition to a higher-energy state could, under appropriate physical conditions, lead to oscillating dipoles capable of transmitting energy from the carotenoid-chlorophylls... 5. Charge Transfer Effect on Raman and Surface Enhanced Raman Spectroscopy of Furfural Molecules. Science.gov (United States) Wan, Fu; Shi, Haiyang; Chen, Weigen; Gu, Zhaoliang; Du, Lingling; Wang, Pinyi; Wang, Jianxin; Huang, Yingzhou 2017-08-02 The detection of furfural in transformer oil through surface enhanced Raman spectroscopy (SERS) is one of the most promising online monitoring techniques in the process of transformer aging. In this work, the Raman of individual furfural molecules and SERS of furfural-M x (M = Ag, Au, Cu) complexes are investigated through density functional theory (DFT). In the Raman spectrum of individual furfural molecules, the vibration mode of each Raman peak is figured out, and the deviation from experimental data is analyzed by surface charge distribution. In the SERS of furfural-M x complexes, the influence of atom number and species on SERS chemical enhancement factors (EFs) are studied, and are further analyzed by charge transfer effect. Our studies strengthen the understanding of charge transfer effect in the SERS of furfural molecules, which is important in the online monitoring of the transformer aging process through SERS. 6. Extraordinary Mechanism of the Diels-Alder Reaction: Investigation of Stereochemistry, Charge Transfer, Charge Polarization, and Biradicaloid Formation. Science.gov (United States) Sexton, Thomas; Kraka, Elfi; Cremer, Dieter 2016-02-25 The Diels-Alder reaction between 1,3-butadiene and ethene is investigated from far-out in the entrance channel to the very last step in the exit channel thus passing two bifurcation points and extending the range of the reaction valley studied with URVA (Unified Reaction Valley Approach) by 300% compared to previous studies. For the first time, the pre- and postchemical steps of the reaction are analyzed at the same level of theory as the actual chemical processes utilizing the path curvature and its decomposition into internal coordinate or curvilinear coordinate components. A first smaller charge transfer to the dienophile facilitates the rotation of gauche butadiene into its cis form. The actual chemical processes are initiated by a second larger charge transfer to the dienophile that facilitates pyramidalization of the reacting carbon centers, bond equalization, and biradicaloid formation of the reactants. The transition state is aromatically stabilized and moved by five path units into the entrance channel in line with the Hammond-Leffler postulate. The pseudorotation of the boat form into the halfchair of cyclohexene is analyzed. Predictions are made for the Diels-Alder reaction based on a 11-phase mechanism obtained by the URVA analysis. 7. Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses Directory of Open Access Journals (Sweden) Rebecca Boll 2016-07-01 Full Text Available Ultrafast electron transfer in dissociating iodomethane and fluoromethane molecules was studied at the Linac Coherent Light Source free-electron laser using an ultraviolet-pump, X-ray-probe scheme. The results for both molecules are discussed with respect to the nature of their UV excitation and different chemical properties. Signatures of long-distance intramolecular charge transfer are observed for both species, and a quantitative analysis of its distance dependence in iodomethane is carried out for charge states up to I21+. The reconstructed critical distances for electron transfer are in good agreement with a classical over-the-barrier model and with an earlier experiment employing a near-infrared pump pulse. 8. Ion-atom charge-transfer system for a heavy-ion-beam pumped laser International Nuclear Information System (INIS) Ulrich, A.; Gernhaeuser, R.; Kroetz, W.; Wieser, J.; Murnick, D.E. 1994-01-01 An Ar target to which Cs vapor could be added, excited by a pulsed beam of 100-MeV 32 S ions, was studied as a prototype ion-atom charge-transfer system for pumping short-wavelength lasers. Low-velocity Ar 2+ ions were efficiently produced; a huge increase in the intensity of the Ar II 4d-4p spectral lines was observed when Cs vapor was added to the argon. This observation is explained by a selective charge transfer of the Cs 6s electron into the upper levels of the observed transitions. A rate constant of (1.4±0.2)x10 -9 cm 3 /s for the transfer process was determined 9. Synthetic system mimicking the energy transfer and charge separation of natural photosynthesis Energy Technology Data Exchange (ETDEWEB) Gust, D.; Moore, T.A. 1985-05-01 A synthetic molecular triad consisting of a porphyrin P linked to both a quinone Q and a carotenoid polyene C has been prepared as a mimic of natural photosynthesis for solar energy conversion purposes. Laser flash excitation of the porphyrin moiety yields a charge-separated state Csup(+.)-P-Qsup(-.) within 100 ps with a quantum yield of more than 0.25. This charge-separated state has a lifetime on the microsecond time scale in suitable solvents. The triad also models photosynthetic antenna function and photoprotection from singlet oxygen damge. The successful biomimicry of photosynthetic charge separation is in part the result of multistep electron transfers which rapidly separate the charges and leave the system at high potential, but with a considerable barrier to recombination. 10. Theoretical Study of the Charge-Transfer State Separation within Marcus Theory DEFF Research Database (Denmark) Volpi, Riccardo; Nassau, Racine; Nørby, Morten Steen 2016-01-01 We study, within Marcus theory, the possibility of the charge-transfer (CT) state splitting at organic interfaces and a subsequent transport of the free charge carriers to the electrodes. As a case study we analyze model anthracene-C60 interfaces. Kinetic Monte Carlo (KMC) simulations on the cold...... CT state were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface to simulate the action of the electric field in a bulk heterojunction (BHJ) interface. The results show that the inclusion of polarization in our model increases CT state...... dissociation and charge collection. The effect of the electric field on CT state splitting and free charge carrier conduction is analyzed in detail with and without polarization. Also, depending on the relative orientation of the anthracene and C60 molecules at the interface, CT state splitting shows different... 11. Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter Science.gov (United States) Fossum, Eric R. (Inventor); Mendis, Sunetra K. (Inventor); Pain, Bedabrata (Inventor); Nixon, Robert H. (Inventor); Zhou, Zhimin (Inventor) 2003-01-01 An imaging device formed as a monolithic complementary metal oxide semiconductor integrated circuit in an industry standard complementary metal oxide semiconductor process, the integrated circuit including a focal plane array of pixel cells, each one of the cells including a photogate overlying the substrate for accumulating photo-generated charge in an underlying portion of the substrate, a readout circuit including at least an output field effect transistor formed in the substrate, and a charge coupled device section formed on the substrate adjacent the photogate having a sensing node connected to the output transistor and at least one charge coupled device stage for transferring charge from the underlying portion of the substrate to the sensing node and an analog-to-digital converter formed in the substrate connected to the output of the readout circuit. 12. Charge and energy transfer interplay in hybrid sensitized solar cells mediated by graphene quantum dots International Nuclear Information System (INIS) Mihalache, Iuliana; Radoi, Antonio; Mihaila, Mihai; Munteanu, Cornel; Marin, Alexandru; Danila, Mihai; Kusko, Mihaela; Kusko, Cristian 2015-01-01 Highlights: • We report a one pot synthesis metod of GQD with controlled size and optoelectronic properties. • An improvement of common N3-DSSC characteristics is achieved when GQDs are used as co-sensitiser. • The role of GQD as cosensitisers in hybrid DSSC was investigated and the interplay between charge and energy transfer phenomena mediated by GQDs was demonstrated. • The GQDs presence determines an inhibition of the recombination processes at the TiO 2 /electrolyte interface. - Abstract: We explored the role of graphene quantum dots (GQDs) as co-sensitizers in hybrid dye sensitized solar cell (DSSC) architectures, focusing on various concurring mechanisms, such as: charge transfer, energy transfer and recombination rate, towards light harvesting improvement. GQDs were prepared by the hydrothermal method that allows the tuning of electronic levels and optical properties by employing appropriate precursors and synthesis conditions. The aim was to realize a type II alignment for TiO 2 /GQD/dye hybrid configuration, using standard N3 Ru-dye in order to improve charge transfer. When GQDs were used as co-sensitizers together with N3 Ru-dye, an improvement in power conversion efficiency was achieved, as shown by electrical measurements. The experimental analysis indicates that this improvement arises from the interplay of various mechanisms mediated by GQDs: (i) enhancement of charge separation and collection due to the cascaded alignment of the energy levels; (ii) energy transfer from GQDs to N3 Ru-dye due to the overlap between GQD photoluminescence and N3 Ru-dye absorption spectra; and (iii) reduction of the electron recombination to the redox couple due to the inhibition of the back electron transfer to the electrolyte by the GQDs 13. Energy and charge transfer cascade in methylammonium lead bromide perovskite nanoparticle aggregates. Science.gov (United States) Bouduban, Marine E F; Burgos-Caminal, Andrés; Ossola, Rachele; Teuscher, Joël; Moser, Jacques-E 2017-06-01 Highly photoluminescent hybrid lead halide perovskite nanoparticles have recently attracted wide interest in the context of high-stake applications, such as light emitting diodes (LEDs), light emitting transistors and lasers. In addition, they constitute ideal model systems to explore energy and charge transport phenomena occurring at the boundaries of nanocrystalline grains forming thin films in high-efficiency perovskite solar cells (PSCs). Here we report a complete photophysical study of CH 3 NH 3 PbBr 3 perovskite nanoparticles suspended in chlorobenzene and highlight some important interaction properties. Colloidal suspensions under study were constituted of dispersed aggregates of quasi-2D platelets of a range of thicknesses, decorated with 3D-like spherical nanoparticles. These types of nanostructures possess different optical properties that afford a handle for probing them individually. The photophysics of the colloidal particles was studied by femtosecond pump-probe spectroscopy and time-correlated single-photon counting. We show here that a cascade of energy and exciton-mediated charge transfer occurs between nanostructures: upon photoexcitation, localized excitons within one nanostructure can either recombine on a ps timescale, yielding a short-lived emission, or form charge-transfer states (CTSs) across adjacent domains, resulting in longer-lived photoluminescence in the millisecond timescale. Furthermore, CTSs exhibit a clear signature in the form of a strong photoinduced electroabsorption evidenced in femtosecond transient absorption measurements. Charge transfer dynamics at the surface of the nanoparticles have been studied with various quenchers in solution. Efficient hole transfer to N , N , N ', N '-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD) and 1,4-bis(diphenyl-amino)benzene (BDB) donors was attested by the quenching of the nanoparticles emission. The charge transfer rate was limited by the organic layer used to stabilize the nanoparticles 14. A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence DEFF Research Database (Denmark) Chabera, Pavel; Liu, Yizhu; Prakash, Om 2017-01-01 Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes... 15. Photo-induced charge transfer at heterogeneous interfaces: Dye-sensitized tin disulfide, the theory and the experiment International Nuclear Information System (INIS) Lanzafame, J.M. 1993-01-01 The study of photo-induced charge transfer is an endeavor that spans the entire industrial period of man's history. Its great importance demands an ever greater understanding of its underlying principles. The work discussed here attempts to probe elementary aspects of the charge transfer process. Investigations into the theory of charge transfer reactions are made in an attempt to isolate the relevant parameters. An analytical discussion is made of a simple Golden Rule type rate equation to describe the transfer kinetics. Then a quantum simulation is carried out to follow the wavefunction propagation as a test of the applicability of the assumptions made in deriving the simpler rate equation. Investigation of charge transfer at surfaces is bet served by the application of ultrafast optical spectroscopies to probe carrier dynamics. A discussion of the properties of the short pulse laser systems employed is included along with a discussion of the different optical spectroscopies available. These tools are then brought to bear upon dye-sensitized SnS 2 , a model system for the study of charge injection processes. The unique properties of the semiconductor are discussed with respect to the charge transfer process. The unique properties of the semiconductor are discussed with respect to the charge transfer process. The optical experiments performed on the dye/SnS 2 systems elucidate the fundamental carrier dynamics and these dynamics are discussed within the theoretical framework to provide a complete picture of the charge transfer kinetics 16. Study Of Higher Moments Of Net-Electric Charge & Net-Proton Number Fluctuations In Pb+Pb Collisions At\\sqrt{s_{NN}}$=2.76 TeV In ALICE At LHC CERN Document Server Behera, Nirbhay Kumar Lattice QCD predicts that at extreme temperature and energy density, QCD matter will undergo a phase transition from hadronic matter to partonic matter called as QGP. One of the fundamental goals of heavy ion collision experiments to map the QCD phase diagram as a function of temperature (T) and baryo-chemical potential ($\\mu_{B}$). There are many proposed experimental signatures of QGP and fluctuations study are regarded as sensitive tool for it. It is proposed that fluctuation of conserved quantities like net-charge and net-proton can be used to map the QCD phase diagram. The mean ($\\mu$), sigma ($\\sigma$), skewness (S) and kurtosis ($\\kappa$) of the distribution of net charge and net proton are believed to be sensitive probes in fluctuation analysis. It has been argued that critical phenomena are signaled with increase and divergence of correlation length. The dependence of$n^{th}$order higher moments (cumulants,$c_{n}$) with the correlation length$\\xi$is as$c_{n}\\sim\\xi^{2.5n-3}. At LHC energy, the... 17. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer Energy Technology Data Exchange (ETDEWEB) Yao, Yi; Berkowitz, Max L., E-mail: maxb@unc.edu, E-mail: ykanai@unc.edu; Kanai, Yosuke, E-mail: maxb@unc.edu, E-mail: ykanai@unc.edu [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 (United States) 2015-12-28 The translational diffusivity of water in solutions of alkali halide salts depends on the identity of ions, exhibiting dramatically different behavior even in solutions of similar salts of NaCl and KCl. The water diffusion coefficient decreases as the salt concentration increases in NaCl. Yet, in KCl solution, it slightly increases and remains above bulk value as salt concentration increases. Previous classical molecular dynamics simulations have failed to describe this important behavior even when polarizable models were used. Here, we show that inclusion of dynamical charge transfer among water molecules produces results in a quantitative agreement with experiments. Our results indicate that the concentration-dependent diffusivity reflects the importance of many-body effects among the water molecules in aqueous ionic solutions. Comparison with quantum mechanical calculations shows that a heterogeneous and extended distribution of charges on water molecules around the ions due to ion-water and also water-water charge transfer plays a very important role in controlling water diffusivity. Explicit inclusion of the charge transfer allows us to model accurately the difference in the concentration-dependent water diffusivity between Na{sup +} and K{sup +} ions in simulations, and it is likely to impact modeling of a wide range of systems for medical and technological applications. 18. Failures of TDDFT in describing the lowest intramolecular charge-transfer excitation in para-nitroanilin DEFF Research Database (Denmark) Eriksen, J.J.; Sauer, S.P.A.; Mikkelsen, K.V. 2013-01-01 We investigate the failure of Time{Dependent Density Functional Theory (TDDFT) with the CAM{B3LYP exchange{correlation (xc) functional coupled to the Polarizable Embedding (PE) scheme (PE-CAM-B3LYP) in reproducing the solvatochromic shift of the lowest intense charge{transfer excitation in para...... the electric dipole moments in the gas phase and for 100 solvent congurations. We find that CAM-B3LYP overestimates the amount of charge separation inherent in the ground state and TDDFT/CAM-B3LYP drastically underestimates this amount in the excited charge-transfer state. As the errors in the solvatochromatic...... to benchmark results of TDDFT calculations with CAM-B3LYP for intramolecular charge{transfer excitations in molecular systems similar to pNA against higher{level ab initio wave function methods, like, e.g., CCSD, prior to their use. Using the calculated change in dipole moment upon excitation as a measure... 19. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme International Nuclear Information System (INIS) Theophilou, Iris; Tassi, M.; Thanos, S. 2014-01-01 Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations 20. State-selective charge transfer cross sections for light ion impact of atomic hydrogen Energy Technology Data Exchange (ETDEWEB) Schultz, D. R. [University of North Texas; Stancil, Phillip C. [University of Georgia, Athens; Havener, C. C. [Oak Ridge National Laboratory (ORNL) 2015-01-01 Owing to the utility of diagnosing plasma properties such as impurity concentration and spatial distribution, and plasma temperature and rotation, by detection of photon emission following capture of electrons from atomic hydrogen to excited states of multiply charged ions, new calculations of state-selective charge transfer involving light ions have been carried out using the atomic orbital close-coupling and the classical trajectory Monte Carlo methods. By comparing these with results of other approaches applicable in a lower impact energy regime, and by benchmarking them using key experimental data, knowledge of the cross sections can be made available across the range parameters needed by fusion plasma diagnostics. 1. Fermi level alignment in molecular nanojunctions and its relation to charge transfer DEFF Research Database (Denmark) Stadler, Robert; Jacobsen, Karsten Wedel 2006-01-01 The alignment of the Fermi level of a metal electrode within the gap of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a molecule is a key quantity in molecular electronics, which can vary the electron transparency of a single-molecule junction...... by orders of magnitude. We present a quantitative analysis of the relation between this level alignment (which can be estimated from charging free molecules) and charge transfer for bipyridine and biphenyl dithiolate (BPDT) molecules attached to gold leads based on density functional theory calculations...... end of the gap in the transmission function for bipyridine and at its lower end for BPDT.... 2. Molecular control of photoexcited charge transfer and recombination at a quaterthiophene/zinc oxide interface International Nuclear Information System (INIS) Mou Weiwei; Nakano, Aiichiro; Ohmura, Satoshi; Shimojo, Fuyuki 2012-01-01 Nonadiabatic quantum molecular dynamics simulations are performed to study photoexcited charge transfer (CT) and charge recombination (CR) at an interface between a conjugated oligomer donor, quaterthiophene (QT), and an inorganic acceptor (ZnO). Simulations reveal a detrimental effect of static disorder in QT conformation on the efficiency of hybrid QT/ZnO solar cells due to increased CR. On the contrary, dynamic disorder (i.e., fluctuation of carbon-hydrogen bonds in QT) is essential for high efficiency by assisting CT. The separate controllability of CT and CR at the molecular level has impacts on molecular design for efficient solar cells and explains recent experimental observations. 3. Energy and charge transfer dynamics between Alq3 and CdSeS nanocrystals. Science.gov (United States) Zhang, Shuping; Liu, Yuqiang; Yang, Yanqiang 2010-03-01 The photoluminescence properties of the blend films consisting of organic small molecules and nanocrystals (NCs)--Alq3 and CdSeS NCs--were studied by steady-state and time-resolved photoluminescence (PL) spectroscopy with different excited wavelengths. Both the fluorescence intensity and lifetime are intensively dependent on the NC concentration. The detailed analysis of experiment data proves that Forster energy transfer from the Alq3 to the NCs exists simultaneously with the charge transfer and both compete with each other in the blend films. 4. Temperature-dependent kinetics of charge transfer, hydrogen-atom transfer, and hydrogen-atom expulsion in the reaction of CO+ with CH4 and CD4. Science.gov (United States) Melko, Joshua J; Ard, Shaun G; Johnson, Ryan S; Shuman, Nicholas S; Guo, Hua; Viggiano, Albert A 2014-09-18 We have determined the rate constants and branching ratios for the reactions of CO(+) with CH4 and CD4 in a variable-temperature selected ion flow tube. We find that the rate constants are collisional for all temperatures measured (193-700 K for CH4 and 193-500 K for CD4). For the CH4 reaction, three product channels are identified, which include charge transfer (CH4(+) + CO), H-atom transfer (HCO(+) + CH3), and H-atom expulsion (CH3CO(+) + H). H-atom transfer is slightly preferred to charge transfer at low temperature, with the charge-transfer product increasing in contribution as the temperature is increased (H-atom expulsion is a minor product for all temperatures). Analogous products are identified for the CD4 reaction. Density functional calculations on the CO(+) + CH4 reaction were also conducted, revealing that the relative temperature dependences of the charge-transfer and H-atom transfer pathways are consistent with an initial charge transfer followed by proton transfer. 5. Dependence of charge transfer phenomena during solid-air two-phase flow on particle disperser Science.gov (United States) Tanoue, Ken-ichiro; Suedomi, Yuuki; Honda, Hirotaka; Furutani, Satoshi; Nishimura, Tatsuo; Masuda, Hiroaki 2012-12-01 An experimental investigation of the tribo-electrification of particles has been conducted during solid-air two-phase turbulent flow. The current induced in a metal plate by the impact of polymethylmethacrylate (PMMA) particles in a high-speed air flow was measured for two different plate materials. The results indicated that the contact potential difference between the particles and a stainless steel plate was positive, while for a nickel plate it was negative. These results agreed with theoretical contact charge transfer even if not only the particle size but also the kind of metal plate was changed. The specific charge of the PMMA particles during solid-air two-phase flow using an ejector, a stainless steel branch pipe, and a stainless steel straight pipe was measured using a Faraday cage. Although the charge was negative in the ejector, the particles had a positive specific charge at the outlet of the branch pipe, and this positive charge increased in the straight pipe. The charge decay along the flow direction could be reproduced by the charging and relaxation theory. However, the proportional coefficients in the theory changed with the particle size and air velocity. Therefore, an unexpected charge transfer occurred between the ejector and the branch pipe, which could not be explained solely by the contact potential difference. In the ejector, an electrical current in air might have been produced by self-discharge of particles with excess charge between the nickel diffuser in the ejector and the stainless steel nozzle or the stainless steel pipe due to a reversal in the contact potential difference between the PMMA and the stainless steel. The sign of the current depended on the particle size, possibly because the position where the particles impacted depended on their size. When dual coaxial glass pipes were used as a particle disperser, the specific charge of the PMMA particles became more positive along the particle flow direction due to the contact 6. Photodissociation and charge transfer dynamics of negative ions studied with femtosecond photoelectron spectroscopy Energy Technology Data Exchange (ETDEWEB) Zanni, Martin Thomas [Univ. of California, Berkeley, CA (United States) 1999-12-01 This dissertation presents studies aimed at understanding the potential energy surfaces and dynamics of isolated negative ions, and the effects of solvent on each. Although negative ions play important roles in atmospheric and solution phase chemistry, to a large extent the ground and excited state potential energy surfaces of gas phase negative ions are poorly characterized, and solvent effects even less well understood. In an effort to fill this gap, the author's coworkers and the author have developed a new technique, anion femtosecond photoelectron spectroscopy, and applied it to gas phase photodissociation and charge transfer processes. Studies are presented that (1) characterize the ground and excited states of isolated and clustered anions, (2) monitor the photodissociation dynamics of isolated and clustered anions, and (3) explore the charge-transfer-to-solvent states of atomic iodide clustered with polar and non-polar solvents. 7. Bands dispersion and charge transfer in β-BeH2 Science.gov (United States) Trivedi, D. K.; Galav, K. L.; Joshi, K. B. 2018-04-01 Predictive capabilities of ab-initio method are utilised to explore bands dispersion and charge transfer in β-BeH2. Investigations are carried out using the linear combination of atomic orbitals method at the level of density functional theory. The crystal structure and related parameters are settled by coupling total energy calculations with the Murnaghan equation of state. Electronic bands dispersion from PBE-GGA is reported. The PBE-GGA, and PBE0 hybrid functional, show that β-BeH2 is a direct gap semiconductor with 1.18 and 2.40 eV band gap. The band gap slowly decreases with pressure and beyond l00 GPa overlap of conduction and valence bands at the r point is observed. Charge transfer is studied by means of Mullikan population analysis. 8. Charge transfer complex in diketopyrrolopyrrole polymers and fullerene blends: Implication for organic solar cell efficiency Science.gov (United States) Moghe, D.; Yu, P.; Kanimozhi, C.; Patil, S.; Guha, S. 2012-02-01 Copolymers based on diketopyrrolopyrrole (DPP) have recently gained potential in organic photovoltaics. When blended with another acceptor such as PCBM, intermolecular charge transfer occurs which may result in the formation of charge transfer (CT) states. We present here the spectral photocurrent characteristics of two donor-acceptor DPP based copolymers, PDPP-BBT and TDPP-BBT, blended with PCBM to identify the CT states. The spectral photocurrent measured using Fourier-transform photocurrent spectroscopy (FTPS) and monochromatic photocurrent (PC) methods are compared with P3HT:PCBM, where the CT state is well known. PDPP-BBT:PCBM shows a stable CT state while TDPP-BBT does not. Our analysis shows that the larger singlet state energy difference between TDPP-BBT and PCBM along with the lower optical gap of TDPP-BBT obliterates the formation of a midgap CT state resulting in an enhanced photovoltaic efficiency over PDPP-BBT:PCBM. 9. Study on charge transfer reaction of several organic molecules with accelerated rare gas ions International Nuclear Information System (INIS) Takahasi, Makoto; Okuda, Sachiko; Arai, Eiichi; Ichinose, Akira; Takakubo, Masaaki. 1984-01-01 Observing the charge transfer mass spectra of ethylbenzene, cyclobutane and methanol in Ar and Xe ion impacts, we investigated the dependence of the secondary ion peak intensities (normalized to primary ion current and target pressure) on the translational energy of primary ions (0-3500 eV).In the case of ethylbenzene, several maxima of the secondary i on peak intensities were observed in Ar and Xe ion impacts. The correlation between the maxima and the primary ion energy was examined in terms of near adiabatic theory of Massey. Supplementary studies on the energy distribution of primary ion, charge transfer cross section between methanol and Xe ion, and final product analysis in rare gas ion irradiation on cyclobutane were described. (author) 10. Oxidation and Metal-Insertion in Molybdenite Surfaces: Evaluation of Charge-Transfer Mechanisms and Dynamics Energy Technology Data Exchange (ETDEWEB) Ramana, Chintalapalle V.; Becker, U.; Shutthanandan, V.; Julien, C. M. 2008-06-05 Molybdenum sulfide (MoS2), an important representative member of the layered transition-metal dichalcogenides, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and industrial science and technology. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. On the other hand understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is quite important to utilize these minerals in technological applications. Furthermore, such a detailed investigation of thermal oxidation behavior and intercalation process will provide a basis to further explore and model the mechanism of adsorption of metal ions on to geomedia. Therefore, the present work was performed to understand the oxidation and intercalation processes of molybdenite surfaces. The results obtained, using a wide variety of analytical techniques, are presented and discussed in this paper. 11. Photodissociation and charge transfer dynamics of negative ions studied with femtosecond photoelectron spectroscopy International Nuclear Information System (INIS) Zanni, Martin T. 1999-01-01 This dissertation presents studies aimed at understanding the potential energy surfaces and dynamics of isolated negative ions, and the effects of solvent on each. Although negative ions play important roles in atmospheric and solution phase chemistry, to a large extent the ground and excited state potential energy surfaces of gas phase negative ions are poorly characterized, and solvent effects even less well understood. In an effort to fill this gap, the author's coworkers and the author have developed a new technique, anion femtosecond photoelectron spectroscopy, and applied it to gas phase photodissociation and charge transfer processes. Studies are presented that (1) characterize the ground and excited states of isolated and clustered anions, (2) monitor the photodissociation dynamics of isolated and clustered anions, and (3) explore the charge-transfer-to-solvent states of atomic iodide clustered with polar and non-polar solvents 12. Highly mobile charge-transfer excitons in two-dimensional WS2/tetracene heterostructures Science.gov (United States) Zhu, Tong; Yuan, Long; Zhao, Yan; Zhou, Mingwei; Wan, Yan; Mei, Jianguo; Huang, Libai 2018-01-01 Charge-transfer (CT) excitons at heterointerfaces play a critical role in light to electricity conversion using organic and nanostructured materials. However, how CT excitons migrate at these interfaces is poorly understood. We investigate the formation and transport of CT excitons in two-dimensional WS2/tetracene van der Waals heterostructures. Electron and hole transfer occurs on the time scale of a few picoseconds, and emission of interlayer CT excitons with a binding energy of ~0.3 eV has been observed. Transport of the CT excitons is directly measured by transient absorption microscopy, revealing coexistence of delocalized and localized states. Trapping-detrapping dynamics between the delocalized and localized states leads to stretched-exponential photoluminescence decay with an average lifetime of ~2 ns. The delocalized CT excitons are remarkably mobile with a diffusion constant of ~1 cm2 s−1. These highly mobile CT excitons could have important implications in achieving efficient charge separation. PMID:29340303 13. Impact of speciation on the electron charge transfer properties of nanodiamond drug carriers. Science.gov (United States) Sun, Baichuan; Barnard, Amanda S 2016-08-07 Unpassivated diamond nanoparticles (bucky-diamonds) exhibit a unique surface reconstruction involving graphitization of certain crystal facets, giving rise to hybrid core-shell particles containing both aromatic and aliphatic carbon. Considerable effort is directed toward eliminating the aromatic shell, but persistent graphitization of subsequent subsurface-layers makes perdurable purification a challenge. In this study we use some simple statistical methods, in combination with electronic structure simulations, to predict the impact of different fractions of aromatic and aliphatic carbon on the charge transfer properties of the ensembles of bucky-diamonds. By predicting quality factors for a variety of cases, we find that perfect purification is not necessary to preserve selectivity, and there is a clear motivation for purifying samples to improve the sensitivity of charge transfer reactions. This may prove useful in designing drug delivery systems where the release of (selected) drugs needs to be sensitive to specific conditions at the point of delivery. 14. Muon transfer from muonic hydrogen to heavier atoms; Transfert de charge muonique Energy Technology Data Exchange (ETDEWEB) Dupays, A 2004-06-01 This work concerns muon transfer from muonic hydrogen to heavier atoms. Recently, a method of measurement of the hyperfine structure of ground-state muonic hydrogen based on the collision energy dependence of the muon transfer rate to oxygen has been proposed. This proposal is based on measurements which where performed at the Paul Scherrer Institute in the early nineties which indicate that the muon transfer from muonic hydrogen to oxygen increases by a factor of 4 going from thermal to 0.12 eV energies. The motivation of our calculations was to confirm this behaviour. To study the collision energy dependence of the muon transfer rate, we have used a time-independent close-coupling method. We have set up an hyperspherical elliptic formalism valid for nonzero total angular momentum which allows accurate computations of state-to-state reactive and charge exchange processes. We have applied this formalism to muon-transfer process to oxygen and neon. The comparison with experimental results is in both cases excellent. Finally, the neon transfer rate dependence with energy suggests to use neon instead of oxygen to perform a measurement of the hyperfine structure of muonic hydrogen. The results of accurate calculations of the muon transfer rates from muonic protium and deuterium atoms to nitrogen, oxygen and neon are also reported. Very good agreement with measured rates is obtained and for the three systems, the isotopic effect is perfectly reproduced. (author) 15. Oxygen-assisted charge transfer between ZnO quantum dots and graphene. Science.gov (United States) Guo, Wenhao; Xu, Shuigang; Wu, Zefei; Wang, Ning; Loy, M M T; Du, Shengwang 2013-09-23 Efficient charge transfer between ZnO quantum dots (QDs) and graphene is demonstrated by decorating ZnO QDs on top of graphene, with the assistance of oxygen molecules from the air. The electrical response of the device to UV light is greatly enhanced, and a photoconductive gain of up to 10(7) can be obtained. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 16. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics Directory of Open Access Journals (Sweden) Shutthanandan V 2008-06-01 Full Text Available Abstract Molybdenum disulfide (MoS2, a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia. The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM, scanning electron microscopy (SEM, transmission electron microscopy (TEM, Rutherford backscattering spectrometry (RBS, and nuclear reaction analysis (NRA. Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400°C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and 17. Oxidation and metal-insertion in molybdenite surfaces: evaluation of charge-transfer mechanisms and dynamics. Science.gov (United States) Ramana, C V; Becker, U; Shutthanandan, V; Julien, C M 2008-06-05 Molybdenum disulfide (MoS2), a layered transition-metal dichalcogenide, has been of special importance to the research community of geochemistry, materials and environmental chemistry, and geotechnical engineering. Understanding the oxidation behavior and charge-transfer mechanisms in MoS2 is important to gain better insight into the degradation of this mineral in the environment. In addition, understanding the insertion of metals into molybdenite and evaluation of charge-transfer mechanism and dynamics is important to utilize these minerals in technological applications. Furthermore, a detailed investigation of thermal oxidation behavior and metal-insertion will provide a basis to further explore and model the mechanism of adsorption of metal ions onto geomedia.The present work was performed to understand thermal oxidation and metal-insertion processes of molybdenite surfaces. The analysis was performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA).Structural studies using SEM and TEM indicate the local-disordering of the structure as a result of charge-transfer process between the inserted lithium and the molybdenite layer. Selected area electron diffraction measurements indicate the large variations in the diffusivity of lithium confirming that the charge-transfer is different along and perpendicular to the layers in molybdenite. Thermal heating of molybenite surface in air at 400 degrees C induces surface oxidation, which is slow during the first hour of heating and then increases significantly. The SEM results indicate that the crystals formed on the molybdenite surface as a result of thermal oxidation exhibit regular thin-elongated shape. The average size and density of the crystals on the surface is dependent on the time of annealing; smaller size and high density during the first one-hour and significant 18. Lifetimes of partial charge transfer exciplexes of 9-cyanophenanthrene and 9-cyanoanthracene OpenAIRE Dolotova, Elena; Dogadkin, Denis; Soboleva, Irina; Kuzmin, Michael; Nicolet, Olivier; Vauthey, Eric 2003-01-01 The fluorescence decays of several exciplexes with partial charge transfer have been investigated in solvents of various polarity. The measured lifetimes are found to be in reasonable agreement with the activation enthalpy and entropy of exciplex decay obtained earlier from the temperature dependence of the exciplex emission quantum yields. For exciplexes with 9-cyanophenanthrene substantial contribution of the higher local excited state into the exciplex electronic structure is found and bor... 19. Imidazole as a parent π-conjugated backbone in charge-transfer chromophores Directory of Open Access Journals (Sweden) Jiří Kulhánek 2012-01-01 Full Text Available Research activities in the field of imidazole-derived push–pull systems featuring intramolecular charge transfer (ICT are reviewed. Design, synthetic pathways, linear and nonlinear optical properties, electrochemistry, structure–property relationships, and the prospective application of such D-π-A organic materials are described. This review focuses on Y-shaped imidazoles, bi- and diimidazoles, benzimidazoles, bis(benzimidazoles, imidazole-4,5-dicarbonitriles, and imidazole-derived chromophores chemically bound to a polymer chain. 20. Development and capital investment tasks involved in the production of charge transfer equipment International Nuclear Information System (INIS) Simon, Sandor 1983-01-01 Stringent requirements had to be considered in the course of the production development of charge transfer equipment. The production of structures demanding extremely high endurance was based on extensive co-operation. Special alloys were needed for parts and bearings, special heat-treatment was required at certain sections for large dimensions etc. Appropriate mashine stock, assembly and test hall have been built for assembling and testing the equipment with both 440 and 100 MW.(Sz.J.) 1. Charge transfer collisions of Si^3+ with H at low energies Science.gov (United States) Joseph, D. C.; Gu, J. P.; Saha, B. C. 2009-11-01 Charge transfer of positively charged ions with atomic hydrogen is important not only in magnetically confined plasmas between impurity ions and H atoms from the chamber walls influences the overall ionization balance and effects the plasma cooling but also in astrophysics, where it plays a key role in determining the properties of the observed gas. It also provides a recombination mechanism for multiply charged ions in X-ray ionized astronomical environments. We report an investigation using the molecular-orbital close-coupling (MOCC) method, both quantum mechanically and semi-classically, in the adiabatic representation. Ab initio adiabatic potentials and coupling matrix elements--radial and angular--are calculated using the MRD-CI method. Comparison of our results with other theoretical as well as experimental findings will be discussed. 2. Computational models of an inductive power transfer system for electric vehicle battery charge Science.gov (United States) Anele, A. O.; Hamam, Y.; Chassagne, L.; Linares, J.; Alayli, Y.; Djouani, K. 2015-09-01 One of the issues to be solved for electric vehicles (EVs) to become a success is the technical solution of its charging system. In this paper, computational models of an inductive power transfer (IPT) system for EV battery charge are presented. Based on the fundamental principles behind IPT systems, 3 kW single phase and 22 kW three phase IPT systems for Renault ZOE are designed in MATLAB/Simulink. The results obtained based on the technical specifications of the lithium-ion battery and charger type of Renault ZOE show that the models are able to provide the total voltage required by the battery. Also, considering the charging time for each IPT model, they are capable of delivering the electricity needed to power the ZOE. In conclusion, this study shows that the designed computational IPT models may be employed as a support structure needed to effectively power any viable EV. 3. Computational models of an inductive power transfer system for electric vehicle battery charge International Nuclear Information System (INIS) Anele, A O; Hamam, Y; Djouani, K; Chassagne, L; Alayli, Y; Linares, J 2015-01-01 One of the issues to be solved for electric vehicles (EVs) to become a success is the technical solution of its charging system. In this paper, computational models of an inductive power transfer (IPT) system for EV battery charge are presented. Based on the fundamental principles behind IPT systems, 3 kW single phase and 22 kW three phase IPT systems for Renault ZOE are designed in MATLAB/Simulink. The results obtained based on the technical specifications of the lithium-ion battery and charger type of Renault ZOE show that the models are able to provide the total voltage required by the battery. Also, considering the charging time for each IPT model, they are capable of delivering the electricity needed to power the ZOE. In conclusion, this study shows that the designed computational IPT models may be employed as a support structure needed to effectively power any viable EV. (paper) 4. Charge-Transfer States in Organic Solar Cells: Understanding the Impact of Polarization, Delocalization, and Disorder KAUST Repository Zheng, Zilong 2017-05-08 We investigate the impact of electronic polarization, charge delocalization, and energetic disorder on the charge-transfer (CT) states formed at a planar C60/pentacene interface. The ability to examine large complexes containing up to seven pentacene molecules and three C60 molecules allows us to take explicitly into account the electronic polarization effects. These complexes are extracted from a bilayer architecture modeled by molecular dynamics simulations and evaluated by means of electronic-structure calculations based on long-range-separated functionals (ωB97XD and BNL) with optimized range-separation parameters. The energies of the lowest charge-transfer states derived for the large complexes are in very good agreement with the experimentally reported values. The average singlet-triplet energy splittings of the lowest CT states are calculated not to exceed 10 meV. The rates of geminate recombination as well as of dissociation of the triplet excitons are also evaluated. In line with experiment, our results indicate that the pentacene triplet excitons generated through singlet fission can dissociate into separated charges on a picosecond time scale, despite the fact that their energy in C60/pentacene heterojunctions is slightly lower than the energies of the lowest CT triplet states. 5. Charge transfer through DNA/DNA duplexes and DNA/RNA hybrids: complex theoretical and experimental studies. Science.gov (United States) Kratochvílová, Irena; Vala, Martin; Weiter, Martin; Špérová, Miroslava; Schneider, Bohdan; Páv, Ondřej; Šebera, Jakub; Rosenberg, Ivan; Sychrovský, Vladimír 2013-01-01 Oligonucleotides conduct electric charge via various mechanisms and their characterization and understanding is a very important and complicated task. In this work, experimental (temperature dependent steady state fluorescence spectroscopy, time-resolved fluorescence spectroscopy) and theoretical (Density Functional Theory) approaches were combined to study charge transfer processes in short DNA/DNA and RNA/DNA duplexes with virtually equivalent sequences. The experimental results were consistent with the theoretical model - the delocalized nature of HOMO orbitals and holes, base stacking, electronic coupling and conformational flexibility formed the conditions for more effective short distance charge transfer processes in RNA/DNA hybrids. RNA/DNA and DNA/DNA charge transfer properties were strongly connected with temperature affected structural changes of molecular systems - charge transfer could be used as a probe of even tiny changes of molecular structures and settings. © 2013. Published by Elsevier B.V. All rights reserved. 6. Density functional theory for the description of charge-transfer processes at TTF/TCNQ interfaces KAUST Repository Van Regemorter, Tanguy; Guillaume, Maxime; Sini, Gjergji; Sears, John S.; Geskin, Victor; Bré das, Jean-Luc; Beljonne, David; Cornil, Jé rô me 2012-01-01 In the field of organic electronics, a central issue is to assess how the frontier electronic levels of two adjacent organic layers align with respect to one another at the interface. This alignment can be driven by the presence of a partial charge transfer and the formation of an interface dipole; it plays a key role for instance in determining the rates of exciton dissociation or exciton formation in organic solar cells or light-emitting diodes, respectively. Reliably modeling the processes taking place at these interfaces remains a challenge for the computational chemistry community. Here, we review our recent theoretical work on the influence of the choice of density functional theory (DFT) methodology on the description of the charge-transfer character in the ground state of TTF/ TCNQ model complexes and interfaces. Starting with the electronic properties of the isolated TTF and TCNQ molecules and then considering the charge transfer and resulting interface dipole in TTF/TCNQ donor-acceptor stacks and bilayers, we examine the impact of the choice of DFT functional in describing the interfacial electronic structure. Finally, we employ computations based on periodic boundary conditions to highlight the impact of depolarization effects on the interfacial dipole moment. © Springer-Verlag 2012. 7. Development of highly accurate approximate scheme for computing the charge transfer integral Energy Technology Data Exchange (ETDEWEB) Pershin, Anton; Szalay, Péter G. [Laboratory for Theoretical Chemistry, Institute of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest (Hungary) 2015-08-21 The charge transfer integral is a key parameter required by various theoretical models to describe charge transport properties, e.g., in organic semiconductors. The accuracy of this important property depends on several factors, which include the level of electronic structure theory and internal simplifications of the applied formalism. The goal of this paper is to identify the performance of various approximate approaches of the latter category, while using the high level equation-of-motion coupled cluster theory for the electronic structure. The calculations have been performed on the ethylene dimer as one of the simplest model systems. By studying different spatial perturbations, it was shown that while both energy split in dimer and fragment charge difference methods are equivalent with the exact formulation for symmetrical displacements, they are less efficient when describing transfer integral along the asymmetric alteration coordinate. Since the “exact” scheme was found computationally expensive, we examine the possibility to obtain the asymmetric fluctuation of the transfer integral by a Taylor expansion along the coordinate space. By exploring the efficiency of this novel approach, we show that the Taylor expansion scheme represents an attractive alternative to the “exact” calculations due to a substantial reduction of computational costs, when a considerably large region of the potential energy surface is of interest. Moreover, we show that the Taylor expansion scheme, irrespective of the dimer symmetry, is very accurate for the entire range of geometry fluctuations that cover the space the molecule accesses at room temperature. 8. A two-dimensional position sensitive gas chamber with scanned charge transfer readout Energy Technology Data Exchange (ETDEWEB) Gomez, F. E-mail: faustgr@usc.es; Iglesias, A.; Lobato, R.; Mosquera, J.; Pardo, J.; Pena, J.; Pazos, A.; Pombar, M.; Rodriguez, A 2003-10-21 We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 {mu}m thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8x8 cm{sup 2} with a pixel size of 1.27x1.27 mm{sup 2}. Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring. 9. Overcoming the Cut-Off Charge Transfer Bandgaps at the PbS Quantum Dot Interface KAUST Repository El-Ballouli, Ala'a O. 2015-11-17 Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD-based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron-accepting unit with a new driving force for CT is urgently needed to harvest the light from large-sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time-resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD-based solar cells that make the best use of the diverse photons making up the Sun\\'s broad irradiance spectrum. 10. Charge transfer in photorechargeable composite films of TiO2 and polyaniline Science.gov (United States) Nomiyama, Teruaki; Sasabe, Kenichi; Sakamoto, Kenta; Horie, Yuji 2015-07-01 A photorechargeable battery (PRB) is a photovoltaic device having an energy storage function in a single cell. The photoactive electrode of PRB is a bilayer film consisting of bare porous TiO2 and a TiO2-polyaniline (PANi) mixture that work as a photovoltaic current generator and an electrochemical energy storage by ion dedoping, respectively. To study the charge transfer between TiO2 and PANi, the photorechargeable quantum efficiency QE ([electron count on discharge]/[incident photon count on photocharge]) was measured by varying the thickness LS of the TiO2-PANi mixture. The quantum efficiency QEuv for UV photons had a maximum of ˜7% at LS ˜ 7 µm. The time constant τTP for the charge transfer was about 10-1 s, which was longer ten times or more than the lifetime of excited electrons within TiO2. These facts reveal that the main rate-limiting factor in the photocharging process is the charge transfer between TiO2 and PANi. 11. Tuning electronic properties of graphene nanoflake polyaromatic hydrocarbon through molecular charge-transfer interactions Science.gov (United States) Sharma, Vaishali; Dabhi, Shweta D.; Shinde, Satyam; Jha, Prafulla K. 2018-05-01 By means of first principles calculation we have tuned the electronic properties of graphene nanoflake polyaromatic hydrocarbon via molecular charge transfer. Acceptor/donor Tetracyanoquinodimethane (TCNQ) and Tetrathiafulvalene (TTF) organic molecules are adsorbed on polyaromatic hydrocarbons (PAH) in order to introduce the charge transfer. The substrate's n- or p- type nature depends on the accepting/donating behavior of dopant molecules. Two different classes of PAH (extended form of triangulene) namely Bow-tie graphene nanoflake (BTGNF) and triangular zigzag graphene nanoflake (TZGNF). It is revealed that all the TCNQ and TTF modified graphene nanoflakes exhibit significant changes in HOMO-LUMO gap in range from 0.58 eV to 0.64 eV and 0.01 eV to 0.05 eV respectively. The adsorption energies are in the range of -0.05 kcal/mol to -2.6 kcal/mol. The change in work function is also calculated and discussed, the maximum charge transfer is for TCNQ adsorbed BTGNF. These alluring findings in the tuning of electronic properties will be advantageous for promoting graphene nanoflake polyaromatic hydrocarbon for their applications in electronic devices. 12. Density functional theory for the description of charge-transfer processes at TTF/TCNQ interfaces KAUST Repository Van Regemorter, Tanguy 2012-09-15 In the field of organic electronics, a central issue is to assess how the frontier electronic levels of two adjacent organic layers align with respect to one another at the interface. This alignment can be driven by the presence of a partial charge transfer and the formation of an interface dipole; it plays a key role for instance in determining the rates of exciton dissociation or exciton formation in organic solar cells or light-emitting diodes, respectively. Reliably modeling the processes taking place at these interfaces remains a challenge for the computational chemistry community. Here, we review our recent theoretical work on the influence of the choice of density functional theory (DFT) methodology on the description of the charge-transfer character in the ground state of TTF/ TCNQ model complexes and interfaces. Starting with the electronic properties of the isolated TTF and TCNQ molecules and then considering the charge transfer and resulting interface dipole in TTF/TCNQ donor-acceptor stacks and bilayers, we examine the impact of the choice of DFT functional in describing the interfacial electronic structure. Finally, we employ computations based on periodic boundary conditions to highlight the impact of depolarization effects on the interfacial dipole moment. © Springer-Verlag 2012. 13. Models of charge transport and transfer in molecular switch tunnel junctions of bistable catenanes and rotaxanes International Nuclear Information System (INIS) Flood, Amar H.; Wong, Eric W.; Stoddart, J. Fraser 2006-01-01 The processes by which charge transfer can occur play a foundational role in molecular electronics. Here we consider simplified models of the transfer processes that could be present in bistable molecular switch tunnel junction (MSTJ) devices during one complete cycle of the device from its low- to high- and back to low-conductance state. The bistable molecular switches, which are composed of a monolayer of either switchable catenanes or rotaxanes, exist in either a ground-state co-conformation or a metastable one in which the conduction properties of the two co-conformations, when measured at small biases (+0.1 V), are significantly different irrespective of whether transport is dominated by tunneling or hopping. The voltage-driven generation (±2 V) of molecule-based redox states, which are sufficiently long-lived to allow the relative mechanical movements necessary to switch between the two co-conformations, rely upon unequal charge transfer rates on to and/or off of the molecules. Surface-enhanced Raman spectroscopy has been used to image the ground state of the bistable rotaxane in MSTJ-like devices. Consideration of these models provide new ways of looking at molecular electronic devices that rely, not only on nanoscale charge-transport, but also upon the bustling world of molecular motion in mechanically interlocked bistable molecules 14. Photoinduced charge and energy transfer in dye-doped conjugated polymers International Nuclear Information System (INIS) Veldman, Dirk; Bastiaansen, Jolanda J.A.M.; Langeveld-Voss, Bea M.W.; Sweelssen, Joergen; Koetse, Marc M.; Meskers, Stefan C.J.; Janssen, Rene A.J. 2006-01-01 Conjugated polymer-molecular dye blends of MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]) and PF1CVTP (poly[9,9-dioctylfluorene-2,7-diyl-alt-2,5-bis(2-thienyl-1-cyanovinyl) -1-(3',7= '-dimethyloctyloxy)-4-methoxybenzene-5'',5''-diyl]) with three dipyrrometheneboron difluoride (bodipy) dyes were studied by (time-resolved) fluorescence and photoinduced absorption spectroscopy to determine quantitatively the relation between the electronic HOMO and LUMO levels and the occurrence of energy or charge transfer after optical excitation. We find that for MDMO-PPV photoinduced charge transfer to the dyes occurs, while photoexcitation of PF1CVTP exclusively results in energy transfer. The differences can be rationalized by assuming that the energy of the charge separated state is 0.33-0.45 eV higher than the energy determined from oxidation and reduction potentials of donor and acceptor, respectively. This provides an important design rule to identify appropriate materials for polymer solar cells that can have a high open-circuit voltage 15. Charge-transfer complexes and their role in exciplex emission and near-infrared photovoltaics. Science.gov (United States) Ng, Tsz-Wai; Lo, Ming-Fai; Fung, Man-Keung; Zhang, Wen-Jun; Lee, Chun-Sing 2014-08-20 Charge transfer and interactions at organic heterojunctions (OHJs) are known to have critical influences on various properties of organic electronic devices. In this Research News article, a short review is given from the electronic viewpoint on how the local molecular interactions and interfacial energetics at P/N OHJs contribute to the recombination/dissociation of electron-hole pairs. Very often, the P-type materials donate electrons to the N-type materials, giving rise to charge-transfer complexes (CTCs) with a P(δ+) -N(δ-) configuration. A recently observed opposite charge-transfer direction in OHJs is also discussed (i.e., N-type material donates electrons to P-type material to form P(δ-) -N(δ+) ). Recent studies on the electronic structures of CTC-forming material pairs are also summarized. The formation of P(δ-) -N(δ+) -type CTCs and their correlations with exciplex emission are examined. Furthermore, the potential applications of CTCs in NIR photovoltaic devices are reviewed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 16. Microchip-calorimetry of organic charge transfer complex which shows superconductivity at low temperatures Energy Technology Data Exchange (ETDEWEB) Muraoka, Yuki [Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043 (Japan); Yamashita, Satoshi [RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Yamamoto, Takashi [Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043 (Japan); Nakazawa, Yasuhiro, E-mail: nakazawa@chem.sci.osaka-u.ac.jp [Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043 (Japan); Institute for Molecular Science, Nishigonaka 38, Myodaiji, Okazaki 444-8585 (Japan) 2012-03-20 Highlights: Black-Right-Pointing-Pointer Organic charge transfer salt of {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br shows superconductivity. Black-Right-Pointing-Pointer We succeeded to detect thermal anomaly microchip device TCG3880. Black-Right-Pointing-Pointer Development details of the calorimeter and the detection system is presented. Black-Right-Pointing-Pointer The magnetic fields dependence shows typical character of layered superconductor. - Abstract: We carried out thermodynamic measurements of organic charge transfer complex of {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene by TCG3880 chip device in order to examine capability of the chip calorimeter at low temperature region and under magnetic fields. TCG3880 chip is mounted on a {sup 3}He cryostat available in combination with a superconductive magnet up to 7 T. Thermal anomalies related to the glass-like freezing of ethylene groups of BEDT-TTF molecules and the superconductive transition were observed. A frequency dependence of the thermal anomaly of the glass formation and a magnetic fields dependence of the thermal anomaly of the superconductive transition are reported. The results presented in this work demonstrate that the TCG3880 is quite useful for thermodynamic investigations of the organic charge transfer complex with much reduced sample quantity as compared with those of relaxation and adiabatic calorimetry. 17. The charge transfer characteristic of tetraphenylporphyrin iron chloride Langmuir–Blodgett films International Nuclear Information System (INIS) Du, Y.; Li, Z.H.; Qi, P.; Wang, F.; Liu, D. 2013-01-01 The charge transfer characteristic of tetraphenylporphyrin iron (III) chloride (FeP) Langmuir–Blodgett (LB) films on the surface of the ITO glass electrode was reported. When the cyclic voltammetry (CV) scanning was running, the charge transfer characteristic was controlled by the oxidation–reduction process of Fe(III)/Fe(II). The charge transfer characteristic was related to the following factors: the cross-sectional area, relative to the electrode, of FeP as the electron donor (or acceptor). The greater the cross-sectional area of the aggregation of FeP as the electron donor (or acceptor) was, the larger the number of the donated (or accepted) electrons was. The projected area of the cross-section on the ITO electrode. The greater the projected area was, the larger the number of the donated (or accepted) electrons was. The distance between the center of the electron donor (or acceptor) of FeP and the surface of ITO electrode. The smaller the distance was, the greater the rate of donating (or accepting) electrons was. The monolayer coverage, which formed because of the FeP lying on the ITO surface in the form of the monomer and aggregate, was more sensitive to detect oxygen 18. Overcoming the Cut-Off Charge Transfer Bandgaps at the PbS Quantum Dot Interface KAUST Repository El-Ballouli, Ala'a O.; Alarousu, Erkki; Kirmani, Ahmad R.; Amassian, Aram; Bakr, Osman; Mohammed, Omar F. 2015-01-01 Light harvesting from large size of semiconductor PbS quantum dots (QDs) with a bandgap of less than 1 eV is one of the greatest challenges precluding the development of PbS QD-based solar cells because the interfacial charge transfer (CT) from such QDs to the most commonly used electron acceptor materials is very inefficient, if it occurs at all. Thus, an alternative electron-accepting unit with a new driving force for CT is urgently needed to harvest the light from large-sized PbS QDs. Here, a cationic porphyrin is utilized as a new electron acceptor unit with unique features that bring the donor–acceptor components into close molecular proximity, allowing ultrafast and efficient electron transfer for QDs of all sizes, as inferred from the drastic photoluminescence quenching and the ultrafast formation of the porphyrin anionic species. The time-resolved results clearly demonstrate the possibility of modulating the electron transfer process between PbS QDs and porphyrin moieties not only by the size quantization effect but also by the interfacial electrostatic interaction between the positively charged porphyrin and the negatively charged QDs. This approach provides a new pathway for engineering QD-based solar cells that make the best use of the diverse photons making up the Sun's broad irradiance spectrum. 19. A novel transferable individual tree crown delineation model based on Fishing Net Dragging and boundary classification Science.gov (United States) Liu, Tao; Im, Jungho; Quackenbush, Lindi J. 2015-12-01 This study provides a novel approach to individual tree crown delineation (ITCD) using airborne Light Detection and Ranging (LiDAR) data in dense natural forests using two main steps: crown boundary refinement based on a proposed Fishing Net Dragging (FiND) method, and segment merging based on boundary classification. FiND starts with approximate tree crown boundaries derived using a traditional watershed method with Gaussian filtering and refines these boundaries using an algorithm that mimics how a fisherman drags a fishing net. Random forest machine learning is then used to classify boundary segments into two classes: boundaries between trees and boundaries between branches that belong to a single tree. Three groups of LiDAR-derived features-two from the pseudo waveform generated along with crown boundaries and one from a canopy height model (CHM)-were used in the classification. The proposed ITCD approach was tested using LiDAR data collected over a mountainous region in the Adirondack Park, NY, USA. Overall accuracy of boundary classification was 82.4%. Features derived from the CHM were generally more important in the classification than the features extracted from the pseudo waveform. A comprehensive accuracy assessment scheme for ITCD was also introduced by considering both area of crown overlap and crown centroids. Accuracy assessment using this new scheme shows the proposed ITCD achieved 74% and 78% as overall accuracy, respectively, for deciduous and mixed forest. 20. Charge-transfer mobility and electrical conductivity of PANI as conjugated organic semiconductors. Science.gov (United States) Zhang, Yahong; Duan, Yuping; Song, Lulu; Zheng, Daoyuan; Zhang, Mingxing; Zhao, Guangjiu 2017-09-21 The intramolecular charge transfer properties of a phenyl-end-capped aniline tetramer (ANIH) and a chloro-substituted derivative (ANICl) as organic semiconductors were theoretically studied through the first-principles calculation based on the Marcus-Hush theory. The reorganization energies, intermolecular electronic couplings, angular resolution anisotropic mobilities, and density of states of the two crystals were evaluated. The calculated results demonstrate that both ANIH and ANICl crystals show the higher electron transfer mobilities than the hole-transfer mobilities, which means that the two crystals should prefer to function as n-type organic semiconductors. Furthermore, the angle dependence mobilities of the two crystals show remarkable anisotropic character. The maximum mobility μ max of ANIH and ANICl crystals is 1.3893 and 0.0272 cm 2 V -1 s -1 , which appear at the orientation angles near 176°/356° and 119°/299° of a conducting channel on the a-b reference plane. It is synthetically evaluated that the ANIH crystal possesses relatively lower reorganization energy, higher electronic coupling, and electron transfer mobility, which means that the ANIH crystal may be the more ideal candidate as a high performance n-type organic semiconductor material. The systematic theoretical studies on organic crystals should be conducive to evaluating the charge-transport properties and designing higher performance organic semiconductor materials. 1. Charge transfer dynamics from adsorbates to surfaces with single active electron and configuration interaction based approaches Energy Technology Data Exchange (ETDEWEB) Ramakrishnan, Raghunathan, E-mail: r.ramakrishnan@unibas.ch [Institute of Physical Chemistry, National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Nest, Mathias [Theoretische Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching (Germany) 2015-01-13 Highlights: • We model electron dynamics across cyano alkanethiolates attached to gold cluster. • We present electron transfer time scales from TD-DFT and TD-CI based simulations. • Both DFT and CI methods qualitatively predict the trend in time scales. • TD-CI predicts the experimental relative time scale very accurately. - Abstract: We employ wavepacket simulations based on many-body time-dependent configuration interaction (TD-CI), and single active electron theories, to predict the ultrafast molecule/metal electron transfer time scales, in cyano alkanethiolates bonded to model gold clusters. The initial states represent two excited states where a valence electron is promoted to one of the two virtual π{sup ∗} molecular orbitals localized on the cyanide fragment. The ratio of the two time scales indicate the efficiency of one charge transfer channel over the other. In both our one-and many-electron simulations, this ratio agree qualitatively with each other as well as with the previously reported experimental time scales (Blobner et al., 2012), measured for a macroscopic metal surface. We study the effect of cluster size and the description of electron correlation on the charge transfer process. 2. Charge transfer luminescence of Yb3+ ions in LiY1-xYbxP4O12 phosphates International Nuclear Information System (INIS) Stryganyuk, G; Zazubovich, S; Voloshinovskii, A; Pidzyrailo, M; Zimmerer, G; Peters, R; Petermann, K 2007-01-01 Spectral-kinetic studies have been performed for LiY 1-x Yb x P 4 O 12 (x = 0; 0.1; 0.9) phosphates at T = 8-320 K using synchrotron radiation for excitation within the 5-17 eV energy range. Mechanisms for the excitation of Yb 3+ charge transfer and f-f luminescence are discussed. The quasimolecular character of Yb 3+ charge transfer luminescence (CTL) is pointed out. The central Yb 2+ ion and hole delocalized over the surrounding ligands are proposed for consideration as a 'charge transfer cluster' (Yb 2+ CT cluster). Possible mechanisms of Yb 3+ CTL quenching are presumed 3. Layer-dependent surface potential of phosphorene and anisotropic/layer-dependent charge transfer in phosphorene-gold hybrid systems. Science.gov (United States) Xu, Renjing; Yang, Jiong; Zhu, Yi; Yan, Han; Pei, Jiajie; Myint, Ye Win; Zhang, Shuang; Lu, Yuerui 2016-01-07 The surface potential and the efficiency of interfacial charge transfer are extremely important for designing future semiconductor devices based on the emerging two-dimensional (2D) phosphorene. Here, we directly measured the strong layer-dependent surface potential of mono- and few-layered phosphorene on gold, which is consistent with the reported theoretical prediction. At the same time, we used an optical way photoluminescence (PL) spectroscopy to probe charge transfer in the phosphorene-gold hybrid system. We firstly observed highly anisotropic and layer-dependent PL quenching in the phosphorene-gold hybrid system, which is attributed to the highly anisotropic/layer-dependent interfacial charge transfer. 4. Charge-exchange breakup of the deuteron with the production of two protons and spin structure of the amplitude of the nucleon charge transfer reaction International Nuclear Information System (INIS) Glagolev, V.V.; Lyuboshits, V.L.; Lyuboshits, V.V.; Piskunov, N.M. 1999-01-01 In the framework of the impulse approximation, the relation between the effective cross section of the charge-exchange breakup of a fast deuteron d + a → (pp) + b and the effective cross section of the charge transfer process n + a → p + b is discussed. In doing so, the effects of the proton identity (Fermi-statistics) and of the Coulomb and strong interactions of protons in the final state are taken into account. The distribution over relative momenta of the protons, produced in the charge-exchange process d + p → (pp) + n in the forward direction, is investigated. At the transfer momenta being close to zero the effective cross section of the charge-exchange breakup of a fast deuteron, colliding with the proton target, is determined only by the spin-flip part of the amplitude of the charge transfer reaction n + p → p + n at the zero angle. It is shown that the study of the process d + p → (pp) + n in a beam of the polarized (aligned) deuterons allows one, in principle, to separate two spin-dependent terms in the amplitude of the charge transfer reaction n + p → p + n, one of which does not conserve and the other one conserves the projection of the nucleon spin onto the direction of momentum at the transition of the neutron into the proton 5. Deflection effects and charge transfer in inner-shell vacancy production International Nuclear Information System (INIS) Swafford, G.L. 1978-01-01 A method used in the calculation of inner shell ionization in asymmetric ion-atom collisions is extended to include projectile deflection effects and charge transfer to the projectile. Work is done in an independent electron model (Hartree-Fock) for the target, and the interaction is treated with the projectile as a time-dependent perturbation of the system. It is shown tht the time-dependent problem can be solved for the projectile moving along the classical hyperbolic trajectory that results from the nuclear repulsion. The method is very efficient due to the utilization the target-centered expansion of the system wave function. This means that all the required matrix elements can be pretabulated and are then available for use at all impact parameters. The method is first applied to the impact-parameter dependence of K-shell ionization by protons incident upon copper in the energy range 0.5 to 2 MeV. Excellent agreement with the experiments of Andersen et al., is found at the lower energy. Less satisfactory agreement is obtained in the higher energy region. Next the projectile is considered to move in a straight line path with constant velocity, and extend the method to include charge transfer between the target inner shells and the K-shell of the projectile. A critical feature of the results is the recognition of the importance of target continuum states of energy approximately equal to the kinetic energy (in the target frame) of the electron on the projectile. An approach is developed to properly include such resonance states in our pseudostate calculation. Selected numerical results are presented to illustrate the method and to demonstrate the projectile energy and nuclear charge dependence of the charge transfer cross sections 6. Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex Energy Technology Data Exchange (ETDEWEB) Haverkate, Lucas A.; Mulder, Fokko M. [Reactor Institute Delft, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft (Netherlands); Zbiri, Mohamed, E-mail: zbiri@ill.fr; Johnson, Mark R. [Institut Laue Langevin, 38042 Grenoble Cedex 9 (France); Carter, Elizabeth [Vibrational Spectroscopy Facility, School of Chemistry, The University of Sydney, NSW 2008 (Australia); Kotlewski, Arek; Picken, S. [ChemE-NSM, Faculty of Chemistry, Delft University of Technology, 2628BL/136 Delft (Netherlands); Kearley, Gordon J. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW 2234 (Australia) 2014-01-07 Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10{sup −2} electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements [L. A. Haverkate, M. Zbiri, M. R. Johnson, B. Deme, H. J. M. de Groot, F. Lefeber, A. Kotlewski, S. J. Picken, F. M. Mulder, and G. J. Kearley, J. Phys. Chem. B 116, 13098 (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems. 7. Synthesis of Stable Interfaces on SnO2 Surfaces for Charge-Transfer Applications Science.gov (United States) Benson, Michelle C. The commercial market for solar harvesting devices as an alternative energy source requires them to be both low-cost and efficient to replace or reduce the dependence on fossil fuel burning. Over the last few decades there has been promising efforts towards improving solar devices by using abundant and non-toxic metal oxide nanomaterials. One particular metal oxide of interest has been SnO2 due to its high electron mobility, wide-band gap, and aqueous stability. However SnO2 based solar cells have yet to reach efficiency values of other metal oxides, like TiO2. The advancement of SnO2 based devices is dependent on many factors, including improved methods of surface functionalization that can yield stable interfaces. This work explores the use of a versatile functionalization method through the use of the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The CuAAC reaction is capable of producing electrochemically, photochemically, and electrocatalytically active surfaces on a variety of SnO2 materials. The resulting charge-transfer characteristics were investigated as well as an emphasis on understanding the stability of the resulting molecular linkage. We determined the CuAAC reaction is able to proceed through both azide-modified and alkyne-modified surfaces. The resulting charge-transfer properties showed that the molecular tether was capable of supporting charge separation at the interface. We also investigated the enhancement of electron injection upon the introduction of an ultra-thin ZrO2 coating on SnO2. Several complexes were used to fully understand the charge-transfer capabilities, including model systems of ferrocene and a ruthenium coordination complex, a ruthenium mononuclear water oxidation catalyst, and a commercial ruthenium based dye. 8. Molecular orbital (SCF-Xα-SW) theory of metal-metal charge transfer processes in minerals - II. Application to Fe2+ --> Ti4+ charge transfer transitions in oxides and silicates Science.gov (United States) Sherman, David M. 1987-01-01 A molecular orbital description, based on Xα-Scattered wave calculations on a (FeTiO10)14− cluster, is given for Fe2+ → Ti4+ charge transfer transitions in minerals. The calculated energy for the lowest Fe2+ → Ti4+ metal-metal charge transfer transition is 18040 cm−1 in reasonable agreement with energies observed in the optical spectra of Fe-Ti oxides and silicates. As in the case of Fe2+ → Fe3+ charge transfer in mixed-valence iron oxides and silicates, Fe2+ → Ti4+ charge transfer is associated with Fe-Ti bonding across shared polyhedral edges. Such bonding results from the overlap of the Fe(t 2g ) and Ti(t 2g ) 3d orbitals. 9. Bane of Hydrogen-Bond Formation on the Photoinduced Charge-Transfer Process in Donor–Acceptor Systems KAUST Repository Alsam, Amani Abdu 2017-03-14 Controlling the ultrafast dynamical process of photoinduced charge transfer at donor acceptor interfaces remains a major challenge for physical chemistry and solar cell communities. The process is complicated by the involvement of other complex dynamical processes, including hydrogen bond formation, energy transfer, and solvation dynamics occurring on similar time scales. In this study, we explore the remarkable impact of hydrogen-bond formation on the interfacial charge transfer between a negatively charged electron donating anionic porphyrin and a positively charged electron accepting pi-conjugated polymer, as a model system in solvents with different polarities and capabilities for hydiogen bonding using femtosecond transient absorption spectroscopy. Unlike the conventional understanding of the key role of hydrogen bonding in promoting the charge-transfer process, our steadystate and time-resolved results reveal that the intervening hydrogen-bonding environment and, consequently, the probable longer spacing between the donor and acceptor molecules significantly hinders the charge-transfer process between them. These results show that site-specific hydrogen bonding and geometric considerations between donor and acceptor can be exploited to control both the charge-transfer dynamics and its efficiency not only at donor acceptor interfaces but also in complex biological systems. 10. An Electronic Structure Approach to Charge Transfer and Transport in Molecular Building Blocks for Organic Optoelectronics Science.gov (United States) Hendrickson, Heidi Phillips A fundamental understanding of charge separation in organic materials is necessary for the rational design of optoelectronic devices suited for renewable energy applications and requires a combination of theoretical, computational, and experimental methods. Density functional theory (DFT) and time-dependent (TD)DFT are cost effective ab-initio approaches for calculating fundamental properties of large molecular systems, however conventional DFT methods have been known to fail in accurately characterizing frontier orbital gaps and charge transfer states in molecular systems. In this dissertation, these shortcomings are addressed by implementing an optimally-tuned range-separated hybrid (OT-RSH) functional approach within DFT and TDDFT. The first part of this thesis presents the way in which RSH-DFT addresses the shortcomings in conventional DFT. Environmentally-corrected RSH-DFT frontier orbital energies are shown to correspond to thin film measurements for a set of organic semiconducting molecules. Likewise, the improved RSH-TDDFT description of charge transfer excitations is benchmarked using a model ethene dimer and silsesquioxane molecules. In the second part of this thesis, RSH-DFT is applied to chromophore-functionalized silsesquioxanes, which are currently investigated as candidates for building blocks in optoelectronic applications. RSH-DFT provides insight into the nature of absorptive and emissive states in silsesquioxanes. While absorption primarily involves transitions localized on one chromophore, charge transfer between chromophores and between chromophore and silsesquioxane cage have been identified. The RSH-DFT approach, including a protocol accounting for complex environmental effects on charge transfer energies, was tested and validated against experimental measurements. The third part of this thesis addresses quantum transport through nano-scale junctions. The ability to quantify a molecular junction via spectroscopic methods is crucial to their 11. Physical adsorption and charge transfer of molecular Br2 on graphene. Science.gov (United States) Chen, Zheyuan; Darancet, Pierre; Wang, Lei; Crowther, Andrew C; Gao, Yuanda; Dean, Cory R; Taniguchi, Takashi; Watanabe, Kenji; Hone, James; Marianetti, Chris A; Brus, Louis E 2014-03-25 We present a detailed study of gaseous Br2 adsorption and charge transfer on graphene, combining in situ Raman spectroscopy and density functional theory (DFT). When graphene is encapsulated by hexagonal boron nitride (h-BN) layers on both sides, in a h-BN/graphene/h-BN sandwich structure, it is protected from doping by strongly oxidizing Br2. Graphene supported on only one side by h-BN shows strong hole doping by adsorbed Br2. Using Raman spectroscopy, we determine the graphene charge density as a function of pressure. DFT calculations reveal the variation in charge transfer per adsorbed molecule as a function of coverage. The molecular adsorption isotherm (coverage versus pressure) is obtained by combining Raman spectra with DFT calculations. The Fowler-Guggenheim isotherm fits better than the Langmuir isotherm. The fitting yields the adsorption equilibrium constant (∼0.31 Torr(-1)) and repulsive lateral interaction (∼20 meV) between adsorbed Br2 molecules. The Br2 molecule binding energy is ∼0.35 eV. We estimate that at monolayer coverage each Br2 molecule accepts 0.09 e- from single-layer graphene. If graphene is supported on SiO2 instead of h-BN, a threshold pressure is observed for diffusion of Br2 along the (somewhat rough) SiO2/graphene interface. At high pressure, graphene supported on SiO2 is doped by adsorbed Br2 on both sides. 12. Coil Design for High Misalignment Tolerant Inductive Power Transfer System for EV Charging Directory of Open Access Journals (Sweden) Kafeel Ahmed Kalwar 2016-11-01 Full Text Available The inductive power transfer (IPT system for electric vehicle (EV charging has acquired more research interest in its different facets. However, the misalignment tolerance between the charging coil (installed in the ground and pick-up coil (mounted on the car chassis, has been a challenge and fundamental interest in the future market of EVs. This paper proposes a new coil design QDQ (Quad D Quadrature that maintains the high coupling coefficient and efficient power transfer during reasonable misalignment. The QDQ design makes the use of four adjacent circular coils and one square coil, for both charging and pick-up side, to capture the maximum flux at any position. The coil design has been modeled in JMAG software for calculation of inductive parameters using the finite element method (FEM, and its hardware has been tested experimentally at various misaligned positions. The QDQ coils are shown to be capable of achieving good coupling coefficient and high efficiency of the system until the misalignment displacement reaches 50% of the employed coil size. 13. Ultrafast dynamics of solvation and charge transfer in a DNA-based biomaterial. Science.gov (United States) Choudhury, Susobhan; Batabyal, Subrata; Mondol, Tanumoy; Sao, Dilip; Lemmens, Peter; Pal, Samir Kumar 2014-05-01 Charge migration along DNA molecules is a key factor for DNA-based devices in optoelectronics and biotechnology. The association of a significant amount of water molecules in DNA-based materials for the intactness of the DNA structure and their dynamic role in the charge-transfer (CT) dynamics is less documented in contemporary literature. In the present study, we have used a genomic DNA-cetyltrimethyl ammonium chloride (CTMA) complex, a technological important biomaterial, and Hoechest 33258 (H258), a well-known DNA minor groove binder, as fluorogenic probe for the dynamic solvation studies. The CT dynamics of CdSe/ZnS quantum dots (QDs; 5.2 nm) embedded in the as-prepared and swollen biomaterial have also been studied and correlated with that of the timescale of solvation. We have extended our studies on the temperature-dependent CT dynamics of QDs in a nanoenvironment of an anionic, sodium bis(2-ethylhexyl)sulfosuccinate reverse micelle (AOT RMs), whereby the number of water molecules and their dynamics can be tuned in a controlled manner. A direct correlation of the dynamics of solvation and that of the CT in the nanoenvironments clearly suggests that the hydration barrier within the Arrhenius framework essentially dictates the charge-transfer dynamics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 14. Single-crystal charge transfer interfaces for efficient photonic devices (Conference Presentation) Science.gov (United States) Alves, Helena; Pinto, Rui M.; Maçôas, Ermelinda M. S.; Baleizão, Carlos; Santos, Isabel C. 2016-09-01 Organic semiconductors have unique optical, mechanical and electronic properties that can be combined with customized chemical functionality. In the crystalline form, determinant features for electronic applications such as molecular purity, the charge mobility or the exciton diffusion length, reveal a superior performance when compared with materials in a more disordered form. Combining crystals of two different conjugated materials as even enable a new 2D electronic system. However, the use of organic single crystals in devices is still limited to a few applications, such as field-effect transistors. In 2013, we presented the first system composed of single-crystal charge transfer interfaces presenting photoconductivity behaviour. The system composed of rubrene and TCNQ has a responsivity reaching 1 A/W, corresponding to an external quantum efficiency of nearly 100%. A similar approach, with a hybrid structure of a PCBM film and rubrene single crystal also presents high responsivity and the possibility to extract excitons generated in acceptor materials. This strategy led to an extended action towards the near IR. By adequate material design and structural organisation of perylediimides, we demonstrate that is possible to improve exciton diffusion efficiency. More recently, we have successfully used the concept of charge transfer interfaces in phototransistors. These results open the possibility of using organic single-crystal interfaces in photonic applications. 15. Single Molecule Spectroelectrochemistry of Interfacial Charge Transfer Dynamics In Hybrid Organic Solar Cell Energy Technology Data Exchange (ETDEWEB) Pan, Shanlin [Univ. of Alabama, Tuscaloosa, AL (United States) 2014-11-16 Our research under support of this DOE grant is focused on applied and fundamental aspects of model organic solar cell systems. Major accomplishments are: 1) we developed a spectroelectorchemistry technique of single molecule single nanoparticle method to study charge transfer between conjugated polymers and semiconductor at the single molecule level. The fluorescence of individual fluorescent polymers at semiconductor surfaces was shown to exhibit blinking behavior compared to molecules on glass substrates. Single molecule fluorescence excitation anisotropy measurements showed the conformation of the polymer molecules did not differ appreciably between glass and semiconductor substrates. The similarities in molecular conformation suggest that the observed differences in blinking activity are due to charge transfer between fluorescent polymer and semiconductor, which provides additional pathways between states of high and low fluorescence quantum efficiency. Similar spectroelectrochemistry work has been done for small organic dyes for understand their charge transfer dynamics on various substrates and electrochemical environments; 2) We developed a method of transferring semiconductor nanoparticles (NPs) and graphene oxide (GO) nanosheets into organic solvent for a potential electron acceptor in bulk heterojunction organic solar cells which employed polymer semiconductor as the electron donor. Electron transfer from the polymer semiconductor to semiconductor and GO in solutions and thin films was established through fluorescence spectroscopy and electroluminescence measurements. Solar cells containing these materials were constructed and evaluated using transient absorption spectroscopy and dynamic fluorescence techniques to understand the charge carrier generation and recombination events; 3) We invented a spectroelectorchemistry technique using light scattering and electroluminescence for rapid size determination and studying electrochemistry of single NPs in an 16. Bane of Hydrogen-Bond Formation on the Photoinduced Charge-Transfer Process in Donor–Acceptor Systems KAUST Repository Alsam, Amani Abdu; Adhikari, Aniruddha; Parida, Manas R.; Aly, Shawkat Mohammede; Bakr, Osman; Mohammed, Omar F. 2017-01-01 Controlling the ultrafast dynamical process of photoinduced charge transfer at donor acceptor interfaces remains a major challenge for physical chemistry and solar cell communities. The process is complicated by the involvement of other complex 17. State-selective charge transfer and excitation in ion-ion interactions at intermediate and high energies International Nuclear Information System (INIS) Samanta, R; Purkait, M 2012-01-01 Boundary Corrected Continuum Intermediate State (BCCIS) approximation and Classical Trajectory Monte Carlo (CTMC) methods are applied to calculate the charge transfer and excitation cross sections for ion-ion collisions. 18. Low energy cross section data for ion-molecule reactions in hydrogen systems and for charge transfer of multiply charged ions with atoms and molecules International Nuclear Information System (INIS) Okuno, Kazuhiko 2007-04-01 Systematic cross section measurements for ion-molecule reactions in hydrogen systems and for charge transfer of multiply charged ions in low energy collisions with atoms and molecules have been performed continuously by the identical apparatus installed with an octo-pole ion beam guide (OPIG) since 1980 till 2004. Recently, all of accumulated cross section data for a hundred collision systems has been entered into CMOL and CHART of the NIFS atomic and molecular numerical database together with some related cross section data. In this present paper, complicated ion-molecule reactions in hydrogen systems are revealed and the brief outlines of specific properties in low energy charge transfer collisions of multiply charged ions with atoms and molecules are introduced. (author) 19. A statewide teleradiology system reduces radiation exposure and charges in transferred trauma patients. Science.gov (United States) Watson, Justin J J; Moren, Alexis; Diggs, Brian; Houser, Ben; Eastes, Lynn; Brand, Dawn; Bilyeu, Pamela; Schreiber, Martin; Kiraly, Laszlo 2016-05-01 Trauma transfer patients routinely undergo repeat imaging because of inefficiencies within the radiology system. In 2009, the virtual private network (VPN) telemedicine system was adopted throughout Oregon allowing virtual image transfer between hospitals. The startup cost was a nominal3,000 per hospital. A retrospective review from 2007 to 2012 included 400 randomly selected adult trauma transfer patients based on a power analysis (200 pre/200 post). The primary outcome evaluated was reduction in repeat computed tomography (CT) scans. Secondary outcomes included cost savings, emergency department (ED) length of stay (LOS), and spared radiation. All data were analyzed using Mann-Whitney U and chi-square tests. P less than .05 indicated significance. Spared radiation was calculated as a weighted average per body region, and savings was calculated using charges obtained from Oregon Health and Science University radiology current procedural terminology codes. Four-hundred patients were included. Injury Severity Score, age, ED and overall LOS, mortality, trauma type, and gender were not statistically different between groups. The percentage of patients with repeat CT scans decreased after VPN implementation: CT abdomen (13.2% vs 2.8%, P < .01) and cervical spine (34.4% vs 18.2%, P < .01). Post-VPN, the total charges saved in 2012 for trauma transfer patients was \$333,500, whereas the average radiation dose spared per person was 1.8 mSV. Length of stay in the ED for patients with Injury Severity Score less than 15 transferring to the ICU was decreased (P < .05). Implementation of a statewide teleradiology network resulted in fewer total repeat CT scans, significant savings, decrease in radiation exposure, and decreased LOS in the ED for patients with less complex injuries. The potential for health care savings by widespread adoption of a VPN is significant. Copyright © 2016 Elsevier Inc. All rights reserved. 20. Refrigerant charge, pressure drop, and condensation heat transfer in flattened tubes Energy Technology Data Exchange (ETDEWEB) Wilson, M J; Newell, T A; Chato, J C [University of Illinois, Urbana, IL (United States). Dept. of Mechanical and Industrial Engineering; Infante Ferreira, C A [Delft University of Technology (Netherlands). Laboratory for Refrigeration and Indoor Climate Control 2003-06-01 Horizontal smooth and microfinned copper tubes with an approximate diameter of 9 mm were successively flattened in order to determine changes in flow field characteristics as a round tube is altered into a flattened tube profile. Refrigerants R134a and R410A were investigated over a mass flux range from 75 to 400 kg m{sup -2} s{sup -}2{sup 1} and a quality range from approximately 10-80%. For a given refrigerant mass flow rate, the results show that a significant reduction in refrigerant charge is possible. Pressure drop results show increases of pressure drop at a given mass flux and quality as a tube profile is flattened. Heat transfer results indicate enhancement of the condensation heat transfer coefficient as a tube is flattened. Flattened tubes with an 18{sup o} helix angle displayed the highest heat transfer coefficients. Smooth tubes and axial microfin tubes displayed similar levels of heat transfer enhancement. Heat transfer enhancement is dependent on the mass flux, quality and tube profile. (author) 1. Theoretical perspectives on electron transfer and charge separation events in photochemical water cleavage systems International Nuclear Information System (INIS) Kozak, J.J.; Lenoir, P.M.; Musho, M.K.; Tembe, B.L. 1984-01-01 We study in this paper the dynamics induced by models for photochemical water cleavage systems, focusing on the spatial and temporal factors influencing electron transfer and charge separation processes in such systems. The reaction-diffusion theory is formulated in full generality and the consequences explored in a number of spatio-temporal regimes, viz. the spatially homogeneous system in the long-time limit (i.e. the steady state for a well-stirred system), the spatially homogeneous system in evolution, and the spatially inhomogeneous system in evolution (where, in the latter study, we consider electron transfer at the cluster surface to be governed by a rate constant that reflects the localized nature of such processes). The results of numerical simulations are presented for all three cases and used to highlight the importance of heterogeneous environments in enhancing the cage escape yield of charge separated species, and to demonstrate the dependence of the hydrogen yield on the localization of electron-transfer processes in the vicinity of the microcatalyst surface 2. Excitation and charge transfer in low-energy hydrogen atom collisions with neutral iron Science.gov (United States) Barklem, P. S. 2018-05-01 Data for inelastic processes due to hydrogen atom collisions with iron are needed for accurate modelling of the iron spectrum in late-type stars. Excitation and charge transfer in low-energy Fe+H collisions is studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multi-channel Landau-Zener model. An extensive calculation including 166 covalent states and 25 ionic states is presented and rate coefficients are calculated for temperatures in the range 1000-20 000 K. The largest rates are found for charge transfer processes to and from two clusters of states around 6.3 and 6.6 eV excitation, corresponding in both cases to active 4d and 5p electrons undergoing transfer. Excitation and de-excitation processes among these two sets of states are also significant. Full Tables and rate coefficient data are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/612/A90 3. Low-Energy Charge Transfer in Multiply-Charged Ion-Atom Collisions Studied with the Combined SCVB-MOCC Approach OpenAIRE Cooper, D. L.; Stancil, P. C.; Turner, A. R.; Wang, J. G.; Clarke, N. J.; Zygelman, B. 2002-01-01 A survey of theoretical studies of charge transfer involving collisions of multiply-charged ions with atomic neutrals (H and He) is presented. The calculations utilized the quantum-mechanical molecular-orbital close-coupling (MOCC) approach where the requisite potential curves and coupling matrix elements have been obtained with the spin-coupled valence bond (SCVB) method. Comparison is made among various collision partners, for equicharged systems, where it is illustrated that even for total... 4. Charge transfer and partial pinning at the contacts as the origin of a double dip in the transfer characteristics of graphene-based field-effect transistors International Nuclear Information System (INIS) Di Bartolomeo, Antonio; Giubileo, Filippo; Santandrea, Salvatore; Romeo, Francesco; Citro, Roberta; Schroeder, Thomas; Lupina, Grzegorz 2011-01-01 We discuss the origin of an additional dip other than the charge neutrality point observed in the transfer characteristics of graphene-based field-effect transistors with a Si/SiO 2 substrate used as the back-gate. The double dip is proved to arise from charge transfer between the graphene and the metal electrodes, while charge storage at the graphene/SiO 2 interface can make it more evident. Considering a different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all the features observed in the gate voltage loops. We finally show that the double dip enhanced hysteresis in the transfer characteristics can be exploited to realize graphene-based memory devices. 5. Study of the cold charge transfer state separation at the TQ1/PC71 BM interface. Science.gov (United States) Volpi, Riccardo; Linares, Mathieu 2017-05-30 Charge transfer (CT) state separation is one of the most critical processes in the functioning of an organic solar cell. In this article, we study a bilayer of TQ1 and PC 71 BM molecules presenting disorder at the interface, obtained by means of Molecular Dynamics. The study of the CT state splitting can be first analyzed through the CT state splitting diagram, introduced in a previous work. Through this analysis, we identify the possibility of CT state splitting within Marcus Theory in function of the electric field. Once the right range of electric fields has been identified, we perform Kinetic Monte Carlo simulations to estimate percentages and times for the CT state splitting and the free charge carriers collection. Statistical information extracted from these simulations allows us to highlight the importance of polarization and to test the limits of the predictions given by the CT state splitting diagram. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc. 6. Charge transfer properties and photoelectrocatalytic activity of TiO{sub 2}/MWCNT hybrid Energy Technology Data Exchange (ETDEWEB) Jiang Liaochuan [Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China); Zhang Weide, E-mail: zhangwd@scut.edu.c [Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China) 2010-12-15 The vertically aligned multiwalled carbon nanotube (MWCNT) arrays on tantalum foils were successfully coated with TiO{sub 2} nanoparticles by a hydrothermal process. The prepared TiO{sub 2}/MWCNT hybrid was characterized by scanning electron microscopy and transmission electron microscopy. The charge transfer properties and photocatalytic degradation of rhodamine B with and without bias potential under UV irradiation were investigated. The MWCNTs promoted the separation of photoinduced carriers in the TiO{sub 2}, thus enhanced photocatalytic activity. Applying bias potential on the photoanode further enhanced its catalytic activity. The efficient charge transportation and high photoelectrocatalytic activity towards degradation of rhodamine B made this hybrid material promising for photocatalyst and for the development of photoelectrical devices. 7. Charge-Transfer Effects in Ligand Exchange Reactions of Au25 Monolayer-Protected Clusters. Science.gov (United States) Carducci, Tessa M; Blackwell, Raymond E; Murray, Royce W 2015-04-16 Reported here are second-order rate constants of associative ligand exchanges of Au25L18 nanoparticles (L = phenylethanethiolate) of various charge states, measured by proton nuclear magnetic resonance at room temperature and below. Differences in second-order rate constants (M(-1) s(-1)) of ligand exchange (positive clusters ∼1.9 × 10(-5) versus negative ones ∼1.2 × 10(-4)) show that electron depletion retards ligand exchange. The ordering of rate constants between the ligands benzeneselenol > 4-bromobenzene thiol > benzenethiol reveals that exchange is accelerated by higher acidity and/or electron donation capability of the incoming ligand. Together, these observations indicate that partial charge transfer occurs between the nanoparticle and ligand during the exchange and that this is a rate-determining effect in the process. 8. ANISOTROPY EFFECTS IN SINGLE-ELECTRON TRANSFER BETWEEN LASER-EXCITED ATOMS AND HIGHLY-CHARGED IONS NARCIS (Netherlands) Recent collision experiments are reviewed in which one-electron transfer between laser excited target atoms and (highly charged) keV-ions has been studied. Especially results showing a dependence of the charge exchange on the initial target orbital alignment are discussed. The question to what 9. Charge transfer and injection barrier at the metal-organic interfaces Science.gov (United States) Yan, Li 2002-09-01 The metal-organic interface plays a critical role in determining the functionality and performance of many innovative organic based devices. It has attracted extensive research interests in recent years. This thesis presents investigations of the electronic structures of organic materials, such as tris-(8-hydroxyquinoline) aluminum (Alq3) and copper phthalocyanine (CuPc), during their interface formation with metals. The characterization is accomplished by X-ray and ultraviolet photoelectron spectroscopes (XPS and UPS) and inverse photoelectron spectroscopy (IPES). As discussed herein, both occupied and unoccupied electronic states at the interfaces are carefully examined in different aspects. In Chapter 4, the charge transfer and chemical reaction at various metal/Alq3 interfaces are investigated using XPS and UPS to study the electron injection into the Alga film. Electron transfer from the low work function metal and Al/LiF(CsF) bilayer to the Alga has been observed. The role of the dielectric and possible chemistry at the interface are discussed in comparison of the low work function metals. Further in Chapter 5, the origin of the metal-interface dipole and the estimation of charge injection barrier is explored using several organic materials. A thermodynamic equilibrium model is extended to explain the relation between the charge transfer process ad the interface dipole. Further, in Chapter 6 the combination of XPS, UPS and IPES detailed the evolution of both occupied and unoccupied energy states during the alkali metal doping. The energy gap modification in organic due to metal doping is observed directly for the spectra. Chapter 7 provides stability study of the organic thin films under x-ray and UV light. The results verify the usability of UPS and XPS for the organic materials used in the thesis. Chapter 7 also shows the secondary ion mass spectroscopy results of metal diffusion in organic thin films. 10. Interface charge transfer process in ZnO:Mn/ZnS nanocomposites Energy Technology Data Exchange (ETDEWEB) Stefan, M.; Toloman, D., E-mail: dana.toloman@itim-cj.ro; Popa, A. [National Institute for R & D of Isotopic and Molecular Technology (Romania); Mesaros, A. [Technical University of Cluj-Napoca, Superconductivity, Spintronics and Surface Science Center – C4S (Romania); Vasile, O. R. [University “Politehnica” from Bucharest, Faculty of Applied Chemistry and Material Science (Romania); Leostean, C.; Pana, O. [National Institute for R & D of Isotopic and Molecular Technology (Romania) 2016-03-15 ZnO:Mn/ZnS nanocomposites were prepared by seed-mediated growth of ZnS QDs onto the preformed ZnO:Mn nanoparticles. The formation of the nanocomposite structure has been evidenced by XRD, HRTEM, and XPS. The architecture of the nanocomposite with outer ZnS QDs around ZnO:Mn cores is sustained by the sulfur and oxygen depth profiles resulted from XPS. When the two components are brought together, the band gap of ZnS component decreases while that of ZnO:Mn increases. It is the result of interface charge transfer from ZnO:Mn to ZnS QDs. Here ZnO:Mn valence states are extended through the interface into unoccupied gap states of ZnS. The energy band setup is modified from a type II into a type I band alignment. The process is accompanied by enhancement of composite UV emission of PL spectra as compared to its counterparts. The charge transfer from valence band also determines the increase of the core-polarization effect of sshell electrons at Mn{sup 2+} nucleus, thus determining the increase of the hyperfine field through the reduction of the covalency degree of Zn(Mn)–O bonds. The quantum confinement in ZnS QDs promotes the ferromagnetic coupling of singly occupied states due to Zn vacancies determining a superparamagnetic behavior of the ensemble. When the nanocomposites are formed, due to interface charge transfer effects, an increased number of filled cation vacancies in ZnS QDs develop, thus disrupting the pre-existing ferromagnetic coupling between spins resulting in a significant reduction of the overall saturation magnetization. The possibility to modulate nanocomposite properties by controlling the interface interactions may be foreseen in these types of materials. 11. Theoretical Investigation of OCN(-) Charge Transfer Complexes in Condensed Phase Media: Spectroscopic Properties in Amorphous Ice Science.gov (United States) Park, Jin-Young; Woon, David E. 2004-01-01 Density functional theory (DFT) calculations of cyanate (OCN(-)) charge-transfer complexes were performed to model the "XCN" feature observed in interstellar icy grain mantles. OCN(-) charge-transfer complexes were formed from precursor combinations of HNCO or HOCN with either NH3 or H2O. Three different solvation strategies for realistically modeling the ice matrix environment were explored, including (1) continuum solvation, (2) pure DFT cluster calculations, and (3) an ONIOM DFT/PM3 cluster calculation. The model complexes were evaluated by their ability to reproduce seven spectroscopic measurements associated with XCN: the band origin of the OCN(-) asymmetric stretching mode, shifts in that frequency due to isotopic substitutions of C, N, O, and H, plus two weak features. The continuum solvent field method produced results consistent with some of the experimental data but failed to account for other behavior due to its limited capacity to describe molecular interactions with solvent. DFT cluster calculations successfully reproduced the available spectroscopic measurements very well. In particular, the deuterium shift showed excellent agreement in complexes where OCN(-) was fully solvated. Detailed studies of representative complexes including from two to twelve water molecules allowed the exploration of various possible solvation structures and provided insights into solvation trends. Moreover, complexes arising from cyanic or isocyanic acid in pure water suggested an alternative mechanism for the formation of OCN(-) charge-transfer complexes without the need for a strong base such as NH3 to be present. An extended ONIOM (B3LYP/PM3) cluster calculation was also performed to assess the impact of a more realistic environment on HNCO dissociation in pure water. 12. Interfacial electronic charge transfer and density of states in short period Cu/Cr multilayers; TOPICAL International Nuclear Information System (INIS) Barbee, T W; Bello, A F; Klepeis, J E; Van Buuren, T 1999-01-01 Nanometer period metallic multilayers are ideal structures to investigate electronic phenomena at interfaces between metal films since interfacial atoms comprise a large atomic fraction of the samples. The Cu/Cr binary pair is especially suited to study the interfaces in metals since these elements are mutually insoluble, thus eliminating mixing effects and compound formation and the lattice mismatch is very small. This allows the fabrication of high structural quality Cu/Cr multilayers that have a structure which can be approximated in calculations based on idealized atomic arrangements. The electronic structure of the Cu and the Cr layers in several samples of thin Cu/Cr multilayers were studied using x-ray absorption spectroscopy (XAS). Total electron yield was measured and used to study the white lines at the Cu L(sub 2) and L(sub 3) absorption edges. The white lines at the Cu absorption edges are strongly related to the unoccupied d-orbitals and are used to calculate the amount of charge transfer between the Cr and Cu atoms in interfaces. Analysis of the Cu white lines show a charge transfer of 0.026 electrons/interfacial Cu atom to the interfacial Cr atoms. In the Cu XAS spectra we also observe a van Hove singularity between the L(sub 2) and L(sub 3) absorption edges as expected from the structural analysis. The absorption spectra are compared to partial density of states obtained from a full-potential linear muffin-tin orbital calculation. The calculations support the presence of charge transfer and indicate that it is localized to the first two interfacial layers in both Cu and Cr 13. Fragment-orbital tunneling currents and electronic couplings for analysis of molecular charge-transfer systems. Science.gov (United States) Hwang, Sang-Yeon; Kim, Jaewook; Kim, Woo Youn 2018-04-04 In theoretical charge-transfer research, calculation of the electronic coupling element is crucial for examining the degree of the electronic donor-acceptor interaction. The tunneling current (TC), representing the magnitudes and directions of electron flow, provides a way of evaluating electronic couplings, along with the ability of visualizing how electrons flow in systems. Here, we applied the TC theory to π-conjugated organic dimer systems, in the form of our fragment-orbital tunneling current (FOTC) method, which uses the frontier molecular-orbitals of system fragments as diabatic states. For a comprehensive test of FOTC, we assessed how reasonable the computed electronic couplings and the corresponding TC densities are for the hole- and electron-transfer databases HAB11 and HAB7. FOTC gave 12.5% mean relative unsigned error with regard to the high-level ab initio reference. The shown performance is comparable with that of fragment-orbital density functional theory, which gave the same error by 20.6% or 13.9% depending on the formulation. In the test of a set of nucleobase π stacks, we showed that the original TC expression is also applicable to nondegenerate cases under the condition that the overlap between the charge distributions of diabatic states is small enough to offset the energy difference. Lastly, we carried out visual analysis on the FOTC densities of thiophene dimers with different intermolecular alignments. The result depicts an intimate topological connection between the system geometry and electron flow. Our work provides quantitative and qualitative grounds for FOTC, showing it to be a versatile tool in characterization of molecular charge-transfer systems. 14. Molecular distortion and charge transfer effects in ZnPc/Cu(111) KAUST Repository Amin, B.; Nazir, S.; Schwingenschlö gl, Udo 2013-01-01 The adsorption geometry and electronic properties of a zinc-phthalocyanine molecule on a Cu(111) substrate are studied by density functional theory. In agreement with experiment, we find remarkable distortions of the molecule, mainly as the central Zn atom tends towards the substrate to minimize the Zn-Cu distance. As a consequence, the Zn-N chemical bonding and energy levels of the molecule are significantly modified. However, charge transfer induces metallic states on the molecule and therefore is more important for the ZnPc/Cu(111) system than the structural distortions. 15. Specific optical signalling of anions via intramolecular charge transfer pathway based on acridinedione fluorophore International Nuclear Information System (INIS) Thiagarajan, Viruthachalam; Ramamurthy, Perumal 2007-01-01 We present a simple but highly specific acridinedione fluorophore (ADD-1) that acts both as a fluorescent and colorimetric sensor for anions in acetonitrile. The specific optical signalling of ADD-1 is due to the formation of new distinct intramolecular charge transfer (ICT) emitting states in the presence of AcO - (490 nm), H 2 PO 4 - (440 nm), and F - (510 nm) over other anions. Presence of F - shows a colour change that is perceptible to the naked eye, from colourless to an intense fluorescent green due to the deprotonation of acridinedione ring amino hydrogen 16. Electronic, structural and chemical effects of charge-transfer at organic/inorganic interfaces Science.gov (United States) Otero, R.; Vázquez de Parga, A. L.; Gallego, J. M. 2017-07-01 During the last decade, interest on the growth and self-assembly of organic molecular species on solid surfaces spread over the scientific community, largely motivated by the promise of cheap, flexible and tunable organic electronic and optoelectronic devices. These efforts lead to important advances in our understanding of the nature and strength of the non-bonding intermolecular interactions that control the assembly of the organic building blocks on solid surfaces, which have been recently reviewed in a number of excellent papers. To a large extent, such studies were possible because of a smart choice of model substrate-adsorbate systems where the molecule-substrate interactions were purposefully kept low, so that most of the observed supramolecular structures could be understood simply by considering intermolecular interactions, keeping the role of the surface always relatively small (although not completely negligible). On the other hand, the systems which are more relevant for the development of organic electronic devices include molecular species which are electron donors, acceptors or blends of donors and acceptors. Adsorption of such organic species on solid surfaces is bound to be accompanied by charge-transfer processes between the substrate and the adsorbates, and the physical and chemical properties of the molecules cannot be expected any longer to be the same as in solution phase. In recent years, a number of groups around the world have started tackling the problem of the adsorption, self- assembly and electronic and chemical properties of organic species which interact rather strongly with the surface, and for which charge-transfer must be considered. The picture that is emerging shows that charge transfer can lead to a plethora of new phenomena, from the development of delocalized band-like electron states at molecular overlayers, to the existence of new substrate-mediated intermolecular interactions or the strong modification of the chemical 17. Laser-induced charge transfer in the HeH2+ quasimolecule International Nuclear Information System (INIS) Errea, L.F.; Mendez, L.; Riera, A. 1983-01-01 In a recent publication, the charge transfer cross section for He 2+ +H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions 18. Effective interactions between concentration fluctuations and charge transfer in chemically ordering liquid alloys International Nuclear Information System (INIS) Akdeniz, Z.; Tosi, M.P. 1992-08-01 The correlations between long-wavelength fluctuations of concentration in a liquid binary alloy are determined by a balance between an elastic strain free energy and an Ornstein-Zernike effective interaction. The latter is extracted from thermodynamic data in the case of the Li-Pb system, which is well known to chemically order with stoichiometric composition corresponding to Li 4 Pb. Strong attractive interactions between concentration fluctuations near the composition of chemical ordering originate from electronic charge transfer, which is estimated from the electron-ion partial structure factors as functions of composition in the liquid alloy. (author). 20 refs, 2 figs 19. On the charge transfer between single-walled carbon nanotubes and graphene International Nuclear Information System (INIS) Rao, Rahul; Pierce, Neal; Dasgupta, Archi 2014-01-01 It is important to understand the electronic interaction between single-walled carbon nanotubes (SWNTs) and graphene in order to use them efficiently in multifunctional hybrid devices. Here, we deposited SWNT bundles on graphene-covered copper and SiO 2 substrates by chemical vapor deposition and investigated the charge transfer between them by Raman spectroscopy. Our results revealed that, on both copper and SiO 2 substrates, graphene donates electrons to the SWNTs, resulting in p-type doped graphene and n-type doped SWNTs. 20. Surface charges and J H Poynting’s disquisitions on energy transfer in electrical circuits Science.gov (United States) Matar, M.; Welti, R. 2017-11-01 In this paper we review applications given by J H Poynting (1884) on the transfer of electromagnetic energy in DC circuits. These examples were strongly criticized by O Heaviside (1887). Heaviside stated that Poynting had a misconception about the nature of the electric field in the vicinity of a wire through which a current flows. The historical review of this conflict and its resolution based on the consideration of electrical charges on the surface of the wires can be useful for student courses on electromagnetism or circuit theory. 1. Study of charge transfer complexes of menadione (vitamin K 3) with a series of anilines Science.gov (United States) Pal, Purnendu; Saha, Avijit; Mukherjee, Asok K.; Mukherjee, Dulal C. 2004-01-01 Menadione (vitamin K 3) has been shown to form charge transfer complexes with N, N-dimethyl aniline, N, N-dimethyl p-toluidine and N, N-dimethyl m-toluidine in CCl 4 medium. The CT transition energies are well correlated with the ionisation potentials of the anilines. The formation constants of the complexes have been determined at a number of temperatures from which the enthalpies and entropies of formation have been obtained. The formation constants exhibit a very good linear free energy relationship (Hammett) at all the temperatures studied. 2. Formation of an intermolecular charge-transfer compound in UHV codeposited tetramethoxypyrene and tetracyanoquinodimethane DEFF Research Database (Denmark) Medjanik, K.; Perkert, S.; Naghavi, S. 2010-01-01 Ultrahigh vacuum (UHV)-deposited films of the mixed phase of tetramethoxypyrene and tetracyanoquinodimethane (TMP -TCNQ ) on gold have been studied using ultraviolet photoelectron spectroscopy (UPS), x-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning tunneling spectroscopy (STS......). The formation of an intermolecular charge-transfer (CT) compound is evident from the appearance of new reflexes in XRD (d =0.894nm and d =0.677nm). A softening of the CN stretching vibration (redshift by 7 cm⊃-1) of TCNQ is visible in the IR spectra, being indicative of a CT on the order of 0.3e from TMP... 3. Metallic conductivity in a disordered charge-transfer salt derived from cis-BET-TTF Energy Technology Data Exchange (ETDEWEB) Rovira, C. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Tarres, J. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Ribera, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Veciana, J. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Canadell, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Molins, E. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Mas, M. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain); Laukhin, V. [Inst. de Ciencia de Materials de Barcelona (CSIC) (Spain)]\|[Rossijskaya Akademiya Nauk, Chernogolovka (Russian Federation). Inst. Khimicheskoj Fiziki; Doublet, M.L. [Lab. de Structure et Dynamique (CNRS), Univ. de Montpellier 2 (France); Cowan, D.O. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry; Yang, S. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry 1997-02-28 The first example of a metallic charge-transfer salt derived from cis-bis(ethylenethio)-tetrathiafulvalene (BET-TTF) is reported. (BET-TTF){sub 2}SCN and (BET-TTF)SCN salts were obtained by electrocrystallization starting from trans-BET-TTF. X-ray crystal structure of the mixed-valence salt revealed that trans-cis isomerization occurs upon one electron oxidation. In spite of the structural disorder in both BET-TTF and the counterion, 2:1 salt is metallic down to 60 K and then resistance increases slowly down to 4 K. (orig.) 4. Laser-induced charge transfer in the HeH/sup 2 +/ quasimolecule Energy Technology Data Exchange (ETDEWEB) Errea, L.F.; Mendez, L.; Riera, A. 1983-11-01 In a recent publication, the charge transfer cross section for He/sup 2 +/+H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions. 5. Ab initio study of H + + H 2 collisions: Elastic/inelastic and charge transfer processes Science.gov (United States) Saieswari, A.; Kumar, Sanjay 2007-12-01 An ab initio full configuration interaction study has been undertaken to obtain the global potential energy surfaces for the ground and the first excited electronic state of the H + + H 2 system employing Dunning's cc-pVQZ basis set. Using the ab initio approach the corresponding quasi-diabatic potential energy surfaces and coupling potentials have been obtained. A time-independent quantum mechanical study has been also undertaken for both the inelastic and charge transfer processes at the experimental collision energy Ec.m. = 20.0 eV and the preliminary results show better agreement with the experimental data as compared to the earlier available theoretical studies. 6. Estimation of instantaneous heat transfer coefficients for a direct-injection stratified-charge rotary engine Science.gov (United States) Lee, C. M.; Addy, H. E.; Bond, T. H.; Chun, K. S.; Lu, C. Y. 1987-01-01 The main objective of this report was to derive equations to estimate heat transfer coefficients in both the combustion chamber and coolant pasage of a rotary engine. This was accomplished by making detailed temperature and pressure measurements in a direct-injection stratified-charge rotary engine under a range of conditions. For each sppecific measurement point, the local physical properties of the fluids were calculated. Then an empirical correlation of the coefficients was derived by using a multiple regression program. This correlation expresses the Nusselt number as a function of the Prandtl number and Reynolds number. 7. Spectroscopy of charge transfer complexes of four amino acids as organic two-dimensional conductors International Nuclear Information System (INIS) Padhiyar, Ashvin; Patel, A J; Oza, A T 2007-01-01 It is found in this study that four amino acids, namely asparagine, arginine, histidine and glutamine form two-dimensional conducting systems which are charge transfer complexes (CTCs) with organic acceptors like TCNQ, TCNE, chloranil, DDQ, TNF and iodine. It is verified using optical absorption edges that these are 2d conductors like transition metal dichalcogenides obeying absorption functions different from 1d and 3d conductors. This 2d nature is related to the network of intermolecular H-bonding in these complexes, which leads to a global H-bonded network resulting in the absence of local deformation due to the relaxation of strain 8. Charge-transfer complexes between p-toluidine and iodine in solution: a kinetic study International Nuclear Information System (INIS) Beggiato, G.; Casalbore, G.; Marconi, G.; Baraldi, C. 1985-01-01 The kinetics of charge-transfer interaction between p-toluidine and iodine in methylene chloride was investigated in depth. The thermal process of formation of the 'inner' complex was found to proceed to an equilibrium. The photochemical process follows a different reaction coordinate, going through the formation of an exciplex between the excited 'outer' complex and the amine ground state. In both cases the same ionic complex (Am 2 I + I - 3 , where Am stands for p-toluidine) was detected as the final product. (Author) 9. Molecular distortion and charge transfer effects in ZnPc/Cu(111) KAUST Repository Amin, B. 2013-04-23 The adsorption geometry and electronic properties of a zinc-phthalocyanine molecule on a Cu(111) substrate are studied by density functional theory. In agreement with experiment, we find remarkable distortions of the molecule, mainly as the central Zn atom tends towards the substrate to minimize the Zn-Cu distance. As a consequence, the Zn-N chemical bonding and energy levels of the molecule are significantly modified. However, charge transfer induces metallic states on the molecule and therefore is more important for the ZnPc/Cu(111) system than the structural distortions. 10. Absolute Charge Transfer and Fragmentation Cross Sections in He2+-C60 Collisions International Nuclear Information System (INIS) Rentenier, A.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.; Ruiz, L. F.; Diaz-Tendero, S.; Alcami, M.; Martin, F.; Zarour, B.; Hanssen, J.; Hervieux, P.-A.; Politis, M. F. 2008-01-01 We have determined absolute charge transfer and fragmentation cross sections in He 2+ +C 60 collisions in the impact-energy range 0.1-250 keV by using a combined experimental and theoretical approach. We have found that the cross sections for the formation of He + and He 0 are comparable in magnitude, which cannot be explained by the sole contribution of pure single and double electron capture but also by contribution of transfer-ionization processes that are important even at low impact energies. The results show that multifragmentation is important only at impact energies larger than 40 keV; at lower energies, sequential C 2 evaporation is the dominant process 11. Femtosecond stimulated Raman evidence for charge-transfer character in pentacene singlet fission. Science.gov (United States) Hart, Stephanie M; Silva, W Ruchira; Frontiera, Renee R 2018-02-07 Singlet fission is a spin-allowed process in which an excited singlet state evolves into two triplet states. We use femtosecond stimulated Raman spectroscopy, an ultrafast vibrational technique, to follow the molecular structural evolution during singlet fission in order to determine the mechanism of this process. In crystalline pentacene, we observe the formation of an intermediate characterized by pairs of excited state peaks that are red- and blue-shifted relative to the ground state features. We hypothesize that these features arise from the formation of cationic and anionic species due to partial transfer of electron density from one pentacene molecule to a neighboring molecule. These observations provide experimental evidence for the role of states with significant charge-transfer character which facilitate the singlet fission process in pentacene. Our work both provides new insight into the singlet fission mechanism in pentacene and demonstrates the utility of structurally-sensitive time-resolved spectroscopic techniques in monitoring ultrafast processes. 12. Charge transfer through single molecule contacts: How reliable are rate descriptions? Directory of Open Access Journals (Sweden) Denis Kast 2011-08-01 Full Text Available Background: The trend for the fabrication of electrical circuits with nanoscale dimensions has led to impressive progress in the field of molecular electronics in the last decade. However, a theoretical description of molecular contacts as the building blocks of future devices is challenging, as it has to combine the properties of Fermi liquids in the leads with charge and phonon degrees of freedom on the molecule. Outside of ab initio schemes for specific set-ups, generic models reveal the characteristics of transport processes. Particularly appealing are descriptions based on transfer rates successfully used in other contexts such as mesoscopic physics and intramolecular electron transfer. However, a detailed analysis of this scheme in comparison with numerically exact solutions is still elusive.Results: We show that a formulation in terms of transfer rates provides a quantitatively accurate description even in domains of parameter space where strictly it is expected to fail, e.g., at lower temperatures. Typically, intramolecular phonons are distributed according to a voltage driven steady state that can only roughly be captured by a thermal distribution with an effective elevated temperature (heating. An extension of a master equation for the charge–phonon complex, to effectively include the impact of off-diagonal elements of the reduced density matrix, provides very accurate solutions even for stronger electron–phonon coupling.Conclusion: Rate descriptions and master equations offer a versatile model to describe and understand charge transfer processes through molecular junctions. Such methods are computationally orders of magnitude less expensive than elaborate numerical simulations that, however, provide exact solutions as benchmarks. Adjustable parameters obtained, e.g., from ab initio calculations allow for the treatment of various realizations. Even though not as rigorously formulated as, e.g., nonequilibrium Green’s function 13. Charge Transfer Processes in Collisions of Si4+ Ions with He Atoms at Intermediate Energies Science.gov (United States) Suzuki, R.; Watanabe, A.; Sato, H.; Gu, J. P.; Hirsch, G.; Buenker, R. J.; Kimura, M.; Stancil, P. C. Charge transfer in collisions of Si4+ ions with He atoms below 100 keV/u is studied by using a molecular orbital representation within both the semiclassical and quantal representations. Single transfer reaction Si4++He →Si3++He+ has been studied by a number of theoretical investigations. In addition to the reaction (1), the first semiclassical MOCC calculations are performed for the double transfer channel Si4++HE→Si2++He2+ Nine molecular states that connect both with single and double electron transfer processes are considered in the present model. Electronic states and corresponding couplings are determined by the multireference single- and double- excitation configuration interaction method. The present cross sections tie well with the earlier calculations of Stancil et al., Phys. Rev. A 55, 1064 (1997) at lower energies, but show a rather different magnitude from those of Bacchus-Montabonel and Ceyzeriat, Phys. Rev. A 58, 1162 (1998). The present rate constant is found to be significantly different from the experimental finding of Fang and Kwong, Phys. Rev. A 59, 342 (1996) at 4,600 K, and hence does not support the experiment. 14. 129I Moessbauer spectroscopic study of several n-σ charge-transfer complexes of iodine with thioethers International Nuclear Information System (INIS) Sakai, Hiroshi; Matsuyama, Tomochika; Maeda, Yutaka 1986-01-01 129 I Moessbauer studies have been made of n-σ charge-transfer complexes of iodine with thioethers, such as thiane, 1,4-oxathiane, and 1,4-dithiane. The spectra of these complexes consist of two sets of quadrupole octets, corresponding to the bridging and terminal iodine atoms. The transferred charges from the thioethers are localized on the terminal iodine atoms, and the bridging iodine atoms have slightly positive charges. This result can be well explained in terms of a covalent bond between the sulfur and bridging iodine atoms or the MO treatment of a delocalized three-center four-electron bonding. The contributions of the dative structure to the ground state are estimated to be 36, 28, and 24 % for thiane-iodine, 1,4-oxathiane-iodine, and 1,4-dithiane-iodine respectively. The nature of the charge-transfer bond is discussed in comparison with amine-iodine complexes. (author) 15. Spectroscopic studies of charge transfer complexes of some amino aromatic donors with some acceptors International Nuclear Information System (INIS) Al-Ani, S.S. 1989-01-01 Charge transfer (C.T.) complexes are the products of the weak reversible interactions between electron donors and electron acceptors. Sixteen novel C.T. complexes were studied and discussed. These complexes were formed from aromatic electron donors with various electron acceptors in absolute ethyl alcohol at 20 0 C. Electronic absorption spectra of these complexes and their donors and acceptors were taken. New charge transfer absorption bands appeared for these complexes in the UV-VIS region. The donors used are tetramethyl diamino benzophenone, P-amino-N:N-dimethyl aniline, tetramethyl-diamino-diphenylmethane, P-amino-azobenzene and benzidine, while the acceptors are iodine, bromine, picric acid, 2,4-dinitrophenol, trifluoroacetic acid and trichloroacetic acid. The results showed a disappearance of some donors and acceptors absorption bands. The energy of C.T. bands were calculated from which the ionization potentials of donors were obtained. The results showed that energies of C.T. Bands for complexes of a given donor with a series of acceptors are very similar. Some C.T. complexes showed low value of energy and high values of electrical conductivity. These are ionic complexes rather than molecular ones. 4 tabs.; 2 figs.; 99 refs 16. Observation of excited state charge transfer with fs/ps-CARS Energy Technology Data Exchange (ETDEWEB) Blom, Alex Jason [Iowa State Univ., Ames, IA (United States) 2009-01-01 Excited state charge transfer processes are studied using the fs/ps-CARS probe technique. This probe allows for multiplexed detection of Raman active vibrational modes. Systems studied include Michler's Ketone, Coumarin 120, 4-dimethylamino-4'-nitrostilbene, and several others. The vibrational spectrum of the para di-substituted benzophenone Michler's Ketone in the first excited singlet state is studied for the first time. It is found that there are several vibrational modes indicative of structural changes of the excited molecule. A combined experimental and theoretical approach is used to study the simplest 7-amino-4-methylcoumarin, Coumarin 120. Vibrations observed in FTIR and spontaneous Raman spectra are assigned using density functional calculations and a continuum solvation model is used to predict how observed modes are affected upon inclusion of a solvent. The low frequency modes of the excited state charge transfer species 4-dimethylamino-4{prime}-nitrostilbene are studied in acetonitrile. Results are compared to previous work on this molecule in the fingerprint region. Finally, several partially completed projects and their implications are discussed. These include the two photon absorption of Coumarin 120, nanoconfinement in cyclodextrin cavities and sensitization of titania nanoparticles. 17. Experimental and modeling study on charge storage/transfer mechanism of graphene-based supercapacitors Science.gov (United States) Ban, Shuai; Jing, Xie; Zhou, Hongjun; Zhang, Lei; Zhang, Jiujun 2014-12-01 A symmetrical graphene-based supercapacitor is constructed for studying the charge-transfer mechanism within the graphene-based electrodes using both experiment measurements and molecular simulation. The in-house synthesized graphene is characterized by XRD, SEM and BET measurements for morphology and surface area. It is observed that the electric capacity of graphene electrode can be reduced by both high internal resistance and limited mass transfer. Computer modeling is conducted at the molecular level to characterize the diffusion behavior of electrolyte ions to the interior of electrode with emphasis on the unique 2D confinement imposed by graphene layers. Although graphene powder poses a moderate internal surface of 400 m2 g-1, the capacitance performance of graphene electrode can be as good as that of commercial activated carbon which has an overwhelming surface area of 1700 m2 g-1. An explanation to this abnormal correlation is that graphene material has an intrinsic capability of adaptively reorganizing its microporous structure in response to intercalation of ions and immergence of electrolyte solvent. The accessible surface of graphene is believed to be dramatically enlarged for ion adsorption during the charging process of capacitor. 18. Excitation and charge transfer in low-energy hydrogen atom collisions with neutral oxygen Science.gov (United States) Barklem, P. S. 2018-02-01 Excitation and charge transfer in low-energy O+H collisions is studied; it is a problem of importance for modelling stellar spectra and obtaining accurate oxygen abundances in late-type stars including the Sun. The collisions have been studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model. The method has been extended to include configurations involving excited states of hydrogen using an estimate for the two-electron transition coupling, but this extension was found to not lead to any remarkably high rates. Rate coefficients are calculated for temperatures in the range 1000-20 000 K, and charge transfer and (de)excitation processes involving the first excited S-states, 4s.5So and 4s.3So, are found to have the highest rates. Data are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/vizbin/qcat?J/A+A/610/A57. The data are also available at http://https://github.com/barklem/public-data 19. Charge Transfer Mechanism in Titanium-Doped Microporous Silica for Photocatalytic Water-Splitting Applications Directory of Open Access Journals (Sweden) Wendi Sapp 2016-02-01 Full Text Available Solar energy conversion into chemical form is possible using artificial means. One example of a highly-efficient fuel is solar energy used to split water into oxygen and hydrogen. Efficient photocatalytic water-splitting remains an open challenge for researchers across the globe. Despite significant progress, several aspects of the reaction, including the charge transfer mechanism, are not fully clear. Density functional theory combined with density matrix equations of motion were used to identify and characterize the charge transfer mechanism involved in the dissociation of water. A simulated porous silica substrate, using periodic boundary conditions, with Ti4+ ions embedded on the inner pore wall was found to contain electron and hole trap states that could facilitate a chemical reaction. A trap state was located within the silica substrate that lengthened relaxation time, which may favor a chemical reaction. A chemical reaction would have to occur within the window of photoexcitation; therefore, the existence of a trapping state may encourage a chemical reaction. This provides evidence that the silica substrate plays an integral part in the electron/hole dynamics of the system, leading to the conclusion that both components (photoactive materials and support of heterogeneous catalytic systems are important in optimization of catalytic efficiency. 20. K-shell-hole production, multiple-hole production, charge transfer, and antisymmetry International Nuclear Information System (INIS) 1980-01-01 In calculating K-shell-hole production when an ion collides with an atom, account must be taken of the fact that processes involving electrons other than the K-shell electron can occur. For example, after making a K-shell hole an L-shell electron may be knocked into it, or an L-shell vacancy may be produced and the K-shell electron promoted to that vacancy in the ''Fermi sea'' of the target-atom orbitals. In 1973 a theorem was proved by one of the present authors demonstrating that all these multielectron processes cancel in an independent-particle model for the target atom. In this paper it is shown that the same thing occurs for hole production by charge transfer to the ion. The authors demonstrate that multihole production does not obey this simple rule and that the probability for multihole production is not the product of independent single-electron probabilities. The correct expressions that should be used for these processes are given, together with new results for charge-transfer processes accompanied by hole production 1. Theory of interfacial charge-transfer complex photophysics in π-conjugated polymer-fullerene blends Science.gov (United States) Aryanpour, K.; Psiachos, D.; Mazumdar, S. 2010-03-01 We present a theory of the electronic structure and photophysics of 1:1 blends of derivatives of polyparaphenylenevinylene and fullerenes [1]. Within the same Coulomb-correlated Hamiltonian applied previously to interacting chains of single-component π-conjugated polymers [2], we find an exciplex state that occurs below the polymer's optical exciton. Weak absorption from the ground state occurs to the exciplex. We explain transient photoinduced absorptions in the blend [3], observed for both above-gap and below-gap photoexcitations, within our theory. Photoinduced absorptions for above-gap photoexcitation are from the optical exciton as well as the exciplex, while for below-gap photoexcitation induced absorptions are from the exciplex alone. In neither case are free polarons generated in the time scale of the experiment. Importantly, the photophysics of films of single-component π-conjugated polymers and blends can both be understood by extending Mulliken's theory of ground state charge-transfer to the case of excited state charge-transfer. [1] K. Aryanpour, D. Psiachos, and S. Mazumdar, arXiv:0908.0366 [2] D. Psiachos and S. Mazumdar, Phys. Rev. B. 79 155106 (2009) [3] T. Drori et al., Phys. Rev. Lett. 101, 037402 (2008) 2. Momentum transfer theory of non-conservative charged particle transport in crossed electric and magnetic fields International Nuclear Information System (INIS) Vrhovac, S.B.; Petrovic, Z.Lj. 1995-01-01 Momentum - transfer approximation is applied to momentum and energy balance equations describing reacting particle swarms in gases in crossed electric and magnetic fields. Transport coefficients of charged particles undergoing both inelastic and reactive, non-particle-conserving collisions with a gas of neutral molecules are calculated. Momentum - transfer theory (MTT) has been developed mainly by Robson and collaborators. It has been applied to a single reactive gas and mixtures of reactive gases in electric field only. MTT has also been applied in crossed electric and magnetic fields recently and independently of our work but the reactive collisions were not considered. Consider a swarm of electrons of charge e and mass m moving with velocity rvec v through a neutral gas under the influence of an applied electric rvec E and magnetic rvec B field. The collision processes which we shall investigate are limited to elastic, inelastic and reactive collisions of electrons with gas molecules. Here we interpret reactive collisions as collisions which produce change in number of the swarm particles. Reactive collisions involve creation (ionization by electron impact) or loss (electron attachment) of swarm particles. We consider only single ionization in approximation of the mass ratio m/m 0 0 are masses of electrons and neutral particles, respectively. We assume that the stage of evolution of the swarm is the hydrodynamic limit (HDL). In HDL, the space - time dependence of all properties is carried by the number density n of swarm particles 3. Spectroscopic and theoretical investigations on intramolecular charge transfer phenomenon in 1-3-dioxolane derivative Science.gov (United States) Zhang, Zhiyong; Zhang, Zhongzhi; Luo, Yijing; Sun, Shanshan; Zhang, Guangqing 2018-02-01 High fluorescence quantum yield (FQY) and large Stokes shift (SS) cannot be easily achieved simultaneously by traditional PICT or TICT fluorescent probe. However, an 1-3-dioxolane derivative named 5-methyl-8,9-dihydro-5H-[1,3]dioxolo[4,5-b]carbazol-6(7H)-one (MDDCO) features both high FQY and large SS. The purpose of this study is to search the mechanism behind this phenomenon by theoretical method. Simulated structure changes and charge transfer suggest ICT process in MDDCO is similar to PLICT (Planarized Intramolecular Charge Transfer) process. Calculated UV-Vis spectra and fluorescence spectra show that PLICT-like state (S1 state) of MDDCO leads to large SS. Computed transient-absorption spectra and radiative decay rates indicate that PLICT-like state is key factor for high FQY of MDDCO. These findings suggest that PLICT-like state in 1,3-dioxolane derivatives can achieve both large SS and high FQY, which presents a new method for high-performance fluorescent probe design. 4. Observation of excited state charge transfer with fs/ps-CARS International Nuclear Information System (INIS) Blom, Alex Jason 2009-01-01 Excited state charge transfer processes are studied using the fs/ps-CARS probe technique. This probe allows for multiplexed detection of Raman active vibrational modes. Systems studied include Michler's Ketone, Coumarin 120, 4-dimethylamino-4(prime)-nitrostilbene, and several others. The vibrational spectrum of the para di-substituted benzophenone Michler's Ketone in the first excited singlet state is studied for the first time. It is found that there are several vibrational modes indicative of structural changes of the excited molecule. A combined experimental and theoretical approach is used to study the simplest 7-amino-4-methylcoumarin, Coumarin 120. Vibrations observed in FTIR and spontaneous Raman spectra are assigned using density functional calculations and a continuum solvation model is used to predict how observed modes are affected upon inclusion of a solvent. The low frequency modes of the excited state charge transfer species 4-dimethylamino-4(prime)-nitrostilbene are studied in acetonitrile. Results are compared to previous work on this molecule in the fingerprint region. Finally, several partially completed projects and their implications are discussed. These include the two photon absorption of Coumarin 120, nanoconfinement in cyclodextrin cavities and sensitization of titania nanoparticles 5. Frenkel-Charge-Transfer exciton intermixing theory for molecular crystals with two isolated Frenkel exciton states. Science.gov (United States) We develop an analytical theory for the intra-intermolecular exciton intermixing in periodic 1D chains of planar organic molecules with two isolated low-lying Frenkel exciton states, typical of copper phthalocyanine (CuPc) and other transition metal phthalocyanine molecules. We formulate the Hamiltonian and use the exact Bogoliubov diagonalization procedure to derive the eigen energy spectrum for the two lowest intramolecular Frenkel excitons coupled to the intermolecular charge transfer (CT) exciton state. By comparing our theoretical spectrum with available experimental CuPc absorption data, we obtain the parameters of the Frenkel-CT exciton intermixing in CuPc thin films. The two Frenkel exciton states here are spaced apart by 0.26 eV, and the charge transfer exciton state is 50 meV above the lowest Frenkel exciton. Both Frenkel excitons are strongly mixed with the CT exciton, showing the coupling constant 0.17 eV in agreement with earlier electron transport experiments. Our results can be used for the proper interpretation of the physical properties of crystalline phthalocyanines. DOE-DE-SC0007117 (I.B.), UNC-GA ROI Grant (A.P.). 6. Differential charge-transfer cross sections for systems with energetically degenerate or near-degenerate channels International Nuclear Information System (INIS) Nguyen, H.; Bredy, R.; Camp, H.A.; DePaola, B.D.; Awata, T. 2004-01-01 Resolution plays a vital role in spectroscopic studies. In the usual recoil-ion momentum spectroscopy (RIMS), Q-value resolution is relied upon to distinguish between different collision channels: The better the Q-value resolution, the better one is able to resolve energetically similar channels. Although traditional COLTRIMS greatly improves Q-value resolution by cooling the target and thus greatly reducing the initial target momentum spread, the resolution of the technique is still limited by target temperature. However, with the recent development in RIMS, namely, magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) superior recoil ion momentum resolution as well as charge transfer measurements with laser excited targets have become possible. Through MOTRIMS, methods for the measurements of target excited state fraction and kinematically complete relative charge transfer cross sections have been developed, even for some systems having energetically degenerate or nearly degenerate channels. In the present work, the systems of interest having energy degeneracies or near degeneracies are Rb + , K + , and Li + colliding with trapped Rb(5l), where l=s and p 7. Real-time observation of intersystem crossing induced by charge recombination during bimolecular electron transfer reactions KAUST Repository Alsam, Amani Abdu 2016-09-21 Real-time probing of intersystem crossing (ISC) and triplet-state formation after photoinduced electron transfer (ET) is a particularly challenging task that can be achieved by time-resolved spectroscopy with broadband capability. Here, we examine the mechanism of charge separation (CS), charge recombination (CR) and ISC of bimolecular photoinduced electron transfer (PET) between poly[(9,9-di(3,3′-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and dicyanobenzene (DCB) using time-resolved spectroscopy. PET from PFN to DCB is confirmed by monitoring the transient absorption (TA) and infrared spectroscopic signatures for the radical ion pair (DCB─•-PFN+•). In addition, our time-resolved results clearly demonstrate that CS takes place within picoseconds followed by CR within nanoseconds. The ns-TA data exhibit the clear spectroscopic signature of PFN triplet-triplet absorption, induced by the CR of the radical ion pairs (DCB─•-PFN+•). As a result, the triplet state of PFN (3PFN) forms and subsequently, the ground singlet state is replenished within microseconds. © 2016 8. Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems Energy Technology Data Exchange (ETDEWEB) Van Tassle, Aaron Justin [Univ. of California, Berkeley, CA (United States) 2006-01-01 This dissertation describes the development andimplementation of a visible/near infrared pump/mid-infrared probeapparatus. Chapter 1 describes the background and motivation ofinvestigating optically induced structural dynamics, paying specificattention to solvation and the excitation selection rules of highlysymmetric molecules such as carotenoids. Chapter 2 describes thedevelopment and construction of the experimental apparatus usedthroughout the remainder of this dissertation. Chapter 3 will discuss theinvestigation of DCM, a laser dye with a fluorescence signal resultingfrom a charge transfer state. By studying the dynamics of DCM and of itsmethyl deuterated isotopomer (an otherwise identical molecule), we areable to investigate the origins of the charge transfer state and provideevidence that it is of the controversial twisted intramolecular (TICT)type. Chapter 4 introduces the use of two-photon excitation to the S1state, combined with one-photon excitation to the S2 state of thecarotenoid beta-apo-8'-carotenal. These 2 investigations show evidencefor the formation of solitons, previously unobserved in molecular systemsand found only in conducting polymers Chapter 5 presents an investigationof the excited state dynamics of peridinin, the carotenoid responsiblefor the light harvesting of dinoflagellates. This investigation allowsfor a more detailed understanding of the importance of structuraldynamics of carotenoids in light harvesting. 9. Heat exchange between a microparticle and plasma. Contribution of charge transfer processes International Nuclear Information System (INIS) Uglov, A.A.; Gnedovets, A.G. 1983-01-01 Heat- and mass-transfer in interaction of a microparticle with a dense plasma have been considered analytically. At that, calculation methods developed as applied to probe diagnostics of slightly ionized plasma are also used in the case of relatively high degrees of ionization, at which heat flows of plasma charged particles Qe and Qi become comparable with molecular ones. High efficiency of energy transfer during electron and ion collisions with a microparticle is due to the following: 1) effective cross section of ion collision with a microparticle, which acquires in a quasineutral plasma the potential phisub(f) < 0, surpasses the geometric one; the maximum contribution of electron and ion constituent is achieved when the cross section ion collisions with a microparticle is linearly connected with its potential, 2) with a charged microparticle electrons from distribution function ''tail'' collide, their energy exceeds potential barrier near the surface and, consequently, the mean heat energy; 3) besides the energy of a microparticle thermal movement during electron recombination and ion neutralization on its surface the heat Qsub(e) and Qsub(i), which considerably exceed the heat of molecular adsorption and mean heat energy of plasma particles at kT approximately 1 eV, are transmitted to the microparticle 10. Electronic properties of Fe charge transfer complexes – A combined experimental and theoretical approach International Nuclear Information System (INIS) Ferreira, Hendrik; Eschwege, Karel G. von; Conradie, Jeanet 2016-01-01 Highlights: • Experimental and computational study of Fe II -phen, -bpy & -tpy compleesx. • Close correlations between experimental redox and spectral, and computational data. • Computational methods fast-track DSSC research. - Abstract: Dye-sensitized solar cell technology holds huge potential in renewable electricity generation of the future. Due to demand urgency, ways need to be explored to reduce research time and cost. Against this background, quantum computational chemistry is illustrated to be a reliable tool at the onset of studies in this field, simulating charge transfer, spectral (solar energy absorbed) and electrochemical (ease by which electrons may be liberated) tuning of related photo-responsive dyes. Comparative experimental and theoretical DFT studies were done under similar conditions, involving an extended series of electrochemically altered phenanthrolines, bipyridyl and terpyridyl complexes of Fe II . Fe II/III oxidation waves vary from 0.363 V for tris(3,6-dimethoxybipyridyl)Fe II to 0.894 V (versus Fc/Fc + ) for the 5-nitrophenanthroline complex. Theoretical DFT computed ionization potentials in the bipyridyl sub-series achieved an almost 100% linear correlation with experimental electrochemical oxidation potentials, while the phenanthroline sub-series gave R 2 = 0.95. Apart from the terpyridyl complex which accorded an almost perfect match, in general, TDDFT oscillators were computed at slightly lower energies than what was observed experimentally, while molecular HOMO and LUMO renderings reveal desired complexes with directional charge transfer propensities. 11. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes Science.gov (United States) Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G. 2015-10-01 Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation. 12. Microgravity and Charge Transfer in the Neuronal Membrane: Implications for Computational Neurobiology Science.gov (United States) Wallace, Ron 1995-01-01 Evidence from natural and artificial membranes indicates that the neural membrane is a liquid crystal. A liquid-to-gel phase transition caused by the application of superposed electromagnetic fields to the outer membrane surface releases spin-correlated electron pairs which propagate through a charge transfer complex. The propagation generates Rydberg atoms in the lipid bilayer lattice. In the present model, charge density configurations in promoted orbitals interact as cellular automata and perform computations in Hilbert space. Due to the small binding energies of promoted orbitals, their automata are highly sensitive to microgravitational perturbations. It is proposed that spacetime is classical on the Rydberg scale, but formed of contiguous moving segments, each of which displays topological equivalence. This stochasticity is reflected in randomized Riemannian tensor values. Spacetime segments interact with charge automata as components of a computational process. At the termination of the algorithm, an orbital of high probability density is embedded in a more stabilized microscopic spacetime. This state permits the opening of an ion channel and the conversion of a quantum algorithm into a macroscopic frequency code. 13. Application of double-hybrid density functionals to charge transfer in N-substituted pentacenequinones. Science.gov (United States) Sancho-García, J C 2012-05-07 A set of N-heteroquinones, deriving from oligoacenes, have been recently proposed as n-type organic semiconductors with high electron mobilities in thin-film transistors. Generally speaking, this class of compounds self-assembles in neighboring π-stacks linked by weak hydrogen bonds. We aim at theoretically characterizing here the sequential charge transport (hopping) process expected to take place across these arrays of molecules. To do so, we need to accurately address the preferred packing of these materials simultaneously to single-molecule properties related to charge-transfer events, carefully employing dispersion-corrected density functional theory methods to accurately extract the key molecular parameters governing this phenomenon at the nanoscale. This study confirms the great deal of interest around these compounds, since controlled functionalization of model molecules (i.e., pentacene) allows to efficiently tune the corresponding charge mobilities, and the capacity of modern quantum-chemical methods to predict it after rationalizing the underlying structure-property relationships. 14. Hydrated proton and hydroxide charge transfer at the liquid/vapor interface of water Energy Technology Data Exchange (ETDEWEB) Soniat, Marielle; Rick, Steven W., E-mail: srick@uno.edu [Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148 (United States); Kumar, Revati [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70808 (United States) 2015-07-28 The role of the solvated excess proton and hydroxide ions in interfacial properties is an interesting scientific question with applications in a variety of aqueous behaviors. The role that charge transfer (CT) plays in interfacial behavior is also an unsettled question. Quantum calculations are carried out on clusters of water with an excess proton or a missing proton (hydroxide) to determine their CT. The quantum results are applied to analysis of multi-state empirical valence bond trajectories. The polyatomic nature of the solvated excess proton and hydroxide ion results in directionally dependent CT, depending on whether a water molecule is a hydrogen bond donor or acceptor in relation to the ion. With polyatomic molecules, CT also depends on the intramolecular bond distances in addition to intermolecular distances. The hydrated proton and hydroxide affect water’s liquid/vapor interface in a manner similar to monatomic ions, in that they induce a hydrogen-bonding imbalance at the surface, which results in charged surface waters. This hydrogen bond imbalance, and thus the charged waters at the surface, persists until the ion is at least 10 Å away from the interface. 15. Large impact of reorganization energy on photovoltaic conversion due to interfacial charge-transfer transitions. Science.gov (United States) Fujisawa, Jun-ichi 2015-05-14 Interfacial charge-transfer (ICT) transitions are expected to be a novel charge-separation mechanism for efficient photovoltaic conversion featuring one-step charge separation without energy loss. Photovoltaic conversion due to ICT transitions has been investigated using several TiO2-organic hybrid materials that show organic-to-inorganic ICT transitions in the visible region. In applications of ICT transitions to photovoltaic conversion, there is a significant problem that rapid carrier recombination is caused by organic-inorganic electronic coupling that is necessary for the ICT transitions. In order to solve this problem, in this work, I have theoretically studied light-to-current conversions due to the ICT transitions on the basis of the Marcus theory with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. An apparent correlation between the reported incident photon-to-current conversion efficiencies (IPCE) and calculated reorganization energies was clearly found, in which the IPCE increases with decreasing the reorganization energy consistent with the Marcus theory in the inverted region. This activation-energy dependence was systematically explained by the equation formulated by the Marcus theory based on a simple excited-state kinetic scheme. This result indicates that the reduction of the reorganization energy can suppress the carrier recombination and enhance the IPCE. The reorganization energy is predominantly governed by the structural change in the chemical-adsorption moiety between the ground and ICT excited states. This work provides crucial knowledge for efficient photovoltaic conversion due to ICT transitions. 16. Improper ferroelectric polarization in a perovskite driven by intersite charge transfer and ordering Science.gov (United States) Chen, Wei-Tin; Wang, Chin-Wei; Wu, Hung-Cheng; Chou, Fang-Cheng; Yang, Hung-Duen; Simonov, Arkadiy; Senn, M. S. 2018-04-01 It is of great interest to design and make materials in which ferroelectric polarization is coupled to other order parameters such as lattice, magnetic, and electronic instabilities. Such materials will be invaluable in next-generation data storage devices. Recently, remarkable progress has been made in understanding improper ferroelectric coupling mechanisms that arise from lattice and magnetic instabilities. However, although theoretically predicted, a compact lattice coupling between electronic and ferroelectric (polar) instabilities has yet to be realized. Here we report detailed crystallographic studies of a perovskite HgAMn3A'Mn4BO12 that is found to exhibit a polar ground state on account of such couplings that arise from charge and orbital ordering on both the A'- and B-sites, which are themselves driven by a highly unusual MnA '-MnB intersite charge transfer. The inherent coupling of polar, charge, orbital, and hence magnetic degrees of freedom make this a system of great fundamental interest, and demonstrating ferroelectric switching in this and a host of recently reported hybrid improper ferroelectrics remains a substantial challenge. 17. Hydrated proton and hydroxide charge transfer at the liquid/vapor interface of water International Nuclear Information System (INIS) Soniat, Marielle; Rick, Steven W.; Kumar, Revati 2015-01-01 The role of the solvated excess proton and hydroxide ions in interfacial properties is an interesting scientific question with applications in a variety of aqueous behaviors. The role that charge transfer (CT) plays in interfacial behavior is also an unsettled question. Quantum calculations are carried out on clusters of water with an excess proton or a missing proton (hydroxide) to determine their CT. The quantum results are applied to analysis of multi-state empirical valence bond trajectories. The polyatomic nature of the solvated excess proton and hydroxide ion results in directionally dependent CT, depending on whether a water molecule is a hydrogen bond donor or acceptor in relation to the ion. With polyatomic molecules, CT also depends on the intramolecular bond distances in addition to intermolecular distances. The hydrated proton and hydroxide affect water’s liquid/vapor interface in a manner similar to monatomic ions, in that they induce a hydrogen-bonding imbalance at the surface, which results in charged surface waters. This hydrogen bond imbalance, and thus the charged waters at the surface, persists until the ion is at least 10 Å away from the interface 18. Simulation of charge transfer and orbital rehybridization in molecular and condensed matter systems Science.gov (United States) Nistor, Razvan A. The mixing and shifting of electronic orbitals in molecules, or between atoms in bulk systems, is crucially important to the overall structure and physical properties of materials. Understanding and accurately modeling these orbital interactions is of both scientific and industrial relevance. Electronic orbitals can be perturbed in several ways. Doping, adding or removing electrons from systems, can change the bond-order and the physical properties of certain materials. Orbital rehybridization, driven by either thermal or pressure excitation, alters the short-range structure of materials and changes their long-range transport properties. Macroscopically, during bond formation, the shifting of electronic orbitals can be interpreted as a charge transfer phenomenon, as electron density may pile up around, and hence, alter the effective charge of, a given atom in the changing chemical environment. Several levels of theory exist to elucidate the mechanisms behind these orbital interactions. Electronic structure calculations solve the time-independent Schrodinger equation to high chemical accuracy, but are computationally expensive and limited to small system sizes and simulation times. Less fundamental atomistic calculations use simpler parameterized functional expressions called force-fields to model atomic interactions. Atomistic simulations can describe systems and time-scales larger and longer than electronic-structure methods, but at the cost of chemical accuracy. In this thesis, both first-principles and phenomenological methods are addressed in the study of several encompassing problems dealing with charge transfer and orbital rehybridization. Firstly, a new charge-equilibration method is developed that improves upon existing models to allow next-generation force-fields to describe the electrostatics of changing chemical environments. Secondly, electronic structure calculations are used to investigate the doping dependent energy landscapes of several high 19. Intra-molecular Charge Transfer and Electron Delocalization in Non-fullerene Organic Solar Cells Energy Technology Data Exchange (ETDEWEB) Wu, Qinghe [Department of Chemistry, Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China; Zhao, Donglin [Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States; Goldey, Matthew B. [Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States; Filatov, Alexander S. [Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States; Sharapov, Valerii [Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States; Colón, Yamil J. [Institute for Molecular Engineering, Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States; Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States; Cai, Zhengxu [Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States; Chen, Wei [Institute for Molecular Engineering, Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States; Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States; de Pablo, Juan [Institute for Molecular Engineering, Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States; Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States; Galli, Giulia [Institute for Molecular Engineering, Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue, Lemont, Illinois 60439, United States; Institute for Molecular Engineering, The University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States; Yu, Luping [Department of Chemistry, The James Franck Institute, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States 2018-03-02 Two types of electron acceptors were synthesized by coupling two kinds of electron-rich cores with four equivalent perylene diimides (PDIs) at the a position. With fully aromatic cores, TPB and TPSe have pi-orbitals spread continuously over the whole aromatic conjugated backbone, unlike TPC and TPSi, which contain isolated PDI units due to the use of a tetrahedron carbon or silicon linker. Density functional theory calculations of the projected density of states showed that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) for TPB are localized in separate regions of space. Further, the LUMO of TPB shows a greater contribution from the orbitals belonging to the connective core of the molecules than that of TPC. Overall, the properties of the HOMO and LUMO point at increased intra-molecular delocalization of negative charge carriers for TPB and TPSe than for TPC and TPSi and hence at a more facile intra-molecular charge transfer for the former. The film absorption and emission spectra showed evidences for the inter -molecular electron delocalization in TPB and TPSe, which is consistent with the network structure revealed by X-ray diffraction studies on single crystals of TPB. These features benefit the formation of charge transfer states and/or facilitate charge transport. Thus, higher electron mobility and higher charge dissociation probabilities under J(sc) condition were observed in blend films of TPB:PTB7-Th and TPSe:PTB7-Th than those in TPC:PTB7Th and TPSi:PTB7-Th blend films. As a result, the J(sc) and fill factor values of 15.02 mA/cm(2), 0.58 and 14.36 mA/cm(2), 0.55 for TPB- and TPSe-based solar cell are observed, whereas those for TPC and TPSi are 11.55 mA/cm2, 0.47 and 10.35 mA/cm(2), 0.42, respectively. 20. Heat transfer performance of a pulsating heat pipe charged with acetone-based mixtures Science.gov (United States) Wang, Wenqing; Cui, Xiaoyu; Zhu, Yue 2017-06-01 Pulsating heat pipes (PHPs) are used as high efficiency heat exchangers, and the selection of working fluids in PHPs has a great impact on the heat transfer performance. This study investigates the thermal resistance characteristics of the PHP charged with acetone-based binary mixtures, where deionized water, methanol and ethanol were added to and mixed with acetone, respectively. The volume mixing ratios were 2:1, 4:1 and 7:1, and the heating power ranged from 10 to 100 W with filling ratios of 45, 55, 62 and 70%. At a low filling ratio (45%), the zeotropic characteristics of the binary mixtures have an influence on the heat transfer performance of the PHP. Adding water, which has a substantially different boiling point compared with that of acetone, can significantly improve the anti-dry-out ability inside the PHP. At a medium filling ratio (55%), the heat transfer performance of the PHP is affected by both phase transition characteristics and physical properties of working fluids. At high heating power, the thermal resistance of the PHP with acetone-water mixture is between that with pure acetone and pure water, whereas the thermal resistance of the PHP with acetone-methanol and acetone-ethanol mixtures at mixing ratios of 2:1 and 4:1 is less than that with the corresponding pure fluids. At high filling ratios (62 and 70%), the heat transfer performance of the PHP is mainly determined by the properties of working fluids that affects the flow resistance. Thus, the PHP with acetone-methanol and acetone-ethanol mixtures that have a lower flow resistance shows better heat transfer performance than that with acetone-water mixture. 1. Molecular Engineering for Enhanced Charge Transfer in Thin-Film Photoanode. Science.gov (United States) Kim, Jeong Soo; Kim, Byung-Man; Kim, Un-Young; Shin, HyeonOh; Nam, Jung Seung; Roh, Deok-Ho; Park, Jun-Hyeok; Kwon, Tae-Hyuk 2017-10-11 We developed three types of dithieno[3,2-b;2',3'-d]thiophene (DTT)-based organic sensitizers for high-performance thin photoactive TiO 2 films and investigated the simple but powerful molecular engineering of different types of bonding between the triarylamine electron donor and the conjugated DTT π-bridge by the introduction of single, double, and triple bonds. As a result, with only 1.3 μm transparent and 2.5-μm TiO 2 scattering layers, the triple-bond sensitizer (T-DAHTDTT) shows the highest power conversion efficiency (η = 8.4%; V OC = 0.73 V, J SC = 15.4 mA·cm -2 , and FF = 0.75) in an iodine electrolyte system under one solar illumination (AM 1.5, 1000 W·m -2 ), followed by the single-bond sensitizer (S-DAHTDTT) (η = 7.6%) and the double-bond sensitizer (D-DAHTDTT) (η = 6.4%). We suggest that the superior performance of T-DAHTDTT comes from enhanced intramolecular charge transfer (ICT) induced by the triple bond. Consequently, T-DAHTDTT exhibits the most active photoelectron injection and charge transport on a TiO 2 film during operation, which leads to the highest photocurrent density among the systems studied. We analyzed these correlations mainly in terms of charge injection efficiency, level of photocharge storage, and charge-transport kinetics. This study suggests that the molecular engineering of a triple bond between the electron donor and the π-bridge of a sensitizer increases the performance of dye-sensitized solar cell (DSC) with a thin photoactive film by enhancing not only J SC through improved ICT but also V OC through the evenly distributed sensitizer surface coverage. 2. Vibrational inelastic and charge transfer processes in H++H2 system: An ab initio study Science.gov (United States) Amaran, Saieswari; Kumar, Sanjay 2007-12-01 State-resolved differential cross sections, total and integral cross sections, average vibrational energy transfer, and the relative probabilities are computed for the H++H2 system using the newly obtained ab initio potential energy surfaces at the full CI/cc-pVQZ level of accuracy which allow for both the direct vibrational inelastic and the charge transfer processes. The quantum dynamics is treated within the vibrational close-coupling infinite-order-sudden approximation approach using the two ab initio quasidiabatic potential energy surfaces. The computed collision attributes for both the processes are compared with the available state-to-state scattering experiments at Ec.m.=20eV. The results are in overall good agreement with most of the observed scattering features such as rainbow positions, integral cross sections, and relative vibrational energy transfers. A comparison with the earlier theoretical study carried out on the semiempirical surfaces (diatomics in molecules) is also made to illustrate the reliability of the potential energy surfaces used in the present work. 3. Regressed relations for forced convection heat transfer in a direct injection stratified charge rotary engine Science.gov (United States) Lee, Chi M.; Schock, Harold J. 1988-01-01 Currently, the heat transfer equation used in the rotary combustion engine (RCE) simulation model is taken from piston engine studies. These relations have been empirically developed by the experimental input coming from piston engines whose geometry differs considerably from that of the RCE. The objective of this work was to derive equations to estimate heat transfer coefficients in the combustion chamber of an RCE. This was accomplished by making detailed temperature and pressure measurements in a direct injection stratified charge (DISC) RCE under a range of conditions. For each specific measurement point, the local gas velocity was assumed equal to the local rotor tip speed. Local physical properties of the fluids were then calculated. Two types of correlation equations were derived and are described in this paper. The first correlation expresses the Nusselt number as a function of the Prandtl number, Reynolds number, and characteristic temperature ratio; the second correlation expresses the forced convection heat transfer coefficient as a function of fluid temperature, pressure and velocity. 4. Theoretical studies of charge transfer and proton transfer complex formation between 3,5-dinitrobenzic acid and 1,2-dimethylimidazole Science.gov (United States) 2018-05-01 Natural atomic charge analysis and molecular electrostatic potential (MEP) surface analysis of hydrogen bonded charge transfer (HBCT) and proton transfer (PT) complex of 3,5-dinitrobenzoic acid (DNBA) and 1,2-dimethylimidazole (DMI) have been investigated by theoretical modelling using widely employed DFT/B3LYP/6-311G(d,p) level of theory. Along with this analysis, Hirshfeld surface study of the intermolecular interactions and associated 2D finger plot for reported PT complex between DNBA and DMI have been explored. 5. Charge transfer in carbon nanotube actuators investigated using in situ Raman spectroscopy International Nuclear Information System (INIS) Gupta, S.; Hughes, M.; Windle, A.H.; Robertson, J. 2004-01-01 Charge transfer dynamics on the surface of single-wall carbon nanotube sheets is investigated using in situ Raman spectroscopy in order to understand the actuation mechanism of an electrochemical actuator and to determine associated parameters. We built an actuator from single-wall carbon nanotube mat and studied its actuation in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide and sulfate solutions in order to clarify the role of counterion as mobile ions in the film. The variation of bonding with applied potential was monitored using in situ Raman spectroscopy. This is because Raman can detect changes in C-C bond length: the radial breathing mode at ∼190 cm-1 varies inversely with the nanotube diameter, and the G band at ∼1590 cm-1 varies with the axial bond length. In addition, the intensities of both the modes vary with the emptying/depleting or filling of the bonding and antibonding states due to electrochemical charge injection. We discussed the variation of peak height and wave numbers of these modes providing valuable information concerning electrochemical charge injection on the carbon nanotube mat surface. We found in-plane microscopic compressive strain (∼-0.25%) and the equivalent charge transfer per carbon atom (f c ∼-0.005) as an upper bound for the actuators studied hereby. It is demonstrated that though the present analysis does comply with the proposition for the actuation principle made earlier, the quantitative estimates are significantly lower if compared with those of reported values. Furthermore, the extent of variation, i.e., coupled electro-chemo-mechanical response of single-wall carbon nanotubes (SWNT) mat depended upon the type of counterion used (Group I versus Group II). The cyclic voltammetry and ac electrochemical impedance spectroscopy results were described briefly, which help to demonstrate well-developed capacitive behavior of SWNT mat and to estimate the specific capacitances as well. Summarizing, the 6. Design of a software for calculating isoelectric point of a polypeptide according to their net charge using the graphical programming language LabVIEW. Science.gov (United States) Tovar, Glomen 2018-01-01 A software to calculate the net charge and to predict the isoelectric point (pI) of a polypeptide is developed in this work using the graphical programming language LabVIEW. Through this instrument the net charges of the ionizable residues of the polypeptide chains of the proteins are calculated at different pH values, tabulated, pI is predicted and an Excel (-xls) type file is generated. In this work, the experimental values of the pIs (pI) of different proteins are compared with the values of the pIs (pI) calculated graphically, achieving a correlation coefficient (R) of 0.934746 which represents a good reliability for a p program can constitute an instrument applicable in the laboratory, facilitating the calculation to graduate students and junior researchers. © 2017 by The International Union of Biochemistry and Molecular Biology, 46(1):39-46, 2018. © 2017 The International Union of Biochemistry and Molecular Biology. 7. Scientific Computation Application Partnerships in Materials and Chemical Sciences, Charge Transfer and Charge Transport in Photoactivated Systems, Developing Electron-Correlated Methods for Excited State Structure and Dynamics in the NWChem Software Suite Energy Technology Data Exchange (ETDEWEB) Cramer, Christopher J. [Univ. of Minnesota, Minneapolis, MN (United States) 2017-11-12 Charge transfer and charge transport in photoactivated systems are fundamental processes that underlie solar energy capture, solar energy conversion, and photoactivated catalysis, both organometallic and enzymatic. We developed methods, algorithms, and software tools needed for reliable treatment of the underlying physics for charge transfer and charge transport, an undertaking with broad applicability to the goals of the fundamental-interaction component of the Department of Energy Office of Basic Energy Sciences and the exascale initiative of the Office of Advanced Scientific Computing Research. 8. Low-Energy Charge Transfer in Multiply-Charged Ion-Atom Collisions Studied with the Combined SCVB-MOCC Approach Directory of Open Access Journals (Sweden) B. Zygelman 2002-03-01 Full Text Available A survey of theoretical studies of charge transfer involving collisions of multiply-charged ions with atomic neutrals (H and He is presented. The calculations utilized the quantum-mechanical molecular-orbital close-coupling (MOCC approach where the requisite potential curves and coupling matrix elements have been obtained with the spin-coupled valence bond (SCVB method. Comparison is made among various collision partners, for equicharged systems, where it is illustrated that even for total charge transfer cross sections, scaling-laws do not exist for low-energy collisions (i.e. < 1 keV/amu. While various empirical scaling-laws are well known in the intermediateand high-energy regimes, the multi-electron configurations of the projectile ions results in a rich and varied low-energy dependence, requiring an explicit calculation for each collision-partner pair. Future charge transfer problems to be addressed with the combined SCVB-MOCC approach are briefly discussed. 9. Effect of the Net Charge Distribution on the Aqueous Solution Properties of Polyampholytes Effet de la répartition de la charge nette sur les propriétés des solutions aqueuses de polyampholytes Directory of Open Access Journals (Sweden) Candau F. 2006-12-01 Full Text Available The zwitterion nature of ampholytic polymers provides features that are useful in environmental and industrial applications, e. g. ion-exchange membrane, as flocculants in sewage treatment and in oil recovery processes. In the latter case, the increase in viscosity which is observed in the presence of brine (anti -polyelectrolyte behavior make them ideal candidates for high salinity media. The aqueous solution properties of a series of ampholytic terpolymers based on sodium-2-acrylamido-2- rilethylpropanesulfonate (NaAMPS, Methacryloyloxyethyltrimethylammonium chloride (MADQUAT and acrylamide (AM, prepared in inverse micro emulsions have been investigated by viscometry and light scattering experiments. The distribution of the net charge among the chains was varied by adjusting the initial monomer composition and the degree of conversion. The effect of this distribution on the solubility of the samples and on the chain conformation was studied. It was found that samples with a narrow distribution of net charges were soluble in water even if the average net charge is small. Addition of salt produces a transition from an extended conformation to a more compact one in qualitative agreement with theoretical predictions. A practically alternated NaAMPS- MADQUAT copolymer prepared in homogeneous solution and with a small average net charge shows a behaviour quite similar to that of the terpolymers. La nature zwitterioniquedes polymères ampholytes présente des caractéristiques qui sont utiles dans les applications environnementales et industrielles, comme les membranes d'échange ionique, les floculants dans le traitement des eaux usées et dans les procédés de récupération de pétrole. Dans ce dernier cas, l'augmentation de viscosité qui est observée en présence de saumure (comportement antipolyélectrolyte en fait des candidats idéaux pour des milieux de salinité élevée. Les propriétés de la solution aqueuse d'une série de terpolym 10. Quantitative description of the relation between protein net charge and protein adsorption to air-water interfaces NARCIS (Netherlands) Wierenga, P.A.; Meinders, M.B.J.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J.de 2005-01-01 In this study a set of chemically engineered variants of ovalbumin was produced to study the effects of electrostatic charge on the adsorption kinetics and resulting surface pressure at the air-water interface. The modification itself was based on the coupling of succinic anhydride to lysine 11. Sodium dodecyl benzene sulphonate mediated tautomerism of Eriochrome Black-T: Effect of charge transfer interaction Science.gov (United States) Ghosh, Sumit 2010-11-01 Interaction between anionic surfactant, sodium dodecyl benzene sulphonate, (SDBS) and an anionic dye Eriochrome Black-T, (EBT) has been investigated by visible spectroscopy, conductometry, dynamic light scattering and zeta potential measurements. Spectral changes of EBT observed on addition of SDBS indicate formation of quinone-hydrazone tautomer at pH 7.0, whereas in absence of SDBS this change appears at pH ˜ 9.45. However, at pH 7.0 this change in tautomerism is not observed in presence of sodium dodecyl sulphate (SDS). Experimental results indicate presence of charge transfer interaction between less stable quinone-hydrazone tautomer of EBT and SDBS molecules, which is confirmed using Benesi-Hildebrand and Scott equations. 12. Charge transfer in carbon composites based on fullerenes and exfoliated graphite Science.gov (United States) Berezkin, V. I. 2017-07-01 Kinetic processes have been studied in composites based on fullerenes and exfoliated graphite at the initial proportions of components from 1: 16 to 16: 1 in mass. The samples are produced by heat treatment of initial dispersed mixtures in vacuum in the diffusion-adsorption process, their further cold pressing, and annealing. It is shown that the annealing almost does not influence the conduction mechanisms and only induces additional structural defects acting as electron traps. As a whole, the results obtained at the noted proportions of components make it possible to consider the material as a compensated metallic system with a structural disorder in which the charge transfer at temperatures from 4.2 K to room temperature is controlled by quantum interference phenomena. At low temperatures, the effect of a weak localization is observed, and the electron-electron interactions take place at medium and high temperatures. 13. Charge transfer in graphene oxide-dye system for photonic applications International Nuclear Information System (INIS) Bongu, Sudhakara Reddy; Bisht, Prem B.; Thu, Tran V.; Sandhu, Adarsh 2014-01-01 The fluorescence of a standard dye Rhodamine 6G (R6G) in solution decreases on addition of reduced graphene oxide (rGO). The absorption spectra and lifetime measurements confirm that no excited-state but a ground-state complex formation is responsible for this effect. For silver decorated rGO (Ag-rGO), the quenching efficiency and ground state complex formation process is small. Z-scan measurements have been done to study the optical nonlinearity at 532 nm under ps time scale. Remarkable reduction in the saturable absorption (SA) effect of R6G indicates no nonlinear contribution from the ground state complex. The results have been explained with varying charge transfer rates and non-fluorescence nature of the complex 14. Charge transfer in rectifying oxide heterostructures and oxide access elements in ReRAM Energy Technology Data Exchange (ETDEWEB) Stefanovich, G. B.; Pergament, A. L.; Boriskov, P. P.; Kuroptev, V. A., E-mail: v.a.kuroptev@gmail.com; Stefanovich, T. G. [Petrozavodsk State University (Russian Federation) 2016-05-15 The main aspects of the synthesis and experimental research of oxide diode heterostructures are discussed with respect to their use as selector diodes, i.e., access elements in oxide resistive memory. It is shown that charge transfer in these materials differs significantly from the conduction mechanism in p–n junctions based on conventional semiconductors (Si, Ge, A{sup III}–B{sup V}), and the model should take into account the electronic properties of oxides, primarily the low carrier drift mobility. It is found that an increase in the forward current requires an oxide with a small band gap (<1.3 eV) in the heterostructure composition. Heterostructures with Zn, In–Zn (IZO), Ti, Ni, and Cu oxides are studied; it is found that the CuO–IZO heterojunction has the highest forward current density (10{sup 4} A/cm{sup 2}). 15. Charge transfer of He2+ with H in a strong magnetic field International Nuclear Information System (INIS) Liu Chun-Lei; Zou Shi-Yang; He Bin; Wang Jian-Guo 2015-01-01 By solving a time-dependent Schrödinger equation (TDSE), we studied the electron capture process in the He 2+ +H collision system under a strong magnetic field in a wide projectile energy range. The strong enhancement of the total charge transfer cross section is observed for the projectile energy below 2.0 keV/u. With the projectile energy increasing, the cross sections will reduce a little and then increase again, compared with those in the field-free case. The cross sections to the states with different magnetic quantum numbers are presented and analyzed where the influence due to Zeeman splitting is obviously found, especially in the low projectile energy region. The comparison with other models is made and the tendency of the cross section varying with the projectile energy is found closer to that from other close coupling models. (paper) 16. Low-energy charge transfer for collisions of Si3+ with atomic hydrogen Science.gov (United States) Bruhns, H.; Kreckel, H.; Savin, D. W.; Seely, D. G.; Havener, C. C. 2008-06-01 Cross sections of charge transfer for Si3+ ions with atomic hydrogen at collision energies of ≈40-2500eV/u were carried out using a merged-beam technique at the Multicharged Ion Research Facility at Oak Ridge National Laboratory. The data span an energy range in which both molecular orbital close coupling (MOCC) and classical trajectory Monte Carlo (CTMC) calculations are available. The influence of quantum mechanical effects of the ionic core as predicted by MOCC is clearly seen in our results. However, discrepancies between our experiment and MOCC results toward higher collision energies are observed. At energies above 1000 eV/u good agreement is found with CTMC results. 17. Ab initio study of charge transfer in B2+ low-energy collisions with atomic hydrogen Science.gov (United States) Turner, A. R.; Cooper, D. L.; Wang, J. G.; Stancil, P. C. 2003-07-01 Charge transfer processes due to collisions of ground state B2+(2s 2S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with the existing experiments shows our results to be in good agreement. When EMOCC cross sections with and without rotational coupling are small (400 eV/u, inclusion of rotational coupling increases the total cross section by 50% 80%, improving the agreement between the current calculations and experiments. For state-selective cross sections, rotational coupling induces mixing between different symmetries; however, its effect, especially at low collision energies, is not as important as had been suggested in previous work. 18. Vibrationally-resolved Charge Transfer of O^3+ Ions with Molecular Hydrogen Science.gov (United States) Wang, J. G.; Stancil, P. C.; Turner, A. R.; Cooper, D. L. 2003-05-01 Charge transfer processes due to collisions of ground state O^3+ ions with H2 are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained with the spin-coupled valence-bond approach. Vibrationally-resolved cross sections for energies between 0.1 eV/u and 2 keV/u using the infinite order sudden approximation (IOSA), vibrational sudden approximation (VSA), and electronic approximation (EA), but including Frank-Condon factors (the centroid approximation) will be presented. Comparison with existing experimental data for total cross sections shows best agreement with IOSA and discrepancies for VSA and EA. Triplet-singlet cross section ratios obtained with IOSA are found generally to be in harmony with experiment. JGW and PCS acknowledge support from NASA grant 11453. 19. Low Energy Charge Transfer for Collisions of Si3+ with Atomic Hydrogen Energy Technology Data Exchange (ETDEWEB) Bruhns, H. [Columbia University; Kreckel, H. [Columbia University; Savin, D. W. [Columbia University; Seely, D. G. [Albion College; Havener, Charles C [ORNL 2008-01-01 Cross sections of charge transfer for Si{sup 3+} ions with atomic hydrogen at collision energies of {approx} 40-2500 eV/u were carried out using a merged-beam technique at the Multicharged Ion Research Facility at Oak Ridge National Laboratory. The data span an energy range in which both molecular orbital close coupling (MOCC) and classical trajectory Monte Carlo (CTMC) calculations are available. The influence of quantum mechanical effects of the ionic core as predicted by MOCC is clearly seen in our results. However, discrepancies between our experiment and MOCC results toward higher collision energies are observed. At energies above 1000 eV/u good agreement is found with CTMC results. 20. Ab initio study of charge transfer in B2+ low-energy collisions with atomic hydrogen International Nuclear Information System (INIS) Turner, A.R.; Cooper, D.L.; Wang, J.G.; Stancil, P.C. 2003-01-01 Charge transfer processes due to collisions of ground state B 2+ (2s 2 S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) method. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial and rotational coupling matrix elements obtained with the spin-coupled valence-bond approach. Total and state-selective cross sections and rate coefficients are presented. Comparison with the existing experiments shows our results to be in good agreement. When E 400 eV/u, inclusion of rotational coupling increases the total cross section by 50%-80%, improving the agreement between the current calculations and experiments. For state-selective cross sections, rotational coupling induces mixing between different symmetries; however, its effect, especially at low collision energies, is not as important as had been suggested in previous work 1. Dielectric Losses and Charge Transfer in Antimony-Doped TlGaS2 Single Crystal Science.gov (United States) Asadov, S. M.; Mustafaeva, S. N. 2018-03-01 Effect of semimetallic antimony (0.5 mol % Sb) on the dielectric properties and ac-conductivity of TlGaS2-based single crystals grown by the Bridgman-Stockbarger method has been studied. The experimental results on the frequency dispersion of dielectric coefficients and the conductivity of TlGa0.995Sb0.005S2 single crystals allowed the revealing of the dielectric loss nature, the charge transfer mechanism, and the estimation of the parameters of the states localized in the energy gap. The antimony-doping of the TlGaS2 single crystal leads to an increase in the density of states near the Fermi level and a decrease in the average time and average distance of hopes. 2. Manipulation of charge transfer and transport in plasmonic-ferroelectric hybrids for photoelectrochemical applications Science.gov (United States) Wang, Zhijie; Cao, Dawei; Wen, Liaoyong; Xu, Rui; Obergfell, Manuel; Mi, Yan; Zhan, Zhibing; Nasori, Nasori; Demsar, Jure; Lei, Yong 2016-01-01 Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting. PMID:26753764 3. Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene Directory of Open Access Journals (Sweden) Jun Hu 2013-12-01 Full Text Available We describe herein the two-component charge-transfer (CT interaction induced organogel formation with 18β-glycyrrhetinic acid appended pyrene (GA-pyrene, 3 as the donor, and 2,4,7-trinitrofluorenone (TNF, 4 as the acceptor. The use of TNF (4 as a versatile electron acceptor in the formation of CT gels is demonstrated through the formation of gels in a variety of solvents. Thermal stability, stoichiometry, scanning electron microscopy (SEM, optical micrographs, and circular dichroism (CD are performed on these CT gels to investigate their thermal and assembly properties. UV–vis, fluorescence, mass spectrometric as well as variable-temperature 1H NMR experiments on these gels suggest that the CT interaction is one of the major driving forces for the formation of these organogels. 4. ZnO nanowires: Synthesis and charge transfer mechanism in the detection of ammonia vapour Science.gov (United States) Nancy Anna Anasthasiya, A.; Ramya, S.; Rai, P. K.; Jeyaprakash, B. G. 2018-01-01 ZnO nanowires with hexagonal wurtzite structure were grown on the glass substrate using Successive Ionic Layer Adsorption and Reaction (SILAR) method. Both experimental and theoretical studies demonstrated that NH3 chemisorbed and transferred the charge to the surface of the nanowire via its nitrogen site to the zinc site of ZnO nanowires, leading to the detection of NH3 vapour. The adsorbed ammonia dissociated into NH2 and H due to steric repulsion, and then into N2 and H2 gas. The formation of the N2 gas during the desorption process confirmed by observing peak at 14 and 28 m/z in the GC-MS spectrum. 5. Correlation between the Open-Circuit Voltage and Charge Transfer State Energy in Organic Photovoltaic Cells. Science.gov (United States) Zou, Yunlong; Holmes, Russell J 2015-08-26 In order to further improve the performance of organic photovoltaic cells (OPVs), it is essential to better understand the factors that limit the open-circuit voltage (VOC). Previous work has sought to correlate the value of VOC in donor-acceptor (D-A) OPVs to the interface energy level offset (EDA). In this work, measurements of electroluminescence are used to extract the charge transfer (CT) state energy for multiple small molecule D-A pairings. The CT state as measured from electroluminescence is found to show better correlation to the maximum VOC than EDA. The difference between EDA and the CT state energy is attributed to the Coulombic binding energy of the CT state. This correlation is demonstrated explicitly by inserting an insulating spacer layer between the donor and acceptor materials, reducing the binding energy of the CT state and increasing the measured VOC. These results demonstrate a direct correlation between maximum VOC and CT state energy. 6. Charge transfer complex states in diketopyrrolopyrrole polymers and fullerene blends: Implications for organic solar cell efficiency Science.gov (United States) Moghe, D.; Yu, P.; Kanimozhi, C.; Patil, S.; Guha, S. 2011-12-01 The spectral photocurrent characteristics of two donor-acceptor diketopyrrolopyrrole (DPP)-based copolymers (PDPP-BBT and TDPP-BBT) blended with a fullerene derivative [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were studied using Fourier-transform photocurrent spectroscopy (FTPS) and monochromatic photocurrent (PC) method. PDPP-BBT:PCBM shows the onset of the lowest charge transfer complex (CTC) state at 1.42 eV, whereas TDPP-BBT:PCBM shows no evidence of the formation of a midgap CTC state. The FTPS and PC spectra of P3HT:PCBM are also compared. The larger singlet state energy difference of TDPP-BBT and PCBM compared to PDPP-BBT/P3HT and PCBM obliterates the formation of a midgap CTC state resulting in an enhanced photovoltaic efficiency over PDPP-BBT:PCBM. 7. Positron annihilation in liquids and in solutions containing electron acceptors and charge-transfer complexes International Nuclear Information System (INIS) Jansen, P. 1976-05-01 Positron lifetime measurements and angular correlation measurements were performed in several organic liquids. The results strongly indicate that positronium is contained in a 'bubble' in the liquids. The radius of the bubble can be estimated by using broadness of the narrow component in the angular correlation distribution, and by using the surface tension of the liquids. Both methods give bubble radii from 4-7 A in the solvents investigated. The bubble influences the reaction mechanism between Ps and weak electron acceptors in such a way that the presence of the bubble decreases the reactivity of Ps. Positron lifetime measurements were also performed on a series of mixtures of organic liquids and on electron acceptors and charge-transfer complexes in solution. The results were is agreement with the spur model of Ps formation. (Auth.) 8. The effect of interfacial charge transfer on ferromagnetism in perovskite oxide superlattices Energy Technology Data Exchange (ETDEWEB) Yang, F. [Univ. of California, Davis, CA (United States). Department of Chemical Engineering and Materials Science; Gu, M. [Univ. of California, Davis, CA (United States). Department of Chemical Engineering and Materials Science; Arenholz, E. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Browning, N. D. [Univ. of California, Davis, CA (United States). Department of Molecular and Cellular Biology; Takamura, Y. [Univ. of California, Davis, CA (United States). Department of Chemical Engineering and Materials Science 2012-01-05 We investigate the structural, magnetic, and electrical properties of superlattices composed of the ferromagnetic/metal La0.7Sr0.3MnO3 and non-magnetic/metal La0.5Sr0.5TiO3 grown on (001)-oriented SrTiO3 substrates. Using a combination of bulk magnetometry, soft x-ray magnetic spectroscopy, and scanning transmission electron microscopy, we demonstrate that robust ferromagnetic properties can be maintained in this superlattice system where charge transfer at the interfaces is minimized. Thus, ferromagnetism can be controlled effectively through the chemical identity and the thickness of the individual superlattice layers. 9. Engineering high charge transfer n-doping of graphene electrodes and its application to organic electronics. Science.gov (United States) Sanders, Simon; Cabrero-Vilatela, Andrea; Kidambi, Piran R; Alexander-Webber, Jack A; Weijtens, Christ; Braeuninger-Weimer, Philipp; Aria, Adrianus I; Qasim, Malik M; Wilkinson, Timothy D; Robertson, John; Hofmann, Stephan; Meyer, Jens 2015-08-14 Using thermally evaporated cesium carbonate (Cs2CO3) in an organic matrix, we present a novel strategy for efficient n-doping of monolayer graphene and a ∼90% reduction in its sheet resistance to ∼250 Ohm sq(-1). Photoemission spectroscopy confirms the presence of a large interface dipole of ∼0.9 eV between graphene and the Cs2CO3/organic matrix. This leads to a strong charge transfer based doping of graphene with a Fermi level shift of ∼1.0 eV. Using this approach we demonstrate efficient, standard industrial manufacturing process compatible graphene-based inverted organic light emitting diodes on glass and flexible substrates with efficiencies comparable to those of state-of-the-art ITO based devices. 10. Intramolecular Charge-Transfer Interaction of Donor-Acceptor-Donor Arrays Based on Anthracene Bisimide. Science.gov (United States) Iwanaga, Tetsuo; Ogawa, Marina; Yamauchi, Tomokazu; Toyota, Shinji 2016-05-20 We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions. Introducing ethynylene linkers resulted in a considerable red shift of the absorption bands. In fluorescence spectra, the ethynylene derivatives showed intense emission bands at 600-650 nm. Their photophysical and electrochemical properties were compared with those of the corresponding mono TPA derivatives on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between the donor and acceptor units. 11. Supramolecular fullerene/porphyrin charge transfer interaction studied by absorption spectrophotometric method Science.gov (United States) Mukherjee, Partha; Bhattacharya (Banerjee), Shrabanti; Nayak, Sandip K.; Chattopadhyay, Subrata; Bhattacharya, Sumanta 2009-06-01 A detailed UV-Vis spectrometric and thermodynamic studies were done to look insight into the nature of molecular interactions of the electron donor-acceptor complexes of C60 and C70 with 5,10,15,20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (1) in chloroform and toluene. Charge transfer (CT) absorption bands were located in the visible region and vertical ionization potential of 1 was determined utilizing CT transition energy. Low values of oscillator and transition dipole strengths suggested that the complexes were almost of neutral character in ground states. The high binding constant value for the C70-1 complex indicated high selectivity of 1 molecule towards C70. Experimental as well as theoretically determined of enthalpies of formation value substantiated the trend in K values for fullerene-1 complexes. 12. Charge transfer from and to manganese phthalocyanine: bulk materials and interfaces Directory of Open Access Journals (Sweden) Florian Rückerl 2017-08-01 Full Text Available Manganese phthalocyanine (MnPc is a member of the family of transition-metal phthalocyanines, which combines interesting electronic behavior in the fields of organic and molecular electronics with local magnetic moments. MnPc is characterized by hybrid states between the Mn 3d orbitals and the π orbitals of the ligand very close to the Fermi level. This causes particular physical properties, different from those of the other phthalocyanines, such as a rather small ionization potential, a small band gap and a large electron affinity. These can be exploited to prepare particular compounds and interfaces with appropriate partners, which are characterized by a charge transfer from or to MnPc. We summarize recent spectroscopic and theoretical results that have been achieved in this regard. 13. Laser-induced charge transfer in the CH/sup 6 +/ quasimolecule Energy Technology Data Exchange (ETDEWEB) Errea, L.F.; Mendez, L.; Riera, A. 1985-05-15 The charge transfer cross section is calculated for C/sup 6 +/+CH(1s) collisions, through photon assisted 5gsigma--6hsigma, 5gsigma--4fsigma, 5gsigma--4f..pi.., and 5gsigma--4dsigma transitions. The theory developed by Copeland and Tang, and ourselves, is employed, and the validity of the approximations used is tested. The four processes considered have widely different characteristics with regards to the laser wavelength needed, the collision dynamics and the applicability of back-of-the-envelope estimates based on the Landau--Zener approximation. We point out the relevance of those processes to the impurity diagnostics of magnetically confined fusion plasmas and to the development of short wavelength lasers. 14. The role of molecular mobility in the transfer of charge generated by ionizing radiation in polymers International Nuclear Information System (INIS) Khatinov, S.A.; Edrisov, K.M.; Turdybekov, K.M.; Milinchuk, V.K. 1995-01-01 The dependence of radiation-induced electrical conductivity on the irradiation time and temperature was studied for a number of polymers. The character of variation of radiation-induced conductivity with time and temperature correlates with the physical state of a polymer. Defreezing of the segmental mobility in the region of α-relaxation transition leads to a sharp change in radiation-induced conductivity, and the appearance of peaks in the kinetic curves and break points on the Arrhenius plots in conductivity versus temperature coordinates. Molecular mobility plays a determining role in the transfer of charge carriers generated by radiation. This conclusion agrees with the data on the carrier mobility obtained by the time-of-flight methods. 24 refs., 8 figs 15. Annealing bounds to prevent further Charge Transfer Inefficiency increase of the Chandra X-ray CCDs Energy Technology Data Exchange (ETDEWEB) Monmeyran, Corentin, E-mail: comonmey@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Patel, Neil S., E-mail: neilp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Bautz, Mark W., E-mail: mwb@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Grant, Catherine E., E-mail: cgrant@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Prigozhin, Gregory Y., E-mail: gyp@space.mit.edu [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Agarwal, Anuradha, E-mail: anu@mit.edu [Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Kimerling, Lionel C., E-mail: lckim@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States) 2016-12-15 After the front-illuminated CCDs on board the X-ray telescope Chandra were damaged by radiation after launch, it was decided to anneal them in an effort to remove the defects introduced by the irradiation. The annealing led to an unexpected increase of the Charge Transfer Inefficiency (CTI). The performance degradation is attributed to point defect interactions in the devices. Specifically, the annealing at 30 °C activated the diffusion of the main interstitial defect in the device, the carbon interstitial, which led to its association with a substitutional impurity, ultimately resulting in a stable and electrically active defect state. Because the formation reaction of this carbon interstitial and substitutional impurity associate is diffusion limited, we recommend a higher upper bound for the annealing temperature and duration of any future CCD anneals, that of −50 °C for one day or −60 °C for a week, to prevent further CTI increase. 16. Nanoscale charge transfer in redox proteins and DNA: Towards biomolecular electronics International Nuclear Information System (INIS) Artés, Juan Manuel; López-Martínez, Montserrat; Díez-Pérez, Ismael; Sanz, Fausto; Gorostiza, Pau 2014-01-01 Understanding how charges move through and between biomolecules is a fundamental question that constitutes the basis for many biological processes. On the other hand, it has potential applications in the design of sensors based on biomolecules and single molecule devices. In this review we introduce the study of the electron transfer (ET) process in biomolecules, providing an overview of the fundamental theory behind it and the different experimental approaches. The ET in proteins is introduced by reviewing a complete electronic characterization of a redox protein (azurin) using electrochemical scanning tunnelling microscopy (ECSTM). The ET process in DNA is overviewed and results from different experimental approaches are discussed. Finally, future directions in the study of the ET process in biomolecules are introduced as well as examples of possible technological applications 17. Charge transfer excitations from exact and approximate ensemble Kohn-Sham theory Science.gov (United States) Gould, Tim; Kronik, Leeor; Pittalis, Stefano 2018-05-01 By studying the lowest excitations of an exactly solvable one-dimensional soft-Coulomb molecular model, we show that components of Kohn-Sham ensembles can be used to describe charge transfer processes. Furthermore, we compute the approximate excitation energies obtained by using the exact ensemble densities in the recently formulated ensemble Hartree-exchange theory [T. Gould and S. Pittalis, Phys. Rev. Lett. 119, 243001 (2017)]. Remarkably, our results show that triplet excitations are accurately reproduced across a dissociation curve in all cases tested, even in systems where ground state energies are poor due to strong static correlations. Singlet excitations exhibit larger deviations from exact results but are still reproduced semi-quantitatively. 18. Robust singlet fission in pentacene thin films with tuned charge transfer interactions. Science.gov (United States) Broch, K; Dieterle, J; Branchi, F; Hestand, N J; Olivier, Y; Tamura, H; Cruz, C; Nichols, V M; Hinderhofer, A; Beljonne, D; Spano, F C; Cerullo, G; Bardeen, C J; Schreiber, F 2018-03-05 Singlet fission, the spin-allowed photophysical process converting an excited singlet state into two triplet states, has attracted significant attention for device applications. Research so far has focused mainly on the understanding of singlet fission in pure materials, yet blends offer the promise of a controlled tuning of intermolecular interactions, impacting singlet fission efficiencies. Here we report a study of singlet fission in mixtures of pentacene with weakly interacting spacer molecules. Comparison of experimentally determined stationary optical properties and theoretical calculations indicates a reduction of charge-transfer interactions between pentacene molecules with increasing spacer molecule fraction. Theory predicts that the reduced interactions slow down singlet fission in these blends, but surprisingly we find that singlet fission occurs on a timescale comparable to that in pure crystalline pentacene. We explain the observed robustness of singlet fission in such mixed films by a mechanism of exciton diffusion to hot spots with closer intermolecular spacings. 19. Charge-Transfer Processes in Warm Dense Matter: Selective Spectral Filtering for Laser-Accelerated Ion Beams Science.gov (United States) Braenzel, J.; Barriga-Carrasco, M. D.; Morales, R.; Schnürer, M. 2018-05-01 We investigate, both experimentally and theoretically, how the spectral distribution of laser accelerated carbon ions can be filtered by charge exchange processes in a double foil target setup. Carbon ions at multiple charge states with an initially wide kinetic energy spectrum, from 0.1 to 18 MeV, were detected with a remarkably narrow spectral bandwidth after they had passed through an ultrathin and partially ionized foil. With our theoretical calculations, we demonstrate that this process is a consequence of the evolution of the carbon ion charge states in the second foil. We calculated the resulting spectral distribution separately for each ion species by solving the rate equations for electron loss and capture processes within a collisional radiative model. We determine how the efficiency of charge transfer processes can be manipulated by controlling the ionization degree of the transfer matter. 20. Heat transfer enhancement of phase change materials by fins under simultaneous charging and discharging International Nuclear Information System (INIS) Joybari, Mahmood Mastani; Haghighat, Fariborz; Seddegh, Saeid; Al-Abidi, Abduljalil A. 2017-01-01 Highlights: • CFD simulation of a finned triplex tube heat exchanger with PCM under simultaneous charging and discharging. • Developed fin configurations for SCD, compatible with natural convection. • More fins enhanced the heat transfer as long as natural convection was not suppressed. • Longer fins enhanced the heat transfer as long as natural convection was not suppressed. • The effect of fin thickness was negligible, similar to non-SCD conditions. - Abstract: Due to the inherent intermittency of renewable energy sources such as solar, latent heat thermal energy storage in phase change materials (PCMs) has received considerable attention. Among several techniques to enhance PCMs’ thermal conductivity, the majority of studies have focused on fin integration due to its simplicity, ease of manufacturing, and low cost. In this study, utilization of extended surfaces (by longitudinal fins) was investigated by development of a numerical model to study the performance of a triplex tube heat exchanger (TTHX) equipped with a PCM under simultaneous charging and discharging (SCD). Governing equations were developed and numerically solved using ANSYS Fluent v16.2. Three conventional fin geometries and six developed fin configurations were compared based on the temperature, liquid fraction, and natural convection behavior under both SCD and non-SCD conditions. The intensity of natural convection was investigated for different fins for the inside heating/outside cooling scenario based on the solid–liquid interface evolution over time. The results indicated that since the buoyancy forces induce upward melted PCM motion, the inner hot tube requires fins on its lower half, while the outer cold one should be extended from its upper half. It was concluded that the case with 3 hot tube fins and 1 cold tube fin is most compatible with natural convection and provides the best performance under SCD conditions. 1. Spectroscopic study of the charge-transfer complexes TiCl4/styrene and TiCl4/polystyrene Science.gov (United States) Gonçalves, Norberto S.; Noda, Lúcia. K. 2017-10-01 In this work, solutions of TiCl4/styrene and TiCl4/polystyrene charge-transfer complexes in CHCl3 or CDCl3 were investigated by UV-vis, resonance Raman and 1H NMR spectroscopies in order to study their molecular and electronic structures. Both show a yellow colour due to absorption in the 400 nm region, related to a charge-transfer transition. In Raman spectra, as the excitation approaches the resonance region, the primary enhancement of aromatic ring modes was mainly observed, rather than intensification of the vinylic double-bond stretch. Under the experimental conditions it was observed that formation of polystyrene takes place, as showed by 1H NMR spectra, and the most significant interaction occurs at the aromatic ring, as supported by the results from interaction of TiCl4 with polystyrene, as indicated by the charge-transfer band and resonant intensification of the aromatic ring modes. 2. Direct evidence for radiative charge transfer after inner-shell excitation and ionization of large clusters Science.gov (United States) Hans, Andreas; Stumpf, Vasili; Holzapfel, Xaver; Wiegandt, Florian; Schmidt, Philipp; Ozga, Christian; Reiß, Philipp; Ben Ltaief, Ltaief; Küstner-Wetekam, Catmarna; Jahnke, Till; Ehresmann, Arno; Demekhin, Philipp V.; Gokhberg, Kirill; Knie, André 2018-01-01 We directly observe radiative charge transfer (RCT) in Ne clusters by dispersed vacuum-ultraviolet photon detection. The doubly ionized Ne2+-{{{N}}{{e}}}n-1 initial states of RCT are populated after resonant 1s-3p photoexcitation or 1s photoionization of Ne n clusters with ≈ 2800. These states relax further producing Ne+-Ne+-{{{N}}{{e}}}n-2 final states, and the RCT photon is emitted. Ab initio calculations assign the observed RCT signal to the{}{{{N}}{{e}}}2+(2{{{p}}}-2{[}1{{D}}]){--}{{{N}}{{e}}}n-1 initial state, while transitions from other possible initial states are proposed to be quenched by competing relaxation processes. The present results are in agreement with the commonly discussed scenario, where the doubly ionized atom in a noble gas cluster forms a dimer which dissipates its vibrational energy on a picosecond timescale. Our study complements the picture of the RCT process in weakly bound clusters, providing information which is inaccessible by charged particle detection techniques. 3. Charge transfer effects of ions at the liquid water/vapor interface Energy Technology Data Exchange (ETDEWEB) Soniat, Marielle; Rick, Steven W., E-mail: srick@uno.edu [Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148 (United States) 2014-05-14 Charge transfer (CT), the movement of small amounts of electron density between non-bonded pairs, has been suggested as a driving force for a variety of physical processes. Herein, we examine the effect of CT on ion adsorption to the water liquid-vapor interface. Using a CT force field for molecular dynamics, we construct a potential of mean force (PMF) for Na{sup +}, K{sup +}, Cl{sup −}, and I{sup −}. The PMFs were produced with respect to an average interface and an instantaneous interface. An analysis of the PMF relative to the instantaneous surface reveals that the area in which the anions experience a free energy minimum is quite narrow, and the cations feel a steeply repulsive free energy near the interface. CT is seen to have only minor effects on the overall free energy profiles. However, the long-ranged effects of ions are highlighted by the CT model. Due to CT, the water molecules at the surface become charged, even when the ion is over 15 Å away from the surface. 4. Photophysical study of a charge transfer oxazole dye in micelles: Role of surfactant headgroups Energy Technology Data Exchange (ETDEWEB) Maiti, Jyotirmay [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Sarkar, Yeasmin; Parui, Partha Pratim [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Chakraborty, Sandipan [Department of Microbiology, University of Calcutta, Kolkata 700019 (India); Biswas, Suman [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India); Das, Ranjan, E-mail: ranjan.das68@gmail.com [Department of Chemistry, West Bengal State University, Barasat, Kolkata 700126 (India) 2015-07-15 Photophysics of 5-(4′′-dimethylaminophenyl)-2-(4′-sulfophenyl)oxazole, sodium salt (DMO) which undergoes intramolecular charge transfer in the excited state was studied in micelles. In the cationic and the nonionic micelles, significantly higher fluorescence quantum yield is observed in comparison to the anionic micelles, due to much lower accessibility of DMO to the water molecules in the former micelles than the latter. Time-resolved fluorescence decays were characterized by a fast (τ{sub 1}) and a slow (τ{sub 2}) component of decay in all the micelles. The fast decay component (τ{sub 1}) increases significantly in going from the anionic micelles to the cationic micelles, because of the poorly hydrated headgroup region of the latter micelles compared to the former. Furthermore, much higher value of the slow component of decay (τ{sub 2}) is observed for the cationic and the neutral micelles than the anionic micelles. This is attributed to the increased penetration of water molecules into the micellar core of the anionic micelles compared to the cationic and the neutral micelles. - Highlights: • Photophysics of the fluorophore are remarkably different in the cationic and the anionic micelles. • Differential hydration of the surfactant headgroups gives rise to significantly different fluorescence quantum yield and lifetime in oppositely charged micelles. • Electrostatic interactions fine tune location of the fluorophore in the micelle–water interface of ionic micelles. 5. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity International Nuclear Information System (INIS) Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G. 2014-01-01 We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4–5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers. 6. A charge transfer complex nematic liquid crystalline gel with high electrical conductivity Science.gov (United States) Bhargavi, R.; Nair, Geetha G.; Krishna Prasad, S.; Majumdar, R.; Bag, Braja G. 2014-10-01 We describe the rheological, dielectric and elastic properties of a nematic liquid crystal gel created using an anthrylidene derivative of arjunolic acid, a chiral triterpenoid, obtained from the extracts of the wood of Terminalia arjuna. In this novel gel, having the electron-donor and acceptor components as minority constituents, the gelation and strengthening of charge-transfer complex (CTC) formation are seen to be occurring concomitantly. In addition to being mechanically strong with a large storage modulus, the gel with the maximized CTC exhibits Frank bend elastic constant values that approach nanonewton levels. The highlight of the study is the observation of 4-5 orders of magnitude increase in electrical conductivity for this gel, a value that is higher than even in the CT complexes of 2-d ordered columnar structures. A further important advantage of the present system over the columnar complex is that the high conductivity is seen for ac probing also, and owing to the nematic nature can be switched between its anisotropic limits. Some of these features are ascribed to a specific molecular packing architecture, which reduces the trapping of the charge carriers. 7. Frequency dependent magneto-transport in charge transfer Co(II) complex Energy Technology Data Exchange (ETDEWEB) Shaw, Bikash Kumar; Saha, Shyamal K., E-mail: cnssks@iacs.res.in 2014-09-01 A charge transfer chelated system containing ferromagnetic metal centers is the ideal system to investigate the magneto-transport and magneto-dielectric effects due to the presence of both electronic as well as magnetic properties and their coupling. Magneto-transport properties in materials are usually studied through dc charge transport under magnetic field. As frequency dependent conductivity is an essential tool to understand the nature of carrier wave, its spatial extension and their mutual interaction, in the present work, we have investigated frequency dependent magneto-transport along with magnetization behavior in [Co{sub 2}(II)-(5-(4-PhMe)-1,3,4-oxadiazole-H{sup +}-2-thiolate){sub 5}](OAc){sub 4} metal complex to elucidate the nature of above quantities and their response under magnetic field in the transport property. We have used the existing model for ac conduction incorporating the field dependence to explain the frequency dependent magneto-transport. It is seen that the frequency dependent magneto-transport could be well explained using the existing model for ac conduction. -Highlights: • Chelated Co(II) complex is synthesized for magneto-transport applications. • Frequency dependent magneto-transport and magnetization behavior are studied. • Nature of carrier wave, its spatial extension is investigated under magnetic field. • Existing model for ac conduction is used with magnetic field dependence. 8. The charge transfer induced by Cr doping in MgB2 International Nuclear Information System (INIS) Zhang Huarong; Zhao Jiyin; Shi Lei 2005-01-01 Mg 1-x Cr x B 2 polycrystal bulk samples with 0 x 5% have been synthesized by a solid-state reaction and studied by X-ray diffraction, SEM and Raman spectrum. It is found that the c-axis of the lattice decreases as the Cr content increases, while the a-axis remains unchanged. Moreover, crystal grain size increases apparently with Cr doping concentration increase. The normal-state resistivity increases and the superconducting transition temperature (T c ) decreases from 38.2 K (x = 0) to 35.1 K (x 0.03) with the increase of Cr content. It is suggested that the charge transfer between the Mg-layer and the B-layer causes the decrease of the charge carrier concentration and induces the changes of T c and normal-state resistivity. On the other hand, by the Raman scattering study, it is found that the linewidth of Raman spectrum increases with the increase of Cr content, which is resulted by the competition between the electron-phonon interaction and substitution-induced disorder. The Raman peak has no evident shift due to the countervailing between the effects of the electron-phonon coupling and the grain size 9. Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping. Science.gov (United States) Begum, Raihana; Parida, Manas R; Abdelhady, Ahmed L; Murali, Banavoth; Alyami, Noktan M; Ahmed, Ghada H; Hedhili, Mohamed Nejib; Bakr, Osman M; Mohammed, Omar F 2017-01-18 Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr 3 perovskite NCs with heterovalent Bi 3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors. 10. Engineering Interfacial Charge Transfer in CsPbBr3 Perovskite Nanocrystals by Heterovalent Doping KAUST Repository Begum, Raihana 2016-12-17 Since compelling device efficiencies of perovskite solar cells have been achieved, investigative efforts have turned to understand other key challenges in these systems, such as engineering interfacial energy-level alignment and charge transfer (CT). However, these types of studies on perovskite thin-film devices are impeded by the morphological and compositional heterogeneity of the films and their ill-defined surfaces. Here, we use well-defined ligand-protected perovskite nanocrystals (NCs) as model systems to elucidate the role of heterovalent doping on charge-carrier dynamics and energy level alignment at the interface of perovskite NCs with molecular acceptors. More specifically, we develop an in situ doping approach for colloidal CsPbBr3 perovskite NCs with heterovalent Bi3+ ions by hot injection to precisely tune their band structure and excited-state dynamics. This synthetic method allowed us to map the impact of doping on CT from the NCs to different molecular acceptors. Using time-resolved spectroscopy with broadband capability, we clearly demonstrate that CT at the interface of NCs can be tuned and promoted by metal ion doping. We found that doping increases the energy difference between states of the molecular acceptor and the donor moieties, subsequently facilitating the interfacial CT process. This work highlights the key variable components not only for promoting interfacial CT in perovskites, but also for establishing a higher degree of precision and control over the surface and the interface of perovskite molecular acceptors. 11. A how-to approach for a 3D simulation of charge transfer characteristics in a gas electron multiplier (GEM) CERN Document Server Sharma, A 1999-01-01 In this paper a detailed description of how to simulate charge transfer processes in a gaseous device is presented, taking the gas electron multiplier (GEM) as an example. A 3-dimensional simulation of the electric field and avalanche is performed. Results on charge transport are compared to experiment and agree within experimental errors; the avalanche mechanism and positive ion feedback are studied. The procedures used in the simulation are described in detail, and program scripts are appended. (15 refs). 12. Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2 '-bipyridine)(CN)4]2- DEFF Research Database (Denmark) Kjær, Kasper Skov; Kunnus, Kristjan; Harlang, Tobias C. B. 2018-01-01 The excited state dynamics of solvated [Fe(bpy)(CN)4]2-, where bpy = 2,2'-bipyridine, show significant sensitivity to the solvent Lewis acidity. Using a combination of optical absorption and X-ray emission transient spectroscopies, we have previously shown that the metal to ligand charge transfer...... the MLCT excited state relaxation dynamics of [Fe(bpy)(CN)4]2- in water, a strong Lewis acid solvent. The charge-transfer excited state is now found to decay in less than 100 femtoseconds, forming a quasi-stable metal centered excited state with a 13 picosecond lifetime. We find that this MC excited state...... developed for solar applications.... 13. Charge transfer processes in hybrid solar cells composed of amorphous silicon and organic materials Energy Technology Data Exchange (ETDEWEB) Schaefer, Sebastian; Neher, Dieter [Universitaet Potsdam, Inst. Physik u. Astronomie, Karl-Liebknecht-Strasse 24/25, 14467 Potsdam-Golm (Germany); Schulze, Tim; Korte, Lars [Helmholtz Zentrum Berlin, Inst. fuer Silizium Photovoltaik, Kekulestrasse 5, 12489 Berlin (Germany) 2011-07-01 The efficiency of hybrid solar cells composed of organic materials and amorphous hydrogenated silicon (a-Si:H) strongly depends upon the efficiency of charge transfer processes at the inorganic-organic interface. We investigated the performance of devices comprising an ITO/a-Si:H(n-type)/a-Si:H(intrinsic)/organic/metal multilayer structure and using two different organic components: zinc phthalocyanine (ZnPc) and poly(3-hexylthiophene) (P3HT). The results show higher power conversion- and quantum efficiencies for the P3HT based cells, compared to ZnPc. This can be explained by larger energy-level offset at the interface between the organic layer and a-Si:H, which facilitates hole transfer from occupied states in the valence band tail to the HOMO of the organic material and additionally promotes exciton splitting. The performance of the a-Si:H/P3HT cells can be further improved by treatment of the amorphous silicon surface with hydrofluoric acid (HF) and p-type doping of P3HT with F4TCNQ. The improved cells reached maximum power conversion efficiencies of 1%. 14. Direct evidence of charge separation in a metal-organic framework: efficient and selective photocatalytic oxidative coupling of amines via charge and energy transfer. Science.gov (United States) Xu, Caiyun; Liu, Hang; Li, Dandan; Su, Ji-Hu; Jiang, Hai-Long 2018-03-28 The selective aerobic oxidative coupling of amines under mild conditions is an important laboratory and commercial procedure yet a great challenge. In this work, a porphyrinic metal-organic framework, PCN-222, was employed to catalyze the reaction. Upon visible light irradiation, the semiconductor-like behavior of PCN-222 initiates charge separation, evidently generating oxygen-centered active sites in Zr-oxo clusters indicated by enhanced porphyrin π-cation radical signals. The photogenerated electrons and holes further activate oxygen and amines, respectively, to give the corresponding redox products, both of which have been detected for the first time. The porphyrin motifs generate singlet oxygen based on energy transfer to further promote the reaction. As a result, PCN-222 exhibits excellent photocatalytic activity, selectivity and recyclability, far superior to its organic counterpart, for the reaction under ambient conditions via combined energy and charge transfer. 15. DFT and TD-DFT computation of charge transfer complex between o-phenylenediamine and 3,5-dinitrosalicylic acid International Nuclear Information System (INIS) 2016-01-01 DFT and TD-DFT studies of o-phenylenediamine (PDA), 3,5-dinitrosalicylic acid (DNSA) and their charge transfer complex have been carried out at B3LYP/6-311G(d,p) level of theory. Molecular geometry and various other molecular properties like natural atomic charges, ionization potential, electron affinity, band gap, natural bond orbital (NBO) and frontier molecular analysis have been presented at same level of theory. Frontier molecular orbital and natural bond orbital analysis show the charge delocalization from PDA to DNSA. 16. Hydrogen-transfer and charge-transfer in photochemical and radiation induced reactions. Progress report, November 1, 1975--October 31, 1976 International Nuclear Information System (INIS) Cohen, S.G. 1976-10-01 The relative importance of light absorption, quenching of triplet, and hydrogen transfer repair has been examined in retardation by mercaptans of photoreduction of aromatic ketones by alcohols. In the reduction of benzophenone by 2-propanol, retardation is efficient and, after correction for the first two effects, is due entirely to hydrogen-transfer repair, as indicated by deuterium labeling. In reduction of acetophenone by α-methylbenzyl alcohol, repair by hydrogen transfer is also operative. In reduction of benzophenone by benzhydrol, retardation is less efficient and is due to quenching, as the ketyl radical does not abstract hydrogen from mercaptan rapidly in competition with coupling. Deuterium isotope effects are discussed in terms of competitive reactions. Photoreduction of benzophenone by 2-butylamine and by triethylamine is retarded by aromatic mercaptans and disulfides. Of the retardation not due to light absorption and triplet quenching by the sulfur compounds, half is due to hydrogen-transfer repair, as indicated by racemization and deuterium labeling. The remainder is attributed to quenching by the sulfur compound of the charge-transfer-complex intermediate. Photoreduction by primary and secondary amines, but not by tertiary amines, is accelerated by aliphatic mercaptans. The acceleration is attributed to catalysis of hydrogen transfer by the mercaptan in the charge-transfer complex. The effect is large in hydrocarbon solvent, less in polar organic solvents and absent in water 17. Laboratory estimation of net trophic transfer efficiencies of PCB congeners to lake trout (Salvelinus namaycush) from its prey Science.gov (United States) Madenjian, Charles P.; Rediske, Richard R.; O'Keefe, James P.; David, Solomon R. 2014-01-01 A technique for laboratory estimation of net trophic transfer efficiency (γ) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from their prey is described herein. During a 135-day laboratory experiment, we fed bloater (Coregonus hoyi) that had been caught in Lake Michigan to lake trout (Salvelinus namaycush) kept in eight laboratory tanks. Bloater is a natural prey for lake trout. In four of the tanks, a relatively high flow rate was used to ensure relatively high activity by the lake trout, whereas a low flow rate was used in the other four tanks, allowing for low lake trout activity. On a tank-by-tank basis, the amount of food eaten by the lake trout on each day of the experiment was recorded. Each lake trout was weighed at the start and end of the experiment. Four to nine lake trout from each of the eight tanks were sacrificed at the start of the experiment, and all 10 lake trout remaining in each of the tanks were euthanized at the end of the experiment. We determined concentrations of 75 PCB congeners in the lake trout at the start of the experiment, in the lake trout at the end of the experiment, and in bloaters fed to the lake trout during the experiment. Based on these measurements, γ was calculated for each of 75 PCB congeners in each of the eight tanks. Mean γ was calculated for each of the 75 PCB congeners for both active and inactive lake trout. Because the experiment was replicated in eight tanks, the standard error about mean γ could be estimated. Results from this type of experiment are useful in risk assessment models to predict future risk to humans and wildlife eating contaminated fish under various scenarios of environmental contamination. 18. Through space and through bridge channels of charge transfer at p-n nano-junctions: A DFT study Energy Technology Data Exchange (ETDEWEB) Dandu, Naveen [Department of Chemistry and Biochemistry, NDSU, Fargo, ND 58108 (United States); Tretiak, Sergei [Theoretical Division, Center for Nonlinear Studies (CNLS) and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, 57069, NM 87454 (United States); Kilina, Svetlana [Department of Chemistry and Biochemistry, NDSU, Fargo, ND 58108 (United States); Kilin, Dmitri, E-mail: Dmitri.Kilin@ndsu.edu [Department of Chemistry and Biochemistry, NDSU, Fargo, ND 58108 (United States) 2016-12-20 Highlights: • Properties of interacting QDs depend on the fashion of interaction: through-bond or through-space. • The disconnected and undoped dimer models shows FÓ§rster band formation. • Dimer models with some doping exhibit degenerate charge-transfer excitons. • p- and n-doped qds shows polarization at the interface. • A photoexcitation polarizes p-n interface, in relation to phototovoltaic effect. - Abstract: Details of charge density distribution at p-n nano interface are analyzed with density functional theory techniques using model system of dimers of doped silicon quantum dots interacting through bond and through space. Spatial distributions of transition densities between the ground and excited states suggest the character of essential electronic excitations, which have a FÓ§rster, bound, unbound, or charge transfer character. A redistribution of electronic density from n-impurities to p-impurities results in a ground state polarization and creates an offset of energies of the bands localized on p-doped quantum dot and the bands localized on n-doped quantum dot. Although impurities contribute very few orbitals to the total density, a ground state charge redistribution and polarization are both responsible for the presence of a large number of charge transfer excitations involving solely silicon orbitals. 19. Charge transfer effects, thermo and photochromism in single crystal CVD synthetic diamond. Science.gov (United States) Khan, R U A; Martineau, P M; Cann, B L; Newton, M E; Twitchen, D J 2009-09-09 We report on the effects of thermal treatment and ultraviolet irradiation on the point defect concentrations and optical absorption profiles of single crystal CVD synthetic diamond. All thermal treatments were below 850 K, which is lower than the growth temperature and unlikely to result in any structural change. UV-visible absorption spectroscopy measurements showed that upon thermal treatment (823 K), various broad absorption features diminished: an absorption band at 270 nm (used to deduce neutral single substitutional nitrogen (N(S)(0)) concentrations) and also two broad features centred at approximately 360 and 520 nm. Point defect centre concentrations as a function of temperature were also deduced using electron paramagnetic resonance (EPR) spectroscopy. Above ∼500 K, we observed a decrease in the concentration of N(S)(0) centres and a concomitant increase in the negatively charged nitrogen-vacancy-hydrogen (NVH) complex (NVH(-)) concentration. Both transitions exhibited an activation energy between 0.6 and 1.2 eV, which is lower than that for the N(S)(0) donor (∼1.7 eV). Finally, it was found that illuminating samples with intense short-wave ultraviolet light recovered the N(S)(0) concentration and also the 270, 360 and 520 nm absorption features. From these results, we postulate a valence band mediated charge transfer process between NVH and single nitrogen centres with an acceptor trap depth for NVH of 0.6-1.2 eV. Because the loss of N(S)(0) concentration is greater than the increase in NVH(-) concentration we also suggest the presence of another unknown acceptor existing at a similar energy to NVH. The extent to which the colour in CVD synthetic diamond is dependent on prior history is discussed. 20. Synthesis, growth, structural modeling and physio-chemical properties of a charge transfer molecule: Guanidinium tosylate Science.gov (United States) Era, Paavai; Jauhar, RO. MU.; Vinitha, G.; Murugakoothan, P. 2018-05-01 An organic nonlinear optical material, guanidinium tosylate was synthesized adopting slow evaporation method and the crystals were harvested from aqueous methanolic medium with dimensions 13 × 9 × 3 mm3. Constitution of crystalline material was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with space group P21/c. The UV-vis-NIR spectral study of the grown crystal exhibits high transparency of 80% in the entire visible region with lower cut-off wavelength at 282 nm. Optimized molecular geometry of the grown crystal was obtained using density functional theory (DFT) and the frontier energy gaps calculated from the DFT aids to understand the charge transfer taking place in the molecule. The dielectric properties were studied as a function of temperature and frequency to find the charge distribution within the crystal. The titular compound is thermally stable up to 230 °C assessed by thermogravimetric and differential thermal analysis. Anisotropy in the mechanical behavior was observed while measuring for individual planes. The laser induced surface damage threshold of the grown crystal was measured to be 0.344 GW/cm2 for 1064 nm Nd:YAG laser radiation. Z-scan technique confirms the third-order nonlinear optical property with the ascertained nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ(3)). Optical limiting study divulges that the transmitted output power step-up linearly with the increase of the input power at lower power realms and saturates from the threshold 24.95 mW/cm2 and amplitude 0.23 mW/cm2. 1. Evidence for excited state intramolecular charge transfer in benzazole-based pseudo-stilbenes. Science.gov (United States) Santos, Fabiano da Silveira; Descalzo, Rodrigo Roceti; Gonçalves, Paulo Fernando Bruno; Benvenutti, Edilson Valmir; Rodembusch, Fabiano Severo 2012-08-21 Two azo compounds were obtained through the diazotization reaction of aminobenzazole derivatives and N,N-dimethylaniline using clay montmorillonite KSF as catalyst. The synthesized dyes were characterized using elemental analysis, Fourier transform infrared spectroscopy, and (13)C and (1)H NMR spectroscopy in solution. Their photophysical behavior was studied using UV-vis and steady-state fluorescence in solution. These dyes present intense absorption in the blue region. The spectral features of the azo compounds can be related to the pseudo-stilbene type as well as the E isomer of the dyes. Excitation at the absorption maxima does not produce emissive species in the excited state. However, excitation around 350 nm allowed dual emission of fluorescence, from both a locally excited (LE, short wavelength) and an intramolecular charge transfer (ICT, long wavelength) state, which was corroborated by a linear relation of the fluorescence maximum (ν(max)) versus the solvent polarity function (Δf) from the Lippert-Mataga correlation. Evidence of TICT in these dyes was discussed from the viscosity dependence of the fluorescence intensity in the ICT emission band. Theoretical calculations were also performed in order to study the geometry and charge distribution of the dyes in their ground and excited electronic states. Using DFT methods at the theoretical levels BLYP/Aug-cc-pVDZ, for geometry optimizations and frequency calculations, and B3LYP/6-311+G(2d), for single-point energy evaluations, the calculations revealed that the least energetic and most intense photon absorption leads to a very polar excited state that relaxes non-radioactively, which can be associated with photochemical isomerization. 2. Organic charge transfer phase formation in thin films of the BEDT-TTF/TCNQ donor-acceptor system DEFF Research Database (Denmark) Solovyeva, Vita; Keller, K.; Huth, M. 2009-01-01 We have performed charge transfer phase formation studies on the donor/acceptor system bis-(ethylendithio)tetrathiafulvalene (BEDT-TTF)/tetracyanoquinodimethane,(TCNQ) by means of physical vapor deposition. We prepared donor/acceptor bilayer structures on glass and Si(100)/SiO substrates held... 3. Impact of exact exchange in the description of the electronic structure of organic charge-transfer molecular crystals KAUST Repository Fonari, Alexandr; Sutton, Christopher; Bredas, Jean-Luc; Coropceanu, Veaceslav 2014-01-01 in high-mobility organic crystals. We consider both crystals based on a single molecule, such as pentacene, and crystals based on mixed-stack charge-transfer systems, such as dibenzo-TTF–TCNQ. In the pentacene crystal, the band gap decreases 4. Determination of charge transfer resistance and capacitance of microbial fuel cell through a transient response analysis of cell voltage. Science.gov (United States) Ha, Phuc Thi; Moon, Hyunsoo; Kim, Byung Hong; Ng, How Yong; Chang, In Seop 2010-03-15 An alternative method for determining the charge transfer resistance and double-layer capacitance of microbial fuel cells (MFCs), easily implemented without a potentiostat, was developed. A dynamic model with two parameters, the charge transfer resistance and double-layer capacitance of electrodes, was derived from a linear differential equation to depict the current generation with respect to activation overvoltage. This model was then used to fit the transient cell voltage response to the current step change during the continuous operation of a flat-plate type MFC fed with acetate. Variations of the charge transfer resistance and the capacitance value with respect to the MFC design conditions (biocatalyst existence and electrode area) and operating parameters (acetate concentration and buffer strength in the catholyte) were then determined to elucidate the validity of the proposed method. This model was able to describe the dynamic behavior of the MFC during current change in the activation loss region; having an R(2) value of over 0.99 in most tests. Variations of the charge transfer resistance value (thousands of Omega) according to the change of the design factors and operational factors were well-correlated with the corresponding MFC performances. However, though the capacitance values (approximately 0.02 F) reflected the expected trend according to the electrode area change and catalyst property, they did not show significant variation with changes in either the acetate concentration or buffer strength. (c) 2009 Elsevier B.V. All rights reserved. 5. Theoretical and experimental study of charge transfer through DNA: Impact of mercury mediated T-Hg-T base pair Czech Academy of Sciences Publication Activity Database Kratochvílová, Irena; Vala, M.; Weiter, M.; Páv, Ondřej; Šebera, Jakub; Sychrovský, Vladimír 2015-01-01 Roč. 22, č. 1 (2015), s. 20 ISSN 1211-5894. [Discussions in Structural Molecular Biology. Annual Meeting of the Czech Society for Structural Biology /13./. 19.03.2015-21.03.2015, Nové Hrady] Institutional support: RVO:61388963 ; RVO:68378271 Keywords : charge transfer T-Hg-T * steady-state fluorescence Subject RIV: CF - Physical ; Theoretical Chemistry 6. Quasi-four-body treatment of charge transfer in the collision of protons with atomic helium: I. Thomas related mechanisms Science.gov (United States) 2018-04-01 The scattering of a completely bare ion by atoms larger than hydrogen is at least a four-body interaction, and the charge transfer channel involves a two-step process. Amongst the two-step interactions of the high-velocity single charge transfer in an anion-atom collision, there is one whose amplitude demonstrates a peak in the angular distribution of the cross sections. This peak, the so-called Thomas peak, was predicted by Thomas in a two-step interaction, classically, which could also be described through three-body quantum mechanical models. This work discusses a four-body quantum treatment of the charge transfer in ion-atom collisions, where two-step interactions illustrating a Thomas peak are emphasized. In addition, the Pauli exclusion principle is taken into account for the initial and final states as well as the operators. It will be demonstrated that there is a momentum condition for each two-step interaction to occur in a single charge transfer channel, where new classical interactions lead to the Thomas mechanism. 7. Charge transfer incollisions of Li3+ and Be4+ ions with atomic hydrogen at low impact energy International Nuclear Information System (INIS) Ohyama, T.; Itikawa, Y. 1981-08-01 Total charge transfer cross sections are calculated for the collisions of Li 3+ and Be 4+ ions with H(1s) atoms in the low energy region (E 3+ -H system, a reasonable agreement is found between the present calculation and the recent experiment. (author) 8. Turn-on fluorescence probes based on pyranine/viologen charge-transfer complexes for the determination of nucleotides Energy Technology Data Exchange (ETDEWEB) Schäferling, Michael, E-mail: Michael.schaeferling@utu.fi; Lang, Thomas; Schnettelker, Annette 2014-10-15 The formation of ground state charge-transfer complexes between pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid) and viologen (paraquat) derivatives is utilized for the design of novel fluoroionophores for the determination of phosphate species, particularly of nucleotides. The strong quenching of the pyranine fluorescence by viologen-type charge transfer acceptors can be countermanded if these are functionalized with triethylammonium groups that serve as recognition elements for phosphate anions. We report on the fluorogenic responses of these water-soluble molecular probes in presence of different phosphates. Absorbance measurements give additional information on the charge transfer complex formation and the interaction with nucleotides. The experimental data show that these aggregates form attractive, simple and versatile fluorescence turn-on probes for nucleoside triphosphates. The reversibility of the fluorescence response is demonstrated by means of an enzymatic model assay using ATPase for the decomposition of adenosine triphosphate. - Highlights: • Pyranine/viologen charge-transfer complexes as molecular probe for ATP recognition. • Fluorescence turn on mechanism. • Selective compared to other nucleotides and phosphate anions. • Fast and reversible response applicable to monitor enzymatic reactions. 9. Density functional calculations of potential energy surface and charge transfer integrals in molecular triphenylene derivative HAT6 NARCIS (Netherlands) Zbiri, M.; Johnson, M.R.; Kearley, G.J.; Mulder, F.M. 2009-01-01 We investigate the effect of structural fluctuations on charge transfer integrals, overlap integrals, and site energies in a system of two stacked molecular 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6), which is a model system for conducting devices in organic photocell applications. A density 10. Detection of Intramolecular Charge Transfer and Dynamic Solvation in Eosin B by Femtosecond Two-Dimensional Electronic Spectroscopy Science.gov (United States) Ghosh, Soumen; Roscioli, Jerome D.; Beck, Warren F. 2014-06-01 We have employed 2D electronic photon echo spectroscopy to study intramolecular charge-transfer dynamics in eosin B. After preparation of the first excited singlet state (S_1) with 40-fs excitation pulses at 520 nm, the nitro group (--NO_2) in eosin B undergoes excited state torsional motion towards a twisted intramolecular charge transfer (TICT) state. As the viscosity of the surrounding solvent increases, the charge-transfer rate decreases because the twisting of the --NO_2 group is hindered. These conclusions are supported by the time evolution of the 2D spectrum, which provides a direct measure of the the ground-to-excited-state energy gap time-correlation function, M(t). In comparison to the inertial and diffusive solvation time scales exhibited by eosin Y, which lacks the nitro group, the M(t) function for eosin B exhibits under the same conditions an additional component on the 150-fs timescale that arises from quenching of the S_1 state by crossing to the TICT state. These results indicate that 2D electronic spectroscopy can be used as a sensitive probe of the rate of charge transfer in a molecular system and of the coupling to the motions of the surrounding solvent. (Supported by grant DE-SC0010847 from the Department of Energy, Office of Basic Energy Sciences, Photosynthetic Systems program.) 11. Impact of exact exchange in the description of the electronic structure of organic charge-transfer molecular crystals KAUST Repository Fonari, Alexandr 2014-10-21 We evaluate the impact that the amount of nonlocal Hartree-Fock (%HF) exchange included in a hybrid density functional has on the microscopic parameters (transfer integrals, band gaps, bandwidths, and effective masses) describing charge transport in high-mobility organic crystals. We consider both crystals based on a single molecule, such as pentacene, and crystals based on mixed-stack charge-transfer systems, such as dibenzo-TTF–TCNQ. In the pentacene crystal, the band gap decreases and the effective masses increase linearly with an increase in the amount of %HF exchange. In contrast, in the charge-transfer crystals, while the band gap increases linearly, the effective masses vary only slightly with an increase in %HF exchange. We show that the superexchange nature of the electronic couplings in charge-transfer systems is responsible for this peculiar evolution of the effective masses. We compare the density functional theory results with results obtained within the G0W0 approximation as a way of benchmarking the optimal amount of %HF exchange needed in a given functional. 12. Identification of the site where the electron transfer chain of plant mitochondria is stimulated by electrostatic charge screening. NARCIS (Netherlands) Krab, K.; Wagner, M.J.; Wagner, A.M.; Moller, I.M. 2000-01-01 Modular kinetic analysis was used to determine the sites in plant mitochondria where charge-screening stimulates the rate of electron transfer from external NAD(P)H to oxygen. In mitochondria isolated from potato (Solanum tuberosum L.) tuber callus, stimulation of the rate of oxygen uptake was 13. 41 CFR 102-36.285 - May we charge for personal property transferred to another federal agency? Science.gov (United States) 2010-07-01 ... Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT... general fund of the Treasury or appropriated therefrom but by law reimbursable from assessment, tax, or... corporation. (b) You may charge for direct costs you incurred incident to the transfer, such as packing... 14. An intramolecular charge transfer state of carbonyl carotenoids: implications for excited state dynamics of apo-carotenals and retinal Czech Academy of Sciences Publication Activity Database Polívka, Tomáš; Kaligotla, S.; Chábera, P.; Frank, H.A. 2011-01-01 Roč. 13, č. 22 (2011), s. 1463-9076 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z50510513 Keywords : carotenoid * retinal * excited-state dynamics * charge-transfer state Subject RIV: BO - Biophysics Impact factor: 3.573, year: 2011 15. Strong isotope effects on the charge transfer in slow collisions of He2+ with atomic hydrogen, deuterium, and tritium NARCIS (Netherlands) Stolterfoht, N.; Cabrera-Trujillo, R.; Oehrn, Y.; Deumens, E.; Hoekstra, R.; Sabin, J. R. 2007-01-01 Probabilities and cross sections for charge transfer by He2+ impact on atomic hydrogen (H), deuterium (D), and tritium (T) at low collision energies are calculated. The results are obtained using an ab initio theory, which solves the time-dependent Schrodinger equation. For the H target, excellent 16. Coherence, energy and charge transfers in de-excitation pathways of electronic excited state of biomolecules in photosynthesis DEFF Research Database (Denmark) Bohr, Henrik; Malik, F. Bary 2013-01-01 The observed multiple de-excitation pathways of photo-absorbed electronic excited state in the peridinin–chlorophyll complex, involving both energy and charge transfers among its constituents, are analyzed using the bio-Auger (B-A) theory. It is also shown that the usually used F¨orster–Dexter... 17. Charge versus Energy Transfer Effects in High-Performance Perylene Diimide Photovoltaic Blend Films. Science.gov (United States) Singh, Ranbir; Shivanna, Ravichandran; Iosifidis, Agathaggelos; Butt, Hans-Jürgen; Floudas, George; Narayan, K S; Keivanidis, Panagiotis E 2015-11-11 Perylene diimide (PDI)-based organic photovoltaic devices can potentially deliver high power conversion efficiency values provided the photon energy absorbed is utilized efficiently in charge transfer (CT) reactions instead of being consumed in nonradiative energy transfer (ET) steps. Hitherto, it remains unclear whether ET or CT primarily drives the photoluminescence (PL) quenching of the PDI excimer state in PDI-based blend films. Here, we affirm the key role of the thermally assisted PDI excimer diffusion and subsequent CT reaction in the process of PDI excimer PL deactivation. For our study we perform PL quenching experiments in the model PDI-based composite made of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2-6-diyl] (PBDTTT-CT) polymeric donor mixed with the N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. Despite the strong spectral overlap between the PDI excimer PL emission and UV-vis absorption of PBDTTT-CT, two main observations indicate that no significant ET component operates in the overall PL quenching: the PL intensity of the PDI excimer (i) increases with decreasing temperature and (ii) remains unaffected even in the presence of 10 wt % content of the PBDTTT-CT quencher. Temperature-dependent wide-angle X-ray scattering experiments further indicate that nonradiative resonance ET is highly improbable due to the large size of PDI domains. The dominance of the CT over the ET process is verified by the high performance of devices with an optimum composition of 30:70 PBDTTT-CT:PDI. By adding 0.4 vol % of 1,8-diiodooctane we verify the plasticization of the polymer side chains that balances the charge transport properties of the PBDTTT-CT:PDI composite and results in additional improvement in the device efficiency. The temperature-dependent spectral width of the PDI excimer PL band suggests the presence of energetic disorder in the 18. Accurate determination of the charge transfer efficiency of photoanodes for solar water splitting. Science.gov (United States) Klotz, Dino; Grave, Daniel A; Rothschild, Avner 2017-08-09 The oxygen evolution reaction (OER) at the surface of semiconductor photoanodes is critical for photoelectrochemical water splitting. This reaction involves photo-generated holes that oxidize water via charge transfer at the photoanode/electrolyte interface. However, a certain fraction of the holes that reach the surface recombine with electrons from the conduction band, giving rise to the surface recombination loss. The charge transfer efficiency, η t , defined as the ratio between the flux of holes that contribute to the water oxidation reaction and the total flux of holes that reach the surface, is an important parameter that helps to distinguish between bulk and surface recombination losses. However, accurate determination of η t by conventional voltammetry measurements is complicated because only the total current is measured and it is difficult to discern between different contributions to the current. Chopped light measurement (CLM) and hole scavenger measurement (HSM) techniques are widely employed to determine η t , but they often lead to errors resulting from instrumental as well as fundamental limitations. Intensity modulated photocurrent spectroscopy (IMPS) is better suited for accurate determination of η t because it provides direct information on both the total photocurrent and the surface recombination current. However, careful analysis of IMPS measurements at different light intensities is required to account for nonlinear effects. This work compares the η t values obtained by these methods using heteroepitaxial thin-film hematite photoanodes as a case study. We show that a wide spread of η t values is obtained by different analysis methods, and even within the same method different values may be obtained depending on instrumental and experimental conditions such as the light source and light intensity. Statistical analysis of the results obtained for our model hematite photoanode show good correlation between different methods for 19. CoPc and CoPcF16 on gold: Site-specific charge-transfer processes Directory of Open Access Journals (Sweden) Fotini Petraki 2014-04-01 Full Text Available Interface properties of cobalt(II phthalocyanine (CoPc and cobalt(II hexadecafluoro-phthalocyanine (CoPcF16 to gold are investigated by photo-excited electron spectroscopies (X-ray photoemission spectroscopy (XPS, ultraviolet photoemission spectroscopy (UPS and X-ray excited Auger electron spectroscopy (XAES. It is shown that a bidirectional charge transfer determines the interface energetics for CoPc and CoPcF16 on Au. Combined XPS and XAES measurements allow for the separation of chemical shifts based on different local charges at the considered atom caused by polarization effects. This facilitates a detailed discussion of energetic shifts of core level spectra. The data allow the discussion of site-specific charge-transfer processes. 20. Influence of Coherent Tunneling and Incoherent Hopping on the Charge Transfer Mechanism in Linear Donor-Bridge-Acceptor Systems. Science.gov (United States) Li, Guangqi; Govind, Niranjan; Ratner, Mark A; Cramer, Christopher J; Gagliardi, Laura 2015-12-17 The mechanism of charge transfer has been observed to change from tunneling to hopping with increasing numbers of DNA base pairs in polynucleotides and with the length of molecular wires. The aim of this paper is to investigate this transition by examining the population dynamics using a tight-binding Hamiltonian with model parameters to describe a linear donor-bridge-acceptor (D-B-A) system. The model includes a primary vibration and an electron-vibration coupling at each site. A further coupling of the primary vibration with a secondary phonon bath allows the system to dissipate energy to the environment and reach a steady state. We apply the quantum master equation (QME) approach, based on second-order perturbation theory in a quantum dissipative system, to examine the dynamical processes involved in charge-transfer and follow the population transfer rate at the acceptor, ka, to shed light on the transition from tunneling to hopping. With a small tunneling parameter, V, the on-site population tends to localize and form polarons, and the hopping mechanism dominates the transfer process. With increasing V, the population tends to be delocalized and the tunneling mechanism dominates. The competition between incoherent hopping and coherent tunneling governs the mechanism of charge transfer. By varying V and the total number of sites, we also examine the onset of the transition from tunneling to hopping with increasing length. 1. A model for the chain-to-plane charge transfer in YBa2Cu3O6+x International Nuclear Information System (INIS) Matic, V. M.; Lazarov, N. Dj.; Milic, M. 2012-01-01 A model for the chain-to-plane charge transfer is proposed to account for the two plateaus, at 60 K and at 90 K, of the T c (x) characteristics of the YBa 2 Cu 3 O 6+x high-T c superconductor. It is assumed that the number of holes transferred from a CuO chain of length l to two nearby CuO 2 sheets is proportional to l (that is, to the number of oxygen atoms in the chain), if the chain length is greater than, or equal to, a certain critical chain length, l cr , that is required to trigger the charge transfer process. No holes are assumed to have been transferred from chains of length l cr . The calculated T c (x) dependence is found to be in excellent agreement with the experimentally reported T c (x). The critical chain length parameter is estimated to be equal to l cr = 11 (eleven oxygen atoms in a chain), which is a greater value than that obtained in the previously proposed model for the chain-to-plane charge transfer (l cr = 4). The results obtained out of the proposed model are briefly discussed 2. Neutralized ion beam modification of cellulose membranes for study of ion charge effect on ion-beam-induced DNA transfer Science.gov (United States) Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D. 2012-02-01 Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment. 3. Four- and six-charge transfer reactions induced by 52Cr, 56Fe, 63Cu in rare-earths International Nuclear Information System (INIS) Mouchaty, G. 1977-01-01 The cross sections for transfer reactions in which 4 and 6 charges are gained by Sm and Nd targets have been measured, the projectiles being 52 Cr and 56 Fe at 343 and 377 MeV. These energies correspond to 1.5B, B being the interaction barrier. The results obtained indicate that the cross section increases when the number of charges transferred and the mass of the projectile are increased. The angular distributions and recoil ranges at each angle of 151 Dy produced through 52 Cr+ 148 Sm, 52 Cr+ 144 Nd, 56 Fe+ 144 Nd, 63 Cu+ 144 Nd reactions were determined for incident energies equivalent to 1.5B. After transformation into the c.m. system, the angular distributions exhibit a maximum close to 155 0 and a tail at small angles. The position of the maximum is independent of the incident ion and of the number of transferred charges. The analysis of the energy distributions indicate that the observed reactions can be explained by a two-step process: a transfer of nucleons followed by an evaporation step. The number of nucleons transferred in the 1st step and the associated excitation energies are higher for the events corresponding to the tail than for those corresponding to the maximum [fr 4. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads KAUST Repository Jiang, Junlin 2017-05-25 A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers. 5. Effect of Conjugation Length on Photoinduced Charge-Transfer in π-Conjugated Oligomer-Acceptor Dyads KAUST Repository Jiang, Junlin; Alsam, Amani Abdu; Wang, Shanshan; Aly, Shawkat Mohammede; Pan, Zhenxing; Mohammed, Omar F.; Schanze, Kirk S. 2017-01-01 A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1.1 and G0CR ~ -2.0 eV), and the driving forces do not vary much across the series because the oxidation and reduction potentials and singlet energies of the OPEs do not vary much with their length. Bimolecular photoinduced charge transfer between model OPEs that do not contain the NDI acceptors with methyl viologen was studied, and the results reveal that the absorption of the cation radical state (OPE+•) remains approximately constant ( ~ 575 nm) regardless of oligomer length. This finding suggests that the cation radical (polaron) of the OPE is relatively localized, effectively occupying a confined segment of n 4 repeat units in the longer oligomers. Photoinduced intramolecular electron transfer dynamics in the PEn-NDI series was investigated by UV-visible femtosecond transient absorption spectroscopy with visible and mid-infrared probes. Charge separation occurs on the 1 – 10 ps timescale, with the rates decreasing slightly with increased oligomer length (βCS ~ 0.15 Å-1). The rate for charge-recombination decreases in the sequence PE4-NDI > PE6-NDI ~ PE8-NDI. The discontinuous distance dependence in the rate for charge recombination may be related to the spatial localization of the positive polaron state in the longer oligomers. 6. Coupled quantum-classical method for long range charge transfer: relevance of the nuclear motion to the quantum electron dynamics International Nuclear Information System (INIS) Da Silva, Robson; Hoff, Diego A; Rego, Luis G C 2015-01-01 Charge and excitonic-energy transfer phenomena are fundamental for energy conversion in solar cells as well as artificial photosynthesis. Currently, much interest is being paid to light-harvesting and energy transduction processes in supramolecular structures, where nuclear dynamics has a major influence on electronic quantum dynamics. For this reason, the simulation of long range electron transfer in supramolecular structures, under environmental conditions described within an atomistic framework, has been a difficult problem to study. This work describes a coupled quantum mechanics/molecular mechanics method that aims at describing long range charge transfer processes in supramolecular systems, taking into account the atomistic details of large molecular structures, the underlying nuclear motion, and environmental effects. The method is applied to investigate the relevance of electron–nuclei interaction on the mechanisms for photo-induced electron–hole pair separation in dye-sensitized interfaces as well as electronic dynamics in molecular structures. (paper) 7. Influence of the zero point oscillation on the charge transfer in the heavy-ion deep inelastic collisions Energy Technology Data Exchange (ETDEWEB) Lin-xiao, Ge; Wen-qing, Shen; Chao-fan, Yu 1982-01-01 We discuss the variance of the charge distribution in the heavy ion deep inelastic collision on the basis of the Langevin equation. In order to explain the difference of the inital slope (early stage) of the charge distribution for the different reaction systems and different bombarding energy, an initial condition of the charge drift in the early stage of Dic is introduced. It is given by the harmonic or inhamonic motion around the zero point and closely depends on the nuclear structure and incident energy. The difference of the inertial mass and stiffness parameter may be the one of the reasons for the difference of charge transfer. In addition we also analyse the characterstic of the inertial mass parameter. 8. Crystalline structure of the marketed form of Rifampicin: a case of conformational and charge transfer polymorphism Science.gov (United States) de Pinho Pessoa Nogueira, Luciana; de Oliveira, Yara S.; de C. Fonseca, Jéssica; Costa, Wendell S.; Raffin, Fernanda N.; Ellena, Javier; Ayala, Alejandro Pedro 2018-03-01 Rifampicin is a semi-synthetic drug derived from rifamycin B, and currently integrates the fixed dose combination tablet formulations used in the treatment of tuberculosis. It is also used in the leprosy polychemotherapy and prophylaxis, which are diseases classified as neglected according to the World Health Organization. Rifampicin is a polymorphic drug and its desirable polymorphic form is labeled as II, being the main goal of this study the elucidation of its crystalline structure. Polymorph II is characterized by two molecules with different conformations in the asymmetric unit and the following lattice parameters: a = 14.0760 (10) Å, b = 17.5450 (10) Å, c = 17.5270 (10) Å, β = 92.15°. Differently to the previously reported structures, a charge transference from the hydroxyl group of the naphthoquinone of one conformer to the nitrogen of the piperazine group of the second conformer was observed. The relevance of the knowledge of this crystalline structure, which is the preferred polymorph for pharmaceutical formulations, was evidenced by analyzing raw materials with polymorphic mixtures. Thus, the results presented in this contribution close an old information gap allowing the complete solid-state characterization of rifampicin. 9. Electronic coupling effects and charge transfer between organic molecules and metal surfaces Energy Technology Data Exchange (ETDEWEB) Forker, Roman 2010-07-01 We employ a variant of optical absorption spectroscopy, namely in situ differential reflectance spectroscopy (DRS), for an analysis of the structure-properties relations of thin epitaxial organic films. Clear correlations between the spectra and the differently intense coupling to the respective substrates are found. While rather broad and almost structureless spectra are obtained for a quaterrylene (QT) monolayer on Au(111), the spectral shape resembles that of isolated molecules when QT is grown on graphite. We even achieve an efficient electronic decoupling from the subjacent Au(111) by inserting an atomically thin organic spacer layer consisting of hexa-peri-hexabenzocoronene (HBC) with a noticeably dissimilar electronic behavior. These observations are further consolidated by a systematic variation of the metal substrate (Au, Ag, and Al), ranging from inert to rather reactive. For this purpose, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) is chosen to ensure comparability of the molecular film structures on the different metals, and also because its electronic alignment on various metal surfaces has previously been studied with great intensity. We present evidence for ionized PTCDA at several interfaces and propose the charge transfer to be related to the electronic level alignment governed by interface dipole formation on the respective metals. (orig.) 10. Protein-induced geometric constraints and charge transfer in bacteriochlorophyll-histidine complexes in LH2. Science.gov (United States) Wawrzyniak, Piotr K; Alia, A; Schaap, Roland G; Heemskerk, Mattijs M; de Groot, Huub J M; Buda, Francesco 2008-12-14 Bacteriochlorophyll-histidine complexes are ubiquitous in nature and are essential structural motifs supporting the conversion of solar energy into chemically useful compounds in a wide range of photosynthesis processes. A systematic density functional theory study of the NMR chemical shifts for histidine and for bacteriochlorophyll-a-histidine complexes in the light-harvesting complex II (LH2) is performed using the BLYP functional in combination with the 6-311++G(d,p) basis set. The computed chemical shift patterns are consistent with available experimental data for positive and neutral(tau) (N(tau) protonated) crystalline histidines. The results for the bacteriochlorophyll-a-histidine complexes in LH2 provide evidence that the protein environment is stabilizing the histidine close to the Mg ion, thereby inducing a large charge transfer of approximately 0.5 electronic equivalent. Due to this protein-induced geometric constraint, the Mg-coordinated histidine in LH2 appears to be in a frustrated state very different from the formal neutral(pi) (N(pi) protonated) form. This finding could be important for the understanding of basic functional mechanisms involved in tuning the electronic properties and exciton coupling in LH2. 11. Charge transfer and ionization in collisions of Si3+ with H from low to high energy Science.gov (United States) Wang, J. G.; He, B.; Ning, Y.; Liu, C. L.; Yan, J.; Stancil, P. C.; Schultz, D. R. 2006-11-01 Charge transfer processes due to collisions of ground state Si3+(3sS1) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) and classical-trajectory Monte Carlo (CTMC) methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained from Herrero [J. Phys. B 29, 5583 (1996)] which were calculated with a full configuration-interaction method. Total and state-selective single-electron capture cross sections are obtained for collision energies from 0.01eV/u to 1MeV/u . Total and state-selective rate coefficients are also presented for temperatures from 2×103K to 107K . Comparison with existing data reveals that the total CTMC cross sections are in good agreement with the experimental measurements at the higher considered energies and that previous Landau-Zener calculations underestimate the total rate coefficients by a factor of up to two. The CTMC calculations of target ionization are presented for high energies. 12. Charge transfer and ionization in collisions of Si3+ with H from low to high energy International Nuclear Information System (INIS) Wang, J. G.; He, B.; Ning, Y.; Liu, C. L.; Yan, J.; Stancil, P. C.; Schultz, D. R. 2006-01-01 Charge transfer processes due to collisions of ground state Si 3+ (3s 1 S) ions with atomic hydrogen are investigated using the quantum-mechanical molecular-orbital close-coupling (MOCC) and classical-trajectory Monte Carlo (CTMC) methods. The MOCC calculations utilize ab initio adiabatic potentials and nonadiabatic radial coupling matrix elements obtained from Herrero et al. [J. Phys. B 29, 5583 (1996)] which were calculated with a full configuration-interaction method. Total and state-selective single-electron capture cross sections are obtained for collision energies from 0.01 eV/u to 1 MeV/u. Total and state-selective rate coefficients are also presented for temperatures from 2x10 3 K to 10 7 K. Comparison with existing data reveals that the total CTMC cross sections are in good agreement with the experimental measurements at the higher considered energies and that previous Landau-Zener calculations underestimate the total rate coefficients by a factor of up to two. The CTMC calculations of target ionization are presented for high energies 13. Controllable Charge Transfer in Ag-TiO2 Composite Structure for SERS Application Directory of Open Access Journals (Sweden) Yaxin Wang 2017-06-01 Full Text Available The nanocaps array of TiO2/Ag bilayer with different Ag thicknesses and co-sputtering TiO2-Ag monolayer with different TiO2 contents were fabricated on a two-dimensional colloidal array substrate for the investigation of Surface enhanced Raman scattering (SERS properties. For the TiO2/Ag bilayer, when the Ag thickness increased, SERS intensity decreased. Meanwhile, a significant enhancement was observed when the sublayer Ag was 10 nm compared to the pure Ag monolayer, which was ascribed to the metal-semiconductor synergistic effect that electromagnetic mechanism (EM provided by roughness surface and charge-transfer (CT enhancement mechanism from TiO2-Ag composite components. In comparison to the TiO2/Ag bilayer, the co-sputtered TiO2-Ag monolayer decreased the aggregation of Ag particles and led to the formation of small Ag particles, which showed that TiO2 could effectively inhibit the aggregation and growth of Ag nanoparticles. 14. Temperature-dependent vibrational spectroscopy to study order-disorder transitions in charge transfer complexes Directory of Open Access Journals (Sweden) Rohan Isaac 2018-02-01 Full Text Available Charge-transfer (CT complexes are a promising class of materials for the semiconductor industry because of their versatile properties. This class of compounds shows a variety of phase transitions, which are of interest because of their potential impact on the electronic characteristics. Here temperature-dependent vibrational spectroscopy is used to study structural phase transitions in a set of organic CT complexes. Splitting and broadening of infrared-active phonons in the complex formed between pyrene and pyromellitic dianhydride (PMDA confirm the structural transition is of the order-disorder type and complement previous x-ray diffraction (XRD results. We show that this technique is a powerful tool to characterize transitions, and apply it to a range of binary CT complexes composed of polyaromatic hyrdocarbons (anthracene, perylene, phenanthrene, pyrene, and stilbene and PMDA. We extend the understanding of transitions in perylene-PMDA and pyrene-PMDA, and show that there are no order-disorder transitions present in anthracene-PMDA, stilbene-PMDA and phenanthrene-PMDA in the temperature range investigated here. 15. Temperature-dependent vibrational spectroscopy to study order-disorder transitions in charge transfer complexes Science.gov (United States) Isaac, Rohan; Goetz, Katelyn P.; Roberts, Drew; Jurchescu, Oana D.; McNeil, L. E. 2018-02-01 Charge-transfer (CT) complexes are a promising class of materials for the semiconductor industry because of their versatile properties. This class of compounds shows a variety of phase transitions, which are of interest because of their potential impact on the electronic characteristics. Here temperature-dependent vibrational spectroscopy is used to study structural phase transitions in a set of organic CT complexes. Splitting and broadening of infrared-active phonons in the complex formed between pyrene and pyromellitic dianhydride (PMDA) confirm the structural transition is of the order-disorder type and complement previous x-ray diffraction (XRD) results. We show that this technique is a powerful tool to characterize transitions, and apply it to a range of binary CT complexes composed of polyaromatic hyrdocarbons (anthracene, perylene, phenanthrene, pyrene, and stilbene) and PMDA. We extend the understanding of transitions in perylene-PMDA and pyrene-PMDA, and show that there are no order-disorder transitions present in anthracene-PMDA, stilbene-PMDA and phenanthrene-PMDA in the temperature range investigated here. 16. Geometry and quadratic nonlinearity of charge transfer complexes in solution: A theoretical study International Nuclear Information System (INIS) Mukhopadhyay, S.; Ramasesha, S.; Pandey, Ravindra; Das, Puspendu K. 2011-01-01 In this paper, we have computed the quadratic nonlinear optical (NLO) properties of a class of weak charge transfer (CT) complexes. These weak complexes are formed when the methyl substituted benzenes (donors) are added to strong acceptors like chloranil (CHL) or di-chloro-di-cyano benzoquinone (DDQ) in chloroform or in dichloromethane. The formation of such complexes is manifested by the presence of a broad absorption maximum in the visible range of the spectrum where neither the donor nor the acceptor absorbs. The appearance of this visible band is due to CT interactions, which result in strong NLO responses. We have employed the semiempirical intermediate neglect of differential overlap (INDO/S) Hamiltonian to calculate the energy levels of these CT complexes using single and double configuration interaction (SDCI). The solvent effects are taken into account by using the self-consistent reaction field (SCRF) scheme. The geometry of the complex is obtained by exploring different relative molecular geometries by rotating the acceptor with respect to the fixed donor about three different axes. The theoretical geometry that best fits the experimental energy gaps, β HRS and macroscopic depolarization ratios is taken to be the most probable geometry of the complex. Our studies show that the most probable geometry of these complexes in solution is the parallel displaced structure with a significant twist in some cases. 17. Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity. Science.gov (United States) Qi, Zewan; Chen, Yang 2017-01-15 Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb 3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H + is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb 3+ . The long luminescence lifetime of Tb 3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H + in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands. Copyright Â© 2016 Elsevier B.V. All rights reserved. 18. Analysis of Charge Transfer for in Situ Li Intercalated Carbon Nanotubes KAUST Repository Rana, Kuldeep 2012-05-24 Vertically aligned carbon nanotube (VA-CNT) arrays have been synthesized with lithium (Li) intercalation through an alcohol-catalyzed chemical vapor deposition technique by using a Li-containing catalyst. Scanning electron microscopy images display that synthesized carbon nanotubes (CNTs) are dense and vertically aligned. The effect of the Li-containing catalyst on VA-CNTs has been studied by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). XPS results show the change in binding energy of Li 1s and C 1s peaks, which indicates that Li is inserted in VA-CNTs during growth. Analysis of Raman spectra reveals that the G-band profile of CNTs synthesized with the Li-containing catalyst is shifted, suggesting an electronic interaction between Li and neighboring C atoms of the CNTs. The EELS spectra of the C K edge and Li K edge from CNTs also confirmed that Li is inserted into CNTs during synthesis. We have performed ab inito calculations based on density functional theory for a further understanding of the structural and electronic properties of Li intercalated CNTs, especially addressing the controversial charge-transfer state between Li and C. © 2012 American Chemical Society. 19. Graphene oxide based photoinduced charge transfer label-free near-infrared fluorescent biosensor for dopamine. Science.gov (United States) Chen, Jin-Long; Yan, Xiu-Ping; Meng, Kang; Wang, Shu-Feng 2011-11-15 While the super fluorescence quenching capacity of graphene and graphene oxide (GO) has been extensively employed to develop fluorescent sensors, their own unique fluorescence and its potential for chemo-/biosensing have seldom been explored. Here we report a GO-based photoinduced charge transfer (PCT) label-free near-infrared (near-IR) fluorescent biosensor for dopamine (DA). The multiple noncovalent interactions between GO and DA and the ultrafast decay at the picosecond range of the near-IR fluorescence of GO resulted in effective self-assembly of DA molecules on the surface of GO, and significant fluorescence quenching, allowing development of a PCT-based biosensor with direct readout of the near-IR fluorescence of GO for selective and sensitive detection of DA. The developed method gave a detection limit of 94 nM and a relative standard deviation of 2.0% for 11 replicate detections of 2.0 μM DA and was successfully applied to the determination of DA in biological fluids with quantitative recovery (98-115%). 20. Spectroscopy and dynamics of charge transfer excitons in type-II band aligned quantum confined heterostructures Energy Technology Data Exchange (ETDEWEB) Kushavah, Dushyant [Centre for Research in Nanotechnology and Science, IIT Bombay-400076, Mumbai (India); Mohapatra, P. K.; Vasa, P.; Singh, B. P., E-mail: bhanups@iitb.ac.in [Department of physics, IIT Bombay, Mumbai-400076 (India); Rustagi, K. C. [Indian Institute of Science Education and Research Bhopal-462066, Bhopal (India); Bahadur, D. [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai-400076 (India) 2015-05-15 We illustrate effect of charge transfer (CT) in type-II quantum confined heterostructure by comparing CdSe quantum dots (QDs), CdSe/CdTe heterostructure quantum dots (HQDs) and CdSe/CdTe/CdSe quantum well-quantum dots (QWQDs) heterostructures. CdSe core QDs were synthesized using a kinetic growth method where QD size depends on reaction time. For shell coating we used modified version of successive ionic layer adsorption and reaction (SILAR). Size of different QDs ∼5 to 7 nm were measured by transmission electron microscopy (TEM). Strong red shift from ∼597 to ∼746 nm in photoluminescence (PL) spectra from QDs to QWQDs shows high tunability which is not possible with single constituent semiconductor QDs. PL spectra have been recorded at different temperatures (10K-300K). Room temperature time correlated single photon counting (TCSPC) measurements for QDs to QWQDs show three exponential radiative decay. The slowest component decay constant in QWQDs comes around eight fold to ∼51 ns as compared to ∼6.5 ns in HQD suggesting new opportunities to tailor the radiative carrier recombination rate of CT excitons. 1. Spectrophotometric determination and thermodynamic studies of the charge transfer complexes of azelastine-HCl Directory of Open Access Journals (Sweden) Nahla N. Salama 2011-06-01 Full Text Available Three charge transfer complexes of azelastine as n-donor with π acceptors, dichloro-dicyanobenzoquinone (DDQ, chloranilic acid (CA and tetracyanoquinodimethane (TCNQ were prepared in acetonitrile. They yield a radical anions measured at 456, 520 and 841 nm within concentration ranges of 8.0–72, 40–320 and 1.6–14.4 μg mL−1 with good correlation coefficients (r = 0.9996–0.9998. The molar absorptivities and association constants for the colored products were evaluated using the Benesi–Hildebrand equation. The free energy change (ΔG0 and the enthalpy of formation (ΔH0 as well as the entropy (ΔS0 were determined for the reaction product with TCNQ. The methods were successfully applied to the analysis of azelastine in its pharmaceutical preparations, where no interferences could be observed from the additives commonly present in the eye drops or nasal spray as proved by good mean recoveries of 98.89 ± 1.06–99.54 ± 1.84%. The results were compared, favorably with the manufacturer method and validated according to ICH guidelines. 2. Charge transfer interaction using quasiatomic minimal-basis orbitals in the effective fragment potential method International Nuclear Information System (INIS) Xu, Peng; Gordon, Mark S. 2013-01-01 The charge transfer (CT) interaction, the most time-consuming term in the general effective fragment potential method, is made much more computationally efficient. This is accomplished by the projection of the quasiatomic minimal-basis-set orbitals (QUAMBOs) as the atomic basis onto the self-consistent field virtual molecular orbital (MO) space to select a subspace of the full virtual space called the valence virtual space. The diagonalization of the Fock matrix in terms of QUAMBOs recovers the canonical occupied orbitals and, more importantly, gives rise to the valence virtual orbitals (VVOs). The CT energies obtained using VVOs are generally as accurate as those obtained with the full virtual space canonical MOs because the QUAMBOs span the valence part of the virtual space, which can generally be regarded as “chemically important.” The number of QUAMBOs is the same as the number of minimal-basis MOs of a molecule. Therefore, the number of VVOs is significantly smaller than the number of canonical virtual MOs, especially for large atomic basis sets. This leads to a dramatic decrease in the computational cost 3. Photosynthesis Revisited: Optimization of Charge and Energy Transfer in Quantum Materials Science.gov (United States) Gabor, Nathaniel 2014-03-01 The integration of new nano- and molecular-scale quantum materials into ultra-efficient energy harvesting devices presents significant scientific challenges. Of the many challenges, the most difficult is achieving high photon-to-electron conversion efficiency while maintaining broadband absorption. Due to exciton effects, devices composed of quantum materials may allow near-unity optical absorption efficiency yet require the choice of precisely one fundamental energy (HOMO-LUMO gap). To maximize absorption, the simplest device would absorb at the peak of the solar spectrum, which spans the visible wavelengths. If the peak of the solar spectrum spans the visible wavelengths, then why are terrestrial plants green? Here, I discuss a physical model of photosynthetic absorption and photoprotection in which the cell utilizes active feedback to optimize charge and energy transfer, thus maximizing stored energy rather than absorption. This model, which addresses the question of terrestrial greenness, is supported by several recent results that have begun to unravel the details of photoprotection in higher plants. More importantly, this model indicates a novel route for the design of next-generation energy harvesting systems based on nano- and molecular-scale quantum materials. 4. Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics KAUST Repository Mora-Sero, Ivan; Bertoluzzi, Luca; Gonzalez-Pedro, Victoria; Gimenez, Sixto; Fabregat-Santiago, Francisco; Kemp, Kyle W.; Sargent, Edward H.; Bisquert, Juan 2013-01-01 Colloidal quantum dot solar cells achieve spectrally selective optical absorption in a thin layer of solution-processed, size-effect tuned, nanoparticles. The best devices built to date have relied heavily on drift-based transport due to the action of an electric field in a depletion region that extends throughout the thickness of the quantum dot layer. Here we study for the first time the behaviour of the best-performing class of colloidal quantum dot films in the absence of an electric field, by screening using an electrolyte. We find that the action of selective contacts on photovoltage sign and amplitude can be retained, implying that the contacts operate by kinetic preferences of charge transfer for either electrons or holes. We develop a theoretical model to explain these experimental findings. The work is the first to present a switch in the photovoltage in colloidal quantum dot solar cells by purposefully formed selective contacts, opening the way to new strategies in the engineering of colloidal quantum dot solar cells. © 2013 Macmillan Publishers Limited. All rights reserved. 5. Optically active charge transfer in hybrids of Alq3 nanoparticles and MoS2 monolayer Science.gov (United States) Ghimire, Ganesh; Dhakal, Krishna P.; Neupane, Guru P.; Jo, Seong Gi; Kim, Hyun; Seo, Changwon; Lee, Young Hee; Joo, Jinsoo; Kim, Jeongyong 2017-05-01 Organic/inorganic hybrid structures have been widely studied because of their enhanced physical and chemical properties. Monolayers of transition metal dichalcogenides (1L-TMDs) and organic nanoparticles can provide a hybridization configuration between zero- and two-dimensional systems with the advantages of convenient preparation and strong interface interaction. Here, we present such a hybrid system made by dispersing π-conjugated organic (tris (8-hydroxyquinoline) aluminum(III)) (Alq3) nanoparticles (NPs) on 1L-MoS2. Hybrids of Alq3 NP/1L-MoS2 exhibited a two-fold increase in the photoluminescence of Alq3 NPs on 1L-MoS2 and the n-doping effect of 1L-MoS2, and these spectral and electronic modifications were attributed to the charge transfer between Alq3 NPs and 1L-MoS2. Our results suggested that a hybrid of organic NPs/1L-TMD can offer a convenient platform to study the interface interactions between organic and inorganic nano objects and to engineer optoelectronic devices with enhanced performance. 6. Simultaneous spectrophotometric determination of trimethoprim and sulphamethoxazole following charge-transfer complexation with chloranilic acid Directory of Open Access Journals (Sweden) 2017-05-01 Full Text Available A simple, accurate and precise simultaneous spectrophotometric method has been developed for the analysis of trimethoprim–sulphamethoxazole combination in pure and tablet dosage forms. The method involves direct charge transfer complexation of trimethoprim (TMP with chloranilic acid (CAA in acetonitrile–dioxane solvent mixture and complexation of sulphamethoxazole (SMZ after its hydrolysis in dilute H2SO4. Optimization of temperature and time revealed the superiority of room temperature and 20 and 30 min respectively for TMP and SMZ. Optimal detector responses were obtained at 520 and 440 nm and were therefore selected as working wavelength maxima for SMZ and TMP respectively. TMP and hydrolysed SMZ were combined with CAA at mole ratios of 1:1 and 1:3 respectively. Accuracies were generally less than 4% (estimated as degree of inaccuracy or error with a precision of the order of less than 2% on a three-day assessment. Physicochemical factors responsible for complex stability were estimated and related to the observed data. The method was successfully applied to the determination of TMP and SMZ in tablet dosage forms with accuracies comparable to the official BP method. There were no interferences from common tablet excipients and TMP complex did not interfere with the assay of SMZ. The developed method could find application in routine quality control of TMP–SMZ combination. It is the first reported full simultaneous colorimetric assay of TMP and SMZ using the same analytical reagent. 7. Strategies for Efficient Charge Separation and Transfer in Artificial Photosynthesis of Solar Fuels. Science.gov (United States) Xu, Yuxing; Li, Ailong; Yao, Tingting; Ma, Changtong; Zhang, Xianwen; Shah, Jafar Hussain; Han, Hongxian 2017-11-23 Converting sunlight to solar fuels by artificial photosynthesis is an innovative science and technology for renewable energy. Light harvesting, photogenerated charge separation and transfer (CST), and catalytic reactions are the three primary steps in the processes involved in the conversion of solar energy to chemical energy (SE-CE). Among the processes, CST is the key "energy pump and delivery" step in determining the overall solar-energy conversion efficiency. Efficient CST is always high priority in designing and assembling artificial photosynthesis systems for solar-fuel production. This Review not only introduces the fundamental strategies for CST but also the combinatory application of these strategies to five types of the most-investigated semiconductor-based artificial photosynthesis systems: particulate, Z-scheme, hybrid, photoelectrochemical, and photovoltaics-assisted systems. We show that artificial photosynthesis systems with high SE-CE efficiency can be rationally designed and constructed through combinatory application of these strategies, setting a promising blueprint for the future of solar fuels. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. 8. Antibacterial activity of large-area monolayer graphene film manipulated by charge transfer. Science.gov (United States) Li, Jinhua; Wang, Gang; Zhu, Hongqin; Zhang, Miao; Zheng, Xiaohu; Di, Zengfeng; Liu, Xuanyong; Wang, Xi 2014-03-12 Graphene has attracted increasing attention for potential applications in biotechnology due to its excellent electronic property and biocompatibility. Here we use both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) to investigate the antibacterial actions of large-area monolayer graphene film on conductor Cu, semiconductor Ge and insulator SiO2. The results show that the graphene films on Cu and Ge can surprisingly inhibit the growth of both bacteria, especially the former. However, the proliferation of both bacteria cannot be significantly restricted by the graphene film on SiO2. The morphology of S. aureus and E. coli on graphene films further confirms that the direct contact of both bacteria with graphene on Cu and Ge can cause membrane damage and destroy membrane integrity, while no evident membrane destruction is induced by graphene on SiO2. From the viewpoint of charge transfer, a plausible mechanism is proposed here to explain this phenomenon. This study may provide new insights for the better understanding of antibacterial actions of graphene film and for the better designing of graphene-based antibiotics or other biomedical applications. 9. Absence of Intramolecular Singlet Fission in Pentacene-Perylenediimide Heterodimers: The Role of Charge Transfer State. Science.gov (United States) Wang, Long; Wu, Yishi; Chen, Jianwei; Wang, Lanfen; Liu, Yanping; Yu, Zhenyi; Yao, Jiannian; Fu, Hongbing 2017-11-16 A new class of donor-acceptor heterodimers based on two singlet fission (SF)-active chromophores, i.e., pentacene (Pc) and perylenediimide (PDI), was developed to investigate the role of charge transfer (CT) state on the excitonic dynamics. The CT state is efficiently generated upon photoexcitation. However, the resulting CT state decays to different energy states depending on the energy levels of the CT state. It undergoes extremely rapid deactivation to the ground state in polar CH 2 Cl 2 , whereas it undergoes transformation to a Pc triplet in nonpolar toluene. The efficient triplet generation in toluene is not due to SF but CT-mediated intersystem crossing. In light of the energy landscape, it is suggested that the deep energy level of the CT state relative to that of the triplet pair state makes the CT state actually serve as a trap state that cannot undergoes an intramolecular singlet fission process. These results provide guidance for the design of SF materials and highlight the requisite for more widely applicable design principles. 10. Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics KAUST Repository Mora-Sero, Ivan 2013-08-12 Colloidal quantum dot solar cells achieve spectrally selective optical absorption in a thin layer of solution-processed, size-effect tuned, nanoparticles. The best devices built to date have relied heavily on drift-based transport due to the action of an electric field in a depletion region that extends throughout the thickness of the quantum dot layer. Here we study for the first time the behaviour of the best-performing class of colloidal quantum dot films in the absence of an electric field, by screening using an electrolyte. We find that the action of selective contacts on photovoltage sign and amplitude can be retained, implying that the contacts operate by kinetic preferences of charge transfer for either electrons or holes. We develop a theoretical model to explain these experimental findings. The work is the first to present a switch in the photovoltage in colloidal quantum dot solar cells by purposefully formed selective contacts, opening the way to new strategies in the engineering of colloidal quantum dot solar cells. © 2013 Macmillan Publishers Limited. All rights reserved. 11. The thermochromic behavior of aromatic amine-SO2 charge transfer complexes Science.gov (United States) Monezi, Natália M.; Borin, Antonio C.; Santos, Paulo S.; Ando, Rômulo A. 2017-02-01 The distinct thermochromism observed in solutions containing N,N-dimethylaniline (DMA) and N,N-diethylaniline (DEA) and SO2 was investigated by resonance Raman spectroscopy in a wide range of temperatures. The results indicate in addition to the charge transfer (CT) complexes DMA-SO2 and DEA-SO2, the presence of collision complexes involving the CT complexes and excess DMA and DEA molecules. The latter in fact is the chromophore responsible for the long wavelength absorption originating the color. The Raman signature of the collision complex was attributed to the distinct enhancement of a band at 1140 cm- 1 assigned to νs(SO2), in contrast to the same mode in the 1:1 complex at 1115 cm- 1. The intensity of such band, assigned to the collision complex is favored at high temperatures and depends on the steric hindrance associated to amines, as well as the SO2 molar fraction. Quantum chemical calculations based on time-dependent density functional theory (TDDFT) support the proposed interpretation. 12. Analysis of Charge Transfer for in Situ Li Intercalated Carbon Nanotubes KAUST Repository Rana, Kuldeep; Kucukayan-Dogu, Gokce; Sen, H. Sener; Boothroyd, Chris; Gulseren, Oguz; Bengu, Erman 2012-01-01 Vertically aligned carbon nanotube (VA-CNT) arrays have been synthesized with lithium (Li) intercalation through an alcohol-catalyzed chemical vapor deposition technique by using a Li-containing catalyst. Scanning electron microscopy images display that synthesized carbon nanotubes (CNTs) are dense and vertically aligned. The effect of the Li-containing catalyst on VA-CNTs has been studied by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). XPS results show the change in binding energy of Li 1s and C 1s peaks, which indicates that Li is inserted in VA-CNTs during growth. Analysis of Raman spectra reveals that the G-band profile of CNTs synthesized with the Li-containing catalyst is shifted, suggesting an electronic interaction between Li and neighboring C atoms of the CNTs. The EELS spectra of the C K edge and Li K edge from CNTs also confirmed that Li is inserted into CNTs during synthesis. We have performed ab inito calculations based on density functional theory for a further understanding of the structural and electronic properties of Li intercalated CNTs, especially addressing the controversial charge-transfer state between Li and C. © 2012 American Chemical Society. 13. High pressure study of high temperatures superconductors: Material base, universal Tc-behavior, and charge transfer International Nuclear Information System (INIS) Chu, C.W.; Hor, P.H.; Lin, J.G.; Xiong, Q.; Huang, Z.J.; Meng, R.L.; Xue, Y.Y.; Jean, Y.C. 1991-01-01 The superconducting transition temperature (T c ) has been measured in YBa 2 Cu 3 O 6.7 , YBa 2 Cu 3 O 7 , Y 2 Ba 4 Cu 7 O 15 , YBa 2 Cu 4 O 8 , Tl 2 Ba 2 Ca n-1 Cu n O n+4-δ , La 2-x Sr x CuO 4 , and La 2-x Ba x CuO 4 under high pressures. The pressure effect on the positron lifetime (τ) has also been determined in the first four compounds. Based on these and other high pressure data, the authors suggest that (1) all known cuprate high temperature superconductors (HTS's) may be no more than mere modifications of either 214-T, 214-T', 123, or a combination of 214-T' and 123, (2) a nonmonotonic T c -behavior may govern the T c -variation of all hole cuprate HTS's and (3) pressure can induce charge transfer leading to a T c -change. The implications of these suggestions will also be discussed 14. Multiple Electron Charge Transfer Chemistries for Electrochemical Energy Storage Systems: The Metal Boride and Metal Air Battery Science.gov (United States) Stuart, Jessica F. The primary focus of this work has been to develop high-energy capacity batteries capable of undergoing multiple electron charge transfer redox reactions to address the growing demand for improved electrical energy storage systems that can be applied to a range of applications. As the levels of carbon dioxide (CO2) increase in the Earth's atmosphere, the effects on climate change become increasingly apparent. According to the Energy Information Administration (EIA), the U.S. electric power sector is responsible for the release of 2,039 million metric tons of CO2 annually, equating to 39% of total U.S. energy-related CO2 emissions. Both nationally and abroad, there are numerous issues associated with the generation and use of electricity aside from the overwhelming dependence on fossil fuels and the subsequent carbon emissions, including reliability of the grid and the utilization of renewable energies. Renewable energy makes up a relatively small portion of total energy contributions worldwide, accounting for only 13% of the 3,955 billion kilowatt-hours of electricity produced each year, as reported by the EIA. As the demand to reduce our dependence on fossils fuels and transition to renewable energy sources increases, cost effective large-scale electrical energy storage must be established for renewable energy to become a sustainable option for the future. A high capacity energy storage system capable of leveling the intermittent nature of energy sources such as solar, wind, and water into the electric grid and provide electricity at times of high demand will facilitate this transition. In 2008, the Licht Group presented the highest volumetric energy capacity battery, the vanadium diboride (VB2) air battery, exceedingly proficient in transferring eleven electrons per molecule. This body of work focuses on new developments to this early battery such as fundamentally understanding the net discharge mechanism of the system, evaluation of the properties and 15. Strategies to enhance the excitation energy-transfer efficiency in a light-harvesting system using the intra-molecular charge transfer character of carotenoids Energy Technology Data Exchange (ETDEWEB) Yukihira, Nao [Department of Applied Chemistry for Environment; School of Science and Technology; Kwansei Gakuin University; Sanda; Japan; Sugai, Yuko [Department of Applied Chemistry for Environment; School of Science and Technology; Kwansei Gakuin University; Sanda; Japan; Fujiwara, Masazumi [Department of Applied Chemistry for Environment; School of Science and Technology; Kwansei Gakuin University; Sanda; Japan; Kosumi, Daisuke [Institute of Pulsed Power Science; Kumamoto University; Kumamoto; Japan; Iha, Masahiko [South Product Co. Ltd.; Uruma-shi; Japan; Sakaguchi, Kazuhiko [Department of Chemistry; Graduate School of Science; Osaka City University; Osaka 558-8585; Japan; Katsumura, Shigeo [Department of Chemistry; Graduate School of Science; Osaka City University; Osaka 558-8585; Japan; Gardiner, Alastair T. [Glasgow Biomedical Research Centre; University of Glasgow; 126 University Place; Glasgow, G12 8QQ; UK; Cogdell, Richard J. [Glasgow Biomedical Research Centre; University of Glasgow; 126 University Place; Glasgow, G12 8QQ; UK; Hashimoto, Hideki [Department of Applied Chemistry for Environment; School of Science and Technology; Kwansei Gakuin University; Sanda; Japan 2017-01-01 Fucoxanthin is a carotenoid that is mainly found in light-harvesting complexes from brown algae and diatoms. Due to the presence of a carbonyl group attached to polyene chains in polar environments, excitation produces an excited intra-molecular charge transfer. This intra-molecular charge transfer state plays a key role in the highly efficient (~95%) energy-transfer from fucoxanthin to chlorophyllain the light-harvesting complexes from brown algae. In purple bacterial light-harvesting systems the efficiency of excitation energy-transfer from carotenoids to bacteriochlorophylls depends on the extent of conjugation of the carotenoids. In this study we were successful, for the first time, in incorporating fucoxanthin into a light-harvesting complex 1 from the purple photosynthetic bacterium,Rhodospirillum rubrumG9+ (a carotenoidless strain). Femtosecond pump-probe spectroscopy was applied to this reconstituted light-harvesting complex in order to determine the efficiency of excitation energy-transfer from fucoxanthin to bacteriochlorophyllawhen they are bound to the light-harvesting 1 apo-proteins. 16. Frenkel and Charge-Transfer Excitations in Donor-acceptor Complexes from Many-Body Green's Functions Theory. Science.gov (United States) Baumeier, Björn; Andrienko, Denis; Rohlfing, Michael 2012-08-14 Excited states of donor-acceptor dimers are studied using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. For a series of prototypical small-molecule based pairs, this method predicts energies of local Frenkel and intermolecular charge-transfer excitations with the accuracy of tens of meV. Application to larger systems is possible and allowed us to analyze energy levels and binding energies of excitons in representative dimers of dicyanovinyl-substituted quarterthiophene and fullerene, a donor-acceptor pair used in state of the art organic solar cells. In these dimers, the transition from Frenkel to charge transfer excitons is endothermic and the binding energy of charge transfer excitons is still of the order of 1.5-2 eV. Hence, even such an accurate dimer-based description does not yield internal energetics favorable for the generation of free charges either by thermal energy or an external electric field. These results confirm that, for qualitative predictions of solar cell functionality, accounting for the explicit molecular environment is as important as the accurate knowledge of internal dimer energies. 17. An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals Directory of Open Access Journals (Sweden) Parul Chawla 2014-08-01 Full Text Available In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO and tri-n-octylphosphine (TOP and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-ordered 3-dimensional network in its pristine form exhibit a higher steric- and photo-stability, resistance against coagulation and homogeneity compared to the CISe and CIGSe counterparts. Moreover, CZTSe nanocrystallites display efficient photoluminescence quenching as evident from the high value of the Stern–Volmer quenching constant (KSV and eventually higher charge transfer efficiency in their respective polymer P3HT:CZTSe composites. We modelled the dependency of the charge transfer from the donor and the charge separation mechanism across the donor–acceptor interface from the extent of crystallinity of the chalcopyrite semiconductors (CISe/CIGSe/CZTSe. Quaternary CZTSe chalcopyrites with their high crystallinity and controlled morphology in conjunction with regioregular P3HT polymer is an attractive candidate for hybrid solar cells applications. 18. The simplest equivalent circuit of a pulsed dielectric barrier discharge and the determination of the gas gap charge transfer Science.gov (United States) Pipa, A. V.; Koskulics, J.; Brandenburg, R.; Hoder, T. 2012-11-01 The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge qmax, and (iii) the development of a graphical method for the determination of qmax from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of qmax is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current jR(t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance Cd. Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the Cd is important. 19. Modeling the effect of shunt current on the charge transfer efficiency of an all-vanadium redox flow battery Science.gov (United States) Chen, Yong-Song; Ho, Sze-Yuan; Chou, Han-Wen; Wei, Hwa-Jou 2018-06-01 In an all-vanadium redox flow battery (VRFB), a shunt current is inevitable owing to the electrically conductive electrolyte that fills the flow channels and manifolds connecting cells. The shunt current decreases the performance of a VRFB stack as well as the energy conversion efficiency of a VRFB system. To understand the shunt-current loss in a VRFB stack with various designs and operating conditions, a mathematical model is developed to investigate the effects of the shunt current on battery performance. The model is calibrated with experimental data under the same operating conditions. The effects of the battery design, including the number of cells, state of charge (SOC), operating current, and equivalent resistance of the electrolytes in the flow channels and manifolds, on the shunt current are analyzed and discussed. The charge-transfer efficiency is calculated to investigate the effects of the battery design parameters on the shunt current. When the cell number is increased from 5 to 40, the charge transfer efficiency is decreased from 0.99 to a range between 0.76 and 0.88, depending on operating current density. The charge transfer efficiency can be maintained at higher than 0.9 by limiting the cell number to less than 20. 20. An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals. Science.gov (United States) Chawla, Parul; Singh, Son; Sharma, Shailesh Narain 2014-01-01 In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe) chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO) and tri-n-octylphosphine (TOP) and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene) polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-ordered 3-dimensional network in its pristine form exhibit a higher steric- and photo-stability, resistance against coagulation and homogeneity compared to the CISe and CIGSe counterparts. Moreover, CZTSe nanocrystallites display efficient photoluminescence quenching as evident from the high value of the Stern-Volmer quenching constant (K SV) and eventually higher charge transfer efficiency in their respective polymer P3HT:CZTSe composites. We modelled the dependency of the charge transfer from the donor and the charge separation mechanism across the donor-acceptor interface from the extent of crystallinity of the chalcopyrite semiconductors (CISe/CIGSe/CZTSe). Quaternary CZTSe chalcopyrites with their high crystallinity and controlled morphology in conjunction with regioregular P3HT polymer is an attractive candidate for hybrid solar cells applications. 1. Charge transfer in low-energy collisions of H with He+ and H+ with He in excited states Science.gov (United States) Loreau, J.; Ryabchenko, S.; Muñoz Burgos, J. M.; Vaeck, N. 2018-04-01 The charge transfer process in collisions of excited (n = 2, 3) hydrogen atoms with He+ and in collisions of excited helium atoms with H+ is studied theoretically. A combination of a fully quantum-mechanical method and a semi-classical approach is employed to calculate the charge-exchange cross sections at collision energies from 0.1 eV u‑1 up to 1 keV u‑1. These methods are based on accurate ab initio potential energy curves and non-adiabatic couplings for the molecular ion HeH+. Charge transfer can occur either in singlet or in triplet states, and the differences between the singlet and triplet spin manifolds are discussed. The dependence of the cross section on the quantum numbers n and l of the initial state is demonstrated. The isotope effect on the charge transfer cross sections, arising at low collision energy when H is substituted by D or T, is investigated. Rate coefficients are calculated for all isotopes up to 106 K. Finally, the impact of the present calculations on models of laboratory plasmas is discussed. 2. The simplest equivalent circuit of a pulsed dielectric barrier discharge and the determination of the gas gap charge transfer International Nuclear Information System (INIS) Pipa, A. V.; Brandenburg, R.; Hoder, T.; Koskulics, J. 2012-01-01 The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge q max , and (iii) the development of a graphical method for the determination of q max from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of q max is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the discharge current j R (t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance C d . Whereas for quantitative evaluation of electrical measurements, the accurate estimation of the C d is important. 3. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals International Nuclear Information System (INIS) 2013-01-01 Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL 4. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals Energy Technology Data Exchange (ETDEWEB) 2013-11-08 Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL 5. Electrosynthesis of Copper-Tetracyanoquinodimethane Based on the Coupling Charge Transfer across Water/1,2-Dichloroethane Interface International Nuclear Information System (INIS) Huang, Li; Li, Pei; Pamphile, Ndagijimana; Tian, Zhong-Qun; Zhan, Dongping 2014-01-01 Graphical abstract: - Highlights: • Organic semiconductor CuTCNQ is synthesized through electrochemistry of liquid/liquid interface. • A coupling charge transfer (CCT) mechanism is proposed for organic electrosynthesis. • The obtained CuTCNQ has good electrochemical and electronic properties. - Abstract: The organic salt Copper-Tetracyanoquinodimethane (CuTCNQ) is an important semiconductor used in electronics for field-effect transistors, switches and memory devices. Here we present a novel electrosynthetic method of CuTCNQ microneedles based on the coupling charge transfer across water/1,2-dichloroethane (W/1,2-DCE) interface. A HOPG electrode is covered by a small volume of 1,2-DCE solution, which is further covered by an aqueous solution to construct the W/1,2-DCE interface. When TCNQ in 1,2-DCE phase is reduced on HOPG, Cu 2+ in the aqueous solution will transfer across the W/1,2-DCE interface in order to maintain the electric neutrality. Therein CuTCNQ microneedles are formed which have good solid-state electrochemical and electronic properties. This coupling charge transfer mechanism is valuable and broadens the applications of liquid/liquid interface in organic electrosynthesis 6. Intense charge transfer surface based on graphene and thymine-Hg(II)-thymine base pairs for detection of Hg(2.). Science.gov (United States) Li, Jiao; Lu, Liping; Kang, Tianfang; Cheng, Shuiyuan 2016-03-15 In this article, we developed an electrochemiluminescence (ECL) sensor with a high-intensity charge transfer interface for Hg(2+) detection based on Hg(II)-induced DNA hybridization. The sensor was fabricated by the following simple method. First, graphene oxide (GO) was electrochemically reduced onto a glassy carbon electrode through cyclic voltammetry. Then, amino-labeled double-stranded (ds)DNA was assembled on the electrode surface using 1-pyrenebutyric acid N-hydroxysuccinimide as a linker between GO and DNA. The other terminal of dsDNA, which was labeled with biotin, was linked to CdSe quantum dots via biotin-avidin interactions. Reduced graphene oxide has excellent electrical conductivity. dsDNA with T-Hg(II)-T base pairs exhibited more facile charge transfer. They both accelerate the electron transfer performance and sensitivity of the sensor. The increased ECL signals were logarithmically linear with the concentration of Hg(II) when Hg(2+) was present in the detection solution. The linear range of the sensor was 10(-11) to 10(-8)mol/L (R=0.9819) with a detection limit of 10(-11)mol/L. This biosensor exhibited satisfactory results when it was used to detect Hg(II) in real water samples. The biosensor with high-intense charge transfer performance is a prospect avenue to pursue more and more sensitive detection method. Copyright © 2015 Elsevier B.V. All rights reserved. 7. Moessbauer effect study of charge and spin transfer in Fe-Cr International Nuclear Information System (INIS) Dubiel, S.M.; Zukrowski, J. 1981-01-01 The influence of temperature and time of annealing on hyperfine fields and isomer shifts has been studied for a range of Fe-Cr alloys containing 1-45 at% Cr. It has been revealed that up to 15 at% Cr neither time or temperature of annealing practically does affect the hyperfine parameters. For more concentrated samples, however, both temperature and time of annealing are important. In particular, the Moessbauer spectrum of Fe-45.5 at% Cr annealed at 700 0 C for 5 h was a single-line indicating that the sample was paramagnetic. The observed changes of the hyperfine fields and the isomer shifts have been interpreted in terms of a spin and charge transfer, respectively. Strong linear correlations between the following quantities have been revealed: the hyperfine field H(0,0) and the isomer shift IS(0,0); the average hyperfine field anti H and the average isomer shift anti Ianti S; the average hyperfine field anti H and the average number of Cr atoms in the first two coordination spheres, anti N. It has been calculated from the first two correlations that a) a change of polarization of itinerant s-like electrons of one electron is equivalent to a change of the hyperfine field of 1602 kOe, and b) on average, a unit change of s-like electron polarization is equivalent to 3277 kOe. The two constants are very close to theoretical estimations, which can be found in literature. Correlation between the hyperfine field and the isomer shift led to a conclusion that the substitution of Fe atoms by Cr ones decreases the density of spin-up electrons on average by 0.026 electrons per one Cr atom in a unit cell. These electrons are most likely trapped by Cr atoms, because the hyperfine field at neighbouring Fe nuclei decreases and the density of charge at those nuclei increases at the rate of 0.029 electrons per one Cr atom in a unit cell. (orig./BHO) 8. CNDO/2-SCF and PCILO (MO) calculations on the 1-butene/NA/and (charge-transfer) complex Energy Technology Data Exchange (ETDEWEB) Lochmann, R; Meiler, W 1977-01-01 CNDO/2-SCF and PCILO (MO) calculations on the 1-Butene/Na/sup +/ (charge-transfer) complex involving the olefinic m electrons were made in connection with butene adsorption in zeolites, including the effect of the cation on the conformation of the butene in the zeolite cavity. Calculations were made of rotational energy barriers, preferred cation arrangements with respect to the butene molecule, and charge distributions by both methods. Taking into account systematic errors with the two methods, it is concluded that the PCILO method, which predicts a stabilization of the skew over the cis conformation by the cation, gives closer agreement with experiment. Graph, tables, diagrams, and 19 references. 9. Charge transfer and rapidity gap analysis in p(π+)n interactions at 195 GeV/c International Nuclear Information System (INIS) Eisenberg, Y.; Haber, B.; Hochmann, D.; Karshon, U.; Ronat, E.E.; Shapira, A.; Yekutieli, G. 1980-01-01 We present charge transfer probabilities between CM hemispheres in pn and π + n interactions at 195 GeV/c. The relative probabilities for charge exchanges ΔQ > 1 as a function of rapidity gap length, r, are given. Both results are compared with those of π - p interactions at 200 GeV/c. The average of r, viz. , is given as a function of the gap number and of ΔQ for various multiplicities, and the reduced average gap lengths /ysub(max) for pn interactions are compared with data at a lower energy. (orig.) 10. Twisted intra-molecular charge transfer investigations of semiorganic triglycine phosphate single crystal for non linear optical applications Science.gov (United States) Meera, M. R.; Joselin Beaula, T.; Rayar, S. L.; Bena Jothy, V. 2017-09-01 NLO materials are gaining importance in technologies such as optical communication, optical computing and dynamic image processing. Many NLO crystals grown by mixing amino acids with various organic and inorganic acids have been reported in the literature. Hence, glycine mixed semi-organic material will be of special interest as a fundamental building block to develop many complex crystals with improved NLO properties. A semi organic Single crystal of Triglycine Phosphate (TGP) which was grown and spectral analysis have been using FTIR and Raman spectral analysis. Natural Bond Orbital Analysis and the atomic natural charges are also predicted. HOMO LUMO energy gap value suggests the possibility of charge transfer within the molecule. 11. Charge transfer and band bending at Au/Pb(Zr0.2Ti0.8)O3 interfaces investigated by photoelectron spectroscopy International Nuclear Information System (INIS) Apostol, Nicoleta G.; Stoflea, Laura E.; Lungu, George A.; Chirila, Cristina; Trupina, Lucian; Negrea, Raluca F.; Ghica, Corneliu; Pintilie, Lucian; Teodorescu, Cristian M. 2013-01-01 The growth of gold layers on Pb(Zr,Ti)O 3 (PZT) deposited on SrTiO 3 is investigated by X-ray photoelectron spectroscopy in the Au thickness range 2–100 Å. Two phases are identified, with compositions close to nominal PZT. The ‘standard’ phase is represented by all binding energies (Pb 4f, Ti 2p, Zr 3d, O 1s) sensibly equal to the nominal values for PZT, whereas the ‘charged’ phase exhibits all core levels are shifted by ∼1 eV toward higher binding energies. By taking into account also scanning probe microscopy images together with recent photoemission results, the ‘charged’ phase belongs to P (+) regions of PZT, whereas the ‘normal’ phase corresponds to regions with no net ferroelectric polarization perpendicular to the surface. Au deposition proceeds in a band bending of Φ PZT − Φ Au ∼ 0.4–0.5 eV for both phases, identified as similar shifts toward higher binding energies of all Pb, Ti, Zr, O core levels with Au deposition. The Au 4f core level exhibits also an unusually low binding energy component 1 eV below the ‘nominal’ Au 4f binding energy position (metal Au). This implies the existence of negatively charged gold, or electron transfer from PZT to Au, although the ‘normal’ PZT phase have a higher work function, as it is derived from the band bending. Most probably this charge transfer occurs toward Au nanoparticles, which have even higher ionization energies. High resolution transmission electron microscopy evidenced the formation of such isolated nanoparticles. 12. Wireless Energy Transfer Using Resonant Magnetic Induction for Electric Vehicle Charging Application Science.gov (United States) Dahal, Neelima The research work for this thesis is based on utilizing resonant magnetic induction for wirelessly charging electric vehicles. The background theory for electromagnetic induction between two conducting loops is given and it is shown that an RLCequivalent circuit can be used to model the loops. An analysis of the equivalent circuit is used to show how two loosely coupled loops can be made to exchange energy efficiently by operating them at a frequency which is the same as the resonant frequency of both. Furthermore, it is shown that the efficiency is the maximum for critical coupling (determined by the quality factors of the loops), and increasing the coupling beyond critical coupling causes double humps to appear in the transmission efficiency versus frequency spectrum. In the experiment, as the loops are brought closer together which increases the coupling between them, doubles humps, as expected from the equivalent circuit analysis is seen. Two models for wireless energy transfer are identified: basic model and array model. The basic model consists of the two loosely coupled loops, the transmitter and the receiver. The array model consists of a 2 x 2 array of the transmitter and three parasites, and the receiver. It is shown that the array model allows more freedom for receiver placement at the cost of degraded transmission efficiency compared to the basic model. Another important part of the thesis is software validation. HFSS-IE and 4NEC2 are the software tools used and the simulation results for wire antennas are compared against references obtained from a textbook and a PhD dissertation. It is shown that the simulations agree well with the references and also with each other. 13. Electronic structure, charge transfer, and intrinsic luminescence of gadolinium oxide nanoparticles: Experiment and theory Science.gov (United States) Zatsepin, D. A.; Boukhvalov, D. W.; Zatsepin, A. F.; Kuznetsova, Yu. A.; Mashkovtsev, M. A.; Rychkov, V. N.; Shur, V. Ya.; Esin, A. A.; Kurmaev, E. Z. 2018-04-01 The cubic (c) and monoclinic (m) polymorphs of Gd2O3 were studied using the combined analysis of several materials science techniques - X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. Density functional theory (DFT) based calculations for the samples under study were performed as well. The cubic phase of gadolinium oxide (c-Gd2O3) synthesized using a precipitation method exhibits spheroidal-like nanoclusters with well-defined edges assembled from primary nanoparticles with an average size of 50 nm, whereas the monoclinic phase of gadolinium oxide (m-Gd2O3) deposited using explosive pyrolysis has a denser structure compared with natural gadolinia. This phase also has a structure composed of three-dimensional complex agglomerates without clear-edged boundaries that are ∼21 nm in size plus a cubic phase admixture of only 2 at.% composed of primary edge-boundary nanoparticles ∼15 nm in size. These atomic features appear in the electronic structure as different defects ([Gd…Osbnd OH] and [Gd…Osbnd O]) and have dissimilar contributions to the charge-transfer processes among the appropriate electronic states with ambiguous contributions in the Gd 5р - O 2s core-like levels in the valence band structures. The origin of [Gd…Osbnd OH] defects found by XPS was well-supported by PL analysis. The electronic and atomic structures of the synthesized gadolinias calculated using DFT were compared and discussed on the basis of the well-known joint OKT-van der Laan model, and good agreement was established. 14. Ab initio study of charge transfer between lithium and aromatic hydrocarbons. Can the results be directly transferred to the lithium-graphene interaction? Science.gov (United States) 2014-08-28 We have used electronic density calculations to study neutral complexes of Li with aromatic hydrocarbons. The charge transferred between a Li atom and benzene, coronene, circumcoronene, and circumcircumcoronene has been studied by ab initio methods (at the HF and MP2 level). Toward this aim, the method of integrating electron density in two cuboid fragments of space was applied. One of the fragments was constructed so that it enclosed the bulk of the electron density of lithium; the second, the bulk of the electron density of hydrocarbon. It was found that for each complex two conformations were identified: the most stable with a greater vertical Li-hydrocarbon distance, on the order of 2.5 Å, and another of higher energy with a corresponding distance less than 2 Å. In all cases the transfer of a fractional number, 0.1-0.3 electrons, between Li and hydrocarbon was found; however, the direction of the transfer was not the same in all complexes investigated. The structures of complexes of the first configuration could be represented as Li(σ-)···AH(σ+), whereas the opposite direction of charge transfer was found for complexes of the second configuration, with higher energy. The directions of the dipole moments in the complexes supported these conclusions because they directly measure the redistribution of electron density in a complex with respect to substrates. 15. Design and characteristic investigations of superconducting wireless power transfer for electric vehicle charging system via resonance coupling method Energy Technology Data Exchange (ETDEWEB) Chung, Y. D. [Suwon Science College, Suwon (Korea, Republic of); Yim, Seung Woo [Dept. of Korea Electric Power Corporation Research Institute, Daejeon (Korea, Republic of) 2014-09-15 As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz. 16. Design and characteristic investigations of superconducting wireless power transfer for electric vehicle charging system via resonance coupling method International Nuclear Information System (INIS) Chung, Y. D.; Yim, Seung Woo 2014-01-01 As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz 17. Degree of phase separation effects on the charge transfer properties of P3HT:Graphene nanocomposites International Nuclear Information System (INIS) Bkakri, R.; Kusmartseva, O.E.; Kusmartsev, F.V.; Song, M.; Bouazizi, A. 2015-01-01 Graphene layers were introduced into the matrix of regioregular poly (3-hexylthiophene-2, 5-diyl) (RR-P3HT) via solution processing in the perspective of the development of organic nanocomposites with high P3HT/Graphene interfaces areas for efficient charge transfer process. P3HT and graphene act as electrons donor and electrons acceptor materials, respectively. Spatial Fourier Transforms (FFT) and power spectral density (PSD) analysis of the AFM images show that the phase separation decreases with increasing the graphene weight ratio in the P3HT matrix. The Raman spectra of the P3HT:Graphene nanocomposites shows that the G-band of graphene shifts to low frequencies with progressive addition of graphene which proves that there is an interaction between the nanowires of P3HT and the graphene layers. We suggest that the shift of the G-band is due to electrons transfer from P3HT to graphene. The quenching of the photoluminescence (PL) intensity of P3HT with addition of graphene proves also that an electrons transfer process occurred at the P3HT/Graphene interfaces. - Highlights: • Graphene layers are elaborated from expandable graphite oxide. • The effects of the graphene doping level on the charge transfer process were studied. • The phase separation process decreases with increasing the graphene content in the P3HT matrix. • Quenching of the PL intensity is due to electrons transfer from P3HT to graphene 18. Charge-Transfer Dynamics in the Lowest Excited State of a Pentacene–Fullerene Complex: Implications for Organic Solar Cells KAUST Repository Joseph, Saju 2017-10-02 We characterize the dynamic nature of the lowest excited state in a pentacene/C60 complex on the femtosecond time scale, via a combination of ab initio molecular dynamics and time-dependent density functional theory. We analyze the correlations between the molecular vibrations of the complex and the oscillations in the electron-transfer character of its lowest excited state, which point to vibration-induced coherences between the (pentacene-based) local-excitation (LE) state and the complex charge-transfer (CT) state. We discuss the implications of our results on this model system for the exciton-dissociation process in organic solar cells. 19. Altering intra- to inter-molecular hydrogen bonding by dimethylsulfoxide: A TDDFT study of charge transfer for coumarin 343 Science.gov (United States) Liu, Xiaochun; Yin, Hang; Li, Hui; Shi, Ying 2017-04-01 DFT and TDDFT methods were carried out to investigate the influences of intramolecular and intermolecular hydrogen bonding on excited state charge transfer for coumarin 343 (C343). Intramolecular hydrogen bonding is formed between carboxylic acid group and carbonyl group in C343 monomer. However, in dimethylsulfoxide (DMSO) solution, DMSO 'opens up' the intramolecular hydrogen bonding and forms solute-solvent intermolecular hydrogen bonded C343-DMSO complex. Analysis of frontier molecular orbitals reveals that intramolecular charge transfer (ICT) occurs in the first excited state both for C343 monomer and complex. The results of optimized geometric structures indicate that the intramolecular hydrogen bonding interaction is strengthened while the intermolecular hydrogen bonding is weakened in excited state, which is confirmed again by monitoring the shifts of characteristic peaks of infrared spectra. We demonstrated that DMSO solvent can not only break the intramolecular hydrogen bonding to form intermolecular hydrogen bonding with C343 but also alter the mechanism of excited state hydrogen bonding strengthening. 20. Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2 KAUST Repository Nazir, Safdar 2011-01-31 Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8518101572990417, "perplexity": 4638.066521374741}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-39/segments/1537267156460.64/warc/CC-MAIN-20180920101233-20180920121633-00470.warc.gz"}
https://www.zora.uzh.ch/id/eprint/28847/	# Growth-dependent phenotypic variation of molluscan shells: implications for allometric data interpretation Urdy, S; Goudemand, N; Bucher, H; Chirat, R (2010). Growth-dependent phenotypic variation of molluscan shells: implications for allometric data interpretation. Journal of Experimental Zoology. Part B: Molecular and Developmental Evolution:303-326. ## Abstract In recent years, developmental plasticity has received increasing attention. Specifically, some studies highlighted a possible association between shell shape and growth rates in intertidal gastropods. We use a growth vector model to study how hypothetical growth processes could underlie developmental plasticity in molluscs. It illustrates that variation in instantaneous shell growth rate can induce variability in allometric curves. Consequently, morphological variation is time-dependent. Basing our model parameters on a study documenting the results of transplants experiments of three gastropods ecomorphs, we reproduce the main aspects of the variation in size, shape, and growth rates among populations when bred in their own habitat or transplanted to another ecotype habitat. In agreement with empirical results, our simulation shows that a flatter growth profile corresponds to conditions of rapid growth. The model also allows the comparison of allometric slopes using different subdata sets that correspond to static and ontogenetic allometry. Our model highlights that depending on subdata sets, the main effects could be attributed to source population or environment. In addition, convergence or divergence of allometric slopes is observed depending on the subdata sets. Although there is evidence that shell shape in gastropods is to some extent growth rate dependent, gaining a general overview of the issue is challenging, in particular because of the scarcity of studies referring to allometry. We argue that the dynamics of development at the phenotypic level constitute a non-reducible level of investigation if one seeks to relate the observed amount of phenotypic variation to variability in the underlying factors. ## Abstract In recent years, developmental plasticity has received increasing attention. Specifically, some studies highlighted a possible association between shell shape and growth rates in intertidal gastropods. We use a growth vector model to study how hypothetical growth processes could underlie developmental plasticity in molluscs. It illustrates that variation in instantaneous shell growth rate can induce variability in allometric curves. Consequently, morphological variation is time-dependent. Basing our model parameters on a study documenting the results of transplants experiments of three gastropods ecomorphs, we reproduce the main aspects of the variation in size, shape, and growth rates among populations when bred in their own habitat or transplanted to another ecotype habitat. In agreement with empirical results, our simulation shows that a flatter growth profile corresponds to conditions of rapid growth. The model also allows the comparison of allometric slopes using different subdata sets that correspond to static and ontogenetic allometry. Our model highlights that depending on subdata sets, the main effects could be attributed to source population or environment. In addition, convergence or divergence of allometric slopes is observed depending on the subdata sets. Although there is evidence that shell shape in gastropods is to some extent growth rate dependent, gaining a general overview of the issue is challenging, in particular because of the scarcity of studies referring to allometry. We argue that the dynamics of development at the phenotypic level constitute a non-reducible level of investigation if one seeks to relate the observed amount of phenotypic variation to variability in the underlying factors. ## Statistics ### Citations Dimensions.ai Metrics 37 citations in Web of Science® 30 citations in Scopus®	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8780739903450012, "perplexity": 3585.0930187671684}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039742253.21/warc/CC-MAIN-20181114170648-20181114192648-00409.warc.gz"}
http://mathhelpforum.com/differential-geometry/191451-analytic-function-unit-disk.html	# Math Help - Analytic Function in the Unit Disk 1. ## Analytic Function in the Unit Disk Dear Colleagues, Let $f$ be analytic function in the unit disk $D=\{z \in C:\|z\|<1\}$ with $\|f(z)\|<1$, for any $z \in D$. If $f(z_{1})=z_{1}, f(z_{2})=z_{2}$ where $z_{1}$ and $z_{2}$ are distinct, show that $f(z)=z$ for any $z \in D$.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 9, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9863070249557495, "perplexity": 140.67365275755702}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1433195035761.14/warc/CC-MAIN-20150601214355-00062-ip-10-180-206-219.ec2.internal.warc.gz"}
https://www.intmath.com/blog/learning/nuvvo-learning-management-system-212	# Nuvvo learning management system By Murray Bourne, 19 Jan 2006 Nuvvo used to be a paid service but has recently become a free offering. Update (Dec 2013): Seems Nuvvo no longer exists. You can create e-learning courses and enroll students (Nuvvo takes 8% of the course fee - fair enough, probably, since they host and support the service). Things I like better than Blackboard (the LMS that I know best): • Each item (like content, quizzes, etc) has a "blog" at the bottom of the page where students can discuss the item. This is better than going elsewhere in the learning management system to find a discussion relevant to that topic or item. • Clean look and feel Things I don't like: • It's surprisingly tricky to navigate. Links are not always obvious (they look like headings or vice-versa) and colours used add to this confusion (I watched as a colleague tried to navigate - he had similar problems) • It feels like the model used is the "tell-em, test-em" model of e-learning (it includes T/F, multiple choice and short essay quizzes). But because of the blog on each page, this could be overcome. Overall, an interesting concept. I may use it for Interactive Mathematics down the track. Be the first to comment below. ### Comment Preview HTML: You can use simple tags like <b>, <a href="...">, etc. To enter math, you can can either: 1. Use simple calculator-like input in the following format (surround your math in backticks, or qq on tablet or phone): a^2 = sqrt(b^2 + c^2) (See more on ASCIIMath syntax); or 2. Use simple LaTeX in the following format. Surround your math with $$ and $$. $$\int g dx = \sqrt{\frac{a}{b}}$$ (This is standard simple LaTeX.) NOTE: You can't mix both types of math entry in your comment.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6562829613685608, "perplexity": 5378.236723437907}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-43/segments/1508187820556.7/warc/CC-MAIN-20171017013608-20171017033608-00293.warc.gz"}
https://www.physicsforums.com/threads/derivatives-and-sa.5745/	# Derivatives and SA • Start date • #1 Gale 676 2 in my calc class, someone noticed that when you take the derivative of the formula for volume of a circle, it becomes the formula for the surface area. anyone know why? and what other shapes is this also true for? • #2 Staff Emeritus Gold Member 10,275 40 It's because the volume of a sphere can be found by integrating the surface area of spherical shells from the center to the surface. Integrate[4 Pi r^2, {r, 0, R}] = 4/3 Pi R^3 It works for any shape. An area integrated over a third dimension is a volume. For a cube, the integral looks like: Integrate[6 Sqrt[2] s^2, {s, 0, (Sqrt[2]/2) R}] = R^3 - Warren • #3 Homework Helper 43,021 970 It is also true that the derivative of the Area of a circle: [pi]r2 (with respect to r) is the circumference (2[pi]r). That's basically because, as Chroot said, that you can find the volume a sphere by integrating the surface area of "nested" spheres or the area of a circle by integrating the circumference of "nested" circles. • #4 Gale 676 2 damn well, too bad i don't know what integrating is... i'm not that far into calc, but i guess i can tell my teacher that at any rate. also, what other shapes, aside from circles. i think he said something about cones... or conics... or something, i missed it. • #5 Staff Emeritus Gold Member 14,967 19 Any surface that, when applying a coating of paint with uniform thickness, is (sufficiently close to) the same kind of surface. • #6 Gale 676 2 Any surface that, when applying a coating of paint with uniform thickness, is (sufficiently close to) the same kind of surface. umm... i have no clue what that means... and since we're on the subject of my having no clue... what is this 'nesting of spherical shells' • #7 Staff Emeritus Gold Member Dearly Missed 6,881 10 Like layers of an onion. There is an outside sphere, just a thin shell, and inside that is another shell whose outside surface exactly coincides with the inside surface of the first one. And ... so on... one shell inside another till you get to the center. These shells all have the same finite thickness. And then you think of having twices as many shells, each half as thick. And ... so on ... till in the limit of the thickness going to zero you recover the volume of the solid ball . • #8 lethe 653 0 this result also follows from stoke s theorem, one of my favorite theorems. • #9 893 3 Originally posted by Gale17 umm... i have no clue what that means... and since we're on the subject of my having no clue... what is this 'nesting of spherical shells' Here's the connection: If you paint a sphere, then the volume of paint used is the surface area times the thickness of the paint layer. Or, another way to put it is that the surface area is the volume of paint (dV) divided by the thickness of paint (dr); S=dV/dr. This works because for a sphere, the thickness of paint is an increment in radius. It wouldn't work for, say, a cube when its volume is epressed in terms of the length of a side: V=a^3, but S is not 3a^2. However, if you write the volume of a cube in terms of _half_ a side's length h=a/2, then V=8h^3 and S is indeed 24h^2. • #10 phoenixthoth 1,605 2 "Like layers of an onion. There is an outside sphere, just a thin shell, and inside that is another shell whose outside surface exactly coincides with the inside surface of the first one. And ... so on... one shell inside another till you get to the center. These shells all have the same finite thickness. And then you think of having twices as many shells, each half as thick. And ... so on ... till in the limit of the thickness going to zero you recover the volume of the solid ball ." these layers have infinitesimal thickness, right? cheers, phoenix • #11 Staff Emeritus Gold Member 14,967 19 An example of something with which this will not work is in order... ellipses and other conic sections are good example; if you paint an ellipse (with an even thickness), the result is not an ellipse. • #12 137 0 Damn you all, thats all I can ever think about when I'm painting! • #13 Gale 676 2 thanks, i understand now i think. i'll double check in class tomorrow. whats is stokes theorem? • #14 Gale 676 2 ok, i didn't understand your answers well enough to explain to my teacher, who by the way, is a wicked pain in the ass, and won't just tell me. so, could some one either explain this a different way or tell me where i could find out or something. also: i just realized i worded my first question wrong, i said circle, i meant sphere. when you take the derative from the formula for the volume of a shere, you get the formula for it's surface area. i need to know why this is, and what shapes it holds true for, and also why? • #15 Staff Emeritus Gold Member 10,275 40 Since a circle doesn't have a volume, I automatically assumed you actually meant sphere. All our responses are appropriate to the sphere. Did you not read the responses? Or did you just not understand them? Let's say you start with a tiny little ball bearing -- one so small that its volume is negligible. You then paint a very thin layer of paint around the ball bearing. Then you add another layer, and another layer, and so on, until you have a baseball sized sphere. The volume is made up of many layered spherical shells of paint. You can imagine that the thickness of each of the layers is so small that they are essentially two-dimensional surfaces. The volume of the sphere can be easily imagined to be composed of an infinite number of infinitely thin layers of paint. The surface area of each layer is 4 pi r^2. The integral (sum) of the layers is a volume, 4/3 pi R^3. (r is an internal radius, R is the radius of the outermost surface.) If the integral of 4 pi r^2 (dr) from 0 to R (from the center to the outside of the sphere) is 4/3 pi R^3, then the converse is also true: the derivative of 4/3 pi R^3 is 4 pi r^2. As has been mentioned, this method works for any volumes that can be built out of such layers of paint. - Warren • #16 Gale 676 2 ah thanks, i was only sort of half understanding your answers. i read them, and understood what they said, but not how they related to the math i guess. would you believe that the little peice of understanding i kept missing was that the "layers of paint" were '2 dimensional' or individual sort of surface areas. i get it now though, i was just dense. • #17 lethe 653 0 Originally posted by Gale17 whats is stokes theorem? stokes theorem says that for any space, of any dimension, the integral of some object on the boundary of that object equals the integral of the derivative of that object. this breaks down into many familiar special cases, the fundamental theorem of calculus, the divergence theorem, the curl theorem for line integrals, the gradient theorem, and many higher dimensional generalizations. the boundary of a filled ball is the sphere, so stokes theorem makes this relationship trivial to prove, along with many generalizations of it. • Last Post Replies 1 Views 442 • Last Post Replies 2 Views 899 • Last Post Replies 0 Views 290 • Last Post Replies 3 Views 431 • Last Post Replies 4 Views 278 • Last Post Replies 3 Views 901 • Last Post Replies 6 Views 541 • Last Post Replies 1 Views 259 • Last Post Replies 2 Views 317 • Last Post Replies 4 Views 308	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8585806488990784, "perplexity": 803.5409667648249}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030337428.0/warc/CC-MAIN-20221003164901-20221003194901-00371.warc.gz"}
http://www.ck12.org/geometry/Surface-Area-and-Volume-of-Solids/lesson/Surface-Area-and-Nets/r13/	<meta http-equiv="refresh" content="1; url=/nojavascript/"> You are viewing an older version of this Concept. Go to the latest version. # Surface Area and Volume of Solids ## Sum of the area of the faces of a solid and drawings that show the edges and faces in 2-D. % Progress Progress % Surface Area and Nets A cup of paint covers about 22 square feet. You need to paint all faces of a cube to use as a prop in a play. Each edge of the cube is 2.5 feet long. How much paint will you need to buy? #### Watch This http://www.youtube.com/watch?v=ERlkBTxlVMQ Brightstorm: Surface Area of Pyramids #### Guidance A net is a drawing that shows the edges and faces of a solid in two dimensions. You can think of a net as what you would get if you “unfolded” a solid. In the series of images below, you can see a triangular prism, the triangular prism starting to be unfolded, and the net for the triangular prism. The surface area of a solid is the sum of the area of all its faces. This means that one way to find the surface area of a solid is to find the area of its net. Example A Find the approximate surface area of the triangular prism below. The base is an equilateral triangle. Solution: The net is made of three congruent rectangles and two congruent equilateral triangles. The surface area is the sum of the areas of the five shapes. To find the area of the triangle, you need to know the height of the triangle. Using the Pythagorean Theorem, you can determine that the height is approximately 3.46 inches. $Area_{Triangle} &=\frac{bh}{2}=\frac{4\cdot 3.46}{2}=6.93 \ in^2 \\Area_{Rectangle} &=bh=4 \cdot 6=24 \ in^2 \\Total \ Surface \ Area &=2(6.93)+3(24)=85.86 \ in^2$ Example B Draw the net of a square pyramid. Solution: Example C A square pyramid has a height of 20 inches. Each side of the square base is 12 inches. What is the surface area of the pyramid? Solution: In order to find the surface area, you will need to determine the area of the triangle faces. In order to find the area of each triangle face, you will need the base and height of the triangle. In order to do this, imagine a right triangle standing upright in the pyramid. The height of this triangle is 20 inches and the base of the triangle is 6 inches. It's hypotenuse, which is the height of the triangle face, can be determined with the Pythagorean Theorem. $6^2+20^2=c^2\rightarrow c\approx 20.88 \ in$ Now you can find the area of each of the five shapes that make up the net in order to find the surface area. $Area_{Triangle} &=\frac{bh}{2}=\frac{(12\cdot 20.88)}{2}=125.28 \ in^2 \\Area_{Square} &=12^2=144 \ in^2\\Total \ Surface \ Area &=4(125.28)+144=645.12 \ in^2$ Concept Problem Revisited One cup of paint covers about 22 square feet. Each edge of the cube is 2.5 feet long. In order to figure out how much paint you will need, you should find the surface area of the cube. The cube has six congruent square faces. The area of each square is $(2.5)^2=6.25 \ ft^2$ . The total surface area of the cube is $37.5 \ ft^2$ . You will need $\frac{37.5}{22}\approx 1.7$ cups of paint. #### Vocabulary A net is a drawing that shows the edges and faces of a solid in two dimensions. The surface area of a solid is the sum of the area of all its faces. #### Guided Practice 1. Draw the net for a pentagonal prism. 2. The base of a pentagonal prism is the following pentagon: Find the area of the pentagon by dissecting the pentagon into five triangles and finding the area of each triangle. 3. Find the surface area for a pentagonal prism with a height of 25 inches and a base as described in #2. 1. 2. Use the Pythagorean Theorem to find the height of each triangle. $5^2+b^2=8.5^2\rightarrow b \approx 6.87$ The area of each triangle is approximately $\frac{bh}{2}=\frac{10 \cdot 6.87}{2}=34.37 \ in^2$ . Therefore, the area of the pentagon is $34.37 \cdot 5=171.85 \ in^2$ . 3. The pentagonal prism is made of five rectangular faces and two pentagonal faces. Each rectangle is 10 inches by 25 inches. $Area_{Pentagon} &=171.85 \ in^2 \\Area_{Rectangle} &=(10 \cdot 25)=250 \ in^2\\Total \ Surface \ Area &=2(171.85)+5(250)=1593.69 \ in^2$ #### Practice 1. Explain the connection between the surface area of a solid and the net of a solid. 2. When stating a surface area, why do you use square units such as “ $in^2$ ”? A triangular pyramid has four congruent equilateral triangle faces. Each edge of the pyramid is 6 inches. 3. Draw a net for the pyramid. 4. Find the area of one triangle face. 5. Find the surface area of the pyramid. A 20 inch tall hexagonal pyramid has a regular hexagon base that can be divided into six equilateral triangles with side lengths of 12 inches, as shown below. 6. Draw a net for the pyramid. 7. Find the area of the hexagon base. 8. The pyramid has 6 triangular faces. Use the Pythagorean Theorem to help you to find the height of each of these triangles. 9. Find the total surface area of the pyramid. A square prism is topped with a square pyramid to create the composite solid below. 10. Draw a net for the solid. 11. There are four triangular faces. Use the Pythagorean Theorem to help you find the height of each of these triangles. 12. Find the total surface area of the solid. A solid has the following net. 13. What type of solid is this? 14. Find the surface area of the solid. 15. What would the net of a cylinder look like? Try to make a sketch. 16. What would the net of a cone look like? Try to make a sketch. ### Vocabulary Language: English Net Net A net is a diagram that shows a “flattened” view of a solid. In a net, each face and base is shown with all of its dimensions. A net can also serve as a pattern to build a three-dimensional solid. Surface Area Surface Area Surface area is the total area of all of the surfaces of a three-dimensional object.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 11, "texerror": 0, "math_score": 0.6192737221717834, "perplexity": 277.5154633015592}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375095557.73/warc/CC-MAIN-20150627031815-00050-ip-10-179-60-89.ec2.internal.warc.gz"}
http://libros.duhnnae.com/2017/jul7/150090974054-One-dimensional-model-of-streaking-experiment-in-solids-Condensed-Matter-Other-Condensed-Matter.php	# One-dimensional model of streaking experiment in solids - Condensed Matter > Other Condensed Matter One-dimensional model of streaking experiment in solids - Condensed Matter > Other Condensed Matter - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online. Abstract: One-dimensional model for study of sub-femtosecond experiment with metalsurface is put forward. The important features of the system, such as thepseudopotential for electron motion in the metal bulk, abrupt decrease of thenormal to the surface external electromagnetic field in the bulk, finite valueof the mean free path for electrons in the metal, and action on the ejectedelectron by the stationary screened positive hole in the metal are includedin the model. The results obtained reveal dependence of the streaking effect onthe final energy of the ejected electron. Meanwhile, the dependence of thestreaking on the character of the initial state localized or delocalizedappears to be more pronounced. This result may provide an additional mechanismfor interpretation of the results of very recent experiment Cavalieri\emph{et.al}, NATURE \textbf{449} 1029-1032 2007 . Autor: A.K. Kazansky, P.M. Echenique Fuente: https://arxiv.org/	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9191958904266357, "perplexity": 4189.988620351601}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039741016.16/warc/CC-MAIN-20181112172845-20181112194845-00145.warc.gz"}
https://math.stackexchange.com/questions/680647/expanding-1-s21s1-into-partial-fractions-by-brute-force	# Expanding $1/[(s^2+1)(s+1)]$ into partial fractions by brute force I want to do partial fractions on: $1/[(s^2+1)(s+1)]$ $(as+b)/(s^2+1) + c/(s+1)$ Multiplying both sides by $(s^2+1)(s+1)$, get $a=-1/2, b=1/2, c=1/2$ $(-s/2+1/2)/(s^2+1) + (1/2)/(s+1) = 1/[(s^2+1)(s+1)]$ Unfortunately when I add $(-s/2+1/2)/(s^2+1) + (1/2)/(s+1)$ I get $(1/4)/[(s^2+1)(s+1)]$. Where did I go wrong? • Can you explain how you did your last step of "when I add"? – Calvin Lin Feb 18 '14 at 9:34 • [(-s/2+1/2)(s+1)+(1/2)(s^2+1)]/[(s^2+1)(s+1)] – user122415 Feb 18 '14 at 9:43 • Yes, and I'd ask you to justify that expansion. For example, expand the numerator : $( - \frac{s}{2} + \frac{1}{2} ) ( s+1) + \frac{1}{2} (s^2 + 1)$. What do you get? – Calvin Lin Feb 18 '14 at 9:47 • -s^2/2-s/2+s/2+1/2+s^2/2+1/2 = 1/4 – user122415 Feb 18 '14 at 9:51 • Please triple check. For example, when you substitute in $s=0$, what do you get? – Calvin Lin Feb 18 '14 at 9:53 No,when you add $$\frac{-s/2+1/2}{s^2+1} + \frac{1/2}{s+1}$$ you get $$\frac{1}{2}\frac{1-s^2+1}{(s^2+1)(s+1)}$$ or $$\frac{1}{(s+1)(s^2+1)}.$$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7039035558700562, "perplexity": 935.4645096913521}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-30/segments/1563195528141.87/warc/CC-MAIN-20190722154408-20190722180408-00202.warc.gz"}
http://mathoverflow.net/questions/115803/the-pde-u-t-u-xx-u-yy-the-simplest-linear-second-order-pde-that-isnt-ell	# The PDE $u_t=u_{xx}-u_{yy}$: The simplest linear second-order PDE that isn't elliptic, parabolic, or hyperbolic. I know that there have been several questions on here and stackexchange about linear PDE's which don't fall into the standard classification, but I had a more focused question which I haven't seen answered. The PDE $u_t=u_{xx}-u_{yy}$ (or, equivalently, $u_t=u_{xy}$), is the simplest linear second-order PDE that is not elliptic, parabolic, or hyperbolic. Its time-invariant solutions are solutions to the one-dimensional wave equation. My question is, How does this PDE compare to the standard parabolic and hyperbolic PDE's in the following categories: • Fundamental solution: is there an integral solution which is a convolution with a fundamental solution? • Smoothness: are solutions infinitely smooth or does the smoothness depend on boundary conditions? • Propagation speed: infinite or finite? I only recently read Evan's PDE book, and the only question I really took a crack at was the first. I looked for a solution involving exponentials in t, but I couldn't find one. I am interested in this question purely from a classification standpoint. Thanks! Edit: As the comments below indicate, there can be no general solution with arbitrary initial conditions analogous to that for parabolic or hyperbolic equations. Also, solutions need not be infinitely smooth. Since this answer was pieced together from the comments, I'm making this community wiki, in case anyone would like to add to it later. - I don't know if this particular equation has been studied before, but there was a lot of work on linear constant coefficient PDE's, notably by Leon Ehrenpreis, back in the 60's and maybe 70's. You might want to dig through those to see what was done back then. Also, the most obvious way to try to analyze your questions is via separation of variables. – Deane Yang Dec 8 '12 at 16:34 If one specialises to solutions independent of x, one obtains the backwards heat equations $u_t = -u_{yy}$, which has basically no good solvability properties forward in time. So I doubt that there is any meaningful way to solve the initial value problem. – Terry Tao Dec 8 '12 at 17:54 Solutions need not be infinitely smooth. A nonsmooth solution $u(x,y)$ to the equation $u_{xx}-u_{yy}=0$ (and these certainly exist) will be a solution to your equation. – Robert Bryant Dec 8 '12 at 19:46 As the comments by Terry Tao and Robert Bryant indicate, the understanding of a broad class of solutions to a PDE usually requires both identifying what boundary or initial value conditions to impose and in what function space to look for solutions. Standard PDE's come from physical models or variational problems that tell you what these should be. With a PDE that is not based on any such model or variational problem, it is much less clear what to do. – Deane Yang Dec 8 '12 at 20:44 Exponential solutions are easy to find. Just plug $\exp(ax+by+ct)$, and you will see that every $(a,b,c)$ that satisfies $c=a^2-b^2$ gives you a solution. This polynomial is called the symbol of the differential operator. For the general theory of linear PDE with constant coefficients, the best source is the first two volumes of Hormander, Analysis of Linear Differential Operators.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9044260382652283, "perplexity": 287.2629748820031}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-22/segments/1464049274324.89/warc/CC-MAIN-20160524002114-00078-ip-10-185-217-139.ec2.internal.warc.gz"}
https://quantnet.com/threads/north-carolina-state-university-financial-mathematics-program.10054/	# North Carolina State University Financial Mathematics program #### onthesc very nice article! I really enjoyed reading the thoughts you've shared here. Last edited by a moderator: Thank you. #### Ryan I attended NCSU's MFM and think this is a good evaluation. As mentioned, biggest plus is the cost, especially for in-state students. I paid one semester what one class costs in a private school. One drawback is the program is taught by academic mathematicians/statisticians so some coursework may be very theoretical (e.g. graduate course in probability or math stat) and only certain classes apply directly to finance. Not necessarily a bad thing as degree is somewhat of a hybrid of financial math and applied math master but it's good to know what you're getting into. Another point I'd add that is typically underrated is that there is a growing relationship with the program/NCSU in general and triangle tech companies (the new NCSU Math/Stat building is called SAS Hall for a reason--founder of SAS was a NCSU Stat PhD student) and Charlotte banks (i.e. Bank of America--BofA gave $1MM to start an Enterprise Risk Initiative in the school of Management/Business at NCSU). #### clarkchao Hi I want to know some specific details in your comment that "Another point I'd add that is typically underrated is that there is a growing ..." you mean the students will have more chances to reach industry? #### elaine Pretty good one! I have been searching for useful info about NCSU FM for a while. Thanks! #### mazart Hi, I am a new one admitted in the NCSU finmath. Does anyone have much more details about this program? Such as career service, industry connection and resources for international students. Thanks! #### mazart I attended NCSU's MFM and think this is a good evaluation. As mentioned, biggest plus is the cost, especially for in-state students. I paid one semester what one class costs in a private school. One drawback is the program is taught by academic mathematicians/statisticians so some coursework may be very theoretical (e.g. graduate course in probability or math stat) and only certain classes apply directly to finance. Not necessarily a bad thing as degree is somewhat of a hybrid of financial math and applied math master but it's good to know what you're getting into. Another point I'd add that is typically underrated is that there is a growing relationship with the program/NCSU in general and triangle tech companies (the new NCSU Math/Stat building is called SAS Hall for a reason--founder of SAS was a NCSU Stat PhD student) and Charlotte banks (i.e. Bank of America--BofA gave$1MM to start an Enterprise Risk Initiative in the school of Management/Business at NCSU). I attended NCSU's MFM and think this is a good evaluation. As mentioned, biggest plus is the cost, especially for in-state students. I paid one semester what one class costs in a private school. One drawback is the program is taught by academic mathematicians/statisticians so some coursework may be very theoretical (e.g. graduate course in probability or math stat) and only certain classes apply directly to finance. Not necessarily a bad thing as degree is somewhat of a hybrid of financial math and applied math master but it's good to know what you're getting into. Another point I'd add that is typically underrated is that there is a growing relationship with the program/NCSU in general and triangle tech companies (the new NCSU Math/Stat building is called SAS Hall for a reason--founder of SAS was a NCSU Stat PhD student) and Charlotte banks (i.e. Bank of America--BofA gave \$1MM to start an Enterprise Risk Initiative in the school of Management/Business at NCSU). Hi Ryan, Replies 4 Views 1K Replies 8 Views 2K Replies 11 Views 3K • Poll Replies 3 Views 294 Replies 15 Views 1K	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.261337012052536, "perplexity": 3933.3176461634694}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243988986.98/warc/CC-MAIN-20210509122756-20210509152756-00357.warc.gz"}
https://www.physicsforums.com/threads/circular-launch.42552/	# Circular Launch 1. Sep 10, 2004 ### EaGlE A ball is launched up a semicircular chute in such a way that at the top of the chute, just before it goes into free fall, the ball has a centripetal acceleration of magnitude 2g. 1.)How far from the bottom of the chute does the ball land? Your answer for the distance the ball travels from the end of the chute should contain R. D=__________ can someone help me start this? i really dont know where to start this problem from. #### Attached Files: • ###### M2K.ca.7.jpg File size: 6.3 KB Views: 74 2. Sep 10, 2004 ### Sirus Use what you know to find the velocity of the ball at the top of the chute, then treat it as a projectiles question, where you know the initial velocity, the initial height (2R), and the acceleration due to gravity: how much time does it take for the ball to reach the ground when considering only its accelerated vertical motion, and how far will it have travelled horizontally during this time? 3. Sep 10, 2004 ### Pyrrhus Remember: $$A_{c} = \frac{V^2}{R}$$ where $$A_{c}$$ is Centripetal Acceleration. 4. Sep 10, 2004 ### EaGlE i dont remeber us doing this in class at all, so i read the chapter relating to this subject many times, and it's confusing for me. ok i know that a = 9.8m/s^2, initial velocity = 0, initial height = 2r so... x(t) = 2r + 0 + 1/2(-9.8)t^2 2r = -4.9t^2 sorry but i have no clue on what to do... $$A_{c} = \frac{V^2}{R}$$ we dont know velocity right? ..... 5. Sep 11, 2004 ### Pyrrhus Well the Problem gives you the $$A_{c}$$ and in the graphic you can see the radius is R, how can you use the equation i gave you, in order to find the speed at the top? and then use that speed for the projectile motion part. Similar Discussions: Circular Launch	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.897546648979187, "perplexity": 647.3964604223063}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-22/segments/1495463608765.79/warc/CC-MAIN-20170527021224-20170527041224-00152.warc.gz"}
http://mathhelpforum.com/pre-calculus/147684-solve-non-linear-system-equations.html	# Math Help - solve - Non-linear System of equations 1. ## solve - Non-linear System of equations solve 2. Originally Posted by dapore solve From equation 1: $x^3 = 3xy^2 + 11$ $x^3 - 11 = 3xy^2$ $\frac{x^3 - 11}{3x} = y^2$ $y = \sqrt{\frac{x^3 - 11}{3x}}$. Substituting into equation 2: $y^3 = 3x^2y + 2$ $\left(\sqrt{\frac{x^3 - 11}{3x}}\right)^3 = 3x^2\sqrt{\frac{x^3 - 11}{3x}} + 2$ Now try to solve for $x$. 3. $(1) + i(2)$ and $(1) - i(2)$ we have $(x-iy)^3 = 11+2i ~~ (x+iy)^3 = 11-2i$ $x-iy = \sqrt[3]{11+2i} ~~ x+iy = \sqrt[3]{11-2i}$ $x = Re(\sqrt[3]{11+2i}) ~~ , ~~ y = - Im(\sqrt[3]{11+2i})$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 12, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9625028371810913, "perplexity": 3961.388246778887}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-41/segments/1410657124771.92/warc/CC-MAIN-20140914011204-00293-ip-10-196-40-205.us-west-1.compute.internal.warc.gz"}
https://kb.osu.edu/handle/1811/16511?show=full	dc.creator Johns, J. W. C. en_US dc.creator McKellar, A. R. W. en_US dc.creator Oka, T. en_US dc.creator Romheld, M. en_US dc.creator Trombetti, A. en_US dc.date.accessioned 2006-06-15T17:17:00Z dc.date.available 2006-06-15T17:17:00Z dc.date.issued 1974 en_US dc.identifier 1974-WE-4 en_US dc.identifier.uri http://hdl.handle.net/1811/16511 dc.description $^{1}$T. W. H\""ansch, I. S. Shahin, and A. L. Schawlow, Phys. Rev. Letters 27, 707 (1971). $^{2}$S. M. Freund, J.W.C. Johns, A.R.W. McKellar, and T. Oka, J. Chem. Phys. 59, 3445 (1973). en_US dc.description Author Institution: Division of Physics, National Research Council of Canada en_US dc.description.abstract While observing laser Stark Lamb dips for vibration-rotation transitions which are nearly coincident with infrared laser lines, we have observed extra dips midway between the dips associated with successive M components. These extra dips have been observed for a transition in the $2\nu_{2}$ overtone band of $NH_{3}$ In the 5$\mu$ region using a CO laser and for five transitions in the $\nu_{3}$ fundamental bands of $CH_{3}F$ and $^{13}CH_{3}F$ in the 10$\mu$ region using a $CO_{2}$ laser. They are similar to those observed by H\”ansch, Shahin and $Schawlow^{1}$ in that they appear midway between normal Lamb dips and that they are due to molecules with a non zero velocity component along the direction of the laser beam. However, in our experiments, the Stark shifted energy levels constitute a four level system and the saturating transition does not affect the other transition directly. We believe that the extra dips observed in such a system are caused by efficient collision induced transitions between different M components, without change of $velocity.^{2}$ en_US dc.format.extent 484458 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title OBSERVATION OF COLLISION-INDUCED CENTER DIPS IN LAMB DIP STARK SPECTROSCOPY en_US dc.type article en_US	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8848551511764526, "perplexity": 8182.070848787592}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141706569.64/warc/CC-MAIN-20201202083021-20201202113021-00418.warc.gz"}
http://math.stackexchange.com/questions/3388/pq%c2%b2-rsp-where-p-q-r-s-are-distinct-single-digit-natural-numbers-then-r	# (PQ)²=RSP, where P,Q,R,S are distinct single digit natural numbers, then R=? I have a problem I tried to solve, but couldn't because I don't know the method to solve it and I've never come across such problem. Here's the problem. $(PQ)²=RSP$ Where $P, Q, R, S$ are distinct single digit natural numbers, then $R=$? We need to find out the value of $R$, and given option are a) $1$ b) $2$ c) $3$ d) $4$ e) $5$ I've tried solving it by option with newly created equation as $Q^2=\frac{RS}{P}$ and taking values of $R$ from above options and other variables as distinct single digit numbers other than $R$, I've gone to a level after which I've got myself a lot confused and didn't know what to do. I think there is easier method to solve it which I don't know. I'd appreciate if someone could give me a hand with this. Thanks in advance. :) PS: The answer is c) $3$ - Do PQ and RSP indicate concatenation? You should say this. – Qiaochu Yuan Aug 26 '10 at 16:37 I'm not sure. They haven't given any more information about it. But I'm presuming they mean multiplication. Like this - (PQ)²=RS*P I could be wrong though. :\ – Electrifyings Aug 26 '10 at 16:42 Oh. You don't seem to have realized this! PQ does not mean P times Q, it means the number with first digit P and second digit Q. – Qiaochu Yuan Aug 26 '10 at 16:43 Qiaochu: You're right, but it can be seen why he'd think multiplication is happening; joining two variables as concatenation is something you don't see very frequently. – Ｊ. Ｍ. Aug 26 '10 at 16:47 Retagged from "numerical-methods" (which this definitely isn't) to "arithmetic." – whuber Aug 26 '10 at 18:30 The steps are as follows. • A square number can only end in $1, 4, 5, 6, 9$. To prove this one uses modular arithmetic. So $P = 1, 4, 5, 6, 9$. • $40^2 > 999$, so $P = 1$. • Since $(PQ)^2$ ends in $1$, it follows that $Q = 1, 9$. • Since $P \neq Q$, it follows that $Q = 9$. • So the digits are $19^2 = 361$. - OMG, thanks for clearing this up. Yeah, I figured this by trial and error and by going with options. LOL, all this time I was thinking its a multiplication and never had a single strike in my mind about concatenation. Thanks man for clearing it up! You made my day! :D – Electrifyings Aug 26 '10 at 16:50 Generalizing from decimal to arbitrary radix, a quick computer search seems to indicate that there are only a handful of radices with such a unique solution. This leads to a proof of the following THEOREM $\;$ If in radix $\rm M$ notation we have $\rm (PQ)^2 = RSP$ with $\rm P,Q,R,S$ distinct digits and this solution is unique in radix $\:\rm M \:$ then it is one of the following, where $\;\rm A = 10,\; B = 11, \:\ldots,\: I = 18 \;$. $$\begin{array}{\|r\|r\|r\|} \hline \rm M & \rm PQ & \rm RSP \\ \hline 6 & 15 & 321 \\ 7 & 23 & 562 \\ 8 & 17 & 341 \\ 9 & 18 & 351 \\ 10 & 19 & 361 \\ 11 & \rm 1A & 371 \\ 18 & \rm 1H & \rm 3E1 \\ 19 & \rm 1\:I & \rm 3F1 \\ \end{array}$$ Proof: $\;$ The two general solutions listed below prove that all radices $\;\rm M > 26 \;$ have nonunique solution (except possibly $\rm M = 44\:$). The remaining small number of exceptional cases were verified by computer. $\quad\quad\rm (1\: M + M-1)^2 \;=\; \;\;\: 3\: M^2 + (M\;-\;\:4) M + 1, \quad\quad M > 7$ $\quad\quad\rm (4\: M + M-2)^2 \;=\; 24\: M^2 + (M-20) M + 4, \quad\quad M>26,\;\; M \ne 44$ - Nice conjecture. But when M > 81 you can check that 93^2 = (9M+3)^2 = 81M^2 + 54M + 9 = (81)(54)9; i.e., (M,P,Q,R,S) = (M,9,3,81,54) is a solution for all M >= 82. – whuber Aug 27 '10 at 20:50 @whuber: The conjecture is true - see the above proof. – Bill Dubuque Jan 12 '11 at 23:38	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9232916235923767, "perplexity": 517.244489902126}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802766267.61/warc/CC-MAIN-20141217075246-00092-ip-10-231-17-201.ec2.internal.warc.gz"}
http://math.stackexchange.com/questions/186307/hopf-algebra-identity-under-convolution	# Hopf algebra: Identity under convolution In Hopf algebra texts, it is usually stated that $1=\eta\epsilon\in$Hom($H^C,H^A$) is the identity under convolution. $\eta$ is the unit, $\epsilon$ is the counit. My question is, is that a definition, or can it be proved? Sincere thanks for any help. (Do let me know if you need any clarification on the above notations.) - Let $\mathbb K$ be a field. Let $(A,m)$ be a associative $\mathbb K$-algebra with unit $\eta: \mathbb K \to A$ and let $(C,\Delta)$ be a coassociative $\mathbb K$-coalgebra with counit $\varepsilon: C \to \mathbb K$. The convolution $\star: \operatorname{Hom}(C,A) \times \operatorname{Hom}(C,A) \to \operatorname{Hom}(C,A)$ is defined by $$f \star g := m \circ (f \otimes g) \circ \Delta.$$ Let $\mathbf 1 := \eta(1_{\mathbb K})$, then from the definition of the unit follows $$m(\mathbf 1 \otimes a) = a \quad \text{for all } a\in A.$$ Furthermore, $$(\varepsilon \otimes \operatorname{id}) \circ \Delta = 1_{\mathbb K} \otimes \operatorname{id},$$ by definition of counit. Using this we show $$\eta \varepsilon \star f = f \star \eta\varepsilon = f \quad \text{for all } f \in\operatorname{Hom}(C,A).$$ For all $c \in C$ we have \begin{align} (\eta\varepsilon \star f)(c) &= (m \circ (\eta \varepsilon \otimes f) \circ \Delta)(c)\\ &=(m \circ (\eta \otimes f) \circ (\varepsilon \otimes \operatorname{id}) \circ \Delta)(c)\\ &= (m \circ (\eta \otimes f))(1_{\mathbb K} \otimes c)\\ &= m(\mathbf 1 \otimes f(c))\\ &= f(c), \end{align} hence $\eta\varepsilon \star f = f$. Similarly one shows $f \star \eta\varepsilon = f$.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 1.0000044107437134, "perplexity": 649.4772339392777}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-35/segments/1440644065954.23/warc/CC-MAIN-20150827025425-00157-ip-10-171-96-226.ec2.internal.warc.gz"}
https://cs.stackexchange.com/questions/37818/language-consisting-of-all-turing-machine-encodings?noredirect=1	# Language consisting of all Turing machine encodings [closed] $A=${$⟨M⟩$:$M$ $is$ $a$ $Turing$ $Machine$ } What can be said about $A$ ? Specifically, is $A$ decidable,regular,CFL,CSL? I would say $A$ is decidable since we can write an algorithm to check whether a string is a valid encoding of a Turing machine . But, is $A$ Regular[or CFL or CSL] ? Edit : Someone argued that he could make an encoding where all the possible strings(What would be the alphabet here?-same as the encoding I suppose) are valid encoding of a TM(since there is a one-to-one correspondence between two countable infinite sets), hence making $A$ regular . • Under any reasonable encoding, $A$ is decidable, but in order to say anything more, you need to fix an encoding. – Yuval Filmus Jan 31 '15 at 22:41 • Under one encoding, all strings are encodings of Turing machines. Under others, the encoding is so complicated that it is not even context-free. It depends on the encoding. If the question doesn't specify the encoding, the answer is: "it depends on the encoding". – Yuval Filmus Jan 31 '15 at 22:51 • Enumerate all Turing machines. As the encoding of an arbitrary Turing machine, use the number of the machine denoted in unary. Every unary number is now the encoding of a Turing machine, by definition. So the language of the encodings is $1^*$ (or $1^+$). – reinierpost Jan 31 '15 at 22:58 • The question does have an answer – it depends on the encoding. – Yuval Filmus Jan 31 '15 at 23:13 • Well, may be you could add it as an answer. – PleaseHelp Jan 31 '15 at 23:19 The complexity of $A$ depends on the encoding used for Turing machines. It is easy to come up with an encoding in which every string encodes some Turing machine (there are lots of ways). In contrast, it is easy to come up with artificially "hard" encodings, say the $k$th Turing machine being encoded by $1^kb$, where $b=1$ iff the $k$th Turing machine halts on the empty input; under this encoding, $A$ is not decidable. Nevertheless, it seems intuitively clear that any reasonable encoding makes $A$ decidable, though it's hard to say anything more without knowing the exact encoding.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9408840537071228, "perplexity": 422.7252266556905}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178373095.44/warc/CC-MAIN-20210305152710-20210305182710-00116.warc.gz"}
https://gsn.com.br/r5yianb/gross-margin-vs-net-margin-2b6017	There are a number of metrics and corresponding financial ratios that are used to measure profitability. That loss, however, may just be a temporary issue for the company. A common size income statement is an income statement in which each line item is expressed as a percentage of the value of sales, to make analysis easier. This means that the carpenterâs gross margin rate is 4.67%, i.e. Investopedia requires writers to use primary sources to support their work. Gross margin and net margin are profitability ratios used to assess the financial well being of a company. U.S. Securities & Exchange Commission. Margin vs. Profit Infographics The gross, the operating, and the net profit margin are the three main margin analysis measures that are used to intricately analyze the income statement activities of a â¦ Sometimes the terms gross margin and gross profit are used interchangeably, which is a mistake. Gross profit marginÂ is shown as a percentage while gross profit is an absolute dollar amount.Â, It is important to note theÂ difference between gross profit margin andÂ gross profit. Gross profit margin is the gross profit divided by total revenue, multiplied by 100, to generate a percentage of income retained as profit after accounting for the cost of goods. Software companies tend to have Gross margins as high as 80~90%. Cost of goods sold (COGS) is defined as the direct costs attributable to the production of the goods sold in a company. Gross profit margin (gross margin) and net profit margin (net margin) are used to determine how well a company's management is generating profits. Reasons for losses could be increases in the cost of laborÂ and raw materials, recessionary periods, and the introduction of disruptive technological tools that could affect the company's bottom line. It's important for investors to compare the profit margins over several periods and against companies within the same industry. Gross profit is the least informative, then operating profit, and finally net profit. A critical point in gross margin vs net margin is that the former is derived after only deducting the cost of goods sold (COGS) from total revenue. The gross margin return on investment (GMROI) is an inventory profitability ratio that analyzes a firm's ability to turn inventory into cash over and above the cost of the inventory. At first glance, the profit figure may appear impressive, but if the gross margin for the company is only 1%, then a mere 2% increase in production costs is sufficient enough to make the company lose money. Gross margin is expressed as a percentage.Generally, it is calculated as the selling price of an item, less the cost of goods sold (e. g. production or acquisition costs, not including indirect fixed costs like office expenses, rent, or administrative costs), then divided by the same selling price. The balance sheet, cash flow statement and profit and loss statement -- also called an income statement -- are tools that give the analyst the big picture. Gross vs. Net Profit Companies may use TTM gross profit margin or TTM net profit margin to hone in on specific performance areas of interest. Both gross profit margin and net margin or net profit margin are expressed in percentage terms and measure profitability as compared to revenue for a period. As shown in the statementÂ above, Apple's gross profit figureÂ wasÂ $88 billion (or$229 billionÂ minus $141 billion).ï»¿ï»¿, In short, gross profitÂ is the total number of gross profit afterÂ subtracting revenue fromÂ COGSâorÂ$88 billion in the case of Apple. The Blueprint shows you how to calculate this ratio. Using the formula above, we can calculate it as: ï»¿$48B$229B=0.21\begin{aligned} &\frac{\text{\$48B}}{\text{\$229B}}=0.21\\ &0.21100 = 21\% \end{aligned}â$229B$48Bâ=0.21âï»¿, A 21% net profit margin indicates that for every dollar generated by AppleÂ in sales, the company keptÂ $0.21Â as profit.Â A higher profit margin is always desirable since it means the company generates more profits from its sales.Â. Gross Profit Margin vs. Operating Profit Margin vs. Net Profit Margin. To delve into profit margins a little more deeply, letâs compare the 3 major profit margins â gross, operating, and net. Definition of Gross Profit Margin. Accessed July 29, 2020. Net income is often called the bottom line for a company or the net profit. Gross Profit Margin is also referred to as Gross Margin or Gross Profit. A net profit margin of 23% means that for every dollar generated by Apple in sales, the company kept$0.23 as profit. Apple's net sales or revenue was $61 billion, and their cost of sales or cost of goods sold was$37.7 billion for the period. What Is the Difference Between Gross Profit Margin and Net Profit Margin? Expressed as a percentage, the net profit margin shows how much of each dollar collected by a company as revenue translates into profit. How to calculate Gross Margin. Gross profit margin provides a general indication of a company's profitability, but it isÂ not a precise measurement. The offers that appear in this table are from partnerships from which Investopedia receives compensation. While they measure similar metrics, gross margin measures the percentage (or dollar amount) of the comparison of a product's cost to its sale price, while gross profit measures the percentage (or dollar amount) of profit from the sale of the product. [4] X Research source The Gross Margin is based on the Gross Profit made by the company upon Net Sales. Both gross profit margin and net margin or net profit margin are expressed in â¦ Gross margin and net margin are profitability ratios used to assess the financial well being of a company. Much like the difference between gross profit and net profit, comparing gross margin vs. net margin is most easily understood when you think of them as a single metric, where the only difference is whether you want your calculation to consider all business expenses or just the cost of goods sold (COGS). To calculate the profit margin, divide the net income for the business by the total amount of sales, and multiply by 100 to arrive at a percentage. The net profit margin is the ratio of net profits toÂ revenuesÂ for a company or business segment. Let us look at these two profit margin measures using a historical example. "Form 10-K, Apple Inc.," Page 26. Gross Profit Margin (GP Margin) or Gross Margin is the measure which indicates that how well a company managed its major business activities (regarding material, labor, and direct expenses) so that the organization earns a profit. Gross Profit Margin vs. Net Profit Margin In Practice, Gross Margin Return on Investment: An Inside Look, Q2 FY18 Consolidated Financial Statements. As of March 31, 2018, Apple's net sales or revenue was $61 billion, and net income was$13.8B for the period. U.S. Securities & Exchange Commission. Thus, an alternate rendering of the gross margin equation becomes gross profit divided by total revenues. Consider the income statement below: Using the formula, the gross margin ratio would be calculated as follows: = (102,007 â 39,023) / 102,007 = 0.6174 (61.74%) This means that for every dollar generated, $0.3826 would go into the cost of goods sold while the remaining$0.6174 could be used to pay back expenses, taxes, etc. For example, if a business had total gross sales of $100,000 for the accounting period, and reported a net profit of$10,000, the business had a 10 percent net profit margin. Apple's netÂ profit margin for 2017 was 21%. It is wise to compare the margins of companies within the same industry and over multiple periods to get a sense of anyÂ trends. Net income goes even further than net gross margin because you deduct all other expenses, including overhead and taxes. It represents what percentage of sales has turned into profits. Gross Profit vs. Net Profit vs. Operating Profit Margin. Net profit is the gross profit (revenue minus COGS) minus operating expenses and all other expenses, such as taxes and interest paid on debt. Profit margin gauges the degree to which a company or a business activity makes money. Low Gross Profit Margin vs. Low Net Profit Margin. You can learn more about the standards we follow in producing accurate, unbiased content in our. Apple'sÂ gross profit margin for 2017 was 38%. The gross profit figure is of little analytical valueÂ because it is a number in isolation rather than a figure calculated in relation to both costs and revenue. Margin vs markup. Profit margin is a percentage measurement of profit that expresses the amount a company earns per dollar of sales. Gross Profit vs Gross Margin: Increasing Income So now we know that Joeâs Plumbing and Heating has a gross profit margin of 40% and a net profit margin of 8%. These include white papers, government data, original reporting, and interviews with industry experts. for each $100 of sales, the business has a net profit of$4.67. It is possible for a company to have a negative net profit margin. If a company makes more money per sale, it has a higher profit margin. Contribution Margin Example If a company has $2 million in revenue and its COGS is$1.5 million, gross margin would equal revenue minus COGS, which is â¦ DuPont analysis is a useful technique used to decompose the different drivers of return on equity (ROE). While gross profit and gross margin are two measurements of profitability, net profit margin, which includes a company's total expenses, is a â¦ So how does gross profit margin compare with regards to usefulness when compared with operating and net profit margins? Gross profit margin is computed by simply dividing net sales less cost of goods sold by net sales. Profitability ratios are financial metrics used to assess a business's ability to generate profit relative to items such as its revenue or assets. Gross profit margin is the proportion of money left over from revenues after accounting for the cost of goods sold (COGS). It is an extremely simple and straightforward metric to calculate. Gross Margin vs. A common size income statement is an income statement in which each line item is expressed as a percentage of the value of sales, to make analysis easier. Expressed as a percentage, the net profitÂ marginÂ shows how much of each dollar collected by a company as revenue translates to profit.Â, Net profitability is an important distinctionÂ since increases in revenue do not necessarily translate into increased profitability. Gross profit margin is a measure of profitability that showsÂ the percentage of revenueÂ that exceeds the cost of goods sold (COGS). However, profit margins can vary by industry. Profit margin gauges the degree to which a company or a business activity makes money. Gross profit describes a company's top line earnings; that is, its revenues less the direct costs of goods sold. You can learn more about the standards we follow in producing accurate, unbiased content in our. Profit margin is calculated as: Profit / Revenue. Gross profit margin and net profit margin, on the other hand, are two separate profitability ratios used to assess a company's financial stability and overall health. We also reference original research from other reputable publishers where appropriate. Gross margin is the difference between revenue and cost of goods sold (COGS), divided by revenue. A negative net profit margin occurs when a company hasÂ a loss for the quarter or year. While optimized net income is the bottom-line financial objective of for-profit companies, strong gross margin is a signal of financial health that contributes to ongoing profitability. To summarize, net margin and gross margin are two key financial performance indicators for â¦ Gross Margin = Revenue â COGS. These numbers will help Joe and his team set their financial goals for the coming year and formulate a plan to reach them. The former is the ratio of profit to the sale price and the latter is the ratio of profit to the purchase price (Cost of Goods Sold). COGS are raw materials and expenses associated directly with the creation of the company's primary product, not including overhead costs such as rent, utilities, freight, or payroll. While gross profit and gross margin are two measurements of profitability, net profit margin, which includes a company's total expenses, is a farÂ more definitive profitability metric, and the one most closely scrutinized by analysts and investors. You can think of markup as the extra percentage that you charge your customers (on top of your cost). You can also calculate Gross margin as a % value, meaning the percentage of the revenue that is left after COGS is deducted. The gross margin is always larger than the net margin, since the gross margin does not include any selling and administrative expenses. Net profit margin or net margin is the percentage of net income generated from a company's revenue. The gross profit margin is the percentage of revenueÂ that exceeds the COGS. As a simple example, a company with $100,000 in total sales and$65,000 in direct production-related costs has a gross margin of 35%. The companyâs Contribution Margin is: Net Sales of $450,000 minus the variable product costs of$130,000 and the variable expenses of $30,000 for a Contribution Margin of ($450,000-130,000-30,000) = $290,000. Gross profit is revenue less cost of goods sold. Below is the income statement for Apple Inc. (AAPL) as of March 31, 2018:. People often refer to net income as âthe bottom line,â as it â¦ Using the formula above, it would be calculated as follows: ï»¿($229Bâ$141B)$229Bâ100=38%\begin{aligned} &\frac{\left(\text{\$229B} - \text{\$141B}\right)}{\text{\229B}}100 = 38\% \end{aligned}â229B($229Bâ$141B)ââ100=38%âï»¿. If you bought an item for $20, sold it for$100, and Amazon took a cut of 15% ($15), you would have a profit of$65 and a profit margin of 65%: We also reference original research from other reputable publishers where appropriate. "Form 10-K, Apple Inc.," Page 39. The DuPont analysis is a framework for analyzing fundamental performance popularized by the DuPont Corporation. In short, the higher the number, the more efficient management is in generating profitÂ for every dollar of cost involved.Â, The gross profit margin is calculated by takingÂ total revenue minus the COGS and dividing the differenceÂ by total revenue.Â The gross margin resultÂ is typicallyÂ multiplied byÂ 100 to show the figure as a percentage.Â The COGS isÂ the amount it costs aÂ company to produce the goods or services that it sells.Â, ï»¿GrossÂ ProfitÂ Margin=(RevenueâCOGS)RevenueÃ100where:\begin{aligned} &\text{Gross Profit Margin} = \frac{\left(\text{Revenue} - \text{COGS}\right)}{\text{Revenue}}\times100\\ &\textbf{where:}\\ &\text{COGS}=\text{Cost of goods sold} \end{aligned}âGrossÂ ProfitÂ Margin=Revenue(RevenueâCOGS)âÃ100where:âï»¿, For the fiscal year endingÂ September 30, 2017, Apple reported total sales or revenueÂ of $229 billion and COGS of$141Â billion as shown from the company's consolidated 10K statement below.ï»¿ï»¿. Resultantly, a companyâs gross margin is always higher in comparison to its net margin. Gross margin vs. Net margin. Expressed as a percentage, the net profit margin shows how much of each dollar collected by a company as revenue translates into profit. A high gross profit margin indicates that a company is successfully producing profit over and above its costs. "Q2 FY18 Consolidated Financial Statements," Page 1. Let us start out by listing the pros for using the gross profit margin metric. The net profit margin is the ratio of net profits to revenuesÂ for a company; it reflects how much each dollar of revenue becomes profit. Apple. The net profit margin takes into account all business expenses, not merely COGS, and is, therefore, a more stringent metric by which to measure profitability. It represents what percentage of sales has turned into profits. It has multiple variants, namely Gross margin, Operating Margin, and Net profit margin, whereas when it comes to absolute dollar terms to measure the profit, we have Gross profit, Operating profit, and Net profit. Your Net Profit Margin is also a percentage derived from an equation that shows what cashremains from your gross profit (revenue minus cost of goods) after your operating expenses and all other expenses, such as taxes and interest paid on debt have been deducted. Profit Margin. The margin is calculated as a percentage term. The gross profit margin formula is the same as the net profit formula except that gross profit is used in lieu of net profit. The gross margin ratio helps businesses understand their profitability, considering gross profit and net sales. Growth companies might have a higher profit margin than retail companies, but retailers make up for their lower profit marginsÂ with higher sales volumes. Gross profit marginÂ is shown as a percentage while gross profit is an absolute dollar amount.Â, The gross profit is the absolute dollar amount of revenue that a company generates beyond its direct production costs. There are three financial statements that are used to analyze a business's efficiency. Using the previous example, a net income of $500 compared to$10,000 revenue would yield a net profit margin of 5 percent. Net profit margin equals net income divided by revenue. The gross profit margin reflects how successful a company's executive management team is in generating revenue, considering the costs involved in producing their products andÂ services. Net margin/sales x 100 = net margin rate. Profit margins are a measure of how efficient a company is at turning sales into profits by comparing revenues to costs of goods sold. It is the ratio of Gross profit / Total sales, which in the above example would be equal to $2500 /$5000 = 50%. Therefore, the gross profit margin (or gross margin) isÂ more significant for marketÂ analystsÂ and investors. Cost of goods sold are the specific costs incurred to produce the products sold during the accounting period. These include white papers, government data, original reporting, and interviews with industry experts. Image by Sabrina Jiang © Investopedia 2020. Calculate Gross Profit Margin. The difference between gross margin and markup is small but important. The Gross Margin or Gross Profit Percentage is the Gross Profit of $120,000 divided by$450,000 (net sales), or 26.66%. Gross margin and net income have an indirect, but strongly connected, relationship in a company's profit structure. The calculation of Gross Margin is pretty simple and straightforward. For example, if a product sells for $500 & costs$400 to produce, its margin would be calculated as $100. Investopedia requires writers to use primary sources to support their work. This means that for every dollar AppleÂ generatedÂ in sales, the company generatedÂ 38 cents in grossÂ profit before other business expenses wereÂ paid.Â A higher ratio is usually preferred, as this would indicate that the company is selling inventory for a higher profit. If expressed in percentage terms, the margin percentage will be 20% (calculated as the gross-margin divided by total sales, i.e., 100/500). Here's a more in-depth look at gross profit margin and net profit margin.$700/15,000 X 100 = 4.67%. Net profit margin further removes the values of interest, taxes, and operating expenses from net revenue to arrive at a more conservative figure. Net profit is divided by total revenue and multiplied by 100 to yield a percentage of income that remains after all expenses. The gross margin return on investment (GMROI) is an inventory profitability ratio that analyzes a firm's ability to turn inventory into cash over and above the cost of the inventory. Net profit reflects the total revenue left over after accounting for all outgoing cash flow and additional income streams including COGS, other operational expenses, debt payments such as interest, investment income, income from secondary operations, and one-time payments for unusual events such as lawsuits and taxes. Although it may appear more complicated, net profit is calculated for us and provided on the income statement asÂ net income.Â, ï»¿NetÂ ProfitÂ Margin=(NI)Ã100Revenuewhere:NI=NetÂ incomeR=RevenueOE=OperatingÂ expensesO=OtherÂ expensesI=Interest\begin{aligned} &\text{Net Profit Margin}=\frac{\left( NI \right)\times100} {\text{Revenue}}\\ &\textbf{where:}\\ &\begin{aligned} \text{NI}&=\text{Net income}\\ &=\text{R}\ -\ \text{COGS}\ -\ \text{OE}\ -\ \text{O}\ -\ \text{I}\ -\ \text{T}\end{aligned}\\ &\text{R}=\text{Revenue}\\ &\text{OE}=\text{Operating expenses}\\ &\text{O}=\text{Other expenses}\\ &\text{I}=\text{Interest}\\ &\text{T}=\text{Taxes} \end{aligned}âNetÂ ProfitÂ Margin=Revenue(NI)Ã100âwhere:NIâ=NetÂ incomeâR=RevenueOE=OperatingÂ expensesO=OtherÂ expensesI=Interestâï»¿, Apple reported a net income number of roughly48 billion (highlighted in blue) for the fiscal year ending September 30, 2017, as shown from its consolidated 10K statement below.Â As we saw earlier, Apple'sÂ total sales or revenue wasÂ $229 billion for the same period.ï»¿ï»¿. 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https://electronics.stackexchange.com/questions/24598/why-should-a-circuit-be-grounded?noredirect=1	# Why should a circuit be grounded? Why should a transistor circuit be grounded? The way I understand it is that ground is an infinite supply of electrons and so it is equivalent to the negative terminal of a battery. But in this page , there is both a negative terminal and the circuit is also grounded. If I've understood rightly, for a circuit to be complete, we need a positive terminal, some circuit elements & a negative terminal. If grounding is equivalent to a negative terminal, why do we need it in the circuit shown above? (By the way, all the circuits in the book I'm referring were not grounded until transistors started off. You could say that added to the confusion) • The concept of a relative ground becomes interesting when you're dealing with many different circuits, powered by a variety of supplies, and sharing data signals. A few years ago we built an interactive exhibit (demonstrating carbon capture and storage), which incorporated a good dozen PSUs of varying dc voltages, as well as a National Instruments chassis driving some signal and data cards. Only when every 'ground' on every circuit was strapped to the NI DAQ chassis ground, did the exhibit work. (Most DC adaptors have a plastic earth pin on the mains plug: they aren't even interested in 'real' – Peter Reid Jan 20 '13 at 18:17 The term "ground" can mean different things. When a circuit is looked at locally, ground is simply the one net someone picked to call 0V so that all other voltages are understood to be relative to it. Voltage is after all a relative concept. There is no such thing as 20V absolute, only 20V here with respect to there. "Ground" is a handy short form for a common there so you don't have to keep saying it. Such a ground is often chosen to be the negative supply voltage. That makes other voltages positive, which just makes things mentally easier. In general you try to chose ground as the point in the circuit signals and the like are referenced to by individual subsections. Usually there is a clear and obvious choice. Sometimes you just have to pick one. The other "ground" refers to real earth potential, or at least the potential of the general surroundings. This matters when power and signals are coming from or going outside your little circuit. For power and saftey, you have to assume a user could be tied to this ground, and you have to make sure you don't have a dangerous potential to ground to avoid zapping someone. Earth ground can also matter for radio systems since some types of antennas actually use the earth as part of the overall antenna system. • A finite amount of energy would be required to propel an electron an infinite distance from a proton. As such, one could define "absolute zero volts" as the energy of a proton that was infinitely far from an electron, and define other voltages relative to that. I think a more useful analogy might be elevation; one could define elevation in terms of distance from the center of the earth, and could theoretically measure a person's stature by subtracting the elevation of their feet from that of their head, but it's much more practical... – supercat Jan 5 '12 at 16:14 • ...to measure the distance between their head and feet directly. In the case of voltages, the level of uncertainty in any absolute-voltage measure would far exceed any relative voltages of interest. The absolute measure exists conceptually, but not as something practically useful. – supercat Jan 5 '12 at 16:16 • As an example for there, a voltage meter takes the difference between the two leads. In this way, the voltage read on the meter screen is the potential difference relative to the other lead. More often than not, one of the leads you use is going to be the point in your circuit that you have defined as ground. – sherrellbc Jun 21 '14 at 1:54 • Also note that from a mathematical standpoint, voltage is nothing more than the energy required to move a unit charge (1 C) from one point to another. The other point being the your point of interest and the former point often being ground. Voltage is measured in units of Joules/Coulomb (J/C). From wiki: voltage [is] work done per unit charge against a static electric field to move the charge between two points. – sherrellbc Jun 21 '14 at 1:56 From a circuit perspective, ground is relative - it is just a name for a wire (trace, net, node, etc) which other things may be measured or driven in reference to. As such it's largely arbitrary - for example, there are (or at least were) motor vehicles where the positive battery terminal rather than the negative was connected to the chassis ground. The addition of a ground symbol in your book at the same point in time when transistors were introduced is either a coincident change of style, or a general increase in the sophistication of the diagrams at a point when the complexity is increasing and thus making organizing principles such as the idea of a "ground node" more valuable. In a communication circuit, especially a radio, "ground" may have some literal meaning or at the least implication of connection to an earth ground (potentially a conductive stake driven far into the ground, possibly with the surrounding soil chemically treated if it's not sufficiently conductive). But that may not be reliably true for a handheld walkie-talkie, and it's certainly not true for an aircraft radio installation - in fact the potential of the aircraft "ground" might become quite different from that of the ground "ground" during the flight. But while in circuitry we think of "ground" as purely relative, in chemistry and physics, there is a concept of neutral charge which actually is absolute. A neutral charge is what you would have in an atom or molecule with an equal number of protons and electrons, or some larger unit of matter with equal net numbers. The absolute charge of an object determines the right-hand-rule force it would experience if moving through a magnetic field, while the charge relative to another nearby charge will determine the electric field (and resulting force) set up between the two. Because we can also create an electric field between between two points in a circuit, it might be tempting to think of "ground" as having neutral charge, but ultimate there is nothing that says that must be the case. Indeed, relative to the atmosphere, the earth has negative charge, though I'm not finding a ready answer as to the absolute charge of earth, meaningful atmosphere, or the two taken together. Presumably we are slightly subject to the sun's magnetic field, so if the earth had a substantial enough net charge it would cause some orbital perturbation, but then the subject of solar magnetism is hugely complicated - including the field loops called sunspots which have their own more obvious effects on radio communications and long wires here on earth... • So that means a ground does not mean a negative terminal as I've mentioned in my question. Its something like a 0 level for measuring potential differences. If I measure the potential difference between the ground & the positive terminal of a cell, then the ground acts as a negative terminal equivalent. If I do the same thing for the negative terminal, the ground now acts like a positive terminal equivalent. Have I got the concept right? – Green Noob Jan 5 '12 at 7:55 • Even then, I do not recognize the significance of mentioning the ground in the circuit diagram. Can you clarify please? – Green Noob Jan 5 '12 at 7:56 • The real significance of ground generally comes not from it being called "ground" but from what you connect to it. If you connect it to the negative battery terminal, you can measure a positive voltage between the positive terminal and ground; if you connect ground to the positive battery terminal, you can measure a negative voltage between ground and the negative terminal. Often the choice of what point in your circuit to call ground is purely for organization or preference, though there may be a few special cases where physics makes one situation more advantageous than another. – Chris Stratton Jan 5 '12 at 14:36 • Additionally, if you have an isolated circuit (battery powered, not touching anything conductive) there is absolutely no electrical significance to placing a single ground symbol on its diagram. However, if you place two symbols, the idea is that they are connected by some physical wire (perhaps the enclosure itself) which is not shown on the diagram. More advanced circuits will invent additional symbols for undrawn wires - typically supply voltages, and occasionally named signals which show up again at various places in the circuit which it would be messy to connect with drawn lines. – Chris Stratton Jan 5 '12 at 14:39 • @Kortuk - yes, but that's only meaningful because the power source has established an idea of what "ground" is, which you inherit when you decide to use that power source. With a different power source there would be a different idea. With batteries, or a common isolated 2-wire external supply, there isn't an external ground connection available to inherit. – Chris Stratton Jan 5 '12 at 15:54 Chris provided a more complex answer, so I'll make simple one. This confusion is manly a problem of English language using same name for different concepts. In say German, this strange new ground would be called mass and is a bit different than real ground. Basically the mass is just a convenient node in the circuit. In theory it can be absolutely any node in the circuit (more on that in Chris's answer) but in practice, it's just a simpler way of showing the connection to negative terminal of the battery. For example take a look at this circuit. Here I connected battery negative terminal to ground an the diode cathode to the ground. That is same as this circuit where the cathode is explicitly connected to negative terminal of the battery. Another thing which usually comes with the mass is the one terminal voltage source. Take a look at this circuit. It's same as the other two, but here we don't see the battery at all. The advantage of using this approach is that you're now getting into real electronics and you can expect more complex circuits. They can get very quickly very complicated to read, so the one terminal voltage source and the "ground" symbols are used to show that the component is connected to battery. For example in this circuit, it's completely irrelevant to the circuit itself how the voltage source looks like and how the emitter of the transistor is connected to the negative terminal. • Often you have a separate ground connection to connect the case and shield of your device through the ground. This allows protection circuits and protects the users from the hot line shorting to the case and endangering the user. – Kortuk Jan 5 '12 at 15:14 Here are two funny pictures illustrating a gravitational ground... ... and an electrical ground. Grouding and Earthning in wider sense are the same concepts.they are the concepts related to relative voltage.whenever we take something w.r.t 0 volts(null potential) it is referred to as grounding.for ex.lets consider 5V.It means negative plate is at 0V and positive is at 5V.This is w.r.t ground.And when we don't take w.r.t to ground it means that positive is at 2.5V and negative is at -2.5V which again makes it 2.5-(-2.5)=5V. Thus GROUNDING is nothing but the reference what we are taking w.r.t 0V.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7382438778877258, "perplexity": 604.9392533751335}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027320156.86/warc/CC-MAIN-20190824084149-20190824110149-00382.warc.gz"}
https://socratic.org/questions/why-chelate-compounds-are-stable-than-nonchelated-compounds	Chemistry Topics # Why chelate compounds are stable than nonchelated compounds? Dec 3, 2016 Well, to compare them on equal footing, we would be considering the same bonds being made with each kind of compound. Consider the following reaction: ["M"("NH"_3)_6]^(z+) + 3(en) rightleftharpoons ["M"(en)_3]^(z+) + 6"NH"_3 where $e n$ is ethylenediamine: Visually, at first glance, the only difference between $e n$ and ${\text{NH}}_{3}$ is that $e n$ has a $- {\text{CH"_2-"CH}}_{2} -$ bridge connecting the two nitrogens, and that both "teeth" on $\boldsymbol{e n}$ bind to the same metal. (They both have the same atoms that bind, and they both contribute zero charge.) This will therefore have a net zero enthalpy for the breaking and formation of the six $\text{M"-"N}$ interactions, because each of the six ${\text{NH}}_{3}$'s would form one $\text{M"-"N}$ interaction, but each of the three $e n$'s would form two $\text{M"-"N}$ interactions. All that means is that enthalpy is not a significant stabilizing factor. The main difference we're looking for is that $e n$ is fixed to a cis configuration, so by binding via two "teeth", it is going to restrict its own mobility. Entropy is smaller with more restricted motion. Therefore, its entropy of bond formation is less positive, and the decrease in entropy due to the interaction corresponds to favoring $e n$ over ${\text{NH}}_{3}$ (since $\Delta {S}_{\text{rxn" = sum DeltaS_"bonds broken" - sum DeltaS_"bonds formed}}$). We call this the chelate effect, where the binding of a chelating ligand like $e n$ in comparison to $N {H}_{3}$ is entropically favorable. Hence, a chelating ligand creates a more entropically stable compound. ##### Impact of this question 349 views around the world	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 18, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8153607249259949, "perplexity": 1327.4484066181492}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-47/segments/1573496670268.0/warc/CC-MAIN-20191119222644-20191120010644-00239.warc.gz"}
http://maa.org/publications/books/calculus-gems?device=desktop	# Calculus Gems: Brief Lives and Memorable Moments ### By George F. Simmons Catalog Code: GEMS Print ISBN: 978-0-88385-561-4 376 pp., Hardbound, 2007 List Price: $55.00 MAA Member:$41.25 Series: Spectrum The first half of Calculus Gems, entitled Brief Lives, is a biographical history of mathematics from the earliest times to the late 19th century. The author shows that science—and mathematics in particular—is something that people do, and not merely a mass of observed data and abstract theory. The second half of the book contains nuggets that Simmons has collected from number theory, geometry, science, etc., which he has used in his mathematics courses. Preface The Ancients The forerunners The Early Moderns The Mature Moderns Memorable Mathematics Index	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4949997365474701, "perplexity": 6403.81011874512}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738662133.5/warc/CC-MAIN-20160924173742-00017-ip-10-143-35-109.ec2.internal.warc.gz"}
https://oggm.org/tutorials/master/notebooks/construction/dynamical_spinup.html	# Dynamic spinup and dynamic $$\mu^$$ calibration for past simulations# This notebooks has not yet been fully updated to be compatible with OGGM v1.6. Thus it does not run for the moment, but we are working on it! New in version 1.5.3 resp. version 1.6.0! One of the issues glacier modellers facing is that the past state of glaciers is unknown. On the other side, more global datasets of past observations get available (e.g. geodetic mass balance), which can help constrain the recent past evolution. Reconstructing the past states of glaciers on a century timescale turns out to be a really difficult task, and OGGM team member Julia Eis spent her entire PhD thesis doing just that (see this paper for the theory and this one for the application). However, running simulations in the recent past can be quite useful for model validation. Also, more direct observations are available of glacier states of the recent past for constriction (e.g. area, geodetic mass balance). Further, a dynamical initialisation can release strong assumptions in the OGGM default settings: first that glaciers are in dynamical equilibrium at the glacier outline date (an assumption required for the ice thickness inversion) and second that the mass balance temperature sensitivity parameter ($$\mu^$$) is calibrated towards a geodetic mass balance ignoring a dynamically changing glacier geometry. In recent PRs (GH1342, GH1232, GH1361 and GH1425) we have released two new run tasks in OGGM which help with this issues: • The run_dynamic_spinup task, by default, aims to find a glacier state before the RGI-date (~10-30 years back) from which the glacier evolves to match the area given by the RGI-outline. Alternatively, it is also possible to use this task to match an observed volume. • The run_dynamic_mu_star_calibration task iteratively searches for a $$\mu^$$ to match the observed geodetic mass balance taking a dynamically changing glacier geometry into account. And of course, we want to match both things in the same past model run. Therefore by default in each iteration of run_dynamic_mu_star_calibration the run_dynamic_spinup function is included. A more in-depth explanation of the two tasks is provided in the next two chapters, which are followed by an example and a comparison of the different spinup options. ## High-level explanation of run_dynamic_spinup:# The dynamic spinup iteratively tries to find an initial glacier state in the past (t_start) that matches the area or the volume at the glacier outline date (t_end) under the historical climate forcing. To create changing initial glacier states, a constant mass balance is used (mb_spinup) together with a changing temperature bias. This mass balance defines an average mass balance between t_start and t_end. Afterwards, for the actual run, the method uses the OGGM default mass balance model (mb_historical). One iteration of the dynamic spinup looks like this: • Apply a temperature bias to mb_spinup. • Start with the glacier geometry after the ice thickness inversion and let the model evolve using mb_spinup for the same amount of time as the following historical run (= t_end - t_start). • The resulting glacier geometry is defined as the initial glacier state at t_start. • Now, let the glacier evolve using mb_historical from t_start until t_end • Get the model area or volume of the glacier at t_end. • Compare the model value to the reference value we want to meet. • If the difference is inside a given precision, stop the procedure and save the glacier evolution of this run. • If the difference is outside a given precision, change the temperature bias for mb_spinup and start over again (how the next guess is found is descript here). ### Two main problems why the dynamic spinup could not work:# The resulting glacier is too large, even when we start from a completely ice-free initial glacier state. Or the resulting glacier is too small and the algorithm tries to let the glacier grow outside the domain boundaries. The second problem could be met with a larger domain boundary (if available and enough memory resources are available). But for the first problem, no such solution is possible. To still try to cope with these two issues the dynamic spinup function tries to shorten the spinup period two times. The idea is with a shorter evolution time the glacier has less amount of time to grow/shrink and maybe do not encounter one of the two extremes. The minimum length of the spinup can be defined with min_spinup_period (default 10 years). If nothing helps and there is still an error (and if ignore_errors = True) the glacier geometry without a dynamic spinup is saved (= the glacier geometry after the ice thickness inversion). ### ¡Careful! This method is still a bit experimental. A few things to remember when using it:# • because of how the method works, glacier area and volume are not strictly the same at the glacier inventory date as after the inversion. We have checked that the errors are random: if you simulate many glaciers this should be fine (global plots on this point will follow soon). • because of the non-unique solutions to this optimization problem, the estimated past states become increasingly uncertain the further back in time we go. We recommend a spinup of about 10-30 years. ## High-level explanation of run_dynamic_mu_star_calibration :# This task iteratively searches for a $$\mu^$$ to match a given geodetic mass balance incorporating a dynamic model run. But changing $$\mu^$$ means we need to rerun all model setup steps which incorporate the mass-balance, to have one consistent model initialisation chain. In particular, we need to conduct the bed inversion again (the mass-balance is used in the flux calculation, see here). Therefore one default iteration of the dynamic $$\mu^$$ calibration looks like this: • define a new $$\mu^$$ in the glacier directory • conduct an inversion which calibrates to the consensus volume, still assuming dynamic equilibrium. (a little tricky: by default, before we start with the dynamic $$\mu^$$ calibration the first inversion with calibration on a regional scale was already carried out -> the individual glaciers do not match the consensus volume exactly, but when adding all glaciers of one region the consensus volume is matched. Therefore during this task, the individual glacier is again matched to the volume of the regional assessment and not on an individual basis.) • conduct a dynamic spinup to match the RGI area and let the model evolve up to the end of the geodetic mass balance period • calculate the modelled geodetic mass balance • calculate the difference between modelled value and observation • if the difference is inside the observation uncertainty stop and save the model run (indicated in diagnostics with used_spinup_option = dynamic mu_star calibration (full success)) • if the difference is larger, define a new $$\mu^$$ and start over again (how the next guess is found is described here) If the iterative search is not successful and ignore_errors = True there are several possible outcomes: • First, it is checked if there were some successful runs which improved the mismatch. If so, the best run is saved and it is indicated in the diagnostics with used_spinup_option = dynamic mu_star calibration (part success) • If only the first guess worked this run is saved and indicated in the diagnostics with used_spinup_option = dynamic spinup only • And if everything failed a fixed geometry spinup is conducted and indicated in the diagnostics with used_spinup_option = fixed geometry spinup If for whatever reason one wants to conduct the dynamic $$\mu^$$ calibration without an inversion or does not want to include a dynamic spinup, reach out to us as there are already options included for this. ## The minimization algorithm:# To start, a first guess of the control variable (temperature bias or $$\mu^$$) is used and evaluated. If by chance, the mismatch between model and observation is close enough, the algorithm stops already. Otherwise, the second guess depends on the calculated first guess mismatch. For example, if the first resulting area is smaller (larger) than the searched one, the second temperature bias will be colder (warmer). Because a colder (warmer) temperature leads to a larger (smaller) initial glacier state at t_start. If the second guess is still unsuccessful, for all consecutive guesses the previous value pairs (control variable, mismatch) are used to determine the next guess. For this, a stepwise linear function is fitted to these pairs and afterwards, the mismatch is set to 0 to get the following guess (this method is similar to the one described in Zekollari et al. 2019 Appendix A). Moreover, a maximum step length between two guesses is defined as too large step-sizes could easily lead to failing model runs (e.g. see here). Further, the algorithm was adapted independently inside run_dynamic_spinup and run_dynamic_mu_star_calibration to cope with failing model runs individually. Note that this minimization algorithm only works if the underlying relationship between the control variable and the mismatch is strictly monotone. If someone is interested in how this algorithm works in more detail, here is a conceptual code snippet: import numpy as np from scipy import interpolate def minimisation_algorithm( fct_to_minimise, # the function which should be minimised first_guess, # the first guess of the control variable get_second_guess, # function which gives the second guess depending on # the first mismatch precision_to_match, # we want to be smaller with the mismatch than this maxiter, # how many search iteration should be performed ): control_guesses = [] mismatch = [] # returns also the new control if some error management was going on inside # fct_to_minimise, not necessary new_mismatch, new_control = fct_to_minimise(first_guess) control_guesses.append(new_control) mismatch.append(new_mismatch) # check if we can stop already if abs(mismatch[-1]) < precision_to_match: return control_guesses, mismatch # how to get the second guess must also be defined by the user second_guess = get_second_guess(mismatch[-1]) new_mismatch, new_control = fct_to_minimise(second_guess) control_guesses.append(new_control) mismatch.append(new_mismatch) if abs(mismatch[-1]) < precision_to_match: return control_guesses, mismatch while len(control_guesses) < maxiter: # sort the (mismatch, control_pairs) from small to large sort_index = np.argsort(np.array(mismatch)) # actual linear fitting tck = interpolate.splrep(np.array(mismatch)[sort_index], np.array(control_guesses)[sort_index], k=1) # degree of the fitting, 1 is linear # if there are NaNs in the fitting parameters it is an indication that # probably the strictly monotone relation is not holding, but also # other problems possible (e.g. to close guesses) if np.isnan(tck[1]).any(): # here is the place where you can do further problem dependent # error management or just raise an error raise RuntimeError('Somthing went wrong during the linear fitting!') # evaluate the linear fit where mismatch = 0 to get the next guess next_control_guess = float(interpolate.splev(0, tck)) new_mismatch, new_control = fct_to_minimise(next_control_guess) control_guesses.append(new_control) mismatch.append(new_mismatch) if abs(mismatch[-1]) < precision_to_match: return control_guesses, mismatch # If we end here it was not possible to find a satisfying mismatch after maxiter(ations) raise RuntimeError('Could not find small enough mismatch after the' 'maximum iterations!') import matplotlib.pyplot as plt import xarray as xr import numpy as np import pandas as pd import seaborn as sns # Make pretty plots sns.set_style('ticks') sns.set_context('notebook') from oggm import cfg, utils, workflow, tasks, graphics cfg.initialize(logging_level='WARNING') cfg.PATHS['working_dir'] = utils.gettempdir(dirname='OGGMSpinup') 2023-03-10 19:38:31: oggm.cfg: Reading default parameters from the OGGM params.cfg configuration file. 2023-03-10 19:38:31: oggm.cfg: Multiprocessing switched OFF according to the parameter file. 2023-03-10 19:38:31: oggm.cfg: Multiprocessing: using all available processors (N=2) ## Define the glaciers we will play with# # Khumbu and a 'bad' glacier in terms of the dynamic spinup rgi_ids = ['RGI60-15.03733', 'RGI60-11.00275'] ## Preparing the glacier data# This can take up to a few minutes on the first call because of the download of the required data: # We use a recent gdir setting, calibated on a glacier per glacier basis base_url = 'https://cluster.klima.uni-bremen.de/~oggm/gdirs/oggm_v1.6/L3-L5_files/2023.1/elev_bands/W5E5/' # These parameters correspond to the settings of the base url #cfg.PARAMS['prcp_scaling_factor'] = 1.6 #cfg.PARAMS['climate_qc_months'] = 0 #cfg.PARAMS['hydro_month_nh'] = 1 #cfg.PARAMS['hydro_month_sh'] = 1 #cfg.PARAMS['max_mu_star'] = 600 # We use a relatively large border value to allow the glacier to grow during spinup gdirs = workflow.init_glacier_directories(rgi_ids, from_prepro_level=3, prepro_border=160, prepro_base_url=base_url) 2023-03-10 19:38:31: oggm.workflow: init_glacier_directories from prepro level 3 on 2 glaciers. 2023-03-10 19:38:31: oggm.workflow: Execute entity tasks [gdir_from_prepro] on 2 glaciers ## Start by comparing three different spinups# # For the following experiments we only use Khumbu gdir = gdirs[0] # We will "reconstruct" a possible glacier evolution from this year onwards spinup_start_yr = 1979 # here we save the original mu_star for later # and save some reference values we can compare to later area_reference = gdir.rgi_area_m2 # RGI area volume_reference = tasks.get_inversion_volume(gdir) # volume after regional calibration to consensus ref_period = cfg.PARAMS['geodetic_mb_period'] # get the reference period we want to use, 2000 to 2020 df_ref_dmdtda = utils.get_geodetic_mb_dataframe().loc[gdir.rgi_id] # get the data from Hugonnet 2021 df_ref_dmdtda = df_ref_dmdtda.loc[df_ref_dmdtda['period'] == ref_period] # only select the desired period dmdtda_reference = df_ref_dmdtda['dmdtda'].values[0] 1000 # get the reference dmdtda and convert into kg m-2 yr-1 dmdtda_reference_error = df_ref_dmdtda['err_dmdtda'].values[0] * 1000 # corresponding uncertainty --------------------------------------------------------------------------- ValueError Traceback (most recent call last) Cell In[10], line 5 2 spinup_start_yr = 1979 4 # here we save the original mu_star for later 7 # and save some reference values we can compare to later 8 area_reference = gdir.rgi_area_m2 # RGI area File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/utils/_workflow.py:3038, in GlacierDirectory.read_json(self, filename, filesuffix, allow_empty) 3021 def read_json(self, filename, filesuffix='', allow_empty=False): 3022 """Reads a JSON file located in the directory. 3023 3024 Parameters (...) 3035 A dictionary read from the JSON file 3036 """ -> 3038 fp = self.get_filepath(filename, filesuffix=filesuffix) 3039 if allow_empty: 3040 try: File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/utils/_workflow.py:2893, in GlacierDirectory.get_filepath(self, filename, delete, filesuffix, _deprecation_check) 2875 """Absolute path to a specific file. 2876 2877 Parameters (...) 2889 The absolute path to the desired file 2890 """ 2892 if filename not in cfg.BASENAMES: -> 2893 raise ValueError(filename + ' not in cfg.BASENAMES.') 2895 fname = cfg.BASENAMES[filename] 2896 if filesuffix: ValueError: local_mustar not in cfg.BASENAMES. Let’s start by comparing the fixed_geometry_spinup, the run_dynamic_spinup and the run_dynamic_mu_star_calibration (which contains a dynamic spinup) options. # ---- First do the fixed geometry spinup ---- fixed_geometry_spinup_yr=spinup_start_yr, # Start the run at the RGI date but retro-actively correct the data with fixed geometry output_filesuffix='_hist_fixed_geom', # where to write the output ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_hist_fixed_geom')) as ds: # ---- Second the dynamic spinup alone, matching area ---- spinup_start_yr=spinup_start_yr, # When to start the spinup minimise_for='area', # what target to match at the RGI date output_filesuffix='_spinup_dynamic_area', # Where to write the output ye=2020, # When the simulation should stop ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_area')) as ds: # ---- Third the dynamic spinup alone, matching volume ---- spinup_start_yr=spinup_start_yr, # When to start the spinup minimise_for='volume', # what target to match at the RGI date output_filesuffix='_spinup_dynamic_volume', # Where to write the output ye=2020, # When the simulation should stop ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_volume')) as ds: # ---- Fourth the dynamic mu star calibration (includes a dynamic spinup matching area) ---- ys=spinup_start_yr, # When to start the spinup ye=2020, # When the simulation should stop output_filesuffix='_dynamic_mu', # Where to write the output ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_dynamic_mu')) as ds: --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) Cell In[11], line 33 32 # ---- Fourth the dynamic mu star calibration (includes a dynamic spinup matching area) ---- 34 ys=spinup_start_yr, # When to start the spinup 35 ye=2020, # When the simulation should stop 36 output_filesuffix='_dynamic_mu', # Where to write the output 37 ); 39 with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_dynamic_mu')) as ds: AttributeError: module 'oggm.tasks' has no attribute 'run_dynamic_mu_star_calibration' # Now make a plot for comparision y0 = gdir.rgi_date + 1 f, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(16, 5)) ds_hist.volume_m3.plot(ax=ax1, label='Fixed geometry spinup'); ds_dynamic_mu.volume_m3.plot(ax=ax1, label='Dynamical mu* calibration'); ds_dynamic_spinup_area.volume_m3.plot(ax=ax1, label='Dynamical spinup match area'); ds_dynamic_spinup_volume.volume_m3.plot(ax=ax1, label='Dynamical spinup match volume'); ax1.set_title('Volume'); ax1.scatter(y0, volume_reference, c='C3', label='Reference values'); ax1.legend(); ds_hist.area_m2.plot(ax=ax2); ds_dynamic_mu.area_m2.plot(ax=ax2); ds_dynamic_spinup_area.area_m2.plot(ax=ax2); ds_dynamic_spinup_volume.area_m2.plot(ax=ax2); ax2.set_title('Area'); ax2.scatter(y0, area_reference, c='C3') ds_hist.length_m.plot(ax=ax3); ds_dynamic_mu.length_m.plot(ax=ax3); ds_dynamic_spinup_area.length_m.plot(ax=ax3); ds_dynamic_spinup_volume.length_m.plot(ax=ax3); ax3.set_title('Length'); ax3.scatter(y0, ds_hist.sel(time=y0).length_m, c='C3') plt.tight_layout() plt.show(); # and print out the modeled geodetic mass balances for comparision def get_dmdtda(ds): yr0_ref_mb, yr1_ref_mb = ref_period.split('_') yr0_ref_mb = int(yr0_ref_mb.split('-')[0]) yr1_ref_mb = int(yr1_ref_mb.split('-')[0]) return ((ds.volume_m3.loc[yr1_ref_mb].values - ds.volume_m3.loc[yr0_ref_mb].values) / gdir.rgi_area_m2 / (yr1_ref_mb - yr0_ref_mb) * cfg.PARAMS['ice_density']) print(f'Reference dmdtda 2000 to 2020 (Hugonnet 2021): {dmdtda_reference:.2f} +/- {dmdtda_reference_error:6.2f} kg m-2 yr-1') print(f'Fixed geometry spinup dmdtda 2000 to 2020: {get_dmdtda(ds_hist):.2f} kg m-2 yr-1') print(f'Dynamical spinup match area dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_spinup_area):.2f} kg m-2 yr-1') print(f'Dynamical spinup match volume dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_spinup_volume):.2f} kg m-2 yr-1') print(f'Dynamical mu* calibration dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_mu):.2f} kg m-2 yr-1') --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[12], line 7 4 f, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(16, 5)) 6 ds_hist.volume_m3.plot(ax=ax1, label='Fixed geometry spinup'); ----> 7 ds_dynamic_mu.volume_m3.plot(ax=ax1, label='Dynamical mu* calibration'); 8 ds_dynamic_spinup_area.volume_m3.plot(ax=ax1, label='Dynamical spinup match area'); 9 ds_dynamic_spinup_volume.volume_m3.plot(ax=ax1, label='Dynamical spinup match volume'); NameError: name 'ds_dynamic_mu' is not defined The blue curve shows the fixed geometry spinup (the old default spinup option). This option ignores area and length changes before the RGI date, which would be important, especially for hydrologic applications. Further, the short advance after the RGI date you see in the length is an “initial shock” after allowing the geometry to change. On the other side, the advantage of this method is that we match the area at the RGI date exact (red dot). And also the volume is matched perfectly because it is calculated backwards from the RGI date by using the constant area. The reference value of the length in these plots should not be considered as an observation as we are using an elevation band flowline, which loses some geometric information during the construction (see documentation). Both dynamic spinup options (matching the area in green, matching the volume in red) address the issues of constant geometry and the “initial shock”. With this method, we get a changing surface geometry before the RGI date without an “initial Shock” afterwards. You also see clearly that depending on the variable to match, we are closer to the reference area or the reference volume. Which option to use depends on the use case and the available data. On a global scale, we selected to match to the area by default. A reason for this is that the area is a direct observation, whereas the volume is a consensus model derivation (Farinotti 2019). Also shown in the plots above is the dynamic $$\mu^$$ calibration (including a dynamic spinup matching the area) in orange. However, you can not see an orange curve as it is exactly below the dynamic spinup matching the area (in green). The reason for this can be explained by comparing the reference geodetic mass balance (Hugonnet 2021) with the modelled ones, below the plots. You see that (by chance) the dynamic spinup already fits inside the provided observation uncertainty and therefore the dynamic $$\mu^$$ calibration does not need to look further. But to showcase the ability of the dynamic $$\mu^$$ calibration, we can artificially set the uncertainty lower and let it run again: # define an artificial error for dmdtda dmdtda_reference_error_artificial = 5 # error must be given as a positive number ys=spinup_start_yr, # When to start the spinup ye=2020, # When the simulation should stop output_filesuffix='_dynamic_mu_artificial', # Where to write the output ref_dmdtda=dmdtda_reference, # user-provided geodetic mass balance observation err_ref_dmdtda=dmdtda_reference_error_artificial, # uncertainty of user-provided geodetic mass balance observation ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_dynamic_mu_artificial')) as ds: --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) Cell In[13], line 4 1 # define an artificial error for dmdtda 2 dmdtda_reference_error_artificial = 5 # error must be given as a positive number 5 ys=spinup_start_yr, # When to start the spinup 6 ye=2020, # When the simulation should stop 7 output_filesuffix='_dynamic_mu_artificial', # Where to write the output 8 ref_dmdtda=dmdtda_reference, # user-provided geodetic mass balance observation 9 err_ref_dmdtda=dmdtda_reference_error_artificial, # uncertainty of user-provided geodetic mass balance observation 10 ); 12 with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_dynamic_mu_artificial')) as ds: AttributeError: module 'oggm.tasks' has no attribute 'run_dynamic_mu_star_calibration' # plot again y0 = gdir.rgi_date + 1 f, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(16, 5)) ds_hist.volume_m3.plot(ax=ax1, label='Fixed geometry spinup'); ds_dynamic_mu_artificial.volume_m3.plot(ax=ax1, label='Dynamical mu calibration'); ds_dynamic_spinup_area.volume_m3.plot(ax=ax1, label='Dynamical spinup match area'); ax1.set_title('Volume'); ax1.scatter(y0, volume_reference, c='C3', label='Reference values'); ax1.legend(); ds_hist.area_m2.plot(ax=ax2); ds_dynamic_mu_artificial.area_m2.plot(ax=ax2); ds_dynamic_spinup_area.area_m2.plot(ax=ax2); ax2.set_title('Area'); ax2.scatter(y0, area_reference, c='C3') ds_hist.length_m.plot(ax=ax3); ds_dynamic_mu_artificial.length_m.plot(ax=ax3); ds_dynamic_spinup_area.length_m.plot(ax=ax3); ax3.set_title('Length'); ax3.scatter(y0, ds_hist.sel(time=y0).length_m, c='C3') plt.tight_layout() plt.show(); # and print out the modeled geodetic mass balances for comparision def get_dmdtda(ds): yr0_ref_mb, yr1_ref_mb = ref_period.split('_') yr0_ref_mb = int(yr0_ref_mb.split('-')[0]) yr1_ref_mb = int(yr1_ref_mb.split('-')[0]) return ((ds.volume_m3.loc[yr1_ref_mb].values - ds.volume_m3.loc[yr0_ref_mb].values) / gdir.rgi_area_m2 / (yr1_ref_mb - yr0_ref_mb) * cfg.PARAMS['ice_density']) print(f'Reference dmdtda 2000 to 2020 (artificial error): {dmdtda_reference:.2f} +/- {dmdtda_reference_error_artificial:6.2f} kg m-2 yr-1') print(f'Fixed geometry spinup dmdtda 2000 to 2020: {get_dmdtda(ds_hist):.2f} kg m-2 yr-1') print(f'Dynamical spinup match area dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_spinup_area):.2f} kg m-2 yr-1') print(f'Dynamical mu* calibration dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_mu_artificial):.2f} kg m-2 yr-1') --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[14], line 7 4 f, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(16, 5)) 6 ds_hist.volume_m3.plot(ax=ax1, label='Fixed geometry spinup'); ----> 7 ds_dynamic_mu_artificial.volume_m3.plot(ax=ax1, label='Dynamical mu* calibration'); 8 ds_dynamic_spinup_area.volume_m3.plot(ax=ax1, label='Dynamical spinup match area'); 9 ax1.set_title('Volume'); NameError: name 'ds_dynamic_mu_artificial' is not defined It is a made-up example, but you see here is a difference between the dynamic spinup and the dynamic $$\mu^$$ calibration. And indeed the dynamic mu star calibration manages to match our ‘very accurate’ geodetic mass balance. For additional options of the two run tasks have a look at their doc-strings (run_dynamic_spinup and run_dynamic_mu_star_calibration). You can also change all the settings of the included dynamic spinup inside the run_dynamic_mu_star_calibration by using kwargs_run_function (e.g. kwargs_run_function = {'minimize_for':'volume'} to match for volume instead of area). ## Example where it is not working so well# The dynamic spinup however is not always working that well, as the example below shows: # now we switch to the 'bad' glacier gdir = gdirs[1] # We will "reconstruct" a possible glacier evolution from this year onwards spinup_start_yr = 1979 # here we save the original mu_star for later # and save some reference values we can compare to later area_reference = gdir.rgi_area_m2 # RGI area volume_reference = tasks.get_inversion_volume(gdir) # volume after regional calibration to consensus ref_period = cfg.PARAMS['geodetic_mb_period'] # get the reference period we want to use, 2000 to 2020 df_ref_dmdtda = utils.get_geodetic_mb_dataframe().loc[gdir.rgi_id] # get the data from Hugonnet 2021 df_ref_dmdtda = df_ref_dmdtda.loc[df_ref_dmdtda['period'] == ref_period] # only select the desired period dmdtda_reference = df_ref_dmdtda['dmdtda'].values[0] 1000 # get the reference dmdtda and convert into kg m-2 yr-1 dmdtda_reference_error = df_ref_dmdtda['err_dmdtda'].values[0] * 1000 # corresponding uncertainty --------------------------------------------------------------------------- ValueError Traceback (most recent call last) Cell In[16], line 5 2 spinup_start_yr = 1979 4 # here we save the original mu_star for later 7 # and save some reference values we can compare to later 8 area_reference = gdir.rgi_area_m2 # RGI area File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/utils/_workflow.py:3038, in GlacierDirectory.read_json(self, filename, filesuffix, allow_empty) 3021 def read_json(self, filename, filesuffix='', allow_empty=False): 3022 """Reads a JSON file located in the directory. 3023 3024 Parameters (...) 3035 A dictionary read from the JSON file 3036 """ -> 3038 fp = self.get_filepath(filename, filesuffix=filesuffix) 3039 if allow_empty: 3040 try: File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/utils/_workflow.py:2893, in GlacierDirectory.get_filepath(self, filename, delete, filesuffix, _deprecation_check) 2875 """Absolute path to a specific file. 2876 2877 Parameters (...) 2889 The absolute path to the desired file 2890 """ 2892 if filename not in cfg.BASENAMES: -> 2893 raise ValueError(filename + ' not in cfg.BASENAMES.') 2895 fname = cfg.BASENAMES[filename] 2896 if filesuffix: ValueError: local_mustar not in cfg.BASENAMES. # ---- First do the fixed geometry spinup ---- fixed_geometry_spinup_yr=spinup_start_yr, # Start the run at the RGI date but retro-actively correct the data with fixed geometry output_filesuffix='_hist_fixed_geom', # where to write the output ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_hist_fixed_geom')) as ds: # ---- Second the dynamic spinup alone, matching area ---- spinup_start_yr=spinup_start_yr, # When to start the spinup minimise_for='area', # what target to match at the RGI date output_filesuffix='_spinup_dynamic_area', # Where to write the output ye=2020, # When the simulation should stop ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_area')) as ds: # ---- Third the dynamic spinup alone, matching volume ---- spinup_start_yr=spinup_start_yr, # When to start the spinup minimise_for='volume', # what target to match at the RGI date output_filesuffix='_spinup_dynamic_volume', # Where to write the output ye=2020, # When the simulation should stop ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_volume')) as ds: 2023-03-10 19:38:54: oggm.core.dynamic_spinup: No dynamic spinup could be conducted and the original model with no spinup is saved using the provided output_filesuffix "_spinup_dynamic_area". The error message of the dynamic spinup is: Could not find mismatch smaller 1% (only 1.349507936627543%) in 30Iterations! 2023-03-10 19:38:54: oggm.core.dynamic_spinup: RuntimeError occurred during task run_dynamic_spinup_spinup_dynamic_area on RGI60-11.00275: Could not find mismatch smaller 1% (only 1.349507936627543%) in 30Iterations! --------------------------------------------------------------------------- RuntimeError Traceback (most recent call last) File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/core/dynamic_spinup.py:816, in run_dynamic_spinup(gdir, init_model_filesuffix, init_model_yr, init_model_fls, climate_input_filesuffix, evolution_model, mb_model_historical, mb_model_spinup, spinup_period, spinup_start_yr, min_spinup_period, spinup_start_yr_max, yr_rgi, minimise_for, precision_percent, precision_absolute, min_ice_thickness, first_guess_t_bias, t_bias_max_step_length, maxiter, output_filesuffix, store_model_geometry, store_fl_diagnostics, store_model_evolution, ignore_errors, return_t_bias_best, ye, model_flowline_filesuffix, make_compatible, add_fixed_geometry_spinup, kwargs) 815 try: --> 816 final_t_bias_guess, final_mismatch = minimise_with_spline_fit(c_fun) 817 # ok no error occurred so we succeeded File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/core/dynamic_spinup.py:761, in run_dynamic_spinup.<locals>.minimise_with_spline_fit(fct_to_minimise) 759 # Ok when we end here the spinup could not find satisfying match after 760 # maxiter(ations) --> 761 raise RuntimeError(f'Could not find mismatch smaller ' 762 f'{precision_percent}% (only ' 763 f'{np.min(np.abs(mismatch))}%) in {maxiter}' 764 f'Iterations!') RuntimeError: Could not find mismatch smaller 1% (only 1.349507936627543%) in 30Iterations! During handling of the above exception, another exception occurred: RuntimeError Traceback (most recent call last) Cell In[17], line 11 10 # ---- Second the dynamic spinup alone, matching area ---- 12 spinup_start_yr=spinup_start_yr, # When to start the spinup 13 minimise_for='area', # what target to match at the RGI date 14 output_filesuffix='_spinup_dynamic_area', # Where to write the output 15 ye=2020, # When the simulation should stop 16 ); 18 with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_area')) as ds: 490 ex_t = time.time() --> 491 out = task_func(gdir, kwargs) 492 ex_t = time.time() - ex_t File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/oggm/core/dynamic_spinup.py:845, in run_dynamic_spinup(gdir, init_model_filesuffix, init_model_yr, init_model_fls, climate_input_filesuffix, evolution_model, mb_model_historical, mb_model_spinup, spinup_period, spinup_start_yr, min_spinup_period, spinup_start_yr_max, yr_rgi, minimise_for, precision_percent, precision_absolute, min_ice_thickness, first_guess_t_bias, t_bias_max_step_length, maxiter, output_filesuffix, store_model_geometry, store_fl_diagnostics, store_model_evolution, ignore_errors, return_t_bias_best, ye, model_flowline_filesuffix, make_compatible, add_fixed_geometry_spinup, *kwargs) 842 if diag_path and os.path.exists(diag_path): 843 os.remove(diag_path) --> 845 raise RuntimeError(e) 847 # hurray, dynamic spinup successfully RuntimeError: Could not find mismatch smaller 1% (only 1.349507936627543%) in 30Iterations! # Now make a plot for comparision y0 = gdir.rgi_date + 1 f, (ax1, ax2, ax3) = plt.subplots(1, 3, figsize=(16, 5)) ds_hist.volume_m3.plot(ax=ax1, label='Fixed geometry spinup'); ds_dynamic_spinup_area.volume_m3.plot(ax=ax1, label='Dynamical spinup match area'); ds_dynamic_spinup_volume.volume_m3.plot(ax=ax1, label='Dynamical spinup match volume'); ax1.set_title('Volume'); ax1.scatter(y0, volume_reference, c='C3', label='Reference values'); ax1.legend(); ds_hist.area_m2.plot(ax=ax2); ds_dynamic_spinup_area.area_m2.plot(ax=ax2); ds_dynamic_spinup_volume.area_m2.plot(ax=ax2); ax2.set_title('Area'); ax2.scatter(y0, area_reference, c='C3') ds_hist.length_m.plot(ax=ax3); ds_dynamic_spinup_area.length_m.plot(ax=ax3); ds_dynamic_spinup_volume.length_m.plot(ax=ax3); ax3.set_title('Length'); ax3.scatter(y0, ds_hist.sel(time=y0).length_m, c='C3') plt.tight_layout() plt.show(); # and print out the modeled geodetic mass balances for comparision def get_dmdtda(ds): yr0_ref_mb, yr1_ref_mb = ref_period.split('_') yr0_ref_mb = int(yr0_ref_mb.split('-')[0]) yr1_ref_mb = int(yr1_ref_mb.split('-')[0]) return ((ds.volume_m3.loc[yr1_ref_mb].values - ds.volume_m3.loc[yr0_ref_mb].values) / gdir.rgi_area_m2 / (yr1_ref_mb - yr0_ref_mb) cfg.PARAMS['ice_density']) print(f'Reference dmdtda 2000 to 2020 (Hugonnet 2021): {dmdtda_reference:.2f} +/- {dmdtda_reference_error:6.2f} kg m-2 yr-1') print(f'Fixed geometry spinup dmdtda 2000 to 2020: {get_dmdtda(ds_hist):.2f} kg m-2 yr-1') print(f'Dynamical spinup match area dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_spinup_area):.2f} kg m-2 yr-1') print(f'Dynamical spinup match volume dmdtda 2000 to 2020: {get_dmdtda(ds_dynamic_spinup_volume):.2f} kg m-2 yr-1') --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[18], line 10 8 ds_dynamic_spinup_volume.volume_m3.plot(ax=ax1, label='Dynamical spinup match volume'); 9 ax1.set_title('Volume'); ---> 10 ax1.scatter(y0, volume_reference, c='C3', label='Reference values'); 11 ax1.legend(); 13 ds_hist.area_m2.plot(ax=ax2); NameError: name 'volume_reference' is not defined In this example, you see that the dynamic spinup runs do not start in 1980 but other years. The reason for this are the two main problems and the coping strategy of reducing the spinup time, described here in more detail. Be aware that even if you set a specific spinup year the resulting model run can start at a later year. If you want to get an error when this is happening you can use the min_spinup_period. For example you can set min_spinup_period = gdir.rgi_date - spinup_start_yr, with this an error is raised whenever it is not possible to run a dynamic spinup over the whole period. ## Dynamical spinup and hydrological output# Fortunately, it is also possible to run the spinup model with additional hydrological output: # Here we use Khumbu again gdir = gdirs[0] cfg.PARAMS['store_model_geometry'] = True # This is required for the hydro runs # Dynamic mu star calibration including a dynamic spinup to match for area ys=spinup_start_yr, # When to start the spinup ye=2020, # When the simulation should stop store_monthly_hydro=True, # compute monthly hydro diagnostics ref_area_from_y0=True, # Even if the glacier may grow, keep the reference area as the year 0 of the simulation output_filesuffix='_spinup_dynamic_hydro', # Where to write the output - this is needed to stitch the runs together afterwards ); with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_hydro')) as ds: ds_dynamic_spinup_hydro = ds_dynamic_spinup_hydro.isel(time=slice(0, -1)) # The last timestep is incomplete for hydro (not started) 2023-03-10 19:38:55: oggm.cfg: PARAMS['store_model_geometry'] changed from False to True. --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) Cell In[19], line 8 4 cfg.PARAMS['store_model_geometry'] = True # This is required for the hydro runs 6 # Dynamic mu star calibration including a dynamic spinup to match for area 9 ys=spinup_start_yr, # When to start the spinup 10 ye=2020, # When the simulation should stop 11 store_monthly_hydro=True, # compute monthly hydro diagnostics 12 ref_area_from_y0=True, # Even if the glacier may grow, keep the reference area as the year 0 of the simulation 13 output_filesuffix='_spinup_dynamic_hydro', # Where to write the output - this is needed to stitch the runs together afterwards 14 ); 17 with xr.open_dataset(gdir.get_filepath('model_diagnostics', filesuffix='_spinup_dynamic_hydro')) as ds: AttributeError: module 'oggm.tasks' has no attribute 'run_dynamic_mu_star_calibration' ### Annual runoff# The new hydrological variables are now available. Let’s make a pandas DataFrame of all “1D” (annual) variables: sel_vars = [v for v in ds_dynamic_spinup_hydro.variables if 'month_2d' not in ds_dynamic_spinup_hydro[v].dims] df_annual = ds_dynamic_spinup_hydro[sel_vars].to_dataframe() --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[20], line 1 ----> 1 sel_vars = [v for v in ds_dynamic_spinup_hydro.variables if 'month_2d' not in ds_dynamic_spinup_hydro[v].dims] 2 df_annual = ds_dynamic_spinup_hydro[sel_vars].to_dataframe() NameError: name 'ds_dynamic_spinup_hydro' is not defined The hydrological variables are computed on the largest possible area that was covered by glacier ice in the simulation. This is equivalent to the runoff that would be measured at a fixed-gauge station at the glacier terminus. The total annual runoff is: # Select only the runoff variables and convert them to megatonnes (instead of kg) runoff_vars = ['melt_off_glacier', 'melt_on_glacier', 'liq_prcp_off_glacier', 'liq_prcp_on_glacier'] df_runoff = df_annual[runoff_vars] * 1e-9 df_runoff.sum(axis=1).plot(); plt.ylabel('Mt'); --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[21], line 3 1 # Select only the runoff variables and convert them to megatonnes (instead of kg) 2 runoff_vars = ['melt_off_glacier', 'melt_on_glacier', 'liq_prcp_off_glacier', 'liq_prcp_on_glacier'] ----> 3 df_runoff = df_annual[runoff_vars] * 1e-9 4 df_runoff.sum(axis=1).plot(); plt.ylabel('Mt'); NameError: name 'df_annual' is not defined It consists of the following components: • melt off-glacier: snow melt on areas that are now glacier free (i.e. 0 in the year of largest glacier extent, in this example at the start of the simulation) • melt on-glacier: ice + seasonal snow melt on the glacier • liquid precipitaton on- and off-glacier (the latter being zero at the year of largest glacial extent, in this example at start of the simulation) f, ax = plt.subplots(figsize=(10, 6)); df_runoff.plot.area(ax=ax, color=sns.color_palette("rocket")); plt.xlabel('Years'); plt.ylabel('Runoff (Mt)'); plt.title(rgi_ids[0]); --------------------------------------------------------------------------- NameError Traceback (most recent call last) Cell In[22], line 2 1 f, ax = plt.subplots(figsize=(10, 6)); ----> 2 df_runoff.plot.area(ax=ax, color=sns.color_palette("rocket")); plt.xlabel('Years'); plt.ylabel('Runoff (Mt)'); plt.title(rgi_ids[0]); NameError: name 'df_runoff' is not defined As the glacier retreats, total runoff decreases as a result of the decreasing glacier contribution. ### Monthly runoff# The “2D” variables contain the same data but at monthly resolution, with the dimension (time, month). For example, runoff can be computed the same way: # Select only the runoff variables and convert them to megatonnes (instead of kg) monthly_runoff = ds['melt_off_glacier_monthly'] + ds['melt_on_glacier_monthly'] + ds['liq_prcp_off_glacier_monthly'] + ds['liq_prcp_on_glacier_monthly'] monthly_runoff = 1e-9 monthly_runoff.clip(0).plot(cmap='Blues', cbar_kwargs={'label':'Mt'}); plt.xlabel('Months'); plt.ylabel('Years'); plt.title(rgi_ids[0]); --------------------------------------------------------------------------- KeyError Traceback (most recent call last) File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/xarray/core/dataset.py:1347, in Dataset._construct_dataarray(self, name) 1346 try: -> 1347 variable = self._variables[name] 1348 except KeyError: KeyError: 'melt_off_glacier_monthly' During handling of the above exception, another exception occurred: KeyError Traceback (most recent call last) Cell In[23], line 2 1 # Select only the runoff variables and convert them to megatonnes (instead of kg) ----> 2 monthly_runoff = ds['melt_off_glacier_monthly'] + ds['melt_on_glacier_monthly'] + ds['liq_prcp_off_glacier_monthly'] + ds['liq_prcp_on_glacier_monthly'] 3 monthly_runoff = 1e-9 4 monthly_runoff.clip(0).plot(cmap='Blues', cbar_kwargs={'label':'Mt'}); plt.xlabel('Months'); plt.ylabel('Years'); plt.title(rgi_ids[0]); File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/xarray/core/dataset.py:1438, in Dataset.__getitem__(self, key) 1436 return self.isel(**key) 1437 if utils.hashable(key): -> 1438 return self._construct_dataarray(key) 1439 if utils.iterable_of_hashable(key): 1440 return self._copy_listed(key) File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/xarray/core/dataset.py:1349, in Dataset._construct_dataarray(self, name) 1347 variable = self._variables[name] 1348 except KeyError: -> 1349 _, name, variable = _get_virtual_variable(self._variables, name, self.dims) 1351 needed_dims = set(variable.dims) 1353 coords: dict[Hashable, Variable] = {} File /usr/local/pyenv/versions/3.10.10/lib/python3.10/site-packages/xarray/core/dataset.py:185, in _get_virtual_variable(variables, key, dim_sizes) 183 split_key = key.split(".", 1) 184 if len(split_key) != 2: --> 185 raise KeyError(key) 187 ref_name, var_name = split_key 188 ref_var = variables[ref_name] KeyError: 'melt_off_glacier_monthly' See hydrological_output for more info on how to interpret the hydrological output!	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4592759907245636, "perplexity": 10678.539526825065}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296945287.43/warc/CC-MAIN-20230324144746-20230324174746-00296.warc.gz"}
http://math.stackexchange.com/questions/441719/defining-the-coboundary-map-delta-on-the-sheaf-cech-cohomology-groups/441770	# Defining the coboundary map $\delta_$ on the Sheaf Cech Cohomology groups I'm having trouble understanding the definitions I've been reading, of what has been called an 'induced coboundary operator' or a 'connecting homomorphism' depending on what source you're reading. Firstly, the what I've been working with is the Cech Homology groups are induced by the coboundary operator. $$\check{H}^p(\mathcal{U},\mathscr{E}) = \frac{\ker(\delta:C^p(\mathcal{U},\mathscr{E}) \xrightarrow{} C^{p+1}(\mathcal{U},\mathscr{E}))}{\delta C^{p-1}(\mathcal{U},\mathscr{E})}$$ Where $\mathcal{U} = \{U_\alpha\}$ is a locally finite open cover of our manifold $M$. Initially we start with a short exact sequence of Sheaves $$0 \xrightarrow{} \mathscr{E} \xrightarrow{\alpha} \mathscr{F} \xrightarrow{\beta} \mathscr{G}\xrightarrow{} 0$$ This induces a map on the Cech cochain complexes $$C^p(\mathcal{U},\mathscr{E}) \xrightarrow{\alpha} C^p(\mathcal{U},\mathscr{F}) \xrightarrow{\beta} C^p(\mathcal{U},\mathscr{G})$$ Which consequently induces maps on the cohomology groups $$\check{H}^p(\mathcal{U},\mathscr{E}) \xrightarrow{\alpha_} \check{H}^p(\mathcal{U},\mathscr{F}) \xrightarrow{\beta_} \check{H}^p(\mathcal{U},\mathscr{G})$$ All these definitions are fine so far, the problem I encounter is the source I'm reading: "Griffiths & Harris - Principles of Algebraic Geometry", gives a very loose definition of the induced coboundary map $$\delta_:\check{H}^p(\mathcal{U},\mathscr{G}) \xrightarrow{} \check{H}^{p+1}(\mathcal{U},\mathscr{E})$$ The definition is contained within a proof of another theorem, it involves diagram chasing, yet is rather difficult to interpret. - I managed to adapt a proof I found in here involving relative homology groups. I will append a subscript $p$ to denote the maps from the respective cochain complexes and cohomology groups. We can define the map $\delta_{p}: \check{H}^{p}(\mathcal{U},\mathscr{G})\xrightarrow{} \check{H}^{p+1}(\mathcal{U},\mathscr{E})$ by taking $\sigma \in C^{p}(\mathcal{U},\mathscr{G})$ with $\delta_p \sigma = 0$, thus representing a cohomology class $[\sigma] \in \check{H}^{p}(\mathcal{U},\mathscr{G})$. Since the map $\beta_p$ is surjective, there is a $\tau \in C^{p}(\mathcal{U},\mathscr{F})$ such that $\beta_p(\tau) = \sigma$. Now $\delta_p(\tau) \in \ker(\beta_{p+1})$, since the diagram is commutative and $$\beta_{p+1} \delta_p \tau = \delta_p \beta_p(\tau) = \delta_p \sigma = 0$$ Using the exactness of the rows and injectivity of $\alpha$, we can say that there exists a unique $\lambda \in C^{p+1}(\mathcal{U},\mathscr{E})$ such that $\alpha_{p+1} (\lambda) = \delta_p(\tau)$ and again using commutivity, we can see that $$\alpha_{p+2} \delta_{p+1} \lambda = \delta_{p+1} \alpha_{p+1} \lambda = \delta_{p+1} \delta_p \tau = 0$$ Again, given $\alpha$ is injective, this implies $\delta_{p+1} \lambda = 0$ and $[\lambda] \in \check{H}^{p+1}(\mathcal{U},\mathscr{E})$. We define $\delta_{p} [\sigma] = [\lambda] \in \check{H}^{p+1}(\mathcal{U},\mathscr{E})$ $\square$ -	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9919447898864746, "perplexity": 224.44430028507665}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-15/segments/1397609533957.14/warc/CC-MAIN-20140416005213-00336-ip-10-147-4-33.ec2.internal.warc.gz"}
https://questions.examside.com/past-years/medical/question/in-the-following-reaction-hc-equiv-ch-mathrel-neet-chemistry-hydrocarbons-kvhfb3d87hiypgm7	1 NEET 2013 (Karnataka) In the following reaction : Product 'P' will not give A Tollen's reagent test B C Victor Meyer test D Iodoform test Explanation CH3CHO does not give Victor Meyer test. 2 NEET 2013 (Karnataka) Which of the following chemical system is non aromatic ? A B C D Explanation The molecules which do not satisfy Huckel rule or (4n + 2)$\pi$-electron rule are said to be non-aromatic. The compound (d) has four $\pi$ electrons. It does not follow (4n + 2)$\pi$ rule. So it is non-aromatic compound. 3 NEET 2013 Which of the following compounds will not undergo Friedal-Craft's reaction easily? A Nitrobenzene B Toluene C Cumene D Xylene Explanation Nitrobenzene is strongly deactivated, hence will not undergo Friedel-Crafts reaction. 4 AIPMT 2012 Mains Which of the following reagents will be able to distinguish between 1-butyne and 2-butyne? A NaNH2 B HCl C O2 D Br2	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8485808372497559, "perplexity": 13160.33072555382}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964362619.23/warc/CC-MAIN-20211203091120-20211203121120-00034.warc.gz"}
https://examproblems4lossmodels.wordpress.com/tag/pure-premium/	## Exam C Practice Problem 26 – A Limited Fluctuation Credibility Example Problem 26-A You are given the following about a large portfolio of insurance policies: • For each insurance policy, the annual number of claims follows a binomial distribution with $m$ = 3 and $q$ = 0.3. • The claim size follows an inverse Gamma distribution with $\alpha$ = 2.1 and $\theta$ = 3. • The number of claims and the claim sizes are independent. • The full credibility standard has been selected so that actual claim costs will be within 10% of expected claim costs 90% of the time. Using limited fluctuation credibility, determine the expected number of claims required for full credibility. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 460$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 790$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2895$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3715$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4600$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 26-B You are given the following about a large portfolio of insurance policies: • For each insurance policy, the annual number of claims follows a binomial distribution with $m$ = 6 and $q$ = 0.1. • The claim size follows a Gamma distribution with $\alpha$ = 0.8 and $\theta$ = 1. • The number of claims and the claim sizes are independent. • The full credibility standard has been selected so that actual claim costs will be within 10% of expected claim costs 90% of the time. Using limited fluctuation credibility, determine the expected number of exposures required for full credibility. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 514$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 582$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 970$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 5141$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 5818$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 22 – Estimating Aggregate Claims Both Problems 22-A and 22-B use the following information. You are given the following: • The annual number of claims for a policyholder follows a binomial distribution with mean 0.5 and variance 0.375. • The following is the probability function of the claim size $X$. • $\displaystyle \begin{bmatrix} X=x&\text{ }&P(X=x) \\\text{ }&\text{ }&\text{ } \\ 10&\text{ }&0.35 \\ 20&\text{ }&0.35 \\ 30&\text{ }&0.25 \\ 40&\text{ }&0.05 \end{bmatrix}$ • The number of claims and the claim sizes are independent. ___________________________________________________________________________________ Problem 22-A Calculate the variance of the annual aggregate claim amount for the policyholder. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 30$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 71.5$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 180$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 190$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 230$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 22-B In a certain year, the policyholder has incurred at least one claim and the aggregate claim amount is below 45. Given this information, what is the mean aggregate claim amount for the policyholder? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9.0$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 10.0$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 12.5$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 20.0$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 21.3$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 21 – Working with Aggregate Claims Problem 21-A You are given the following: • The annual number of claims follows a Poisson distribution with mean 800. • The claim size follows a Gamma distribution with $\alpha$ = 5 and $\theta$ = 2. • The number of claims and the claim sizes are independent. Using the normal approximation for the distribution of aggregate claim costs, calculate the probability that the aggregate claim costs will exceed 8350? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.11$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.13$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.15$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.17$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0.20$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 21-B You are given the following: • The annual number of claims follows a geometric distribution with mean 8. • The claim size follows an exponential distribution with mean 5. • The number of claims and the claim sizes are independent. Using the normal approximation for the distribution of aggregate claim costs, calculate the 75th percentile of aggregate claim costs? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 64$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 66$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 68$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 70$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 75$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 20 – Working with Full Credibility Standard Problem 20-A You are given the following: • The annual number of claims generated from a portfolio of insurance policies follows a Poisson distribution. • The claim size is modeled by the random variable $Y=X^2$ where $X$ has an exponential distribution with mean 2. • The number of claims and the claim sizes are independent. • The full credibility standard has been selected so that actual claim costs will be within 5% of expected claim costs 95% of the time. Using limited fluctuation credibility, determine the expected number of claims required for full credibility? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3073$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4610$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 6147$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 7684$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9220$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 20-B You are given the following: • The annual number of claims generated from a portfolio of insurance policies follows a Poisson distribution. • The claim size is modeled by the random variable $Y=4 X^2+32$ where $X$ has an exponential distribution with mean 2. • The number of claims and the claim sizes are independent. • The full credibility standard has been selected so that actual claim costs will be within 5% of expected claim costs 95% of the time. Using limited fluctuation credibility, determine the expected number of claims required for full credibility? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2017$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3073$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3457$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4150$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9220$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 16 – Another Poisson-Gamma Problem Both Problems 16-A and 16-B use the following information. A portfolio consists of independent risks divided into two classes. Sixty percent of the risks are in Class 1 and forty percent are in Class 2. • The annual number of claims for a single risk in Class 1 follows a Poisson distribution with mean 1. • The claim size follows a Gamma distribution with mean 1.6 and variance 1.28. • The number of claims and the claim sizes are independent • The annual number of claims for a single risk in Class 2 follows a Poisson distribution with mean 2.6. • The claim size follows a Gamma distribution with mean 2.5 and variance 3.125. • The number of claims and the claim sizes are independent A risk is randomly selected from this portfolio. According to the records of the insurer, there are 4 claims for this risk in the amounts 2, 3, 5 and 5 within the last 3 years. ___________________________________________________________________________________ Problem 16-A Determine the Buhlmann credibility estimate for total claim costs for this risk in the next year. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3.7$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3.7$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4.4$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4.5$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 5.0$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 16-B Determine the Buhlmann credibility estimate for the number of claims for this risk in the next year. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.33$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.35$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.46$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.48$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.64$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 15 – Examples of Frequency-Severity Models Problem 15-A You are given the following: • The annual number of claims generated for a single risk follows a Poisson distribution with mean $\theta$. • The claim size follows a uniform distribution on $(0,10 \theta)$. • The risk parameter $\theta$ is a random variable with density function $\displaystyle \pi(\theta)=\frac{1}{2} \ \theta$ where $0<\theta<2$. • Given $\theta$, the number of claims and the claim sizes are independent. According to the records of the insurer, there are 4 claims in the amounts 5, 5, 15 and 20 within the last 5 years. Determine the Buhlmann credibility estimate for total claim costs in the next year. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9.39$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9.61$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 9.69$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 10.25$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 10.69$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 15-B You are given the following: • The annual number of claims generated for a single risk follows a Poisson distribution with mean $\theta$. • The claim size follows a uniform distribution on $(0,100 \theta)$. • The prior distribution of $\theta$ has a uniform distribution on $(0,5)$. • Given $\theta$, the number of claims and the claim sizes are independent. According to the records of the insurer, there are 5 claims in the total amount of 360 within the last 3 years. Determine the Buhlmann credibility estimate for total claim costs in the next year. $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 97.50$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 164.33$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 179.33$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 212.50$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 257.33$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$ ## Exam C Practice Problem 14 – Examples of Limited Fluctuation Credibility Problem 14-A You are given the following: • The annual number of claims generated from a portfolio of insurance policies follows a Poisson distribution. • The claim size follows a uniform distribution on $(0,t)$ where $t$ is unknown. • The number of claims and the claim sizes are independent. Using limited fluctuation credibility, how many expected claims are required to be 95% certain that actual claim costs will be within 5% of the expected claim costs? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1443$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1579$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1936$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1945$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2050$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ Problem 14-B You are given the following: • The annual number of claims generated from a portfolio of insurance policies follows a Poisson distribution. • The claim size follows a distribution with the following moment generating function. • $\displaystyle M(t)=\frac{1}{(1-10t)^4}$ • The number of claims and the claim sizes are independent. What is the least number of expected claims that are required to be 90% certain that actual claim costs will be within 5% of the expected claim costs? $\text{ }$ $\displaystyle (A) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 820$ $\displaystyle (B) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1230$ $\displaystyle (C) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1353$ $\displaystyle (D) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1376$ $\displaystyle (E) \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1396$ ___________________________________________________________________________________ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ $\text{ }$ ___________________________________________________________________________________ ___________________________________________________________________________________ $\copyright \ 2013 \ \ \text{Dan Ma}$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 205, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5108271837234497, "perplexity": 678.1231594812932}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-47/segments/1573496664469.42/warc/CC-MAIN-20191112001515-20191112025515-00261.warc.gz"}
http://en.wikipedia.org/wiki/Peptide_bond	# Peptide bond Peptide bond A peptide bond (amide bond) is a covalent chemical bond formed between two amino acid molecules.[1] ## Synthesis Glycine condensation The condensation of two amino acids to form a peptide bond (red) with expulsion of water (blue) When two amino acids form a dipeptide through a peptide bond it is called condensation. In condensation, two amino acids approach each other, with the acidmoiety of one coming near the amino moiety of the other. One loses a hydrogen and oxygen from its carboxyl group (COOH) and the other loses a hydrogen from its amino group (NH2). This reaction produces a molecule of water (H2O) and two amino acids joined by a peptide bond (-CO-NH-). The two joined amino acids are called a dipeptide. The peptide bond is synthesized when the carboxyl group of one amino acid molecule reacts with the amino group of the other amino acid molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis reaction (also known as a condensation reaction). The formation of the peptide bond consumes energy, which, in living systems, is derived from ATP.[2] Polypeptides and proteins are chains of amino acids held together by peptide bonds. Living organisms employ enzymes to produce polypeptides, and ribosomes to produce proteins. Peptides are synthesized by specific enzymes. For example, the tripeptide glutathione is synthesized in two steps from free amino acids, by two enzymes: gamma-glutamylcysteine synthetase and glutathione synthetase.[3][4] A peptide bond can be broken by hydrolysis (the adding of water). In the presence of water they will break down and release 8–16 kilojoule/mol (2–4 kcal/mol) [5] of free energy. This process is extremely slow (up to 1000 years). In living organisms, the process is catalyzed by enzymes. ## Spectra The wavelength of absorbance for a peptide bond is 190–230 nm[6] (which makes it particularly susceptible to UV radiation). Figure 1: Dehydration synthesis (condensation) reaction forming an amide ## Cis/trans isomers of the peptide group Significant delocalisation of the lone pair of electrons on the nitrogen atom gives the group a partial double bond character. The partial double bond renders the amide group planar, occurring in either the cis or trans isomers. In the unfolded state of proteins, the peptide groups are free to isomerize and adopt both isomers; however, in the folded state, only a single isomer is adopted at each position (with rare exceptions). The trans form is preferred overwhelmingly in most peptide bonds (roughly 1000:1 ratio in trans:cis populations). However, X-Pro peptide groups tend to have a roughly 3:1 ratio, presumably because the symmetry between the $\mathrm{C^{\alpha}}$ and $\mathrm{C^{\delta}}$ atoms of proline makes the cis and trans isomers nearly equal in energy (See figure, below). Isomerization of an X-Pro peptide bond. Cis and trans isomers are at far left and far right, respectively, separated by the transition states. The dihedral angle associated with the peptide group (defined by the four atoms $C^{\alpha}-C^{\prime}-N-C^{\alpha}$) is denoted $\omega$; $\omega=0^{\circ}$ for the cis isomer and $\omega=180^{\circ}$ for the trans isomer. Amide groups can isomerize about the C-N bond between the cis and trans forms, albeit slowly ($\tau \sim$20 seconds at room temperature). The transition states $\omega= \pm 90^{\circ}$ requires that the partial double bond be broken, so that the activation energy is roughly 80 kilojoule/mol (20 kcal/mol) (See Figure below). However, the activation energy can be lowered (and the isomerization catalyzed) by changes that favor the single-bonded form, such as placing the peptide group in a hydrophobic environment or donating a hydrogen bond to the nitrogen atom of an X-Pro peptide group. Both of these mechanisms for lowering the activation energy have been observed in peptidyl prolyl isomerases (PPIases), which are naturally occurring enzymes that catalyze the cis-trans isomerization of X-Pro peptide bonds. Conformational protein folding is usually much faster (typically 10–100 ms) than cis-trans isomerization (10–100 s). A nonnative isomer of some peptide groups can disrupt the conformational folding significantly, either slowing it or preventing it from even occurring until the native isomer is reached. However, not all peptide groups have the same effect on folding; nonnative isomers of other peptide groups may not affect folding at all. ## Chemical reactions Due to its resonance stabilization, the peptide bond is relatively unreactive under physiological conditions, even less than similar compounds such as esters. Nevertheless, peptide bonds can undergo chemical reactions, usually through an attack of an electronegative atom on the carbonyl carbon, breaking the carbonyl double bond and forming a tetrahedral intermediate. This is the pathway followed in proteolysis and, more generally, in N-O acyl exchange reactions such as those of inteins. When the functional group attacking the peptide bond is a thiol, hydroxyl or amine, the resulting molecule may be called a cyclol or, more specifically, a thiacyclol, an oxacyclol or an azacyclol, respectively. ## References 1. ^ Walker, CBE, FRSE, Peter M. B., ed. (1990) [1988]. Cambridge Dictionary of Science and Technology (reprint ed.). Edinburgh: Press Syndicate of the University of Cambridge. p. 658. ISBN 0521394414. 2. ^ Watson, James; Hopkins, Nancy; Roberts, Jeffrey; Agetsinger Steitz, Joan; Weiner, Alan (1987) [1965]. Molecualar Biology of the Gene (hardcover) (Fourth ed.). Menlo Park, CA: The Benjamin/Cummings Publishing Company, Inc. p. 168. ISBN 0805396144. 3. ^ Wu G, Fang YZ, Yang S, Lupton JR, Turner ND (March 2004). "Glutathione metabolism and its implications for health". The Journal of Nutrition 134 (3): 489–92. PMID 14988435. 4. ^ Meister A (November 1988). "Glutathione metabolism and its selective modification". The Journal of Biological Chemistry 263 (33): 17205–8. PMID 3053703. 5. ^ Martin RB. (1998) "Free energies and equilibria of peptide bond hydrolysis and formation", Biopolymers, 45, 351–353. 6. ^ Goldfarb AR et al. (1951) "The Ultraviolet Absorption Spectra of Proteins", J. Biological Chem., 193, 397–404.(http://www.jbc.org/content/193/1/397.long) • Pauling L. (1960) The Nature of the Chemical Bond, 3rd. ed., Cornell University Press. ISBN 0-8014-0333-2 • Stein RL. (1993) "Mechanism of Enzymatic and Nonenzymatic Prolyl cis-trans Isomerization", Adv. Protein Chem., 44, 1–24. • Schmid FX, Mayr LM, Mücke M and Schönbrunner ER. (1993) "Prolyl Isomerases: Role in Protein Folding", Adv. Protein Chem., 44, 25–66. • Fischer G. (1993) "Peptidyl-Prolyl cis/trans Isomerases and Their Effectors", Angew. Chem. Int. Ed. Engl., 33, 1415–1436.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 8, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8002641797065735, "perplexity": 10112.65394742636}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-49/segments/1416931006064.45/warc/CC-MAIN-20141125155646-00214-ip-10-235-23-156.ec2.internal.warc.gz"}
http://mathhelpforum.com/differential-geometry/105552-epsilon-delta-proof.html	# Math Help - Epsilon-Delta Proof 1. ## Epsilon-Delta Proof Q. Xa is a convergent sequence in R^n where Xa->X as a-> infinity. Use epsilon-delta proof to prove that, in two possibly cases, BXa -> BX as a-> infinity (where B is in R). I tried using the Squeeze Theorem. (Since Xa-X -> 0 as a -> infinity, B(Xa-X) -> 0 as a -> infinity). But don't know how there are two cases and whether this proof can be expressed as epsilon-delta proof. Any help would be greatly appreciated. Thanks. 2. Originally Posted by 6DOM Q. Xa is a convergent sequence in R^n where Xa->X as a-> infinity. Use epsilon-delta proof to prove that, in two possibly cases, BXa -> BX as a-> infinity (where B is in R). I tried using the Squeeze Theorem. (Since Xa-X -> 0 as a -> infinity, B(Xa-X) -> 0 as a -> infinity). But don't know how there are two cases and whether this proof can be expressed as epsilon-delta proof. Any help would be greatly appreciated. Thanks. Since $x_a \to x$ as $a \to \infty$ This means that for every $\epsilon > 0$ there is a $N \in \mathbb{N}$ such that for all $a > N$ $\|x_a-x\| < \epsilon$ Since this is true for every epsilon set $\epsilon ' =\frac{\epsilon}{B}$ and pick a new $N_1 \in \mathbb{N}$ such that when $a > N_1 \implies$ $\|x_a-x\|< \epsilon '$ Now for any $a> N_1$ $\|Bx_a-Bx\|=\|B\|\|x_a-x\|<\|B\|\epsilon ' =\|B\|\frac{\epsilon}{B}=\epsilon$ 3. Thanks! So would the other case be when B is 0? 4. I suppose the cases are when $B=0$ and when $B \neq 0$. The first one is trivial for the second, let $\epsilon$ and $\delta$ be such that if $a> \delta$ then $\Vert x_a - x \Vert < \frac{ \epsilon }{ \vert B \vert }$ (this can be done since $x_a$ converges and $B$ is a constant) then if $a> \delta$ $\Vert Bx_a - Bx \Vert < \epsilon$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 22, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9820438027381897, "perplexity": 527.3929885284253}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1419447548525.16/warc/CC-MAIN-20141224185908-00070-ip-10-231-17-201.ec2.internal.warc.gz"}
https://www.pcb-3d.com/tutorials/dc-motors-voltage-current-speed-power-losses-and-torque-relationships/	# DC Motors – current, voltage, speed, power, losses and torque relationships This article presents basic physical sizes of DC motor with permanent magnet on the stator. This type of motor is very suitable for driving autonomous robots. A main power of the robot is a battery (DC voltage), as well as the power of these engines. In this article, a RE 35 motor with a GP 32 C reducer with a transmission ratio of 1: 14 and a 1: 33 designed and manufactured by MAXON was used as an example. # How is torque related to current? Image 1. Relationship between torque and armature current for the MAXON RE35 Image 1. shows dependence of the armature current from the engine torque for the MAXON RE35 when the armature winding voltage is 12V. The increase in the torque on the motor shaft results in the linear increase in the armature current. It is also shown in the equation (8) from the previous tutorial. The current function I, depending on the torque M, shows that more current flowing through the motor will produce a higher torque. Part of the diagram that is painted in yellow is the area in which the engine is not allowed to operate for a long time (short term operation). # How is torque related to speed? Image 2. Relationship between speed and torque for a MAXON RE35 For each DC motor, a function of speed n can be plotted, depending on the torque M (mechanical engine characteristics). Image 2 shows the dependence of the speed n on the torque M at a constant voltage of 12V. It can be noted that the speed decreases linearly when the torque increases. To draw the curve, two endpoints are used. The first point is when the torque is zero. The second point is when the speed is zero. The image shows that the armature speed is 405 rpm (rotation per minute) when the torque is zero. The torque is 7050 mNm when the speed is zero. This is not presented in the Image 2. If the armature motor voltage is changed, speed and torque also proportionally change. The relation between the speed without load (n0) and armature voltage (U) is given in the following equation: The mechanical power at the output is derived from the input electrical power and power losses (Joule losses) in the motor according to the equation (12). If we use the equations (8) (9) from our previous tutorial and (11) we can calculate output mechanical power with equation (12). Legend: Pel – input electrical power Pj – Power losses in motor Pmeh – output mechanical power n – speed R – armature resistance I – armature current Using the equation (8) and integrating the values for input electrical power and power losses into equation (12), we obtain velocity expressed via the torque: The mechanical output power is calculated over the speed n and torque M according to the following equation (14): # How is mechanical output power related to the torque? Figure 3 shows how the mechanical output power depends on the torque for the MAXON RE35 DC motor. The curve is plotted when applied voltage is 12V and ambient temperature is 25 Celsius degrees. Figure 3. Relation between the mechanical output power and the torque for the MAXON RE35 # How is coefficient of efficiency related to the torque? The coefficient of efficiency describes the relationship between the mechanical power obtained at the output and the electric power applied to the motor input connections. Dependence of the coefficient of efficiency on the torque for the MAXON RE35 is given in Figure 4. Figure 4. Relation between the coefficient of efficiency and the torque for the MAXON RE35 The expression for the coefficient of efficiency is given in the following formula (15): # How is armature resistance related to torque? Figure 5. Relation between the armature resistance and the torque for the MAXON RE35 Dependence of the armature resistance on the torque for the DC motor MAXON RE35 is given in Figure 5. # How is winding temperature related to torque? Figure 6. Relation between the coil temperature and the torque for the MAXON RE35 Dependence of the armature winding temperature on the torque for the MAXON RE35 is given in Figure 6. Usually, encoder is used for measuring speed and position of motor shaft. More about basic operation principle of an encoder, you can find in our tutorial “Optical digital incremental encoder“.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8752362728118896, "perplexity": 1109.5196204372062}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141184870.26/warc/CC-MAIN-20201125213038-20201126003038-00279.warc.gz"}
https://science.sciencemag.org/content/313/5784/233.abstract	Report # Biomineralization of Gold: Biofilms on Bacterioform Gold See allHide authors and affiliations Science 14 Jul 2006: Vol. 313, Issue 5784, pp. 233-236 DOI: 10.1126/science.1125878 ## Abstract Bacterial biofilms are associated with secondary gold grains from two sites in Australia. 16S ribosomal DNA clones of the genus Ralstonia that bear 99% similarity to the bacterium Ralstonia metallidurans—shown to precipitate gold from aqueous gold(III) tetrachloride—were present on all DNA-positive gold grains but were not detected in the surrounding soils. These results provide evidence for the bacterial contribution to the authigenic formation of secondary bacterioform gold grains and nuggets. View Full Text	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8238746523857117, "perplexity": 24840.86820762818}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623487636559.57/warc/CC-MAIN-20210618104405-20210618134405-00047.warc.gz"}
https://blog.metatheorem.org/2018/07/24/Linear-Categories-A-Folklore-Simplification.html	## Linear Categories: A Folklore Simplification Published: 24 July 2018 Recently, I read this paper. The authors use a simplified definition of a linear category, but without proof that their definition is really the same. So I emailed them about it, and started a nice conversion with Damiano Mazza, Marco Gaboardi, and Flavien Breuvart. Then at FLOC 2018 this year I got the opportunity to meet Damiano Mazza, Marco Gaboardi, and a few others for lunch. I learned from Damiano that that their simplification to the definition of linear categories is correct, but this simplification seems to be folklore. So in this post I am going to write out this simplification, and prove that it is equivalent to the original definition of a linear category. ## Linear Categories Linear categories are one of the first sound and complete categorical models of intuitionistic linear logic proposed in Gavin Bierman’s thesis. He shows that the linear exponential, $!A$, can be modeled as a symmetric monoidal comonad. His original definition (Definition 35 on p. 140) is as follows. A linear category, $\cat{C}$, consists of the following structure: 1. A symmetric monoidal category, $\cat{C}$, with finite products and coproducts, 2. A symmetric monoidal comonad $(!,\varepsilon, \delta, \m_{A,B}, \m_I)$ such that a. For every free $!$-coalgebra $(!A,\delta_A)$ there are two distinguished monoidal natural transformations with components: • (Weakening) $\w_A : !A \mto I$ • (Contraction) $\c_A : !A \to !A \otimes !A$ which form a commutative comonad and are coalgebra morphisms. b. Whenever $f : (!A,\delta_A) \mto (!B,\delta_B)$ is a coalgebra morphism between free coalgebras, then it is also a comonoid morphism. There is a lot packed into this definition, but we will expanded it in the next section. ## Linear Categories Simplified Essentially, the simplification amounts to realizing that part b can be proven from the previous parts of the definition of a linear category, but with an additional assumption that is simpler than part b. The expanded simplified definition is as follows. A linear category, $\cat{A}$, consists of the following structure: 1. A is a symmetric monoidal category $(\mathcal{A},\otimes,I,\lambda,\rho,\alpha,\beta)$, 2. A linear exponential comonad, $(!_{-},\delta,\varepsilon)$, which has the following structure: • The endofunctor $! : \mathcal{A} \mto \mathcal{A}$ forms comonad on $\cat{A}$. That is, there are two natural transformations $\delta : ! A \mto !! A$ and $\varepsilon : !A \mto A$ that make the following diagrams commute: • Four natural transformations: • (Monoidal Map) $\m_{A,B} : ! A \otimes ! B \mto ! (A \otimes B)$ • (Monoidal Unit Map) $\m_I : I \mto ! I$ • (Contraction) $\c : !A \mto !A \otimes !A$ • (Weakening) $\w : ! A \mto I$ • The functor $! : \mathcal{A} \mto \mathcal{A}$ is symmetric monoidal. That is, the following diagrams must commute: • The functor $! : \cat{A} \mto \cat{A}$ is a symmetric monoidal comonad. That is, the following diagrams must commute: • Weakening must satisfy the following diagrams: • Contraction must satisfy the following diagrams: • Weakening and contraction form a commutative comonoid. That is, the following diagrams commute: • Weakening and contraction are coalgebra morphisms. That is, the following diagrams must commute: • $\delta_A : !A \mto !!A$ is a comonoid morphism between the comonoids $(!A,\w,\c)$ and $(!!A,\w,\c)$. That is, the following diagrams must commute: All of the structure in the previous definition except for the last bullet corresponds to part 1 and part 2.a of the original definition of a linear category. The last bullet is a simplification of part 2.b. We now show that we can prove part 2.b from the assumptions in this simplified definition. Whenever $f : (!A,\delta_A) \mto (!B,\delta_B)$ is a coalgebra morphism between free coalgebras, then it is also a comonoid morphism. Suppose $f : (!A,\delta_A) \mto (!B,\delta_B)$ is a coalgebra morphism between free coalgebras. This assumption amounts to assuming the following diagram commutes: It suffices to show that $f : (!A,\delta_A) \mto (!B,\delta_B)$ is also a comonoid morphism. Hence, we must show that the following diagrams commute: The left diagram commutes, because the following expanded one does: Diagrams $(1)$ and $(4)$ commute because $\delta$ is a comonoid morphism, diagram $(2)$ commutes because $f$ is assumed to be a coalgebra morphism, and diagram $(3)$ commutes by naturality of $\w$. Note that we have numbered the previous diagram in the order of the necessary replacements needed when doing the same proof equationally, and we do the same for the next diagram. This should make it easier to reconstruct the proof. The diagram for contraction commutes (the diagram on the right above), because the following expanded one does: Diagram $(3)$ commutes because $f$ is assumed to be a coalgebra morphism, diagram $(4)$ commutes by naturality of $\c$, diagram $(5)$ commutes by naturality of $\m$, and diagram $(6)$ commutes by naturality of $\varepsilon$. Diagrams $(1)$ and $(8)$ commute, because the following one does: The left triangle commutes, because $! : \cat{A} \mto \cat{A}$ is a comonad, and the bottom diagram commutes by naturality of $\varepsilon$. Finally, diagrams $(2)$ and $(7)$ do not actually commute, but are parallel morphisms whose cofork is $\delta$. That is, the following diagram commutes: The left diagram commutes because $\delta : !X \mto !!X$ is a comonoid morphism, and the right diagram commutes because weakening and contraction are coalgebra morphisms. Therefore, the original diagram above corresponds to the following equational proof: ## Conclusion This was a really fun proof, but not at all obvious. Folklore results hinder scientific progress, and hinder new comers from progressing in our field. We need to be writing down these types of results so others do not have to! This is the point of research after all. If anyone knows of a paper that writes this proof down, then I would like to know about it so I can cite it in future work. I will update this post with any citations I can find. Updates: Jean-Simon Lemay has communicated to Damiano that this first appeared in a paper by Cocket, Seely, and Blute, but I have not had time to dig through their papers to get the precise citation yet.	{"extraction_info": {"found_math": true, "script_math_tex": 51, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9748095273971558, "perplexity": 542.4931693519567}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583510969.31/warc/CC-MAIN-20181017023458-20181017044958-00405.warc.gz"}
https://electronics.stackexchange.com/questions/158/how-would-i-get-a-full-range-voltage-reading-from-a-pressure-sensor	# How would I get a full range voltage reading from a pressure sensor? I am making an application using the DIY Force Sensitive Resistor (FSR) taken from this instructable. The resistance of this sensor typycally ranges from 20kOhm when at rest to 9kOhm when pressed. How would I convert these resistance values to a signal where 0v corresponds to the rest condition and 5v corresponds to the "pressed" condition so that I can read it with an Arduino? You want a signal range from 0V to 5V. Don't we all :-)? Let's go for a different approach and see where that gets us. Starting point: cheapest and most simple solution. That would be a series resistor to create a voltage divider. That's the absolute minimum. I've noticed that people don't give that resistor much thought, the just pick a nice round value like 10k$\Omega$. But I found that there's an optimal value for this. The curve shows the voltage difference between the minimum and maximum reading (9k$\Omega$ and 20k$\Omega$ resp.) as a function of the series resistor (in k$\Omega$). See, it indeed has a maximum. That's easy to find if you remember that $\left(\dfrac{f(x)}{g(x)}\right)' = \dfrac{f'(x)\cdot g(x) - f(x) \cdot g'(x)}{g^2(x)}$ The difference $V_{MAX}$- $V_{MIN}$ has an extremum for $\dfrac{d}{d R_X} \left(\dfrac{R_{MAX}}{R_{MAX} + R_X} - \dfrac{R_{MIN}}{R_{MIN} + R_X}\right) = 0$ Solving for $R_X$ gives $R_X = \sqrt{R_{MIN} \cdot R_{MAX}}$ A beauty! So in our case the series resistor will be 13.42k$\Omega$, you can check this on the graph. Placing the resistors between 0V and +5V this will give us an output range of [2V, 3V]. That's the maximum range you can get with 1 resistor(). Is it enough? The Arduino has a 10-bit ADC, so this range will give you a range of 200 discrete levels. That should give a sufficient accuracy for a DIY sensor. So no other components like opamps needed. () The accepted answer gives a 1.9V range, but it has the wrong equations. It's impossible to get a higher range than 1V with 1 resistor and only a +5V supply. • +1. This should get more upvotes. Everybody needs a resistor divider for a variable resistor every now and then, and then why not use the optimum range instead of that silly 10k series resistor? – Federico Russo Jun 7 '12 at 7:38 You need a negative voltage to be able to make a resistor voltage divider going to 0V. I'll assume you have +5V and -5V available. Place your variable resistor $R_X$ between +5V and GND. Now you need to find the value for a pull-down resistor between GND and -5V. Now that's easy; you want 0V out when the variable resistor is 20k$\Omega$, so the pull-down also has to be 20k$\Omega$ because the whole thing is symmetrical. Next we have to find out what the output voltage of the divider will be when $R_X$ is 9k$\Omega$. We note that the current through $R_X$ is the same current as the current through the pull-down resistor, so $\dfrac{5V - V_O}{9k\Omega} = \dfrac{V_O - (-5V)}{20k\Omega}$ Working this out gives us $V_O = 1.9V$. Now all that remains to be done is scale the 0V..1.9V to 0V..5V. For this we use an RRIO (Rail-to-Rail I/O) opamp as a non-inverting amplifier If you select $R1 = 18k\Omega$ and $R2 = 47k\Omega$ you'll get an output voltage range of 0V..5V for $R_X$ of 20k$\Omega$..9k$\Omega$. I think the simplest way would be a voltage divider that gives you 5V at 9k and decreases as the resistance increases. You can play with various resistor combinations in this voltage divider calculator. It's going to be a linear progression, however. • You can't make a divider that gives you 5V if all you have is 5V. – Federico Russo Jun 6 '12 at 11:55	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.651914119720459, "perplexity": 1084.0201865458682}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-18/segments/1555578747424.89/warc/CC-MAIN-20190426013652-20190426035652-00528.warc.gz"}
https://cstheory.stackexchange.com/users/44267/ghosts-in-the-code	253 reputation 1 8 ## ghosts_in_the_code $(function() {$(".js-rank-badge").addSpinner().load("/users/rank?userId=44267"); }); Last updated: 9 April 2016, after 3 Nov 2015 A few things to know about me: 1. I'm a school student. 2. I sometimes write posts in a massive hurry, and often make careless mistakes. 3. I have two objectives on this site: • Earn as much rep as possible. I guess this objective has faded with time. 4. I love this site (SE). 5. I'm waiting for the day this site makes a popular site worldwide, just like Wikipedia. I'm also waiting for the day 'Puzzling' becomes a full-fledged site (It's currently in Beta). It seems that this will happen soon! 6. I offer bounties quite often. As of today (3 Nov 2015), I have 2015 2370 rep in my account and 1250 1750 rep in offered bounties on Puzzling SE. What I am known for: Simple questions which have no solution till date: Check out the list at http://meta.puzzling.stackexchange.com/questions/4399/list-of-bounties-with-no-deadlines It is updated and more reliable. On Puzzling SE (I can promise a minimum 250 rep bounty for solving any of these five, or even improving on the current best score) On Math SE Some things I would like: (Please ignore.) 1. Total rep = Earned rep, not Total rep = Earned rep - Spent rep. Spent rep should be accounted separately so that the bounties you put equal the rep you have earned. For example, if you have earned 2000 and spent 400, your total rep is still 2000 and your leftover spending rep is 1600. 2. I'd like the process of creating a new site (Private and Public Beta) to be a bit faster. I can't understand one good reason why Puzzling SE should be called a 'beta' site. Does 'beta' mean there is something missing? 3. I would like the question ban on me on Meta SE to be removed. I know SE doesn't handle such requests manually, but I do believe I deserve another chance, after all, it's been over a year. Moreover, I have asked more good questions than bad on the site-specific metas. 0 6 questions ~921 people reached • New Delhi • Member for 3 years, 9 months • 11 profile views • Last seen Aug 26 at 8:44 Score 0 Posts 2 Posts % 33 Score 0 Posts 2 Score 0 Posts 1 Score 0 Posts 1 Score 0 Posts 1 Score 0 Posts 1 1 8	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.20621244609355927, "perplexity": 5044.840541164385}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141187753.32/warc/CC-MAIN-20201126084625-20201126114625-00021.warc.gz"}
https://www.biodiversity-science.net/EN/10.3724/SP.J.1003.2010.233	Biodiv Sci ›› 2010, Vol. 18 ›› Issue (3): 233-240. • Special Issue • ### Genetic diversity in six natural populations of Betula luminifera from southern China Junhong Zhang1, Huahong Huang1, Zaikang Tong1,*(), Longjun Cheng1, Yuelong Liang2, Yiliang Chen3 1. 1 Zhejiang Forestry University, Lin'an, Zhejiang 311300 2 Jiulianshan National Forestry Park, Longnan, Jiangxi 341701 3 Qingyuan Forestry Farm of Lishui City in Zhejiang Province, Qingyuan, Zhejiang 323800 • Received:2009-11-11 Accepted:2010-04-24 Online:2010-05-20 Published:2012-02-08 • Contact: Zaikang Tong Abstract: Betula luminifera, a precious timber species in southern mountain areas of China, can be found only in natural reserves because of over harvesting. We examined the genetic diversity and genetic structure of six natural populations of B. luminifera distributed in Zhejiang, Fujian, Jiangxi, Guangxi, and Guizhou using AFLP markers. A total of 323 polymorphic loci were amplified and 355 alleles were detected using nine pairs of primers. Percentage of polymorphism loci (PPL) ranged 93.20-98.60% and Nei’s gene diversity (hj) ranged 0.3143-0.3645, suggesting a high genetic diversity in natural populations of B. luminifera. At the species level, the total genetic diversity (Ht) was 0.3616. High gene flow (Nm = 3.5962) was detected among populations, and the genetic differentiation coefficient was 0.0650. AMOVA analysis showed that genetic variation among the populations accounted for 11.49% of the total. Genetic distance was the largest (0.0665) between Zhejiang (LA) and Guizhou (XW) populations and the smallest (0.0173) between Jiangxi (LN) and Guangxi (LS) populations, indicating that LN and LS populations may originate from the same ancestor. Mantel test revealed that genetic distance was not significantly related to geographical distance (r = 0.423,P = 0.113) but was significantly relative to average temperature difference of each location (r = 0.449, P = 0.017). In combination with on-site investigation, we conclude that the present status of genetic diversity and genetic structure of natural populations of B. luminifera was strongly affected by harvesting and habitat fragmentation. We propose some suggestions on its conservation.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.16505084931850433, "perplexity": 24993.504086743047}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656104668059.88/warc/CC-MAIN-20220706060502-20220706090502-00487.warc.gz"}
https://crypto.stackexchange.com/questions/34601/how-to-prove-hardness-of-approximate-gcd-problem	# How to prove hardness of approximate-GCD problem? I am trying to prove the security of my system using the hardness assumption of the approximate-GCD problem using contradiction, i.e. If the attacker is able to break in our scheme, then attacker would be able to solve the approximate-GCD problem. I am stuck at the point where I proved that the complexity is O(2^rho) using brute-force approach. How shall I proceed? Is there any concrete complexity measure which can be used as to prove the contradiction? • Assume there is a crack for your scheme, and now show that by inputting careful values to this crack program, you obtain a solution to AGCD, or at least get something easily converted into a solution. This is the formula for a reductionist security proof. You just show that you can actually use any crack to compute the hard problem easily. Even if the crack works in an unexpected way. – MickLH Jan 25 '17 at 20:57 I am stuck at the point where I proved that the complexity is $O(2^\rho)$ using brute-force approach. How shall I proceed?	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9459689855575562, "perplexity": 329.28393101887}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579251705142.94/warc/CC-MAIN-20200127174507-20200127204507-00409.warc.gz"}
http://physics.aps.org/story/v10/st18	# Focus: Nobel Focus: Neutrino and X-ray Vision Published October 16, 2002 \| Phys. Rev. Focus 10, 18 (2002) \| DOI: 10.1103/PhysRevFocus.10.18 #### Observation of a neutrino burst from the supernova SN1987A K. Hirata, T. Kajita, M. Koshiba, M. Nakahata, Y. Oyama, N. Sato, A. Suzuki, M. Takita, Y. Totsuka, T. Kifune, T. Suda, K. Takahashi, T. Tanimori, K. Miyano, M. Yamada, E. W. Beier, L. R. Feldscher, S. B. Kim, A. K. Mann, F. M. Newcomer, R. Van, W. Zhang, and B. G. Cortez Published April 6, 1987 #### Search for Neutrinos from the Sun Raymond Davis, Jr., Don S. Harmer, and Kenneth C. Hoffman Published May 20, 1968 #### Evidence for x Rays From Sources Outside the Solar System Riccardo Giacconi, Herbert Gursky, Frank R. Paolini, and Bruno B. Rossi Published December 1, 1962 This year’s Nobel Prize in Physics went to three experimentalists who opened the window on cosmic neutrinos and x rays. Raymond Davis of the University of Pennsylvania in Philadelphia and Masatoshi Koshiba of the University of Tokyo shared half of the Prize for detecting neutrinos emitted from sources beyond Earth, while Riccardo Giacconi of Associated Universities, Inc., in Washington, DC, claimed the other half for the discovery of cosmic x rays. Their pioneering work was documented in PRL. The neutrino, a product of certain nuclear decay reactions, is maddeningly hard to detect, even from the nearby Sun. In the early 1950s, at Brookhaven National Laboratory in Upton, New York, Raymond Davis developed a system for capturing the radioactive argon atoms produced when neutrinos collide with molecules containing chlorine and carbon. He filled a tank in the Homestake Gold Mine in South Dakota with over 600 tons of the dry-cleaning fluid perchloroethylene $(C2Cl4),$ bubbling helium through it to remove the argon produced by neutrinos. The amount of argon then gave a measure of the number of neutrinos that hit the tank. In 1968, Davis and his collaborators reported their detection of solar neutrinos, the first direct evidence for the nuclear reactions that power the sun. The solar neutrino flux they measured was several times lower than the first calculations by John Bahcall, now at the Institute for Advanced Study in Princeton, New Jersey, predicted–a discrepancy dubbed the “solar neutrino problem.” Inspired by Davis’s results, Masatoshi Koshiba converted his underground Kamiokande experiment from a proton decay detector to a neutrino spotter in 1986. Koshiba and his colleagues had placed photomultiplier tubes, which detect single photons, around 2,000 tons of water to see the Cherenkov light that would appear if a proton decayed. Neutrinos bouncing off of electrons would also produce Cherenkov radiation at lower energies, so Koshiba modified the design. Besides confirming the solar neutrino deficit, the experiment detected a neutrino burst from supernova 1987A in the Large Magellanic Cloud, 170,000 light years away. That signal, which was also picked up by another neutrino facility, was the first clear detection of neutrinos from outside the solar system. Davis and Koshiba made extraordinary contributions in part because “solar neutrino experiments have a sensitivity that is not accessible [with neutrinos] from the Earth,” says Bahcall. In 1998, the Super-Kamiokande experiment, also designed by Koshiba, found strong evidence that the solar neutrino problem was a result of neutrinos oscillating among their three flavors, only one of which was detected [1]. The Sudbury Neutrino Observatory in Canada greatly strengthened that conclusion this year [2]. Riccardo Giacconi had a stubborn quarry of his own. The Earth’s upper atmosphere mostly absorbs high energy cosmic x rays, which are intrinsically hard to focus into usable images. In 1962, Giacconi and his group, then at the private company American Science and Engineering, sent up a rocket equipped with Geiger counters to look for solar x rays reflected from the moon. Instead they found a strong cosmic x-ray source, later named Scorpius X-1, and a uniform haze of x rays across space. Scorpius X-1 was a surprise because it produced far more x rays than visible light. Resolution of x-ray signals gradually improved, and the use of satellites increased observation times. Giacconi’s group led the way in space-based observing with UHURU in 1970 and continued with the Einstein Observatory in 1979. The two missions each revolutionized x-ray astronomy, says Fred Lamb of the University of Illinois at Urbana-Champaign. Thousands of x-ray sources are now known, from clouds of hot gas to binary stars and other dense stellar objects, such as black holes. “The ‘62 flight alone, believe me, is worth a Nobel Prize,” says Walter Lewin of the Massachusetts Institute of Technology in Cambridge. Lamb is pleased that this year’s Prize honors astrophysics and astronomy. “It’s great to see this kind of work recognized,” he says. –JR Minkel JR Minkel is a freelance science writer in New York City. ### References 1. Y. Fukuda, et al.,mPhys. Rev. Lett. 81, 1562 (1998) .. 2. Q. R. Ahmed, et al., Phys. Rev. Lett. 89, 011301 (2002);Q. R. Ahmed et al., Phys. Rev. Lett. 89, 011302 (2002).	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 1, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7515900731086731, "perplexity": 3932.66754196395}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-15/segments/1398223202457.0/warc/CC-MAIN-20140423032002-00649-ip-10-147-4-33.ec2.internal.warc.gz"}
https://physics.stackexchange.com/questions/133610/what-is-supersymmetry	# What is supersymmetry? 1. What is supersymmetry? 2. How is it useful in unifying physics? I have heard that supersymmetry states that every fermion is associated with a boson and vice versa. But I don't get hope this can help resolving problems in unifying physics. What is supersymmetry (in a big nutshell)? To explain supersymmetry, let us consider the simplest supersymmetric model which is the Wess-Zumino model with an action, $$S=-\int d^4x \left( \frac{1}{2}\partial^\mu \phi^\star \partial_\mu \phi + i\psi^\dagger \bar{\sigma}^\mu \partial_\mu \psi + \|F\|^2 \right)$$ where $\phi$ is a scalar field, $\psi$ a Majorana spinor field and $F$ is known as an auxiliary field, a pseudo-scalar, which arises due to a subtlety explained later. A supersymmetry is a continuous symmetry relating bosons to fermions and vice versa. Most importantly, for it to be a symmetry of the system, we must require that the Lagrangian changes only up to a total derivative. Naively, we might propose: $$\delta\phi = \epsilon_\alpha \psi^\alpha$$ $$\delta\psi^\alpha = \epsilon^\alpha\phi$$ where we have introduced an infinitesimal parameter $\epsilon^\alpha$ which is required in order to balance the indices on both sides of the transformation. The parameter is fermionic; to deduce the dimensionality, we can do some dimensional analysis. $$[\partial_\mu\phi^\star\partial_\mu\phi] = 4,\; [\partial_\mu] = 1$$ hence $[\phi] = 1$. Similar reasoning for the fermionic field shows $[\psi] = 3/2$, as expected. Now from the transformation, we may deduce the dimension of the arbitrary parameter: $$[\epsilon^\alpha] = [\psi]-[\phi] = 1/2$$ and $[\epsilon_\alpha] = -1/2$. Plugging the transformation in, and deducing $\delta\mathcal{L}$, we will find it does not quite cancel to leave only a total derivative left. After some manipulation, we can find: $$\delta\psi_\alpha = -i(\sigma^\nu\epsilon^\dagger)_\alpha \partial_\nu \phi$$ Now to address the auxiliary field, $F$. If we compute the equations of motion, we find $$\frac{\partial \mathcal{L}}{\partial F} \sim F \quad \frac{\partial \mathcal{L}}{\partial (\partial F)} = 0$$ which implies $F=0$. Although it may seem adding the field has no effect, remember that $F=0$ is only true on-shell. The purpose of $F$ then is actually off-shell, which you will notice balances the required degrees of freedom of the system for consistency. A Historical Note In 1967, Coleman and Mandula published a paper, All Possible Symmetry of the S-Matrix, which aptly presented a theorem restricting S-matrix symmetries. However, a key assumption was A symmetry transformation is said to be an internal symmetry transformation if it commutes with P. This implies that it acts only on particle-type indices, and has no matrix elements between particles of different four-momentum or different spin. A group composed of such transformations is called an internal symmetry group. In other words, the symmetries were bosonic; notice that supersymmetry is in fact fermionic, and hence not subject to the Coleman-Mandula theorem. In some ways, one may attribute the initial development of supersymmetry to a desire to find a loophole in the Coleman-Mandula theorem. Resources • For a simple introduction, see the Beyond the Standard Model course by Professor Veronica Sanz, available here: http://www.perimeterscholars.org/338.html, which includes videos. • For a modern introduction, complete with superfields, supermanifolds and more, see the text String Theory and M-Theory: A Modern Introduction, by Becker, Becker and Schwarz where it is presented in the context of string theory.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9113717079162598, "perplexity": 211.38571522560886}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-35/segments/1566027313889.29/warc/CC-MAIN-20190818124516-20190818150516-00396.warc.gz"}
https://www.scielo.br/j/rsp/a/DmLdYsvnyLLdvfXMSj69Bnn/?lang=en	# ABSTRACT ## OBJECTIVE To analyze Government strategies for reducing prices of antiretroviral medicines for HIV in Brazil. ## METHODS Analysis of Ministry of Health purchases of antiretroviral medicines, from 2005 to 2013. Expenditures and costs of the treatment per year were analyzed and compared to international prices of atazanavir. Price reductions were estimated based on the terms of a voluntary license of patent rights and technology transfer in the Partnership for Productive Development Agreement for atazanavir. ## RESULTS Atazanavir, a patented medicine, represented a significant share of the expenditures on antiretrovirals purchased from the private sector. Prices in Brazil were higher than international references, and no evidence was found of a relationship between purchase volume and price paid by the Ministry of Health. Concerning the latest strategy to reduce prices, involving local production of the 200 mg capsule, the price reduction was greater than the estimated reduction. As for the 300 mg capsule, the amounts paid in the first two years after the Partnership for Productive Development Agreement were close to the estimated values. Prices in nominal values for both dosage forms remained virtually constant between 2011 (the signature of the Partnership for Productive Development Agreement), 2012 and 2013 (after the establishment of the Partnership). ## CONCLUSIONS Price reduction of medicines is complex in limited-competition environments. The use of a Partnership for Productive Development Agreement as a strategy to increase the capacity of local production and to reduce prices raises issues regarding its effectiveness in reducing prices and to overcome patent barriers. Investments in research and development that can stimulate technological accumulation should be considered by the Government to strengthen its bargaining power to negotiate medicines prices under a monopoly situation. Anti-HIV Agents, supply & distribution; Drug Price; Health Care Costs; Intellectual Property; National Drug Policy # RESUMO ## OBJETIVO Analisar as estratégias governamentais para redução de preço de medicamentos antirretrovirais para aids no Brasil. ## MÉTODOS Realizada análise das compras de medicamentos antirretrovirais pelo Ministério da Saúde, de 2005 a 2013. Foram analisados o gasto e o custo do tratamento por ano e comparados com os preços internacionais para o atazanavir. Foram estimadas as reduções com base no contrato da Parceria para Desenvolvimento Produtivo para obtenção de licença voluntária de patente e transferência de tecnologia do atazanavir. O atazanavir teve peso expressivo nos gastos com antirretrovirais adquiridos no setor privado. Os preços praticados no Brasil foram mais altos que aqueles de referência internacional e não houve evidências da relação entre volume de compra e preço pago pelo Ministério da Saúde, por ser medicamento patenteado. Em relação à estratégia mais recente para reduzir preços, envolvendo produção local da cápsula de 200 mg, as reduções foram menores do que as estimadas. Quanto à cápsula de 300 mg, os valores pagos nos dois primeiros anos após a Parceria para Desenvolvimento Produtivo foram próximos aos estimados. Os preços em valores nominais mantiveram-se praticamente constantes entre 2011 (assinatura da Parceria para Desenvolvimento Produtivo), 2012 e 2013 (após estabelecida a Parceria). ## CONCLUSÕES A redução do preço de medicamentos é complexa em ambiente de concorrência limitada. O uso da Parceria para Desenvolvimento Produtivo como método para aumentar a capacidade de produção local e reduzir preços levanta questões em relação à redução efetiva dos preços e ao enfrentamento da barreira patentária. Investimentos em pesquisa e desenvolvimento que possam estimular a acumulação tecnológica devem ser considerados pelo governo para fortalecer seu poder de barganha ao negociar preços de medicamentos em situação de monopólio. Fármacos Anti-HIV, provisão & distribuição; Preço de Medicamento; Custos de Cuidados de Saúde; Propriedade Intelectual; Política Nacional de Medicamentos # INTRODUCTION Since 1996, Brazil ensures free universal access to antiretroviral medicines (ARV) and other medicines necessary for the treatment and control of HIV infection, through the Brazilian Unified Health System (SUS).77. Greco DB, Simão M. Brazilian policy of universal access to AIDS treatment: sustainability challenges and perspectives. AIDS. 2007;21Suppl 4:S37-45. DOI:10.1097/01.aids.0000279705.24428.a3 Over the years, prices, costs and increasing expenditure on medicines under a monopoly situation threaten the financial sustainability of the Brazilian response to the epidemic.77. Greco DB, Simão M. Brazilian policy of universal access to AIDS treatment: sustainability challenges and perspectives. AIDS. 2007;21Suppl 4:S37-45. DOI:10.1097/01.aids.0000279705.24428.a3,1818. Orsi F, Hasenclever L, Fialho B, Tigre P, Coriat B. Intellectual property rights, anti-AIDS policy and generic drugs: lessons from the Brazilian Public Health Program. In: Moatti J-P, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.109-35. (Collection Sciences Sociales et SIDA).,2020. Possas C, Scapini R, Simão M. Sustentabilidade da política brasileira de acesso universal e gratuito aos medicamentos ARV: conquistas e desafios. In: Possas C, Larouzé B, editores. Propriedade intelectual e políticas públicas para o acesso aos antirretrovirais nos países do Sul. Rio de Janeiro: ANRS/ E-Papers; 2013. p.199-219. The expenses of the Ministry of Health (MoH) have increased due to: the increasing number of people living with HIV receiving ART (antiretroviral therapy); the emergence of viral strains resistant to first and second line regimens; and to the incorporation of new ARV.66. Grangeiro A, Teixeira L, Bastos FI, Teixeira P. Sustentabilidade da política de acesso a medicamentos anti-retrovirais no Brasil. Rev Saude Publica. 2006;40 Supl:60-9. DOI:10.1590/S0034-89102006000800009,1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478 The need to migrate to second and third-line therapeutic regimens, due to the emergence of viral resistance, requires the use of more expensive ARV, usually imported and under a monopoly situation.77. Greco DB, Simão M. Brazilian policy of universal access to AIDS treatment: sustainability challenges and perspectives. AIDS. 2007;21Suppl 4:S37-45. DOI:10.1097/01.aids.0000279705.24428.a3 In the current situation, of the implementation of the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS Agreement) of the World Trade Organization (WTO), the newest ARV are under a monopoly situation in Brazil and internationally. This increases the difficulty to negotiate and obtain price reductions.33. D'Almeida C, Hasenclever L, Krikorian G, Sweet C, Coriat B, Orsi F. New antiretroviral treatments and post-2005 TRIPS constraints: first moves towards IP flexibilization in developing countries. In: Coriat B, editor. The political economy of HIV/AIDS in developing countries. Northampton: Edward Elgar Publishing; 2008. p.25-52.,1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478,1818. Orsi F, Hasenclever L, Fialho B, Tigre P, Coriat B. Intellectual property rights, anti-AIDS policy and generic drugs: lessons from the Brazilian Public Health Program. In: Moatti J-P, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.109-35. (Collection Sciences Sociales et SIDA). The ARV medicines under a monopoly situation are those offered by a single supplier, generally because they are subject to patent protection (patent application filed or patent granted in the country). Studies have examined the evolution of the Ministry of Health expenditure on ARV and the determinants of prices in a historical series from 1996 to 2009.6,9-11,16,a a Santos RSL. Sustentabilidade do Programa Nacional de DST/aids: análise da capacidade de oferta e preços dos medicamentos antirretrovirais [dissertation]. Rio de Janeiro (RJ): Instituto de Economia da Universidade Federal do Rio de Janeiro; 2010. For ARV under a monopoly situation their prices reduced initially, but this gain was lost over time. A significant increase of expenditure on patented ARV was observed, which reached 80.0% of MoH resources allocated for the purchase of all ARV in 2004 and 2005.1616. Nunn AS, Fonseca EM, Bastos FI, Gruskin S, Salomon JA. Evolution of antiretroviral drug costs in Brazil in the context of free and universal access to AIDS treatment. PLoS Med. 2007;4(11):e305. DOI:10.1371/journal.pmed.0040305 Medicines that have multiple suppliers are more sensitive to variables such as purchase volumes. The prices of medicines under a monopoly situation are less sensitive to purchase volumes, but are affected when the MoH bargaining power in price negotiations is strengthened by the use of: evidence on production costs; the threat or issuance of a compulsory license, amongst others.1616. Nunn AS, Fonseca EM, Bastos FI, Gruskin S, Salomon JA. Evolution of antiretroviral drug costs in Brazil in the context of free and universal access to AIDS treatment. PLoS Med. 2007;4(11):e305. DOI:10.1371/journal.pmed.0040305 Bargaining power is reduced when the local technological and industrial capacity or the alternatives suppliers do not exist or are limited.99. Lucchini S, Cisse B, Duran S, Cenival M, Comiti C, Gaudry M et al. Decrease in prices of antiretroviral drugs for developing countries: from political "philanthropy" to regulated markets? In: Moatti JP, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.169-211. (Collection Sciences Sociales et SIDA).,1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478,1616. Nunn AS, Fonseca EM, Bastos FI, Gruskin S, Salomon JA. Evolution of antiretroviral drug costs in Brazil in the context of free and universal access to AIDS treatment. PLoS Med. 2007;4(11):e305. DOI:10.1371/journal.pmed.0040305 International initiatives to tackle ARV prices under a monopoly situation were implemented in developing countries in the 2000s. Major donors, such as the Global Fund to Fight AIDS, Tuberculosis and Malaria and the Unitaid, had an important role in market dynamics and price reductions by purchasing large quantities and using market guarantees to stimulate the development of fixed-dose combinations and pediatric formulations.2525. Waning B, Kyle M, Diedrichsen E, Soucy L, Hochstadt J, Barnighausen T et al. Intervening in global markets to improve access to HIV/AIDS treatment: an analisys of international policies and the dynamics of global antiretroviral medicines markets. Global Health. 2010;6:9. DOI:10.1186/1744-8603-6-9 Multinational pharmaceutical companies, in turn, have adopted price discrimination policies ("tiered pricing"), creating categories of price discounts based on criteria established by them, which can include country's level of development and/or the national prevalence of HIV.1313. Moon S, Jambert E, Childs M, Schoen-Angerer T. A win-win solution?: a critical analysis of tiered pricing to improve access to medicines in developing countries. Global Health. 2011;7:39. DOI:10.1186/1744-8603-7-39,2424. Waning B, Kaplan W, King AC, Lawrence DA, Leufkens HG, Fox MP. Global strategies to reduce the price of antiretroviral medicines: evidence from transactional databases. Bull World Health Organ. 2009;87(7):520-8. DOI:10.1590/S0042-96862009000700013 However, the same criteria are not universally adopted by companies, and countries might be eligible to price discounts offered by some companies but not by others. One recent initiative that aims to overcome patent barriers and to encourage the availability of fixed-dose combinations and pediatric formulations is the creation of the Medicines Patent Pool (MPP), which negotiates voluntary licenses with multinational pharmaceutical companies to promote generic competition and reduce prices.b b Medicines Patent Pool [Internet]. About the MPP. [cited 2014 Feb 23]. Available from: http://www.medicinespatentpool.org/about Although these international initiatives show results in the expansion of access to ARV and addressing some high prices, Brazil is excluded from all of them and has had to develop its own strategies. The Brazilian Government's main strategies to reduce ARV prices under a monopoly situation, from 2001 to 2007, included: price negotiation with multinational pharmaceutical companies, with the threat of issuing compulsory licenses, based on estimates of production cost1919. Pinheiro ES, Vasan A, Kim JY, Lee E, Guimier JM, Perriens J. Examining the production costs of antiretroviral drugs. AIDS. 2006;20(13):1745-52. DOI:10.1097/01.aids.0000242821.67001.65 and international reference prices; the challenging of patent applications by a public manufacturer;11. Barroso W. Contribuição ao estudo do subsídio ao exame de pedido de patente no Brasil. In: Corrêa M, Cassier M, organizadores. Aids e saúde pública: contribuições à reflexão sobre uma nova economia política do medicamento no Brasil. Rio de Janeiro: EDUERJ; 2010. p.203-40. the issuance of a compulsory license for importation and subsequent local production of the medicine.1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478,2222. Rodrigues WCV, Soler O. Licença compulsória do efavirenz no Brasil em 2007: contextualização. Rev Panam Salud Publica. 2009;26(6):553-9. DOI:10.1590/S1020-49892009001200012 The study of governmental strategies to ensure access to ARV in a country like Brazil includes understanding the process of technology incorporation in the health system, approaches to ensure availability (regarding the maintenance and expansion of treatment) as well as initiatives for tackling prices of products under a monopoly situation, including efforts for local production. The objective of this study was to analyze Government strategies to reduce the price of antiretroviral medicines for HIV. # METHODS This is a case study based on the medicine atazanavir, which includes the use of a Partnership for Productive Development (PDP). The methodology involved two steps: analysis of the importance of atazanavir for HIV treatment and its share of the MoH budget for ARV, and comparison of the prices paid by the MoH with international reference prices. Purchases of ARV by the MoH from 2005 to 2013 were analyzed using the records of the General Services Administration Integrated System (SIASG). This system contains information on public purchases by the Federal Public Administration, from the private sector. SIASG does not include purchases from public manufacturers. The volume and unit prices of annual purchases were used to estimate the total expenditure on ARV and the proportion represented by atazanavir per year. The final volume per year was expressed as number of treatments. The cost of treatment per patient per year (number of capsules per day × 365 × median price) was also calculated, using as reference the 2008 treatment guideline of the Ministry of Health for antiretroviral therapy in adults. Median prices in Brazilian reais (R$) were adjusted for inflation by the Consumer Price Index (IPCA), using the references provided at the IPEA-data webpage. The variation rates were calculated for prices and volumes, and the correlation coefficient (t-Student's test) for the 200 mg capsule was also calculated.1414. Morettin PA, Bussab WO. Estatística básica. 8.ed. Rio de Janeiro: Saraiva; 2013. Median prices were converted to the average US dollar rate for the year (IPEA-data) for comparison with international prices. International prices used were as published by Doctors without Borders,c c Médecins San Frontières, Access Campaign. Untangling the web of antirretroviral price reductions [internet]. 17.ed. Geneva: MSF; 2014 [cited 2014 Nov 15]. Available from: https://www.msfaccess.org/sites/default/files/MSF_UTW_17th_Edition_4_b.pdf which tracks the lowest prices charged by multinational companies in different countries and by generic alternatives. The analysis of the PDP for local production of atazanavir aimed to deepen the knowledge about a new Government strategy for price reduction. Among the documents reviewed was the ‘Technical Cooperation Agreement for Sublicensing of Patent Exploitation, Technology Transfer (atazanavir) and Provision signed between the Oswaldo Cruz Foundation and Bristol-Myers Squibb Company' (hereinafter referred to as the "Agreement"). The Agreement was obtained through access to information channels and provided by the Brazilian Interdisciplinary Aids Association. The agreement shows an estimate of a 5.0% reduction in the price of atazanavir per year. This percentage was used to estimate the price reduction from 2012. The analysis enabled inferences about the conditions of the technology transfer to be made. # RESULTS In view of total ARV expenditure purchased from the private sector (the majority under a monopoly situation),d d Villardi P. Panorama do status patentário e registro sanitário dos medicamentos antirretrovirais no Brasil: implicações para o acesso e a política industrial no Brasil. Rio de Janeiro (RJ): Associação Brasileira Interdisciplinar de Aids; 2012 [cited 2014 Jun 12]. Available from: http://www.deolhonaspatentes.org.br/media/file/Publica%C3%A7%C3%B5es/Publica%C3%A7%C3%A3o%20Pedro_Final_23OUT.pdf the proportion of expenditure on atazanavir ranged from 28.7% in 2008 to 66.5% in 2010, with percentages below 15.0% in 2007 (6.5%), 2009 (13.4%) and 2012 (13.7%) (Table 1). Table 1 Estimates of annual spending of the Ministry of Health with antiretroviral medicines (ARV) acquired in the private sector and the proportion spent with atazanavir. Brazil, 2005 to 2013. The correlation coefficient for the 200 mg capsule, -0.2108 (p = 0.62), suggests no evidence of correlation between rates of change of volume and rates of change in price (Table 2), during the period. Table 2 Estimates of the volume purchased, median price and cost per patient/year of atazanavir 200 mg, 150 mg and 300 mg. Brazil, 2005 to 2013. The comparison between prices paid in Brazil, and the lowest price offered by Bristol-Myers Squibb (BMS) (discount price) and the generic version, showed that those paid in Brazil are the highest (Figure 1). Figure 1 Comparison of the price paid by the Ministry of Health for the atazanavir 150 mg, 200 mg and 300 mga with discount prices offered by Bristol-Myers Squibb and the prices of the generic version. Brazil, 2005 to 2013. In relation to the latest strategy adopted in Brazil, price reduction estimates of 5.0% per year and actual prices paid for 2012 and 2013 are presented. The price reductions observed for the 200 mg capsule were greater than the estimated reduction of 5.0% (Figure 2). The amounts paid for the 300 mg capsule in the first two years after the PDP were close to the estimated values (Figure 3). Figure 2 Prices paid for atazanavir 200 mg and reduction estimation after signing the Agreement of Partnership for Productive Development. Brazil, 2005 to 2016. Figure 3 Prices paid for atazanavir 300 mg and reduction estimation after signing the Agreement of Partnership for Productive Development. Brazil, 2009 to 2016. Although these values indicate consistency with the estimated reduction, nominal values remained virtually constant between 2011 (signing of the PDP), 2012 and 2013 (operation of PDP). The prices paid in the three years for the 200 mg capsule were R$3.47, R$3.34 and R$3.40, respectively. The prices paid for the 300 mg capsule in the three years were R$5.46, R$5.46 and R\$5.58, respectively. The volume purchased in 2013 increased by more than 31,863 treatments from 2012 (Table 2). # DISCUSSION Atazanavir is a protease inhibitor, used with ritonavir as a booster. Atazanavir has been recommended by the World Health Organization (WHO) for the treatment of HIV since 2006 (Treatment Guidelines for adults and adolescents), included among the second-line regimens. It was included in the WHO Essential Medicines List in 2009 for adults and children, respectively, in the 16th and 2nd editions of the Model List. In Brazil, atazanavir was incorporated in the treatment guidelines of 2003, indicated as one of the options for first-line or as part of second-line treatment. Its adoption in the country was almost simultaneous with the approval of the medicine by the FDA (United States Food and Drug Administration), in June 2003. Between the arrival of the first batches of atazanavir in January 2004 and December 2006, the number of people who used the medicine increased from 6,000 in July 2004 to 25,000 people in 2006.e e Scheffer MC. Aids, tecnologia e acesso sustentável a medicamentos: a incorporação dos antirretrovirais no Sistema Único de Saúde [thesis]. São Paulo (SP): Faculdade de Medicina da Universidade de São Paulo; 2008. The data in Table 1 reflects an estimate of the number of treatments purchased, rather than used, in that year. However, considering that the MoH provides more than 20 ARV, the expenditure on atazanavir is significant. The BMS holds the exclusive right to market atazanavir in Brazil because it is the patent holder of the medicine (effective until 2016), while the MoH is the sole buyer. The use of purchase volumes should be considered as a strategy for price reductions. It would be expected that the larger the purchase volumes, the lower the price paid.1212. Melo LM. Modelos tradicionais de concorrência. In: Kupfer D, Hasenclever L, organizadores. Economia industrial: fundamentos teóricos e práticas no Brasil. 2.ed rev. ampl. Rio de Janeiro: Elsevier; 2013. Cap.1, p.3-14. Based on this assumption, in 1996, the MoH chose to centralize ARV purchases as a strategy to reduce prices and ensure availability.1717. Oliveira MA, Esher A. Acesso universal ao tratamento para as pessoas vivendo com HIV/Aids no Brasil. In: Bermudez JAZ, Oliveira MA, Esher A, organizadores. Acceso a medicamentos: derecho fundamental, papel del Estado. Rio de Janeiro: Fiocruz/OPAS; 2004. p.233-50. However, the correlation coefficient of variation rates, of purchase volumes and prices of 200 mg atazanavir, suggests lack of evidence of correlation (Table 2). Therefore, the monopoly power conferred by the patent undermined the purchasing power of the MoH. The prices of ARV purchased in Brazil between 1998 and 200199. Lucchini S, Cisse B, Duran S, Cenival M, Comiti C, Gaudry M et al. Decrease in prices of antiretroviral drugs for developing countries: from political "philanthropy" to regulated markets? In: Moatti JP, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.169-211. (Collection Sciences Sociales et SIDA).,1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478 were sensitive to the volume of purchase. As patented medicines were being incorporated into the MoH treatment guidelines, price reductions became smaller. This indicates the purchasing power of the government as the sole buyer of large volumes of ARV is effective on price reductions when there is competition. When a new patented medicine is incorporated in the treatment guidelines, the Government is required by law to ensure universal access to it. The company is in an advantageous position, because the Government will have to buy the medicine, even if prices are high. This indicates inelasticity of demand to price. The existence of information on prices and the availability of generic versions in the national and international market are other elements of a price-reduction strategy.2121. Rêgo ECL. Políticas de regulação do mercado de medicamentos: a experiência internacional. Rev BNDES. 2000;7(14):367-400. The first allows the government to oppose the price offered by the company; the second enables the government to acquire cheaper alternatives by the use of compulsory license, even if no immediate local production capacity exists. Atazanavir prices paid by Brazil are higher than the lowest price offered by BMS (discount price) and the generic version (Figure 1). However, Brazil is excluded from the possibility of acquiring either of these alternatives, which weakens its bargaining power in the negotiation. The exclusion is determined by the fact that Brazil is not among the countries benefitting from the BMS price discrimination policy, and because the companies producing the generic versions are under voluntary license agreements with BMS. These licenses restrict the geographical scope of marketing to African countries and to India.f f Médecins Sans Frontières, Access Campaign. Untangling the web of antiretroviral price reductions. 13.ed. Geneva; 2010 [cited 2013 Apr 25]. Available from: http://d2pd3b5abq75bb.cloudfront.net/2012/07/16/14/39/31/171/UTW_13_ENG_Jul2010.pdf In this scenario, the challenge is to overcome the patent barrier. There are options to overcome the patents on medicinesg g World Health Organization. How to develop and implement a national drug policy: updates and replaces: guidelines for developing national drug policies, 1988. 2.ed. Geneva; 2013 [cited 2014 Jan 15]. Available from: http://apps.who.int/medicinedocs/pdf/s2283e/s2283e.pdf ,h h Joint United Nations Programme on HIV/AIDS. Doha+10 trips flexibilities and access to antiretroviral therapy: lessons from the past, opportunities for the future. Geneva: Unaids; 2011 [cited 2014 Jan 20]. Available from: http://www.unaids.org/en/media/unaids/contentassets/documents/unaidspublication/2011/JC2260_DOHA+10TRIPS_en.pdf ,i i United Nations Conference on Trade and Development (UNCTAD). Using intellectual property rights to stimulate pharmaceutical production in developing countries: a reference guide. Geneva: United Nations; 2011 [cited 2014 Jan 20]. Available from: http://unctad.org/en/Docs/diaepcb2009d19_en.pdf and press for price reductions.55. Gadelha CAG, Maldonado J, Vargas M, Barbosa PR, Costa LS. A dinâmica do sistema produtivo da saúde: inovação e complexo econômico-industrial. Rio de Janeiro: Editora Fiocruz; 2012. One of them is the use of a pre-grant opposition (in Brazil, so-called "support to examination") or a post-grant opposition ("nullity") to the granting of the patent. Another option is the issue of compulsory license that, in Brazil, is generally subject to the availability of a generic version in the international market that can meet the country's need, until local production ensures the supply. This is because the local pharmaceutical industry would need a period to start production. Alternatively, the earlier use of a TRIPS flexibility, known as the Bolar exception,22. Chaves GC, Oliveira MA. A proposal for measuring the degree of public health-sensitivity of patent legislation in the context of the WTO TRIPS Agreement. Bull World Health Organ. 2007;85(1):49-56. DOI:10.1590/S0042-96862007000100012 allows for product development during the patent term, facilitating the issuance of a compulsory license and the negotiation process. It would make it possible to produce the medicine more quickly and locally, in addition to furnishing better estimates of production cost. These options do not seem to have been considered among the strategies to increase the Government's bargaining power for atazanavir price reductions. An alternative used by the Brazilian Government, since 2008, when the "Productive Development Policy" was issued and, later, the "Greater Brazil Plan" in 2011, has been to stimulate local production of priority medicines adopted by SUS55. Gadelha CAG, Maldonado J, Vargas M, Barbosa PR, Costa LS. A dinâmica do sistema produtivo da saúde: inovação e complexo econômico-industrial. Rio de Janeiro: Editora Fiocruz; 2012.,2323. Vargas M, Gadelha CAG, Costa LS, Maldonado J. Inovação na indústria química e biotecnológica em saúde: em busca de uma agenda virtuosa. Rev Saude Publica. 2012;46 Supl 1:37-40. DOI:10.1590/S0034-89102012000700006 through PDP. The adoption of PDP for medicines includes both products with and without a monopoly situation. The transfer of the technology must involve a technology holder, a national private producer for production of the active pharmaceutical ingredient and a public producer for the final product, which, in turn, can market the product exclusively in the public sector. In summary, the Government's purchasing power was used to induce local production for medicines and active pharmaceutical ingredients because it guaranteed a market for the preferred producer, for products defined as priorities adopted by MoH (MoH Ordinances 978/2008, 1,284/2010 and subsequently 3,089/2013). Promoting local production and reducing dependence on the external pharmaceutical industry have been the goals of PDP in Brazil. However, the monopoly created by the market guarantee to a preferred producer might have a negative impact on prices.1111. Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One. 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478,1616. Nunn AS, Fonseca EM, Bastos FI, Gruskin S, Salomon JA. Evolution of antiretroviral drug costs in Brazil in the context of free and universal access to AIDS treatment. PLoS Med. 2007;4(11):e305. DOI:10.1371/journal.pmed.0040305 It creates a monopoly for non-patented products and maintains and strengthens the monopoly for those that are patented. Some PDP have been announced since 2009. However, the specific objectives for their use were only initially defined in 2012 (MoH Ordinance 837/2012). The objectives included: the streamlining of the purchasing power of the Government; greater cooperation on technology development and exchanges of knowledge among private and public producers; local production of strategic medicines, which are also expensive and crucial to ensure availability; and progressive negotiations for significant price reductions. The way in which technology development cooperation and exchange of knowledge would be were not detailed, among the specific objectives. The incorporation of technology in an isolated manner is not enough to increase the government's bargaining power. If there is no forecast of additional investments in technological training and workforce training, the transfer of technology in fact will not occur.88. Klein HE, Hasenclever L, Machado CJS. Regulação e difusão de tecnologias e sua influência na capacitação tecnológica em saúde dos países em desenvolvimento. Rev Bras Cienc Tecnol Soc. 2011;2(2):130-49. Without the guarantee of technological and capacity accumulation, local companies will not be empowered to collaborate in the development of newer and better technologies.15,j j Foray D. Technology transfer in the TRIPS age: the need for new types of partnerships between the least developed and most advanced economies. Geneva: ICTSD; 2009 [cited 2014 Jan 20]. (ICTSD Intellectual Property and Sustainable Development Series; issue paper nº 23). Available from: http://ictsd.org/downloads/2012/02/technology-transfer-in-the-trips-age.pdf In addition, only technological accumulation will help to improve the information asymmetry in technology transfer agreements between technology buyer and seller.j j Foray D. Technology transfer in the TRIPS age: the need for new types of partnerships between the least developed and most advanced economies. Geneva: ICTSD; 2009 [cited 2014 Jan 20]. (ICTSD Intellectual Property and Sustainable Development Series; issue paper nº 23). Available from: http://ictsd.org/downloads/2012/02/technology-transfer-in-the-trips-age.pdf It will also allow the estimate of medicines production costs based on knowledge of companies margins and increase the potential to issue compulsory licenses through local production, if negotiations are not advantageous. The Brazilian Government announced its intention to implement 10 PDP for local production of ARV between 2009 and the end of 2012.k k Ministério da Saúde. Propostas de Projetos de Parcerias para o Desenvolvimento Produtivo (PDP) aprovadas de 2009 a 2014. Brasília (DF); 2015. [cited 2015 Oct 26]. Available from: http://portalsaude.saude.gov.br/images/pdf/2015/outubro/01/Propostas-de-projeto-de-PDP-aprovadas-de-2009-a-2014-01-10-2015.pdf Among these, is the atazanavir PDP, signed in 2011 between BMS and Farmanguinhos – Instituto de Tecnologia em Fármacos of the Fundação Oswaldo Cruz (public manufacturer), for the voluntary license of the existing patent and technology transfer of the active pharmaceutical ingredient and the 200 mg and 300 mg capsule dosage forms.l l Agência Fiocruz de Notícias. Fundação assina acordo para produção do medicamento Atazanavir. Rio de Janeiro (RJ): Fiocruz; 2011 [cited 2013 Mar 26]. Available from: http://www.agencia.fiocruz.br/funda%C3%A7%C3%A3o-assina-acordo-para-produ%C3%A7%C3%A3o-do-medicamento-atazanavir The present study focuses on aspects of that Agreement related to prices and possible strengthening of the underlying monopoly. The Agreement establishes among its results, a 5.0% per year reduction over five years for both dosage forms. Assuming that the Agreement entered into force in January 2012 and that the starting price was the one paid in 2011, registered in SIASG, it was possible to estimate, by the variation in unit prices, a 25.0% reduction until 2016 for the two dosage forms (Figures 2 and 3). Although the rates for 2012 and 2013 indicate a consistency with the estimated reduction when adjusted by the Consumer Price Index, in nominal values, prices are almost constant for the medicines between 2011 and 2013. In practice, the price reduction is more of reflection of the adjustments to the inflation rate. The most significant price reductions were achieved in the period prior to the signing of PDP. The reduction for the 200 mg capsule was 37.6% between 2009 and 2011. For the 300 mg capsule, the reduction was 49.0% for the same period. Previous studies on voluntary licensing of ARVm m Park C, Moon S, Burrone E, Boulet P, Juneja S, ‘t Hoen E et al. Voluntary licensing: an analysis of current practices and key provisions in antiretroviral voluntary licences. Geneva: Medicines Patent Pool; 2012 [cited 2013 Oct 27]. Available from: http://www.medicinespatentpool.org/wp-content/uploads/Current-Practice-and-Key-Provisions-in-ARV-VLs.pdf ,n n Médecins Sans Frontières, Access Campaign. Barriers to accessing generics: the restrictions posed by certain voluntary license agreements. Geneva; 2012 [cited 2015 Oct 26]. Available from: http://www.msfaccess.org/sites/default/files/MSF_assets/HIV_AIDS/Docs/AIDS_report_UTW15_ENG_2012.pdf have highlighted that the technology holder negotiates restrictive clauses, which may limit the possibility of further price reduction. The agreement between Farmanguinhos and BMS explicitly prevents the production of other dosage forms or fixed-dose combinations, than the 200 mg and 300 mg capsules. However, a fixed-dose combination of atazanavir and ritonavir in heat-stable tablets was included in the WHO treatment guidelines of 2013. If this combination becomes the preferred option and is adopted in the MoH guideline, the capsules produced by Farmanguinhos will soon be obsolete. Some terms of the Agreement may limit the possibility of further price reduction. It is mandatory for Farmanguinhos to buy 100% of the MoH demand in the first three years after the marketing approval from BMS. In the fourth and fifth years, BMS will continue to supply 50.0% of the MoH's demand. If there were any delay in the process of technology transfer to Farmanguinhos or in obtaining the marketing approval, BMS would be ensured the market, even after the patent expiration. The patent will expire soon, therefore, the voluntary license represented an opportunity for BMS to exploit the remaining commercial value of the patent. At the end of 2013, the MPP has negotiated a voluntary license for atazanavir with BMS containing less restrictive provisions than those provided for in the Agreement with Farmanguinhos, as it establishes the possibility of the licensee to produce any kind of dosage form and fixed doses combinations.o o Medicines Patent Pool. License and technology transfer agreement. Geneva; 2013 [cited 2014 Jan 10]. Available from: http://www.medicinespatentpool.org/wp-content/uploads/MPP-License-and-technology-transfer-agreement-Signed.pdf Some issues deserve further analysis. One of them is whether a PDP is the most appropriate strategy to overcome the patent barriers and to achieve price reductions. The Government, by being bound to an agreement, gave up the possibility of adopting other antimonopoly strategies, which may be called for if the national and international environment becomes more competitive. The second is the interface between local production and access. A review of the international literaturep p World Health Organization. Local production for access to medical products: developing a framework to improve public health. Geneva; 2011 [cited 2014 Jan 10]. Available from: http://www.who.int/phi/publications/Local_Production_Policy_Framework.pdf explored this relationship and shows that for some cases the benefit of local production in relation to cost savings is doubtful in the short term, providing examples including Brazil. One the one side, it can be argued that local production can ensure availability of the medicine in the national market. In practice, this availability already exists, because atazanavir, as well as other priority products for PDP, is imported and the public market is attractive enough for multinational companies to continue to supply. From another side, local production could improve the bargaining power in the public purchase of medicines under a monopoly situation, in addition to representing a possibility of strategic supply in the presence of importation difficulties. The volume of acquisition and centralized purchases of patented ARV seem to have little or no effect on price reduction. The case study shows the complexity and the difficulties faced by health authorities to reduce the price of priority medicines in a limited-competition environment. A multi-pronged approach is required to achieve price reductions. The use of TRIPS flexibilities to overcome patent barriers, such as patent oppositions, Bolar exception and compulsory licenses, which were not considered in this case, should also be used as instruments for strengthening the MoH bargaining power in price negotiations. The Agreement, which establishes the PDP for atazanavir, raises several questions regarding the use of these partnerships solely to reduce prices and overcome patent barriers. The terms on which Brazil enters into a PDP can inhibit companies from adhering to international voluntary licenses held by MPP. Further research is needed to understand how these clauses were negotiated and which strategies could have been exploited to expand the ability of the Government to obtain more favorable clauses from the technology holder. If the Government pursues the option of strengthening the local production of medicines through the PDP' strategy, it should also consider research and development investments that stimulate technological accumulation. This would strengthen the Government's bargaining power to negotiate medicines prices under a monopoly situation and would help the sustainability of the SUS universal access policy. # REFERENCES • 1 Barroso W. Contribuição ao estudo do subsídio ao exame de pedido de patente no Brasil. In: Corrêa M, Cassier M, organizadores. Aids e saúde pública: contribuições à reflexão sobre uma nova economia política do medicamento no Brasil. Rio de Janeiro: EDUERJ; 2010. p.203-40. • 2 Chaves GC, Oliveira MA. A proposal for measuring the degree of public health-sensitivity of patent legislation in the context of the WTO TRIPS Agreement. Bull World Health Organ 2007;85(1):49-56. DOI:10.1590/S0042-96862007000100012 • 3 D'Almeida C, Hasenclever L, Krikorian G, Sweet C, Coriat B, Orsi F. 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Brazilian policy of universal access to AIDS treatment: sustainability challenges and perspectives. AIDS 2007;21Suppl 4:S37-45. DOI:10.1097/01.aids.0000279705.24428.a3 • 8 Klein HE, Hasenclever L, Machado CJS. Regulação e difusão de tecnologias e sua influência na capacitação tecnológica em saúde dos países em desenvolvimento. Rev Bras Cienc Tecnol Soc 2011;2(2):130-49. • 9 Lucchini S, Cisse B, Duran S, Cenival M, Comiti C, Gaudry M et al. Decrease in prices of antiretroviral drugs for developing countries: from political "philanthropy" to regulated markets? In: Moatti JP, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.169-211. (Collection Sciences Sociales et SIDA). • 10 Luo J, Oliveira MA, Ramos MBC, Maia A, Osorio-de-Castro CGS. Antiretroviral drug expenditure, pricing and judicial demand: an analysis of federal procurement data in Brazil from 2004–2011. BMC Public Health 2014;14:367. DOI:10.1186/1471-2458-14-367 • 11 Meiners C, Sagaon-Teyssier L, Hasenclever L, Moatti JP. Modeling HIV/AIDS drug price determinants in Brazil: is generic competition a myth? PLoS One 2011;6(8):e23478. DOI:10.1371/journal.pone.0023478 • 12 Melo LM. Modelos tradicionais de concorrência. In: Kupfer D, Hasenclever L, organizadores. Economia industrial: fundamentos teóricos e práticas no Brasil. 2.ed rev. ampl. Rio de Janeiro: Elsevier; 2013. Cap.1, p.3-14. • 13 Moon S, Jambert E, Childs M, Schoen-Angerer T. A win-win solution?: a critical analysis of tiered pricing to improve access to medicines in developing countries. Global Health 2011;7:39. DOI:10.1186/1744-8603-7-39 • 14 Morettin PA, Bussab WO. Estatística básica. 8.ed. Rio de Janeiro: Saraiva; 2013. • 15 Noblet J-P, Simon E, Parent R. Absorptive capacity: a proposed operationalization. Knowl Manag Res Pract 2011;9(4):367-77. DOI:10.1057/kmrp.2011.26 • 16 Nunn AS, Fonseca EM, Bastos FI, Gruskin S, Salomon JA. Evolution of antiretroviral drug costs in Brazil in the context of free and universal access to AIDS treatment. PLoS Med 2007;4(11):e305. DOI:10.1371/journal.pmed.0040305 • 17 Oliveira MA, Esher A. Acesso universal ao tratamento para as pessoas vivendo com HIV/Aids no Brasil. In: Bermudez JAZ, Oliveira MA, Esher A, organizadores. Acceso a medicamentos: derecho fundamental, papel del Estado. Rio de Janeiro: Fiocruz/OPAS; 2004. p.233-50. • 18 Orsi F, Hasenclever L, Fialho B, Tigre P, Coriat B. Intellectual property rights, anti-AIDS policy and generic drugs: lessons from the Brazilian Public Health Program. In: Moatti J-P, Coriat B, Souteyrand Y, Barnett T, Dumoulin J, Flori Y-A, editors. Economics of AIDS and access to HIV/AIDS care in developing countries: issues and challenges. Paris: Agence Nationale de Recherche sur le SIDA; 2003. p.109-35. (Collection Sciences Sociales et SIDA). • 19 Pinheiro ES, Vasan A, Kim JY, Lee E, Guimier JM, Perriens J. Examining the production costs of antiretroviral drugs. AIDS 2006;20(13):1745-52. DOI:10.1097/01.aids.0000242821.67001.65 • 20 Possas C, Scapini R, Simão M. Sustentabilidade da política brasileira de acesso universal e gratuito aos medicamentos ARV: conquistas e desafios. In: Possas C, Larouzé B, editores. Propriedade intelectual e políticas públicas para o acesso aos antirretrovirais nos países do Sul. Rio de Janeiro: ANRS/ E-Papers; 2013. p.199-219. • 21 Rêgo ECL. Políticas de regulação do mercado de medicamentos: a experiência internacional. Rev BNDES 2000;7(14):367-400. • 22 Rodrigues WCV, Soler O. Licença compulsória do efavirenz no Brasil em 2007: contextualização. Rev Panam Salud Publica 2009;26(6):553-9. DOI:10.1590/S1020-49892009001200012 • 23 Vargas M, Gadelha CAG, Costa LS, Maldonado J. Inovação na indústria química e biotecnológica em saúde: em busca de uma agenda virtuosa. Rev Saude Publica 2012;46 Supl 1:37-40. DOI:10.1590/S0034-89102012000700006 • 24 Waning B, Kaplan W, King AC, Lawrence DA, Leufkens HG, Fox MP. Global strategies to reduce the price of antiretroviral medicines: evidence from transactional databases. Bull World Health Organ 2009;87(7):520-8. DOI:10.1590/S0042-96862009000700013 • 25 Waning B, Kyle M, Diedrichsen E, Soucy L, Hochstadt J, Barnighausen T et al. Intervening in global markets to improve access to HIV/AIDS treatment: an analisys of international policies and the dynamics of global antiretroviral medicines markets. Global Health 2010;6:9. DOI:10.1186/1744-8603-6-9 # Publication Dates • Publication in this collection 2015	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3044843375682831, "perplexity": 26791.053320249957}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780060803.2/warc/CC-MAIN-20210928122846-20210928152846-00637.warc.gz"}
https://sciencesprings.wordpress.com/2022/09/20/from-alice-at-cernch-alice-pins-down-hypermatter-properties/	## From ALICE at CERN(CH): “ALICE pins down hypermatter properties” 9.20.22 The collaboration’s latest study of a “strange” and unstable nucleus known as the hypertriton offers new insight into the particle interactions that may take place at the hearts of neutron stars. The international ALICE collaboration at the Large Hadron Collider (LHC) has just released the most precise measurements to date of two properties of a hypernucleus that may exist in the cores of neutron stars. Atomic nuclei and their antimatter counterparts, known as antinuclei, are frequently produced at the LHC in high-energy collisions between heavy ions or protons. On a less frequent but still regular basis, unstable nuclei called hypernuclei are also formed. In contrast to normal nuclei, which comprise just protons and neutrons (that is, nucleons), hypernuclei are also made up of hyperons – unstable particles containing quarks of the strange type. Almost 70 years since they were first observed in cosmic rays, hypernuclei continue to fascinate physicists because they are rarely produced in the natural world and, although they are traditionally made and studied in low-energy nuclear-physics experiments, it’s extremely challenging to measure their properties. At the LHC, hypernuclei are created in significant quantities in heavy-ion collisions, but the only hypernucleus observed at the collider so far is the lightest hypernucleus, the hypertriton, which is composed of a proton, a neutron and a Lambda – a hyperon containing one strange quark. In their new study, the ALICE team examined a sample of about one thousand hypertritons produced in lead–lead collisions that occurred in the LHC during its second run. Once formed in these collisions, the hypertritons fly for a few centimetres inside the ALICE experiment before decaying into two particles, a helium-3 nucleus and a charged pion, which the ALICE detectors can catch and identify. The ALICE team investigated these daughter particles and the tracks they leave in the detectors. By analysing this sample of hypertritons, one of the largest available for these “strange” nuclei, the ALICE researchers were able to obtain the most precise measurements yet of two of the hypertriton’s properties: its lifetime (how long it takes to decay) and the energy required to separate its hyperon, the Lambda, from the remaining constituents. These two properties are fundamental to understanding the internal structure of this hypernucleus and, as a consequence, the nature of the strong force that binds nucleons and hyperons together. The study of this force is not only interesting in its own right but can also offer valuable insight into the particle interactions that may take place in the inner cores of neutron stars. These cores, which are very dense, are predicted to favour the creation of hyperons over purely nucleonic matter. Measurements of the hypertriton’s lifetime performed with different techniques over time, including ALICE’s new measurement (red). The horizontal lines and boxes denote the statistical and systematic uncertainties, respectively. The dashed-dotted lines represent different theoretical predictions. (Image: ALICE collaboration) The new ALICE measurements indicate that the interaction between the hypertriton’s hyperon and its two nucleons is extremely weak: the Lambda separation energy is just a few tens of kiloelectronvolts, similar to the energy of X-rays used in medical imaging, and the hypertriton’s lifetime is compatible with that of the free Lambda. In addition, since matter and antimatter are produced in nearly equal amounts at the LHC, the ALICE collaboration was also able to study antihypertritons and determine their lifetime. The team found that, within the experimental uncertainty of the measurements, antihypertriton and hypertriton have the same lifetime. Finding even a slight difference between the two lifetimes could signal the breaking of a fundamental symmetry of nature, CPT symmetry. With data from the third run of the LHC, which started in earnest this July, ALICE will not only further investigate the properties of the hypetriton but will also extend its studies to include heavier hypernuclei.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8473496437072754, "perplexity": 1422.213430193264}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296943750.71/warc/CC-MAIN-20230322051607-20230322081607-00720.warc.gz"}
http://talkstats.com/threads/frejection-region-using-t.2049/	# Frejection region using T? #### sinful ##### New Member not sure I understand this and any help would be great. One-Sample T test for VCR_price Null Hypothesis: MU = 215 Alternative hyp: MU > 215 mean 245.23 STD error 15.620 Mean - HO 30.227 Lo 95% CI - 2.2567 Up 95% CO - 62.711 T 1.94 DF 21 P 0.0333 cases included 22 Missing Cases 0 that is the information given, the question is ::: Find a rejection region appropriate for this test if we are using alpha= 0.05	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8535680770874023, "perplexity": 15515.829407038675}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-39/segments/1568514573832.23/warc/CC-MAIN-20190920050858-20190920072858-00490.warc.gz"}
https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=16305	Bug 16305 - Seeking more consistent package descriptions and citations Seeking more consistent package descriptions and citations Status: NEW None R Unclassified Wishlist (show other bugs) R 3.1.2 x86_64/x64/amd64 (64-bit) Windows 64-bit P5 enhancement R-core Reported: 2015-04-08 20:32 UTC by Philippe Liège 2015-04-09 07:13 UTC (History) 1 user (show) enaux06 Attachments Note You need to log in before you can comment on or make changes to this bug. Philippe Liège 2015-04-08 20:32:52 UTC Hello, The following command provides a convenient way of citing R packages e.g. as footnotes into a LateX document using R and Sweave/knitr. > paste(capture.output(print(citation('xtable'),style='latex')),collapse='') Nicely formatted citations can be obtained using bibtex or biblatex. However, this increases unnecessarily the compiling time when a full bibliography is not needed. The expected results looks like: > paste(capture.output(print(citation('gdata'),style='latex')),collapse="") [1] "Warnes GR, Bolker B, Gorjanc G, Grothendieck G, Korosec A, Lumley T, MacQueen D, Magnusson A, Rogers J and others (2014).\\emph{gdata: Various R programming tools for data manipulation}.R package version 2.13.3, \\url{http://CRAN.R-project.org/package=gdata}." However, some packages cannot be formatted this way: The expected results looks like: > paste(capture.output(print(citation('Hmisc'),style='latex')),collapse="") [1] "Jr FEH, Dupont wcfC and others. m (2015).\\emph{Hmisc: Harrell Miscellaneous}.R package version 3.15-0, \\url{http://CRAN.R-project.org/package=Hmisc}." This occurs when standard text has been added in the "given" or "family" entries. > citation('Hmisc')\$author [1] "Frank E Harrell Jr " "with contributions from Charles Dupont" "many others." Other package are using formatting commands such as \bold or \bsl, etc. that requires loading additional packages (amsmaths, txtcmds, etc.) in the preamble of the LaTex document. Very similar text formatting can be obtained using standard Latex commands. paste(capture.output(print(citation('texreg'),style='latex')),collapse="") [1] "Leifeld P (2013).texreg: Conversion of Statistical Model Output in R to \\bsl{}LaTeX and HTML Tables.''\\emph{Journal of Statistical Software}, \\bold{55}(8), pp. 1--24.\\url{http://www.jstatsoft.org/v55/i08/}." Would it be possible to improve consistency in package descriptions and citations? Regards, Philippe	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.945605456829071, "perplexity": 17688.24789523372}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-09/segments/1487501172017.60/warc/CC-MAIN-20170219104612-00159-ip-10-171-10-108.ec2.internal.warc.gz"}
http://pldml.icm.edu.pl/pldml/element/bwmeta1.element.bwnjournal-article-doi-10_4064-sm195-2-2	PL EN Preferencje Język Widoczny [Schowaj] Abstrakt Liczba wyników Czasopismo ## Studia Mathematica 2009 \| 195 \| 2 \| 113-125 Tytuł artykułu ### Dimensions of non-differentiability points of Cantor functions Autorzy Treść / Zawartość Warianty tytułu Języki publikacji EN Abstrakty EN For a probability vector (p₀,p₁) there exists a corresponding self-similar Borel probability measure μ supported on the Cantor set C (with the strong separation property) in ℝ generated by a contractive similitude $h_{i}(x) = a_{i}x + b_{i}$, i = 0,1. Let S denote the set of points of C at which the probability distribution function F(x) of μ has no derivative, finite or infinite. The Hausdorff and packing dimensions of S have been found by several authors for the case that $p_{i} > a_{i}$, i = 0,1. However, when p₀ < a₀ (or equivalently p₁ < a₁) the structure of S changes significantly and the previous approaches fail to be effective any more. The present paper is devoted to determining the Hausdorff and packing dimensions of S for the case p₀ < a₀. Słowa kluczowe Kategorie tematyczne Czasopismo Rocznik Tom Numer Strony 113-125 Opis fizyczny Daty wydano 2009 Twórcy autor • Department of Mathematics, East China Normal University, Shanghai 200241, P.R. China autor • Department of Mathematics, East China Normal University, Shanghai 200241, P.R. China autor • Department of Mathematics, East China Normal University, Shanghai 200241, P.R. China Bibliografia Typ dokumentu Bibliografia Identyfikatory	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8174346685409546, "perplexity": 874.6764955756105}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623488507640.82/warc/CC-MAIN-20210622033023-20210622063023-00001.warc.gz"}
http://xml.jips-k.org/pub-reader/view?doi=10.3745/JIPS.03.0096	# LBP and DWT Based Fragile Watermarking for Image Authentication Chengyou Wang* , Heng Zhang* and Xiao Zhou* ## Abstract Abstract: The discrete wavelet transform (DWT) has good multi-resolution decomposition characteristic and its low frequency component contains the basic information of an image. Based on this, a fragile watermarking using the local binary pattern (LBP) and DWT is proposed for image authentication. In this method, the LBP pattern of low frequency wavelet coefficients is adopted as a feature watermark, and it is inserted into the least significant bit (LSB) of the maximum pixel value in each block of host image. To guarantee the safety of the proposed algorithm, the logistic map is applied to encrypt the watermark. In addition, the locations of the maximum pixel values are stored in advance, which will be used to extract watermark on the receiving side. Due to the use of DWT, the watermarked image generated by the proposed scheme has high visual quality. Compared with other state-of-the-art watermarking methods, experimental results manifest that the proposed algorithm not only has lower watermark payloads, but also achieves good performance in tamper identification and localization for various attacks. Keywords: Discrete Wavelet Transform (DWT) , Fragile Watermarking , Image Authentication , Local Binary Pattern (LBP) , Semi-blind Detection ## 1. Introduction The development of multimedia and Internet technologies makes it more convenient for us to transmit and store digital images. At the same time, due to the massive emergence of image-editing software, digital images can be easily manipulated according to our own minds. Therefore, the integrity and authenticity of images have been seriously challenged. To solve this problem, a new technology called digital watermarking arises at the historic moment. Its main idea is to insert the secret information associated with host image into the image itself. According to the embedding domain, digital watermarking algorithms can be classified into two categories, namely spatial domain watermarking and frequency domain watermarking [1,2]. In spatial domain, the watermarking message is inserted by modifying pixel values directly. In frequency domain, the transform coefficients are modulated by the watermarking message. Many watermarking algorithms have been presented in the last few years. In terms of different functions, these watermarking algorithms can be further split into robust watermarking algorithm and fragile watermarking algorithm [3,4]. Generally, the robust watermark can resist common attacks, which is usually utilized for copyright authentication. The fragile watermark is sensitive to modifications, and it is usually applied in image content authentication. In this paper, we focus on the fragile watermarking algorithm used for tamper identification and localization. Many researchers have made great efforts in this field. The most typical fragile watermarking method is the watermarking algorithm based on the least significant bit (LSB), which was proposed by Walton [5]. In his method, the check-sum of the seven most significant bits is embedded into the LSB of each pixel. Though it is simple, this scheme is less secure and provides very limited ability in tamper detection. To overcome this defect, a lot of improved methods have been presented. Liu et al. [6] introduced a fragile watermarking algorithm based on chaotic system and pixel-pairs. The watermark is obtained by mapping the difference image between the original image and chaotic image into a binary image. Then the watermark is inserted into the LSBs of original image. Rawat and Raman [7] suggested a chaotic pattern based fragile watermarking method in which a scrambled watermark is generated by applying exclusive-or operation between a binary watermark image and a chaotic image produced by logistic map. These two methods achieve good performance under some common attacks, but they cannot resist the content-only attack. To address this issue, Teng et al. [8] presented an improved fragile watermarking algorithm on the basis of [7]. Compared with the method in [7], the image content is taken into account during the watermark embedding process [8]. Recently, the local binary pattern (LBP) operator was introduced into watermarking field [9,10]. A semi-fragile watermarking based on LBP operators in spatial domain was proposed by Zhang and Shih [9]. A binary watermark is inserted into the host image by adjusting the neighborhood pixel values in each block using its LBP pattern. Experimental results prove that this algorithm is robust against general image processing operations to a certain extent, such as contrast adjustment and JPEG compression. However, the main drawback of these watermarking schemes mentioned above is that they are not blind in tamper detection. The original watermark or image is still needed when the detection process is applied on the receiving side. This is not practicable because the original watermark or image is not always available. So the semi-blind and blind watermarking scheme with high detection accuracy becomes a research focus. Benrhouma et al. [11] suggested a fragile watermarking algorithm for blind tamper detection in which the watermark is constructed by the local pixel contrast between the neighborhood pixel values and average pixel value of each block. However, a false alarm exists in the detection result. Preda [12] proposed a semi-fragile watermarking in wavelet domain. In his method, the wavelet coefficients are firstly permuted by using a secret key, and then they are divided into different groups. A binary random sequence formed by the secret key is adopted as the watermark. By means of quantization, a watermarking bit is inserted into a group of coefficients. This scheme achieves better image quality with low watermark payloads. However, in tamper detection, many noise dots are spread all over the image which reduces the detection precision. To clean the noise dots, the filtering and mathematical morphology operations are adopted in [12]. However, the intensity of post-processing operations should be different for different tampered images, which is hard to achieve. This paper presents a fragile watermarking algorithm based on LBP and discrete wavelet transform (DWT) for image tamper detection. The LBP pattern of low frequency wavelet coefficients is served as authentication watermark and inserted into the LSB of the maximum pixel value in each image block. To ensure the security of the proposed algorithm, the watermark is permuted by a logistic map before it is embedded into the host image. In addition, the embedding positions are stored beforehand and served as a key matrix to extract the watermark in detection process. In other words, the proposed watermarking method is semi-blind. Compared with other fragile watermarking methods, the proposed scheme not only has much lower watermark payloads, but also can detect and locate the tampered regions accurately. The remainder of this paper is organized as follows. Section 2 makes a brief explanation for LBP operator and logistic map. In Section 3, the proposed algorithm is described which includes watermark embedding process and tamper detection process. Experimental results and analysis are illustrated in Section 4. Section 5 concludes the paper. ## 2. LBP Operator and Logistic Map 2.1 LBP Operator The LBP operator was first proposed by Ojala et al. [13] and conventionally used as a kind of texture descriptor. It describes the spatial relationship between a central pixel value and its neighborhood pixel values, and this relationship is represented by a set of binary numbers. In terms of this good property, the LBP operator has been widely applied in texture analysis [14] and face recognition [15]. The LBP operator is defined as a circular symmetric model with radius r, and the total numbers of involved neighborhood pixels are denoted as p. The relation between r and p can be expressed as: ##### (1) [TeX:] $$p = ( 2 r + 1 ) ^ { 2 } - 1.$$ The neighborhood pixels are firstly labeled by the local contrast between the central pixel value and neighborhood pixel values. If the value of neighborhood pixel is larger than that of the pixel in the center, the corresponding position is assigned to 1. Otherwise, it will be assigned to 0. Then we get a binary pattern of the image block. After binary-to-decimal conversion, the LBP value of the central pixel is obtained, which is utilized to reflect the texture information of local region. Considering a circular symmetric neighborhood (p, r), this process can be defined as: ##### (2) [TeX:] $$L B P _ { ( p , r ) } = \sum _ { i = 1 } ^ { i = p } 2 ^ { i } \times S \left( g _ { i } - g _ { c } \right),$$ ##### (3) [TeX:] $$S \left( g _ { i } - g _ { c } \right) = \left\{ \begin{array} { l } { 1 , g _ { i } - g _ { c } \geq 0 } \\ { 0 , \text { otherwise } } \end{array} \right.,$$ where gi (i=1,2,...,p) is the gray value of neighborhood pixel, gc is the gray value of central pixel, and S(.) is a threshold function. The LBP pattern can represent the local texture information of an image effectively. Therefore, it has been widely concerned in digital watermarking for image tamper detection in recent years [9,10]. In this article, we use LBP operator to generate the feature information for image authentication. 2.2 Logistic Map The logistic map is a typical chaotic map which is often utilized in information hiding. The general logistic map can be expressed as: ##### (4) [TeX:] $$x _ { n + 1 } = \mu \left( 1 - x _ { n } \right) x _ { n },$$ where μ is a positive constant called control parameter, and xn+1 is the next state of xn ranging from 0 to 1. Here, n∈N is a nonnegative integer. The logistic map could reach to a chaotic pattern under the condition that 3.5699456 < μ < 4 . Besides, the initial condition plays a significant role in logistic map. For different parameter μ and initial value x0, the logistic map is statistically unrelated. Therefore, the initial condition (μ, x0) is usually adopted as the secret key in watermarking scheme to increase the safety of watermark. ## 3. The Proposed Watermarking Scheme In this section, we describe the proposed watermarking algorithm based on LBP and DWT, which includes two main stages: watermark embedding and tamper detection. The concrete steps are presented as follows. 3.1 Watermark Embedding Fig. 1 illustrates the block diagram of watermark embedding, which includes the following steps: Step 1. Since the authentication information is inserted into the LSBs of original image, the LSBs of host image are firstly set to 0. Step 2. The processed image is then decomposed by Haar wavelet transform and the approximation coefficients LL1 are used to generate the original authentication watermark W0. Step 3. A series of non-overlapping sub-blocks with size of 3×3 are obtained by partitioning the approximation wavelet coefficients. Then the LBP operator is performed on each block to form a binary LBP pattern. Due to the good multi-resolution characteristic of wavelet transform, the LBP pattern of 1 LL can reflect the texture feature of original image effectively with less data volume. Fig. 2 illustrates the process of watermark generation, where gi (i=1,2,...,8) denotes the gray value of neighborhood pixel, gc is the central pixel value, wi (i=1,2,...,8) denotes the binary pattern obtained by LBP operator, and wc is calculated by the exclusive-or operation among wi . After Step 3, the approximation wavelet coefficients are all assigned to 0 or 1, which will be served as the original watermark. Step 4. To encrypt the watermark, a pseudo-random sequence is produced by the logistic map with secret keys μ and x0. Then the values in this sequence are rounded to the nearest integers and reshaped into a chaotic image. By using exclusive-or operation (⊕ in Fig. 1) between the original watermark and chaotic image, an encrypted watermark We is formed, whose size is one-quarter of the original image. Step 5. To select watermark embedding positions, the host image is firstly partitioned into nonoverlapping blocks with size of 2×2. The LSB of the maximum pixel value in each block is selected to insert the watermark. If there is more than one pixel with the maximum value, we choose the first one as the embedding position. In other words, only one bit is embedded in each 2×2 image block. In addition, the coordinates of the maximum value in each block are stored in a key matrix K, which will be utilized to extract the watermark on the receiving side. Step 6. After the image reconstruction, the watermark embedding process is finished and the watermarked image is obtained in the end. Block diagram of watermark embedding. Watermark generation. 3.2 Tamper Detection The tamper detection process involves three main procedures including watermark extraction, watermark reconstruction, and tamper localization. The block diagram of tamper detection is illustrated in Fig. 3. The specific steps are as follows: Step 1. The watermarked image or suspicious image is firstly partitioned into 2×2 non-overlapping sub-blocks. With the help of key matrix K, the location of maximum pixel value in each block is determined and the watermarking bit is extracted from its LSB. Therefore, the watermark extraction process is semi-blind. We get the extracted encrypted watermark W'e, whose size is one-fourth of the image. Step 2. To obtain the original feature watermark W'0, a chaotic image is produced by the logistic map with correct keys. Then the original watermark is recovered by the exclusive-or operation between the extracted encrypted watermark and chaotic image. We denote this process as inverse scrambling. Step 3. By applying the first three steps in watermark embedding process, a new watermark is reconstructed which we denote as W1. As mentioned in Section 2.1, the new generated watermark is closely related to the texture of suspicious image. Step 4. The tampered area S is determined by taking the exclusive-or operation between the extracted decrypted watermark W'0 and reconstructed watermark W1 . This process can be expressed as: ##### (5) [TeX:] $$S = W _ { 0 } ^ { \prime } \oplus W _ { 1 }.$$ Block diagram of tamper detection. ## 4. Experimental Results and Analysis We test the performance of the presented watermarking scheme in terms of watermark invisibility and tamper localization ability for various attacks. In the experiment, the control parameter μ and initial state value x0 for logistic map are set as 3.99 and 0.7654, respectively. 4.1 Watermark Invisibility Watermark invisibility is an important assessment index in watermarking schemes, which is usually measured by the quality of watermarked image. Generally, the better the quality of watermarked image is, the better the watermark invisibility of watermarking scheme will be. Several standard test images with size of 256×256 shown in Fig. 4 are used as host images to investigate the performance of the presented algorithm in image quality. Test images: (a) Lena, (b) Clock, (c) Barbara, (d) Boat, (e) Cameraman, and (f) Airplane. To objectively assess the image quality, the peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) index [16] are adopted in this article. Generally, the larger PSNR value corresponds to the better image quality. The SSIM index is frequently adopted to assess the similarity between two images. The value of SSIM ranges from 0 to 1, where 0 means that there is no connection between two images while 1 indicates that the two images are almost the same. To further evaluate the effect of watermark embedding on image pixels, the percentage of distorted pixels caused by watermark embedding is revealed by a ratio called pixel error rate (PER). Its definition can be expressed as: ##### (6) [TeX:] $$\operatorname { PER } = \frac { N _ { \text { error } } } { N _ { \text { total } } },$$ where Nerror is the number of pixels that are different from original image and Ntotal is the number of total pixels. Fig. 5 shows the watermarked versions of test images in Fig. 4. From Fig. 5, we can see that the watermarked images have almost the same subjective quality as the host images. We cannot tell the difference between the original images and the watermarked images by our naked eyes. Table 1 lists the PSNR, SSIM, and PER values of watermarked images mentioned above. From Table 1, it is observed that the average PSNR and SSIM values of these watermarked images can reach to 57.31 dB and 0.9992, respectively, which indicates that the images after embedding is almost the same as host images. The average value of PER is 0.1207, which further suggests that the watermark makes little effect on host images. These objective evaluations prove that the proposed scheme can preserve good image quality. This good performance is closely related to the watermark embedding rule that only one LSB in each image block might be changed by plus or minus 1. Besides, only the maximum pixel value is selected to embed the watermarking bits. Generally, the image pixel with maximum value in image block represents the texture pixel, and the larger the pixel value is, the smaller the impact of watermark on host image will be. In conclusion, the proposed watermarking scheme achieves good performance in image quality with lower watermark embedding payloads. As we know, DWT has good multi-resolution decomposition characteristic. It is identical to a hierarchical sub-band system that the approximation wavelet coefficients 1 LL can be further decomposed by DWT [17]. Therefore, we can take advantage of this property to generate fewer authentication bits and improve the PSNR of watermarked images further. This is feasible in theory because the low frequency wavelet coefficients of the next layer still contain enough information of the image. It could reconstruct the original image with much fewer amounts of data and its LBP pattern can still reflect image’s texture information effectively. Taking two-level DWT for example, the watermark embedding steps are similar to those in Section 3.1. The host image is first transformed twice by DWT, and we get the second-level approximation coefficients 2 LL whose size is one-sixteenth of the host image. Then a binary authentication watermark with the same size can be obtained using LBP operator. After permutation by logistic map, the encrypted binary watermark is inserted into the LSB of the maximum pixel value in each 4×4 image block. In tamper detection, the tampered region can be determined by Eq. (5). In Table 2, different approximation coefficients obtained from different level wavelet decompositions of image Lena with size of 512×512 are adopted to generate the watermarks. From Table 2, we can see that the higher the level of DWT decomposition is, the larger the PSNR and block size will be. Besides, the PSNR and SSIM values can reach to 69.35 dB and 1, respectively. By multi-level DWT decomposition, the watermark payloads are greatly reduced and the quality of watermarked image is thus improved. Watermarked images: (a) Lena, (b) Clock, (c) Barbara, (d) Boat, (e) Cameraman, and (f) Airplane. PSNR, SSIM, and PER values of watermarked images Quality of watermarked images generated by DWT approximation coefficients at different levels 4.2 Performance under Various Attacks In this subsection, several experiments are performed to test the tamper localization ability of the presented algorithm for various attacks. We select the first-level approximation coefficients LL1 of host image with size of 256×256 to generate the watermark. The attacks used in this paper are all completed by Adobe Photoshop CS3. To diminish the effect of noise, the median filter with window size of 2×2 is performed on detection map. The performance of the presented algorithm against different attacks is as follows. 4.2.1 Performance under copy and paste operation Fig. 6 shows the performance of the proposed algorithm under copy and paste operation. The boat in watermarked image Boat is copied and inserted into the same image, and the forged image is obtained which is shown in Fig. 6(b). Fig. 6(c) shows the tamper detection result. As we can see from Fig. 6(c), the tampered region could be revealed accurately in tamper localization map. Performance under copy and paste operation: (a) watermarked image Boat, (b) tampered image, and (c) tamper localization. 4.2.2 Performance under remove operation In this attack, part of watermarked image is removed from the image which includes two categories given in Figs. 7 and 8, respectively. The first remove operation is shown in Fig. 7(b), in which the logo of airplane is cropped from the image directly. But it might leave some modification traces on the image. The second kind of remove operation is shown in Fig. 8(a). The logo of airplane is erased without leaving any trace. The tamper localization results of these two remove operations are illustrated in Fig. 7(c) and Fig. 8(b), respectively. From the tamper localization maps, we can see that the detection results can identify the tampered areas accurately. Performance under the first remove operation: (a) watermarked image Airplane, (b) tampered image, and (c) tamper localization. Performance under the second remove operation: (a) tampered image and (b) tamper localization. 4.2.3 Performance under content-only attack Fig. 9 shows the content-only attack and the corresponding tamper detection result. In content-only attack, a certain area in watermarked image is manipulated intentionally without affecting the watermarking bits in LSBs. Since the watermark in the proposed scheme is generated by the LBP pattern of 1 LL , it is closely related to the content of host image. Therefore, the presented method can resist the content-only attack effectively, which can be shown in Fig. 9(c). Performance under content-only attack: (a) watermarked image Cameraman, (b) tampered image, and (c) tamper localization. 4.2.4 Performance under collage attack Fig. 10 shows the experimental results for collage attack in which the tampered image is composed by two watermarked images. The sailboat in image Boat is copied and inserted into another watermarked image Clock. Due to the fact that collage attack could lead to sharp edges, the local frequency distribution and LBP pattern of host image will be changed. Therefore, the proposed method has good ability in resisting collage attack, which is shown in Fig. 10(d). From the above experiments, we can get the conclusion that the presented method not only can preserve good image quality, but also can detect and locate the tampered region effectively. Performance under collage attack: (a) watermarked image Clock, (b) watermarked image Boat, (c) tampered image, and (d) tamper localization. 4.3 Performance Comparisons In this subsection, we compare the proposed method with other related watermarking schemes in references [7] and [11]. Table 3 illustrates the comparisons among these three methods, where the values in the first three rows are the average PSNR, SSIM, and PER values of watermarked images in Fig. 5, respectively. By using DWT, the average PSNR value of watermarked images obtained by the proposed method has at least 6 dB improvements in comparison with the other two methods. The average values of SSIM and PER of the presented algorithm are also much better. Compared with the methods introduced by Rawat and Raman [7], only a key matrix K and two secret keys ( μ and x0 ) are needed in tamper detection process of the proposed scheme. In other words, the proposed scheme achieves semi-blind detection. In addition, the proposed algorithm can resist the content-only attack effectively. Comparisons among different watermarking methods for image authentication To further evaluate the tamper detection ability of the presented algorithm, the false positive rate (FPR) and false negative rate (FNR) [18] are applied in this paper. The FPR reflects the ratio of authentic pixels that are determined as tampered pixels improperly, while the FNR denotes the ratio of tampered pixels that are falsely determined as authentic pixels. In general, an image authentication algorithm with lower FPR and FNR values has better tamper detection accuracy. Since the watermarking method in [7] is not blind in tamper detection, the original watermark is needed on the receiving side, which is not practical in some cases. Therefore, we only compare the proposed algorithm with Benrhouma et al.’s method [11] in FPR and FNR. Table 4 lists the FPR and FNR values of the above two methods under different cropping sizes. From Table 4, we can see that the proposed method has lower FPR and FNR values than the method in [11]. In conclusion, compared with other algorithms, the proposed scheme achieves greater success in tamper detection by using much lower watermark payloads. FPR and FNR comparisons under different cropping sizes ## 5. Conclusion A fragile watermarking method based on LBP and DWT is presented in this paper. The binary watermark is obtained by applying LBP operator to the wavelet approximation coefficients. To ensure the security of the proposed algorithm, the logistic map is utilized to encrypt the watermark. Then the encrypted watermark is inserted into the LSB of the maximum pixel value in each image block. In addition, the locations of the maximum pixel values are stored in a key matrix and used to extract watermark on the receiving side. Therefore, the proposed watermarking algorithm achieves semi-blind detection. The tampered region is determined by comparing the extracted watermark with the reconstructed watermark. From experimental results, we can see that the watermarked images obtained by the presented algorithm have higher image quality than other methods. Since the LBP pattern can well represent the local texture information, the proposed method achieves good tamper detection results. It can resist various attacks and locate the tampered regions accurately with lower watermark payloads. We also study the quality of different watermarked images where the watermarks are generated by approximation coefficients at different levels. Due to the limitation of conventional LBP operator, the proposed algorithm cannot detect tampered regions at image edges. In the future work, we will address this problem and further improve the tamper localization ability for small regions. In addition, we will research the watermarking scheme with recovery ability. ## Acknowledgement This work was supported by the National Natural Science Foundation of China (No. 61702303, No. 61201371); the Natural Science Foundation of Shandong Province, China (No. ZR2017MF020, No. ZR2015PF004); and the Research Award Fund for Outstanding Young and Middle-Aged Scientists of Shandong Province, China (No. BS2013DX022). ## Biography ##### Chengyou Wang https://orcid.org/0000-0002-0901-2492 He received his M.E. and Ph.D. degrees in signal and information processing from Tianjin University, China, in 2007 and 2010, respectively. He is currently an associate professor and supervisor of postgraduate students at Shandong University, Weihai, China. His current research interests include image/video coding, digital watermarking, and tamper detection. ## Biography ##### Heng Zhang https://orcid.org/0000-0003-1864-5432 He received his B.E. degree in communication engineering from Shandong University of Technology, China, in 2015. He is currently pursuing his M.E. degree in electronics and communication engineering at Shandong University, China. His current research interests include watermarking-based image authentication and tamper detection, and computer vision. ## Biography ##### Xiao Zhou https://orcid.org/0000-0002-1331-7379 She received her M.E. degree in information and communication engineering from Inha University, Korea, in 2005; and her Ph.D. degree in information and communication engineering from Tsinghua University, China, in 2013. She is currently a lecturer and supervisor of postgraduate students at Shandong University, Weihai, China. Her current research interests include channel estimation, image communication, and image watermarking. ## References • 1 G. C. Langelaar, I. Setyawan, R. L. Lagendijk, "Watermarking digital image and video data: A state-of-the-art overview," IEEE Signal Processing Magazine, 2000, vol. 17, no. 5, pp. 20-46. doi:[[[10.1109/79.879337]]] • 2 H. Nyeem, W . Boles, C. Boyd, "Digital image watermarking: Its formal model, fundamental properties and possible attacks," EURASIP Journal on Advances in Signal Processing, 2014, vol. 2014, no. 1, pp. 1-22. doi:[[[10.1186/1687-6180-2014-135]]] • 3 T . Hai, C. M. Li, J. M. Zain, A. N. Abdalla, "Robust image watermarking theories and techniques: A review," Journal of Applied Research and T echnology, 2014, vol. 12, no. 1, pp. 122-138. doi:[[[10.1016/s1665-6423(14)71612-8]]] • 4 K. Sreenivas, V . K. Prasad, "Fragile watermarking schemes for image authentication: A survey," International Journal of Machine Learning and Cybernetics, 2017. https://doi.org/10.1007/s13042-017-0641-4, pp. 1-26. doi:[[[10.1007/s13042-017-0641-4]]] • 5 S. W alton, "Information authentication for a slippery new age," Dr. Dobb ’ s Journal, 1995, vol. 20, no. 4, pp. 18-26. custom:[[[https://www.researchgate.net/publication/239652446_Image_authentication_for_slippery_new_age]]] • 6 S. H. Liu, H. X, Y ao, W . Gao, Y . L. Liu, "An image fragile watermark scheme based on chaotic image pattern and pixel-pairs," Applied Mathematics and Computation, 2007, vol. 185, no. 2, pp. 869-882. doi:[[[10.1016/j.amc.2006.07.036]]] • 7 S. Rawat, B. Raman, "A chaotic system based fragile watermarking scheme for image tamper detection," AEU - International Journal of Electronics and Communications, 2011, vol. 65, no. 10, pp. 840-847. doi:[[[10.1016/j.aeue.2011.01.016]]] • 8 L. Teng, X. Y. Wang, X. K. Wang, "Cryptanalysis and improvement of a chaotic system based fragile watermarking scheme," AEU - International Journal of Electronics and Communications, 2013, vol. 67, no. 6, pp. 540-547. doi:[[[10.1016/j.aeue.2012.12.001]]] • 9 W . Y . Zhang, F . Y . Shih, "Semi-fragile spatial watermarking based on local binary pattern operators," Optics Communications, 2011, vol. 284, no. 16-17, pp. 3904-3912. doi:[[[10.1016/j.optcom.2011.04.004]]] • 10 J. D. Chang, B. H. Chen, C. S. Tsai, "LBP-based fragile watermarking scheme for image tamper detection and recovery," in Proceedings of the IEEE International Symposium on Next-Generation Electronics, Kaohsiung, T aiwan, 2013;pp. 173-176. doi:[[[10.1109/ISNE.2013.6512330]]] • 11 O. Benrhouma, H. Hermassi, A. A. A. El-Latif, S. Belghith, "Chaotic watermark for blind forgery detection in images," Multimedia T ools and Applications, 2016, vol. 75, no. 14, pp. 8695-8718. doi:[[[10.1007/s11042-015-2786-z]]] • 12 R. O. Preda, "Semi-fragile watermarking for image authentication with sensitive tamper localization in the wavelet domain," Measurement, 2013, vol. 46, no. 1, pp. 367-373. doi:[[[10.1016/j.measurement.2012.07.010]]] • 13 T. Ojala, M. Pietikainen, D. Harwood, "A comparative study of texture measures with classification based on feature distributions," Pattern Recognition, 1996, vol. 29, no. 1, pp. 51-59. doi:[[[10.1016/0031-3203(95)00067-4]]] • 14 Z. P . Dan, Y. F. Chen, Z. Yang, G. Wu, "An improved local binary pattern for texture classification," Optik, 2014, vol. 125, no. 20, pp. 6320-6324. doi:[[[10.1016/j.ijleo.2014.08.003]]] • 15 B. Yang, S. C. Chen, "A comparative study on local binary pattern (LBP) based face recognition: LBP histogram versus LBP image," Neurocomputing, 2013, vol. 120, pp. 365-379. doi:[[[10.1016/j.neucom.2012.10.032]]] • 16 H. Shi, X. H. W ang, M. C. Li, J. Bai, B. Feng, "Secure variable-capacity self-recovery watermarking scheme," Multimedia T ools and Applications, 2017, vol. 76, no. 5, pp. 6941-6972. doi:[[[10.1007/s11042-016-3328-z]]] • 17 G. Bhatnagar, B. Raman, "A new robust reference watermarking scheme based on DWT-SVD," Computer Standards and Interfaces, 2009, vol. 31, no. 5, pp. 1002-1013. doi:[[[10.1016/j.csi.2008.09.031]]] • 18 H. Zhang, C. Y . Wang, X. Zhou, "Fragile watermarking for image authentication using the characteristic of SVD," Algorithmsarticle no. 27, 2017, vol. 10, no. article 27. doi:[[[10.3390/a10010027]]] Table 1. PSNR, SSIM, and PER values of watermarked images Image PSNR (dB) SSIM PER Lena 57.31 0.9993 0.1208 Clock 57.32 0.9988 0.1204 Barbara 57.31 0.9994 0.1209 Boat 57.32 0.9995 0.1205 Cameraman 57.33 0.9990 0.1202 Airplane 57.28 0.9991 0.1216 Average 57.31 0.9992 0.1207 Table 2. Quality of watermarked images generated by DWT approximation coefficients at different levels Level Block Size PSNR (dB) SSIM PER 1 2×2 57.31 0.9998 0.1208 2 4×4 63.24 0.9999 0.0308 3 8×8 69.35 1.0000 0.0076 Table 3. Comparisons among different watermarking methods for image authentication Item Rawat and Raman [7] Benrhouma et al. [11] The Proposed Algorithm PSNR (dB) 51.14 51.16 57.31 SSIM 0.9967 0.9967 0.9992 PER 0.5005 0.4982 0.1207 Content-only attack No Yes Yes Collage attack No Yes Yes Tamper detection Non-blind Blind Semi-blind Table 4. FPR and FNR comparisons under different cropping sizes Algorithm Index 3 2×32 64×64 96×96 128×128 160×160 Benrhouma et al. [11] FPR 0 0.0044 0.0409 0.1015 0.1801 FNR 0.4189 0.3899 0.3943 0.3757 0.3657 The proposed algorithm FPR 0 0 0 0 0.0053 FNR 0.3555 0.3535 0.3568 0.3574 0.3689 Block diagram of watermark embedding. Watermark generation. Block diagram of tamper detection. Test images: (a) Lena, (b) Clock, (c) Barbara, (d) Boat, (e) Cameraman, and (f) Airplane. Watermarked images: (a) Lena, (b) Clock, (c) Barbara, (d) Boat, (e) Cameraman, and (f) Airplane. Performance under copy and paste operation: (a) watermarked image Boat, (b) tampered image, and (c) tamper localization. Performance under the first remove operation: (a) watermarked image Airplane, (b) tampered image, and (c) tamper localization. Performance under the second remove operation: (a) tampered image and (b) tamper localization. Performance under content-only attack: (a) watermarked image Cameraman, (b) tampered image, and (c) tamper localization. Performance under collage attack: (a) watermarked image Clock, (b) watermarked image Boat, (c) tampered image, and (d) tamper localization.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7009558081626892, "perplexity": 1845.0383345894354}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446711396.19/warc/CC-MAIN-20221209112528-20221209142528-00085.warc.gz"}
https://www.arxiv-vanity.com/papers/cond-mat/0111022/	# 25Mg NMR study of the MgB2 superconductor M. Mali J. Roos, A. Shengelaya and H. Keller Physik–Institut, Universität Zürich, CH–8057 Zürich, Switzerland K. Conder Laboratory for Neutron Scattering, ETH Zürich and PSI Villigen, CH–5232 Villigen PSI, Switzerland ###### Abstract NMR spectra and nuclear spin-lattice relaxation time, , have been measured in polycrystalline with a superconducting transition temperature = 39 K in zero magnetic field. From the first order and second order quadrupole perturbed NMR spectrum a quadrupole coupling frequency = 222.0(1.5) kHz is obtained. sK and Knight shift ppm are temperature independent in the normal conducting phase. The Korringa ratio equals to 0.95 which is very close to the ideal value of unity for s-electrons. The comparison of the experimental , , and with the corresponding values obtained by LDA calculations shows an excellent agreement for all three quantities. ###### pacs: The recent discovery of superconductivity in with remarkably high = 39 K Nagamatsu has attracted much attention. In particular the observation of a sizeable boron Budko isotope effect strongly suggests that this simple layered intermetallic compound belongs to the conventional family of phonon mediated BCS superconductors. The relevant electron-phonon coupling constant is proportional to the density of states (DOS) at the Fermi level. So it is important to have experimental data of this quantity in . Nuclear magnetic resonance (NMR) in metals probes the DOS at the Fermi level. The measured quantities, the spin lattice relaxation rate, 1/, and the Knight shift, , are related to the electron spin susceptibility () of electrons close to the Fermi level, specifically , and . In case the atomic site symmetry in the crystal structure is less than cubic and the atom has a nuclear quadrupole moment as it applies for Mg and B in , quadrupolar disturbed NMR delivers in addition valuable information on the electric field gradient (EFG) at the specific nuclear site. Unlike 1/ and the EFG is determined by the distribution of all charges. Up to date only measurements of 1/, , and of the quadrupole coupling to the EFG, expressed by quadrupole coupling frequency , of were performed Kotegawa ; Gerashenko ; Jung ; Tou . While there is reasonable agreement among ’s and relaxation rates, there is a considerable controversy concerning the Knight shifts. While some authors Gerashenko report in the normal conducting state a small temperature independent isotropic shift of 175 ppm, others Jung report a smaller and even temperature dependent shift of approximately 60 ppm, which they attribute to the Fermi-contact interaction. Finally there is also a report Tou of a negative shift of mere 5 ppm attributed to the core polarization. These large discrepancies most likely come from the choice of different materials as references for the Knight shift, as well as from difficulties to measure the small Knight shift of a broad and in addition quadrupolarly shifted central line powder spectrum. As far as we know, there are no experimental data concerning the NMR quantities at the Mg site in , although theoretical predictions based on ab initio local density approximation (LDA) calculations exist for Mg Knight shift, 1/ and EFG Pavarini ; Tsvyashchenko . To some degree the lack of experimental Mg NMR data is understandable considering the fact that the only NMR active isotope has a small magnetic moment and low natural abundance. Consequently the NMR signals are weak even in high magnetic fields. Their detection often demands prohibitively long signal accumulation times. Despite this handicap we were able to measure NMR of the naturally abundant in . Here we report the temperature dependence of Knight shift, spin-lattice relaxation time, and quadrupole coupling frequency of in . We compare the experimental results with the theoretical predictions and we find for all three Mg NMR quantities an excellent agreement. Since all calculations were done by state of the art LDA methods the good agreement between calculated and measured NMR quantities confirms the LDA as a good approximation for . The sample was prepared using stoichiometric amounts of magnesium and boron (99 and 99.99, respectively) in a form of powder. Both components were thoroughly mixed and pressed into pellets. These were placed in a tantalum crucible equipped with a non-vacuum tight cover. The crucible was then sealed under vacuum in a quartz ampoule. The sample was synthesized during heating at 600, 800 and 900 C for one hour at each temperature. X-ray diffraction (XRD) has revealed only small amount of as an impurity phase. DC magnetization measurements (Fig. 1) in a magnetic field of 1 mT (ZFC) yield a transition temperature of 39 K. Before we proceed let us first present a few NMR relevant characteristics of the isotope. The isotope’s natural abundance is 10.0 and its nucleus has spin 5/2, a gyromagnetic ratio , and a quadrupole moment web elements . NMR measurements were performed on a polycrystalline powder sample with a pulsed Fourier-transform spectrometer at an external magnetic field T. Fig. 2 presents the central line powder spectrum gained by Fourier transform of the free induction decay signal induced by a -pulse. The spectrum shows the typical powder pattern of the central transition line of a spin 5/2 system whose levels are disturbed in second order by quadrupole coupling to an axially symmetric EFG. There are two peaks in the spectrum with an indication of a washed out step left and close to the minimum between the peaks. The three features from left to right (see Fig. 2) are the extrema singularities that occur at three powder grain orientations having either , or . Here represents the angle between the largest principal component, , of the EFG tensor and the magnetic field direction. Due to the site symmetry the EFG tensor at Mg and B sites is axially symmetric along the c-axis. Therefore its points into the c-axis direction. From the distance between the two peaks in the spectrum and by help of the second order quadrupole effect expression Abragam Δν=25[I(I+1)−3/4]ν2Q144νL=25ν2Q18νL, we can calculate , defined as νQ≡3eQVzz2I(2I−1)h=3eQVzz20h. Having kHz and Larmor frequency MHz, as determined by NMR from in water solution, one gets kHz. In addition we were able to see the singularities of the first satellites in the satellite powder spectrum presented in the insert of Fig. 2. From the separation of the two first satellite singularities, that are positioned symmetrically with respect to the central line , one gets immediately . For an axially symmetric EFG is simply equal to this separation. The gained kHz agrees very well with the above result. The second result, however, is always more reliable especially in case when the additional Knight shift of the spectrum is anisotropic. Since for there is no quadrupole shift of the central line the step in the spectrum can be used to determine the Knight shift, , of the crystallites whose c-axis is parallel to the magnetic field. From the shift of the step with respect to we get then ppm. Further we noticed that the ratio of the distances of the and singularities with respect to the step is somewhat less than the value 16/9 theoretically expected for an isotropic magnetic shift of the central line powder spectrum. This allows the conclusion that the Knight shift has to be slightly anisotropic. The Knight shift, , for crystallites whose c-axis is perpendicular to must be a bit larger than . We estimate the difference between and to be about +10 ppm. In the normal conducting phase from 294 K down to 19 K we observe that the Knight shift (see Fig. 3) and = 222.0(1.5) kHz remain in error bar limits constant. Such a behavior was also observed for Knight shift Gerashenko and Gerashenko ; Jung . At 19 K the shape of the Mg central line spectrum changes drastically . The peak of the singularity starts to diminish and disappears quickly by cooling below 19 K. In Fig. 4 we exhibit two central line spectra one measured at 6 K and the other one at 294 K that have their intensities scaled to equal height for easier comparison. The peak of the singularity seen in the high temperature spectrum obviously is missing in the 6 K spectrum. We explain this by the appearance of superconductivity in the grains with their c-axis close to the direction perpendicular to the external magnetic field. Nevertheless, a substantial part of the spectrum coming from crystallites with a smaller remains unchanged down to 6 K. This indicates that in a magnetic field of 9 T at 6 K a substantial part of the powder sample still remains normal conducting. In view of the large anisotropy quoted in the literature (2 – 9) LimaPatnaikSimon this comes not as a surprise. However, this has consequences for the determination of NMR quantities and their temperature dependence in the superconducting phase. Necessarily one has to take into account the anisotropy and avoid to average over the NMR signals coming from crystallites with different orientations in the magnetic field. For reliable NMR measurements in the superconducting state large enough single crystals or aligned crystallites of are most desirable. The measurements of the NMR quantity were done by the method of selective inversion of the central line and a subsequent monitoring of the nuclear magnetization recovery at variable delay times t. The relaxation rate defined as , where W represents the spectral density of the fluctuating internal magnetic fields, was extracted by fitting the data to the recovery law M(t)M(∞)=1−Γ[135e−2Wt+845e−12Wt+5063e−30Wt], obtained from the solution of the master equation for a spin 5/2 system in case of magnetic relaxation and selective excitation of the central line AndrewSuter . The constant , also a fit parameter, depends on the inversion ratio of the central line. We measured only in the normal conducting phase at three temperatures 30, 80 and 294 K. The results are presented in Table 1. As expected for a metal the product remains constant. The weighted average of the three values is sK. What is the dominant mechanism of magnetic relaxation and Knight shift of Mg and B in ? In most metals it is the Fermi-contact interaction of the nucleus with the s-electrons at the Fermi level. However, in case of the states near the Fermi level are mainly boron p-electron states with a very small contribution of the s-electrons. Pavarini et al. Pavarini making ab initio LDA calculations of 1/ and at and sites in show that the dominant relaxation mechanism at the nucleus is the interaction with the electronic orbital moment. For the nucleus, however, they predict that the dominant relaxation mechanism is the Fermi-contact interaction, which also dominates the Mg Knight shift. They get for sK, ppm, and ppm which is in excellent agreement with our experimental values sK, ppm, and ppm. Forming the Korringa ratio Carter we get experimentally , where sK for , with and the gyromagnetic ratios for electron and nucleus, respectively. The observed experimental Korringa ratio of 0.95 is very close to the ideal value of unity for s-electrons. This result is another confirmation that the Fermi-contact interaction is indeed the dominant mechanism responsible for relaxation and Knight shift at the Mg site. As next we compare the experimentally determined major principal component, , of the EFG tensor at the Mg site with calculated ab initio within the density functional theory by Tsvyashchenko et al. Tsvyashchenko using the full-potential linearized augmented plane wave method. From the experimentally determined and by use of the quadrupole moment we extract the absolute value V/m . The quadrupole coupling to the EFG and therefore do not depend on the sign of . The gained experimental has then to be compared to the absolute value of the calculated V/m Tsvyashchenko . We note that the agreement of both absolute values is excellent. Tsvashchenko et al. Tsvyashchenko also calculated at the boron site where they get V/m which again is in good agreement with the experimental value V/m Gerashenko ; Jung . The ability to reproduce the experimental NMR quantities at both Mg and B sites by LDA calculations certainly strengthens the confidence into the LDA approach to calculate other material parameters. The authors acknowledge useful discussions with M. Angst. The work was supported in part by the Swiss National Science Foundation.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8724038004875183, "perplexity": 1038.528518159162}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178362899.14/warc/CC-MAIN-20210301182445-20210301212445-00483.warc.gz"}
http://mathhelpforum.com/number-theory/212160-fitting-sine-wave-between-two-lines.html	# Thread: Fitting a sine wave between two lines 1. ## Fitting a sine wave between two lines I have a data set that appears to be made up of two linear regions, separated by what best looks like a sine wave. I know the x and y co-ordinates of the two points at the end of each line segment, x1, x2, y1, y2, and the respective gradient of the lines, m1 and m2. I believe I can parameterise a sine wave of the form "y = Asin(Bx+C)+D" so that it passes through the given points, with the same gradient, but can't work out how to solve for the parameters. Does anybody have any ideas? Thanks! 2. ## Re: Fitting a sine wave between two lines Hi ! The shape of the curve looks like an hyperbola (non orthogonal). I suggest to fit the curve (least squares fitting method, involving 5 parameters) to the general quadratic equation and then, compute the characteristic parameters of the hyperbola. It might be much simpler if you already know the gradient of the asymtotes m1 and m2 . In this case, the equation of the hyperbola is : (y-m1x+C1)(y-m2*x+C2)+C3=0 C1, C2 and C3 can be computed thanks to a linear regression involving 3 parameters (to be defined in relation with C1, C2, C3). 3. ## Re: Fitting a sine wave between two lines Hi, This works, thanks for the reply! If anyone has any ideas, I'd still be interested to know whether it's possible to fit a sine wave under these conditions as a matter of interest. 4. ## Re: Fitting a sine wave between two lines Originally Posted by charlieahill If anyone has any ideas, I'd still be interested to know whether it's possible to fit a sine wave under these conditions as a matter of interest. Fitting a sine function y = Asin(Bx+C)+D to experimental data is a difficult problem. Of course only the points on the area of the sine wave have to be considered and the other points excluded. Since they are 4 parameters A, B, C, D to be optimized, the number of experimental points must be large enough. A method is discribed in the paper "Régressions et équations intégrales" : JJacquelin's Documents \| Scribd (in French. No translation available today) which includes a chapter "Régression sinusoidale" : theory and application pp.21-34 and usable equations pp.35-36	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9314497709274292, "perplexity": 408.67130642927424}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-13/segments/1490218186841.66/warc/CC-MAIN-20170322212946-00049-ip-10-233-31-227.ec2.internal.warc.gz"}
http://www.dlxedu.com/askdetail/3/c883ff0a3a86c076a8a88f75bb98d71c.html	# java path setting on windows 8.1 I am trying to set java path on my windows 8.1, and i installed jdk 8u 64 bit and in environmental variables under system variables there is no PATH found,so i incuded new path variable to set path for jdk and jre ,by copying the bin path of jdk C:\Program Files (x86)\Java\jdk1.8.0_40\bin and i appended jre path C:\Program Files (x86)\Java\jre1.8.0_40,but it doesnt work when i tried in command prompt by typing "java -version" and "javac" it says that java is not a internal or external command. and i had a doubt that to run java through command prompt ,do we need any other installations like turbo c please help me out to set path in my pc,i am a begginer of java thank you javac is not part of jre, but part of jdk. So have `C:\Program Files (x86)\Java\jdk1.8.0_40\bin;C:\Program Files (x86)\Java\jre1.8.0_40\bin` in the path. As Anand noted, the `;` is missing as well. This path is wrong - C:\Program Files (x86)\Java\jdk1.8.0_40C:\Program F iles (x86)\Java\jre1.8.0_40\bin you need a `;` in between the two different paths. C:\Program Files (x86)\Java\jdk1.8.0_40\bin;C:\Program F iles (x86)\Java\jre1.8.0_40\bin If you are trying to add the path in the user variables ``````JAVA_HOME=C:\Program Files\Java\jdk1.8.0_66 `````` in the `JAVA_HOME` don't add any semicolan (`;`) and ``````path=C:\Program Files\Java\jdk1.8.0_66\bin;.; `````` in the path section end of the line add `;.;` to consider all paths and save. Then try to restart system and open the command prompt and try to check 1. `java -version` 2. `javac` JAVA_HOME AND PATH	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9900543689727783, "perplexity": 7086.931671297977}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039741340.11/warc/CC-MAIN-20181113173927-20181113195927-00067.warc.gz"}
https://dsp.stackexchange.com/questions/66173/upsampling-with-time-offsets/66185	# Upsampling with time offsets Suppose I have done 4x oversampling for a continuous time signal, but the successive sampling times have a linearly increasing offset. Specifically, the samples with indices {4k; k=0, 1, 2,...} are correctly sampled at times {4kTs}, but the samples at indices {4k+1; k= 0, 1, 2,..} are sampled at {(4k+1)Ts+e}, the samples at indices {4k+2; k= 0, 1, 2,..} are sampled at {(4k+2)Ts+2e)}, and the samples with indices{4k+3; k= 0, 1, 2,..} are sampled at {(4k+3)Ts+3e)}. How does the spectrum of this oversampled signal look ? • Can you choose one of the answers if satisfactory? Or ask if any clarifications needed. – DSP Rookie Apr 19 at 6:12 • how do I choose ? And what's the relevance of choosing ? – voy82 Apr 20 at 7:57 • You choose by accepting whichever answer satisfied your doubt, by clicking on the tick mark. If none of the answers satisfied your doubt then you comment on the answers what is lacking. – DSP Rookie Apr 20 at 8:12 Answer: You will see residual images of $$X(f)$$ at multiples $$f_s$$, $$2f_s$$ and $$3f_s$$, and distorted image of $$X(f)$$ at non-zero multiples of $$4f_s$$, when sampling in the manner you explained. Depending on value $$e$$, the size of residual will change. I have explained how in detail below. Ideally, sampling at $$4f_s$$ would have completely cancelled those images of $$X(f)$$ at multiples of $$f_s$$, $$2f_s$$ and $$3f_s$$ and you would've seen images of $$X(f)$$ only at multiples of $$4f_s$$ and the magnitude scaled by $$4f_s$$. (Explanation seems long only because I have included lots of pictures to show. Please follow through.) I would like to give you an intuition on how to visualize sampling at any rate $$f_s$$. You probably have a pretty good idea about that. But then I would like to show pictorially what happens when you sample at $$2f_s$$ and then you can extend the idea to $$4f_s$$. 1. Sampling a bandlimited signal $$x(t)$$ at sampling rate $$f_s$$ : When you sample $$x(t)$$ at sampling rate $$f_s$$, you are basically, multiplying $$x(t)$$ with a periodic pulse train with period $$T_s = \frac{1}{f_s}$$ in time domain. Hence, in frequency domain you see a convolution of $$X(f)$$ with Fourier representation of that periodic pulse train. Since the pulse train is periodic, it's Fourier representation will be obtained by computing Fourier Series. The pulse train can be represented by: $$\sum^{\infty}_{k=-\infty} \delta(t - kT_s)$$ and it's Fourier transform as: $$\frac{1}{T_s}\sum^{\infty}_{k=-\infty} \delta(f - kf_s)$$ Notice that the magnitude of Fourier domain representation of the sampling pulse train has scaled up magnitude of $$\frac{1}{T_s} = f_s$$. Assume, frequency representation of $$x(t)$$ as below : Now, as described above, Sampling is nothing but multiplication of $$x(t)$$ with a $$T_s$$ periodic pulse train in time domain and hence a convolution of $$X(f)$$ with Fourier transform of the pulse train in frequency domain. Mathematically, $$x(kT_s) = x(t).\sum^{\infty}_{k=-\infty}\delta(t-kT_s)$$ $$X_{sampled}(f) = X(f) * f_s. \sum^{\infty}_{k=-\infty}\delta(f-kf_s)$$ 1. Now, lets explore what happens when we sample at $$2f_s$$ or when the sampling pulse train becomes $$\frac{T_s}{2}$$ periodic : The sampling pulse train becomes as shown below : The sampling pulse train can be represented by a sum of two $$T_s$$ periodic pulse trains: 1. One pulse train as if $$T_s$$ periodic and centered at 0. 2. Second pulse train as if $$T_s$$ periodic but shifted by $$\frac{Ts}{2}$$. Hence, mathematically it will be as follows: $$\sum^{\infty}_{k=-\infty}\delta(t-k\frac{T_s}{2}) = \sum^{\infty}_{k=-\infty}\delta(t-kT_s) + \sum^{\infty}_{k=-\infty}\delta(t-kT_s - \frac{T_s}{2})$$ Hence, the Fourier Transform of the sampling pulse train will also sum of these 2 trains, as convolution is a linear operation. Also, use the time shift property of Fourier transform to get the result as follows: $$\mathcal F \{ \sum^{\infty}_{k=-\infty}\delta(t-kT_s) + \sum^{\infty}_{k=-\infty}\delta(t-kT_s - \frac{T_s}{2}) \}$$ $$= f_s. \sum^{\infty}_{k=-\infty}\delta(f-kf_s) + f_s.e^{-j\pi \frac{f}{f_s}} \sum^{\infty}_{k=-\infty}\delta(f-kf_s)$$ $$= f_s. \sum^{\infty}_{k=-\infty}\delta(f-kf_s) + f_s.(cos(\pi\frac{f}{f_s})-\mathbb i.sin(\pi \frac{f}{f_s})). \sum^{\infty}_{k=-\infty}\delta(f-kf_s)$$ Notice that the sum is evaluated only at integral multiples of $$f_s$$, because of the $$\delta(f - kf_s)$$. What this means is that $$sin(\pi \frac{f}{f_s})$$ will always be $$0$$, so, no imaginary images of $$X(f)$$ will be seen, and $$cos(\pi \frac{f}{f_s})$$ will be $$1$$ at even multiples of $$f_s$$ and $$-1$$ at odd multiples of $$f_s$$. Pictorially, the fourier transform of pulse train which is used to sample at $$2f_s$$ will look like following : So, the even multiples of $$f_s$$ will be doubled in magnitude to $$2f_s$$ and odd multiples of $$f_s$$ will cancel out each other to cancel the images of $$X(f)$$. This is the reason you see images of $$X(f)$$ only at multiples of $$2f_s$$ when sampling at double the rate, because images of $$X(f)$$ at odd multiples of $$f_s$$ cancel each other out. Now, consider the case which you have explained in your question. When you break your pulse train into 4 pulse trains which are $$T_s$$ periodic individually, but shifted as below: 1. $$\sum^{\infty}_{k=-\infty}\delta(t-kT_s)$$ 2. $$\sum^{\infty}_{k=-\infty}\delta(t-kT_s -\frac{T_s}{4} - e)$$ 3. $$\sum^{\infty}_{k=-\infty}\delta(t-kT_s -\frac{2T_s}{4} - 2e)$$ 4. $$\sum^{\infty}_{k=-\infty}\delta(t-kT_s -\frac{3T_s}{4} - 3e)$$ Conclusion: When you check their Fourier transforms, you will find that images at multiples of $$f_s$$, $$2f_s$$ and $$3f_s$$ will not get cancelled completely because the negative impulses (both real and imaginary) are shifted by $$e$$, $$2e$$ and $$3e$$ respectively. And, image at multiples of $$4f_s$$ will also not be aligned exactly to give a scaling of $$4f_s$$ but they will be fudged around to give a distorted image of $$X(f)$$ except at $$k=0$$, that is the original image of $$X(f)$$ centered around DC. Depending upon the value of e, the real and imaginary images of $$X(f)$$ will have residuals at $$f_s$$, $$2f_s$$ and $$3f_s$$, and images at non-zero multiples of $$4f_s$$ will be fudged around. • Fun-fact: you can still reconstruct the original x(t), because X(f) at DC is still untouched. Meaning, you can still throw 3 in 4 samples and interpolate to get x(t) back. – DSP Rookie Apr 7 at 13:40 The spectrum of the oversampled signal as you describe it would look very odd and is likely not what you are intending to do. Let me explain: First consider each group separately, instead representing what would be the decimated signal if you were sampling at the higher 4x rate as $$f_s$$: Each of the four spectrums would span from frequency = $$0$$ to $$f_s/4$$ and contain all energy within that frequency range as well as all the aliasing from $$f_s/4$$ to $$f_s$$. Each would be translated by a different phase slope in frequency consistent with the time delay each shift represents. First consider the unit delays only and assume the additional time offset $$e = 0$$ to best understand the effect of the unit delays, then we can add in the effect of non-zero $$e$$. Each delay of one sample would add a linear phase in frequency extending negatively from $$0$$ to $$2\pi$$ as the the normalized radian frequency goes from $$0$$ to $$2\pi$$ (Meaning as the frequency goes from $$0$$ to $$f_s$$). Consider the z-transform of an m sample delay: $$\sum_{n=0}^{N-1}x[n-m]z^{-n} = X(z)z^{-m}$$ And the DFT is simply the z transform with z limited to the unit circle; $$z=e^{j2\pi k/N}$$ as k = $$0$$ to $$N-1$$ So here we see that for each delay m, the DFT would be $$X(k)e^{-mj2\pi k/N}$$, with the phase negatively increasing to $$2\pi$$ for m =1, to $$4\pi$$ for m=2, etc. Thus the higher frequencies that are above $$f_s/4$$ are aliased into the $$0$$ to $$f_s/4$$ spectrum with a different phase slope for each of the four groups. As far as the additional time offsets, which may be fractional samples, consider the Fourier Transform of a time delay given as $$\mathscr{F}\{x(t-\tau)\} = e^{-\tau}$$ And we see that the time offsets just add an additional slope to the phase slopes given by the unit delays. The time offset as a fraction of a sample given as $$d$$ would introduce a phase slope according to $$z^{-d}$$ using the method above with limiting z to the unit circle. Importantly, you cannot recreate the interpolated spectrum simply by cascading the samples in frequency as you are describing. As I explained above above you would only be showing the decimated and folded spectrum extending from $$0$$ to $$f_s/4$$, just with four phases of the same bin next to each other. Combining the interpolated spectrum is more complicated as it involves summing all four spectrums with the appropriate phase slope to compensate for the phase introduced as described above. If your signal is bandlimited to $$[-f_0/2,+f_0/2]$$, the digitized signal sampled at $$f_s$$ can be considered as a summation of 4 different sampled signals with offset of $$0$$, $$e$$, $$2e$$, $$3e$$. Assuming $$3e \le 1/f_s$$. First imagine $$e=0$$. This means, you have perfectly oversampled 4x. That is $$f_s = 4 \times f_0$$. It is like you have sampled the signal 4 times with sample rate of $$f_0$$, each of them with offset of $$k/(4f_0)$$, where $$k \in \{0,1,2,3\}$$, interleaved them with 3 zeros and added them. Assume $$T_s = 1/f_s = (1/(4f_0))$$. This is equivalent to $$x_1 = x(0), 0 ,0 ,0, x(4T_s), 0, 0, 0..\\ x_2 = 0 ,x(T_s),0,0,0, x(5T_s),0,0,0.. \\ x_3 = 0 ,0,x(2T_s),0,0,0, x(6T_s),0,0,0.. \\ x_4 = 0 ,0,0,x(3T_s),0,0,0, x(7T_s),0,0,0.. \\ x = x_1 +x_2+x_3+x_4$$ Equivalently in fourier domain $$X(e^{j\omega}) = X_1(e^{j4\omega})+X_2(e^{j4\omega})e^{-j\omega}+X_3(e^{j4\omega})e^{-j2\omega}+X_4(e^{j4\omega})e^{-3\omega}$$ which is same as if you had sampled original signal at $$f_s$$.(This is proved later using MATLAB example for 2x oversampled case). If there were offsets of $$e,2e,3e$$ as you mentioned in each of those copies, $$x_1 = x(0), 0 ,0 ,0, x(4T_s), 0, 0, 0..\\ x_2 = 0 ,x(T_s+e),0,0,0, x(5T_s+e),0,0,0.. \\ x_3 = 0 ,0,x(2T_s+2e),0,0,0, x(6T_s+2e),0,0,0.. \\ x_4 = 0 ,0,0,x(3T_s+3e),0,0,0, x(7T_s+3e),0,0,0.. \\ \hat{x} = x_1 +x_2+x_3+x_4$$ Equivalently in fourier domain $$\hat{X(e^{j\omega})} = X_1(e^{j4\omega})+X_2(e^{j4\omega})e^{-j\omega(1+e)}+X_2(e^{j4\omega})e^{-j2\omega(1+e)}+X_4(e^{j4\omega})e^{-3\omega(1+e)}$$ APPENDIX: To show that if $$x[n]$$ is an $$N$$ sample signal sampled at rate $$f_s$$, it can be shown that it is sum of 2 signals sampled at rate $$f_s/2$$ but with offset of $$1$$ sample and interleaved with zeros and added. That is $$X(e^{j\omega}) = X_1(e^{j2\omega})+X_2(e^{j2\omega})e^{-j\omega}$$. That is $$e=0$$ in the below code, the spectrum of $$x$$ and $$X_1(e^{j2\omega})+X_2(e^{j2\omega})e^{-j\omega}$$ would be same. If $$e=0.25$$, spectrum of $$x$$ would not be same as $$X_1(e^{j2\omega})+X_2(e^{j2\omega})e^{-j\omega(1+e)}$$. clc clear all close all x=randn(1,16)+1irandn(1,16); xph1 = x(1:2:end); xph2 = x(2:2:end); xph1ups=upsample(xph1,2); xph2ups=upsample(xph2,2); e=0.25; F1= fft(xph1ups); F2= fft(xph2ups); F=F1+exp(-1i2pi/16(0+e:1:15+e)).*F2; plot(1:16,abs(fft(x)),'b',1:16,abs(F),'r') • @voy82 They are not the same. You cannot take out the exponentials as common factor. You can check that with the MATLAB script I uploaded. It is not same as $X_1(e^{j2\omega})(1+e^{-j\omega})$ – jithin Apr 7 at 5:40 • thanks ! I was also thinking along same lines. Since X1, X2, X3, X4 in my question represent the spectrums of Nyquist sampled x(t), are they not the same ? So, we should be able to take them out, so as to get X(e^(j4ω)) x (1+exp^(-jw(1+e)) + exp^(-j2w(1+e))+exp^(-j3w(1+e))) – voy82 Apr 7 at 5:40 • hmm.. i think, using your notations above, we should get : X(ej4ω)+X(ej4ω) e−j4ω/(1+e) + X(ej4ω) e−j8ω/(1+e) + X(ej4ω) e−j12ω/(1+e); where X(ejω) is the spectrum of the Nyquist sampled original continuous signal x(t). Would you agree ? I am thinking if for e=0, this gives X(ej4ω). – voy82 Apr 7 at 6:00 • sorry I did not mean to have the "/" there in the "e−j4ω/(1+e)" like terms. I was basically repeating my first comment but with the 4ω, 8ω, 12ω instead of ω, 2ω, 3ω. But you clearly do not seem to agree with it (that we can take the X(ej4ω) out) ! Looking at your matlab code now. thanks ! – voy82 Apr 7 at 6:13 • Repeating my comment because of formatting issue earlier : @voy82 No the (1+e) terms are not in denominator. Sorry if my MATLAB code appears like that. The (1+e) terms are all in numerator. Also for the term $X_1(e^{j4\omega)}$ , the $4\omega$ cannot be taken outside. So you would not get 4$\omega$,8$\omega$,12$\omega$ – jithin Apr 7 at 6:14	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 143, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8819078803062439, "perplexity": 529.9673197465489}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141486017.50/warc/CC-MAIN-20201130192020-20201130222020-00493.warc.gz"}
http://ferrier.org.uk/?cat=87	This I Know I Think Life on the verge of understanding ## Another beautiful equation October 16, 2018 Categories: maths. Tags: maths. Here’s another example of a mathematical identity that is almost magical: $$\frac {\pi} {4} = 1 – \frac{1}{3} + \frac{1}{5} – \frac{1}{7} +…$$ The beauty lies in the apparent simplicity of this, along with the fundamental question of why the interminable expression on the right results in increasingly better approximations to $\pi$. ## More mathematical beauty August 15, 2018 Categories: maths. YouTube now routinely recommends videos to watch based, it says, on my browsing history. I’m not convinced that the algorithm is all that accurate, although so far, at least, I haven’t been offered anything that is completely unconnected with what I might be interested in. Yesterday I was pushed towards a video discussing Euler’s equation. […]	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.632701575756073, "perplexity": 1503.0186642736267}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-04/segments/1547584332824.92/warc/CC-MAIN-20190123130602-20190123152602-00638.warc.gz"}
https://answers.ros.org/question/191154/yaml-vs-xacro/	# yaml vs xacro edit I would like to have a configuration file that I can set some properties like in box use-case here. I have 3 questions regarding this: 1. Which one better suits this purpose, using yaml or xacro? 2. Let say I want to have one property (boxOK, only to illustrate as below) or some of them to be parsed with a delay (I mean it fires after some time, say 20ms after loading the launch file), how do I achieve this? <id="width" value="1"/> <id="length" value="3"/> <id="height" value="3"/> <id="boxOK" value="true"/> <id="width2" value="3"/> <id="length2" value="3"/> <id="height2" value="4"/> <id="width3" value="2"/> <id="length3" value="3"/> <id="height3" value="3"/> 3. In any case, if I would set in either yaml or xacro, where in launch file normally I use something like below: <param name="boxes_num" value="4" /> then, in the node I could invoke and assign like: ros::param::get("boxes_num", boxes_num_); My question is how would I do this using yaml or xacro.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3005566895008087, "perplexity": 4329.574305160847}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320305317.17/warc/CC-MAIN-20220127223432-20220128013432-00109.warc.gz"}
https://www.albert.io/ie/differential-equations/finding-general-solution-to-nonhomogeneous-system-5-and-2	Free Version Difficult # Finding General Solution to Nonhomogeneous System, -5 and 2 DIFFEQ-VEXP18 Which is a general solution to the system of nonhomogeneous differential equations: $$X'=\left(\begin{array}{cc}0 & -1 \\\ 1 & 0 \end{array}\right)X+\left(\begin{array}{c}-5 \\\ 2 \end{array}\right)$$ A $X=c_{1}\left(\begin{array}{c}\cos t \\\ \sin t \end{array}\right)+c_{2}\left(\begin{array}{c}\sin t \\\ -\cos t \end{array}\right)+\left(\begin{array}{c} -2 \\\ -5 \end{array}\right)$ B $X=c_{1}\left(\begin{array}{c}\cos t \\\ \sin t \end{array}\right)+c_{2}\left(\begin{array}{c}\sin t \\\ -\cos t \end{array}\right)+\left(\begin{array}{c} 2 \\\ 5 \end{array}\right)$ C $X=c_{1}\left(\begin{array}{c}\cos t \\\ -\sin t \end{array}\right)+c_{2}\left(\begin{array}{c}\sin t \\\ \cos t \end{array}\right)+\left(\begin{array}{c} -2 \\\ -5 \end{array}\right)$ D $X=c_{1}\left(\begin{array}{c}0 \\\ -1 \end{array}\right) \cos t+c_{2}\left(\begin{array}{c} 1 \\\ 0 \end{array}\right)+\left(\begin{array}{c} -5 \\\ 2 \end{array}\right)$ E None of the above	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6467242240905762, "perplexity": 1187.8284504773585}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-09/segments/1487501171629.92/warc/CC-MAIN-20170219104611-00089-ip-10-171-10-108.ec2.internal.warc.gz"}
https://mathinsight.org/prototypes_more_serious_questions_taylor_polynomials_refresher	# Math Insight ### Prototypes: More serious questions about Taylor polynomials Beyond just writing out Taylor expansions, we could actually use them to approximate things in a more serious way. There are roughly three different sorts of serious questions that one can ask in this context. They all use similar words, so a careful reading of such questions is necessary to be sure of answering the question asked. (The word ‘tolerance’ is a synonym for ‘error estimate’, meaning that we know that the error is no worse than such-and-such) • Given a Taylor polynomial approximation to a function, expanded at some given point, and given a required tolerance, on how large an interval around the given point does the Taylor polynomial achieve that tolerance? • Given a Taylor polynomial approximation to a function, expanded at some given point, and given an interval around that given point, within what tolerance does the Taylor polynomial approximate the function on that interval? • Given a function, given a fixed point, given an interval around that fixed point, and given a required tolerance, find how many terms must be used in the Taylor expansion to approximate the function to within the required tolerance on the given interval. As a special case of the last question, we can consider the question of approximating $f(x)$ to within a given tolerance/error in terms of $f(x_o), f'(x_o), f''(x_o)$ and higher derivatives of $f$ evaluated at a given point $x_o$. In ‘real life’ this last question is not really so important as the third of the questions listed above, since evaluation at just one point can often be achieved more simply by some other means. Having a polynomial approximation that works all along an interval is a much more substantive thing than evaluation at a single point. It must be noted that there are also other ways to approach the issue of best approximation by a polynomial on an interval. And beyond worry over approximating the values of the function, we might also want the values of one or more of the derivatives to be close, as well. The theory of splines is one approach to approximation which is very important in practical applications.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.922443687915802, "perplexity": 277.48325954836196}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500356.92/warc/CC-MAIN-20230206145603-20230206175603-00558.warc.gz"}
http://www.talkstats.com/threads/hierarchical-multiple-regression-total-variance.76076/	# Hierarchical multiple regression - total variance #### TruBluStu ##### New Member What is the total variance accounted for in a Hierarchical model? Is the total variance accounted for the maxium F Change result? EG: In total, x1 and x2 accounted for 38.1% of the variance in y. R2 =0.38, F(2,997) =.323.39, p<.001 or is the total variance treated like a normal multiple regression? EG: In total, x1 and x2 accounted for 38% of the variance in y. R2 =0.38, F(2,997) =.308.34, p<.001 Last edited:	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9562000036239624, "perplexity": 6980.471414097799}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964362930.53/warc/CC-MAIN-20211204033320-20211204063320-00247.warc.gz"}
https://www.physicsforums.com/threads/inverse-square-law-help-please.790996/	Tags: 1. Jan 7, 2015 RichardGib 1. The problem statement, all variables and given/known data If I measure a sound intensity of 1.0 at distance R from its source, what intensity would I measure at distance 3R in a free, unbounded space? What is the difference in decibels? & If I measure a sound pressure of 1.0 at distance R from its source, what pressure would I measure at distance 2R in a free, unbounded space? What is the difference in decibels? 2. Relevant equations N/A 3. The attempt at a solution I am stuck on this. i thought the answer to the first question could be a difference of -18db? Really stuck here... Thankyou! Last edited: Jan 7, 2015 2. Jan 7, 2015 Fightfish The inverse square law simply means that the value of the physical observable involved is inversely proportional to the square of the distance from the source. That is to say, for instance if the distance is doubled, then the value falls to a quarter (half squared). 3. Jan 7, 2015 BvU Hello Richard, welcome to PF :) Please check the PF guidelines (especially #4); the way you post now actually prevents us from helping you further. And you can read up on the subject a little here 4. Jan 7, 2015 RichardGib Thankyou :) Draft saved Draft deleted Similar Discussions: Inverse Square Law HELP PLEASE	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8845289945602417, "perplexity": 874.1562313255728}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886105187.53/warc/CC-MAIN-20170818213959-20170818233959-00161.warc.gz"}
https://googology.fandom.com/wiki/Graatagolenna	11,351 pages The graatagolenna is equal to E100##100##100##100##100##100##100##100##100#100 using Extended Hyper-E notation.[1] The term was coined by Sbiis Saibian. ## Etymology The name of this number is based on the numbers "graatagold" and "gugolenna". ## Approximations in other notations Notation Approximation Chained arrow notation $$100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 100 \rightarrow 101 \rightarrow 2$$ BEAF $$\{100,101,1,9\}$$ Fast-growing hierarchy $$f_{\omega 8+1}(100)$$ Hardy hierarchy $$H_{\omega^{\omega 8+1}}(100)$$ Slow-growing hierarchy (using this system of fundamental sequences) $$g_{\varphi(8,0,0)}(100)$$	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9980292320251465, "perplexity": 18021.01265148058}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320302355.97/warc/CC-MAIN-20220120160411-20220120190411-00060.warc.gz"}
https://docs.galpy.org/en/v1.6.0/reference/potentialrtide.html	# galpy.potential.Potential.rtide¶ Potential.rtide(R, z, phi=0.0, t=0.0, M=None)[source] NAME: rtide PURPOSE: Calculate the tidal radius for object of mass M assuming a circular orbit as $r_t^3 = \frac{GM_s}{\Omega^2-\mathrm{d}^2\Phi/\mathrm{d}r^2}$ where $$M_s$$ is the cluster mass, $$\Omega$$ is the circular frequency, and $$\Phi$$ is the gravitational potential. For non-spherical potentials, we evaluate $$\Omega^2 = (1/r)(\mathrm{d}\Phi/\mathrm{d}r)$$ and evaluate the derivatives at the given position of the cluster. INPUT: R - Galactocentric radius (can be Quantity) z - height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) M - (default = None) Mass of object (can be Quantity) OUTPUT:	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8987058997154236, "perplexity": 2606.8140315193837}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655899209.48/warc/CC-MAIN-20200709065456-20200709095456-00566.warc.gz"}
http://electronics.stackexchange.com/questions/19102/if-the-energy-meter-sees-a-reactive-load-will-it-register-a-lower-reading	# If the energy meter sees a reactive load, will it register a lower reading? At an exhibition on home appliances, I saw this guy hawking his 'energy saver device'. The guy claimed that merely plugging his instrument into the supply would reduce the consumption reported in an energy usage meter by a fourth. He mentioned something about the load seen by the meter being non-resistive ... Not sure if this is the right forum to post the question (feel free to vote for the question to be closed)... Anyhow I find myself wondering - Is this just a sales-pitch (no warranty/guarantee on the device) or is there some fire to the smoke? - SCAM WARNING. These "energy saver" devices usually are simply capacitors, and they don't save you any money. Typical KWH meters are not affected by adding a capacitor. The scam works like so: 1. Many loads in your home are inductors (fridge motor, furnace fan) 2. If you install a capacitor which has just the right value, the current in the power grid leading to your home is reduced. 3. Con artists correctly claim that some energy somewhere is being saved. 4. Con artists correctly claim that industry uses these capacitors to save money 5. Con artist sneakily insinuates that this somehow saves YOU money 6. As evidence, con artist supplies testimonials rather than basic lab test results. So why doesn't this save you money? It's because, while motors do draw extra unnecessary current, the KWH meter on the side of your home is designed to ignore that extra current! Adding a capacitor doesn't change your electric bill. So energy is really being saved, right? Yes: it's energy which otherwise would heat all the power lines between the company generators and your home. The extra capacitor doesn't cause your motors to use less energy. Instead it relieves some load-current on the power grid. The electric company benefits from this ...but the homeowner doesn't! Why then do factories use these Power-Factor Correction capacitors? Ah, for most huge industrial customers, electric utility companies install a different type of KWH meter: one with two dials. One dial is used to bill the customer for real KWH consumed, while the other is used to bill wasted or 'reactive' KWH. These industrial meters do detect the excess current drawn by induction motors. The industrial customers are charged for the unnecessary heating of the power grid. If they install just the right value of capacitor, they can reduce their electric bills. And this brings up one last bit of info. To reduce the excess current in the power grid, the capacitor has to be just the right value! If you have no induction motors in your home, then a PFC capacitor is less than worthless. Adding a PFC capacitor will INCREASE the wasted reactive current, not reduce it. So basically that's part of the dishonesty: selling capacitors of an unknown value in order to cancel out the effects of an unknown number of induction motors ...which aren't being billed by the electric company in the first place. Finally, what about #6 above? The testimonials? I suspect that these are genuine. If you were to install a very expensive PFC capacitor in your home, you'd be bringing in the "stone soup effect." You'd become very aware of any wasted energy. You'd start "helping" the device: turning off lights, turning down the furnace and the air conditioning, perhaps buying better windows and installing improved insulation. The expensive and worthless "stone" has turned into "soup." But you'd save lots more money if you skipped the PFC capacitor scam and just started turning down the hot water heater in the first place. - As an addendum to this, power factor correction is done for household consumers... by legislating active PFC requirements for devices, as done in the EU: electronics.stackexchange.com/questions/47026/… – Fizz Oct 20 '15 at 20:22 " the KWH meter on the side of your home is designed to ignore that extra current"... can you cite your source? – jpcgt Jan 21 at 20:12 The kWh meter (not KWH which means kelvin-watt-henries) meter is as the title suggests a kWh meter. It does not measure reactive power which is measured in kVArh. Look up how power meters work. – transistor Jan 21 at 20:45 @jpcgt my source: the meter itself, taken apart. The mechanical meter multiplies together the instantaneous voltage and current by using coils to produce a 2-phase rotating magnetic field, using this to rotate an aluminum disk against drag from a permanent magnet. If the V and I waveforms are at 90deg (lead or lag,) then the two b-fields will be at zero phase, and the torque upon the aluminum disk is pure AC with zero average, as it would be for ideal capacitive or inductive loads. The disk just vibrates without turning, and the "imaginary" current is ignored. – wbeaty Jan 22 at 6:37 I think this is a perfectly legitimate question. Energy meters like on the side of your house or on the utility pole already measure real energy delivered. If you were to have a purely reactive load, like a capacitor for example, then the energy meter would not increase but you also wouldn't be getting any energy. The capacitor won't get warm. But if you put a current meter in series with the capacitor, you'd see real current. How can this be? No laws of physics have been violated because the voltage and the current are 90 degrees out of phase, something you can't tell just be looking at either in isolation. The utility's electric meter measures the integral of the voltage times the current, so measures only real energy delivered. The utility doesn't like highly reactive loads because it causes currents in the transmission system, which waste power by I*2 R losses which they can't bill for. This is why large electric customers get charged in part by the power factor. This is basically a measure of how far off you'd be assuming the product of independently measured voltage and current gave you real delivered power. For a purely resistive load, the voltage and current are in phase and the power factor is 1. That's what the utilities like. The worst case are purely capacitive or purely inductive loads. The voltage and current are 90 degrees out of phase, so no real power is delivered, and the power factor is 0. In general, the power grid looks somewhat inductive. Utilities combat this various ways. These include banks of capacitors, nagging legistlators to force appliances to have better power factors, and running their generators a little out of phase. The utility term for the latter is "reactive power". In most cases you're actually doing the utility a favor by plugging a little capacitance into your outlet. Unfortunately there are lots of snake oil salesman ready to exploit the fact that most people don't understand that independently measured voltage times current doesn't give you delivered power. There may be some slight saving to you in presenting a better power factor, but 25% "less electricity used" sounds like pure BS, and your electric meter already measures real delivered power anyway. - It depends on the meter. If the meter reads only active power (P), then plugging in a non-resistive load wouldn't show up on the meter. If however the meter reads the total power (S which is $\sqrt{P^2+Q^2}$, where Q is the reactive power), then if your house consumes a lot "inductive" power, plugging in something with "capacitive" power would indeed lower the total reactive power ("inductive" power cancels with "capacitive" power). If in the equation above you minimize Q, you would minimize S, which would minimize your bill. I don't know how they bill electricity over in the US, but if the meter reads active power only, then this device would be a sham. If it reads S, which I highly doubt, you MAY experience a minor bill. - Cool. Thank you. For the record (+: I'm in India – Everyone Sep 5 '11 at 19:29 @Everyone If you really want the answer to the question, you'd need to check this with someone who is familiar with the internal operation of the meter or to check the energy bill. In addition to meters which read only active power or only apparent power, there are meter types which read both active and reactive energy and which display the values. If that's your case, then it would be easy to see how much the device will help. – AndrejaKo Sep 5 '11 at 20:00 Also do note that the reactive power may be more or less expensive than active power and that there might be incentives in place to minimize it. For example I get considerable increase in reactive power cost if it's over 5% of total consumed power. If you have a power meter that measures only the apparent power, then you'd have to determine how much power is active and how much is reactive and there's no simple and easy way to do that for the whole household. If you have a meter that only measures the active power, then the device won't ever pay for itself. – AndrejaKo Sep 5 '11 at 20:05 One point i want to add is that , if you somehow calculate the right amount of capacitor bank to be used to cancel out the excess reactive power in domestic grid, then you can save some money in using thin wiring than the thick wiring that you would have used when you install some large appliance in your home. the reactive current may not register itself in the domestic meters but it will flow in the household wiring. - Any device installed after the utilities meter can't and never can reduce energy consumption! Simple as that! - A switch can. Turn off the switch, and energy consumption goes to zero. I could come up with lots of other examples, but if they are useful is debatable. "Never" makes for such a blanket statement. – user3624 Sep 2 '13 at 14:34	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.585218608379364, "perplexity": 1411.5546765425013}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-22/segments/1464049274756.45/warc/CC-MAIN-20160524002114-00117-ip-10-185-217-139.ec2.internal.warc.gz"}
https://reference.globalspec.com/standard/3842897/astm-e918-83-1999	# ASTM International - ASTM E918-83(1999) ## Standard Practice for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure historical Organization: ASTM International Publication Date: 10 April 1999 Status: historical Page Count: 5 ICS Code (Ignitability and burning behaviour of materials and products): 13.220.40 ICS Code (Products of the chemical industry in general): 71.100.01 ##### scope: 1.1 This practice covers the determination of the lower and upper concentration limits of flammability of combustible vapor-oxidant mixtures at temperatures up to 200°C and initial pressures up to as much as 1.38 MPa (200 psia). This practice is limited to mixtures which would have explosion pressures less than 13.79 MPa (2000 psia). 1.2 This practice should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ### Document History August 1, 2011 Standard Practice for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure 1.1 This practice covers the determination of the lower and upper concentration limits of flammability of combustible vapor-oxidant mixtures at temperatures up to 200°C and initial pressures up to as... September 15, 2005 Standard Practice for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure 1.1 This practice covers the determination of the lower and upper concentration limits of flammability of combustible vapor-oxidant mixtures at temperatures up to 200°C and initial pressures up to as... ASTM E918-83(1999) April 10, 1999 Standard Practice for Determining Limits of Flammability of Chemicals at Elevated Temperature and Pressure 1.1 This practice covers the determination of the lower and upper concentration limits of flammability of combustible vapor-oxidant mixtures at temperatures up to 200°C and initial pressures up to as...	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8131459355354309, "perplexity": 2930.0034784513236}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-51/segments/1575540530857.12/warc/CC-MAIN-20191211103140-20191211131140-00391.warc.gz"}
https://campusflava.com/tag/mth101-tma-solutions/	# Tag: MTH101 TMA Solutions ## MTH101 TMA4 Questions and Solutions : Find the solution set of $\frac {x+2} {x + 1} = 1$ Find the solution set of $\frac {x+2} {x + 1} = 1$ a) $x\leqslant 2, x\geqslant -1$ b) $x \leqslant -2, x \geqslant 1$ c) $x \leqslant 2, x\geqslant 1$ d) $x \leqslant -2, x \geqslant -1$ We have given you this general course GST101 TMA1 Solutions for free for you to know how we take your TMAs serious. 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DOWNLOAD HERE Since we want to guarantee that you pass your course we have decided to give one more bonus GST101 TMA2 Solutions for free DOWNLOAD FREE NOW You can purchase MTH101 TMA Solutions at the rate of #1000 only and all of your required Courses from us kindly send us a msg on whatsapp 08039407882 SNAPSHOTS FROM HAPPY CUSTOMERS ## MTH101 TMA4 Questions and Solutions : Express 5 + 12i in a polar form, i.e in form of$Z = r( cos {\theta} + isin {\theta})$ Express 5 + 12i in a polar form, i.e in form of$Z = r( cos {\theta} + isin {\theta})$ a) Z = 13( Cos45 + isin45) b) Z = 7( Cos45 + isin45) c) Z = 15( Cos45 + isin45) d) Z = 13( Cos45 - isin45) We have given you this general course GST101 TMA1 Solutions for free for you to know how we take your TMAs serious. DOWNLOAD HERE Since we want to guarantee that you pass your course we have decided to give one more bonus GST101 TMA2 Solutions for free DOWNLOAD FREE NOW You can purchase MTH101 TMA Solutions at the rate of #1000 only and all of your required Courses from us kindly send us a msg on whatsapp 08039407882 SNAPSHOTS FROM HAPPY CUSTOMERS	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6113411784172058, "perplexity": 2059.6125211804906}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676592654.99/warc/CC-MAIN-20180721184238-20180721204238-00092.warc.gz"}
http://gmatting.blogspot.com/2010/11/	## Friday, November 26, 2010 ### CP #20 What is the number of integers from 1 to 1000 (inclusive) that are divisible by neither 11 nor by 35? (C) 2008 GMAT Club - [t]m07#14[/t] • 884 • 890 • 892 • 910 • 945 To count the number of integers from 1 to $N$ (inclusive) that are divisible by $x$ , find the value of $\frac{N}{x}$ . Use only the integer part of the resulting number. Based on the formula, the number of integers divisible by 11 is $\frac{1000}{11} = 90.9 = 90$ (even though the result could be rounded off to 91, use 90). In the same way, the number of the integers divisible by 35 is $\frac{1000}{35} = 28.57 = 28$ . Subtract the number of integers that are divisible by both 11 and 35, so that they are not counted twice. Therefore, $\frac{1000}{11} + \frac{1000}{35} - \frac{1000}{1135} = 90 + 28 - 2 = 116$ . $1000-116 = 884$ . My answer was right. Wanted to keep this here to understand why they've used 1000/ 1135. What I did was calculate 3311 and 33112 and saw that both are under 1000 and then counted 2. I should know this other method too. ### CP #19 If Ben were to lose the championship, Mike would be the winner with a probability of $\frac{1}{4}$ , and Rob - $\frac{1}{3}$ . If the probability of Ben winning is $\frac{1}{7}$ , what is the probability that either Mike or Rob will win the championship (there can be only one winner)? (C) 2008 GMAT Club - [t]m07#12[/t] • $\frac{1}{12}$ • $\frac{1}{7}$ • $\frac{1}{2}$ • $\frac{7}{12}$ • $\frac{6}{7}$ The probability of Mike or Rob winning, conditional on Ben losing, is $\frac{1}{4} + \frac{1}{3}$ or $\frac{7}{12}$ . The unconditional probability (to take into consideration the probability of Ben winning) is then $(1-\frac{1}{7}) \frac{7}{12} = \frac{6}{7} * \frac{7}{12} = \frac{1}{2}$ . I have calculated it very differently and gotten 5/14 for an answer. ### CP A contractor estimated that his 10-man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61-st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain? (C) 2008 GMAT Club - [t]m07#6[/t] • 4 • 5 • 6 • 7 • 8 • • • • The amount of work in man-hours is: $110 * 10 = 1100$ mh. After 60 days with 5 days of rain (55 net days) the crew of 10 had completed 550 mh of work, and had 550 mh more to go. Of the remaining 40 days, $x$ were raining. The last 550 mh were completed by 16 men: $(40 - x) * 16 = 550$ , and $x = 5.625$ . Round the number of rainy days down to 5 as with 6 rainy days the crew would have worked less than 550 mh and not have completed the job. ## Tuesday, November 23, 2010 ### CR update So after going through all these CR notes on the net, I tried 3 questions from OG12 (not too many left to choose from...yey!) - one of each type (S, W & A). Got the assumption question wrong, the others were right. Hmmm...going to practice slowly (i.e. identify question type, conclusion, premise(s) and imagine any linking assumptions) from my BTG account. Wish me luck! Edit: Tried a few BTG questions, and some other questions online...Hmmm...still not feeling satisfied, although I do have a methodical way of answering the questions now. sigh I should go through other question types, and then do the remaining CR questions from OG12, right? ## Monday, November 22, 2010 ### Improving first, then moving forward. Did not finish OG12. Reason is that I was going through my error log and realised I was getting certain types of questions consistently wrong in CR and SC - thought I should work on them. Posted it on GMATClub.com to see if anyone could give me some tips on improving my accuracy. For Quant, I've mainly been making silly mistakes. Also, I haven't gone through my FCs in really long so have forgotten some stuff like Compound Interest formula and how to calculate SD. Need to do that. In addition, I've been getting Triangles questions wrong - so plan on going through this series on Triangles tricks. --- Have spent most of today working on getting my basics right in CR. Will post an update soon. PS. Will take a month off from work before the GMAT because the way my work works, THIS is not going to work out! :) I've spoken to my boss and he said it'll not be an issue. So I am taking GMAT end of Jan, hopefully by 27th Jan 2011. I want to get my 800 already. :) ## Friday, November 12, 2010 Have been doing OG12 questions - 50 in one sitting. Has been going on slowly, but surely. Plan is to finish OG12 by next Thursday (6 more days). Have about half of OG left. Then I'll either work on my areas of weakness (as determined by error log analysis), or work through OG Quant & Verbal supplements (will have to buy them). Work has been slow, and idle for the last 2 weeks. I wasn't expecting it at all, so have not made full use of it :( But, things are looking up now in terms of studying so very happy :) I love my life when I study, work, dance and do my chores consistently!!! :) "Do or do not. There is no try." ## Thursday, November 4, 2010 ### CP#17 Question (from MGMAT Practice Test #1) For positive integer k, is the expression (k + 2)(k2 + 4k + 3) divisible by 4? (1) k is divisible by 8. (2) k + 1 3 is an odd integer. Solution The quadratic expression k2 + 4k + 3 can be factored to yield (k + 1)(k + 3). Thus, the expression in the question stem can be restated as (k + 1)(k + 2)(k + 3), or the product of three consecutive integers. This product will be divisible by 4 if one of two conditions are met: If k is odd, both k + 1 and k + 3 must be even, and the product (k + 1)(k + 2)(k + 3) would be divisible by 2 twice. Therefore, if k is odd, our product must be divisible by 4. If k is even, both k + 1 and k + 3 must be odd, and the product (k + 1)(k + 2)(k + 3) would be divisible by 4 only if k + 2, the only even integer among the three, were itself divisible by 4. The question might therefore be rephrased “Is k odd, OR is k + 2 divisible by 4?” Note that a ‘yes’ to either of the conditions would suffice, but to answer 'no' to the question would require a ‘no’ to both conditions. (1) SUFFICIENT: If k is divisible by 8, it must be both even and divisible by 4. If k is divisible by 4, k + 2 cannot be divisible by 4. Therefore, statement (1) yields a definitive ‘no’ to both conditions in our rephrased question; k is not odd, and k + 2 is not divisible by 4. (2) INSUFFICIENT: If k + 1 is divisible by 3, k + 1 must be an odd integer, and k an even integer. However, we do not have sufficient information to determine whether k or k + 2 is divisible by 4. Query I think the answer is D. In Statement (2), for (k+1)/3 to be an odd INTEGER, k+1 has to be divisible by 3. Also, k must be even. Therefore, k could be 2,8,... And if k is an even integer, (k + 1)(k + 2)(k + 3) will not be divisible by 4 for any of these values of k. Therefore, Statement (2) also gives us the answer. Please tell me where I'm going wrong. ### CP #16 - have not understood why not my way? Question (from MGMAT Practice Test #1) In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings? Solution We are told that 4 people have exactly 1 sibling. This would account for 2 sibling relationships (e.g. AB and CD). We are also told that 3 people have exactly 2 siblings. This would account for another 3 sibling relationships (e.g. EF, EG, and FG). Thus, there are 5 total sibling relationships in the group. Additionally, there are (7 x 6)/2 = 21 different ways to chose two people from the room. Therefore, the probability that any 2 individuals in the group are siblings is 5/21. The probability that any 2 individuals in the group are NOT siblings = 1 – 5/21 = 16/21. ## Wednesday, November 3, 2010 ### A Side Note to my Last Post Some other reasons why you might want to buy BTG questions: 1. The cost: $99 The cost till 15th November:$49! 2. BTG is giving away 3 iPads! All Free and Premium users of Practice Questions who sign up by 15th November will be eligible to win. So even if you are not sure of buying the product, atleast sign up for the free questions and you might just win an iPad! 3. 30-Day Money Back Guarantee. Seriously, it doesn't get any better than this. :) Happy Gmatting! ## Tuesday, November 2, 2010 ### Yes You Can! With the new BTG questions. Want to practice only SC questions today? Have time to do only 10? Yes you can! Have you mastered the fundamentals of Probability and want to target today's practice session only on 700+ level questions on the topic? Yes you can! After a review of your error log, do you realize that you really need to work on those Weaken type Verbal questions? Across CR and RC? Yes you can! Do you always get Integer Properties questions wrong only on the DS section? Have all day to work on it and want an (almost) unlimited supply of questions to be thrown at you till you crack it? Yes you can! Tired of going through consecutive questions in the Official Guide which are at the same difficulty level? Want a practice session where the questions thrown at you are in an adaptive format? Yes you can! Have you run out of CAT tests and want to create one of your own? Yes you can! BTG has managed to create an (almost) perfect product. If you've run out of OG questions, and even CAT tests, this product's for you. [This is an improved product from BTG which is to be released today, November 2nd. It can be found here]. Totally customizable Every practice quiz you take is totally customizable to your preferences. You can choose which section you want to target (Math or Verbal), which type of question to target (CR, RC, SC, PS, DS) and even the topic of the questions (Idioms, Weaken, Arithmetic...)! You know what else I love? You can choose the number of questions you want to answer! Have time only for 10 questions today? Your boss suddenly interrupts you during the 5th question with urgent work? No problem! You can choose to end the practice session there and see your results. And this part, my fellow readers, is what I call an absolutely brilliant feature - the difficulty level. You have a choice of below 400 questions only, all the way upto 700+ level questions. And, that's not even the most brilliant part. Have you heard of..wait for it...adaptive questions on every quiz?! This one made me super happy! A timer on the right hand side tells you how much time you've spent on the question during the quiz. Create a New Test You can choose to answer 37 Math questions, in an adaptive format. Once you've ended your session, head back to the "Practice" tab and create a session for 41 Verbal questions (adaptive mode). A brand new test has been created! :) You can also randomly pick any topics for the 2 essays from the OG, and you're all set to give a full 4 hour exam at home! A breakdown of questions on each section Math - I found the difficulty level of questions pretty reasonable, not extremely easy and not so difficult that you'd never be able to crack it in 2 minutes (under 3 minutes for the really difficult ones). Verbal - Pretty much the same as for Math... The Video Explanations A friend of mine wanted to practice some SC questions and wanted me to help him out with understanding where he was going wrong. So I called him over to practice from my Reviewer's account of BTG questions. Once he was done with the questions, I realized I didn't have to say a word to explain his mistakes to him! The video explanations did all the talking! They even taught us a few things we didn't know, such as idioms that I wouldn't have caught if I was trying to explain it to him myself. The Math explanations are clear, and I didn't find myself requiring any further explanation once the video was over. Review The review section is pretty much the same as you'd find in any other similar product. But there are two parts that stand out for me: First is the colour of the amount of time you've taken to answer the question. The colour is different according to whether you've outpaced others who answered the question, or were slower than them. The second is the flagging the questions feature. In case you want to review the question again (irrespective of whether you got it right or wrong), you can flag it. What's the point of flagging it, you ask? sly grin Prepare yourself for... Super-Customization I was feeling pretty content and happy after having customized my practice session down to the topic of questions I wanted to answer. But before I clicked on the "Start the Session" button, I saw blue text that said "Show more options". More options? Here they are: - include questions that I have already answered (after going through 700 questions, are you really going to remember them all?) - use only flagged questions (yup, include the questions you got right but should still do again) - only use questions I got wrong (for obvious reasons) And yes, you can select all 3 at the same time also. Definitely worth it if you've run out of questions to practice from, or want to customize your practice sessions exactly according to your needs (especially if you want to do this!). I had hoped such a product would come out for OG12 questions (and it's Verbal & Math supplements) so that I could practice questions from those books in an adaptive customizable style. I hope this great effort from BTG gets a similar product out for Official questions soon! :) Till then, enjoy the power and remember, with BTG questions, YES YOU CAN! PS. BTG is giving me a couple of subscriptions to this new product to give away. While I'm giving some to my friends who're also giving the GMAT soon, I might have 2 accounts left over to give away. So I'll do that on a first come first serve basis. HOWEVER, I will also snoop around and try ensuring that you don't already have an account that's been given away (I have my sources! :p). Once I'm satisfied that you do need one, I'll send you access to it! :)	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 22, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3936442732810974, "perplexity": 1092.4185064312483}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676590794.69/warc/CC-MAIN-20180719090301-20180719110301-00319.warc.gz"}
http://libros.duhnnae.com/2017/jul6/150057294359-How-well-can-we-predict-the-total-cross-section-at-the-LHC-High-Energy-Physics-Phenomenology.php	# How well can we predict the total cross section at the LHC - High Energy Physics - Phenomenology Abstract: Independently of any theory, the possibility that the large value of theTevatron cross section claimed by CDF is correct suggests that the total crosssection at the LHC may be large. Because of the experimental and theoreticaluncertainities, the best prediction is $125\pm 35$ mb. Author: P V Landshoff Source: https://arxiv.org/	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.971699595451355, "perplexity": 1015.4092012598596}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-30/segments/1563195525414.52/warc/CC-MAIN-20190717221901-20190718003901-00393.warc.gz"}
https://aviation.stackexchange.com/questions/30704/is-the-airspace-at-kgpt-class-e-or-g-when-the-tower-is-closed	# Is the airspace at KGPT class E or G when the tower is closed? I'm a bit new to airspace and I'm trying to figure out if the airspace around Gulfport-Biloxi International (KGPT) changes to class G or E when the tower closes. Looking at KGPT's airspace on a sectional, it is Class D with a note to check NOTAMs/Supplement for Class D/E (sfc) effective hrs. I've checked the chart supplements and it says Class G when the tower is closed, but the AIM leads me to think it would be Class E at 700' MSL (with Class E extensions changing to Class G) when the tower is closed since it has ASOS. Does this sound right, or am I missing something? To expand a little more on what @rbp said, the VFR Sectional Note is referring to the Class D and Class E (sfc) designations. So, when referring the the Chart Supplement, which says AIRSPACE: CLASS D svc (1200-0500Z) other times CLASS G they are referring to the Class D and Class E (sfc) specifically—just as @rbp said. Now consider what the next level of controlled airspace is when the tower is closed and the airspace over KGPT becomes Class G. It would be 700’ AGL Class E airspace. The AIM goes on to detail this (emphasis mine): Where a Class D surface area is part-time, the airspace may revert to either a Class E surface area (see paragraph 3−2−6e1) or Class G airspace. When a part–time Class D surface area changes to Class G, the surface area becomes Class G airspace up to, but not including, the overlying controlled airspace. Source: Aeronautical Information Manual (AIM), Change 1, May 26 2016, 3-2-5 Class D Airspace (13 MB PDF) And goes on to explain in Note 2 of paragraph 3-2-5 (with added emphasis): Normally, the overlying controlled airspace is the Class E transition area airspace that begins at either 700 feet AGL (charted as magenta vignette) or 1200 feet AGL (charted as blue vignette). This may be determined by consulting the applicable VFR Sectional or Terminal Area Charts. If the chart says its Class G when the tower is closed, they are talking about the surface area ("sfc" in the note), not the overlying airspace.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6413503885269165, "perplexity": 4333.619180173145}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-47/segments/1573496670535.9/warc/CC-MAIN-20191120083921-20191120111921-00457.warc.gz"}
https://www.physicsforums.com/threads/ring-of-non-uniform-charge.184821/	# Ring of Non-uniform charge 1. Sep 15, 2007 ### Luke1294 1. The problem statement, all variables and given/known data A ring of radius 'a' has a charge distribution on it that varies as $$\lambda (\theta) = \lambda_0 sin(\theta)$$, where $$\theta$$ is the angle between 'a' and the x axis. a) What is the direction of the electric field at the center of the ring? b) What is the magnitude of the field at the center of the ring? 2. Relevant equations $$d\vec{E}= \frac{k dq}{r^2}\hat{r}$$ $$\lambda (\theta) = \lambda_0 sin(\theta)$$, 3. The attempt at a solution Okay, here's what I know thus far. For a standard, uniform charge distribution, the electric field is perpendicular to the ring and follows $$\frac{kqz}{(z^2+a^2)^{3/2}}\hat{k}$$, giving us no electric field at the center of the ring, where z=0. But this is not a uniform charge distribution, so I'm not entirely sure this is going to hold true...infact, because sin has a period of 2pi, I would think that the charge on one half of the ring has an opposite charge than the other. Well, here goes nothing... I read through the derivation for the ring of charge that we went over in class and got to this point- $$E_z = \frac{k cos(\theta)}{r^2}\int dq$$ Okay, so we re-write dq as $$E_z = \frac{k cos(\theta)}{r^2}\int \lambda dl$$ Now, at this point in the derivation, we pulled lambda out because it was constant. Not so in this case. So lets leave it in there and see what we can do about that dl. Why not rewrite as $$dL = r d\theta$$? That would make things easier with the integration. We can also pull the 'r' right out of the integral because it is going to be constant. Okay, so now we have... $$E_z = \frac{k cos(\theta)}{r^2}\int \lambda d\theta$$ But we know what lambda is, so.. $$E_z = \frac{k cos(\theta)}{r^2}\int \lambda_0 sin(\theta)d \theta$$ Yank the $$\lambda_0$$ out of there...Why not put the limits of the integration on there too? Across the entire circle would be from 0 to 2pi, so... $$E_z = \frac{k cos(\theta)\lambda_0 }{r^2}\int_0^{2pi} sin(\theta)d \theta$$ Now, when I integrate $$sin \theta$$, I'm going to get zero. Making everything zero, no matter the position on the z axis. Making me think I made a mistake. I have a sneaking suspicion it involves my rewriting of dL as r dtheta, but to be honest, I am VERY fuzzy on how/why it happens. So hopefully someone can shed some light on this...feel free to give a crash course in integrating in non-rectangular coordinates. I have a very weak grasp on it at the moment. 2. Sep 15, 2007 ### Staff: Mentor Several problems here. One, you are asked to find the field smack in the middle of the ring, not somewhere along the z-axis. Two, you should be able to find the direction of the field in the center of the ring just by symmetry--no calculations needed. Three, if you are integrating with respect to theta, you can't just pull cos(theta) out from the integrand and ignore it when integrating. Four, find the proper element of charge and its field: $$dQ = \lambda dl = \lambda R d\theta = \lambda_0 \sin\theta R d\theta$$ Find the x and y components of the field from that charge element at the center of the ring and integrate around the ring. 3. Sep 15, 2007 ### Luke1294 Doc, thank you. I'll address these things one by one- 1. I was under the impression that if i designated the center of the ring to be the origin, the point x=y=Z=0 WOULD be the dead center of the ring. So that's where that came from. 2. I'm a little confused on this. The direction of field by symmetry alone...The only thing I can come up with is that it should be perpendicular to the ring itself, but to be honest, I can't defend that claim at all. 3) DOH 4) Can you give me a little more guidence as to what you mean by the x and y components from that element? I'm a little confused there. ...am going to go eat and ponder this. 4. Sep 15, 2007 ### Staff: Mentor Yes, the dead center of the ring is at that point. (Not at some off-axis point.) Why would there be a perpendicular component at all? The charge and the point of interest all lie in the same plane. See my comment above. 5. Sep 15, 2007 ### Luke1294 Okay, so upon further inspection, I had a few elements of this incredibly messed up. The theta referenced by "cos(theta)" and by the lambda expression are totally different angles. Cosine is referring to the angle between the z axis and to the circle, basically forming the side of a cone. Obviously the sin expression is referring to the angle between the radius of the ring and the z axis. I should have been much more clear there, my apologies. I will refer to the cosine angle as "phi" from here on and correct my original post. Because of that, it can stay out of the integrand. As far as the symmetry goes, this is all I have come up with- sine has a period of 2 pi. From 0-pi, the value is positive. From pi-2pi, the value is negative. We use the convention that the field points from positive to negative, so the field would be pointing in that direction across the center. As for the x and y components, the only thing I have come up with is this- I could express the X coordinate as Rsin(theta) and the Y coordinate as Rcos(theta). I don't feel that is what you meant...please bear with me here. 6. Sep 15, 2007 ### Staff: Mentor I see your point about using theta to represent two different angles, but that's not really relevant to this problem. Don't waste time correcting your original post until you realize the following: Assuming that the ring lies in the x-y plane, there is no z-component to consider. Tell me exactly what direction the field will point at the center of the ring. (Let theta = 0 be the +x direction.) I'm talking about x & y components of the field at the center. Each element of charge contributes some element of electric field at the center. I'm saying to find the x-components of the field contribution and add them up to get the total x-component of field at the center; then do the same for the y-components. (Take advantage of any symmetry, of course. ) 7. Sep 15, 2007 ### Luke1294 If my assumptions about the charge distribution are true, I believe the field will be perpendicular to the x axis throughout. Because of this, there are no components of the field flowing in the x- direction. Will be back with an answer for the Y-components, assuming I'm not way off base on that. Initially, I see that the charge would be symmetrical about the Y-axis. 8. Sep 15, 2007 ### Staff: Mentor So far, so good. Keep at it! 9. Sep 15, 2007 ### Luke1294 Haha, well, I just spent a fair amount of time setting up an integral until I realized...wait, I'm not finding the total electric field...just the magnitude at the center of the ring...whhhooops. Now this is every bit as confusing to me. I can find the force between the two. I can find the dipole moment. But the magnitude of the field through the center...hm. I know that the charge at the "top" of the ring, where theta= pi/2, is going to be $$\lambda_0$$ . I know at the "bottom" of the ring, where theta = 3pi/2, the charge is $$-\lambda_0$$. I know the distance between the two points is going to be twice the radius of the circle. This seems so simple...gah. 10. Sep 15, 2007 ### Luke1294 ....Would it just be $$2\frac{k \lambda_0}{a^2} \hat{j}$$? I found this by looking at the field from the charge at pi/2 and the field from the charge at 3pi/2 and adding them. Because one is pushing and the other is pulling, the answer is non-zero. 11. Sep 15, 2007 ### Staff: Mentor Sure you're finding the total electric field at the center. You'll need to integrate. $$\lambda_0$$ is a charge per unit length, not a point charge. It's simple, but not that simple. Does that expression even have correct units? Do as I suggested in post #2. Set up the expression for the field components and integrate. 12. Sep 15, 2007 ### Luke1294 Well as you pointed out, lambda is charge/length and I just treated it like a point charge...so no, it has the wrong units. I believe the phrase I am looking for is "rats." Electric field in the x is going to be zero. $$E_y = \int \frac{k dq}{r^2} sin \theta$$, but $$E_y = E$$, so I can ignore the theta in that expression...espically since it is the angle that the field is pointing at, DIFFERENT than the theta used in my charge distribution expression. $$E_y = \frac{k \lambda_0}{r^2} \int sin \theta d\theta$$ Symmetrical across the Y axis, so I'm going to integrate from pi/2 to 3pi/2 and double the value... $$E_y = \frac{2k \lambda_0}{r^2} \int_{\frac{\pi}{2}}^{\frac{3\pi}{2}} sin\theta d\theta$$ Right track? 13. Sep 16, 2007 ### Staff: Mentor Right. By symmetry, the x-component of the total field in the middle will be zero. OK. (Except for the sign: Realize that the field points away from the positive charge.) No. The only non-zero component of the total field in the middle will be the y-component, but you must add the y-components: $$E = \Sigma E_y$$. Without the sin(theta), you are not adding y-components. And that theta is the same theta used in the charge distribution expression! Please review what I gave as the charge element in post #2. (And put back that other sin(theta)!) Once you get the correct integrand, that will work. 14. Sep 16, 2007 ### Luke1294 Ah yes, I left out the R from the charge expression. Including the extra sin expression, I would get $$E_y = \frac{k R\lambda_0}{r^2} \int sin^2 \theta d\theta$$ Is the R from the charge expression the same as the radius of the circle? I believe it would be, but they way you wrote it as a capital R is confusing me. If it is the same, obviously that can be simplified, if not, well...then I need to figure out what radius it is referring to. 15. Sep 16, 2007 ### Staff: Mentor Yes. 16. Sep 16, 2007 ### genneth I have a question... Luke1294: have you drawn a diagram? 17. Sep 16, 2007 ### Luke1294 Initally ,yes. When I was going through the E_z steps. I'm not sure why I didn't step back and re-draw it after I figured out I was on the wrong track. Does the integrand look correct now? 18. Sep 16, 2007 ### Staff: Mentor Yes. 19. Sep 16, 2007 ### Luke1294 Okay, good. If not I think my head would explode. One last thing I'm not quite understanding... I am looking for the magnitude of the electric field at the center of the circle. Wouldn't this integral give me the field inside the entire ring? 20. Sep 16, 2007 ### Staff: Mentor Why would you think that? We are just adding up the field contributions at the center. The field anywhere within the ring would be more difficult to find; it would be a function of position.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8969619870185852, "perplexity": 472.2917345347275}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988719453.9/warc/CC-MAIN-20161020183839-00566-ip-10-171-6-4.ec2.internal.warc.gz"}
https://rupress.org/jcb/article/75/1/31/52117/Patterns-of-plasminogen-activator-production-in	Cultured normal low-passage embryo fibroblasts, from a number of species, and two untransformed clones of a Balb/3T3 line elaborate increasing amounts of plasminogen activator (PA) as they approach confluence; the low-passage cells then lose this PA activity after reaching confluence, while the 3T3 cells retain it indefinitely. Even at their peaks, however, the PA activities of the low-passage cells remain well below those of the corresponding virally or spontaneously transformed cells. The PA increases in normal cells are probably a result of PA production rather than of adsorption of secreted PA to the cell surface, or of changes in cell-associated protease inhibitors. The elaboration of PA by normal cells is dependent upon their metabolic activity, such that the level of serum supplementation and the growth phase of the culture directly influence the level of cell-associated PA observed. In addition, there may be a component of serum which exerts a negative control on PA production and which is not an acid-labile protease inhibitor. This content is only available as a PDF.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8393214344978333, "perplexity": 4636.709916577563}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-33/segments/1659882573760.75/warc/CC-MAIN-20220819191655-20220819221655-00398.warc.gz"}
http://ipnwww.in2p3.fr/A-new-leading-contribution-to-neutrinoless-double-beta-decay?date=2018-11	Accueil du site > Actualités et Faits Marquants > A new leading contribution to neutrinoless double-beta decay A new leading contribution to neutrinoless double-beta decay V. Cirigliano, W. Dekens, J. de Vries, M.L. Graesser, E. Mereghetti, S. Pastore, and U. van Kolck, Phys. Rev. Lett. 120 (2018) 202001 V. Cirigliano, W. Dekens, J. de Vries, M.L. Graesser, E. Mereghetti, S. Pastore, and U. van Kolck, Phys. Rev. Lett. 120 (2018) 202001 One of the most important advancements in modern particle physics was the observation of neutrino oscillations and the inference that neutrinos have mass. However, the origin of neutrino masses remains a mystery. They can arise from an interaction with the Higgs field that violates lepton number, makes neutrinos Majorana particles, and potentially explains the observed matter-antimatter asymmetry of the universe. This mechanism is only accessible through neutrinoless double-beta decay experiments, where two neutrons in a nucleus turn into two protons, with the emission of two electrons and no neutrinos. Nuclear physics is required for the interpretation of a non-zero signal (or lack thereof) from the enormous experimental effort which is underway around the world. Based on renormalization arguments, we have now shown that the leading contribution to neutrinoless double-beta decay, where light Majorana neutrinos are exchanged between nucleons, is not well defined without a short-range interaction. This short-range contribution is missing in all current calculations and should eventually be determined from simulations of Quantum Chromodynamics on a spacetime lattice. It can also be estimated, via chiral symmetry, from isospin-breaking observables in the two-nucleon sector. Using existing data for such an estimate, we have shown explicitly in the decay of 12Be that this new short-range contribution can be comparable to model-dependent estimates of the long-range neutrino exchange. This new leading effect could thus significantly affect the neutrino mass properties extracted from double-beta-decay experiments. Voir en ligne : Phys. Rev. Lett. 120 (2018) 202001 Institut de Physique Nucléaire Orsay - 15 rue Georges CLEMENCEAU - 91406 ORSAY (FRANCE) UMR 8608 - CNRS/IN2P3 \| Connexion SPIP \| Fil RSS du site \| Crédits et mentions légales \| Nous contacter \| Ce site est optimisé pour les navigateurs suivants Firefox, Chrome, Internet explore 9	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9143549203872681, "perplexity": 2889.206163935859}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-43/segments/1539583513686.3/warc/CC-MAIN-20181021031444-20181021052944-00376.warc.gz"}
http://gmatclub.com/forum/topic-56489.html#p402573	Find all School-related info fast with the new School-Specific MBA Forum It is currently 25 Sep 2016, 17:45 ### GMAT Club Daily Prep #### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email. Customized for You we will pick new questions that match your level based on your Timer History Track every week, we’ll send you an estimated GMAT score based on your performance Practice Pays we will pick new questions that match your level based on your Timer History # Events & Promotions ###### Events & Promotions in June Open Detailed Calendar # .... Author Message Senior Manager Joined: 30 Mar 2007 Posts: 496 Schools: Darden '15 GMAT Date: 12-07-2011 Followers: 2 Kudos [?]: 22 [0], given: 0 ### Show Tags 01 Dec 2007, 11:05 .... Last edited by Darden2010 on 24 Jun 2008, 09:39, edited 1 time in total. CEO Joined: 29 Mar 2007 Posts: 2583 Followers: 19 Kudos [?]: 386 [0], given: 0 Re: 700 - level GMATprep Question (1) [#permalink] ### Show Tags 01 Dec 2007, 12:14 Darden2010 wrote: The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent, amounting to about 72$, as compared with comparably equipped cars and trucks this year. A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to$72, as compared with comparably equipped cars and trucks this year. B. The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about $72, from that of comparably equipped models this year. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. D. Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. E. Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about$72, or four-tenths of one percent. Think u might have me here. D: eliminate. Compared to comparably... wrong. E: contrasted with comparably equipped cars... the automobile company... wrong I guess B. Manager Joined: 04 Sep 2007 Posts: 215 Followers: 1 Kudos [?]: 14 [0], given: 0 Re: 700 - level GMATprep Question (1) [#permalink] ### Show Tags 01 Dec 2007, 13:40 OlgaN wrote: Darden2010 wrote: The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent, amounting to about 72$, as compared with comparably equipped cars and trucks this year. A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to$72, as compared with comparably equipped cars and trucks this year. B. The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about $72, from that of comparably equipped models this year. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. D. Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. E. Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about$72, or four-tenths of one percent. A - compare cars and prices B - that has not clear reference C - price - cars again D -Compared to c//////////, new models.... we have to compare the same things E - Soso E - correct I disagree with Olga about E. The sentence seems awkward and on second reading implies that the car company is contrasted with the car. I'd go with B. The "that" Olga pointed out doesn't pose any ambiguity here and it clearly references to the "average price". SVP Joined: 21 Jul 2006 Posts: 1538 Followers: 10 Kudos [?]: 661 [5] , given: 1 ### Show Tags 01 Dec 2007, 13:46 5 KUDOS I would say B. A) A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to $72, as compared with comparably equipped cars and trucks this year. average price is compared to cars and trucks b) The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about$72, from that of comparably equipped models this year "that" is also the average price. Therefore, the comparison is appropriate. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. average price is compared to cars and tracks d) Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. models are compared to the automobile company e) Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about $72, or four-tenths of one percent cars and trucks are compared or contrasted with the automobile company hope this helps SVP Joined: 28 Dec 2005 Posts: 1575 Followers: 3 Kudos [?]: 131 [0], given: 2 [#permalink] ### Show Tags 01 Dec 2007, 14:35 i like B as well. E is just nasty Director Joined: 13 Dec 2006 Posts: 518 Location: Indonesia Followers: 6 Kudos [?]: 192 [0], given: 0 [#permalink] ### Show Tags 01 Dec 2007, 17:25 tarek99 wrote: I would say B. A) A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to$72, as compared with comparably equipped cars and trucks this year. average price is compared to cars and trucks b) The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about $72, from that of comparably equipped models this year "that" is also the average price. Therefore, the comparison is appropriate. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. average price is compared to cars and tracks d) Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. models are compared to the automobile company e) Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about$72, or four-tenths of one percent cars and trucks are compared or contrasted with the automobile company hope this helps Good explanation- B for me Amar Director Joined: 09 Aug 2006 Posts: 763 Followers: 1 Kudos [?]: 168 [1] , given: 0 Re: 700 - level GMATprep Question (1) [#permalink] ### Show Tags 02 Dec 2007, 03:15 1 KUDOS Darden2010 wrote: The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent, amounting to about 72$, as compared with comparably equipped cars and trucks this year. A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to$72, as compared with comparably equipped cars and trucks this year. B. The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about $72, from that of comparably equipped models this year. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. D. Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. E. Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about$72, or four-tenths of one percent. Pick B. Cannot compare price with cars. Eliminate A. 'decrease' and 'below' are redundant in C. Eliminate. 'Compared to comparably equipped models' is awkward. 'decrease' and 'less' are redundant in D. Eliminate. We are not contrasting cars with automobile company' Eliminate E. Director Joined: 26 Mar 2006 Posts: 647 Followers: 1 Kudos [?]: 24 [0], given: 0 Re: 700 - level GMATprep Question (1) [#permalink] ### Show Tags 03 Dec 2007, 02:21 Darden2010 wrote: The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent, amounting to about 72$, as compared with comparably equipped cars and trucks this year. A. The automobile company announced that the average price of next year’s models would decrease four-tenths of one percent amounting to$72, as compared with comparably equipped cars and trucks this year. B. The automobile company announced that the average price of next year’s cars and trucks would decrease four-tenths of one percent, or about $72, from that of comparably equipped models this year. C. The automobile company announced that there would be a decrease of four-tenths of one percent in next year’s models’ average price, or about 72$, below this year’s comparably equipped cars and trucks. D. Compared to comparably equipped models this year, the automobile company announced that the average price of next year’s cars and trucks would decrease about 72$, less by four tenths of one percent. E. Contrasted with comparably equipped cars and trucks of this year, the automobile company announced that the average price of next year’s models would decrease about$72, or four-tenths of one percent. Looks like 'B'.. Re: 700 - level GMATprep Question (1) [#permalink] 03 Dec 2007, 02:21 Display posts from previous: Sort by	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.15288452804088593, "perplexity": 10141.390071915297}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738660467.49/warc/CC-MAIN-20160924173740-00014-ip-10-143-35-109.ec2.internal.warc.gz"}
https://www.physicsforums.com/threads/orthogonal-complements-of-complex-and-continuous-function-subspaces.562266/	# Homework Help: Orthogonal Complements of complex and continuous function subspaces 1. Dec 22, 2011 ### unquantified 1. The problem statement, all variables and given/known data I'm having a tough time figuring out just how to get the orthogonal complement of a space. The provlem gives two separate spaces: 1) span{(1,0,i,1),(0,1,1,-i)}, 2) All constant functions in V over the interval [a,b] 2. Relevant equations I know that for a subspace W of an inner product space, the orthogonal complement is defined as: W_perp = {vectors in v$\in$V: <v,w> = 0 for all w $\in$ W} <v,w> is the standard dot product between two vectors; In the case of constant functions, the dot product is $\int$f(x)g(x)dx; 3. The attempt at a solution 1) I tried putting it in matrix form: [1 0 i 1] [0 1 1 -i] but don't know how to row reduce with complex variables. I actually don' think the matrix needs to be simplified more than it is, but still don't know how to plug in to get two orthogonal vectors (I would like the result to be an orthogonal set) 2) I don't even know where to start ... the book doesn't cover inner products of functions much , let alone how to find the orthogonal complement of them. Last edited: Dec 22, 2011 2. Dec 22, 2011 ### Dick You doing a pretty good job of ignoring any information in your "Relevant equations" section. If you don't do that the second question should be pretty easy. You can factor a constant function outside of the integral. For the first one you should remember, if you weren't told, that <u,v> for complex vectors involves taking a complex conjugate of one of the vectors. Suppose v=(A,B,C,D). Then what two equations do you have to solve for the four unknowns A, B, C and D? 3. Dec 22, 2011 ### unquantified So, for the first part, the orthogonal complement would just be all f(x) where by ∫f(x) = 0 over the given interval [a,b]? As for the second, I'm not quite sure what you mean. If I have those equations, and let x =[x_1, x_2, x_3, x_4] be my unknowns, I have: [x_1,x_2,x_3,x_4] = x_3[-i, -1, 1, 0] + x_4[-1,i,0,1] Is that correct? I would then plug in x_3=1 and then x_4=1 to each of those vectors to get my orthogonal complement. 4. Dec 23, 2011 ### Dick That's the answer to the first one alright. For the second one, take w=(w1,w2,w3,w4) to be your unknown vector in the orthogonal complement. Now since w need to be orthogonal to the span{(1,0,i,1),(0,1,1,-i)}, it has to be orthogonal to v1=(1,0,i,1) and v2=(0,1,1,-i). So you must have <v1,w>=0 and <v2,w>=0. What do those equations look like when you write them out in terms of w1, w2, w3 and w4?	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9141865968704224, "perplexity": 573.9570055026123}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794865595.47/warc/CC-MAIN-20180523102355-20180523122355-00625.warc.gz"}
https://researchoutput.ncku.edu.tw/zh/publications/development-of-an-arrhythmia-monitoring-system-and-human-study	# Development of an Arrhythmia Monitoring System and Human Study Shuenn Yuh Lee, Peng Wei Huang, Ming Chun Liang, Jia Hua Hong, Ju Yi Chen 9 引文斯高帕斯（Scopus） ## 摘要 Electrocardiography (ECG) is a fundamental method not only commonly used in the hospital for clinical requirement but also widely adopted in home and personal healthcare systems to obtain the electrical activity of the heart. An arrhythmia monitoring system is proposed and used in a clinical trial. The proposed system has three parts. The first is a high-resolution, low-power analog front-end circuit for implementing bio-signal sensing circuits. This part is developed with a chopper-based pre-amplifier and a high-pass sigma-delta modulator. The features of the circuits are low complexity, high resolution, and low power consumption. The second part is a digital signal processor with a decimation filter and a universal asynchronous receiver/transmitter package generator. The last part is used to realize a software interface on smartphone for ECG signal recording, display, and classification. A wavelet-based classification method is also proposed to classify the rhythm. The chip used in the system is fabricated through the 0.18 $\boldsymbol {\mu }\text{m}$ standard complementary metal-oxide-semiconductor process, and the operation voltage is 1.2 V. The classification algorithm is verified with data from the MIT/BIH arrhythmia database. The accuracy of beat detection and arrhythmia classification is 99.4% and 95.83%, respectively. Eight patients are enrolled in a human study to verify the performance of the proposed arrhythmia monitoring system. Results show that the system can acquire and classify ECG signals. 原文 English 8490696 442-451 10 IEEE Transactions on Consumer Electronics 64 4 https://doi.org/10.1109/TCE.2018.2875799 Published - 2018 11月 • 媒體技術 • 電氣與電子工程	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4662529528141022, "perplexity": 3521.9756429497643}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296943704.21/warc/CC-MAIN-20230321162614-20230321192614-00054.warc.gz"}
https://undergroundmathematics.org/quadratics	## How do different representations help us to understand quadratics? ### Key questions 1. 1 How are the graphical and algebraic representations of quadratics connected? 2. 2 What do we mean by the roots of a quadratic equation and how can we find them? 3. 3 What is the discriminant of a quadratic, and what can it tell us? No resources found. Title Lines Key questions Related ideas No resources found. This resource is in your collection #### Review questions Click for information about review questions Title Lines Key questions Related ideas No questions found. This resource is in your collection #### Introducing... Resource type Title #### Developing... Resource type Title Fluency exercise Inequalities for some occasions Fluency exercise Pick a card... Package of problems Discriminating Package of problems GeoGebra constructions... quadratic edition Package of problems Irrational roots Package of problems Name that graph Package of problems Paired parabolas Package of problems Which parabola? Food for thought Parabella Bigger picture Parabolic mirrors Resource in action Discriminating - teacher support #### Review questions Title Ref Can we find both roots if one is double the other? R6638 Can we find the midpoint of a chord of this parabola? R8045 Can we find the tangents to a circle from a point? R6804 Can we fit a quadratic to this given data? R8775 Can we prove this inequality involving two square roots? R7533 Can we show $(b^2 - 2ac)x^2 + 4(a + c)x = 8$ always has real roots? R8812 Can we solve $12/(x-3) < x+1$? R7035 Can we solve $\sqrt{3-3x} - \sqrt{2-x} = 1$? R7485 Can we solve $nx^2+2x\sqrt{pn^2+q}+rn+s=0$? R6246 Can we solve the simultaneous equations $x + y + \sqrt{xy} = 39$ and $x^2 + y^2 + xy = 741$? R5682 Can we solve these simultaneous equations that involve reciprocals? R8128 Can we solve these simultaneous equations, both of degree two? R7520 Can we solve these simultaneous equations, one linear, one quadratic? R6429 Can we solve this inequality with three square roots? R6387 For what values of $k$ is $x^2 + 6kx +144$ always positive? R6526 Given the minimum point, what's this parabola's equation? R6756 Given two simultaneous equations of degree two, can we solve them? R7588 How do we solve $x + 3\sqrt{x} − 1/2 = 0$? R6215 How do we increase the roots of a quadratic equation by $1$? R6712 How do we solve an equation containing three square roots? R5847 How fast are these particles sliding when they pass? R6864 If $2y = a^x + a^{-x}$, can we find $a^x$? R6816 If $7 - px - x^2 = 16 - (q + x)^2$, what are $p$ and $q$? R9724 If we know two values satisfying a quadratic, can we find the quadratic? R7972 Into how many regions do these parabolas divide the plane? R8781 What does the curve $x^4-y^2=y+1$ look like? R8855 When are the coefficients of a quadratic equal to its roots? R7350 When are the roots for $x^2-bx+c=0$ real and positive? R5138 When are these quadratic inequalities true together? R9989 When can this equation involving algebraic fractions hold? R8407 When do these simultaneous equations have no real solutions? R9658 When does $(p+1)x^2+4px+9=0$ have a repeated root? R7455 When does $x^2 + ax + a = 1$ have distinct real roots? R9659 When does $x^2+(3k-7)x+(2k+6)=0$ have real roots? R6828 When does $x^2-4x-1=2k(x-5)$ have equal roots? R5316 When does $x^4=(x-c)^2$ have four real roots? R9546 When does $y=kx$ intersect the parabola $y=(x-1)^2$? R9614 When does $y=mx-5$ intersect $y=x^2-1$ twice? R5287 When is $12x^2+7x-10$ negative? R5059 When is this line a tangent to this parabola? R7328 Where does $y = px^2 + 8x + p - 6$ cross the $x$-axis? R9742	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8421213626861572, "perplexity": 2975.778534573869}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886105712.28/warc/CC-MAIN-20170819182059-20170819202059-00125.warc.gz"}
https://math.stackexchange.com/questions/3509582/circle-envelope-tangent-in-another-circle/3545910	# circle envelope tangent in another circle As the picture shows, One big circle ,$$(0,0)$$ ,radius=R, there is a small circle in it, $$(m,0)$$ ,radius=r . G is on the big circle. From G ,we can do two tangent lines about the small circle. Get the points of intersection E and F. line EF has a envelope about G , which seem like a circle. How to prove it? Since calculating it requires much effort. By picking special points,I get the radius of envelope circle is $$\frac{R \left(m^4-2 m^2 \left(r^2+R^2\right)-2 r^2 R^2+R^4\right)}{\left(m^2-R^2\right)^2}$$ and the circle center $$\left(\frac{1}{2} \left(\frac{R \left(-m^2+2 m R+2 r^2-R^2\right)}{(R-m)^2}-\frac{R \left(-m^2-2 m R+2 r^2-R^2\right)}{(m+R)^2}\right),0\right)$$ • Your formulas can be simplified : for the radius into $R \left(1-2r^2 \dfrac{m^2+R^2}{(R^2-m^2)^2}\right)$ and even more for the abscissa of the center which can be written : $4m\dfrac{R^2r^2}{(R^2-m^2)^2}$ – Jean Marie Jan 15 at 23:11 • I have been working a lot on your issue without real success. Could we share our advances ? Moreover, could you say something about the origin of this problem ? – Jean Marie Jan 19 at 21:06 • @JeanMarie the origin of this problem is that: prove the envelope is a circle as well as use ruler-and-compass construction to make the tangent point of EF and circle. – wuyudi Jan 20 at 3:25 • From the references in the link from @brainjam: This question is very similar to the one Poncelet started with – Jan-Magnus Økland Feb 14 at 9:40 Here is an analytic geometry solution : We can assume without loss of generality that $$R=1$$, i.e., we work inside the unit circle. Therefore, we have the following condition : $$0 < m <1$$. Let us introduce some notations. Let $$B$$ be the second intersection of line $$GC$$ with the unit circle. Let $$a$$ be the polar angle of point $$G$$ (i.e., oriented angle between positive $$x$$-axis and $$AG$$). Let $$b$$ be the polar angle of $$B$$ (i.e., oriented angle between positive $$x$$-axis and $$AB$$). Let $$\theta$$ be the angle of line $$GE$$ with line $$GB$$ (equal to the angle between $$GB$$ and $$GF$$). We will use a certain number of trigonometric formulas. An extensive and well structured list of those can be found here. Fig. 1: $$G(\cos a,\sin a)$$, $$B(\cos b,\sin b)$$, and $$C(m,0)$$, center of the small circle with radius $$r$$. The circle to which lines $$EF$$ are all assumed to be tangent is in red. Let us look for relationships between angles $$a,b$$ and $$\theta$$ and lengths $$m$$ and $$r$$. • a) The fact that $$GE$$ and $$GF$$ are tangent to the small circle is expressed by the following relationship : $$\sin \theta = \dfrac{r}{GC}$$ which is equivalent to : $$(\sin \theta)^2 = \dfrac{r^2}{GC^2}= \dfrac{r^2}{(\cos a - m)^2+(\sin a - 0)^2}=\dfrac{r^2}{1 - 2m \cos a +m^2}\tag{1}$$ • b) The angle between $$AE$$ and $$AB$$ is $$2 \theta$$ by central angle theorem. The same for the angle between $$AB$$ and $$AF$$. Let $$I$$ be the intersection point of line $$AB$$ and line $$EF$$ ; triangle $$EAF$$ being isosceles, line segment $$AI$$ is orthogonal to $$EF$$, implying that its algebraic measure ("signed distance") is $$AI=\cos(2 \theta)$$ (possibly negative). Therefore, straight line $$EF$$ whose normal vector is $$\vec{AB} = \binom{\cos b}{\sin b}$$ has equation : $$x \cos b + y \sin b = \cos 2 \theta \tag{2}$$ Using relationship $$\cos 2 \theta=1-2 \sin^2 \theta$$ with formula (1) : $$x \cos b + y \sin b = 1-\dfrac{2 r^2}{1 - 2m \cos a +m^2}\tag{3}$$ • c) Let us, finally, express that $$G, C$$ and $$B$$ are aligned. This relationship, written under the form (see http://mathworld.wolfram.com/Collinear.html) : $$\begin{vmatrix}m &\cos a &\cos b\\0 & \sin a&\sin b\\1&1&1\end{vmatrix}=0\tag{4}$$ i.e., $$m=\dfrac{\sin(a-b)}{\sin a - \sin b}$$ $$\iff \ \ m=\dfrac{\color{red}{2 \sin(\tfrac12(b-a))}\cos(\tfrac12(b-a))}{\color{red}{2 \sin(\tfrac12(b-a))}\cos(\tfrac12(b+a))}=\dfrac{1+\tan(a/2) \ \tan(b/2)}{1-\tan(a/2) \ \tan(b/2)}$$ yielding the rather unexpected following condition : $$\tan(a/2) \ \tan(b/2)=k \ \ \text{where} \ \ k:=\dfrac{m-1}{m+1}\tag{5}$$ from which we deduce (using a "tangent half-angle formula" and setting : $$t:=\tan(b/2)$$ that : $$\cos a=\dfrac{1-\tan(a/2)^2}{1+\tan(a/2)^2}=\dfrac{1-\left(\tfrac{k}{t}\right)^2}{1+\left(\tfrac{k}{t}\right)^2}=\dfrac{t^2-k^2}{t^2+k^2}\tag{6}$$ Plugging (6) into formula (3), we get for the RHS of (3) after some algebraic transformations : $$\cos 2 \theta=1-\dfrac{2r^2(t^2(m+1)^2+(m-1)^2)}{(m^2-1)^2(1+t^2)}$$ Using once again tangent half-angle formulas, we can now express the equation of straight line $$EF$$ under the following parametric form in variable $$t$$ : $$x \dfrac{1-t^2}{1+t^2} + y \dfrac{2t}{1+t^2} - 1+\dfrac{2r^2(t^2(m+1)^2+(m-1)^2)}{(m^2-1)^2(1+t^2)}=0.\tag{7}$$ It remains to establish that the distance $$d$$ of the point with coordinates $$C'(x_0,y_0)=\left(4m\dfrac{r^2}{(1-m^2)^2},0\right)\tag{8}$$ (would-be center of envelope circle) to straight line $$EF$$ is constant (i.e., is independent from $$t$$). This distance, obtained (see http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html) by replacing $$(x,y)$$ in the Left Hand Side of equation (7) by the coordinates $$(x_0,y_0)$$ of $$C'$$ given by (8) $$d=(2r^2(1+m^2) - (m^2 - 1)^2)/(m^2 - 1)^2\tag{9}$$ is indeed independent from parameter $$t$$ ; moreover it is (up to its sign) the awaited expression (I have used a Computer Algebra System to obtain this expression of $$d$$). Remarks : 1) It is possible to characterize the tangent point of $$EF$$ on the (red) envelope circle, following the method outlined by @Jan-Magnus Økland in comments following this answer. 2) About a possible more (synthetic) geometry solution. I just discovered in this paper dealing with "exponential pencils of conics" that there is so-called "conjugate conic" of the first circle vs. the second circle (see Theorem 2.5 page 4). But I am not sure it will permit a new solution. • In maxima CAS with the $r$ you dropped in (7) back in l:x((1-t^2)/(1+t^2))+y(2t/(1+t^2))+(((2m^2+4m+2)r^2-m^4+2m^2-1)t^2+(2m^2-4m+2)r^2-m^4+2m^2-1)/((m^4-2m^2+1)t^2+m^4-2m^2+1); Then the envelope is given by solve([l,diff(l,t)],[x,y]); [[x=(((2m^2+4m+2)r^2-m^4+2m^2-1)t^2+((-2m^2)+4m-2)r^2+m^4-2m^2+1)/((m^4-2m^2+1)t^2+m^4-2m^2+1),y=-(((4m^2+4)r^2-2m^4+4m^2-2)t)/((m^4-2m^2+1)t^2+m^4-2m^2+1)]] – Jan-Magnus Økland Jan 27 at 9:41 • Then the implicitization in M2: R=QQ[m,r] S=R[s,t,x,y,z] I=ideal(x-(((2m^2+4m+2)r^2-m^4+2m^2-1)t^2+(((-2m^2)+4m-2)r^2+m^4-2m^2+1)s^2),y+(((4m^2+4)r^2-2m^4+4m^2-2)st),z-((m^4-2m^2+1)t^2+(m^4-2m^2+1)s^2)) gens gb I -- (4r^4+((-4m^2)-4)r^2+m^4-2m^2+1)z^2 +8mr^2xz+((-m^4)+2m^2-1)y^2+((-m^4)+2m^2-1)x^2 – Jan-Magnus Økland Jan 27 at 9:41 • $z$ is just there to eliminate the fractions. Setting $z=1$ gives the correct answer. – Jan-Magnus Økland Jan 27 at 10:08 • @JeanMarie: I don't (yet?) have a better solution, synthetic or otherwise, but I have an possibly-useful observation: let $e$ and $f$ be the distances from $E$ and $F$ to the points where $\overline{GE}$ and $\overline{GF}$ touch $\bigcirc C$, and let $e'$ and $f'$ be the distances from $E$ and $F$ to the point where $\overline{EF}$ touches the target circle. Then $$\frac{e}{f}=\frac{e'}{f'}$$ – Blue Feb 7 at 19:07 • @JeanMarie I don't think that the "conjugate conic" approach will be fruitful. That's because the red circle is coaxal with the big and small circles, so it is a linear combination of the two (i.e. its equation is a weighted sum of the equations of the other 2). See more context in math.stackexchange.com/a/3545910/1257. If the problem is generalized projectively the red conic will be in the pencil generated by the first two conics. – brainjam Feb 13 at 23:32 The expository paper Poncelet's theorem by András Hraskó very nicely treats this problem and its relation to Poncelet's Closure Theorem. In the OP diagram call the big and little circles $$e$$ and $$a$$ respectively, and the red circle $$c$$. (this corresponds to the labels in the paper, see Figures 1,4,5). Poncelet's Theorem is concerned with scenarios such as Figures 1 and 4, where a polygon is inscribed in $$e$$ such that the edges touch $$a$$. But the paper speculates that Poncelet studied that situation of an inscribed triangle where one of the sides does not touch $$a$$, and found that the non-touching side generates the envelope of a circle $$c$$ (Figure 5). As @Blue has noted in the comments, $$c$$ is coaxal with the pair $$a$$ and $$e$$. I leave the details to the paper, but can't resist quoting this: Poncelet's General Theorem: Let $$e$$ be a circle of a non-intersecting pencil and let $$a_1,a_2,\ldots,a_n$$ be (not necessarily different) oriented circles in the interior of $$e$$ that belong to the same pencil. Starting at an arbitrary point $$A_0$$ of the circle $$e$$, the points $$A_1,A_2,\ldots,A_n$$ are constructed on the same circle, such that the lines $$A_0A_1, A_1A_2, \ldots, A_{n-1}A_n$$ touch the circles $$a_1,a_2,\ldots, a_n$$, respectively, in the appropriate direction. It may happen that at the end of the construction, we get back to the starting point, that is, $$A_n=A_0$$. The theorem states that in that case, we will always get back to the starting point in the $$n$$-th step, whichever point of $$e$$ we start from. We do not even need to take care to draw the tangents to the circles in a fixed order. The case of $$a_1=a_2=\cdots=a_n=a$$ gives the classic Poncelet's Closure Theorem. The case $$a_1=a_3=a, a_2=c$$ relates to the OP. • For more on Poncelet's General Theorem, see Poncelet’s porism: a long story of renewed discoveries, I and II by Andrea Del Centina – Jan-Magnus Økland Feb 18 at 9:51 • @Jan-MagnusØkland, thanks for this reference. It also suggests an answer to a projectively dual problem. See math.stackexchange.com/a/3560237/1257 – brainjam Feb 26 at 17:56	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 97, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9081491231918335, "perplexity": 308.3536583789576}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347419639.53/warc/CC-MAIN-20200601211310-20200602001310-00396.warc.gz"}
https://www.jiskha.com/questions/510647/my-sister-has-no-websites-to-go-to-for-fun-she-is-10-so-what-do-you-suggest	# computer fun My sister has no websites to go to for fun.She is 10 so what do you suggest? 1. 👍 0 2. 👎 0 3. 👁 174 1. 👍 0 2. 👎 0 👩‍🏫 Ms. Sue ## Similar Questions 1. ### english My trip to the dentist was not fun and was not fast either. not fun, but not fast. neither fun nor fast. 2. ### Math Kim and her sister play a game at the end of the game cam has 65 points at her sister has -12 points what is the difference between Kim store and her sister score 3. ### english Identify the correct sentence. A. Where is the necklace from your sister and the earrings from your cousin? B. Where are the necklace from your sister and the earrings from your cousin? C. Where are the necklace from your sister 4. ### Chemistry Now consider just the second sentence of the multistep word problem. Sentence 2: If four times the brother's age is subtracted from three times the sister's age, the difference is 16. Give an equation that represents this 1. ### math Deandre is a software salesman. His base salary is $1900 , and he makes an additional$50 for every copy of English is Fun he sells. Let P represent his total pay (in dollars), and let N represent the number of copies of English 2. ### english In which sentence is the underlined phrase a prepositional phrase functioning as an adjective? She went to boarding school in Coventry. My sister was born in Chicago. Her grades gave my sister a place in the top rank of her class. 3. ### Math Currently you have $80 and your sister has$145. You decide to save $6 of your allowen e each week, while your sister spends her whole allowance plus$7 a week. How long will it be before you have as much money as your sister? 4. ### Trigonometry Let's solve this fun trigonometric fun math problem! 1.) SEC²X-1/SIN²X 1. ### math Tyrone has $60 and his sister has$135. Both get an allowance of $5 each week. Tyrone decides to save his entire allowance, but his sister spends all of hers each week plus an additional$10 each week. After how many weeks will 2. ### Math Mark weighs 74 pounds. Together, he and his sister weigh six pounds more than three times the weight of his sister. What is the weight of Mark's sister? would it be 74=3(w)+6 3. ### psychology You are likely to be seeing regression when maria, the first born, reacts to the birth of her new sister by A pleading with mom to let her help with the baby B suddenly having ''accidents'' well after she's been potty trained C 4. ### Math 6. Tikka made bamboo fishing poles for her sister and herself. She used\frac{2}{3} 2 3 of a 10-foot stick of bamboo for her pole and the rest for her sister's. How long is her sister's fishing pole?	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.38613182306289673, "perplexity": 5779.351070832657}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600400201826.20/warc/CC-MAIN-20200921143722-20200921173722-00030.warc.gz"}
https://answers.ros.org/answers/16651/revisions/	# Revision history [back] A couple of things: 1) I tried to run in simulation with similar parameters, I'll post them at the bottom of this post, and things worked for me. 2) Its not clear from the video you posted whether or not the local costmap's obstacles are being updated properly. This tutorial shows how to display navigation-relevant information in rviz. Specifically, I'd really like to know whether move_base/local_costmap/obstacles shows anything. Here are the params I used in stage: ### costmap_common_params.yaml #Set the tolerance we're willing to have for tf transforms transform_tolerance: 0.3 #Obstacle marking parameters obstacle_range: 2.5 max_obstacle_height: 2.0 raytrace_range: 3.0 #The footprint of the robot and associated padding footprint: [[-0.325, -0.325], [-0.325, 0.325], [0.325, 0.325], [0.46, 0.0], [0.325, -0.325]] #Cost function parameters cost_scaling_factor: 10.0 #The cost at which a cell is considered an obstacle when a map is read from the map_server lethal_cost_threshold: 100 ### local_costmap_params.yaml local_costmap: #Set the global and robot frames for the costmap global_frame: map #Set the update and publish frequency of the costmap update_frequency: 5.0 publish_frequency: 2.0 static_map: true rolling_window: false ### global_costmap_params.yaml global_costmap: #Set the global and robot frames for the costmap global_frame: /map #Set the update and publish frequency of the costmap update_frequency: 5.0 publish_frequency: 0.0 #We'll use a map served by the map_server to initialize this costmap static_map: true rolling_window: false ### base_local_planner_params.yaml TrajectoryPlannerROS: #Set the acceleration limits of the robot acc_lim_th: 4.0 acc_lim_x: 3.7 acc_lim_y: 3.5 #Set the velocity limits of the robot max_vel_x: 0.2 min_vel_x: 0.05 max_rotational_vel: 0.3 min_in_place_rotational_vel: 0.05 #The velocity the robot will command when trying to escape from a stuck situation escape_vel: -0.1 #For this example, we'll use a holonomic robot holonomic_robot: true #Since we're using a holonomic robot, we'll set the set of y velocities it will sample y_vels: [-0.3, -0.1, 0.1, 0.3] #Set the tolerance on achieving a goal xy_goal_tolerance: 0.1 yaw_goal_tolerance: 0.05 #We'll configure how long and with what granularity we'll forward simulate trajectories sim_time: 1.7 sim_granularity: 0.025 vx_samples: 3 vtheta_samples: 20 #Parameters for scoring trajectories goal_distance_bias: 0.8 path_distance_bias: 0.6 occdist_scale: 0.01	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7095690369606018, "perplexity": 12299.883899150924}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656103347800.25/warc/CC-MAIN-20220628020322-20220628050322-00767.warc.gz"}
http://mathematica.stackexchange.com/questions/19082/efficient-way-of-setting-up-a-rule/19104	# Efficient way of setting up a rule I tried to define a simple rule defining how λ acts on ψ[n]: myrule1 = λ ψ[n_] -> α[n + 1] ψ[n + 1]; The result I get is correct provided there's just one λ on the RHS of ψ[n]. For instance: λ^2 ψ[n] //. myrule1 isn't computed at all. On the other hand, if I do it step by step: λ α[1 + n] ψ[1 + n] /. myrule1 I get the correct result. I tried to define a new rule: myrule2 = λ^m_ ψ[n_] -> α[n + 1] λ^(m - 1) ψ[n + 1]; but it doesn't work. Since the recursive method seemed to work, I created a function which multiplies ψ[m] by λ n times: timesλ[n_] := Nest[Times[λ, #] /. myrule1 &, ψ[m], n] & But this is a very crude way of solving this problem. Do you have any other ideas? - Could augment with a second form \[Lambda]^(j_ /; IntegerQ[j] && j >= 1) \[Psi][n_] -> \[Alpha][ n + j] \[Psi][n + j] – Daniel Lichtblau Feb 5 '13 at 15:51 Thanks! The rule you suggest is incorrect, but the idea is ok. – Gregory Rut Feb 6 '13 at 12:13 Ah, yes, I missed the need for a product. I think the @m_goldberg variation sounds better... – Daniel Lichtblau Feb 6 '13 at 14:47 If you look at the full form versions of λ ψ[n] and λ^k ψ[n] λ ψ[n] // FullForm Times[λ, ψ[n]] λ^k ψ[n] // FullForm Times[Power[λ, k],ψ[n]] you see that the second expression can't match your rule because it contains Power. Therefore, as Daniel Lichtblau suggests, you need to have two rules. rules = {λ ψ[n_] -> α[1 + n] ψ[1 + n], λ^j_ ψ[n_] -> Product[α[s], {s, n + 1, n + j}] ψ[j + n]}; Now you can get both λ ψ[n] /. rules α[1 + n] ψ[1 + n] and λ^k ψ[n] /. rules Product[α[s], {s, n + 1, n + k}] ψ[k + n] - Looks good, thanks! It is weird that myrule2 didn't bring any output, it 'almost' works on another pc (one λ is left because of different Head on RHS, as you mentioned). – Gregory Rut Feb 6 '13 at 12:26 It appears that Gregory is not following this thread but I think you may learn something from the answer I just posted. – Mr.Wizard Mar 5 '13 at 23:38 ## Preliminary This can be done with a single rule and an Optional pattern because Power has the attribute OneIdentity. As the documentation states: The fact that Times has attribute OneIdentity allows a pattern like n_. x_ to match x. Observe: {2^y, 3} /. a_Integer^b_. :> {a, b} {{2, y}, {3, 1}} (Power has an internal default of one.) Note also that I use RuleDelayed (short form :>) and not Rule; this is necessary to correctly localize named patterns on the right hand side of the rule. With this knowledge we can now adjust your rule2; with this formulation we will need ReplaceRepeated (short form //.): rule = λ^m_. ψ[n_] :> α[n + 1] λ^(m - 1) ψ[n + 1]; λ^3 ψ[n] //. rule α[1 + n] α[2 + n] α[3 + n] ψ[3 + n] Or if you prefer, the Product formulation: rule2 = λ^j_. ψ[n_] :> Product[α[n + s], {s, j}] ψ[j + n]; λ ψ[n] /. rule2 λ^2 ψ[n] /. rule2 α[1 + n] ψ[1 + n] α[1 + n] α[2 + n] ψ[2 + n] - Thanks, that's a very nice solution. – Gregory Rut Sep 13 '13 at 18:52 @Gregory Welcome back to the site. I'm glad you found this helpful even now. :-) – Mr.Wizard Sep 15 '13 at 17:08	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4513421058654785, "perplexity": 7596.846492495825}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-14/segments/1427131299339.12/warc/CC-MAIN-20150323172139-00194-ip-10-168-14-71.ec2.internal.warc.gz"}
https://economics.stackexchange.com/questions/19643/arrows-impossibility-theorem	# Arrow's impossibility theorem In social choice theory, Arrow's impossibility theorem, the general possibility theorem or Arrow's paradox is an impossibility theorem stating that when voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide (complete and transitive) ranking while also meeting a specified set of criteria: unrestricted domain, non-dictatorship, Pareto efficiency and independence of irrelevant alternatives (IIA) So, I'm looking for an example where the preferences satisfy unrestricted domain, non dictatorship, IIA and is an ordering, but not meet the Pareto criteria. Let the set of alternatives be $A = \left\{a_1,a_2,...,a_k\right\}$. Let the number of players be $n$. Let the set of preference orderings over $A$ be $\mathcal{P}$. Then the set of preference profiles is the Cartesian product $$\mathcal{P}^n = \times_{i=1}^{n} \mathcal{P}.$$ Let us denote the preference ordering $$a_1 \succ a_2 \succ ... \succ a_k$$ by $p^$. Define the Social Choice Function $F$ by $$\forall p \in \mathcal{P}^n: F(p) = p^.$$ This SCF $F$ clearly has universal domain, is not a dictatorship, and is also independent of irrelevant alternatives. (Or any alternatives for that matter.) • Hey, thanks. But I am unable to understand the functioning of this social choice rule. How is it not a dictatorship and how does it not meet Pareto criteria? – LUCIFER Dec 10 '17 at 1:07 • @LUCIFER Could you please define what you think a dictatorship SCF is? And can you please also define the Pareto property for SCFs? – Giskard Dec 10 '17 at 7:28 • Dictatorship is when there is an individual such that if he prefers x over y, then so does the society irrespective of what the society feels. – LUCIFER Dec 10 '17 at 21:00 • And Pareto property is that if all individuals prefer x over y, then so should the society. It is about how society preserves total agreement. – LUCIFER Dec 10 '17 at 21:01 • @LUCIFER If you understand these then surely you see how my SCF fulfills neither condition. I will improve notation a bit. – Giskard Dec 10 '17 at 21:16 The Pareto criterion has two effects: It guarantees that every ranking can occur as a social ranking and it connects social rankings to individual rankings. If one drops the Pareto criterion but keeps the assumption that every social ranking is possible, one obtains a generalization in which every SCG corresponds to a dictatorship or an anti-dictatorship in which the social ranking is exactly opposite to the ranking of a specific individual, an anti-dictator. This is known as Wilson's theorem, originally from: Wilson, Robert. "Social choice theory without the Pareto principle." Journal of Economic Theory 5.3 (1972): 478-486. • "keeps the assumption that every social ranking is possible" That is not an assumption in this question though. – Giskard Dec 11 '17 at 14:03	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8690738081932068, "perplexity": 1004.5243806784739}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579251678287.60/warc/CC-MAIN-20200125161753-20200125190753-00448.warc.gz"}
https://learn.saylor.org/course/view.php?id=93&sectionid=963	• ### Unit 9: Basic Select Statements The Select statement or command is used to find and extract data from specified tables and which satisfy specified conditions. Completing this unit should take you approximately 3 hours.	{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8540321588516235, "perplexity": 5521.882942991993}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-34/segments/1596439735833.83/warc/CC-MAIN-20200803195435-20200803225435-00424.warc.gz"}
http://math.stackexchange.com/questions/248821/notations-in-group-theory	# Notations in Group theory I will start by apologizing as many will not like this question. I am reading the paper COHOMOLOGY THEORY OF GROUPS WITH A SINGLE DEFINING RELATION and having focused on typology throughout my studies i finding myself to be in a lost notation wise. 1. Let $F$ be a free subgroup in $G$ with generators $x_i$ , then elements in $F$ are represented by "words" or a final sequence of $x_i^{\pm1}$. In Page 650 (first one in this article) and 658 they state that every such word $R$ "can be expressed uniquely as a power $R=Q^q$ for $q$ maximal" Nowhere do they explain what is this $Q$, any ideas, links, resources for me to search in? 2. Let $R$ be a normal subgroup in $G$, what does the notation $(R, R)$ symbolize? they used it in pages 650 and 658 without ever explaining. Am i reading this paper wrong? Or are these notation so common they are never introduced? - 1. $R=xyz$ can be written as $R=(xyz)^1$, so here $Q=xyz$. $R=xyxy$ can be written as $R=(xy)^2$, so here $Q=xy$. 2. Is probably the commutator. – user641 Dec 1 '12 at 21:38 Oh, that makes sense, thank you very much, What about (R,R)? – user44874 Dec 1 '12 at 21:42 The general references for one-relator groups are two books, both called "combinatorial group theory" (the second was named in honour of the first!). The first was by Magnus, Karrass and Solitar, the second by Lyndon (he who wrote the paper you are reading) and Schupp. I suppose they're pretty out of date now, but they are excellent places to start: the tools laid down by Magnus in his 1931 thesis are still used today! – user1729 Dec 3 '12 at 10:24 1. Maybe you prefer more elaborate would be a formulation like this: "For every word $R$ over the alphabet $A$ there exist $(Q,q)$ such that $Q$ is a word over the alphabet $A$ and $q\in\mathbb N$ and $R=Q^q$ is the $q$-fold concatenation of $Q$ with itself. One example of such a pair for arbitray $R$ is $(R,1)$ as trivially $R=R^1$. If $R$ is not the empty word, then $Q$ in such a pair cannot be the empty word and hence $q$ is bounded from above by the length of the word $R$. Hence there exist such pairs $(Q,q)$ for which $q$ attains te maximal possible value. Since $Q_1\ne Q_2$ implies $Q_1^q\ne Q_2^q$ (if $q\ge 1$), the word $Q$ for which the maximal possible $q$ is attained, is uniquely determined." 2. Since they refer in passing to $R/(R,R)$ as the abelianized group, $(R,R)$ should denote the commutator. Today, writing $[R,R]$ seems to be the preferred notation.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9209490418434143, "perplexity": 361.83587168396656}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207928102.74/warc/CC-MAIN-20150521113208-00066-ip-10-180-206-219.ec2.internal.warc.gz"}
https://www.physicsforums.com/threads/su-2-pure-ym-on-r-4.585649/	# SU(2) Pure YM on R^4 1. Mar 10, 2012 ### Charles_Henry 1. The problem statement, all variables and given/known data Derive the pure SU(2) YM theory on $\mathbb{R}^4$ from the action. Let $A_{\mu} (x)$ be a solution to these equations. Show: $\tilde{A}_{\mu} (cx)$ is also a solution (with the same action). Background The Euclidean YM action $\mathbb{S} = - \int_{\mathbb{R^4}} Tr (F \wedge \ast F)$ yields $D \ast F = 0$ Let $\ast: \wedge^{p} \rightarrow \wedge^{D+1-p}$ be a linear map, such that $\ast (dx^{\mu_{1}} \wedge ... \wedge dx^{\mu_{p}} = \frac{\sqrt{\|det(n)!\|}}{(D+1-p)!} \epsilon^{\mu_{1}...\mu_{p}}_{{\mu}_{p+1}...{\mu}_{D+1}} dx^{\mu}_{p+1} \wedge ... \wedge dx^{{\mu}_{p+1}}$ if $G = SU(2)$ we choose a basis $T_{a}, a = 1, 2, 3$ for an Anti-Hermitian 2 x 2 matrix $T_{a}, T_{b}$ = $- \epsilon_{abc} T_{c}, T_{a} = \frac{1}{2} i \sigma_{a}$ where $Tr(T_{a}, T_{b}) = - \frac {1}{2} \delta_{ab}$ where $\sigma_{a}$ are pauli matrices, and a general group element $g = exp (\alpha^{a} T_{a} )$ with $\alpha^a$ real. Whence, $(D_{\mu} \phi)^{a} = \partial_{\mu} \phi^{a} - \epsilon^{abc} A^{b}_{\mu} \phi^{c}$ and $F^{a}_{{\mu} v} = \partial_{\mu} A^{a}_{v} - \partial_{v}A^{a}_{\mu} - \epsilon^{abc}A^{b}_{\mu}A^{c}_{v}$ when $D+1=4$ is a gauge theory in Minkowski space $M$, and $A$ is the gauge potential, $( \ast F)_{{\mu}v} = \frac{1}{2} \epsilon_{{\mu}v{\alpha}{\beta}}F^{{\alpha}{\beta}}$ A two form $F= \frac{1}{2} F_{{\mu}v}dx^{\mu} \wedge dx^{v}$ is self dual or ASD when $\ast F = F$ and $\ast F = - F$ respectively $-Tr ( F \wedge \ast F) = - \frac{1}{2} Tr (F_{{\mu}v}F^{{\mu}v}) d^{4}x = \frac{1}{4}F^{a}_{{\mu}v}F^{{\mu}va} d^{a}x$ $d^{4}x = \frac{1}{24} \epsilon_{{\mu}v{\alpha}{\beta}}dx^{\mu} \wedge dx^{v} \wedge dx^{\alpha} \wedge dx^{\beta}$ with identities $\epsilon_{{\mu}v{\alpha}{\beta}}dx^{4} = - dx^{4} \wedge dx^{v} \wedge dx^{\alpha} \wedge dx^{\beta}$ and $\epsilon_{{\alpha}{\beta}{\rho}{\sigma}} \epsilon^{{\mu}{v}{\rho}{\sigma}} = - 4 (\delta^{\mu}_{\alpha} \delta^{v}_{\beta})$ Instantons are non-singular solutions of classical equations of motion in Euclidean space whose Action is finite. $F_{{\mu}v} (x)$ ~ $O (\frac{1}{r^3})$ $A_{\mu}$ ~ $\partial_{\mu} gg^{-1} + O \frac{1}{r^2}$ as $r \rightarrow \infty$ note: I understand that the gauge transformations g(x) needs to be defined only asymptotically, so $g: \mathbb{S}^{3}_{\infty} \rightarrow SU(2)$ is extended to $\mathbb{R}^4$ if its degree vanishes: For example: If $M_{1}$ and $M_{2}$ are oriented, compact, D-dimensional manifolds without boundary, and $w$ is a volume-form on $M_{2}$. where $deg (f)$ of a smooth map $f: M_{1} \rightarrow M_{2}$ is given by $\int_{M_{1}} f\ast w = [ deg(f) ] \int_{M_{2}} w$ let $y \in M_{2}$ when $f^{-1}(y) = {x; f(x) = y}$ is finite, and the Jacobian $J(f)$ is not zero (if $x \in U$ with local coordinates $x^{i}$ and $y \in f(u)$ with local co-ordinates $y^{i}$, then we can assume: $\mathbb{J} = det \frac{\partial y^{i}}{\partial x^{J}}$ if $y^{i} (x^{1}, ... x^{D})$ deg (f) is an integer given by $deg (f) = \Sigma_{x \in f^{-1} (y)} sign [ \mathbb{J} (x) ]$ (proof withheld) therefore: $f: X \rightarrow SU(2) = S^{3}$ where X is closed. $deg(f) = \frac{1}{24\pi^2} \int_{X} Tr[(f^{-1} df)^3]$ the boundary conditions are understood in terms of one-point compactifications $S^4 = \mathbb{R}^4 \cup {\infty}$ which has a conformally equivalent metric to that of a flat metric in $\mathbb{R}^4$ A solution of YM equations on $S^4$ project stereographically to a connection on $\mathbb{R}^4$ with a curvature which vanishes at infinity. Scaling Argument: A Field(s) $(A, \phi)$ given by a potential one-form and a scalar higgs-field: $E = \int_{\mathbb{R}} d^{D}x [\|F\|^{2} + \|D \phi \|^{2} + U(\phi)$ $= E_{F} + E_{D_{\phi}} + E_{U}$ if $A(x)$ and $\phi (x)$ are critical points: $\phi_{c} (x) = \phi (cx)$ $A_{c} (x) = cA(cx)$ $F_{c} = C^{2} F(cx)$ $D_{c} \phi_{c} = c D\phi (cx)$ $E_{(c)} = \frac{1}{C^{D-4}}E_{F} + \frac{1}{C^{D+2}}E_{D_{\phi}} + \frac{1}{C^{D}}E_{U}$ $(D-4) E_{F} + (D-2) E_{D_{\phi}} + DE_{U} = 0$ note: I believe I am looking for a solution where $E_{D_{\phi}} = E_{U} = 0$ in D=4 3. The attempt at a solution A YM action S within a given topological sector $c_{2} = \frac{1}{8 \pi^2} \int_{\mathbb{R}} Tr( F \wedge F) > 0$ bounded from below by $8\pi^2c_{2}$ $F \wedge F = \ast F \wedge \ast F$ $\mathbb{S} = - \frac{1}{2} \int_{\mathbb{R}^4} Tr[(F + \ast F) \wedge (F + \ast F)] + \int_{\mathbb{R}^4} Tr (F \wedge F) = - \frac{1}{2} \int_{\mathbb{R}^4} Tr [(F + \ast F) \wedge \ast (F + \ast F) + 8 \pi^2c_{2} \geq 8 \pi^2c_{2}$ when $F = - \ast F$ hold some bib: Atiyah, M.F and Ward, R.S (1977) Instantons and Algebraic Geometry, Commun. Math. Phy. 55, 117-124 Sacks, L. and uhlenbeck, K (1981) The existence of minimal immersions of 2-spheres, Ann. Math 113, 1-24 Last edited: Mar 10, 2012 2. Mar 12, 2012 ### Charles_Henry nonsense Last edited: Mar 12, 2012 3. Mar 12, 2012 ### Charles_Henry more nonsense. Last edited: Mar 12, 2012 4. Mar 12, 2012 ### Charles_Henry ok, i see it now...derive the euler-lagrange equations from the action that leads to gauge potential. Assume we could derive a solution of pure YM IN R^4 from the Vector Potential by defining invariance along any coordinate of our choosing. Last edited: Mar 12, 2012 5. Mar 12, 2012 ### fzero This is meant to be much simpler than you're making it out to be. Literally use the Euler-Lagrange equations to obtain the equation of motion for the gauge potential. This is meant to follow from the scale-invariance of pure YM. Assume $A_{\mu} (x)$ is a solution. Consider $A_{\mu} (cx)$ and make a change of coordinates, taking into account that $A_\mu$ scales like a tensor of the appropriate degree.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9714658856391907, "perplexity": 785.225905329546}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257647475.66/warc/CC-MAIN-20180320130952-20180320150952-00317.warc.gz"}
https://www.snapxam.com/problems/40272580/integral-of-x-3-16-1x-2-0-5-dx	Step-by-step Solution Go! 1 2 3 4 5 6 7 8 9 0 a b c d f g m n u v w x y z . (◻) + - × ◻/◻ / ÷ 2 e π ln log log lim d/dx Dx \|◻\| = > < >= <= sin cos tan cot sec csc asin acos atan acot asec acsc sinh cosh tanh coth sech csch asinh acosh atanh acoth asech acsch Step-by-step explanation Problem to solve: $\int\frac{x^3}{\sqrt{16-x^2}}dx$ Learn how to solve integrals of rational functions problems step by step online. $x=4\sin\left(\theta \right)$ Learn how to solve integrals of rational functions problems step by step online. Integral of (x^3)/((16-x^2)^0.5) with respect to x. We can solve the integral \int\frac{x^3}{\sqrt{16-x^2}}dx by applying integration method of trigonometric substitution using the substitution. Now, in order to rewrite d\theta in terms of dx, we need to find the derivative of x. We need to calculate dx, we can do that by deriving the equation above. Substituting in the original integral, we get. Factor by the greatest common divisor 16. $-16\sqrt{16-x^2}+\frac{1}{3}\sqrt{\left(16-x^2\right)^{3}}+C_0$ Problem Analysis $\int\frac{x^3}{\sqrt{16-x^2}}dx$ Main topic: Integrals of Rational Functions ~ 0.21 seconds	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9920560121536255, "perplexity": 635.7226806445492}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-29/segments/1593655897168.4/warc/CC-MAIN-20200714145953-20200714175953-00039.warc.gz"}
http://math.stackexchange.com/questions/870240/an-inequality-in-numbers	# An inequality in numbers Which number is larger? $\underbrace{888\cdots8}_\text{19 digits}\times\underbrace{333\cdots3}_\text{68 digits}$ or $\underbrace{444\cdots4}_\text{19 digits}\times\underbrace{666\cdots67}_\text{68 digits}$? Why? How much is it larger? - Let those four numbers be $a,b,c,d$ respectively. Then $a=2c$ and $d=2b+1$. So $cd-ab=c$. - note that $$\underbrace{888\cdots8}_\text{19 digits}=2\underbrace{444\cdots4}_\text{19 digits}$$ and $$2\underbrace{333\cdots3}_\text{68 digits}=\underbrace{666\cdots6}_\text{68 digits}$$ further $$\underbrace{666\cdots6}_\text{68 digits}+1=\underbrace{666\cdots7}_\text{68 digits}$$ Thus $$\underbrace{888\cdots8}_\text{19 digits}\underbrace{333\cdots3}_\text{68 digits}=\underbrace{444\cdots4}_\text{19 digits}2\underbrace{333\cdots3}_\text{68 digits}= \underbrace{444\cdots4}_\text{19 digits}\underbrace{666\cdots6}_\text{68 digits}$$ which is by $\underbrace{444\cdots4}_\text{19 digits}$ smaller than $$\underbrace{444\cdots4}_\text{19 digits}\underbrace{666\cdots7}_\text{68 digits}=\underbrace{444\cdots4}_\text{19 digits}\underbrace{666\cdots6}_\text{68 digits}+\underbrace{444\cdots4}_\text{19 digits}$$ - $\underbrace{888\cdots8}_\text{19 digits}\not=2\times\underbrace{444\cdots4}_\text{19 digits}$. Why did you write it???/ – bigli Jul 17 '14 at 20:46 it most truly does. $42=8$, $442=88$, $444*2=888$ etc. – cirpis Jul 17 '14 at 20:48 Excuse me. You are right. – bigli Jul 17 '14 at 20:52 No problem, looking at my solution i can tell that i shouldve represented those big numbers using letters for a more elegant and less confusing proof. – cirpis Jul 17 '14 at 20:53 In your answer: How did you get the last equality? – bigli Jul 17 '14 at 20:55 You have $\underbrace{888\cdots8}_\text{19 digits}\times\underbrace{333\cdots3}_\text{68 digits} = 8\cdot 3 \cdot (\underbrace{111\cdots1}_\text{19 digits}\times \underbrace{111\cdots1}_\text{68 digits}) = 24 \cdot (\underbrace{111\cdots1}_\text{19 digits}\times \underbrace{111\cdots1}_\text{68 digits})$. Similarly we get $\underbrace{444\cdots4}_\text{19 digits}\times\underbrace{666\cdots6}_\text{68 digits} = 4\cdot 6 \cdot (\underbrace{111\cdots1}_\text{19 digits}\times \underbrace{111\cdots1}_\text{68 digits}) = 24 \cdot (\underbrace{111\cdots1}_\text{19 digits}\times \underbrace{111\cdots1}_\text{68 digits})$. So these two numbers are equal. It is clear that $$\underbrace{444\cdots4}_\text{19 digits}\times\underbrace{666\cdots6}_\text{68 digits} \le \underbrace{444\cdots4}_\text{19 digits}\times\underbrace{666\cdots7}_\text{68 digits}.$$ Since the multiplier is increased by one, the difference is exactly $\underbrace{444\cdots4}_\text{19 digits}$. -	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9307522177696228, "perplexity": 1311.301352242655}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-18/segments/1429246662032.70/warc/CC-MAIN-20150417045742-00035-ip-10-235-10-82.ec2.internal.warc.gz"}
http://mathhelpforum.com/number-theory/146755-polynomtials-multiple-roots-print.html	# Polynomtials with multiple roots Show 40 post(s) from this thread on one page Page 1 of 2 12 Last • May 28th 2010, 08:46 AM 1337h4x Polynomtials with multiple roots Hello All, My book states the following: [PART ONE] If 'b' is any integer and the polynomial f(x)=(x^2)+bx+1 factors (poly mod 9), there exists 3 distinct non-negative integers 'q' less than than 9 so that f(q) = 0(mod 9). How can this be proven? [PART TWO] If 'b' is any integer and the polynomial f(x)=(x^2)+bx+1 factors (poly mod 8), then f(x) is a square. E.g. f(x) = ((x+c)^2)(poly mod 8) where 0<c<8. Can anyone think of values of b that makes this possible? • May 29th 2010, 07:21 PM roninpro Is there something preventing you from doing either part by force? Just put in every single value of $b$ and see what happens. • May 29th 2010, 07:23 PM 1337h4x Quote: Originally Posted by roninpro Is there something preventing you from doing either part by force? Just put in every single value of $b$ and see what happens. I don't know what you mean. I have tried a couple different approaches but haven't gotten anywhere. That's why I'm asking for help and some guidance. • May 29th 2010, 07:30 PM roninpro For example, in part one, try $b=0$. Then, we have the polynomial $f(x)=x^2+1$. It does not factor, so we move on. Again, try $b=1$. It does not factor, so move on. Continue this until you reach $b=8$. If your polynomial factors for some $b$, check that it does have three roots. • May 29th 2010, 07:32 PM 1337h4x Quote: Originally Posted by roninpro For example, in part one, try $b=0$. Then, we have the polynomial $f(x)=x^2+1$. It does not factor, so we move on. Again, try $b=1$. It does not factor, so move on. Continue this until you reach $b=8$. If your polynomial factors for some $b$, check that it does have three roots. Sorry, I'm not following how that will help me with either my 1st or 2nd question. Could someone be more direct ? • May 29th 2010, 07:34 PM roninpro What part of my explanation are you not following? • May 29th 2010, 07:39 PM 1337h4x Quote: Originally Posted by roninpro What part of my explanation are you not following? Well what values can you get for the second one to prove it? I can't find any... • May 29th 2010, 07:45 PM roninpro The question asks you to show that for all $b$, if the polynomial $x^2+bx+1$ factors, then it has a certain number of roots. Since we are working modulo 8 or 9, we can just check every single value of $b$ and see if the result is true. (There are only finitely many values.) Are you having a problem with factoring or finding roots of polynomials? • May 29th 2010, 07:46 PM 1337h4x Quote: Originally Posted by roninpro The question asks you to show that for all $b$, if the polynomial $x^2+bx+1$ factors, then it has a certain number of roots. Since we are working modulo 8 or 9, we can just check every single value of $b$ and see if the result is true. (There are only finitely many values.) Are you having a problem with factoring or finding roots of polynomials? I brute force it for the FIRST question and all i get is for b=2 i get (x+1)(x+1), but that's it. I still don't understand the SECOND question at all. • May 30th 2010, 12:59 PM chiph588@ It's safe to assume $b\in\{0,1,2,3,4,5,6,7,8\}$ since we're working modulo $9$. roninpro says to just plug each possible value of $b$ into $f(x)$ and see what you get. • May 30th 2010, 01:26 PM 1337h4x Quote: Originally Posted by chiph588@ It's safe to assume $b\in\{0,1,2,3,4,5,6,7,8\}$ since we're working modulo $9$. roninpro says to just plug each possible value of $b$ into $f(x)$ and see what you get. I did but the only one that factored was when b=2 which factored into (x+1)^2 but I don't see how that will help me considering that I know only 1 distinct root. Is this even right or am I doing something wrong? What other ones exist? • May 30th 2010, 01:36 PM chiph588@ I'll do one for you. Take $b=7$: $f(x)=x^2+7x+1\equiv x^2-2x+1 \bmod{9}$ So $f(x)\equiv(x-1)^2\bmod{9}$ Now solve $(x-1)^2\equiv0\bmod{9}$ We see $x=\{1,4,7\}$ are roots. • May 30th 2010, 01:56 PM 1337h4x Quote: Originally Posted by chiph588@ I'll do one for you. Take $b=7$: $f(x)=x^2+7x+1\equiv x^2-2x+1 \bmod{9}$ So $f(x)\equiv(x-1)^2\bmod{9}$ Now solve $(x-1)^2\equiv0\bmod{9}$ We see $x=\{1,4,7\}$ are roots. So are 1,4,7 the 3 distinct roots? How did you get them? I just need to see one of those conversions like what you did for b = 7. How did you change that over to a mod 9? • May 30th 2010, 02:01 PM chiph588@ Quote: Originally Posted by 1337h4x So are 1,4,7 the 3 distinct roots? How did you get them? I just need to see one of those conversions like what you did for b = 7. How did you change that over to a mod 9? what? • May 30th 2010, 02:37 PM chiph588@ Since you don't get what we're saying, let me try a different approach. We're given $x^2+bx+1$ factors modulo $9$ i.e. $x^2+bx+1\equiv (x-a)(x-c)\bmod{9}$ But $(x-a)(x-c)=x^2-(a+c)x+ac\equiv x^2+bx+1\bmod{9}$ So $ac\equiv1\bmod{9}\implies c\equiv a^{-1}\bmod{9}$ We then get $x^2+bx+1\equiv x^2-(a+a^{-1})x+1\bmod{9}$ for some $a$ that has an inverse modulo $9$. Here's all $a$ with an inverse: $\begin{tabular}{c \| c}\hline a & a inverse\\\hline 1 & 1 \\ 2 & 5 \\ 4 & 7 \\ 5 & 2 \\ 7 & 4 \\ 8 & 8 \\\hline \end{tabular}$ Looking at the table we see there are four cases to consider: $a=1$: $f(x)\equiv x^2-(1+1)x+1\equiv(x-1)^2 \bmod{9}$ $a=2$: $f(x)\equiv x^2-(2+5)x+1\equiv(x+1)^2 \bmod{9}$ $a=4$: $f(x)\equiv x^2-(4+7)x+1\equiv(x-1)^2 \bmod{9}$ $a=8$: $f(x)\equiv x^2-(8+8)x+1\equiv(x+1)^2 \bmod{9}$ Thus if $x^2+bx+1$ factors modulo $9$ then $f(x)\equiv (x\pm1)^2\bmod{9}$. Now check to see there are three roots for both cases (this should be very easy). Show 40 post(s) from this thread on one page Page 1 of 2 12 Last	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 57, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7986047863960266, "perplexity": 565.7817757106177}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-23/segments/1406510261771.50/warc/CC-MAIN-20140728011741-00153-ip-10-146-231-18.ec2.internal.warc.gz"}
https://sbseminar.wordpress.com/2008/08/10/theta-divisors-the-clean-part/	Theta divisors: the clean part As often happens, after I do a large computation, a lot more theory makes sense. So, in this post, I’ll talk about the parts that I can explain without getting dirty with formulae. After that, I’ll think there willl be one more post on $\Theta$ functions and divisors. Suppose we have an abelian variety $A$ of dimension $g$ and we have a cohomology class $\beta$ in $H^2(A, \mathbb{Z})$. Suppose that $\beta$ is the Chern class of a line bundle. We will be interested in the question of to what extent we can canonically choose a line bundle with Chern class $\beta$. (Later, we will ask the same questions regarding whether there is a hypersurface with class Poincare dual to $\beta$.) The application to our original question is when $A$ is the Jacobian of a Riemann surface $X$ and $\beta$ is the class of the $\Theta$ disivor in $Pic^{g-1}(X)$. (The ambiguity in identifying $Pic^0(X)$ with $Pic^{g-1}(X)$ is topologically trivial.) By the way, when is $\beta$ could be the Chern class of a line bundle? If and only if it is a Hodge class. This is the main case in which the Hodge conjecture has been proved. This is a fascinating subject, but I’ll be ignoring it. We have a map $Pic(A) \to H^2(A, \mathbb{Z})$ which maps a holomorphic line bundle to its first Chern class. The kernel of this map is called $Pic^0(A)$ and the image is called the Neron-Severi group, $NS(A)$. So we have a short exact sequence: $0 \to Pic^0(A) \to Pic(A) \to NS(A) \to 0. \ ()$ The question we are asking is whether we can find a natural way of splitting this sequence. Let ${[-1]}$ be the endomorphism of $A$ which sends every point to its inverse. Then ${[-1]}$ acts on all three terms of $()$. The interesting thing is that ${[-1]}$ acts by negation on the left term and acts trivially on the right. If we were dealing with a short exact sequence of real vector spaces, or more generally of $\mathbb{Z}[1/2]$ modules, this would let us split the sequence immediately. We would simply split $Pic(A)$ into its $(-1)$ eigenspace, which would be $Pic^0(A)$, and its $1$ eigenspace, which would be $NS(A)$. We can still try to mimic this, but life will be trickier because we can’t divide by ${2}$. Choose an arbitrary lift $\gamma$ of $\beta$ to $Pic(A)$. Then $\gamma + [-1]^* \gamma$ is independent of the choice of $\gamma$. There are $2^{2g}$ bundles $L$ such that $2 L = \gamma + [-1]^* \gamma$, each of which has class $\beta$. So, there isn’t one canonical choice of $L$, but we can get down to a discrete $2^{2g}$ choices, as opposed to the entire continuum of choices that we would naively see. Now, this post has been about line bundles. What happens with divisors? If a line bundle $L$ has Chern class $\beta$, then $\beta$ is the class (Poincare dual to) the zero locus of any section of $L$. In general, $L$ will have many sections. Precisely, assuming that $L$ is ample, $\beta$ induces a skew symmetric form on $H_1(A, \mathbb{Z})$, and the dimension of $H^0(L)$ is the Pfaffian of that form. In particular, as will be the case in our intended application to $\Theta$-functions, if $\beta$ induces a perfect pairing on $H_1(A, \mathbb{Z})$, then $L$ has a unique nonzero section (up to scaling). So, in that case, we can use the methods above to find a canonical divisor $D$, modulo translation by ${2}$-torsion, whose cohomology class is $\beta$. What is this divisor explicitly? It is determined by the condition that ${[-1]}D=D$. (Note that translating $D$ by a ${2}$-torsion point preserves the truth of this condition.) It’s a good exercise to trace through the previous definitions and see that this works. Now, all of this was in the context of a general abelian variety with a specified Hodge class that gives an ample line bundle and induces a perfect pairing on $H^1(A, \mathbb{Z})$. (The terminology for this is a principally polarized abelian variety.) In the particular case of the Jacobian, it is a nice exercise (using Riemman-Roch) to check that, if $\kappa$ is any point of $Pic^{g-1}(X)$ with $2 \kappa =K$ then $\Theta - \kappa = - (\Theta - \kappa)$. Thus, the previously described construction does yield the translate of the $\Theta$ divisor by some square root of the canonical bundle. (As several commenters told me.) That is the end of what can be done nicely, and without reference to explicit $\Theta$ functions (or indeed, any analysis). What $\Theta$ functions let you do, given a choice of basis for $H_1(A,\mathbb{Z})$, is to make a choice of one of the $2^{2g}$ possible line bundles on $A$. More on this in the forthcoming (and final post) “Theta functions: the funky part”! 4 thoughts on “Theta divisors: the clean part” 1. Nice! That clears up some issues I hadn’t been understanding… I haven’t really worked out the details, but shouldn’t most of this story (all except paragraph -4) go through even if the variety is not principally polarized? The Prym isn’t principally polarized… Can you say something about the picture in the non-principally-polarized case? (although this has nothing to do with your original question). 2. Yeah, I think that the only importance of principal polarization is that it gives you a unique section of the line bundle. In the general case, everything works the same way on the level of line bundles. We can then ask, if we are given an isomorphism ${[-1]}^* L \cong L$, how does ${[-1]}$ act on $H^0(L)$? To find a divisor $D$ of class $\beta$, we’d want to find a section in $H^0(L)$ which is an eigenvalue for ${[-1]}$. That divisor will vanish to an even order at the identity (possibly zero) if it comes from a ${1}$-eigenvector and to odd order if it comes from a ${(-1)}$-eignevector. In the principally polarized case, $H^0(L)$ is one dimensional and the zero locus of its section is called an even or odd $\Theta$ divisor according to which of these cases holds. The above seems to depend on our choice of isomorphism ${[-1]}^* L \cong L$ but we can remove the dependency. Any two such isomorphisms differ by a nonvanishing holomorphic function on $A$, which must be a constant. We can normalize that constant by requiring our isomorphism to act trivially on the fiber over the identity. So don’t worry about that. As you’ll see in the next post, we can write down a basis for $H^0(L)$ using $\Theta$ functions and that basis is an eigenbasis for $H^0(L)$. So it would be easy to work out how many ${1}$ and how many ${-1}$ eigenvalues occur. But I haven’t found a nice way to formulate the result. 3. Small typo: “When is beta could be…” I’ve been trying to learn this stuff myself, so I’ll reread this when I’m less jet-lagged and sleepy! Thanks for writing it.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 91, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9477786421775818, "perplexity": 139.858440804134}, "config": {"markdown_headings": false, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-50/segments/1480698541864.44/warc/CC-MAIN-20161202170901-00358-ip-10-31-129-80.ec2.internal.warc.gz"}
http://opencm3.net/doc/help/gen_html/libm3/src/pickle/ver2/Pickle2.i3.html	## libm3/src/pickle/ver2/Pickle2.i3 Distributed only by permission. modified on Tue Dec 8 11:32:52 1992 by gnelson A {\it pickle} is a representation of a Modula-3 value as a stream of bytes. Writing a value as a pickle and then reading it back produces a value equivalent'' to the original value, in the sense that the value's non-ref fields have the same contents and that their REF and OBJECT fields are = in the same places. In other words, pickles preserve value, shape and sharing. You can write pickles for values that have cyclic references (such as doubly-linked lists), or that are arbitrary graph structures. Pickles are used both to communicate values between two programs running at the same time and to store a value and reuse it in a program running later. Pickles preserve ordinal values (integers and enumerations) exactly, automatically performing any byte-swapping that may be required. An exception is raised if a pickled ordinal value is too large to be represented in a program reading the pickle. Pickles preserve floating point values as well as possible considering that the two machines may have different floating point representations. Pickles do not preserve untraced references. Any untraced references will turn into NIL if they are pickled, regardless of their value. Pickles preserve the names and signatures of procedures, but the code for the procedures can be different in the program writing the pickle and the program reading the pickle. Object methods are treated the same as procedures. Sharing is preserved within pickles, but not between pickles. Pickles are written and read by a single-pass algorithm that uses modest auxiliary tables and does not require a seekable stream. For example, if you compile and run the following program: MODULE P1 EXPORTS Main; IMPORT Pickle, IO; TYPE T = REF RECORD val: INTEGER END; BEGIN Pickle.Write(IO.OpenWrite("A.pickle"), NEW(T, val := 6)) END P1. and then in the same directory, you compile and run the following program: MODULE P2 EXPORTS Main; IMPORT Pickle, IO; TYPE U = REF RECORD val: INTEGER END; BEGIN IO.Put(Fmt.Int(v.val) & "\n") END P2. then P2 will read the pickle written by P1 and will print 6. Notice that the type of the pickled reference was named differently in P1 and P2; but this doesn't present any problem, since Modula-3 uses structural equivalence. If you pickle a BRANDED REF INTEGER, there is no guarantee that you will be able to read it back as a BRANDED REF INTEGER, since the implicit brand can vary from program to program. Therefore, you should use explicit brands in types that will be pickled. SRC/PM3/EXM3 Incompatibility notes: 1. Pickles written by programs compiled by SRC, PM3, or EZM3 are not generally readable by CM3-compiled programs because of byte-order differences in the writing of fingerprints in pickles. These differences are probably also endian-dependent. 2. In CM3, for a type recorded in a pickle to be readable, the type must be declared in the EXPORT/IMPORT closure of the main program. This is more restrictive than in SRC/PM3/EZM3, where it is enough that the type be declared in an interface or module named in the m3makefile. Thus, porting code that uses pickles from PM3 to CM3 could require adding new IMPORTs. INTERFACE Pickle2; EXCEPTION Error(TEXT); PROCEDURE Write(wr: Wr.T; ref: REFANY) Trace the data structure reachable via traced references from ref, convert it into a pickle, and write the pickle to wr, starting at the current position of wr and leaving wr positioned after the last byte written. Read a pickle from rd, reconstruct a copy of the pickled data structure, and return it. The bytes to be read start at rd's current position; rd is left positioned after the last byte consumed. Most people should go no further. The remainder of the interface allows you to customize the pickling and unpickling of selected types. There are two ways of doing this: you can override the methods of objects called {\it pickle writers} and {\it pickle readers}, or you can register {\it specials} for particular types. Several examples are presented after the end of the interface. \paragraph{Pickle writers and readers.} A Pickle.Writer is an object whose write method writes pickles to the writer stored in its wr data field. You can override the write method to produce special effects. TYPE TypeCode = INTEGER; Used to represent types of allocated objects. A TypeCode value is valid within a single execution of a single program. There are methods in Writer and Reader objects for writing and reading program-independent representations of a TypeCode. TYPE Writer <: WriterPublic; WriterPublic = OBJECT wr: Wr.T; METHODS write(r: REFANY) RAISES writeType(tc: TypeCode) RAISES writeInt(i: INTEGER) RAISES END; If w is a Pickle.Writer, then w.write(r) traces the data structure reachable via traced references from r, converts it into a pickle, and writes the pickle to w.wr, starting at the current position of w.wr and leaving w.wr positioned after the last byte written. The default method w.write(r) behaves as follows: \begin{itemize} \item If r=NIL, write a representation of NIL on w.wr. \item Otherwise if r has been previously written to the current pickle, write the index of r in this pickle on w.wr. \item Otherwise, find the Special (as defined below) for the closest supertype of r's allocated type for which a special has been registered. Let sp be this special (note that there always is such a special, since the implementation registers a special for REFANY). Call writeType(sp.sc), then write a representation of TYPECODE(r), then invoke sp.write(r, w). \end{itemize} The call w.writeType(tc) writes bytes on w.wr to represent the type tc in a program-independent fashion. These bytes are a fingerprint: fingerprints have the property that if two Modula-3 types are equivalent, then their fingerprints are equal; and with extremely hight probability, if their fingerprints are equal then they are equivalent. Note that the implementation of this method optimizes so that if a type is written to a pickle many times, occurences after the first typically occupy only one byte. The call w.writeInt(i) writes bytes on w.wr to represent the integer i in a platform-independent fashion. In particular, the readInt method of a subsequent Pickle.Reader can read the integer correctly, even if executed on a platform with different byte order or integer size (if possible). A Pickle.Writer may be serially re-used to pickle multiple objects. The call Pickle.Write(wr, ref) is equivalent to (but more efficient than) the following: NEW(Pickle.Writer, wr := wr).write(ref) A Pickle.Reader is an object whose read method reads pickles from the reader stored in its rd data field. You can override the read method to produce special effects. TYPE RefID = INTEGER; rd: Rd.T; METHODS noteRef(ref: REFANY; id: RefID); END; If r is a Pickle.Reader, then r.read() reads a pickle from r.rd, reconstructs a copy of the pickled data structure, and returns it. The bytes to be read start at r.rd's current position; r.rd is left positioned after the last byte consumed. The default method r.read(r) behaves as follows: \begin{itemize} \item If r.rd contains a representation of NIL, consume those bytes and return NIL. \item Otherwise, if r.rd contains the index of a previously read value in this pickle, consume those bytes and return that value. \item Otherwise compute sc = readType(), and proceed as follows. Find the registered special sp (as defined below) whose sp.sc field equals sc. Read the representation of a type code ac from r.rd. Let id be the index that the result of this method will have in the pickle. Invoke sp.read(ac, r, id), call r.noteRef(result, id), and return the result. Note that in the default case sp will be RootSpecial(), defined below. \end{itemize} In order to implement the second case above, the Pickle.Reader maintains a table mapping indexes to references. In simple cases this table can be maintained entirely by the r.read method, which places the result of the sp.read invocation into the table. But if the value being unpickled will contain an occurence of its own reference (the second case above), the reference must be placed in the table before unpickling that occurence. To do so, the special's read method must call r.noteRef before any such occurrence. More exactly, a special's read method must call r.noteRef before any occurrence of the ref that the read method will return, giving noteRef the reference and the refID that was a parameter of the read method. If there is no such occurrence, the special need not (but may) call r.noteRef. It is a checked runtime error to call r.noteRef with a value other than the value that will be returned by the special's read method; it is OK to call r.noteRef multiple times with the same value. The call r.readType reads bytes from r.rd that represent a type, as written by the writeType method of a Writer, and converts them into a typecode valid in the current execution of the current program. If there is no such type, or if the bytes couldn't correspond to ones written by the writeType method, raises Pickle.Error. The call r.readInt reads bytes from r.rd that represent an integer, as written by a writer's writeInt method, and converts them into an integer, taking into consideration reperesentation differences such as byte order and integer length. It raises Pickle.Error if the integer cannot be represented on this machine. A Pickle.Reader may be serially re-used to unpickle multiple objects. The call Read(rd) is equivalent to (but more efficient than) the following: RETURN NEW(Reader, rd := rd).read(); \paragraph{Specials.} Specials provide for customized pickling of specified data types on every call of read or write in this process. A client can achieve this effect for individual calls of read or write by using a sub-class of Pickle.Reader or Pickle.Writer, and checking for that sub-class (using TYPECASE) inside the special. The implementation of this interface registers a special for the type REFANY; this is special is the value of a call NEW(Special), i.e. its methods are the default methods of the type Special. There are three constraints on the methods of a special: \begin{itemize} \item the methods must leave the Rd.T or Wr.T positioned after the last byte read or written; \item the read method must consume the number of bytes written by the write method; \item the read method must produce a value equivalent to the one that was given to the write method. \end{itemize} If these rules are violated, the result could be either a checked runtime error or an invalid result from reading a pickle. There are many ways to program a special. For example, the write method could modify the value and then call the root special. Or the write method could create a related value and call writer.write or Special.write. Or it could write some data fields individually and call writer.write for selected sub-values of its value. Or it could use mixtures of these techniques. TYPE SpecialPublic = OBJECT prev: SpecialPublic := NIL; sc: TypeCode; METHODS write(ref: REFANY; writer: Writer) RAISES {Error, Rd.EndOfFile, Rd.Failure, END; Special <: SpecialPublic; The special's write method should write a representation of ref's contents on wr, in a manner analogous to the default Special.write method. The value ref is not NIL and its allocated type is a sub-type of sc. The default write method calls writer.writeType(TYPECODE(ref)), then writes on writer.wr the bytes of ref's untraced data fields, then calls writer.write(x) for each traced value x directly contained in ref. The special's read method must return an appropriate value read from rd. If the value might involve a reference to itself, the special must pass the value and id to r.noteRef before the first such occurrence of the value. In other situations the special need not (but may) call r.noteRef. See the earlier discussion of the r.read method. The result of the read method must be a value acceptable in the context where the method is being invoked. For example, if the method is being invoked to read the contents of a field of a record, the result must be assignable to the declared type of the field. It is always correct to return a value of the same type as the value that was written when the pickle was created, but a sub-type might be acceptable too. The default read method reads a typecode tc by calling reader.readType(), allocates a value whose type-code is tc, passes the allocated value to the reader's noteRef method, reads the bytes of its untraced data fields from reader.rd, then for each directly contained traced reference calls reader.read() and assigns the result into the appropriate field of the allocated value; finally it returns the value. Note that the special's methods can use the writeType and readType methods of the Writer or Reader to record relevant type information. For example they could record the allocated type of the value being pickled in the same way as the default methods do, or they could record more extensive type information if available, such as the entire type ancestry of the value's type. PROCEDURE RegisterSpecial(sp: Special); Register sp as the special for pickling and unpickling objects having type code sp.sc. After you call RegisterSpecial(sp), the special sp will be called from a Pickle.Writer's write method, or a Pickle.Reader's read method, to pickle or unpickle objects whose type is sp.sc, or whose type is a sub-type of sp.sc and has no closer registered special. It is a checked runtime error to register a special sp when there is already a special registered with the same sp.sc. There is always a special registered for REFANY that special's methods are the default methods of the type Special. PROCEDURE ReRegisterSpecial(sp: Special); ReRegister sp as the special for pickling and unpickling objects having type code sp.sc. Registering means that, unlike with RegisterSpecial, a special can already exist for sp. It will be saved in sp.prev and can be called by the read and write methods of sp. END Pickle2. \paragraph{Examples.} For example, suppose you are writing a pickle that contains many references of type TEXT, and you want to modify the pickling process so that any texts that are Text.Equal will share storage. (By default, texts in the pickle will share storage if and only if they shared storage in the original data structure.) Of course this modification will mean that the unpickled value will have more sharing than the original value. A simple way to achieve this is to build the following subtype of Pickle.Writer: TYPE WriterP = Pickle.Writer OBJECT tbl: TxtTxtTbl.T METHODS init(): WriterP := InitP OVERRIDES write := WriteP END; PROCEDURE WriteP(self: WriterP; r: REFANY) VAR txt: TEXT; BEGIN IF ISTYPE(r, TEXT) THEN IF self.tbl.get(r, txt) THEN r := txt ELSE EVAL self.tbl.put(r, r) END END; Pickle.Writer.write(self, r) END WriteP; PROCEDURE InitP(self: WriterP): WriterP = BEGIN self.tbl := NEW(TxtTxtTbl.T).init() RETURN self END InitP; The WriterP object keeps a table with an entry for every text that has been encountered in the pickle. When the method WriteP encounters a reference r of type TEXT, it checks if the table contains a text txt that is Text.Equal to r. (A TxtTxtTbl.T considers two texts to be the same key if they are Text.Equal.) If so, txt is pickled instead of r; if not, r is entered into the table so that if any text is later encountered that is Text.Equal to r, then r will be pickled in its place. In either case, the subtype method WriteP delegates the actual work of writing the bytes into the pickle to its supertype method Pickle.Writer.write. Given the program above, you can pickle a data structure ref to the writer wr, identifying texts that have the same contents, with: NEW(WriterP, wr := wr).init()(ref) For this example, no special processing is necessary when reading; you just use an ordinary Pickle.Reader, or a normal call to Pickle.Read. Next we consider a simple example of the use of specials. Suppose that you have a type defined by TYPE T = REF RECORD ref: REFANY; tc: CARDINAL END in which the tc field represents a Modula-3 typecode. Since typecodes are address-space specific, it is necessary to translate the tc field so that it represents the same Modula-3 type in the address space reading the pickle as it did in the address space that wrote the pickle. This is achieved by using the procedures RTTypeFP.ToFingerPrint and RTTypeFP.FromFingerprint, which translate between typecodes and type fingerprints. A type fingerprint is a 64-bit hash value that with high probability identifies a Modula-3 type in an address-space independent way. A fingerprint is represented as an ARRAY [0..7] OF [0..255]. Here is one way to register specials for type T: TYPE TSpecial = Pickle.Special OBJECT OVERRIDES write := WriteT; END; PROCEDURE WriteT( self: TSpecial; ref: REFANY; wr: Pickle.Writer) VAR t: T := ref; fp := RTTypeFP.ToFingerPrint(t.tc); BEGIN FOR i := 0 TO 7 DO Wr.PutChar(wr.wr, VAL(fp[i], CHAR)) END; wr.write(t.ref) END WriteT; PROCEDURE ReadT( ac: INTEGER; id: RefID): REFANY RAISES {Error, Rd.EndOfFile, Rd.Failure, VAR fp: ARRAY [0..7] OF [0..255]; res: T; BEGIN FOR i := 0 TO 7 DO fp[i] := ORD(Rd.GetChar(rd.rd)) END; res := NEW(t, tc := RTTypeFP.FromFingerprint(fp)); rd.noteRef(res, id); RETURN res ... Pickle.RegisterSpecial( NEW(TSpecial, tc := TYPECODE(T))) It is important to understand the call to rd.noteRef made by the special's read method. The effect of the call is to make an entry in the pickle reader's table recording that res is the reference associated with id. This is essential because the recursive call to rd.read might encounter additional instances of id, if some value t of type T is reachable from its own t.ref field. As a final example, suppose that T is an object instead of a REF RECORD: TYPE T = OBJECT ref: REFANY; tc: CARDINAL END. The solution above still works for objects whose allocated type is T, but it doesn't work for objects whose allocated type is a subtype of T that has additional fields. Here are new methods for the special that automatically handle subtypes (assuming that any additional fields do not themselves require non-standard translation): PROCEDURE WriteT( self: TSpecial; ref: REFANY; wr: Pickle.Writer) VAR t: T := ref; fp := RTTypeFP.ToFingerPrint(t.tc); BEGIN FOR i := 0 TO 7 DO Wr.PutChar(wr.wr, VAL(fp[i], CHAR)) END; Special.write(t, wr) END WriteT; PROCEDURE ReadT( ac: INTEGER; id: RefID): REFANY RAISES {Error, Rd.EndOfFile, Rd.Failure, VAR fp: ARRAY [0..7] OF [0..255]; res: T; BEGIN FOR i := 0 TO 7 DO fp[i] := ORD(Rd.GetChar(rd.rd)) END; res.tc := RTTypeFP.FromFingerprint(fp); RETURN res In this case the special uses the root special to transmit the whole object in the usual way. The write special also sends the fingerprint, which the read special uses to fix up the typecode. Notice that with this strategy, the call to rd.noteRef is not required.	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.22892868518829346, "perplexity": 3834.0565828085173}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-09/segments/1550247481992.39/warc/CC-MAIN-20190217111746-20190217133746-00463.warc.gz"}
https://zims-en.kiwix.campusafrica.gos.orange.com/wikipedia_en_all_nopic/A/Euler%E2%80%93Rodrigues_formula	# Euler–Rodrigues formula In mathematics and mechanics, the EulerRodrigues formula describes the rotation of a vector in three dimensions. It is based on Rodrigues' rotation formula, but uses a different parametrization. The rotation is described by four Euler parameters due to Leonhard Euler. The Rodrigues formula (named after Olinde Rodrigues), a method of calculating the position of a rotated point, is used in some software applications, such as flight simulators and computer games. ## Definition A rotation about the origin is represented by four real numbers, a, b, c, d such that ${\displaystyle a^{2}+b^{2}+c^{2}+d^{2}=1.}$ When the rotation is applied, a point at position x rotates to its new position ${\displaystyle {\vec {x}}'={\begin{pmatrix}a^{2}+b^{2}-c^{2}-d^{2}&2(bc-ad)&2(bd+ac)\\2(bc+ad)&a^{2}+c^{2}-b^{2}-d^{2}&2(cd-ab)\\2(bd-ac)&2(cd+ab)&a^{2}+d^{2}-b^{2}-c^{2}\end{pmatrix}}{\vec {x}}.}$ ### Vector formulation The parameter a may be called the scalar parameter, while ω = (b, c, d) the vector parameter. In standard vector notation, the Rodrigues rotation formula takes the compact form ${\displaystyle {\vec {x}}'={\vec {x}}+2a({\vec {\omega }}\times {\vec {x}})+2\left({\vec {\omega }}\times ({\vec {\omega }}\times {\vec {x}})\right)}$ ### Symmetry The parameters (a, b, c, d) and (−a, −b, −c, −d) describe the same rotation. Apart from this symmetry, every set of four parameters describes a unique rotation in three-dimensional space. ### Composition of rotations The composition of two rotations is itself a rotation. Let (a1, b1, c1, d1) and (a2, b2, c2, d2) be the Euler parameters of two rotations. The parameters for the compound rotation (rotation 2 after rotation 1) are as follows: {\displaystyle {\begin{aligned}a&=a_{1}a_{2}-b_{1}b_{2}-c_{1}c_{2}-d_{1}d_{2};\\b&=a_{1}b_{2}+b_{1}a_{2}-c_{1}d_{2}+d_{1}c_{2};\\c&=a_{1}c_{2}+c_{1}a_{2}-d_{1}b_{2}+b_{1}d_{2};\\d&=a_{1}d_{2}+d_{1}a_{2}-b_{1}c_{2}+c_{1}b_{2}.\end{aligned}}} It is straightforward, though tedious, to check that a2 + b2 + c2 + d2 = 1. (This is essentially Euler's four-square identity, also used by Rodrigues.) ## Rotation angle and rotation axis Any central rotation in three dimensions is uniquely determined by its axis of rotation (represented by a unit vector k = (kx, ky, kz)) and the rotation angle φ. The Euler parameters for this rotation are calculated as follows: {\displaystyle {\begin{aligned}a&=\cos {\frac {\varphi }{2}};\\b&=k_{x}\sin {\frac {\varphi }{2}};\\c&=k_{y}\sin {\frac {\varphi }{2}};\\d&=k_{z}\sin {\frac {\varphi }{2}}.\end{aligned}}} Note that if φ is increased by a full rotation of 360 degrees, the arguments of sine and cosine only increase by 180 degrees. The resulting parameters are the opposite of the original values, (−a, −b, −c, −d); they represent the same rotation. In particular, the identity transformation (null rotation, φ = 0) corresponds to parameter values (a, b, c, d) = (±1, 0, 0, 0). Rotations of 180 degrees about any axis result in a = 0. ## Connection with quaternions The Euler parameters can be viewed as the coefficients of a quaternion; the scalar parameter a is the real part, the vector parameters b, c, d are the imaginary parts. Thus we have the quaternion ${\displaystyle q=a+bi+cj+dk,}$ which is a quaternion of unit length (or versor) since ${\displaystyle \left\\|q\right\\|^{2}=a^{2}+b^{2}+c^{2}+d^{2}=1.}$ Most importantly, the above equations for composition of rotations are precisely the equations for multiplication of quaternions. In other words, the group of unit quaternions with multiplication, modulo the negative sign, is isomorphic to the group of rotations with composition. ## Connection with SU(2) spin matrices The Lie group SU(2) can be used to represent three-dimensional rotations in 2 × 2 matrices. The SU(2)-matrix corresponding to a rotation, in terms of its Euler parameters, is ${\displaystyle U={\begin{pmatrix}\ \ \,a+di&b+ci\\-b+ci&a-di\end{pmatrix}}.}$ Alternatively, this can be written as the sum {\displaystyle {\begin{aligned}U&=a\ {\begin{pmatrix}1&0\\0&1\end{pmatrix}}+b\ {\begin{pmatrix}0&1\\-1&0\end{pmatrix}}+c\ {\begin{pmatrix}0&i\\i&0\end{pmatrix}}+d\ {\begin{pmatrix}i&0\\0&-i\end{pmatrix}}\\&=a\,I+ic\,\sigma _{x}+ib\,\sigma _{y}+id\,\sigma _{z},\end{aligned}}} where the σi are the Pauli spin matrices. Thus, the Euler parameters are the coefficients for the representation of a three-dimensional rotation in SU(2).	{"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 9, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9039814472198486, "perplexity": 782.892373110474}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623488556482.89/warc/CC-MAIN-20210624171713-20210624201713-00463.warc.gz"}

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