bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source
Authors: Pikin A. , Beebe E. N. , Raparia D.
Published: March 2013

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions’ charge states, and therefore, the ions’ energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.
Thermal activation at moderate-to-high and high damping: Finite barrier effects and force spectroscopy
Authors: Mazo J. J. , Fajardo O. Y. , Zueco D.
Published: March 2013

We study the thermal escape problem in the moderate-to-high and high damping regime of a system with a parabolic barrier. We present a formula that matches our numerical results accounting for finite barrier effects, and compare it with previous works. We also show results for the full damping range. We quantitatively study some aspects on the relation between mean first passage time and the definition of an escape rate. To finish, we apply our results and considerations in the framework of force spectroscopy problems. We study the differences on the predictions using the different theories and discuss the role of \documentclass[12pt]{minimal}\begin{document}$\gamma \dot{F}$\end{document}γḞ as the relevant parameter at high damping.
Study of the $\tilde{\rm X}^2\Pi$X̃2Π state of the SiCN/SiNC Renner-Teller system
Authors: Brites Vincent , Mitrushchenkov Alexander O. , Léonard Céline
Published: March 2013

The potential energy surfaces of both components of the \documentclass[12pt]{minimal}\begin{document}$\tilde{\rm X}^2\Pi$\end{document}X̃2Π electronic ground state of the double Renner-Teller SiCN/SiNC system are calculated using explicitly correlated coupled cluster approach. The SiNC minimum is found to lie at 628 cm−1 above the SiCN one. The isomerization transition state is found at 7583 cm−1 on the 2A′ surface and at 7936 cm−1 on the 2A″ surface. The cyclic local minimum on surface 2A′ is also reproduced by our potential energy surface and is located at 3901 cm−1. The calculated potentials are used to simulate rovibrational spectroscopy employing the recently developed EVEREST variational code. It is shown that Renner-Teller interaction (ε = 0.3043 for SiCN and ε = 0.3874 for SiNC) and spin-orbit coupling are both very important for a correct description of the spectroscopy of this system. Comparison with available experimental measurement is reported.
New estimators of spectral distributions of Wigner matrices
Authors: Zhou Wang
Published: March 2013

We introduce kernel estimators for the semi-circular law. In this first part of our general theory on the estimators, we prove the consistency and conduct simulation study to show the performance of the estimators. We also point out that Wigner's semi-circular law for our new estimators and the classical empirical spectral distributions is still true when the elements of Wigner matrices do not have finite variances but are in the domain of attraction of normal law.
Photo-induced electric phenomena in antiferromagnetic BiFeO3 ceramics
Authors: Hung C.-M. , Jiang M.-D. , Anthoninappen J. , Tu C.-S.
Published: March 2013

Photovoltage and photocurrent density have been measured in BiFeO3 multiferroic ceramic (with electrodes of indium tin oxide and Au films) before and after a dc E-field poling sequence. The photovoltaic responses under near-ultraviolet illumination (λ = 405 nm) exhibit nonlinear dependence on light intensity. The relation between photovoltaic responses and light intensity can be described using the exponential equations VOC = Vb[1−exp(−I/α)] and JSC = Jb[1 − exp(−I/β)], where VOC, JSC, Vb, and Jb are the open-circuit photovoltage, short-circuit photocurrent density, balanced photovoltage, and balanced photocurrent density, respectively. The maximal power conversion efficiency is about 0.002% at illumination intensity of 2.3 W/m2. The photovoltaic responses can be enhanced after a dc E-field poling.
Equilibrium molecular dynamics simulations for the thermal conductivity of Si/Ge nanocomposites
Authors: Li Xiaobo , Yang Ronggui
Published: March 2013

Various methods have been used to study the thermal conductivity of nanocomposites which are playing increasing roles in energy conversion and thermal management. However, when the size of particle inclusions is on the order of several nanometers, the existing macro- and meso-scale analytical methods cannot be used to predict the thermal conductivity of nanocomposites due to the existence of both phonon wave interference and particle scattering effects. In this study, equilibrium molecular dynamics (EMD) is explored to study the thermal conductivity of Si/Ge nanocomposites. We found that EMD can be used to study the thermal conductivity of nanocomposites when multiple nanoparticles are included to avoid the artificial effect of simulation domain sizes. We then calculated the thermal conductivity of Si/Ge nanocomposites with different volumetric ratio and particle size at 300 K. The result shows that the thermal conductivity of Si/Ge nanocomposites first decreases and then increases with decreasing particle size at fixed volumetric ratio. The decreasing thermal conductivity is due to the increased phonon scattering at high surface to volumetric ratio. When the particle size is further reduced, the thermal conductivity recovers due to the phonon wave interference effect. The effect of particle shape on the thermal conductivity of Si/Ge nanocomposites is also studied.
Interplay between chemical state, electric properties, and ferromagnetism in Fe-doped ZnO films
Authors: Chen G. , Peng J. J. , Song C. , Zeng F. , Pan F.
Published: March 2013

Valence state of Fe ions plays an important role in the physical properties of Fe doped ZnO films. Here, a series of Zn1−xFexO films with different Fe concentrations (x = 0, 2.3, 5.4, 7.1, and 9.3 at. %) were prepared to investigate their structural, piezoelectric, ferroelectric, bipolar resistive switching properties, and electrical-control of ferromagnetism at room temperature. The structure characterizations indicate that the chemical state of Fe ions substituting Zn2+ site changes from Fe3+ to Fe2+ with the increase of Fe dopant concentration. We found enhanced piezoelectric and ferroelectric properties in Zn0.977Fe0.023O films with more Fe3+ due to the smaller Fe3+ ionic size in comparison with Zn2+ while the increase of Fe2+ concentration by a larger amount of Fe dopant results in the worse ferroelectric and piezoelectric performance. All Pt/Zn1−xFexO/Pt devices show bipolar resistive switching properties. Especially, devices with lower Fe dopant concentration exhibit better endurance properties due to their higher crystalline quality. The variation of oxygen vacancies during resistive switching provides an opportunity to tune ferromagnetism of Fe-doped ZnO films, giving rise to the integration of charge and spin into a simple Pt/Zn1−xFexO/Pt devices. The multifunctional properties of Fe-doped ZnO films are promising for communication systems and information storage devices.
Device performance and bias instability of Ta doped InZnO thin film transistor as a function of process pressure
Authors: Park Hyun-Woo , Kim Boo-Kyoung , Park Jin-Seong , Chung Kwun-Bum
Published: March 2013

The device performance and bias instability of radio frequency (RF) sputtered Ta doped InZnO thin film transistors (TFTs) were investigated as a function of deposition process pressure. Under low process pressure, the electrical characteristics of TaInZnO TFTs were enhanced with amorphous physical structure and the decrease of oxygen deficient bonding states. These changes were correlated with the evolution of electronic structure, such as band alignment and band edge states below the conduction band. As the process pressure decreased, the energy difference between conduction band minimum and Fermi level and the band edge states was decreased. In particular, the relative energy level of band edge states was moved into the deep level within bandgap, with the increase of process pressure.
Trapped fields greater than 7 T in a 12 mm square stack of commercial high-temperature superconducting tape
Authors: Patel A. , Filar K. , Nizhankovskii V. I. , Hopkins S. C. , Glowacki B. A.
Published: March 2013

Superconducting bulks can be magnetized to act as powerful permanent magnets; however, for high trapped fields at temperatures below 77 K, bulks have poor thermal stability and are limited by low mechanical strength. The trapped fields reported in this paper are between two stacks of commercial high-temperature superconducting tape each with 120 layers, magnetized by field cooling. 7.34 T was trapped at approximately 4.2 K, the highest field ever achieved for such a sample. The trapped field also continued to increase below 20 K showing high thermal stability, largely due to the silver over-layer which effectively dissipates heat.
Stress pulse attenuation in shear thickening fluid
Authors: Jiang Weifeng , Gong Xinglong , Xuan Shouhu , Jiang Wanquan , Ye Fang , Li Xiaofeng , Liu Taixiang
Published: March 2013

The stress pulse attenuation of the 62 vol/vol. % dense silica particle-ethylene glycol suspension was investigated by using a modified spilt Hopkinson pressure bar. In comparison to the neat ethylene glycol solution, the transmission pulse of the shear thickening is much weaker under the same impact condition. No energy loss is progressed for the neat ethylene glycol solution, thus it can be concluded that the energy dissipation behavior was happened in the silica particle based shear thickening fluid. In this work, the energy dissipation of the shear thickening fluid was reversible.
Carbon mineralisation and pore size classes in undisturbed soil cores
Authors: Bouckaert Liesbeth , Sleutel Steven , Van Loo Denis , Brabant Loes , Cnudde Veerle , Van Hoorebeke Luc , De Neve Stefaan
Published: March 2013

Soil pore network effects on organic matter turnover have, until now, been studied indirectly because of lack of data on the 3D structure of the pore network. Application of X-ray computed tomography (X-ray CT) to quantify the distribution of pore neck size and related pore sizes from undisturbed soil cores, with simultaneous assessment of carbon (C) mineralisation, could establish a relationship between soil organic matter (SOM) decomposition and soil pore volumes. Eighteen miniature soil cores (diameter 1.2 cm, height 1.2 cm) covering a range of bulk densities were incubated at 20°C for 35 days. Respiration was modelled with a parallel first- and zero-order kinetic model. The cores were scanned at 9.44 µm resolution using an X-ray CT scanner developed in-house. Correlation analysis between the slow pool C mineralisation rate, ks, and pore volume per pore neck class yielded significant (P < 0.05) positive correlations: r = 0.572, 0.598, and 0.516 for the 150–250, 250–350, and >350 µm pore neck classes, respectively. Because larger pores are most probably mainly air-filled, a positive relation with ks was ascribed to enhanced aeration of smaller pores surrounding large pores. The weak and insignificant relationship between the smallest pore neck class (<9.44 µm) and ks could be explained by obstructed microbial activity and mobility or diffusion of exo-enzymes and hydrolysis products as a result of limited oxygen availability. This study supports the hypothesis that the impact of soil structure on microbial processes occurs primarily via its determination of soil water distribution, which is possibly the main driver for the location of C mineralisation in the soil matrix.
Urban space, political identity and the unwanted legacies of state socialism: Bucharest's problematic Centru Civic in the post-socialist era
Authors: Light Duncan , Young Craig
Published: March 2013

This paper explores the relationship between the urban cultural landscape of Bucharest and the making of post-socialist Romanian national identity. As the capital of socialist Romania, central Bucharest was extensively remodelled by Nicolae Ceauşescu into the Centru Civic in order to materialize Romania's socialist identity. After the Romanian “Revolution” of 1989, the national and local state had to deal with a significant “leftover” socialist urban landscape which was highly discordant with the orientation of post-socialist Romania and its search for a new identity. Ceauşescu's vast socialist showpiece left a difficult legacy which challenges the material and representational reshaping of Bucharest and constructions of post-socialist Romanian national identity more broadly. The paper analyzes four attempts to deal with the Centru Civic: developments in the immediate post-1989 period; the international architectural competition Bucureşti 2000; proposals for building a Cathedral of National Salvation; and the Esplanada project. Despite over 20 years of proposals central Bucharest remains largely unchanged. The paper thus deals with a failed attempt to re-shape the built environment in support of national goals.
The Southern Square in the Baltic Pearl: Chinese ambition and “European” architecture in St. Petersburg, Russia
Authors: Dixon Megan L.
Published: March 2013

The Baltic Pearl is a 205-hectare development project underway southwest of St. Petersburg, Russia, originally financed and designed by a consortium of firms from Shanghai, China. This paper analyzes the discourse surrounding the development of one section of the Baltic Pearl, the commercial multiplex Southern Square, particularly the use of the term “European” as used to signal the project's intended cultural orientation and to exert control over the interaction between Russian planners and Chinese developers. In the negotiation over the form of the multiplex, control over architectural style emerges as leverage for preservation of cultural norms and local autonomy. In further analysis, the situation emerges as an example of Sassen's [(2008)Territory, Authority, Rights. From Medieval to Global Assemblages.Princeton: Princeton University Press] shifting assemblages, that is, a reassembling of global influences in a space invoked as national as well as local.
K and Ba distribution in the structures of the clathrate compounds KxBa16−x(Ga,Sn)136(x= 0.8, 4.4, and 12.9) and KxBa8−x(Ga,Sn)46(x= 0.3)
Authors: Schäfer Marion C. , Bobev Svilen
Published: March 2013

Studies of the K–Ba–Ga–Sn system produced the clathrate compounds K0.8(2)Ba15.2(2)Ga31.0(5)Sn105.0(5)[a= 17.0178 (4) Å], K4.3(3)Ba11.7(3)Ga27.4(4)Sn108.6(4)[a= 17.0709 (6) Å] and K12.9(2)Ba3.1(2)Ga19.5(4)Sn116.5(4)[a= 17.1946 (8) Å], with the type-II structure (cubic, space groupFd\overline{3}m), and K7.7(1)Ba0.3(1)Ga8.3(4)Sn37.7(4)[a= 11.9447 (4) Å], with the type-I structure (cubic, space groupPm\overline{3}n). For the type-II structures, only the smaller (Ga,Sn)24pentagonal dodecahedral cages are filled, while the (Ga,Sn)28hexakaidecahedral cages remain empty. The unit-cell volume is directly correlated with the K:Ba ratio, since an increasing amount of monovalent K occupying the cages causes a decreasing substitution of the smaller Ga in the framework. All three formulae have an electron count that is in good agreement with the Zintl–Klemm rules. For the type-I compound, all framework sites are occupied by a mixture of Ga and Sn atoms, with Ga showing a preference for Wyckoff site 6c. The (Ga,Sn)20pentagonal dodecahedral cages are occupied by statistically disordered K and Ba atoms, while the (Ga,Sn)24tetrakaidecahedral cages encapsulate only K atoms. Large anisotropic displacement parameters for K in the latter cages suggest an off-centering of the guest atoms.
A dinuclear zinc complex containing a diamond-core geometry: [Zn2(μ2-GueO)2(GueO)2(py)2]·0.5(toluene) (GueOH is guethol)
Authors: Petrus Rafał , Sobota Piotr
Published: March 2013

The title zinc alkoxide, bis(μ-2-ethoxyphenolato)-κ3O1,O2:O1;κ3O1:O1,O2-bis[(2-ethoxyphenolato-κ2O1,O2)(pyridine-κN)zinc(II)] toluene hemisolvate, [Zn2(C8H9O2)4(C5H5N)2]·0.5C7H8, crystallizes with two independent complex molecules located on inversion centres and one independent toluene solvent molecule disordered about an inversion centre. The ZnIIatoms are six-coordinated in distorted octahedral geometries with O5N donor sets. The ZnIIions and bridging alkoxide groups are arranged in a diamond Zn2O2core structure. The guetholate (2-ethoxyphenolate) ligands adopt two different coordination modes,viz.peripheral chelating and μ2-bridging. Preliminary investigations of the catalytic activity of the compound in the ring-opening polymerization of L-lactide demonstrate rapid and efficient generation of polylactide.
Angular spectrum simulation of X-ray focusing by Fresnel zone plates
Authors: Vila-Comamala Joan , Wojcik Michael , Diaz Ana , Guizar-Sicairos Manuel , Kewish Cameron M. , Wang Steve , David Christian
Published: March 2013

A computing simulation routine to model any type of circularly symmetric diffractive X-ray element has been implemented. The wavefield transmitted beyond the diffractive structures is numerically computed by the angular spectrum propagation method to an arbitrary propagation distance. Cylindrical symmetry is exploited to reduce the computation and memory requirements while preserving the accuracy of the numerical calculation through a quasi-discrete Hankel transform algorithm, an approach described by Guizar-Sicairos & Gutierrez-Vega [J. Opt. Soc. Am. A, (2004),21, 53–58]. In particular, the code has been used to investigate the requirements for the stacking of two high-resolution Fresnel zone plates with an outermost zone width of 20 nm.
Matter in Place
Authors: Laviolette Patrick , Labrum Bronwyn
Published: March 2013

Editorial
Book reviews
Authors: MacRae Graeme
Published: March 2013

ABORTION THEN AND NOW: NEW ZEALAND ABORTION STORIES FROM 1940–1980 By Margaret SparrowWellington: Victoria University Press, 2010. 304pp. RRP $50ISBN 978 0 864736 32 1Reviewed by Sarah Donovan
Thumbing Through The Physics Teacher
Authors: Iona Steve
Published: March 2013

The formation of The Physics Teacher (TPT) journal was proposed in 1961, and the first issue was published in April 1963. I was in fifth grade. Little did I know that TPT would touch my life many times during the next 50 years. Let me share some observations from the first issue of each decade, beginning in 1963 and continuing until 2013.
Thinking Outside of the Rectangular Box
Authors: Kagan Mikhail
Published: March 2013

As we typically teach in an introductory mechanics course, choosing a “good” coordinate frame with convenient axes may present a major simplification to a problem. Additionally, knowing some conserved quantities provides an extremely powerful problem-solving tool. While the former idea is typically discussed in the context of Newton's laws, the latter starts with introducing conservation of energy even later. This work presents an elegant example of implementing both aforementioned ideas in the kinematical context, thus providing a “warm-up” introduction to the standard tools used later on in dynamics. Both the choice of the (non-orthogonal) coordinate frame and the conserved quantities are rather nonstandard, yet at the same time quite intuitive to the problem at hand. Two such problems are discussed in detail with two alternative approaches. The first approach does not even require knowledge of calculus. In an online appendix,1 I also present the brute-force solution involving a coupled system of differential equations. In addition, a few exercises and another similar problem for students' “homework” are provided in the appendix.
Revisiting the Least Force Required to Keep a Block from Sliding
Authors: De Subhranil
Published: March 2013

This article pertains to a problem on static friction that concerns a block of mass M resting on a rough inclined plane. The coefficient of static friction is μs and the inclination angle θ is greater than tan−1 μs. This means that some force F must be applied (see Fig. 1)1 to keep the block from sliding down the incline. Familiar textbook versions of this problem ask for the minimum value of F when it is applied in a certain specified direction, for example, parallel to the incline (φ= 0 in Fig. 1) or perpendicular to the incline (φ= 90°). Here, we generalize the problem by allowing the direction of the force to be adjustable and asking what the absolute minimum value of F is in order to keep the block from sliding.
Reproducing Eratosthenes' Determination of Earth's Circumference on a Smaller Scale
Authors: Takemae Seiji , Kirwin Peter , McIntosh Gordon
Published: March 2013

In this paper, we describe a lab activity for measuring a spherical balloon's circumference. The procedure we discuss is based on the method used by Eratosthenes to measure the Earth's circumference.
Augmented Reality Comes to Physics
Authors: Buesing Mark , Cook Michael
Published: March 2013

Augmented reality (AR) is a technology used on computing devices where processor-generated graphics are rendered over real objects to enhance the sensory experience in real time. In other words, what you are really seeing is augmented by the computer.1 Many AR games already exist for systems such as Kinect and Nintendo 3DS and mobile apps, such as Tagwhat and Star Chart (a must for astronomy class). The yellow line marking first downs in a televised football game2 and the enhanced puck that makes televised hockey easier to follow3 both use augmented reality to do the job.
Late-Quaternary Climatic Trends and History of Lake Erie from Stable Isotope Studies
Authors: Fritz P. , Anderson T. W. , Lewis C. F. M.
Published: March 2013

Oxygen and carbon isotope measurements on mollusk and carbonate shells separated from a long sediment core in central Lake Erie document climatic changes of the Great Lakes region and the evolution of Lake Erie since deglaciation. On the basis of
18
O data, two major climatic improvements are recognized, one occurring between 13,000 and 12,000 years before the present (B.P.) and the other between 10,000 and 8,000 years B.P. Changing drainage patterns are also reflected in the
18
O contents of the Lake Erie water. Carbon isotopes reflect changes in aquatic vegetation and water depth. The settlement and industrialization of the Lake Erie drainage basin is documented in the
13
C and
18
O contents of modern mollusks.
Precambrian Paleomagnetism: Magnetizations Reset by the Grenville Orogeny
Authors: McWilliams M. O. , Dunlop D. J.
Published: March 2013

Paleomagnetic results from iron-rich metasediments folded during the Grenville orogeny (∼1000 million years ago) indicate that stable remanence was acquired after folding as the rock cooled from above 615°C through 550°C. As well as imparting a new remanence, the thermal event destroyed any preexisting magnetizations. In a proposed model, virtually all Grenville paleomagnetic poles have been reset and can provide no evidence of plate tectonic processes before 1000 million years ago, The polar sequence suggested by potassium-argon age trends within the Grenville province does, however, indicate rapid drift of North America between 1000 and 900 million years ago.
Phosphine on Jupiter and Implications for the Great Red Spot
Authors: Prinn Ronald G. , Lewis John S.
Published: March 2013

A study of the chemistry and photochemistry of the recently discovered phosphine in the atmosphere of Jupiter suggests that the red colorations on this planet result from photochemical production of red phosphorus particles. Chemical-dynamical models of this red phosphorus haze imply that the intensity of the red coloration is a strong function of the strength of vertical turbulent mixing in the atmosphere. If the Jovian Great Red Spot is a region of considerable dynamical activity our model provides a self-consistent explanation for the redness of this region in comparison to the rest of the planet.
Photoacoustic Effect with Solids: A Theoretical Treatment
Authors: Rosencwaig Allan , Gersho Allen
Published: March 2013

Chopped light impinging on a solid sample in an enclosed cell produces an acoustic signal within the cell. A derivation for the acoustic pressure supports the experimental observation that optical absorption spectra may be obtained from the acoustic signal even when the sample is completely opaque to transmitted light.
Vocabulary Richness: A Sociolinguistic Analysis
Authors: Sankoff David , Lessard Réjean
Published: March 2013

A regression analysis of lexical diversity in the informal speech of 120 mature speakers of French in Montreal reveals no direct effect of socioeconomic level or residential milieu. All social effects are mediated by a single variable: educational attainment. The analysis also confirms a continuing enrichment of productive vocabulary with increasing age.
Auto-Shaping in Rats to the Presentation of Another Rat Predicting Food
Authors: Timberlake William , Grant Douglas L.
Published: March 2013

Rats direct social rather than eating behavior toward a stimulus rat that predicts the imminent delivery of food. This result suggests that a predictive stimulus does not become a substitute for a reward, but its characteristics elicit and support a particular subset of the responses commonly related to that reward.
Fuel Formation from Aqueous Ferric Bromide by Photolysis in the Visible
Authors: Chen Schoen-Nan , Lichtin Norman N. , Stein Gabriel
Published: March 2013

Illumination of acid aqueous ferric bromide containing excess bromide yields free Br
2
and ferrous ions. The quantum yield is independent of wavelength up to about 600 nanometers, and increases with temperature; quantum yields of up to about 5 percent ½Br
2
were observed at 42°C and further improvement should be possible. Some aspects of this system for the quantum utilization of solar energy are discussed.
Shanidar IV, a Neanderthal Flower Burial in Northern Iraq
Authors: Solecki Ralph S.
Published: March 2013

The discovery of pollen clusters of different kinds of flowers in the grave of one of the Neanderthals, No. IV. at Shanidar cave, Iraq. furthers our acceptance of the Neanderthals in our line of evolution. It suggests that, although the body was archaic, the spirit was modern.
Spout of the Gray Whale: Its Physical Characteristics
Authors: Kooyman G. L. , Norris K. S. , Gentry R. L.
Published: March 2013

In a calm lagoon of Baja California the spout or blow of adult and young gray whales,
Eschrichtius robustus
, was observed. Of three calves the maximum flow rate was 200 liters per second, and the duration of both expiration and inspiration was slightly less than 1 second. Gas passes through the external nares at 44 meters per second during inspiration and four to five times this rate during expiration. At this latitude the whale's spout consists mainly of seawater blown up during expiration.
Niche Analysis of a Zooplankton Community
Authors: Makarewicz Joseph C. , Likens Gene E.
Published: March 2013

The division of the niche hyperspace has been demonstrated for the limnetic zooplankton community of Mirror Lake. New Hampshire. The niche structure of the zooplankton community is conceived as an intensive or intracommunity population continuum corresponding to the niche hyperspace. The community of zooplankton is a system of interacting populations whose adaptive centers do not overlap and have evolved toward dispersion in relation to the complex gradients of food size, depth, and time.
Vespula squamosa
: A Yellow Jacket Wasp Evolving Toward Parasitism
Authors: McDonald John F. , Matthews Robert W.
Published: March 2013

Evidence from behavior and from nest architecture implicates
Vespula squamosa
as a temporary, apparently facultative social parasite of
V. maculifrons
. Analysis of 66
V. squamosa
nests collected in northern Georgia revealed that 54 were initially built by
V. maculifrons
. Three very young
V. maculifrons
nests, each with a
V. squamosa
queen and workers of both species, confirmed the parasitic propensity.
Continental Ice Sheets: Conditions for Growth
Authors: Barry Roger G. , Andrews John T. , Mahaffy Mary A.
Published: March 2013

The conditions required for the development of major ice sheets in eastern Canada appear to have been approximated by those of the Little Ice Age in the 17th through the 19th centuries. Former extensive snowbanks from this period have been mapped from lichen-free terrain visible on Earth Resources Technology Satellite imagery. The climatic changes required to initiate the necessary snow line lowering may involve only a minor summer cooling. Simulations with an ice-flow model reproduce plausible ice centers. but the rate of ice sheet buildup is slower than that suggested by geological evidence of world sea level lowering from 120,000 to 115,000 years before the present.
Fraction 1 Protein and the Origin of Polyploid Wheats
Authors: Chen K. , Gray J. C. , Wildman S. G.
Published: March 2013

The nature of the interspecific hybridizations giving rise to the polyploid wheats has been determined from an analysis of the polypeptide compositions of fraction 1 proteins isolated from diploid, tetraploid, and hexaploid wheat species. In the origins of the tetraploid wheat, the B-genome donor provided the chloroplast genome and was therefore the maternal parent in the cross with
Triticum monococcum
. Subsequently, the tetraploid wheat,
T. dicoccum
, was the maternal parent in the cross with
Aegilops squarrosa
, giving rise to the hexaploid wheat,
T. aestivum
. Of the small number of diploid species examined, only
Ae. speltoides
has a chloroplast genome similar to that of the polyploid wheats.
Onfield assessment of concussion in the adult athlete
Authors: Putukian Margot , Raftery Martin , Guskiewicz Kevin , Herring Stanley , Aubry Mark , Cantu Robert C , Molloy Mick
Published: March 2013

Background

The onfield assessment of concussion in the adult athlete is challenging, given the elusiveness of injury, the sensitivity and specificity of the sideline assessment tools and the evolving nature of concussive injury. This paper reviews the evidence related to the onfield assessment and considers questions related to same day return to play, what to do when no physician is available onsite, as well as the benefit of remote notification of potential concussive events.

Objective

To review the evidence regarding the onfield assessment of concussion in the adult athlete. Additional key issues to consider include same day return to play for the adult athlete with concussion, what to do in a community setting when no doctor is present and whether there is any benefit with remote notification of potential concussive events that occur on the playing field.

Data Sources

Systematic literature review of concussion assessment and management. PubMed, MEDLINE, Psych Info and Cochrane Library databases were reviewed using the MeSH key words concussion and mild traumatic brain injury combined with athletic injuries. Each was refined by adding the key words ‘adult’, ‘sideline assessment’, ‘onfield assessment’ and ‘return to play’.

Results

For the MEDLINE search, using ‘concussion’ and ‘athletic injuries’ as key words, there were 880 results, and refining by ‘adult’ there were 292 results. When ‘traumatic brain injury’ and ‘athletic injuries’ were combined, there were 210 results. When refining by ‘adult’, there were 89 results. Many of these results overlapped. Following an initial review, these articles form the basis of the discussion.

Conclusions

The onfield evaluation of sport-related concussion is often a challenge, given the elusiveness and variability of presentation, difficulty in making a timely diagnosis, specificity and sensitivity of the sideline assessment tools and the reliance on symptoms. Despite these challenges, the sideline evaluation is based on recognition of injury, assessment of symptoms, cognitive and cranial nerve function and balance. Serial assessments are often necessary and, since signs and symptoms may be delayed, erring on the side of caution (keeping an athlete out of participation when there is any suspicion for injury) is important. A standardised assessment of concussion is useful in the assessment of the athlete with suspected concussion but should not take the place of the clinician's judgement.
The difficult concussion patient: what is the best approach to investigation and management of persistent (>10 days) postconcussive symptoms?
Authors: Makdissi Michael , Cantu Robert C , Johnston Karen M , McCrory Paul , Meeuwisse Willem H
Published: March 2013

Background

Concussion in sport typically recovers clinically within 10 days of injury. In some cases, however, symptoms may be prolonged or complications may develop. The objectives of the current paper are to review the literature regarding the difficult concussion and to provide recommendations for an approach to the investigation and management of patients with persistent symptoms.

Methods

A qualitative review of the literature on concussion in sport was conducted with a focus on prolonged recovery, long-term complications and management including investigation and treatment strategies. MEDLINE and Sports Discus databases were reviewed.

Results

Persistent symptoms (>10 days) are generally reported in 10–15% of concussions. This figure may be higher in certain sports (eg, ice hockey) and populations (eg, children). In general, symptoms are not specific to concussion and it is important to consider and manage coexistent pathologies. Investigations may include formal neuropsychological testing and conventional neuroimaging to exclude structural pathology. Currently, there is insufficient evidence to recommend routine clinical use of advanced neuroimaging techniques or genetics markers. Preliminary studies demonstrate the potential benefit of subsymptom threshold activity as part of a comprehensive rehabilitation programme. Limited research is available on pharmacological interventions.

Conclusions

Cases of concussion in sport where clinical recovery falls outside the expected window (ie, 10 days) should be managed in a multidisciplinary manner by healthcare providers with experience in sports-related concussion. Important components of management, after the initial period of physical and cognitive rest, include associated therapies such as cognitive, vestibular, physical and psychological therapy, assessment for other causes of prolonged symptoms and consideration of a graded exercise programme at a level that does not exacerbate symptoms.
Revisiting the modifiers: how should the evaluation and management of acute concussions differ in specific groups?
Authors: Makdissi Michael , Davis Gavin , Jordan Barry , Patricios Jon , Purcell Laura , Putukian Margot
Published: March 2013

Background

One of the key difficulties while managing concussion in sport is that there are few prognostic factors to reliably predict clinical outcome. The aims of the current paper are to review the evidence for concussion modifiers and to consider how the evaluation and management of concussion may differ in specific groups.

Methods

A qualitative review of the literature on concussion was conducted with a focus on prognostic factors and specific groups including children, female athletes and elite versus non-elite players. PubMed, MEDLINE and SportsDiscus databases were reviewed.

Results

The literature demonstrates that number and severity of symptoms and previous concussions are associated with prolonged recovery and/or increased risk of complications. Brief loss of consciousness (LOC) and/or impact seizures do not reliably predict outcomes following a concussion, although a cautious approach should be adopted in an athlete with prolonged LOC or impact seizures (ie, >1 min). Children generally take longer to recover from concussions and assessment batteries have yet to be validated in the younger age group. Currently, there are insufficient data on the influence of genetics and gender on outcomes following a concussion.

Conclusions

Several modifiers are associated with prolonged recovery or increased risk of complications following a concussion and have important implications for management. Children with concussion should be managed conservatively, with an emphasis on return to learn as well as return to sport. In cases of concussions managed with limited resources (eg, non-elite players), a conservative approach should also be taken. There should be an emphasis on concussion education in all sports and at all levels, particularly in junior and community-based competitions.
Protective effect of grape seed extracts on human lymphocytes: a preliminary study
Authors: Szeto Yim Tong , Lee Kit Yee , Kalle Wouter , Pak Sok Cheon
Published: March 2013

Grape seed extracts (GSEs) possess a broad spectrum of antioxidative properties that protects various cells from free radicals and oxidative stress. In this study, the genoprotective effect of GSE on human lymphocytic DNA was studied using standard and lysed cell comet assays. Lymphocytes from 5 healthy subjects were pretreated with GSE in different concentrations. The standard and lysed cell comet assays were performed on treated, untreated, challenged, and unchallenged cells in parallel. Cells were then subjected to an oxidant challenge induced with 5-min exposures to hydrogen peroxide. In the standard comet assay, GSE significantly diminished hydrogen-peroxide-induced DNA damage in a dose-dependent manner. In the lysed cell assay, however, the antioxidant effect was diminished at a higher GSE concentration. Data indicate that the cell membrane might play a role in limiting cellular access to antioxidants, which directly affects the genoprotective or potential pro-oxidant effect of antioxidants on human DNA. Using both standard and lysed cell comet assays in parallel could be a useful way to elucidate the mechanism of protection or damage by antioxidants.
The effect of 25-hydroxyvitamin D on insulin sensitivity in obesity: is it mediated via adiponectin?
Authors: Wright Olivia R.L. , Hickman Ingrid J. , Petchey William G. , Sullivan Clair M. , Ong Cynthia , Rose Felicity J. , Ng Choaping , Prins Johannes B. , Whitehead Jonathan P. , O'Moore-Sullivan Trisha M.
Published: March 2013

There has been substantial recent interest in using vitamin D to improve insulin sensitivity and preventing/delaying diabetes in those at risk. There is little consensus on the physiological mechanisms and whether the association is direct or indirect through enhanced production of insulin-sensitising chemicals, including adiponectin. We examined cross-sectional associations between serum 25-hydroxyvitamin D (25(OH)D) and insulin sensitivity (Matsuda index), parathyroid hormone (PTH), waist circumference, body mass index (BMI), triglycerides (TG), total and high molecular weight (HMW) adiponectin, HMW : total adiponectin ratio (HMW : total adiponectin), and total cholesterol : HDL cholesterol ratio (TC:HDL cholesterol) in 137 Caucasian adults of mean age 43.3 ± 8.3 years and BMI 38.8 ± 6.9 kg/m2. Total adiponectin (standardised β = 0.446; p < 0.001), waist circumference (standardised β = –0.216; p < 0.05), BMI (standardised β = –0.212; p < 0.05), and age (standardised β = –0.298; p < 0.001) were independently associated with insulin sensitivity. Serum 25(OH)D (standardised β = 0.114; p = 0.164) was not associated with insulin sensitivity, total or HMW adiponectin, HMW : total adiponectin, or lipids. Our results provide the novel finding that 25(OH)D is not associated with HMW adiponectin or HMW : total adiponectin in nondiabetic, obese adults and support the lack of association between 25(OH)D and lipids noted by others in similar groups of patients.
ON NONEQUILIBRIUM PHYSICS AND STRING THEORY
Authors: GRAY NICKOLAS , MINIC DJORDJE , PLEIMLING MICHEL
Published: March 2013

In this paper, we review the relation between string theory and nonequilibrium physics based on our previously published work. First, we explain why a theory of quantum gravity and nonequilibrium statistical physics should be related in the first place. Then, we present the necessary background from the recent research in nonequilibrium physics. The review discusses the relationship of string theory and aging phenomena, as well as the connection between AdS/CFT correspondence and the Jarzynski identity. We also discuss the emergent symmetries in fully developed turbulence and the corresponding nonequilibrium stationary states. Finally, we outline a larger picture regarding the relationship between nonperturbative quantum gravity and nonequilibrium statistical physics. This relationship can be understood as a natural generalization of the well-known Wilsonian relation between local quantum field theory and equilibrium statistical physics of critical phenomena. According to this picture, the AdS/CFT duality is just an example of a more general connection between nonperturbative quantum gravity and nonequilibrium physics. In the appendix of this review, we discuss a new kind of complementarity between thermodynamics and statistical physics which should be important in the context of black hole complementarity.
ON CYCLE CONNECTIVITY OF GRAPHS
Authors: MATHEW SUNIL
Published: March 2013

In this article, the concept of cycle connectivity of a weighted graph is discussed. Cycle connectivity of partial trees, cycles and precisely weighted graphs are obtained. Also the concepts of cyclic cutnode and cyclic bridge in weighted graphs are introduced and a condition for a precisely weighted graph to possess a cyclic cutnode is obtained.
AN APPROXIMATE SOLUTION OF THE DYNAMICAL CASIMIR EFFECT IN A CAVITY WITH A TWO-LEVEL ATOM
Authors: FUJII KAZUYUKI , SUZUKI TATSUO
Published: March 2013

In this paper, we treat the so-called dynamical Casimir effect in a cavity with a two-level atom and give an analytic approximate solution under the general setting. The aim of the paper is to show another approach based on Mathematical Physics to the paper [Approximate analytical results on the cavity Casimir effect in the presence of a two-level atom, Phys. Rev. A85 (2012) 063804, arXiv: 1112.0523 [quant-ph]] by A. V. Dodonov and V. V. Dodonov. We believe that our method is simple and beautiful.
A NEW NOTION OF POSSIBILISTIC COVARIANCE
Authors: GEORGESCU IRINA , KINNUNEN JANI
Published: March 2013

Possibilistic indicators of fuzzy numbers (expected value, variance, and covariance) are an efficient instrument in the modeling of uncertainty phenomena. Various models of uncertainty phenomena have led to several notions of variance and covariance. In particular, the possibilistic models of risk aversion previously studied by one of the authors imposed a notion of variance of a fuzzy number different from those existing in the literature. In this paper, a new notion of covariance of two fuzzy numbers corresponding to the possibilistic variance mentioned is studied. This possibilistic covariance can be used, e.g. in models of possibilistic risk aversion with many parameters.
Bone-Marrow-Derived Mesenchymal Stem Cells for Organ Repair
Authors: Li Ming , Ikehara Susumu
Published: March 2013

Mesenchymal stem cells (MSCs) are prototypical adult stem cells with the capacity for self-renewal and differentiation with a broad tissue distribution. MSCs not only differentiate into types of cells of mesodermal lineage but also into endodermal and ectodermal lineages such as bone, fat, cartilage and cardiomyocytes, endothelial cells, lung epithelial cells, hepatocytes, neurons, and pancreatic islets. MSCs have been identified as an adherent, fibroblast-like population and can be isolated from different adult tissues, including bone marrow (BM), umbilical cord, skeletal muscle, and adipose tissue. MSCs secrete factors, including IL-6, M-CSF, IL-10, HGF, and PGE2, that promote tissue repair, stimulate proliferation and differentiation of endogenous tissue progenitors, and decrease inflammatory and immune reactions. In this paper, we focus on the role of BM-derived MSCs in organ repair.
Rodent Models for Investigating the Dysregulation of Immune Responses in Type 1 Diabetes
Authors: Chou Feng-Cheng , Chen Heng-Yi , Chen Shyi-Jou , Fang Mei-Cho , Sytwu Huey-Kang
Published: March 2013

Type 1 diabetes (T1D) is an autoimmune disease mediated by T cells that selectively destroy the insulin-producingβcells. Previous reports based on epidemiological and animal studies have demonstrated that both genetic factors and environmental parameters can either promote or attenuate the progression of autoimmunity. In recent decades, several inbred rodent strains that spontaneously develop diabetes have been applied to the investigation of the pathogenesis of T1D. Because the genetic manipulation of mice is well developed (transgenic, knockout, and conditional knockout/transgenic), most studies are performed using the nonobese diabetic (NOD) mouse model. This paper will focus on the use of genetically manipulated NOD mice to explore the pathogenesis of T1D and to develop potential therapeutic approaches.
A Comparison between Two Force-Position Controllers with Gravity Compensation Simulated on a Humanoid Arm
Authors: Muscolo Giovanni Gerardo , Hashimoto Kenji , Takanishi Atsuo , Dario Paolo
Published: March 2013

The authors propose a comparison between two force-position controllers with gravity compensation simulated on the DEXTER bioinspired robotic arm. The two controllers are both constituted by an internal proportional-derivative (PD) closed-loop for the position control. The force control of the two systems is composed of an external proportional (P) closed-loop for one system (P system) and an external proportional-integrative (PI) closed-loop for the other system (PI system). The simulation tests performed with the two systems on a planar representation of the DEXTER, an eight-DOF bioinspired arm, showed that by varying the stiffness of the environment, with a correct setting of parameters, both systems ensure the achievement of the desired force regime and with great precision the desired position. The two controllers do not have large differences in performance when interacting with a lower stiffness environment. In case of an environment with greater rigidity, the PI system is more stable. The subsequent implementation of these control systems on the DEXTER robotic bioinspired arm gives guidance on the design and control optimisation of the arms of the humanoid robot named SABIAN.
HPLC Quantification of Phenolic Acids from Vetiveria zizanioides (L.) Nash and Its Antioxidant and Antimicrobial Activity
Authors: Prajna Jha , Richa Jindal , Dipjyoti Chakraborty
Published: March 2013

Extraction procedure was standardized and for the soluble, glycoside, and wall-bound fractions of phenolic acids from Vetiveria zizanioides. The water soluble alkaline extract which represents the cell wall-bound fraction contained the highest amount of phenolic acids (2.62 ± 1.2 μM/g fwt GA equivalents). Increased phenolic content in the cell wall indicates more lignin deposition which has an important role in plant defense and stress mitigation. Antioxidant property expressed as percentage TEAC value obtained by ABTS assay was correlated with the amount of phenolic acids and showed a Pearson's coefficient 0.988 (significant at 0.01 level). The compounds p-coumaric acid, p-dihydroxybenzoic acid, and ferulic acid were detected in the acidic extracts by HPLC analysis. The plant extracts exhibited considerable antimicrobial activity against tested bacterial and fungal strains.