bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of IT‐enabled supply chain process change on job and process outcomes: A longitudinal investigation
Authors: Bala Hillol
Published: July 2013

Prior research on information technology (IT)‐enabled supply chain management (SCM) has primarily focused on macro‐level issues (e.g., IT capabilities related to SCM, and SCM design and optimization) and outcomes (e.g., firm performance). There has been limited research that focuses on micro‐level outcomes related to employees who actually execute SCM processes in organizations. These employee‐level outcomes are important because successful implementation of SCM systems and processes hinges on SCM employees’ support and commitment. I develop and test a model positing that SCM employees’ perceptions of changes in their work process characteristics, i.e., process complexity and process rigidity, following a new SCM system implementation will influence their job outcomes, i.e., job performance, job satisfaction, job anxiety, and job security, and their perceptions of process outcomes, i.e., process performance and relationship quality. The model incorporates a holistic appraisal of the extent of change—change radicalness—as a mechanism between work process characteristics and outcomes. The model is supported in three studies conducted in the context of three different SCM system implementations (N = 278, 282, and 304, respectively). In particular, I found that individuals perceived a significant change in their work process characteristics following an SCM system implementation, and changes in work process characteristics had a significant impact on job and process outcomes. These findings contribute to the information systems and operations management literatures and their intersections by offering insights on challenges related to IT‐enabled SCM innovation implementation in organizations.
“The Disorderly Conduct of a Few”: Crime and Hamilton’s Racial Geography in the Early 1850s
1
Authors: Campbell Lyndsay
Published: July 2013

Drawing on a series of criminal cases that took place in Hamilton in late 1852, this paper explores the operation of race in law during the period against the backdrop of Hamilton’s geography. The paper sheds light on the living conditions of a segment of the population that has left scarcely a trace in the historical records. As well, a close examination of Hamilton’s census records and physical space reveals that those found guilty in these trials were linked to a particular racially and ethnically charged, vice-prone space rather than the more respectable central part of the city. The author argues that the construction of Prince’s Island, which lay in the marshes just west of Hamilton, as a “den of vice” probably conditioned the findings of guilt and innocence in one of the trials while promoting the impression that justice was “colour-blind.”
Effect of rearing system (mountain pasture vs. indoor) of Simmental cows on milk composition and Montasio cheese characteristics
Authors: Romanzin Alberto , Corazzin Mirco , Piasentier Edi , Bovolenta Stefano
Published: July 2013

Dairy cattle in the Alps are traditionally maintained on high altitude pastures during summer. In recent decades, however, many farmers prefer to maintain the cows always indoor with a hay-based diet. Many authors have shown that the forage type is able to modify the characteristics of milk and cheese. Recently the product specification of PDO Montasio allowed differentiation between mountain cheeses and other products. Aim of this trial is to study the effect of rearing system on the characteristics of milk and cheese produced in this context. One hundred and twenty Simmental dairy cows were considered, 60 grazed on high altitude pasture, and 60 kept indoor and fed a hay-based diet. Cheese production was repeated in two periods (early July and late August) and ripened two and six months. Pasture-derived milk and cheese presented higher fat and lower protein content than hay-derived ones. Rearing systems also affected cheese colour. Textural parameters, hardness, gumminess and chewiness were found to be higher in pasture-derived cheese. In addition, it showed lower level of total saturated fatty acids, and higher level of mono and polyunsaturated fatty acids than hay-derived cheeses. Consumers perceived the difference of cheeses in terms of colour and holes, but they express a similar overall liking. More limited effects of period and ripening time were observed.
Large carnivores and low diversity of optimal prey: a comparison of the diets of snow leopards Panthera uncia and wolves Canis lupus in Sarychat-Ertash Reserve in Kyrgyzstan
Authors: Jumabay-Uulu Kubanychbek , Wegge Per , Mishra Charudutt , Sharma Koustubh
Published: July 2013

In the cold and arid mountains of Central Asia, where the diversity and abundance of wild ungulates are generally low, resource partitioning among coexisting carnivores is probably less distinct than in prey-rich areas. Thus, similar-sized carnivores are likely to compete for food. We compared the summer diets of snow leopards Panthera uncia and wolves Canis lupus in Sarychat-Ertash Reserve in the Tien-Shan mountains of Kyrgyzstan, based on analysis of genetically confirmed scats. Abundances of the principal prey species, argali Ovis ammon and Siberian ibex Capra sibirica, were estimated from field surveys. The diets consisted of few species, with high interspecific overlap (Pianka's index = 0.91). Argali was the predominant prey, with > 50% frequency of occurrence in both snow leopard and wolf scats. This was followed by Siberian ibex and marmots Marmota baibacina. Being largely unavailable, remains of livestock were not detected in any of the scats. In the snow leopard diet, proportions of argali and ibex were in line with the relative availabilities of these animals in the Reserve. This was in contrast to the diet of wolf, where argali occurred according to availability and ibex was significantly underrepresented. The high diet overlap indicates that the two predators might compete for food when the diversity of profitable, large prey is low. Competition may be more intense in winter, when marmots are not available. Hunting of argali and ibex outside the Reserve may be unsustainable and therefore reduce their abundances over time. This will affect both predators negatively and intensify competition for food. Reduction in ibex populations will directly affect the snow leopard, and the wolf is likely to be indirectly affected as a result of increased snow leopard predation of argali.
Xepac protein and IP3/Ca2+pathway implication duringXenopus laevisvitellogenesis
Authors: Serrano María de los Angeles , Luque Melchor Emilio , Sánchez Sara Serafina
Published: July 2013

The objective of this study was to elucidate the signalling pathways initiated by cAMP once inside theXenopus laevisoocyte, where it triggers and maintains vitellogenin endocytic uptake. Our results showed the presence ofXepactranscripts at all stages of oogenesis and we demonstrated that a cAMP analogue that exclusively activates Xepac, 8-CPT, was able to rescue the endocytic activity in oocytes with uncoupled gap junctions. Inhibition experiments for the IP3/Ca2+signalling pathway showed either a complete inhibition or a significant reduction of the vitellogenic process. These results were confirmed with the rescue capability of the A-23187 ionophore in those oocyte batches in which the IP3/Ca2+pathway was inhibited. Taking our findings into account, we propose that the cAMP molecule binds Xepac protein enabling it to activate the IP3/Ca2+pathway, which is necessary to start and maintainX. laevisvitellogenin uptake.
Ethical Challenges in Emergency Medical Services: Controversies and Recommendations
Authors: Becker Torben K. , Gausche-Hill Marianne , Aswegan Andrew L. , Baker Eileen F. , Bookman Kelly J. , Bradley Richard N. , De Lorenzo Robert A. , Schoenwetter David J.
Published: July 2013

Emergency Medical Services (EMS) providers face many ethical issues while providing prehospital care to children and adults. Although provider judgment plays a large role in the resolution of conflicts at the scene, it is important to establish protocols and policies, when possible, to address these high-risk and complex situations. This article describes some of the common situations with ethical underpinnings encountered by EMS personnel and managers including denying or delaying transport of patients with non-emergency conditions, use of lights and sirens for patient transport, determination of medical futility in the field, termination of resuscitation, restriction of EMS provider duty hours to prevent fatigue, substance abuse by EMS providers, disaster triage and difficulty in switching from individual care to mass-casualty care, and the challenges of child maltreatment recognition and reporting. A series of ethical questions are proposed, followed by a review of the literature and, when possible, recommendations for management.

BeckerTK, Gausche-HillM, AsweganAL, BakerEF, BookmanKJ, BradleyRN, De LorenzoRA, SchoenwetterDJ for the American College of Emergency Physicians’ EMS Committee. Ethical challenges in Emergency Medical Services: controversies and recommendations. Prehosp Disaster Med. 2013;28(5):1-10.
On the Equation
Authors: Crawford Lawrence
Published: July 2013

c2 = a2+b2.—If c2 = a2 + b2 and a, b, c have no common factor, then c exceeds a or b by an odd square.

No two of a, b, c must have common factor, or all three would.
New Clock Problems
Authors: Jackson J.
Published: July 2013

The following problem was suggested by a difficulty in distinguishing between the two hands of a clock.
A First Lesson in Algebra
Authors: Milne Archd
Published: July 2013

A big stumbling-block in the way of the child beginning Algebra is the transition from the conception of definite numbers in Arithmetic to that of indefinite quantities in Algebra, and the performance on these of the fundamental operations with facility and certainty. It is a truism that our algebraic teaching must grow out of our arithmetical: in its initial stages it may with advantage be based on some such method as the following. From a box of counters, or little wooden cubes, or in fact any handy articles, ask several pupils—better still, all the pupils, if the class be of convenient size—to pick out respectively five counters, eight counters, and so on. Their possessions can be exhibited on the black-board thus:—“A has five counters,” “B has eight counters,” etc. The counters being replaced, now ask others to take out some counters each. So long as the boys hold these in their closed hands no one can tell what quantity of counters any boy has; all that can be said is that each boy has some counters. Hence on the black-board is written:—“L has some counters,” “M has some counters,” and so on for each boy. Now the pupils have been accustomed in their arithmetical work to use various shorthand symbols in order to avoid writing out in full frequently occurring words or phrases. Thus, instead of the word “one” we use 1; the expression “multiplied by” is represented by ×, and so on. We therefore rub out the words “five” and “eight” that we wrote at first, and write in place of them their symbols “5” and “8.”
Evaluation of Trigonometrical Ratios of Angles which are not Acute
Authors: Anderson W.
Published: July 2013

The following is meant as a set of working rules for applying the definitions of the trigonometrical ratios of any angle, where numerical evaluation is required. Let the initial arm of the angle be horizontal.
Similar Figures
Authors: Pinkerton P.
Published: July 2013

(1) Let A, B, C represent Aberdeen, Glasgow, Edinburgh respectively on a map of Scotland. Let D, E, F represent the same places in order on a map of Scotland on a different scale. The straight line AB represents the road from Aberdeen to Glasgow, the straight line AC represents the road from Aberdeen to Edinburgh. The angle A represents the angle between these roads. The angle D represents the same angle.
Internal and External Bisectors, and an Example of Continuity
Authors: Pinkerton P.
Published: July 2013

I. To draw quickly a good figure of A, B, C, I, I1, I2, I3, etc. Draw a circle, and a chord BC. Mark L the middle point of the arc below BC by the “engineer's method,” viz., with B as centre and a radius as near BL as can be judged by the eye, make a mark on the arc, with C as centre and the same radius make another mark on the arc, judge by the eye the middle point of the arc between these marks; this is L. With centre L, radius LB or LC, describe a circle: I and I1 lie on this circle. Mark M the middle point of the arc above BC. With centre M, radius MB or MC, describe a circle: I2 and I3 lie on this circle. Now I and I1 lie on AL; I2 and I3 on AM. Mark A on the first circle, so that MA lies conveniently on the paper. The various collinearities and perpendicularities justify the figure to the eye; the properties of the mid-points of II1 etc., I2T3, etc., and the loci of I, I1 I2 I3 as A varies, are emphasised.
A Rule for Resolving Integral Algebraic Expressions into Factors
Authors: Muirhead R. F.
Published: July 2013

Professor Chrystal remarks (Algebra, Chap. VII. §4) that “for tntative processes no general rule can be given.” The tentative processes consist in arranging the terms in groups in such a way as either to manifest a factor common to these groups or aggregates of terms, or to bring the expression under one of the Standard Forms of which the factors are already known, such as a2-b2, a3 - b3, a3 + b3.
Ptolemy's Theorem and certain Trigonometrical Formulæ
Authors: Burgess A. G.
Published: July 2013

Let XOX′ = 1 be the diameter of a circle,

Then the lines representing the sines and cosines of the angles,

are marked in the figure.
Graphical Solution of Equations of the form acosθ + bcosθ = c, without the aid of tables
Authors: Dougall John
Published: July 2013

If P and Q are the common points of this circle and line, then OP and OQ are the bounding radii for the two values of θ, supposing these angles to be traced in the usual way by a revolving radius starting from the position OX.
The Possible Error in a Quotient
Authors: Lindsay W. A.
Published: July 2013

Let the quotient be A ÷ B where the possible errors in A and B respectively are a and b.
The Equality and Inequality of Fractions
Authors: M‘Intosh D. C.
Published: July 2013

In a recent issue ofThe Mathematical Gazette (May 1910), Mr C. S. Jackson points out that certain algebraic theorems appear more difficult to some beginners than would have been anticipated, and he instances as a case in point the proof of the proposition that if , each ratio is equal to . He almost apologises (I think quite unnecessarily) for making the suggestion that some concrete illustrations of the proposition may render its simplicity more manifest, and thus prepare the way for an enunciation of the result in its most general form. The illustration Mr Jackson takes of the above proposition is:

“A regiment of 1000 men contains 130 Yorkshiremen; another of 1200 men contains 156.
Graphical Trisection of Circular Arc
Authors: Davis R. F.
Published: July 2013

Let O be the centre of a given circle of radius a; and OA, OB the containing radii of the are which is to be trisected.
A Puzzle of Dr Whewell's.—
Authors: Mackay J. S.
Published: July 2013

Is the following trifle worthy of a place in your Mathematical Notes ? I came on the puzzle in a volume of the letters of Dr W. Whewell, the well-known Master of Trinity College, Cambridge. At the end of a letter to Professor A. De Morgan, dated 18th January 1859, he says:

“I can express every whole number from 1 to 15 (I think) by means of four nines. Thus Is it worth while working this out further ?”

A note to the letter states that:

“Two more examples from a fragment in Dr Whewell's handwriting will illustrate the meaning of this:

Here are my solutions of the puzzle for the numbers 0 to 40, excepting 38. Some ingenious young mathematician may be instigated to complement my solutions, and to carry the matter still further.
Notes on Algebraic Inequalities.—
Authors: Muirhead R. F.
Published: July 2013

It is worthy of remark that there is a method of proving algebraic inequalities which is very generally applicable, and which furnishes proofs of great directness and completeness.

The method consists in expressing the difference A – B in a manifestly positive form, when we have to prove A > B.

The first inequality occurring in school Algebra is usually proved in this way. We have to show that if a, b, and x are positive quantities is nearer to 1 than . We have

The two cases a > b and b > a are then considered separately, and the conclusion drawn.
On the use of Σ(n) and Σ(n2) in relation to integration
Authors: Stokes G. D. C.
Published: July 2013

The base AB of a right-angled triangle ABC is divided into n equal parts. On these parts as bases n outer rectangles (Fig. 1) and(n–1) inner rectangles (Fig. 2) are drawn. To find Snthe sum of the areas of the outer set and Sn′ the sum of the areas of the inner set.
Two Theorems on Determinants, and their Application to the Proof of the Volume-Formula for Tetrahedra
Authors: Muirhead R. F.
Published: July 2013

Theorem I. If to each of the elements of any row of a determinant there be added the same fraction of the difference between the corresponding elements in two other rows, the value of the determinant is unaltered. This is a case of a well known elementary theorem.
On Extraneous Values in Simultaneous Equations
Authors: Stokes G. D. C.
Published: July 2013

Mr Ridley's note in the January number giving an algebraic explanation of extraneous values suggests an elementary treatment of the subject on the geometrical side. It must be assumed that the pupil is able to trace from their equations straight lines, circles, and parabolas of the type y = ax2 + bx + c. He should be made to draw the curves in cases like those given here, and to state the geometrical meaning of every distinct step in the algebra.
Note on students and original work
Authors: Muirhead R. F.
Published: July 2013

I have sometimes been laughed at when I have ventured the opinion that University students of mathematics ought to do original work in mathematics as part (and an important part) of their degree work. But this will not prevent me from maintaining that original work should be done by every scholar in a junior class of geometry. Of course in one sense this is a mere platitude, for every “problem” and “rider” requires for its solution original work on the part of the scholar. He or she that would solve a geometrical problem must “intend the mind continually” on it, like Sir Isaac Newton, and acquire the faculty of trying different points of view till the right one is found. For him or her, at any rate, the Pragmatists' test of truth is appropriate. He asks of every hypothesis “will it work?” and finds the answer by actual trial.
Note on the Determination of Centres of Curvature
Authors: M'Whan J.
Published: July 2013

For determining the Cartesian co-ordinates of the centre of curvature of a plane curve two methods are principally used in the text-books. One of these (see for example, Edwards, “Differential Calculus,” p 266, § 339) having previously established the formula for the radius of curvature, derives the coordinates of the centre of curvature by using the circular functions of the angle “ψ,” which the tangent to the curve at the point considered makes with OX. Since, however, for the same tangent, and therefore the same “ψ” the curve may be either convex or concave towards OX (and accordingly the centre of curvature have quite different positions), this method introduces an essential ambiguity, and is not to be recommended.
Discrimination of the Roots of a Cubic Equation by Elementary Algebra
Authors: Whan J. M'
Published: July 2013

The following note shows how the conditions for the reality or equality of the roots of a cubic can be obtained from the similar conditions for a quadratic. The method does not involve the use of the calculus or the properties of turning points, nor of the imaginary cube roots of unity.
The Limits of and when n tends to infinity
Authors: Gibson G. A.
Published: July 2013

These limits may be proved very simply by applying the following theorem in inequalities:—

If n is a positive integer and r a a positive proper fraction for the values 1, 2, 3, … n of r, then
Elementary Method of investigating the Centroid of a Uniform Circular Arc
Authors: Sommerville D. M. Y.
Published: July 2013

Let AB and BC be two circular arcs subtending angles 2α and 2β at the common centre 0. From symmetry the centroids G1, G2 and G of AB, BC and AC lie on the bisectors OP, OQ and

OR of the angles which they subtend at the centre. Also, G is the centroid of two particles placed at G1 and G2, and with masses proportional to the arcs AB and BC. Hence G1, G, and G2 are collinear, and

Equating (1) and (2) we have

Hence the ratio is independent of α, and therefore

the angle α. being in circular measure.
Nomogram for the Solution of the Equation z3 + pz + q = 0
Authors: Sommerville D. M. Y.
Published: July 2013

The curve Y = x3 is constructed with a scale of 1″ horizontally and ″ vertically. It is graduated with the values of x. Then draw the two lines x = ± 1 and graduate them on the scale of the y-axis, x = + 1 positive downwards, x = – 1 positive upwards.
Elementary Methods of interpreting the Equation of the first degree in two and three dimensions
Authors: Milne John
Published: July 2013

The following elementary methods of interpreting the equation of the first degree in two and three dimensions may be of some pedagogic interest.
A simple form of Integrometer
Authors: Horsburgh E. M.
Published: July 2013

Most continuously recording instruments are arranged so as to draw a graph exhibiting the quantity measured by means of cartesian coordinates. The record is on a roll of paper unwound from a drum. If the instrument be some form of meter, the value of the output, represented by ∫ y dx, may be obtained by measuring the area by a planimeter. The records, however, are somewhat bulky, and in this respect a polar graph is preferable. This is drawn by an indicator moving radially on a revolving disc. The peak or maximum of the curve is usually the most important, and this is the part which is represented best on such a polar diagram. Space may be further economised by having more than one convolution on one sheet of paper. Polar output records, however, are not freely used, perhaps because the planimeter does not give directly what is wanted, as it measures ½ ∫ r2-dθ, instead of ∫r dθ.
Theorem regarding a regular polygon and a circle cutting its sides, with corollary and application to trigonometry
Authors: Russell Alex D.
Published: July 2013

Theorem.

If a circle cut all the sides (produced if necessary) of a regular polygon, the algebraic sum of the intercepts, on the sides, between the vertices and the circle is zero.
A Theorem on Rational Integral Symmetric Functions
Authors: Dougall John
Published: July 2013

An identity involving symmetric functions of n letters may in a certain class of cases be extended immediately to a greater number of letters.

For example, the theorem

may be written

and in the latter form it is true for any number of letters.
A Problem in Confocals
Authors: Bell Robert J. T.
Published: July 2013

In the standard text books on Analytical Geometry the following problem occurs in the exercises on confocals:

The product of the four normals from a point P to the ellipseX2/a2 + Y2/b2 = 1 is equal to where λ1 and λ2 are the parameters of the confocals through P.
A Simple Method of Finding Sums of Powers of the Natural Numbers
Authors: Etherington I. M. H.
Published: July 2013

Let 1α + 2α + 3α + …. + nα be denoted by Sα. It is well known that Sα can be expressed as a polynomial in n of degree (α + 1). The expressions for S1, S2, S3 …. can be found in succession by elementary methods, which also give numerous relations such as S3 = 12S2S3 = 7S6 + 5S4. The elegant method which I am about to explain is not original. It is due in essence to the Arabian mathematician Alkarkhi (circa 1000 B.C.).
The Probability Distribution of a Bridge Hand
Authors: Marshall J. B.
Published: July 2013

The probability distribution of a bridge hand affords a good example of drawings without replacement from a limited stock.

Let n drawings be made from such a stock. Let prs and qrs be the probabilities of success and failure after there have been r drawings with s successes, and let the probabilities in successive drawings be connected by the relation
A Synthetic Derivation of the Class of the Φ Conic
Authors: Daniels H. E.
Published: July 2013

The theorem that a line cutting a pair of conies in four harmonically separated points envelopes a conic, called the Φ conic, is a familiar result which admits of a simple proof by analytical methods. A synthetic proof, however, if we exclude the use of (2, 2) correspondences, is rather elusive. I have not been able to find such a proof in any book, and the only one published as far as I am aware is that set as a question in the 1934 Mathematical Tripos, due to Mr F. P. White. The proof written out below is rather more direct and may therefore be worth recording.
A Useful Expansion in Applications of Determinants
Authors: Aitken A. C.
Published: July 2013

The expansion, in the form of a series, of the quotient of two determinants, in which the numerator determinant differs from the denominator in one column only, is moderately well known. It was found in 1825 by P. Schweins (see Muir's History, Vol. 1, pp. 171–2), and has many times since been rediscovered or proved ad hoc for particular applications.
On the centre of spherical curvature of a curve
Authors: Weatherburn C. E.
Published: July 2013

The position of the centre S of spherical curvature at a point P of a given curve C may be found in the following manner, regarding S as the limiting position of the centre of a sphere through four adjacent points P, P1, P2, P3 on the curve, as these points tend to coincidence at P. The centre of a sphere through P and P1 lies on the plane which is the perpendicular bisector of the chord PP1 and so on. Thus the centre of spherical curvature is the limiting position of the intersection of three normal planes at adjacent points. Let s be the arc-length of the curve C, r the position vector of the point P, and t, n, b unit vectors in the directions of the tangent, principal normal and binormal at P. Then if s is the position vector of the current point on the normal plane at P, the equation of this plane is

Since r and t are functions of s, the limiting position of the line of intersection of the normal planes at P and an adjacent point (i.e. the polar line) is determined by (1) and the equation obtained by differentiating this with respect to s, viz.
On the Individuality of Sleep EEG Spectra
Authors: Lewandowski Achim , Rosipal Roman , Dorffner Georg
Published: July 2013

Research in recent years has supported the hypothesis that many properties of the electroencephalogram (EEG) are specific to an individual. In this study, the intra- and inter-individual variations of sleep EEG signals were investigated. This was carried out by analyzing the stability of the average EEG spectra individually computed for the Rechtschaffen and Kales (RK) sleep stages. Six EEG channels were used to account for the topographical aspect of the analysis. Validity of the results was supported by considering a wide dataset of 174 subjects with normal sleep. Subjects spent two consecutive nights in the sleep laboratory during which EEG recordings were obtained. High similarity between average spectra of two consecutive nights was found considering an individual. More than 89% of the second night recordings were correctly assigned to their counterparts of the first night. The average spectra of sleep EEG computed for each RK sleep stage have shown a high degree of individuality.
Psychological Responses to Sound Stimuli Evaluated by Alpha Wave Fluctuations
Authors: Chen Xi , Takahashi Isao , Okita Yoshimitsu , Hirata Hisashi , Sugiura Toshifumi
Published: July 2013

Evaluation of psychological stress or state of mind remains an important problem. The anterior asymmetry and emotion model (AAE model) is a conventional and widely used method to sort baseline affective styles (approach or withdrawal) based on asymmetry of the activity in prefrontal cortices. Another method is to use alpha wave fluctuations at the frontal poles, as proposed by Yoshida. This method estimates state of mind as one point on a comfort level surface with pleasant-unpleasant and excited-calm axes that are normal to each other. The aim of this paper is to investigate the validity of the Yoshida method through the psychological responses to sound stimuli. Twenty-two healthy graduate students listened to two kinds of sound clips (scary and soothing) to induce negative and positive emotional states. The results showed that there are significant differences between the responses to scary and soothing sound stimuli in both unpleasant and excited mood states. Compared with baseline, increases in unpleasant and excited mood states were found in response to scary stimuli. However, no significant changes from the baseline state were observed in response to the soothing sound stimulus. These results suggest that the fluctuation of alpha waves recorded at both frontal poles is a valid index for the evaluation of psychological state of mind, especially for negative stimulation. Future study plans include investigating a possible relationship between the AAE model and the Yoshida method.
Aurora A kinase and its substrate TACC3 are required for central spindle assembly
Authors: Lioutas Antonios , Vernos Isabelle
Published: July 2013

Cell division entails a marked reorganization of the microtubule network to form the spindle, a molecular machine that ensures accurate chromosome segregation to the daughter cells. Spindle organization is highly dynamic throughout mitosis and requires the activity of several kinases and complex regulatory mechanisms. Aurora A (AurA) kinase is essential for the assembly of the metaphase bipolar spindle and, thus, it has been difficult to address its function during the last phases of mitosis. Here, we examine the consequences of inhibiting AurA in cells undergoing anaphase, and show that AurA kinase activity is necessary for the assembly of a robust central spindle during anaphase. We also identify TACC3 as an AurA substrate essential in central spindle formation.
On the hydrodynamic interaction between a particle and a permeable surface
Authors: Ramon Guy Z. , Huppert Herbert E. , Lister John R. , Stone Howard A.
Published: July 2013

The motion and deposition of a particle translating perpendicular to a rigid, permeable surface is considered. The lubrication approximation is used to derive an equation for the pressure in the gap between the particle and the permeable surface, with a symmetric shape prescribed for the particle. The hydrodynamic force on a particle is, in general, a function of the particle size and shape, the distance from the surface and the surface permeability, and its sign depends on the relative motion of the particle and the background fluid permeating through the surface. As the particle becomes flatter, this force generally increases and is more sensitive to the surface permeability. In the case of a spherical particle, closed-form, approximate solutions are obtained using perturbation methods, in the limits of small permeability and close approach to contact. It is also shown that a sedimenting particle attains a finite velocity on close approach, which scales as k1/2 and k for a sphere and a disc, respectively, where k is the permeability per unit thickness of the surface. In the case of a particle advected toward the surface, as is common in membrane filtration, a balance of electrostatic repulsion and viscous drag is used to calculate a possible equilibrium position of the particle, at some finite distance from the surface. The dependence of the equilibrium and its stability is shown in terms of the ratio of electrostatic and lubrication forces at contact, as well as the ratio of characteristic lengths over which the two forces decay away from the boundary. The latter is found to be a significant factor in determining the conditions under which a stable equilibrium exists. These results are useful for estimating deposition propensity in membrane filtration processes, as affected by operational conditions.
Defect states and disorder in charge transport in semiconductor nanowires
Authors: Ko Dongkyun , Zhao X. W. , Reddy Kongara M. , Restrepo O. D. , Mishra R. , Lemberger T. R. , Beloborodov I. S. , Trivedi Nandini , Padture Nitin P. , Windl W. , Yang F. Y. , Johnston-Halperin E.
Published: July 2013

We present a comprehensive investigation into disorder-mediated charge transport in InP nanowires in the statistical doping regime. At zero gate voltage, transport is well described by the space charge limited current model and hopping transport, but positive gate voltage (electron accumulation) reveals a previously unexplored regime of nanowire charge transport that is not well described by existing theory. The ability to continuously tune between these regimes provides guidance for the extension of existing models and directly informs the design of next-generation nanoscale electronic devices.
Strain induced variations in band offsets and built-in electric fields in InGaN/GaN multiple quantum wells
Authors: Dong L. , Mantese J. V. , Avrutin V. , Özgür Ü. , Morkoç H. , Alpay S. P.
Published: July 2013

The band structure, quantum confinement of charge carriers, and their localization affect the optoelectronic properties of compound semiconductor heterostructures and multiple quantum wells (MQWs). We present here the results of a systematic first-principles based density functional theory (DFT) investigation of the dependence of the valence band offsets and band bending in polar and non-polar strain-free and in-plane strained heteroepitaxial InxGa1-xN(InGaN)/GaN multilayers on the In composition and misfit strain. The results indicate that for non-polar m-plane configurations with [12¯10]InGaN//[12¯10]GaN and [0001]InGaN//[0001]GaN epitaxial alignments, the valence band offset changes linearly from 0 to 0.57 eV as the In composition is varied from 0 (GaN) to 1 (InN). These offsets are relatively insensitive to the misfit strain between InGaN and GaN. On the other hand, for polar c-plane strain-free heterostructures with [101¯0]InGaN//[101¯0]GaN and [12¯10]InGaN//[12¯10]GaN epitaxial alignments, the valence band offset increases nonlinearly from 0 eV (GaN) to 0.90 eV (InN). This is significantly reduced beyond x ≥ 0.5 by the effect of the equi-biaxial misfit strain. Thus, our results affirm that a combination of mechanical boundary conditions, epitaxial orientation, and variation in In concentration can be used as design parameters to rapidly tailor the band offsets in InGaN/GaN MQWs. Typically, calculations of the built-in electric field in complex semiconductor structures often must rely upon sequential optimization via repeated ab initio simulations. Here, we develop a formalism that augments such first-principles computations by including an electrostatic analysis (ESA) using Maxwell and Poisson's relations, thereby converting laborious DFT calculations into finite difference equations that can be rapidly solved. We use these tools to determine the bound sheet charges and built-in electric fields in polar epitaxial InGaN/GaN MQWs on c-plane GaN substrates for In compositions x = 0.125, 0.25,…, and 0.875. The results of the continuum level ESA are in excellent agreement with those from the atomistic level DFT computations, and are, therefore, extendable to such InGaN/GaN MQWs with an arbitrary In composition.
Shear thinning effects on blood flow in straight and curved tubes
Authors: Cherry Erica M. , Eaton John K.
Published: July 2013

Simulations were performed to determine the magnitude and types of errors one can expect when approximating blood in large arteries as a Newtonian fluid, particularly in the presence of secondary flows. This was accomplished by running steady simulations of blood flow in straight and curved tubes using both Newtonian and shear-thinning viscosity models. In the shear-thinning simulations, the viscosity was modeled as a shear rate-dependent function fit to experimental data. Simulations in straight tubes were modeled after physiologically relevant arterial flows, and flow parameters for the curved tube simulations were chosen to examine a variety of secondary flow strengths. The diameters ranged from 1 mm to 10 mm and the Reynolds numbers from 24 to 1500. Pressure and velocity data are reported for all simulations. In the straight tube simulations, the shear-thinning flows had flattened velocity profiles and higher pressure gradients compared to the Newtonian simulations. In the curved tube flows, the shear-thinning simulations tended to have blunted axial velocity profiles, decreased secondary flow strengths, and decreased axial vorticity compared to the Newtonian simulations. The cross-sectionally averaged pressure drops in the curved tubes were higher in the shear-thinning flows at low Reynolds number but lower at high Reynolds number. The maximum deviation in secondary flow magnitude averaged over the cross sectional area was 19% of the maximum secondary flow and the maximum deviation in axial vorticity was 25% of the maximum vorticity.
Highly-enhanced reflow characteristics of sputter deposited Cu interconnections of large scale integrated devices by optimizing sputtering conditions
Authors: Onishi Takashi , Mizuno Masao , Yoshikawa Tetsuya , Munemasa Jun , Mizuno Masataka , Kihara Teruo , Araki Hideki , Shirai Yasuharu
Published: July 2013

Improving the reflow characteristics of sputtered Cu films was attempted by optimizing the sputtering conditions. The reflow characteristics of films deposited under various sputtering conditions were evaluated by measuring their filling level in via holes. It was found that the reflow characteristics of the Cu films are strongly influenced by the deposition parameters. Deposition at low temperatures and the addition of H2 or N2 to the Ar sputtering gas had a significant influence on the reflow characteristics. Imperfections in the Cu films before and after the high-temperature, high-pressure treatments were investigated by positron annihilation spectroscopy. The results showed that low temperature and the addition of H2 or N2 led to films containing a large number of mono-vacancies, which accelerate atomic diffusion creep and dislocation core diffusion creep, improving the reflow characteristics of the Cu films.
Cathodoluminescence characterization of suspended GaN nanomembranes
Authors: Stevens-Kalceff M. A. , Tiginyanu I. M. , Popa V. , Braniste T. , Brenner P.
Published: July 2013

Continuous suspended ∼15 nm thick gallium nitride (GaN) nano-membranes have been investigated using cathodoluminescence microanalysis. The GaN nanomembranes are fabricated by focused ion beam (FIB) pre-treatment of GaN epilayer surfaces followed by photoelectrochemical (PEC) etching. CL microanalysis enables high sensitivity, nanoscale spatial resolution detection of impurities, and defects, and is associated with key features of the suspended GaN nano-membranes. CL spectra and images of the suspended nano-membranes reveal the broad emission band at ∼2.2 eV which is associated with deep acceptor states and the near edge emission at ∼3.4 eV which is associated with free exciton transitions at 295 K. The near edge emission can be resolved into two components, one associated with emission from the nanomembrane and the other associated with CL from underlying GaN transmitted through the nanomembrane. CL spectroscopy gives insight into the physical properties and optical quality of the suspended GaN nano-membranes. Blue shift of the CL near band edge emission indicates that the suspended GaN nanomembranes exhibit the combined effects of quantum confinement and strain.
Label-free viscosity measurement of complex fluids using reversal flow switching manipulation in a microfluidic channel
Authors: Jun Kang Yang , Ryu Jeongeun , Lee Sang-Joon
Published: July 2013

The accurate viscosity measurement of complex fluids is essential for characterizing fluidic behaviors in blood vessels and in microfluidic channels of lab-on-a-chip devices. A microfluidic platform that accurately identifies biophysical properties of blood can be used as a promising tool for the early detections of cardiovascular and microcirculation diseases. In this study, a flow-switching phenomenon depending on hydrodynamic balancing in a microfluidic channel was adopted to conduct viscosity measurement of complex fluids with label-free operation. A microfluidic device for demonstrating this proposed method was designed to have two inlets for supplying the test and reference fluids, two side channels in parallel, and a junction channel connected to the midpoint of the two side channels. According to this proposed method, viscosities of various fluids with different phases (aqueous, oil, and blood) in relation to that of reference fluid were accurately determined by measuring the switching flow-rate ratio between the test and reference fluids, when a reverse flow of the test or reference fluid occurs in the junction channel. An analytical viscosity formula was derived to measure the viscosity of a test fluid in relation to that of the corresponding reference fluid using a discrete circuit model for the microfluidic device. The experimental analysis for evaluating the effects of various parameters on the performance of the proposed method revealed that the fluidic resistance ratio (RJL/RL, fluidic resistance in the junction channel (RJL) to fluidic resistance in the side channel (RL)) strongly affects the measurement accuracy. The microfluidic device with smaller RJL/RL values is helpful to measure accurately the viscosity of the test fluid. The proposed method accurately measured the viscosities of various fluids, including single-phase (Glycerin and plasma) and oil-water phase (oil vs. deionized water) fluids, compared with conventional methods. The proposed method was also successfully applied to measure viscosities of blood with varying hematocrits, chemically fixed RBCS, and channel sizes. Based on these experimental results, the proposed method can be effectively used to measure the viscosities of various fluids easily, without any fluorescent labeling and tedious calibration procedures.
Extreme ultraviolet induced defects on few-layer graphene
Authors: Gao A. , Rizo P. J. , Zoethout E. , Scaccabarozzi L. , Lee C. J. , Banine V. , Bijkerk F.
Published: July 2013

We use Raman spectroscopy to show that exposing few-layer graphene to extreme ultraviolet (EUV, 13.5 nm) radiation, i.e., relatively low photon energy, results in an increasing density of defects. Furthermore, exposure to EUV radiation in a H2 background increases the graphene dosage sensitivity, due to reactions caused by the EUV induced hydrogen plasma. X-ray photoelectron spectroscopy results show that the sp2 bonded carbon fraction decreases while the sp3 bonded carbon and oxide fraction increases with exposure dose. Our experimental results confirm that even in reducing environment oxidation is still one of the main source of inducing defects.
Plasticity of wheat grain yield is associated with plasticity of ear number
Authors: Sadras V. O. , Rebetzke G. J.
Published: July 2013

Here we propose that the perspective of phenotypic plasticity can enhance our understanding of the role of fertile tillers in accommodating environmental variation. We tested the hypothesis that the plasticity of yield correlates with the plasticity of ear number using free-tillering (–tin) and reduced-tillering (+tin) sister wheat lines in two genetic backgrounds, Lang and Silverstar. Crops were grown in 10 rainfed environments resulting from the combination of seasons, sites, nitrogen rates, and sowing dates. The combination of lines and environments generated a range from 157 to 357 ears m–2 at harvest, and a yield range from 1.9 to 4.2 t ha–1. Plasticity was quantified with two methods, slopes of reaction norms and variance ratios; both methods returned the same ranking of lines for both ear number and yield. The tin allele reduced the plasticity of both ear number and yield in Lang but not in Silverstar. The reduced plasticity associated with the tin allele in Lang had two components: a small reduction in ear number under low-yielding conditions, and a large reduction in the capacity to respond to higher yielding environments. Consistent with our working hypothesis, plasticity of yield and plasticity of ear number were correlated (R2 = 0.81, P = 0.01). Plasticity of ear number was associated with the plasticity of shoot biomass at harvest (R2 = 0.74, P = 0.006), and plasticity of biomass was associated with the plasticity of yield (R2 = 0.86, P = 0.0009). This suggests that the environmental responsiveness of yield was partially mediated by the environmental responsiveness of fertile tillers. We found positive correlations between plasticity of ear number and plasticity of several traits including biomass, radiation-use efficiency and water-use efficiency, and a negative correlation between plasticity of ear number and plasticity of seeds per ear. Ear number per se was unrelated to biomass, radiation-use efficiency, water-use efficiency, and seeds per ear. We conclude that a dual focus on traits per se and their plasticity is a fruitful approach to understand the phenotype, particularly when genotype × environment interaction is large.
Polysaccharide hydrogels with tunable stiffness and provasculogenic properties via α-helix to β-sheet switch in secondary structure
Authors: Forget Aurelien , Christensen Jon , Lüdeke Steffen , Kohler Esther , Tobias Simon , Matloubi Maziar , Thomann Ralf , Shastri V. Prasad
Published: July 2013

Mechanical aspects of the cellular environment can influence cell function, and in this context hydrogels can serve as an instructive matrix. Here we report that physicochemical properties of hydrogels derived from polysaccharides (agarose, κ-carrageenan) having an α-helical backbone can be tailored by inducing a switch in the secondary structure from α-helix to β-sheet through carboxylation. This enables the gel modulus to be tuned over four orders of magnitude (G′ 6 Pa–3.6 × 10
4
Pa) independently of polymer concentration and molecular weight. Using carboxylated agarose gels as a screening platform, we demonstrate that soft-carboxylated agarose provides a unique environment for the polarization of endothelial cells in the presence of soluble and bound signals, which notably does not occur in fibrin and collagen gels. Furthermore, endothelial cells organize into freestanding lumens over 100 μm in length. The finding that a biomaterial can modulate soluble and bound signals provides impetus for exploring mechanobiology paradigms in regenerative therapies.