bluuebunny/crossref_metadata_2025 huggingface dataset:
Principal Quantum Number Dependence for ElectronHydrogen Collisions
Authors: Bubelev V , Bray I , Madison DH , Stelbovics AT
Published: June 2013

Over the last two decades, there has been considerable interest in the electronatom scattering problem. Most of this work has concentrated on elastic scattering and excitation of the lowest energy states. However, due to recent technological advances, it is now becoming possible to examine experimentally the excitation of higher lying states. The important question then concerns whether these higher states contain new information. It has been argued that the scattering amplitudes for electronhelium excitation should scale with principal quantum and thus contain no new information. The purpose of this work is to examine the n-dependence for electronhydrogen scattering. The converged-close-coupling and second-order distortedwave methods have been used to calculate scattering amplitudes for excitation of the n = 2, 3 and 4 levels of the hydrogen atom. The n-dependence of the integrated cross sections, differential cross sections and angular correlation parameters will be discussed for energies from threshold to 500 eV.
Laser Assisted Collisions of Electrons with Metal Vapours
Authors: Teubner PJO , Farrell PM , Karaganov V , Law MR , Suvorov V
Published: June 2013

Three separate experiments are described which use laser radiation to probe the details of electron scattering processes from metal vapour targets. Results from superelastic scattering experiments from calcium are presented. The experiments were carried out at incident energies of 25�7 and 45 eV referred to the ground state. Scattering amplitudes derived from these experiments demonstrate that current theories are inadequate. The coherence of the excitation process has been studied by measuring the total polarisation. It is shown that the excitation process is coherent over the whole kinematic range. Preliminary results from a study of superelastic electron scattering from lithium are discussed where it is shown that a quantum electrodynamical model can be used to describe the optical pumping process in 6Li and 7Li. In addition the first superelastic electron spectrum is presented for experiments on lithium. A stepwise excitation technique is described with which cross sections for the electron impact excitation of the 3d9 4s2 2D state in copper can be measured. The experiments are complicated by the presence of D states in the incident copper beam. The origin of these D states is described as is a modification of the technique which leads to their removal.
Production of Ultrabright Slow Atomic Beams Using Laser Cooling
Authors: Hoogerland MD , Milic D , Lu W , Bachor H-A , Baldwin KGH , Buckman SJ
Published: June 2013

We propose to use a three-step transverse and longitudinal cooling scheme, to compress and collimate a strongly diverging flow of metastable rare gas atoms. Simulations show that an atom beam flux of 1010 8−1 in a small diameter (−1 ) atomic beam could be achieved. This technique can be extremely valuable in many areas of atomic physics, e.g. in (electron) spectroscopy and atomic collision physics where high beam densities are desirable.
Role of an Electron Screened Mott - Schwinger Interaction in the Elastic Scattering of Neutrons
Authors: Alexander N , Amos K
Published: June 2013

The Mott–Schwinger potential arising from the interaction of the magnetic moment of a neutron incident upon the (electric) field of a nucleus has a profound effect upon the cross sections for scattering. The purely nuclear interaction (hadronic plus Mott–Schwinger) leads to a divergence in the spin–flip scattering amplitude at 0° scattering and thus to a divergent total scattering cross section. We demonstrate that the screening of this interaction caused by the atomic electron cloud essentially compensates that divergence so that the scattering cross-section values, to be used for example in reactor moderation calculations, are effectively those given by calculations made without consideration of any Mott–Schwinger potential. However, the forward scattered neutrons remain strongly polarised as a result of the (complete) Mott–Schwinger interaction.
Phase Variation Effect on Proton - Nucleus Elastic Scattering
Authors: A Hassan Mohamed , EA Awd-Allah Hamed , SA Hassan Samia , MA Tag El-Din Ibrahim
Published: June 2013

Proton–deuteron elastic scattering at intermediate and high energies illustrates the importance of the phase variation of the nucleon–nucleon elastic scattering amplitude as in previous work. Two kinds of phase variation are examined. The first is the usual one which is related to free nucleon-free nucleon collisions as suggested by Franco. The second is assumed to be related to the time ordering of multi-scattering processes. The two kinds play similar roles in improving the results. The contributions of both kinds lead to a good fit to the experimental data at the energies considered. The value of the phase variation parameter in each kind (where they are considered together), which gives a good fit to the experimental data, are approximately the same and of order 4 (GeV / c)‾ 2. Also, with relatively small values of the phase variation parameter, the phase variation effect improves the agreement with the experimental data for the p–4He elastic scattering differential cross section at the minimum region in the energy range 97–393 GeV.
Nonlinear Dynamics in Atom Optics
Authors: Chen Wenyu , Dyrting S , Milburn GJ
Published: June 2013

In this paper theoretical work on classical and quantum nonlinear dynamics of cold atoms is reported. The basic concepts in nonlinear dynamics are reviewed and then applied to the motion of atoms in time-dependent standing waves and to the atomic bouncer. We describe the quantum dynamics for the cases of regular and chaotic classical dynamics. The effect of spontaneous emission and external noise is also discussed.
Positron - Hydrogen Scattering at Intermediate Energies
Authors: Mitroy Jim
Published: June 2013

Calculations of positron–hydrogen scattering at intermediate energies up to a maximum energy of 10 Ryd are performed using the close coupling (CC) approach. A large L2 basis of positron–hydrogen channels (28 states) is supplemented by the Ps(1s), Ps(2s) and Ps(2p) channels. The inclusion of the positronium states in the CC expansion leads to a model which can describe most of the physics of the positron–hydrogen system with a reasonable degree of accuracy. In particular, the positronium formation cross section, the total reaction cross section and the ionisation cross section are all in agreement with experiment. The elastic scattering cross section and the cross sections for positron impact excitation of the H(2s) and H(2p) levels are also reported.
Incorporation of Threshold Phenomena in Three-body Coulomb Continuum Wavefunctions
Authors: Berakdar Jamal
Published: June 2013

In this work a three-body Coulomb wavefunction for the description of two continuum electrons moving in the field of a nucleus is constructed such that the Wannier threshold law for double escape is reproduced and the asymptotic Coulomb boundary conditions as well as the Kato cusp conditions are satisfied. It is shown that the absolute value of the total cross section, as well as the spin asymmetry, are well described by the present approach. Further, the excess-energy sharing between the two escaping electrons is calculated and analysed in light of the Wannier theory predictions. This is the first time an analytical three-body wavefunction is presented which is asymptotically exact and capable of describing threshold phenomena.
Collision Integrals for Tensorial Hermite Polynomials in Mixtures of Rarefied Gases and Plasmas
Authors: Suchy Kurt
Published: June 2013

The collision integral of Maxwell's balance equation (equation of change) for tensorial Hermite polynomials is calculated with velocity distribution functions represented as orthogonal expansions of local Maxwellians with respect to these polynomials. Closed expressions are obtained for the tensorial coefficients in the expansion of the collision integral with respect to products of Hermitian moments, i.e. velocity averaged Hermite polynomials. The averages over the collisional kinetic energies are represented by transport collision frequencies with two superscripts, which form a/null-sequence with increasing second superscript.
Electron Recapture near Thresholds
Authors: Waterhouse D. K. , Williams J. F.
Published: June 2013

Electron recapture following photon or electron-impact ionisation near
thresholds attracts considerable interest. A comparison is made of the
information gained from studies utilising different methods of observation
including ion yields, (e, 2e) coincidence, and photo-electron spectroscopy, to
increase understanding of the electron recapture process.
Threshold Behaviour of (e, 2e) Reactions in Classical and Quantum Mechanics
Authors: Friedrich H. , Ihra W. , Meerwald P.
Published: June 2013

Electron impact ionisation of one-electron atoms or ions is well described in
the near threshold region by Wannier’s theory based on estimating the
classical phase space available to two outgoing electrons in the Coulomb field
of the residual ion. The relation between classical dynamics and quantum
mechanics in the near threshold region becomes more complicated and
interesting in ‘non-Wannier situations’, where classical
ionisation is either strictly forbidden or strongly inhibited. This paper
focusses on two examples of such situations, which have been receiving
increasing attention in recent years, namely the s-wave
model and the case where the exponent in Wannier"s law diverges.
Quantum Chaos in Multicharged Ions and Statistical Approach to the Calculation of Electron - Ion Resonant Radiative Recombination
Authors: Gribakin G. F. , Gribakina A. A. , Flambaum V. V.
Published: June 2013

We show that the spectrum and eigenstates of open-shell multicharged atomic
ions near the ionisation threshold are chaotic, as a result of extremely high
level densities of multiply excited electron states (103
eV–1 in Au24+) and
strong configuration mixing. This complexity enables one to use statistical
methods to analyse the system. We examine the dependence of the orbital
occupation numbers and single-particle energies on the excitation energy of
the system, and show that the occupation numbers are described by the
Fermi–Dirac distribution, and the temperature and chemical potential can
be introduced. The Fermi–Dirac temperature is close to the temperature
defined through the canonical distribution. Using a statistical approach we
estimate the contribution of multielectron resonant states to the radiative
capture of low-energy electrons by Au25+ and
demonstrate that this mechanism fully accounts for the
102 times enhancement of the recombination over the
direct radiative recombination, in agreement with recent experimental
observations.
Observation of Fractal Conductance Fluctuations over Three Orders of Magnitude
Authors: Taylor R. P. , Micolich A. P. , Newbury R. , Fromhold T. M. , Tench C. R.
Published: June 2013

Fractal magneto-transport properties of mesoscopic semiconductor billiards are
highly topical. In these studies, the magnetic field range over which fractal
behaviour can be observed is crucial. Previous observations have been limited
to approximately one order of magnitude. We present fractal conductance
fluctuations observed over three orders of magnitude and discuss the physical
conditions required to extend this range.
Intracellular Ca2+ and antioxidant values induced positive effect on fertilisation ratio and oocyte quality of granulosa cells in patients undergoing in vitro fertilisation
Authors: Tola Esra Nur , Mungan Muhittin Tamer , Uğuz Abdülhadi Cihangir , Naziroğlu Mustafa
Published: June 2013

Oxidative stress is important for promoting oocyte maturation and ovulation within the follicle through calcium ion (Ca2+) influx. The relationship between antioxidant and cytosolic Ca2+ levels and oocyte quality and fertilisation rate in the granulosa cells of patients undergoing in vitro fertilisation was investigated. Granulosa cells were collected from 33 patients. Cytosolic free Ca2+ ([Ca2+]i) concentration, lipid peroxidation, reduced glutathione, glutathione peroxidase and oocyte quality were measured in the granulosa cells. The relationship between two drug protocols was also examined (gonadotrophin-releasing hormone antagonist and agonist protocols) and the same parameters investigated. The [Ca2+]i concentration (P < 0.001), glutathione (P < 0.05) and oocyte quality (P < 0.001) values were significantly higher in the fertilised group than in the non-fertilised group, although glutathione peroxidase activity was significantly (P < 0.05) higher in the non-fertilised group than in the fertilised group. The [Ca2+]i concentrations were also higher (P < 0.001) in the good-quality oocyte groups than in the poor-quality oocyte group. There was no correlation between the two drug protocols and investigated parameters. In conclusion, it was observed that high glutathione and cytosolic Ca2+ concentrations in granulosa cells of patients undergoing in vitro fertilisation tended to increase the fertilisation potential of oocytes.
The effect of differing intensities of acute cycling on preadolescent academic achievement
Authors: Duncan Michael , Johnson Andrew
Published: June 2013

The present study examined the effects of differing intensity levels of acute exercise on preadolescent academic ability. In a repeated measures design, 18 preadolescent participants (mean age±S.D.=9.8±1.4 years: 9 male and 9 female) completed the Wide Range Achievement Test (WRAT 4) following 20 minutes of rest, 20‐minutes on a cycling ergometer at 50% maximal heart rate reserve (HRR), and 20‐minutes on a cycling ergometer at 75% HRR on separate days. Exercise was found to improve spelling irrespective of intensity level. Moderate levels of exercise improved reading although the effect of high levels of intensity is less clear. Both intensity levels impaired arithmetic, whilst sentence comprehension was unaffected. These findings further support the past research that indicates acute bouts of exercise can selectively improve cognition in preadolescent children. However, the present study finds no support for the notion that increasing the intensity of exercise accentuates benefits.
T cell regulation of natural killer cells
Authors: Kerdiles Yann , Ugolini Sophie , Vivier Eric
Published: June 2013

In light of their role in the immune response against tumors and viruses, natural killer (NK) cells represent a promising target for immunotherapy. Before this target is reached, the various mechanisms that control NK cell activity must first be identified and understood. In the past decades, studies have identified two critical processes that prevent spontaneous NK cell–mediated autoimmune activation while maximizing the efficiency of these cells during an immune response. First is the education process, whereby NK cells adapt to their environment by sensing ligands for inhibitory and activating receptors. Second is the priming phase of NK cell activation, which arms NK cells with appropriate cytotoxic molecules during inflammation. New studies now indicate that NK cell proliferation, accumulation, and activation are also under the control of regulatory T cells that restrict availability of IL-2 released by activated CD4+ T cells. Together with other recent studies, these data highlight the importance of the adaptive immune system in the regulation of NK cell activity.
The Disappearance of an Author and the Emergence of a Genre: Niccolò da Poggibonsi and Pilgrimage Guidebooks between Manuscript and Print*
Authors: Moore Kathryn Blair
Published: June 2013

While the anonymousViaggio da Venetia al Sancto Sepolchro et al Monte Sinai,first published in Venice in 1518, was the most popular Holy Land guidebook in Renaissance Italy, the historical origins of the book have never been fully understood. From four illustrated versions of an earlier manuscript guide, theLibro d’Oltramare(1346–50), one can hypothesize about both the text and its author. The ultimate prototype for theViaggio da Venetiawas very likely one or more of these illustrated manuscripts, and the original author of both the text and illustrations was the Franciscan pilgrim Niccolò da Poggibonsi. Despite the eventual erosion of his name from the printed versions of the guidebook, the assertiveness and originality of the author parallels the production of other vernacular literature in mid-fourteenth-century Italy. Unlike Latin guidebooks of previous centuries, the intent to include illustrations that re-create the pilgrimage experience and the unprecedented descriptiveness of the prose together suggest that the book can be considered the foundational text for the genre of the illustrated pilgrimage guidebook.
Visible Lives: Black Gondoliers and Other Black Africans in Renaissance Venice*
Authors: Lowe Kate
Published: June 2013

This article contributes to the study of the early sub-Saharan African diaspora in Europe by analyzing both visual and documentary evidence relating to black gondoliers in Renaissance Venice. Gondolas and gondoliers were iconic features in fifteenth-century Venice, yet most gondoliers were not Venetian. Although black Africans were highly visible in a predominantly white society, naming practices and linguistic usages rendered them virtually invisible in the documentary sources. It is now possible not only to investigate representations of black gondoliers in paintings, but also to identify black gondoliers in the lists of gondoliers’ associations and in criminal records. Slavery was an accepted institution in late medieval Italy, and nearly all black Africans arrived in Venice as slaves, yet usually ended their lives free. Being a gondolier gave a few black Africans a niche occupation that allowed them to manage their transition to freedom, and to integrate successfully into Venetian society.
“Lend a Voice”: The Humanistic Portrait Epigraph in the Age of Erasmus and Dürer*
Authors: Vredeveld Harry
Published: June 2013

In the early 1500s, a genre of portraiture emerged in Northern Europe that combines bust portraits of humanistic intellectuals and patrons with elegant Latin and Greek epigraphs. While the likenesses have long had the benefit of expert attention, the same cannot always be said of the inscriptions. In consequence, many questions still go begging. It remains unknown, for example, who wrote these anonymous texts; whether the artists composed any of them and (if not) whether they got the wording right; and what exactly the epigraphs intend to say, or what models and conventions they follow. This article aims to supply some answers for the earliest and most influential of the collaborative portraits: Burgkmair’s two woodcuts of Konrad Celtis; Metsys’s medallion of Erasmus; Cranach’s painting of Christoph Scheurl and his three Luther engravings; Dürer’s engravings of Albrecht of Brandenburg, Frederick the Wise, Willibald Pirckheimer, and Philip Melanchthon; and Holbein’s paintings of Bonifacius Amerbach, Erasmus, and Melanchthon.
Current Surgical Guidelines
Authors: Jibawi Abdullah , Cade David
Published: June 2013

Current Surgical Guidelines covers the main conditions requiring surgical care, such as breast cancer, critically ill surgical patients, and diverticular disease, and focuses on the evidence and selection criteria which determine the best action to take. Recommendations are graded according to relevant current guidelines and all benefits/risk decision recommendations are supported by easy-to-digest facts and figures.
How to Build a Two-Photon Microscope with a Confocal Scan Head
Authors: Nikolenko Volodymyr , Yuste Rafael
Published: June 2013

This article provides practical guidelines for the conversion of a standard confocal microscope into a two-photon microscope. This conversion enables the investigator to have access to two-photon microscopy without the large budget necessary to purchase a commercial instrument. Two-photon fluorescence microscopy allows deep-tissue imaging in highly scattering preparations and long-term imaging of live tissue without the photodamage that is caused by out-of-focus light. It is, therefore, an essential tool for imaging cells under physiologically relevant conditions such as acute or cultured brain slices or in vivo.
Cycling Assay for Determining Intracellular Cyclic ADP-Ribose Levels
Authors: Bruzzone Santina , Guse Andreas H.
Published: June 2013

Cyclic ADP-ribose (cADPR) is a Ca2+-mobilizing second messenger involved in the regulation of various physiological processes. The ability to detect changes in endogenous cADPR is a fundamental step in the identification of its role in signal transduction triggered by hormones and other stimuli. Because the intracellular concentration of cADPR can be very low, depending on the expression level of the ADP-ribosyl cyclase activity (forming cADPR and nicotinamide from NAD) in the cell type of interest, very sensitive and selective methods are required. The method presented here exploits the ability of the ADP-ribosyl cyclase to catalyze the reverse reaction (i.e., to synthesize NAD stoichiometrically starting from cADPR) in the presence of an excess of nicotinamide. The generation of NAD can be coupled to a cycling assay using the enzymes alcohol dehydrogenase and diaphorase. The former reduces NAD to NADH in the presence of ethanol and the latter oxidizes NADH to NAD in the presence of resazurin and flavin mononucleotide. The formation of the fluorescent reduced resazurin (resofurin) can be detected with a plate reader. Thus, this cycling assay for cADPR determination can be considered a high-throughput method, potentially screening cADPR concentration simultaneously in many samples.
Measuring Leukocyte-Endothelial Interactions in Mice
Authors: Jain Rakesh K. , Munn Lance L. , Fukumura Dai
Published: June 2013

Intravital imaging techniques are powerful tools in the study of tumor pathophysiology. These techniques can be used to measure vascular parameters (e.g., angiogenesis, hemodynamics, and leukocyte-endothelial interactions) in tumors and normal vascular networks in mice. This protocol describes the use of single-photon microscopy and multiphoton laser-scanning microscopy to follow the migration of Rhodamine-6G, a fluorescently labeled tracer, following injection into the tail vein of a mouse. The Rhodamine-6G enters the circulatory system and labels leukocytes. It is possible to monitor changes in the interactions between leukocytes and the endothelium by determining the numbers of rolling and adhering leukocytes as well as the total flux of these cells.
Imaging Green Fluorescent Protein-Labeled Neurons Using Light and Electron Microscopy
Authors: Knott Graham W.
Published: June 2013

The ability to observe axons and dendrites with transmission electron microscopy (EM) after they have been previously imaged live with laser-scanning microscopy is a useful technique to study their synaptic connectivity. This protocol provides a detailed method by which neurons that were imaged in a live brain or slice culture can be reimaged using EM. First, brain tissue expressing green fluorescent protein (GFP) is chemically fixed. Then, an immunocytochemistry process is used to render the fluorescent protein electron dense so that it can first be located using light microscopy and then serial thin-sectioned for EM so that the ultrastructure of specific parts of neurites can be analyzed in three dimensions. Patterns of blood vessels observed in the live brain are used to locate the previously imaged neurons. The method described here allows for a complete three-dimensional (3D) reconstruction to be made of the imaged structures from serial electron micrographs.
Purification and Culture of Astrocytes
Authors: Foo Lynette C.
Published: June 2013

For years, studies of neural–glial interactions have relied on the use of astrocytes derived from the extended culture of immature precursor cells isolated from the neonatal rodent brain. Although the astrocytes cultured under these selective cell survival conditions have been important tools for understanding astrocyte behavior, they do not necessarily reflect the behavior and function of mature astrocytes. We have developed methods for acute, prospective isolation and culture of mature astrocytes from rodent brains in a serum-free, defined medium. These immunopanning-based methods facilitate the study of astrocyte biology and function.
Stochastic Optical Reconstruction Microscopy (STORM): A Method for Superresolution Fluorescence Imaging
Authors: Bates Mark , Jones Sara A. , Zhuang Xiaowei
Published: June 2013

The relatively low spatial resolution of the optical microscope presents significant limitations for the observation of biological ultrastructure. Subcellular structures and molecular complexes essential for biological function exist on length scales from nanometers to micrometers. When observed with light, however, structural features smaller than ∼0.2 µm are blurred and are difficult or impossible to resolve. In this article, we describe stochastic optical reconstruction microscopy (STORM), a method for superresolution imaging based on the high accuracy localization of individual fluorophores. It uses optically switchable fluorophores: molecules that can be switched between a nonfluorescent and a fluorescent state by exposure to light. The article discusses photoswitchable fluorescent molecules, STORM microscope design and the imaging procedure, data analysis, imaging of cultured cells, multicolor STORM, and three-dimensional (3D) STORM. This approach is generally applicable to biological imaging and requires relatively simple experimental apparatus; its spatial resolution is theoretically unlimited, and a resolution improvement of an order of magnitude over conventional optical microscopy has been experimentally demonstrated.
Effects of maternal age and mass on foraging behaviour and foraging success in the northern elephant seal
Authors: Hassrick Jason L. , Crocker Daniel E. , Costa Daniel P.
Published: June 2013

Animals that show indeterminate growth and put relatively constant proportions of stored body reserves towards annual reproductive effort are confronted with a problem of meeting ever‐increasing energetic demands in unpredictable environments.

We examined how intrinsic traits, mass and age, as well as extrinsic environmental features impact diving and movement behaviour in a marine capital breeder, the northern elephant seal,Mirounga angustirostris. We assessed the impact of this behavioural variation on foraging success, measured as energy gained at sea.

We used principal component analysis to reduce behavioural variables into three principal components that described time in foraging zones (PC1), foraging distance (PC2) and bout structure of dive shapes (PC3).

Both intrinsic traits and extrinsic environmental features influenced behaviour and foraging success. Body mass was the sole predictor of residence time in foraging zones (PC1), which, in turn, was the strongest behavioural predictor of foraging efficiency and success over the short postbreeding season. Foraging distance (PC2) significantly varied with year. Since foraging distance is an index of the horizontal and vertical distances seals travel while foraging, we suggest that it was impacted by inter‐annual variation in marine prey distribution. Age had a negligible impact on most aspects of behaviour, except for the structure of dive shapes on the postmoult foraging trip.

All principal components significantly impacted rates of energy gain for postbreeding foraging trips when maternal body stores must be recovered quickly before returning to shore to moult. Age impacted the bout structure of dives in pregnant females in a way that influenced success, suggesting a role for previous experience during the long postmoult foraging migration.

Strong impacts of body mass on diving ability, foraging success and reproductive effort suggest a proximate mechanism for trade‐offs in the cost of reproduction. Mass lost to current investment in offspring impacts a mother's ability to accrue resources for future offspring.
Contrasting effects of plant inter‐ and intraspecific variation on community‐level trait measures along an environmental gradient
Authors: Kichenin Emilie , Wardle David A. , Peltzer Duane A. , Morse Chris W. , Freschet Grégoire T.
Published: June 2013

Despite widespread focus on interspecific variation in trait‐based ecology, there is growing evidence that intraspecific trait variability can play a fundamental role in plant community responses to environmental change and community assembly.

Here, we quantify the strength and direction of inter‐ and intraspecific plant community trait responses along a 900 m elevation gradient spanning alpine and subalpine plant communities in southern New Zealand. We measured five commonly used leaf traits (i.e. dry matter content, N and P concentrations, leaf area and specific leaf area) on all 31 dominant and subordinate species recorded along the gradient, and examined their species‐specific and community‐level responses to elevation using both abundance‐weighted and nonweighted averages of trait values.

By decomposing the variance of community‐level measures of these traits across the gradient, we showed that the contribution of interspecific variation to the response of plant assemblages to elevation was stronger than that of intraspecific variation, for all traits except specific leaf area. Further, the relative contributions of interspecific effects were greater when abundance‐weighted rather than nonweighted measures were used. We also observed contrasting intraspecific trait responses to the gradient among species (particularly for leaf N and P concentrations), and found both positive and negative covariation between inter‐ and intraspecific effects on community‐level trait values.

The weak community‐average trait responses to elevation, as found for specific leaf area (SLA) and leaf N and P concentrations, resulted from strong but opposing responses among vs. within species, which are not typically accounted for in species‐based measures of plant community responses. For instance, increasing elevation (and associated factors such as a decrease in soil nutrient availability) favoured the dominance of species with relatively high leaf nutrient concentrations while simultaneously triggering an intraspecific decrease in the leaf nutrient concentrations of these species.

The context dependency of positive and negative covariation between inter‐ and intraspecific trait variability, and the species‐specific nature of intraspecific shifts in functional trait values, reveal highly complex plastic responses of plants to environmental changes, and highlights the need for greater consideration of the role that intraspecific variation plays in community‐level processes.
Foraging currencies, metabolism and behavioural routines
Authors: Houston Alasdair I. , McNamara John M.
Published: June 2013

A fundamental issue in foraging theory is whether it is possible to find a simple currency that characterizes foraging behaviour. If such a currency exists, then it is tempting to argue that the selective forces that have shaped the evolution of foraging behaviour have been understood.

We review previous work on currencies for the foraging behaviour of an animal that maximizes total energy gained. In many circumstances, it is optimal to maximize a suitably modified form of efficiency.

We show how energy gain, predation and damage can be combined in a single currency based on reproductive value.

We draw attention to the idea that hard work may have an adverse effect on an animal's condition. We develop a model of optimal foraging over a day when a forager's state consists of its energy reserves and its condition. Optimal foraging behaviour in our model depends on energy reserves, condition and time of day. The pattern of optimal behaviour depends strongly on assumptions about the probability that the forager is killed by a predator.

If condition is important, no simple currency characterizes foraging behaviour, but behaviour can be understood in terms of the maximization of reproductive value. It may be optimal to adopt a foraging option that results in a rate of energy expenditure that is less than the rate associated with maximizing efficiency.
The distribution of below‐ground traits is explained by intrinsic species differences and intraspecific plasticity in response to root neighbours
Authors: Valverde‐Barrantes Oscar J. , Smemo Kurt A. , Feinstein Larry M. , Kershner Mark W. , Blackwood Christopher B.
Published: June 2013

Large variation in tree root architecture and morphology has been reported for temperate forest communities. However, it is not clear whether this variation represents adaptation of species to specific soil properties, alternative resource acquisition strategies among co‐occurring species, or canalized traits without a strong impact on the success of individuals in different environments. Here, our goal was to test these alternative hypotheses and quantify how community‐aggregated and intraspecific root trait variations are explained by biotic versus abiotic mechanisms in a temperate deciduous forest.

We conducted our study in an Acer‐Fagus‐dominated forest in north‐east Ohio, USA. Using molecular barcoding techniques, we identified 738 root systems belonging to 14 tree species. We measured seven functional root traits related to root architecture and morphology at the species and community‐aggregated levels.

Although we found significant relationships between soil resource gradients and root trait distributions, intrinsic differences between coexisting species were more important than soil factors in explaining the distribution of root traits in the community. Additionally, root trait variation at the species level was also influenced by the presence of other species within cores.

Community‐aggregated variation was more influenced by the combination of species present than soil properties in each sample, suggesting that biotic interactions play an important role in controlling community root trait distribution.

Synthesis. We propose that root trait differentiation between coexisting species is the result of inherent differences between species and plasticity‐mediated responses to neighbours. Hence, the large variation in root traits reported in temperate forest seems to reflect alternative evolutionary pathways that allow individuals to exploit distinct niches in relatively close proximity.
Photoperiod length paces the temporal orchestration of cell cycle and carbon‐nitrogen metabolism in Crocosphaera watsonii
Authors: Dron Anthony , Rabouille Sophie , Claquin Pascal , Talec Amélie , Raimbault Virginie , Sciandra Antoine
Published: June 2013

We analysed the effect of photoperiod length (PPL) (16:8 and 8:16 h of light–dark regime, named long and short PPL, respectively) on the temporal orchestration of the two antagonistic, carbon and nitrogen acquisitions in the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii strain WH8501 growing diazotrophically. Carbon and nitrogen metabolism were monitored at high frequency, and their patterns were compared with the cell cycle progression. The oxygen‐sensitive N2 fixation process occurred mainly during the dark period, where photosynthesis cannot take place, inducing a light–dark cycle of cellular C : N ratio. Examination of circadian patterns in the cell cycle revealed that cell division occurred during the midlight period, (8 h and 4 h into the light in the long and short PPL conditions, respectively), thus timely separated from the energy‐intensive diazotrophic process. Results consistently show a nearly 5 h time lag between the end of cell division and the onset of N2 fixation. Shorter PPLs affected DNA compaction of C. watsonii cells and also led to a decrease in the cell division rate. Therefore, PPL paces the growth of C. watsonii: a long PPL enhances cell division while a short PPL favours somatic growth (biomass production) with higher carbon and nitrogen cell contents.
The Gac/Rsm and cyclic‐di‐GMP signalling networks coordinately regulate iron uptake in Pseudomonas aeruginosa
Authors: Frangipani Emanuela , Visaggio Daniela , Heeb Stephan , Kaever Volkhard , Cámara Miguel , Visca Paolo , Imperi Francesco
Published: June 2013

Pseudomonas aeruginosa is a versatile bacterial pathogen capable of occupying diverse ecological niches. To cope with iron limitation, P. aeruginosa secretes two siderophores, pyoverdine and pyochelin, whose ability to deliver iron to the cell is crucial for biofilm formation and pathogenicity. In this study, we describe a link between iron uptake and the Gac/Rsm system, a conserved signal transducing pathway of P. aeruginosa that controls the production of extracellular products and virulence factors, as well as the switch from planktonic to biofilm lifestyle. We have observed that pyoverdine and pyochelin production in P. aeruginosa is strongly dependent on the activation state of the Gac/Rsm pathway, which controls siderophore regulatory and biosynthetic genes at the transcriptional level, in a manner that does not involve regulation of ferric uptake regulator (Fur) expression. Gac/Rsm‐mediated regulation of iron uptake genes appears to be conserved in different P. aeruginosa strains. Further experiments led to propose that the Gac/Rsm system regulates siderophore production through modulation of the intracellular levels of the second messenger c‐di‐GMP, indicating that the c‐di‐GMP and the Gac/Rsm regulatory networks essential for biofilm formation can also coordinately control iron uptake in P. aeruginosa.
Metabolic flexibility of enigmatic SAR324 revealed through metagenomics and metatranscriptomics
Authors: Sheik Cody S. , Jain Sunit , Dick Gregory J.
Published: June 2013

Chemolithotrophy is a pervasive metabolic lifestyle for microorganisms in the dark ocean. The SAR324 group of Deltaproteobacteria is ubiquitous in the ocean and has been implicated in sulfur oxidation and carbon fixation, but also contains genomic signatures of C1 utilization and heterotrophy. Here, we reconstructed the metagenome and metatranscriptome of a population of SAR324 from a hydrothermal plume and surrounding waters in the deep Gulf of California to gain insight into the genetic capability and transcriptional dynamics of this enigmatic group. SAR324's metabolism is signified by genes that encode a novel particulate hydrocarbon monooxygenase (pHMO), degradation pathways for corresponding alcohols and short‐chain fatty acids, dissimilatory sulfur oxidation, formate dehydrogenase (FDH) and a nitrite reductase (NirK). Transcripts of the pHMO, NirK, FDH and transporters for exogenous carbon and amino acid uptake were highly abundant in plume waters. Sulfur oxidation genes were also abundant in the plume metatranscriptome, indicating SAR324 may also utilize reduced sulfur species in hydrothermal fluids. These results suggest that aspects of SAR324's versatile metabolism (lithotrophy, heterotrophy and alkane oxidation) operate simultaneously, and may explain SAR324's ubiquity in the deep Gulf of California and in the global marine biosphere.
A carbon responsive G‐protein coupled receptor modulates broad developmental and genetic networks in the entomopathogenic fungus, Beauveria bassiana
Authors: Ying Sheng‐Hua , Feng Ming‐Guang , Keyhani Nemat O.
Published: June 2013

In fungi, G‐protein coupled receptors (GPCRs) link ligand/nutrient sensing to growth, mating, developmental/life‐stage activation and pathogenesis. A GPCR was characterized from the entomopathogenic fungus, Beauveria bassiana (BbGPCR3), which links nutrient sensing to stress response and development. ΔBbGPCR3 mutants grew slower on various carbohydrates and displayed increased sensitivity to osmotic, oxidative and cell wall stresses. Gene expression profiling revealed a set of heat‐shock and antioxidant factors that failed to be induced under oxidative stress and aberrant regulation of compatible solute‐forming enzymes and cell wall biosynthesis/remodelling proteins in ΔBbGPCR3 after osmotic stress. Glucose‐specific developmental defects included reduced (> 90%) conidiation and reduced dimorphic transition to the production of yeast‐like blastospores, effects suppressed in media containing trehalose or glycerol, but not by addition of cyclic AMP. Insect bioassays revealed reduced virulence in topical assays but no effect in intrahaemoceol injection assays, indicating that BbGPCR3 was important in sensing signals during the initial interaction with the host but dispensable for post‐penetration events. Comparative gene expression profiling of ΔBbGPCR3 mutants grown in glucose media compared with wild‐type/glucose and ΔBbGPCR3/trehalose grown cells revealed sets of genes misregulated and recovered, respectively. These data link BbGPCR3 to broad developmental and genetic networks that include the major MAP kinase pathways.
Capillary electrophoresis–mass spectrometry reveals the distribution of carbon metabolites during nitrogen starvation in Synechocystis sp. PCC 6803
Authors: Osanai Takashi , Oikawa Akira , Shirai Tomokazu , Kuwahara Ayuko , Iijima Hiroko , Tanaka Kan , Ikeuchi Masahiko , Kondo Akihiko , Saito Kazuki , Hirai Masami Yokota
Published: June 2013

Nitrogen availability is one of the most important factors for the survival of cyanobacteria. Previous studies on Synechocystis revealed a contradictory situation with regard to metabolism during nitrogen starvation; that is, glycogen accumulated even though the expressions of sugar catabolic genes were widely upregulated. Here, we conducted transcript and metabolomic analyses using capillary electrophoresis–mass spectrometry on Synechocystis sp. PCC 6803 under nitrogen starvation. The levels of some tricarboxylic acid cycle intermediates (succinate, malate and fumarate) were greatly increased by nitrogen deprivation. Purine and pyrimidine nucleotides were markedly downregulated under nitrogen depletion. The levels of 19 amino acids changed under nitrogen deprivation, especially those of amino acids synthesized from pyruvate and phosphoenolpyruvate, which showed marked increases. Liquid chromatography–mass spectrometry analysis demonstrated that the amount of NADPH and the NADPH/NADH ratio decreased under nitrogen depletion. These data demonstrate that there are increases in not only glycogen but also in metabolites downstream of sugar catabolism in Synechocystis sp. PCC 6803 under nitrogen starvation, resolving the contradiction between glycogen accumulation and induction of sugar catabolic gene expression in this unicellular cyanobacterium.
Fertiliser Subsidies and Smallholder Commercial Fertiliser Purchases: Crowding Out, Leakage and Policy Implications for Zambia
Authors: Mason Nicole M. , Jayne Thomas S.
Published: June 2013

Fertiliser intended for government subsidy programmes is sometimes diverted and sold to farmers at or near market prices. Failure to account for such ‘leakage’ can upwardly bias econometric estimates of the effect of government fertiliser subsidy programmes on total fertiliser use. This paper extends the framework used in earlier studies on the crowding in/crowding out effects of subsidised fertiliser on commercial fertiliser purchases to account for leakage, and then applies it to the case of Zambia. Results suggest that each additional kg of subsidised fertiliser injected into the system increases total fertiliser use by 0.54 kg. Without controlling for leakage, the estimate would have been 0.87, an overestimate of 61%.
Total lunchtime fast food purchases were lower in sodium and saturated fat when nutritionally promoted fast foods were ordered instead of traditional fast foods: A pilot study
Authors: Antoniolli Rachel E. , Atkinson Louise F. , Palmer Michelle A.
Published: June 2013

Aim

The aim of the study was to compare sodium and saturated fat contents of lunchtime fast food orders containing regular items with those containing items promoted for nutritional attributes (e.g. Subway sandwiches containing 6 g fat or less, McDonald's Heart Foundation Tick approved range).

Methods

In March–April 2010, 907 McDonald's and Subway lunchtime customers (aged 25(16–84) years, 59% M, 73% response rate) in Queensland, Australia were surveyed. Sodium and saturated fat contents of orders were calculated using information from company websites. Independent samples t‐ and chi‐squared tests were used to assess whether orders including nutritionally promoted fast foods contained less sodium and saturated fat, and a chi‐squared test to compare the proportion of customers at each store whose orders exceeded the daily sodium upper limit (2300 mg).

Results

Proportionately more customers ordering nutritionally promoted fast foods (n = 24) ordered meals containing ≤1300 mg sodium and ≤6 g saturated fat (83% and 92%, respectively) than those ordering regular fast foods (n = 883, 33% and 24%, respectively, P < 0.02). One‐quarter (24%) of orders—all selected from the regular menu—exceeded the daily sodium upper limit. Proportionately more orders from Subway (40%) exceeded the daily sodium upper limit than from McDonald's (5%, P < 0.001).

Conclusions

Lunchtime fast food orders may contain less sodium and saturated fat when nutritionally promoted foods are selected. Reformulating all fast foods may be warranted given that fast foods contain high levels of sodium and saturated fat, and nutritionally promoted fast foods may represent only a small proportion of lunchtime choices.
Diehard Conservatism, Mass Democracy, and Indian Constitutional Reform, c.1918–35
Authors: Fleming N.C.
Published: June 2013

This article explores the Conservative Party crisis over India to examine the relationship between diehard Conservatives and Britain's emerging democracy. Far from rejecting democracy outright, diehard rhetoric and mass communication demonstrates how they adapted to it and utilised it in pursuit of their objectives. The accommodation of diehard Conservatism within the Conservative Party was a necessary and mutual embrace. Contrary to popular image, it promoted Conservative unity and contributed to the party's remarkable electoral success. Unable to exact decisive victories, the capacity of diehard Conservatives to generate party crises over imperial questions, among grass‐roots and back‐bench Conservatives, ensured that they had a role in shaping the presentation and content of party policy. This had implications for leadership efforts to liberalise the party, and also popular perceptions of British imperialism and the feasibility of democracy in India.
Parliament, the Church of England and the Last Gasp of Political Protestantism, 1963–4
Authors: Maiden John , Webster Peter
Published: June 2013

Political protestantism has been an enduring theme in parliamentary and ecclesiastical politics and has had considerable influence on modern Church and state relations. Since the mid 19th century, evangelicals have sought to apply external and internal pressure on parliament to maintain the ‘protestant identity’ of the national Church, and as late as 1928, the house of commons rejected anglican proposals for the revision of the prayer book. This article examines the attempts by evangelicals to prevent the passage through parliament of controversial measures relating to canon law revision in 1963–4. It assesses the interaction between Church and legislature, the influence of both evangelical lobbyists and MPs, and the terms in which issues relating to religion and national identity were debated in parliament. It shows that while evangelicals were able to stir up a surprising level of controversy over canon law revision – enough for the Conservative Party chief whip, Selwyn Lloyd, to attempt to persuade Archbishop Ramsey to delay introducing the vesture of ministers measure to parliament until after the 1964 general election – the influence of political protestantism, and thus a significant long‐term theme in British politics, had finally run its course.