bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathophysiological mechanisms of high-intensity focused ultrasound-mediated vascular occlusion and relevance to non-invasive fetal surgery
Authors: Shaw C. J. , ter Haar G. R. , Rivens I. H. , Giussani D. A. , Lees C. C.
Published: March 2014

High-intensity focused ultrasound (HIFU) is a non-invasive technology, which can be used occlude blood vessels in the body. Both the theory underlying and practical process of blood vessel occlusion are still under development and relatively sparse
in vivo
experimental and therapeutic data exist. HIFU would however provide an alternative to surgery, particularly in circumstances where serious complications inherent to surgery outweigh the potential benefits. Accordingly, the HIFU technique would be of particular utility for fetal and placental interventions, where open or endoscopic surgery is fraught with difficulty and likelihood of complications including premature delivery. This assumes that HIFU could be shown to safely and effectively occlude blood vessels
in utero
. To understand these mechanisms more fully, we present a review of relevant cross-specialty literature on the topic of vascular HIFU and suggest an integrative mechanism taking into account clinical, physical and engineering considerations through which HIFU may produce vascular occlusion. This model may aid in the design of HIFU protocols to further develop this area, and might be adapted to provide a non-invasive therapy for conditions in fetal medicine where vascular occlusion is beneficial.
Single-site sonoporation disrupts actin cytoskeleton organization
Authors: Chen Xian , Leow Ruen Shan , Hu Yaxin , Wan Jennifer M. F. , Yu Alfred C. H.
Published: March 2014

Sonoporation is based upon an ultrasound–microbubble cavitation routine that physically punctures the plasma membrane on a transient basis. During such a process, the actin cytoskeleton may be disrupted in tandem because this network of subcellular filaments is physically interconnected with the plasma membrane. Here, by performing confocal fluorescence imaging of single-site sonoporation episodes induced by ultrasound-triggered collapse of a single targeted microbubble, we directly observed immediate rupturing of filamentary actin (F-actin) at the sonoporation site (cell type: ZR-75-30; ultrasound frequency: 1 MHz; peak negative pressure: 0.45 MPa; pulse duration: 30 cycles; bubble diameter: 2–4 µm). Also, through conducting a structure tensor analysis, we observed further disassembly of the F-actin network over the next 60 min after the onset of sonoporation. The extent of F-actin disruption was found to be more substantial in cells with higher uptake of sonoporation tracer. Commensurate with this process, cytoplasmic accumulation of globular actin (G-actin) was evident in sonoporated cells, and in turn the G-actin : F-actin ratio was increased in a trend similar to drug-induced (cytochalasin D) actin depolymerization. These results demonstrate that sonoporation is not solely a membrane-level phenomenon: organization of the actin cytoskeleton is concomitantly perturbed.
Herpes simplex virus-2 transmission probability estimates based on quantity of viral shedding
Authors: Schiffer Joshua T. , Mayer Bryan T. , Fong Youyi , Swan David A. , Wald Anna
Published: March 2014

Herpes simplex virus (HSV)-2 is periodically shed in the human genital tract, most often asymptomatically, and most sexual transmissions occur during asymptomatic shedding. It would be helpful to identify a genital viral load threshold necessary for transmission, as clinical interventions that maintain viral quantity below this level would be of high utility. However, because viral expansion, decay and re-expansion kinetics are extremely rapid during shedding episodes, it is impossible to directly measure genital viral load at the time of sexual activity. We developed a mathematical model based on reproducing shedding patterns in transmitting partners, and median number of sex acts prior to transmission in discordant couples, to estimate infectivity of single viral particles in the negative partner's genital tract. We then inferred probability estimates for transmission at different levels of genital tract viral load in the transmitting partner. We predict that transmission is unlikely at viral loads less than 10
4
HSV DNA copies. Moreover, most transmissions occur during prolonged episodes with high viral copy numbers. Many shedding episodes that result in transmission do not reach the threshold of clinical detection, because the ulcer remains very small, highlighting one reason why HSV-2 spreads so effectively within populations.
Understanding macroalgal dispersal in a complex hydrodynamic environment: a combined population genetic and physical modelling approach
Authors: Brennan Georgina , Kregting Louise , Beatty Gemma E. , Cole Claudia , Elsäßer Björn , Savidge Graham , Provan Jim
Published: March 2014

Gene flow in macroalgal populations can be strongly influenced by spore or gamete dispersal. This, in turn, is influenced by a convolution of the effects of current flow and specific plant reproductive strategies. Although several studies have demonstrated genetic variability in macroalgal populations over a wide range of spatial scales, the associated current data have generally been poorly resolved spatially and temporally. In this study, we used a combination of population genetic analyses and high-resolution hydrodynamic modelling to investigate potential connectivity between populations of the kelp
Laminaria digitata
in the Strangford Narrows, a narrow channel characterized by strong currents linking the large semi-enclosed sea lough, Strangford Lough, to the Irish Sea. Levels of genetic structuring based on six microsatellite markers were very low, indicating high levels of gene flow and a pattern of isolation-by-distance, where populations are more likely to exchange migrants with geographically proximal populations, but with occasional long-distance dispersal. This was confirmed by the particle tracking model, which showed that, while the majority of spores settle near the release site, there is potential for dispersal over several kilometres. This combined population genetic and modelling approach suggests that the complex hydrodynamic environment at the entrance to Strangford Lough can facilitate dispersal on a scale exceeding that proposed for
L. digitata
in particular, and the majority of macroalgae in general. The study demonstrates the potential of integrated physical–biological approaches for the prediction of ecological changes resulting from factors such as anthropogenically induced coastal zone changes.
The Lie point symmetry generators admitted by systems of linear differential equations
Authors: Gray Robert J.
Published: March 2014

Computing the Lie point symmetries of
systems
of linear differential equations can be prohibitively difficult. For homogeneous systems in Kovalevskaya form of order two or higher, this paper proves the existence of a basis of infinitesimal generators (as determined by Lie's algorithm) whose characteristic forms are homogeneous in the dependent variables of degree zero, one or two. Suppose Lie's algorithm yields a characteristic form of degree two; in this case, the system is second order. If it contains only ordinary differential equations (ODEs), its general solution is constructed from those of a given
first-order
linear homogeneous system, of the same dimension, and a second-order linear
scalar
equation. Otherwise, coordinates are given in which its dimension (necessarily two or higher now) is lowered by one, leaving an inhomogeneous system of parametrized ODEs. Its homogeneous part is solved as in the previous case.
How could the Viking Sun compass be used with sunstones before and after sunset? Twilight board as a new interpretation of the Uunartoq artefact fragment
Authors: Bernáth Balázs , Farkas Alexandra , Száz Dénes , Blahó Miklós , Egri Ádám , Barta András , Åkesson Susanne , Horváth Gábor
Published: March 2014

Vikings routinely crossed the North Atlantic without a magnetic compass and left their mark on lands as far away as Greenland, Newfoundland and Baffin Island. Based on an eleventh-century dial fragment artefact, found at Uunartoq in Greenland, it is widely accepted that they sailed along chosen latitudes using primitive Sun compasses. Such instruments were tested on sea and proved to be efficient hand-held navigation tools, but the dimensions and incisions of the Uunartoq find are far from optimal in this role. On the basis of the sagas mentioning sunstones, incompatible hypotheses were formed for Viking solar navigation procedures and primitive skylight polarimetry with dichroic or birefringent crystals. We describe here a previously unconceived method of navigation based on the Uunartoq artefact functioning as a ‘twilight board’, which is a combination of a horizon board and a Sun compass optimized for use when the Sun is close to the horizon. We deduced an appropriate solar navigation procedure using a twilight board, a shadow-stick and birefringent crystals, which bring together earlier suggested methods in harmony and provide a true skylight compass function. This could have allowed Vikings to navigate around the clock, to use the artefact dial as a Sun compass during long parts of the day and to use skylight polarization patterns in the twilight period. In field tests, we found that true north could be appointed with such a medieval skylight compass with an error of about ±4° when the artificially occluded Sun had elevation angles between +10° and −8° relative to the horizon. Our interpretation allows us to assign exact dates to the gnomonic lines on the artefact and outlines the schedule of the merchant ships that sustained the Viking colony in Greenland a millennium ago.
Occam's Razor in sensorimotor learning
Authors: Genewein Tim , Braun Daniel A.
Published: March 2014

A large number of recent studies suggest that the sensorimotor system uses probabilistic models to predict its environment and makes inferences about unobserved variables in line with Bayesian statistics. One of the important features of Bayesian statistics is Occam's Razor—an inbuilt preference for simpler models when comparing competing models that explain some observed data equally well. Here, we test directly for Occam's Razor in sensorimotor control. We designed a sensorimotor task in which participants had to draw lines through clouds of noisy samples of an unobserved curve generated by one of two possible probabilistic models—a simple model with a large length scale, leading to smooth curves, and a complex model with a short length scale, leading to more wiggly curves. In training trials, participants were informed about the model that generated the stimulus so that they could learn the statistics of each model. In probe trials, participants were then exposed to ambiguous stimuli. In probe trials where the ambiguous stimulus could be fitted equally well by both models, we found that participants showed a clear preference for the simpler model. Moreover, we found that participants’ choice behaviour was quantitatively consistent with Bayesian Occam's Razor. We also show that participants’ drawn trajectories were similar to samples from the Bayesian predictive distribution over trajectories and significantly different from two non-probabilistic heuristics. In two control experiments, we show that the preference of the simpler model cannot be simply explained by a difference in physical effort or by a preference for curve smoothness. Our results suggest that Occam's Razor is a general behavioural principle already present during sensorimotor processing.
Personality drives physiological adjustments and is not related to survival
Authors: Bijleveld Allert I. , Massourakis Georgina , van der Marel Annemarie , Dekinga Anne , Spaans Bernard , van Gils Jan A. , Piersma Theunis
Published: March 2014

The evolutionary function and maintenance of variation in animal personality is still under debate. Variation in the size of metabolic organs has recently been suggested to cause and maintain variation in personality. Here, we examine two main underlying notions: (i) that organ sizes vary consistently between individuals and cause consistent behavioural patterns, and (ii) that a more exploratory personality is associated with reduced survival. Exploratory behaviour of captive red knots (Calidris canutus, a migrant shorebird) was negatively rather than positively correlated with digestive organ (gizzard) mass, as well as with body mass. In an experiment, we reciprocally reduced and increased individual gizzard masses and found that exploration scores were unaffected. Whether or not these birds were resighted locally over the 19 months after release was negatively correlated with their exploration scores. Moreover, a long-term mark–recapture effort on free-living red knots with known gizzard masses at capture confirmed that local resighting probability (an inverse measure of exploratory behaviour) was correlated with gizzard mass without detrimental effects on survival. We conclude that personality drives physiological adjustments, rather than the other way around,and suggest that physiological adjustments mitigate the survival costs of exploratory behaviour. Our results show that we need to reconsider hypotheses explaining personality variation based on organ sizes and differential survival.
Environmental heterogeneity affects the location of modelled communities along the niche–neutrality continuum
Authors: Bar-Massada Avi , Kent Rafi , Carmel Yohay
Published: March 2014

The continuum hypothesis has been proposed as a means to reconcile the contradiction between the niche and neutral theories. While past research has shown that species richness affects the location of communities along the niche–neutrality continuum, there may be extrinsic forces at play as well. We used a spatially explicit continuum model to quantify the effects of environmental heterogeneity, comprising abundance distribution and spatial configuration of resources, on the degree of community neutrality. We found that both components of heterogeneity affect the degree of community neutrality and that species' dispersal characteristics affect the neutrality–heterogeneity relationship. Narrower resource abundance distributions decrease neutrality, while spatial configuration, which is manifested by spatial aggregation of resources, decreases neutrality at higher aggregation levels. In general, the degree of community neutrality was affected by complex interactions among spatial configuration of resources, their abundance distributions and the dispersal characteristics of species in the community. Our results highlight the important yet overlooked role of the environment in dictating the location of communities along the hypothesized niche–neutrality continuum.
The dynamics of recovery and growth: how defoliation affects stored resources
Authors: Atkinson R. R. L. , Burrell M. M. , Rose K. E. , Osborne C. P. , Rees M.
Published: March 2014

Growth rate varies widely among species and the trade-off between growth rate and storage or maintenance traits is a principal axis of variation between species. Many plant species have substantial root stores, but very little is known about how growth rate modifies responses of these stores to defoliation and other stresses. Species with different growth rates are predicted to respond in distinct ways, because of variation in the pre-defoliation allocation to storage. Here, we quantified the dynamics of stored carbohydrates in seven species with varying growth rate, following defoliation in a pot experiment. For faster growing species, there was significant reduction in carbohydrate concentration following defoliation, followed by relatively fast recovery, whereas for slower growing species, carbohydrate concentration levels remained relatively invariant across treatments. Results for total carbohydrates mirrored those for concentration, but were not as significant. Our findings were consistent with the idea that faster growing species respond more rapidly than slower growers to defoliation, through changes in carbohydrate pool concentrations. Growth rate as an indicator of life-history and ecological strategy may therefore be key to understanding post-defoliation recovery and storage strategies.
Sexual selection on protamine and transition nuclear protein expression in mouse species
Authors: Lüke Lena , Campbell Polly , Varea Sánchez María , Nachman Michael W. , Roldan Eduardo R. S.
Published: March 2014

Post-copulatory sexual selection in the form of sperm competition is known to influence the evolution of male reproductive proteins in mammals. The relationship between sperm competition and regulatory evolution, however, remains to be explored. Protamines and transition nuclear proteins are involved in the condensation of sperm chromatin and are expected to affect the shape of the sperm head. A hydrodynamically efficient head allows for fast swimming velocity and, therefore, more competitive sperm. Previous comparative studies in rodents have documented a significant association between the level of sperm competition (as measured by relative testes mass) and DNA sequence evolution in both the coding and promoter sequences of protamine 2. Here, we investigate the influence of sexual selection on protamine and transition nuclear protein mRNA expression in the testes of eight mouse species that differ widely in levels of sperm competition. We also examined the relationship between relative gene expression levels and sperm head shape, assessed using geometric morphometrics. We found that species with higher levels of sperm competition express less protamine 2 in relation to protamine 1 and transition nuclear proteins. Moreover, there was a significant association between relative protamine 2 expression and sperm head shape. Reduction in the relative abundance of protamine 2 may increase the competitive ability of sperm in mice, possibly by affecting sperm head shape. Changes in gene regulatory sequences thus seem to be the basis of the evolutionary response to sexual selection in these proteins.
Into turbulent air: size-dependent effects of von Kármán vortex streets on hummingbird flight kinematics and energetics
Authors: Ortega-Jimenez Victor M. , Sapir Nir , Wolf Marta , Variano Evan A. , Dudley Robert
Published: March 2014

Animal fliers frequently move through a variety of perturbed flows during their daily aerial routines. However, the extent to which these perturbations influence flight control and energetic expenditure is essentially unknown. Here, we evaluate the kinematic and metabolic consequences of flight within variably sized vortex shedding flows using five Anna's hummingbirds feeding from an artificial flower in steady control flow and within vortex wakes produced behind vertical cylinders. Tests were conducted at three horizontal airspeeds (3, 6 and 9 m s−1) and using three different wake-generating cylinders (with diameters equal to 38, 77 and 173% of birds' wing length). Only minimal effects on wing and body kinematics were demonstrated for flight behind the smallest cylinder, whereas flight behind the medium-sized cylinder resulted in significant increases in the variances of wingbeat frequency, and variances of body orientation, especially at higher airspeeds. Metabolic rate was, however, unchanged relative to that of unperturbed flight. Hummingbirds flying within the vortex street behind the largest cylinder exhibited highest increases in variances of wingbeat frequency, and of body roll, pitch and yaw amplitudes at all measured airspeeds. Impressively, metabolic rate under this last condition increased by up to 25% compared with control flights. Cylinder wakes sufficiently large to interact with both wings can thus strongly affect stability in flight, eliciting compensatory kinematic changes with a consequent increase in flight metabolic costs. Our findings suggest that vortical flows frequently encountered by aerial taxa in diverse environments may impose substantial energetic costs.
Characterization of the growth dynamics and biofilm formation of Staphylococcus epidermidis strains isolated from contaminated platelet units
Authors: Ali Hamza , Greco-Stewart Valerie S. , Jacobs Michael R. , Yomtovian Roslyn A. , Rood Ineke G. H. , de Korte Dirk , Ramírez-Arcos Sandra M.
Published: March 2014

Bacterial contamination of platelet concentrates (PCs) poses the highest transfusion-associated infectious risk, with Staphylococcus epidermidis being a predominant contaminant. Herein, the growth dynamics of 20 S. epidermidis strains in PCs and regular media were characterized. Strains were categorized as fast (short lag phase) or slow (long lag phase) growers in PCs. All strains were evaluated for the presence of the biofilm-associated icaAD genes by PCR, their capability to produce extracellular polysaccharide (slime) on Congo red agar plates and their ability to form surface-attached aggregates (biofilms) in glucose-supplemented trypticase soy broth (TSBg) using a crystal violet staining assay. A subset of four strains (two slow growers and two fast growers) was further examined for the ability for biofilm formation in PCs. Two of these strains carried the icAD genes, formed slime and produced biofilms in TSBg and PCs, while the other two strains, which did not carry icaAD, did not produce slime or form biofilms in TSBg. Although the two ica-negative slime-negative strains did not form biofilms in media, they displayed a biofilm-positive phenotype in PCs. Although all four strains formed biofilms in PCs, the two slow growers formed significantly more biofilms than the fast growers. Furthermore, growth experiments of the two ica-positive strains in plasma-conditioned platelet bags containing TSBg revealed that a slow grower isolate was more likely to escape culture-based screening than a fast grower strain. Therefore, this study provides novel evidence that links S. epidermidis biofilm formation with slow growth in PCs and suggests that slow-growing biofilm-positive S. epidermidis would be more likely to be missed with automate culture.
Human pegivirus RNA is found in multiple blood mononuclear cells in vivo and serum-derived viral RNA-containing particles are infectious in vitro
Authors: Chivero Ernest T. , Bhattarai Nirjal , Rydze Robert T. , Winters Mark A. , Holodniy Mark , Stapleton Jack T.
Published: March 2014

Human pegivirus (HPgV; previously called GB virus C/hepatitis G virus) has limited pathogenicity, despite causing persistent infection, and is associated with prolonged survival in human immunodeficiency virus-infected individuals. Although HPgV RNA is found in and produced by T- and B-lymphocytes, the primary permissive cell type(s) are unknown. We quantified HPgV RNA in highly purified CD4+ and CD8+ T-cells, including naïve, central memory and effector memory populations, and in B-cells (CD19+), NK cells (CD56+) and monocytes (CD14+) using real-time reverse transcription-PCR. Single-genome sequencing was performed on viruses within individual cell types to estimate genetic diversity among cell populations. HPgV RNA was present in CD4+ and CD8+ T-lymphocytes (nine of nine subjects), B-lymphocytes (seven of ten subjects), NK cells and monocytes (both four of five). HPgV RNA levels were higher in naïve (CD45RA+) CD4+ cells than in central memory and effector memory cells (P<0.01). HPgV sequences were highly conserved among subjects (0.117±0.02 substitutions per site; range 0.58–0.14) and within subjects (0.006±0.003 substitutions per site; range 0.006–0.010). The non-synonymous/synonymous substitution ratio was 0.07, suggesting a low selective pressure. Carboxyfluorescein succinimidyl ester (CFSE)-labelled HPgV RNA-containing particles precipitated by a commercial exosome isolation reagent delivered CSFE to uninfected monocytes, NK cells and T- and B-lymphocytes, and HPgV RNA was transferred to PBMCs with evidence of subsequent virus replication. Thus, HPgV RNA-containing serum particles including microvesicles may contribute to delivery of HPgV to PBMCs in vivo, explaining the apparent broad tropism of this persistent human RNA virus.
Preparation of next-generation DNA sequencing libraries from ultra-low amounts of input DNA: Application to single-molecule, real-time (SMRT) sequencing on the Pacific Biosciences RS II
Authors: Raley Castle , Munroe David , Jones Kristie , Tsai Yu-Chih , Guo Yan , Tran Bao , Gowda Sujatha , Troyer Jennifer L. , Soppet Daniel R , Stewart Claudia , Stephens Robert , Chen Jack , Skelly TF , Heiner Cheryl , Korlach Jonas , Nissley Dwight
Published: March 2014

We have developed and validated an amplification-free method for generating DNA sequencing libraries from very low amounts of input DNA (500 picograms – 20 nanograms) for singlemolecule sequencing on the Pacific Biosciences (PacBio) RS II sequencer. The common challenge of high input requirements for single-molecule sequencing is overcome by using a carrier DNA in conjunction with optimized sequencing preparation conditions and re-use of the MagBead-bound complex. Here we describe how this method can be used to produce sequencing yields comparable to those generated from standard input amounts, but by using 1000-fold less starting material.
A new theory for X-ray diffraction
Authors: Fewster Paul F.
Published: March 2014

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the `Bragg position' even if the `Bragg condition' is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many `Bragg positions'. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on `Bragg-type' scatter. The role of dynamical effects (extinctionetc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the `background'. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models.
Seedling resistance, tolerance and escape from herbivores: insights from co‐dominant canopy tree species in a resource‐poor African rain forest
Authors: Norghauer Julian M. , Glauser Gaëtan , Newbery David M.
Published: March 2014

Although plants can reduce the impacts of herbivory in multiple ways, these defensive traits are often studied in isolation and an understanding of the resulting strategies is incomplete.

In the study reported here, empirical evidence was simultaneously evaluated for the three main sets of traits available to plants: (i) resistance through constitutive leaf traits, (ii) tolerance to defoliation and (iii) escape in space, for three caesalpiniaceous tree species Microberlinia bisulcata, Tetraberlinia bifoliolata and T. korupensis, which co‐dominate groves within the lowland primary rain forest of Korup National Park (Cameroon).

Mesh cages were placed around individual wild seedlings to exclude insect herbivores at 41 paired canopy gap and understorey locations. After following seedling growth and survival for c. 2 years, caged and control treatments were removed, leaves harvested to determine nutrient and phenolic concentrations, leaf mass per area estimated, and seedling performance in gaps followed for a further c. 2 years to quantify tolerance to the leaf harvesting.

The more nutrient‐rich leaves of the weakly shade‐tolerant M. bisulcata were damaged much more in gaps than the two strongly shade‐tolerant Tetraberlinia species, which had higher leaf mass per area and concentrations of total phenols. Conversely, the faster‐growing M. bisulcata was better able to tolerate defoliation in terms of height growth (reflushing capacity), but not at maintaining overall leaf numbers, than the other two species.

Across gaps, insect‐mediated Janzen–Connell effects were most pronounced for M. bisulcata, less so for T. korupensis, and not detectable for T. bifoliolata. The three species differed distinctly in their secondary metabolic profiles.

Taken together, the results suggested a conceptual framework linking the three sets of traits, one in which the three co‐dominant species adopt different strategies towards herbivore pressure depending on their different responses to light availability. This study is one of the first in a natural forest ecosystem to examine resistance to, tolerance of, and escape from herbivory among a group of co‐occurring tropical tree species.
Earlier leaf‐out rather than difference in freezing resistance puts juvenile trees at greater risk of damage than adult trees
Authors: Vitasse Yann , Lenz Armando , Hoch Günter , Körner Christian
Published: March 2014

In temperate climates, seedlings and saplings have often been assumed to be more sensitive to late‐spring freezes than conspecific adult trees. Yet, no data are available to compare the freezing resistance of juvenile and adult trees at their phenologically most sensitive stage, that is, during leaf‐out.

Emerging leaves of seedlings, saplings and adult trees were collected in spring 2013 in seven temperate tree species in a mature mixed forest in the foothills of the Swiss Jura Mountains. Freezing resistance of these emerging leaves was assessed using different target temperatures (−13 to +4 °C) in seven computer‐controlled freezers. Additionally, we assessed the risk that species encounter freeze damages based on temperature data recorded since 1898.

The different study species showed contrasting freezing resistance, with the LT50 (median lethal freezing temperature) of emerging leaves ranging from −3.5 ± 0.2 °C (Fraxinus excelsior) to −8.3 ± 0.2 °C (Prunus avium). Within species, juvenile trees (seedlings or saplings) were found to be as sensitive to freezing temperatures as mature trees when the same developmental stage of foliage was compared. Based on phenological observations made during spring 2012, long time series of temperatures indicate a very low risk of freeze damage at the study site, especially for adult trees.

Synthesis. We conclude that seedlings and saplings are more prone to freeze damage than adult trees because of their earlier flushing rather than due to a higher sensitivity to freezing as such. Our study highlights that the timing of spring phenology has evolved in such a way that it minimizes the risk of freeze damage according to the species‐specific LT50. Early flushing species are among the most freezing‐resistant species during flushing, whereas late flushing species are among the least resistant. We conclude that for the examined species the species‐specific freezing resistance during leaf emergence could be extracted from either adult or juvenile trees, as long as it is estimated at a same phenological stage.
Personal oral narratives in a special school curriculum: an analysis of key documents
Authors: Grove Nicola
Published: March 2014

Oral narrative is a critical skill for school achievement, for personal relationships and for social participation. However, it is downgraded in current and proposed National Curriculum frameworks, which fail to recognise its significance in development. Schools have flexibility to address the issue, which is of particular importance to pupils with special educational needs. This article explores the place of narrative in the policies, curriculum and assessment scheme of a special school catering for pupils across the range of ability. It is concluded that, while schools are free to prioritise according to pupils' needs, it is difficult to target oral narrative effectively in the absence of appropriate frameworks for setting goals and monitoring progress.
Neither confirmed nor denied: special school provision in New Zealand's Special Education 2000 policy
Authors: McMenamin Trish
Published: March 2014

Special Education 2000 (SE2000), New Zealand's first official special education policy, declared the aim of achieving a ‘world class inclusive education system’. It would seem that, by implication at least, the intention of the policy was to achieve full inclusion of all disabled children in mainstream educational settings and thus, consequentially, the demise of separate special school provision. Given this, it would be fair to expect that intentions with respect to special school provision would feature prominently in the policy. However, surprisingly, this was not the case; only brief references to special school provision can be found in the policy material and certainly nothing that would constitute a clearly articulated policy objective for this type of provision. In this article, Trish McMenamin of the University of Canterbury, New Zealand, argues that a plausible explanation for this somewhat curious absence is that the differing ideological premises of inclusion and neoliberalism that underpinned SE2000 served as boundaries to what could be said and thought in that context and at that time. This, it is suggested, led to a policy position in which a role for special schools could neither be confirmed nor denied.
Extracellular matrix is modulated in advanced glycation end products milieu via a RAGE receptor dependent pathway boosted by transforming growth factor‐β1 在晚期糖基化终末产物环境中细胞外基质通过RAGE受体依赖性途径调节，转化生长因子‐β1可以促进这种调节
Authors: Serban Andreea Iren , Stanca Loredana , Geicu Ovidiu Ionut , Munteanu Maria Cristina , Costache Marieta , Dinischiotu Anca
Published: March 2014

Background

Interstitial fibrosis is induced by imbalances in extracellular matrix homeostasis. Advanced glycation end products (AGEs) can bind and activate the receptor for AGEs (RAGE), which is involved in diabetic nephropathy. We set out to identify the role of AGEs in producing alterations leading to matrix hypertrophy and the pathway through which aminoguanidine, as well as anti‐RAGE and anti‐transforming growth factor (TGF)‐β1 antibody treatments could prevent these modifications.

Methods

Human embryonic kidney (HEK‐293) cells were exposed to glycated bovine serum albumin (AGE‐BSA) and co‐treated with neutralizing antibodies or aminoguanidine. The effects on the transcriptional and translational levels of RAGE, TGF‐β1 and collagen IV were evaluated, while metalloproteinase activity was assessed by gelatin zymography.

Results

AGE‐BSA (200 μg/mL) upregulated RAGE's expression, while TGF‐β1 synthesis and the formation of its bioactive form were increased in a dose‐dependent manner by AGEs. AGE‐BSA exposure increased both matrix metalloproteinase (MMP) activity and collagen IV synthesis, boosted by TGF‐β1 upregulation. Aminoguanidine's effects revealed that small concentrations (10 μmol/L) enhance AGE‐BSA effects, by increasing the expression of RAGE and TGF‐β1, while higher concentrations (100 μmol/L) contribute to their downregulation.

Conclusions

Although AGEs regulate RAGE and TGF‐β1 by distinct pathways, RAGE activation leads to a further increase of TGF‐β1 levels. MMP‐2 activity seems to rely on TGF‐β1, while MMP‐9 was dependent on RAGE. These factors converge to control collagen IV turnover. Furthermore, although the antibody treatments might appear more efficient than AG in decreasing collagen IV levels, the cells compensate the RAGE and TGF‐β1 blockade by increasing the mRNA expression of these proteins.
Rheumatoid factor in idiotypic regulation of autoimmunity
Authors: Beduleva Liubov , Menshikov Igor , Stolyarova Elena , Fomina Kseniya , Lobanova Olga , Ivanov Pavel , Terentiev Alexey
Published: March 2014

Aim

Rheumatoid factor (RF) is known to be heterogeneous, and RFs detected by various methods exhibit different characteristics. In addition to interacting with the Fc region of immunoglobulin G (IgG), certain RFs are able to recognize idiotypes of antibodies. Given the important role of idiotypic interactions in regulating autoimmunity, we hypothesize that RF is involved in regulation of lymphocyte activity against autoimmune disease‐inducing antigens via idiotype–anti‐idiotype interactions with these lymphocytes.

Method

RF level and the existence of idiotype–anti‐idiotype interactions between RF and antibodies to autoimmunity‐inducing antigens were studied in rats resistant and sensitive to collagen‐induced arthritis, encephalomyelitis and atherosclerosis. RF was assayed by agglutination of tanned IgG‐loaded erythrocytes.

Results

Rat resistance to autoimmune disease is associated with high RF production during the initiation of the immune response, and a low RF level during this period may be a preclinical marker of experimental autoimmune disease manifestation. RF‐containing sera compete with an antigen if the RF‐containing sera were obtained from rats immunized with that antigen, and they non‐specifically inhibit binding of different antigen‐antibody pairs. This suggests that RFs are anti‐idiotypic antibodies that carry two kinds of paratopes: a particular paratope that recognizes the antigen‐binding sites of antibodies, and a shared paratope that serves to recognize the recurrent idiotype on antibodies. Antigenic epitopes for the shared RF paratope can be created in the hinge region of Fc fragments of homologous IgG.

Conclusion

RF detected by agglutination of tanned IgG‐loaded erythrocytes is involved in negative idiotypic regulation of lymphocytes specific to autoimmunity‐inducing antigens.
Market structure and gender disparity in health care: preferences, competition, and quality of care
Authors: McDevitt Ryan C. , Roberts James W.
Published: March 2014

We consider the relationship between market structure and health outcomes in a setting where patients have stark preferences: urology patients disproportionately match with a urologist of the same gender. In the United States, however, fewer than 6% of urologists are women despite women constituting 30% of patients. We explain a portion of this disparity with a model of imperfect competition in which urology groups strategically differentiate themselves by employing female urologists. These strategic effects may influence women's health, as markets without a female urologist have a 7.3% higher death rate for female bladder cancer, all else equal.
Calling circles: network competition with nonuniform calling patterns
Authors: Hoernig Steffen , Inderst Roman , Valletti Tommaso
Published: March 2014

We introduce a flexible model of telecommunications network competition with nonuniform calling patterns, accounting for the fact that customers tend to make most calls to a small set of similar people. Equilibrium call prices are distorted away from marginal cost, and competitive intensity is affected by the concentration of calling patterns. Contrary to previous predictions, jointly profit‐maximizing access charges are set above termination cost in order to dampen competition if calling patterns are sufficiently concentrated. We discuss implications for regulating access charges as well as on‐ and off‐net price discrimination.
Rapid assessment of wildlife abundance: estimating animal density with track counts using body mass–day range scaling rules
Authors: Keeping D.
Published: March 2014

Limited resources in conservation dictate the need for efficient means of assessing wildlife abundance. Body mass–day range scaling rules and empirical track counts were applied to an established formula to estimate a wide range of wildlife densities. Using the southern Kalahari ecosystem of Botswana as an example, I provide the first comprehensive density estimates for the mammalian wildlife community (>0.2 kg), including densities for several species previously unattainable by other methods. Among a subset of species, empirical day ranges from this area were consistently greater than those predicted using scaling rules modeled with species from diverse ecosystems. I applied a correction factor based on this discrepancy, which generated values congruent with independent density estimates from the area. Although accurate measures of day range are a practical constraint to estimating densities from track counts, the results suggest that modest efforts to obtain location‐specific day range estimates for a subset of species can improve density estimates for others derived from general allometric relationships. Given the strength of track surveys to accumulate unbiased observations quickly, in environments where animal tracks are readily visible, this approach shows potential for the rapid assessment of wildlife abundance.
Predictors of extinction risk of passerine birds in aCentralEuropean country
Authors: Koleček J. , Albrecht T. , Reif J.
Published: March 2014

To develop effective conservation measures, it is crucial that we understand how ecological and life‐history traits relate to risk of species extinction. Through the use of phylogenetic generalized least‐squares regression, this study assesses the relative importance of habitat specialization, life history, migration strategy and climatic niche as predictors of national threat level for 86 passerine bird species breeding in theCzechRepublic. We found that, after controlling for variation in breeding distribution, slow life history increases the extinction risk in habitat specialist species, but reduces such risk in habitat generalists. The higher threat of habitat specialists is consistent with their higher sensitivity to human‐induced environmental perturbations, most notably to the habitat loss. However, our results suggest that the negative effects of habitat specialization appear to be somewhat compensated for by fast life history. For example, species with fast life histories typically display higher fecundity than species with slow life histories. At the same time, slow life history can be beneficial for habitat generalists that are not as badly affected by habitat destruction as habitat specialists. Such species are able to allocate more energy to future reproduction and could wait for optimal environmental conditions before breeding, leading to more favourable population status in the long term. Finally, we also found that species breeding in warmer areas experience higher extinction risk than species breeding in colder areas. Although the effect of climatic niche is usually attributed to the impact of climate change, we suggest that the habitat destruction is more likely an explanation because the warmer lowland regions are heavily exploited by intensive agriculture and industrial and urban development. Based upon these results, we suggest that current conservation effort, especially in warmer zones, may not sufficiently address the requirements of the habitat specialists with slow histories.
Effects of inhalational anaesthetics in experimental allergic asthma
Authors: Burburan S. M. , Silva J. D. , Abreu S. C. , Samary C. S. , Guimarães I. H. L. , Xisto D. G. , Morales M. M. , Rocco P. R. M.
Published: March 2014

We evaluated whether isoflurane, halothane and sevoflurane attenuate the inflammatory response and improve lung morphofunction in experimental asthma. Fifty‐six BALB/c mice were sensitised and challenged with ovalbumin and anaesthetised with isoflurane, halothane, sevoflurane or pentobarbital sodium for one hour. Lung mechanics and histology were evaluated. Gene expression of pro‐inflammatory (tumour necrosis factor‐α), pro‐fibrogenic (transforming growth factor‐β) and pro‐angiogenic (vascular endothelial growth factor) mediators, as well as oxidative process modulators, were analysed. These modulators included nuclear factor erythroid‐2 related factor 2, sirtuin, catalase and glutathione peroxidase. Isoflurane, halothane and sevoflurane reduced airway resistance, static lung elastance and atelectasis when compared with pentobarbital sodium. Sevoflurane minimised bronchoconstriction and cell infiltration, and decreased tumour necrosis factor‐α, transforming growth factor‐β, vascular endothelial growth factor, sirtuin, catalase and glutathione peroxidase, while increasing nuclear factor erythroid‐2‐related factor 2 expression. Sevoflurane down‐regulated inflammatory, fibrogenic and angiogenic mediators, and modulated oxidant–antioxidant imbalance, improving lung function in this model of asthma.
How Finance Penetrates its Other: A Cautionary Tale on the Financialization of a Dutch University
Authors: Engelen Ewald , Fernandez Rodrigo , Hendrikse Reijer
Published: March 2014

If any organization ought to be immune to the forces of financialization, it is a publicly funded university in corporatist Europe. Shielded from the intrusion by financial metrics, values and professionals through a strong historically rooted tradition of self‐management by powerful professional guilds, continental universities should largely have avoided the marketization and managerialization of Anglophone universities. Not so, this case study of a Dutch public university suggests. From 1995 onwards, a shift in real estate management—devolving responsibilities from the Dutch state to universities—served as a Trojan horse for financialization, triggering changes in organizational culture and a power shift from teaching and research professionals to accountants, real‐estate developers, financiers and their ilk. This case suggests that the power of finance is such that no societal domain is immune. The paper ends with a call for more non‐metropolitan case studies of financialization and argues that the only hope for salvation is a more self‐conscious defense of traditional academic values by the guardians of higher learning themselves.
L‐typeCa2+channel current characteristics are preserved in rat tail artery myocytes after one‐day storage
Authors: Mugnai P. , Durante M. , Sgaragli G. , Saponara S. , Paliuri G. , Bova S. , Fusi F.
Published: March 2014

Aim

To develop a cheap and simple method of storing for 24‐h vascular tissue and single myocytes while preserving therein the biophysical and pharmacological characteristics ofL‐typeCa2+channels and contractile activity.

Methods

Rings or vascular smooth muscle cells obtained from the rat tail main artery were used either freshly (R0h andVSMC0h) or stored for 24 h (R24h andVSMC24h) at 4 °C, to record whole‐cell L‐type Ca2+currents (ICa(L)) or measure contractile responses.

Results

R0h/VSMC0h and R24h/VSMC24h comparably contracted when stimulated with phenylephrine, highKCl orATP. In bothVSMC0h andVSMC24h,ICa(L)was identified and characterized as a stable inward current for at least 35 min;ICa(L)was comparably inhibited by the Ca2+antagonists nifedipine, verapamil and diltiazem and increased by the Ca2+channel agonist (S)‐(‐)‐Bay K 8644; current density and current–voltage relationships were similar; at more hyperpolarized holding potentials,ICa(L)intensity increased comparably; nifedipine shifted the steady‐state inactivation curve towards more negative potentials, while verapamil blockedICa(L)in a frequency‐dependent manner and slowed down the rate of recovery from inactivation in a comparable way.

Conclusion

Findings show that smooth muscle contractile activity and the biophysical and pharmacological features of L‐type Ca2+channels are similar inVSMC24h andVSMC0h. The fact that reproducible results were obtained in vascular myocytes up to 24 h after dissociation may facilitate vascular smooth muscle cell investigation by increasing throughput and reducing the number of animals required.