bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier
Authors: Zhang Zehai
Published: March 2015

Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.
Effect of bubble’s arrangement on the viscous torque in bubbly Taylor-Couette flow
Authors: Fokoua G. Ndongo , Gabillet C. , Aubert A. , Colin C.
Published: March 2015

An experimental investigation of the interactions between bubbles, coherent motion, and viscous drag in a Taylor-Couette flow with the outer cylinder at rest is presented. The cylinder radii ratio η is 0.91. Bubbles are injected inside the gap through a needle at the bottom of the apparatus. Different bubbles sizes are investigated (ratio between the bubble diameter and the gap width ranges from 0.05 to 0.125) for very small void fraction (α ≤ 0.23%). Different flow regimes are studied corresponding to Reynolds number Re based on the gap width and velocity of the inner cylinder, ranging from 6 × 102 to 2 × 104. Regarding these Re values, Taylor vortices are persistent leading to an axial periodicity of the flow. A detailed characterization of the vortices is performed for the single-phase flow. The experiment also develops bubbles tracking in a meridian plane and viscous torque of the inner cylinder measurements. The findings of this study show evidence of the link between bubbles localisation, Taylor vortices, and viscous torque modifications. We also highlight two regimes of viscous torque modification and various types of bubbles arrangements, depending on their size and on the Reynolds number. Bubbles can have a sliding and wavering motion near the inner cylinder and be either captured by the Taylor vortices or by the outflow areas near the inner cylinder. For small buoyancy effect, bubbles are trapped, leading to an increase of the viscous torque. When buoyancy induced bubbles motion is increased by comparison to the coherent motion of the liquid, a decrease in the viscous torque is rather observed. The type of bubble arrangement is parameterized by the two dimensionless parameters C and H introduced by Climent et al. [“Preferential accumulation of bubbles in Couette-Taylor flow patterns,” Phys. Fluids 19, 083301 (2007)]. Phase diagrams summarizing the various types of bubbles arrangements, viscous torque modifications, and axial wavelength evolution are built.
How Chinese residents are aware of solar photovoltaic power generation?
Authors: Shuai Jing , Shuai Chuanmin , Cheng Xin , Yao Weipei
Published: March 2015

Under the global climate change and energy crisis, solar energy has become the focus of research, development, and utilization throughout the world. Therefore, an empirical study on the awareness of residents for solar photovoltaic power generation is of great significance. Based on the 330 questionnaire data, by adopting the single factor variance analysis (S-N-K test) methodology, this paper first analyzed the differences between various groups of residents from varied perspectives of Chinese residents, i.e., different ages, different education attainments, different income levels, different genders, and different industries. Then, it conducted a regression analysis of the demographic variables by using linear regression models. The results indicate that: (1) the awareness of different types of Chinese residents is significantly different; (2) education and income levels have significant impacts on their awareness. Finally, this paper proposed corresponding policy recommendations based on these findings.
Tuning magnetic splitting of zigzag graphene nanoribbons by edge functionalization with hydroxyl groups
Authors: Zhang Huizhen , Meng Sheng , Yang Haifang , Li Lin , Fu Huixia , Ma Wei , Niu Chunyao , Sun Jiatao , Gu Changzhi
Published: March 2015

The electronic properties and relative stability of zigzag graphene nanoribbons are studied by varying the percentage of hydroxyl radicals for edge saturation using first principle calculations. The passivated structures of zigzag graphene nanoribbon have spin-polarized ground state with antiferromagnetic exchange coupling across the edge and ferromagnetic coupling along the edges. When the edges are specially passivated by hydroxyl, the potentials of spin exchange interaction across the two edges shift accordingly, resulting into a spin-semiconductor. Varying the concentration of hydroxyl groups can alter the maximum magnetization splitting. When the percentage of asymmetrically adsorbed hydroxyl reaches 50%, the magnetization splitting can reach a value as high as 275 meV due to the asymmetrical potential across the nanoribbon edges. These results would favor spintronic device applications based on zigzag graphene nanoribbons.
Acoustic logic gates and Boolean operation based on self-collimating acoustic beams
Authors: Zhang Ting , Cheng Ying , Guo Jian-zhong , Xu Jian-yi , Liu Xiao-jun
Published: March 2015

The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logic and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.
The Young's modulus of high-aspect-ratio carbon/carbon nanotube composite microcantilevers by experimental and modeling validation
Authors: Zhou Peng , Yang Xiao , He Liang , Hao Zhimeng , Luo Wen , Xiong Biao , Xu Xu , Niu Chaojiang , Yan Mengyu , Mai Liqiang
Published: March 2015

This paper reports the Young's modulus of a carbon nanotube (CNT)-reinforced carbon/CNT (C/CNT) composite microcantilevers measured by laser Doppler vibrometer and validated by finite element method. Also, the microfabrication process of the high-aspect-ratio C/CNT microcantilever arrays based on silicon micromolding and pyrolysis is presented in detail. With the in-plane natural resonant frequencies of the microcantilevers measured by a laser Doppler vibrometer, a single degree of freedom (SDoF) model based on Euler-Bernoulli (E-B) beam theory is used to calculate the Young's modulus of this composite. To figure out whether this SDoF model can be applied to these composite microcantilevers, the finite element (FE) simulation of these microcantilevers was performed. The Young's modulus of C/CNT composite microcantilevers fabricated by the pyrolysis process at 600 °C is 9391 MPa, and a good agreement between the results from experiments and FE simulation is obtained.
Terahertz magnetic and electric Mie resonances of an all-dielectric one-dimensional grating
Authors: Yang Yuping , Cui Bin , Geng Zhaoxin , Feng Shuai
Published: March 2015

High-resolution resonant phenomena in an all-dielectric one-dimensional (1D) grating are theoretically and experimentally demonstrated at terahertz frequencies. In contrast to surface plasmon resonances in the 1D metallic grating, a series of high-qualify Mie resonances were excited in the all-dielectric structure, and displayed strong frequency-selection and polarization-sensitivity behaviors. In addition, the dielectric 1D grating reveals less absorption loss, which would considerably enhance the reflectivity. The coupling effects of the high-permittivity arrayed silicon pillar, which exhibit magnetic and electric Mie resonances are calculated by use of finite element method and the theoretical simulations are in good agreement with the corresponding experimental results.
Defect-engineered GaN:Mg nanowire arrays for overall water splitting under violet light
Authors: Kibria M. G. , Chowdhury F. A. , Zhao S. , Trudeau M. L. , Guo H. , Mi Z.
Published: March 2015

We report that by engineering the intra-gap defect related energy states in GaN nanowire arrays using Mg dopants, efficient and stable overall neutral water splitting can be achieved under violet light. Overall neutral water splitting on Rh/Cr2O3 co-catalyst decorated Mg doped GaN nanowires is demonstrated with intra-gap excitation up to 450 nm. Through optimized Mg doping, the absorbed photon conversion efficiency of GaN nanowires reaches ∼43% at 375–450 nm, providing a viable approach to extend the solar absorption of oxide and non-oxide photocatalysts.
Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers
Authors: Wang G. , Palleau E. , Amand T. , Tongay S. , Marie X. , Urbaszek B.
Published: March 2015

We investigate valley exciton dynamics in MoSe2 monolayers in polarization- and time-resolved photoluminescence (PL) spectroscopy at 4 K. Following circularly polarized laser excitation, we record a low circular polarization degree of the PL of typically ≤5%. This is about 10 times lower than the polarization induced under comparable conditions in MoS2 and WSe2 monolayers. The evolution of the exciton polarization as a function of excitation laser energy and power is monitored in PL excitation experiments. Fast PL emission times are recorded for both the neutral exciton of ≤3 ps and for the charged exciton (trion) of 12 ps.
Resource use and environmental impacts from beef production in eastern Australia investigated using life cycle assessment
Authors: Wiedemann Stephen , McGahan Eugene , Murphy Caoilinn , Yan Mingjia
Published: March 2015

Resource use and environmental impacts are important factors relating to the sustainability of beef production in Australia. This study used life cycle assessment to investigate impacts from grass-finished beef production in eastern Australia to the farm gate, reporting impacts per kilogram of liveweight (LW) produced. Mean fossil fuel energy demand was found to vary from 5.6 to 8.4 MJ/kg LW, mean estimated fresh water consumption from 117.9 to 332.4 L/kg LW and crop land occupation from 0.3 to 6.4 m2/kg LW. Mean greenhouse gas emissions ranged from 10.6 to 12.4 kg CO2-e/kg LW (excluding land use and direct land-use change emissions) and were not significantly different (P > 0.05) for export or domestic market classes. Enteric methane was the largest contributor to greenhouse gas emissions, and multiple linear regression analysis revealed that weaning rate and average daily gain explained 80% of the variability in supply chain greenhouse gas emissions. Fresh water consumption was found to vary significantly among individual farms depending on climate, farm water supply efficiency and the use of irrigation. The impact of water use was measured using the stress-weighted water use indicator, and ranged from 8.4 to 104.2 L H2O-e/kg LW. The stress-weighted water use was influenced more by regional water stress than the volume of fresh water consumption. Land occupation was assessed with disaggregation of crop land, arable pasture land and non-arable land, which revealed that the majority of beef production utilised non-arable land that is unsuitable for most alternative food production systems.
Characterising sediments of a tropical sediment-starved shelf using cluster analysis of physical and geochemical variables
Authors: Radke Lynda C. , Li Jin , Douglas Grant , Przeslawski Rachel , Nichol Scott , Siwabessy Justy , Huang Zhi , Trafford Janice , Watson Tony , Whiteway Tanya
Published: March 2015

Environmental context
Australia's tropical marine estate is a biodiversity hotspot that is threatened by human activities. Analysis and interpretation of large physical and geochemistry data sets provides important information on processes occurring at the seafloor in this poorly known area. These processes help us to understand how the seafloor functions to support biodiversity in the region.

Abstract
Baseline information on habitats is required to manage Australia's northern tropical marine estate. This study aims to develop an improved understanding of seafloor environments of the Timor Sea. Clustering methods were applied to a large data set comprising physical and geochemical variables that describe organic matter (OM) reactivity, quantity and source, and geochemical processes. Arthropoda (infauna) were used to assess different groupings. Clusters based on physical and geochemical data discriminated arthropods better than geomorphic features. Major variations among clusters included grain size and a cross-shelf transition from authigenic-Mn–As enrichments (inner shelf) to authigenic-P enrichment (outer shelf). Groups comprising raised features had the highest reactive OM concentrations (e.g. low chlorin indices and C:N ratios, and high reaction rate coefficients) and benthic algal δ13C signatures. Surface area-normalised OM concentrations higher than continental shelf norms were observed in association with: (i) low δ15N, inferring Trichodesmium input; and (ii) pockmarks, which impart bottom–up controls on seabed chemistry and cause inconsistencies between bulk and pigment OM pools. Low Shannon–Wiener diversity occurred in association with low redox and porewater pH and published evidence for high energy. Highest β-diversity was observed at euphotic depths. Geochemical data and clustering methods used here provide insight into ecosystem processes that likely influence biodiversity patterns in the region.
Characterisation of oil contaminated soils by comprehensive multiphase NMR spectroscopy
Authors: Farooq Hashim , Courtier-Murias Denis , Simspon Myrna J. , Maas Werner E. , Fey Michael , Andrew Brian , Struppe Jochem , Hutchins Howard , Krishnamurthy Sridevi , Kumar Rajeev , Monette Martine , Stronks Henry J. , Simpson André J.
Published: March 2015

Environmental context
Novel technology is used to examine oil contaminated soil to better understand this longstanding problem. The data indicate that oil forms a non-discriminant layer over all the soil components, which in their natural state would be exposed to water, and that it retains certain polar compounds while contributing other oil contaminants to the surrounding porewater and groundwater. Such molecular level information helps to better understand the reoccurrence of hydrophobicity in remediated soil, and could lead to novel clean-up methods.

Abstract
Comprehensive multiphase (CMP) NMR spectroscopy is a novel NMR technology introduced in 2012. CMP NMR spectroscopy permits the analysis of solid, gel and liquid phases in unaltered natural samples. Here the technology is applied to control and oil contaminated soils to understand the molecular processes that give rise to non-wettable soils. 13C solid-state NMR spectroscopy is found to be excellent for studying the bulk rigid components of the soils whereas 1H solution and gel-state NMR provide a complimentary overview to subtleties occurring at the soil–water interface. Considered holistically the NMR data support the finding that the oil forms a non-discriminant layer over all the soil components, which in the natural state, would be exposed to water. Specifically, the oil was found to preferentially coat aliphatics and carbohydrates that normally stick out at the soil–water interface. In addition, it was shown that the oil forms a barrier that keeps small polar molecules such as formic acid inside the soil. At the soil–water interface selective oil components, such as asphaltenes, were found to exhibit unrestricted diffusion, suggesting that these components could leach into surrounding groundwater.
CFTR and sphingolipids mediate hypoxic pulmonary vasoconstriction
Authors: Tabeling Christoph , Yu Hanpo , Wang Liming , Ranke Hannes , Goldenberg Neil M. , Zabini Diana , Noe Elena , Krauszman Adrienn , Gutbier Birgitt , Yin Jun , Schaefer Michael , Arenz Christoph , Hocke Andreas C. , Suttorp Norbert , Proia Richard L. , Witzenrath Martin , Kuebler Wolfgang M.
Published: March 2015

Significance

Hypoxic pulmonary vasoconstriction (HPV) is a physiological mechanism that protects against systemic hypoxemia by redistributing blood flow from poorly to better ventilated areas of the lung, thereby minimizing ventilation-perfusion mismatch. However, in chronic hypoxemia-associated lung disease, HPV contributes to pulmonary hypertension. In this study, we provide novel evidence for a dual role of sphingolipids as important signal mediators in HPV, which critically depends on the presence of functional cystic fibrosis (CF) transmembrane conductance regulator (CFTR). CFTR gene mutations cause CF, which is associated with profound pulmonary ventilation-perfusion mismatches. The present findings propel our current understanding of HPV, establish a previously undescribed mechanism for hypoxemia in CF disease, and identify CFTR as a functional contributor to the pathologic changes in hypoxia-associated pulmonary hypertension.
Combinatorial proteomic analysis of intercellular signaling applied to the CD28 T-cell costimulatory receptor
Authors: Tian Ruijun , Wang Haopeng , Gish Gerald D. , Petsalaki Evangelia , Pasculescu Adrian , Shi Yu , Mollenauer Marianne , Bagshaw Richard D. , Yosef Nir , Hunter Tony , Gingras Anne-Claude , Weiss Arthur , Pawson Tony
Published: March 2015

Significance

Intracellular signaling during complex cell–cell interactions, such as between immune cells, provides essential cues leading to cell responses. Global characterization of these signaling events is critical for systematically exploring and understanding how they eventually control cell fate. However, proteome-wide characterization of intercellular signaling under physiologically relevant conditions involving multiple interacting receptors during cell–cell interactions remains challenging. We developed an integrated proteomic strategy for quantitatively profiling intercellular-signaling events mediated by protein phosphorylation and protein–protein interaction. We applied this approach to determine the influence of a single receptor-ligand pair during T-cell stimulation by blocking the interaction of the CD28 costimulatory receptor with its ligand. This approach is generally applicable to other transmembrane receptors involved in signaling during complex cell interactions.
The coreceptor CD4 is expressed in distinct nanoclusters and does not colocalize with T-cell receptor and active protein tyrosine kinase p56lck
Authors: Roh Kyung-Ho , Lillemeier Björn F. , Wang Feng , Davis Mark M.
Published: March 2015

Significance

Immune cell signaling is heavily associated with the spatial organization of molecules. Here, we examined the nanoscale organization of coreceptor CD4 and its relative spatial localization to the T-cell receptor and the active form of Src kinase p56lck (Lck), using two different superresolution microscopy techniques photoactivated localization microscopy and direct stochastic optical reconstruction microscopy in both living and fixed cells. With concurrent spatial analyses, we show that neither CD4/T-cell antigen receptor nor CD4/active Lck nanoclusters colocalize but only overlap at the interfaces. In activated T cells, the enhanced clustering of each kind results in increased seclusion from each other. Our observations here in molecular resolution may reveal the general roles that are played by nanoscale organization of critical components in immune cell signaling.
Rural households' decision-making in fuelwood collection. A case study of natural forest margins in the tropics
Authors: Illukpitiya Prabodh , Gopalakrishnan Chennat
Published: March 2015

Households located in peripheral villages of the natural forests are heavily dependent on fuelwood for their primary energy source. Due to excessive use, the productivity of the remaining forests is at a critical stage. The study's main objective was to assess the household decision-making behavior in fuelwood extraction from natural forests. Households' decision-making behavior was tested using social, economic and physical factors. Five forest reserves were selected for the study where fuelwood dependency is pronounced. The study findings showed factors such as off-farm income, wealth, diversification index, agricultural efficiency and male–female ratio had negative and significant effects on fuelwood dependency. Income diversification, creating off-farm employment, augmenting household wealth and farming efficiency may be viable options for minimizing fuelwood dependency.
A Cross-National Measure of Electoral Competitiveness
Authors: Kayser Mark Andreas , Lindstädt René
Published: March 2015

Electoral competitiveness is a key explanatory construct across a broad swath of phenomena, finding application in diverse areas related to political incentives and behavior. Despite its frequent theoretical use, no valid measure of electoral competitiveness exists that applies across different electoral and party systems. We argue that one particular type of electoral competitiveness'electoral risk'can be estimated across institutional contexts and matters most for incumbent behavior. We propose, estimate, and make available a cross-nationally applicable measure for elections in 22 developed democracies between 1960 and 2011. Unlike extant alternatives, our measure captures vote volatility and is constructed at the party (not system) level, exogenous to most policy predictors, and congruent with the perceptions and incentives of policy-makers.
Doppler tomography by total variation minimization
Authors: Uemura Makoto , Kato Taichi , Nogami Daisaku , Mennickent Ronald
Published: March 2015

We have developed a new model of Doppler tomography using total variation minimization (DTTVM). This method can reconstruct localized and nonaxisymmetric profiles with sharp edges in the Doppler map. This characteristic is emphasized in the case where input data are small in number. We apply this model to natural data for the dwarf nova WZ Sge in superoutburst and TU Men in quiescence. We confirm that DTTVM can reproduce the observed spectra with high precision. Compared with the models based on the maximum entropy method, our new model can provide Doppler maps that little depend on the hyperparameter and on the presence of the absorption core. We also introduce a cross-validation method of estimating reasonable values of a hyperparameter in the model from the data themselves.
Site Selection Bias in Program Evaluation
*
Authors: Allcott Hunt
Published: March 2015

“Site selection bias” can occur when the probability that a program is adopted or evaluated is correlated with its impacts. I test for site selection bias in the context of the Opower energy conservation programs, using 111 randomized control trials involving 8.6 million households across the United States. Predictions based on rich microdata from the first 10 replications substantially overstate efficacy in the next 101 sites. Several mechanisms caused this positive selection. For example, utilities in more environmentalist areas are more likely to adopt the program, and their customers are more responsive to the treatment. Also, because utilities initially target treatment at higher-usage consumer subpopulations, efficacy drops as the program is later expanded. The results illustrate how program evaluations can still give systematically biased out-of-sample predictions, even after many replications.
Impact of Hyperpolarization-activated, Cyclic Nucleotide-gated Cation Channel Type 2 for the Xenon-mediated Anesthetic Effect
Authors: Mattusch Corinna , Kratzer Stephan , Buerge Martina , Kreuzer Matthias , Engel Tatiana , Kopp Claudia , Biel Martin , Hammelmann Verena , Ying Shui-Wang , Goldstein Peter A. , Kochs Eberhard , Haseneder Rainer , Rammes Gerhard
Published: March 2015

AbstractAbstract

In thalamocortical slices, xenon evoked hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channel-dependent impairment of neuronal excitability and reduced thalamocortical signal propagation. In HCN2 knockout mice, the sedative effect of xenon was not observed. The data suggest that depression of thalamocortical signal propagation that is in part mediated by HCN2 channels might contribute to the anesthetic action of xenon.

Background:

The thalamus is thought to be crucially involved in the anesthetic state. Here, we investigated the effect of the inhaled anesthetic xenon on stimulus-evoked thalamocortical network activity and on excitability of thalamocortical neurons. Because hyperpolarization-activated, cyclic nucleotide-gated cation (HCN) channels are key regulators of neuronal excitability in the thalamus, the effect of xenon on HCN channels was examined.

Methods:

The effects of xenon on thalamocortical network activity were investigated in acutely prepared brain slices from adult wild-type and HCN2 knockout mice by means of voltage-sensitive dye imaging. The influence of xenon on single-cell excitability in brain slices was investigated using the whole-cell patch-clamp technique. Effects of xenon on HCN channels were verified in human embryonic kidney cells expressing HCN2 channels.

Results:

Xenon concentration-dependently diminished thalamocortical signal propagation. In neurons, xenon reduced HCN channel-mediated I
h current amplitude by 33.4 ± 12.2% (at −133 mV; n = 7; P = 0.041) and caused a left-shift in the voltage of half-maximum activation (V
1/2) from −98.8 ± 1.6 to −108.0 ± 4.2 mV (n = 8; P = 0.035). Similar effects were seen in human embryonic kidney cells. The impairment of HCN channel function was negligible when intracellular cyclic adenosine monophosphate level was increased. Using HCN2−/− mice, we could demonstrate that xenon did neither attenuate in vitro thalamocortical signal propagation nor did it show sedating effects in vivo.

Conclusions:

Here, we clearly showed that xenon impairs HCN2 channel function, and this impairment is dependent on intracellular cyclic adenosine monophosphate levels. We provide evidence that this effect reduces thalamocortical signal propagation and probably contributes to the hypnotic properties of xenon.
Pancreatic Enzyme Replacement Therapy and Coefficient of Fat Absorption in Children and Adolescents With Cystic Fibrosis
Authors: Woestenenk Janna W. , van der Ent Cornelis K. , Houwen Roderick H.J.
Published: March 2015

Objectives:

Pancreatic enzyme replacement therapy (PERT) is the proven therapy to substantially reduce fat malabsorption in patients with cystic fibrosis (CF). Few details of the daily practice regarding PERT and the resulting coefficient of fat absorption (CFA) are known. We therefore recorded the PERT and CFA in a large cohort of pancreatic insufficient pediatric patients with CF.

Methods:

We retrospectively studied 1719 completed 3‐day dietary food records, including the pancreatic enzyme intake registrations, and 1373 CFA assessments of 224 patients with CF, ages 0–17 years. The clinical characteristics, PERT, expressed as an intake of lipase unit (LU) per gram of fat per day and LU per kilogram per day, and the CFA were described for the group as a whole and separately for those on enteral tube feeding. Cross‐sectional relationship between the CFA and the LU per gram of fat per day and LU per kilogram per day were determined for each year of age. We also addressed the effect of the interventions done in patients with CFA outcomes <85%.

Results:

The LU per gram of fat per day was relatively stable throughout the age groups, whereas the LU per kilogram per day fell markedly with age. The median CFA in the age group 17 varied between 86% and 91%, however, with a CFA below 85% in 325 of 1373 (24%) of the measurements. No relationship was found between PERT and CFA. The patients with persistent CFA less than 85% had significant lower z scores weight for age and weight for height (P = 0.01) than those with CFA at least 85%.

Conclusions:

In this study population, no correlation between an enzyme dosage and the degree of fat malabsorption was found; however, a CFA below 85% was found in 24% of the measurements.
A Comprehensive Program to Reduce Rates of Hospital-Acquired Pressure Ulcers in a System of Community Hospitals
Authors: Englebright Jane , Westcott Ruth , McManus Kathryn , Kleja Kacie , Helm Colleen , Korwek Kimberly M. , Perlin Jonathan B.
Published: March 2015

Objectives

The prevention of hospital-acquired pressure ulcers (PrUs) has significant consequences for patient outcomes and the cost of care. Providers are challenged with evaluating available evidence and best practices, then implementing programs and motivating change in various facility environments.

Methods

In a large system of community hospitals, the Reducing Hospital Acquired–PrUs Program was developed to provide a toolkit of best practices, timely and appropriate data for focusing efforts, and continuous implementation support. Baseline data on PrU rates helped focus efforts on the most vulnerable patients and care situations. Facilities were empowered to use and adapt available resources to meet local needs and to share best practices for implementation across the system. Outcomes were measured by the rate of hospital-acquired PrUs, as gathered from patient discharge records.

Results

The rate of hospital-acquired stage III and IV PrUs decreased 66.3% between 2011 and 2013. Of the 149 participating facilities, 40 (27%) had zero hospital-acquired stage III and IV PrUs and 77 (52%) had a reduction in their PrU rate. Rates of all PrUs documented as present on admission did not change during this period. A comparison of different strategies used by the most successful facilities illustrated the necessity of facility-level flexibility and recognition of local workflows and patient demographics.

Conclusions

Driven by the combination of a repository of evidence-based tools and best practices, readily available data on PrU rates, and local flexibility with processes, the Reducing Hospital Acquired–PrUs Program represents the successful operationalization of improvement in a wide variety of facilities.
Relationship between amino acid changes in mitochondrial ATP6 and life-history variation in anguillid eels
Authors: Jacobsen Magnus W. , Pujolar José Martin , Hansen Michael M.
Published: March 2015

Mitochondrial genes are part of the oxidative phosphorylation pathway and important for energy production. Although evidence for positive selection at the mitochondrial level exists, few studies have investigated the link between amino acid changes and phenotype. Here we test the hypothesis that differences in two life-history related traits, migratory distance between spawning and foraging areas and larval phase duration, are associated with divergent selection within the mitochondrial ATP6 gene in anguillid eels. We compare amino acid changes among 18 species with the sequence of the putative ancestral species, believed to have shown short migratory distance and larval phase duration. We find positive correlations between both life-history related traits and (i) the number of amino acid changes and (ii) the strength of the combined physico-chemical and structural changes at positions previously identified as candidates for positive selection. This supports a link between genotype and phenotype driven by positive selection at ATP6.
Salivary oxytocin increases concurrently with testosterone and time away from home among returning Tsimane’ hunters
Authors: Jaeggi Adrian V. , Trumble Benjamin C. , Kaplan Hillard S. , Gurven Michael
Published: March 2015

Oxytocin, testosterone and cortisol can have opposing effects on social behaviour, yet few studies have examined their interactions. We measured changes in salivary oxytocin, testosterone and cortisol among Tsimane’ men returning home after hunting, an ancient context of male status competition, parental investment and cooperation. Contra normal diurnal rhythm, oxytocin increased relative to baseline and this increase was positively associated with duration of the hunt and change in testosterone, but not cortisol, social context, hunting outcome or physical activity. The concurrent increase in endogenous peripheral oxytocin and testosterone is unexpected given their opposing independent effects on social cognition and behaviour, and has not been observed before. We discuss the potential significance of these effects for the biology of pair-bonding, parenting and social foraging in humans and other species.
Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio
Authors: Kruyt Jan W. , van Heijst GertJan F. , Altshuler Douglas L. , Lentink David
Published: March 2015

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack andvice versaat high angle of attack.
Constitutive modelling of arteries considering fibre recruitment and three-dimensional fibre distribution
Authors: Weisbecker Hannah , Unterberger Michael J. , Holzapfel Gerhard A.
Published: March 2015

Structurally motivated material models may provide increased insights into the underlying mechanics and physics of arteries under physiological loading conditions. We propose a multiscale model for arterial tissue capturing three different scales (i) a single collagen fibre; (ii) bundle of collagen fibres; and (iii) collagen network within the tissue. The waviness of collagen fibres is introduced by a probability density function for the recruitment stretch at which the fibre starts to bear load. The three-dimensional distribution of the collagen fibres is described by an orientation distribution function using the bivariate von Mises distribution, and fitted to experimental data. The strain energy for the tissue is decomposed additively into a part related to the matrix material and a part for the collagen fibres. Volume fractions account for the matrix/fibre constituents. The proposed model only uses two parameters namely a shear modulus of the matrix material and a (stiffness) parameter related to a single collagen fibre. A fit of the multiscale model to representative experimental data obtained from the individual layers of a human thoracic aorta shows that the proposed model is able to adequately capture the nonlinear and anisotropic behaviour of the aortic layers.
Hamiltonian curl forces
Authors: Berry M. V. , Shukla Pragya
Published: March 2015

Newtonian forces depending only on position but which are non-conservative, i.e. whose curl is not zero, are termed ‘curl forces’. They are non-dissipative, but cannot be generated by a Hamiltonian of the familiar isotropic kinetic energy + scalar potential type. Nevertheless, a large class of such non-conservative forces (though not all) can be generated from Hamiltonians of a special type, in which kinetic energy is an anisotropic quadratic function of momentum. Examples include all linear curl forces, some azimuthal and radial forces, and some shear forces. Included are forces exerted on electrons in semiconductors, and on small particles by monochromatic light near an optical vortex. Curl forces imply restrictions on the geometry of periodic orbits, and non-conservation of Poincaré's integral invariant. Some fundamental questions remain, for example: how does curl dynamics generated by a Hamiltonian differ from dynamics under curl forces that are not Hamiltonian?
Sensory adaptation for timing perception
Authors: Roseboom Warrick , Linares Daniel , Nishida Shin'ya
Published: March 2015

Recent sensory experience modifies subjective timing perception. For example, when visual events repeatedly lead auditory events, such as when the sound and video tracks of a movie are out of sync, subsequent vision-leads-audio presentations are reported as more simultaneous. This phenomenon could provide insights into the fundamental problem of how timing is represented in the brain, but the underlying mechanisms are poorly understood. Here, we show that the effect of recent experience on timing perception is not just subjective; recent sensory experience also modifies relative timing discrimination. This result indicates that recent sensory history alters the encoding of relative timing in sensory areas, excluding explanations of the subjective phenomenon based only on decision-level changes. The pattern of changes in timing discrimination suggests the existence of two sensory components, similar to those previously reported for visual spatial attributes: a lateral shift in the nonlinear transducer that maps relative timing into perceptual relative timing and an increase in transducer slope around the exposed timing. The existence of these components would suggest that previous explanations of how recent experience may change the sensory encoding of timing, such as changes in sensory latencies or simple implementations of neural population codes, cannot account for the effect of sensory adaptation on timing perception.
Composition of symbiotic bacteria predicts survival in Panamanian golden frogs infected with a lethal fungus
Authors: Becker Matthew H. , Walke Jenifer B. , Cikanek Shawna , Savage Anna E. , Mattheus Nichole , Santiago Celina N. , Minbiole Kevin P. C. , Harris Reid N. , Belden Lisa K. , Gratwicke Brian
Published: March 2015

Symbiotic microbes can dramatically impact host health and fitness, and recent research in a diversity of systems suggests that different symbiont community structures may result in distinct outcomes for the host. In amphibians, some symbiotic skin bacteria produce metabolites that inhibit the growth of
Batrachochytrium dendrobatidis
(Bd), a cutaneous fungal pathogen that has caused many amphibian population declines and extinctions. Treatment with beneficial bacteria (probiotics) prevents Bd infection in some amphibian species and creates optimism for conservation of species that are highly susceptible to chytridiomycosis, the disease caused by Bd. In a laboratory experiment, we used Bd-inhibitory bacteria from Bd-tolerant Panamanian amphibians in a probiotic development trial with Panamanian golden frogs,
Atelopus zeteki
, a species currently surviving only in captive assurance colonies. Approximately 30% of infected golden frogs survived Bd exposure by either clearing infection or maintaining low Bd loads, but this was not associated with probiotic treatment. Survival was instead related to initial composition of the skin bacterial community and metabolites present on the skin. These results suggest a strong link between the structure of these symbiotic microbial communities and amphibian host health in the face of Bd exposure and also suggest a new approach for developing amphibian probiotics.
Rapidly increasing methyl mercury in endangered ivory gull (
Pagophila eburnea
) feathers over a 130 year record
Authors: Bond Alexander L. , Hobson Keith A. , Branfireun Brian A.
Published: March 2015

Mercury (Hg) is increasing in marine food webs, especially at high latitudes. The bioaccumulation and biomagnification of methyl mercury (MeHg) has serious effects on wildlife, and is most evident in apex predators. The MeHg body burden in birds is the balance of ingestion and excretion, and MeHg in feathers is an effective indicator of overall MeHg burden. Ivory gulls (
Pagophila eburnea
), which consume ice-associated prey and scavenge marine mammal carcasses, have the highest egg Hg concentrations of any Arctic bird, and the species has declined by more than 80% since the 1980s in Canada. We used feathers from museum specimens from the Canadian Arctic and western Greenland to assess whether exposure to MeHg by ivory gulls increased from 1877 to 2007. Based on constant feather stable-isotope (
δ
13
C,
δ
15
N) values, there was no significant change in ivory gulls' diet over this period, but feather MeHg concentrations increased 45× (from 0.09 to 4.11 µg g
−1
in adults). This dramatic change in the absence of a dietary shift is clear evidence of the impact of anthropogenic Hg on this high-latitude threatened species. Bioavailable Hg is expected to increase in the Arctic, raising concern for continued population declines in high-latitude species that are far from sources of environmental contaminants.
Sex differences in lizard escape decisions vary with latitude, but not sexual dimorphism
Authors: Samia Diogo S. M. , Møller Anders Pape , Blumstein Daniel T. , Stankowich Theodore , Cooper William E.
Published: March 2015

Sexual selection is a powerful evolutionary mechanism that has shaped the physiology, behaviour and morphology of the sexes to the extent that it can reduce viability while promoting traits that enhance reproductive success. Predation is one of the underlying mechanisms accounting for viability costs of sexual displays. Therefore, we should expect that individuals of the two sexes adjust their anti-predator behaviour in response to changes in predation risk. We conducted a meta-analysis of 28 studies (42 species) of sex differences in risk-taking behaviour in lizards and tested whether these differences could be explained by sexual dichromatism, by sexual size dimorphism or by latitude. Latitude was the best predictor of the interspecific heterogeneity in sex-specific behaviour. Males did not change their escape behaviour with latitude, whereas females had increasingly reduced wariness at higher latitudes. We hypothesize that this sex difference in risk-taking behaviour is linked to sex-specific environmental constraints that more strongly affect the reproductive effort of females than males. This novel latitudinal effect on sex-specific anti-predator behaviour has important implications for responses to climate change and for the relative roles of natural and sexual selection in different species.
The correct name of the type species of the genus Methanocorpusculum. Request for an Opinion
Authors: Oren Aharon , Garrity George M.
Published: March 2015

We propose that Methanocorpusculum parvum with type strain XII must remain the nomenclatural type of the genus Methanocorpusculum, in spite of the fact that the description of Methanogenium aggregans with type strain MSt, later transferred to the genus Methanocorpusculum as comb. nov. and then proposed as a heterotypic synonym of Methanocorpusculum parvum, was published before Methanocorpusculum parvum strain XII.
Dimensionality and the statistical power of multivariate genome-wide association studies
Authors: Márquez Eladio J. , Houle David
Published: March 2015

Mutations virtually always have pleiotropic effects, yet most genome-wide association studies (GWAS) analyze effects one trait at a time. In order to investigate the performance of a multivariate approach to GWAS, we simulated scenarios where variation in ad-dimensional phenotype space was caused by a known subset of SNPs. Multivariate analyses of variance were then carried out onktraits, wherekcould be less than, greater than or equal tod. Our results show that power is maximized and false discovery rate (FDR) minimized when the number of traits analyzed,k, matches the true dimensionality of the phenotype being analyzed,d. When true dimensionality is high, the power of a single univariate analysis can be an order of magnitude less than thek=dcase, even when the single trait with the largest genetic variance is chosen for analysis. When traits are added to a study in order of their independent genetic variation, the gains in power from increasingkup todare much larger than the loss in power whenkexceedsd. Simulations that explicitly model linkage disequilibrium (LD) indicate that when SNPs in disequilibrium are subjected to multivariate analysis, the magnitude of the apparent effect induced onto null SNPs by SNPs carrying a true effect weakens askapproachesd, such that the rank of P-values among a set of correlated SNPs becomes an increasingly reliable predictor of true positives. Multivariate GWAS outperform univariate ones under a wide range of conditions, and should become the standard in studies of the inheritance of complex phenotypes.
Deleterious mutation accumulation inArabidopsis thalianapollen genes: a role for a recent relaxation of selection
Authors: Harrison MC , Mallon EB , Twell D , Hammond RL
Published: March 2015

In many studies sex related genes have been found to evolve rapidly. We therefore expect plant pollen genes to evolve faster than sporophytic genes. In addition, pollen genes are expressed as haploids which can itself facilitate rapid evolution because recessive advantageous and deleterious alleles are not masked by dominant alleles. However, this mechanism is less straightforward to apply in the model plant speciesArabidopsis thaliana. For 1 million yearsA.thalianahas been self-compatible, a life history switch that has caused: a reduction in pollen competition, increased homozygosity and a dilution of masking in diploid expressed, sporophytic genes. In this study we have investigated the relative strength of selection on pollen genes compared to sporophytic genes inA. thaliana. We present two major findings: 1) before becoming self-compatible positive selection was stronger on pollen genes than sporophytic genes forA. thaliana; 2) current polymorphism data indicate selection is weaker on pollen genes compared to sporophytic genes. These results indicate that sinceA. thalianahas become self-compatible, selection on pollen genes has become more relaxed. This has led to higher polymorphism levels and a higher build-up of deleterious mutations in pollen genes compared to sporophytic genes.