bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging and characterization of conducting ferroelectric domain walls by photoemission electron microscopy
Authors: Schaab J. , Krug I. P. , Nickel F. , Gottlob D. M. , Doğanay H. , Cano A. , Hentschel M. , Yan Z. , Bourret E. , Schneider C. M. , Ramesh R. , Meier D.
Published: June 2014

High-resolution X-ray photoemission electron microscopy (X-PEEM) is a well-established method for imaging ferroelectric domain structures. Here, we expand the scope of application of X-PEEM and demonstrate its capability for imaging and investigating domain walls in ferroelectrics with high spatial resolution. Using ErMnO3 as test system, we show that ferroelectric domain walls can be visualized based on photo-induced charging effects and local variations in their electronic conductance can be mapped by analyzing the energy distribution of photoelectrons. Our results open the door for non-destructive, contact-free, and element-specific studies of the electronic and chemical structure at domain walls in ferroelectrics.
Crossed-magnetic-field experiments on stacked second generation superconducting tapes: Reduction of the demagnetization effects
Authors: Baghdadi M. , Ruiz H. S. , Coombs T. A.
Published: June 2014

The crossed-magnetic-field effect on the demagnetization factor of stacked second generation (2G) high temperature superconducting tapes is presented. The superconducting sample was initially magnetized along the c-axis by the field cooling magnetization method and after achieving the magnetic relaxation of the sample, an extensive set of experimental measurements for different amplitudes of an applied ac magnetic field parallel to the ab-plane was performed. On the one hand, a striking reduction of the demagnetization factor compared with the reported values for superconducting bulks is reported. On the other hand, the demagnetization factor increases linearly with the amplitude of the ac transverse magnetic field confirming the universal linear behavior for the magnetic susceptibility predicted by Brandt [Phys. Rev. B 54, 4246 (1996)]. The study has been also pursued at different frequencies of the ac transverse magnetic field in order to determine the influence of this parameter on the demagnetization factor measurements. We report an even lower demagnetization factor as long as the frequency of the transverse magnetic field increases. Thus, the significant reduction on the demagnetization factor that we have found by using stacked 2G-superconducting tapes, with higher mechanical strength compared with the one of superconducting bulks, makes to this configuration a highly attractive candidate for the future development of more efficient high-power density rotating machines and strong magnet applications.
Analytical estimation of emission zone mean position and width in organic light-emitting diodes from emission pattern image-source interference fringes
Authors: Epstein Ariel , Roberts Matthew , Tessler Nir , Einziger Pinchas D.
Published: June 2014

We present an analytical method for evaluating the first and second moments of the effective exciton spatial distribution in organic light-emitting diodes (OLED) from measured emission patterns. Specifically, the suggested algorithm estimates the emission zone mean position and width, respectively, from two distinct features of the pattern produced by interference between the emission sources and their images (induced by the reflective cathode): the angles in which interference extrema are observed, and the prominence of interference fringes. The relations between these parameters are derived rigorously for a general OLED structure, indicating that extrema angles are related to the mean position of the radiating excitons via Bragg's condition, and the spatial broadening is related to the attenuation of the image-source interference prominence due to an averaging effect. The method is applied successfully both on simulated emission patterns and on experimental data, exhibiting a very good agreement with the results obtained by numerical techniques. We investigate the method performance in detail, showing that it is capable of producing accurate estimations for a wide range of source-cathode separation distances, provided that the measured spectral interval is large enough; guidelines for achieving reliable evaluations are deduced from these results as well. As opposed to numerical fitting tools employed to perform similar tasks to date, our approximate method explicitly utilizes physical intuition and requires far less computational effort (no fitting is involved). Hence, applications that do not require highly resolved estimations, e.g., preliminary design and production-line verification, can benefit substantially from the analytical algorithm, when applicable. This introduces a novel set of efficient tools for OLED engineering, highly important in the view of the crucial role the exciton distribution plays in determining the device performance.
On second-order, divergence-free tensors
Authors: Navarro José
Published: June 2014

The aim of this paper is to describe the vector spaces of those second-order tensors on a pseudo-Riemannian manifold (i.e., tensors whose local expressions only involve second derivatives of the metric) that are divergence-free. The main result establishes isomorphisms between these spaces and certain spaces of tensors (at a point) that are invariant under the action of an orthogonal group. This result is valid for tensors with an arbitrary number of indices and symmetries among them and, in certain cases, it allows to explicitly compute basis, using the classical theory of invariants of the orthogonal group. In the particular case of tensors with two indices, we prove the Lovelock tensors are a basis for the vector space of second-order, divergence-free 2-tensors. This statement generalizes to arbitrary dimension a result established by Lovelock in the case of four-dimensional manifolds.
White noise of Nb-based microwave superconducting quantum interference device multiplexers with NbN coplanar resonators for readout of transition edge sensors
Authors: Kohjiro Satoshi , Hirayama Fuminori , Yamamori Hirotake , Nagasawa Shuichi , Fukuda Daiji , Hidaka Mutsuo
Published: June 2014

White noise of dissipationless microwave radio frequency superconducting quantum interference device (RF-SQUID) multiplexers has been experimentally studied to evaluate their readout performance for transition edge sensor (TES) photon counters ranging from near infrared to gamma ray. The characterization has been carried out at 4 K, first to avoid the low-frequency fluctuations present at around 0.1 K, and second, for a feasibility study of readout operation at 4 K for extended applications. To increase the resonant Q at 4 K and maintain low noise SQUID operation, multiplexer chips consisting of niobium nitride (NbN)-based coplanar-waveguide resonators and niobium (Nb)-based RF-SQUIDs have been developed. This hybrid multiplexer exhibited 1 × 104 ≤ Q ≤ 2 × 104 and the square root of spectral density of current noise referred to the SQUID input √SI = 31 pA/√Hz. The former and the latter are factor-of-five and seven improvements from our previous results on Nb-based resonators, respectively. Two-directional readout on the complex plane of the transmission component of scattering matrix S21 enables us to distinguish the flux noise from noise originating from other sources, such as the cryogenic high electron mobility transistor (HEMT) amplifier. Systematic noise measurements with various microwave readout powers PMR make it possible to distinguish the contribution of noise sources within the system as follows: (1) The achieved √SI is dominated by the Nyquist noise from a resistor at 4 K in parallel to the SQUID input coil which is present to prevent microwave leakage to the TES. (2) The next dominant source is either the HEMT-amplifier noise (for small values of PMR) or the quantization noise due to the resolution of 300-K electronics (for large values of PMR). By a decrease of these noise levels to a degree that is achievable by current technology, we predict that the microwave RF-SQUID multiplexer can exhibit √SI ≤ 5 pA/√Hz, i.e., close to √SI of state-of-the-art DC-SQUID-based multiplexers.
Cross-comparison of spacecraft-environment interaction model predictions applied to Solar Probe Plus near perihelion
Authors: Marchand R. , Miyake Y. , Usui H. , Deca J. , Lapenta G. , Matéo-Vélez J. C. , Ergun R. E. , Sturner A. , Génot V. , Hilgers A. , Markidis S.
Published: June 2014

Five spacecraft-plasma models are used to simulate the interaction of a simplified geometry Solar Probe Plus (SPP) satellite with the space environment under representative solar wind conditions near perihelion. By considering similarities and differences between results obtained with different numerical approaches under well defined conditions, the consistency and validity of our models can be assessed. The impact on model predictions of physical effects of importance in the SPP mission is also considered by comparing results obtained with and without these effects. Simulation results are presented and compared with increasing levels of complexity in the physics of interaction between solar environment and the SPP spacecraft. The comparisons focus particularly on spacecraft floating potentials, contributions to the currents collected and emitted by the spacecraft, and on the potential and density spatial profiles near the satellite. The physical effects considered include spacecraft charging, photoelectron and secondary electron emission, and the presence of a background magnetic field. Model predictions obtained with our different computational approaches are found to be in agreement within 2% when the same physical processes are taken into account and treated similarly. The comparisons thus indicate that, with the correct description of important physical effects, our simulation models should have the required skill to predict details of satellite-plasma interaction physics under relevant conditions, with a good level of confidence. Our models concur in predicting a negative floating potential Vfl∼−10V for SPP at perihelion. They also predict a “saturated emission regime” whereby most emitted photo- and secondary electron will be reflected by a potential barrier near the surface, back to the spacecraft where they will be recollected.
Tailoring structure of inclusion with strain-induced closure to reduce Poisson's ratio of composite materials
Authors: Hou Xiaonan , Hu Hong , Silberschmidt Vadim
Published: June 2014

A novel 3D continuum shell structure is introduced as inclusion for composite materials with special mechanical properties in this paper. Its geometry is based on a hollow re-entrant tetrahedron. In a composite, such an inclusion can demonstrate a closure effect induced by external compression. Its specific deformation mechanism results in a special character of deformation and affects effective (global) mechanical properties of the composite. A finite-element method is used to explore quantitatively and qualitatively the deformation mechanism of the suggested inclusion and its effect on the overall mechanical performance of the composite. In this study, geometrical features of the inclusion are used as parameters. The obtained results demonstrate that this kind of inclusion could reduce the composite's Poisson's ratio; moreover, its magnitude is adjustable by changing geometrical parameters of the inclusion. Besides, an overall hardening effect is achieved for the composite, with the magnitude of global stiffness also significantly affected by geometrical features of the inclusion. Thus, the developed inclusion actually provides a potential to develop new composites with a tunable Poisson's ratio and enhanced mechanical properties.
Experimental determination of the elastic cotunneling rate in a hybrid single-electron box
Authors: Sun Chia-Heng , Tai Po-Chen , Jiang Jheng-An , Wu Cen-Shawn , Chen Jeng-Chung , Chen Yung-Fu
Published: June 2014

We report measurements of charge configurations and charge transfer dynamics in a hybrid single-electron box composed of aluminum and copper. We used two single-electron transistors (SETs) to simultaneously read out different parts of the box, enabling us to map out stability diagrams of the box and identify various charge transfer processes in the box. We further characterized the elastic cotunneling in the box, which is an important source of error in electron turnstiles consisting of hybrid SETs, and found that the rate was as low as 1 Hz at degeneracy and compatible with theoretical estimates for electron tunneling via virtual states in the central superconducting island of the box.
Dynamic distortions and polaronic effects in the paramagnetic state of La0.8Ba0.2Mn1−xAlxO3 manganites
Authors: Narreto M. A. B. , Alagoz H. S. , Jeon J. , Chow K. H. , Jung J.
Published: June 2014

Dynamic distortions and polaronic effects have been investigated in La0.8Ba0.2Mn1–xAlxO3 doped manganites of R3¯c symmetry. We studied the transport and magnetic properties and constructed a phase diagram of this system. We also analyzed the dependence of the transport data on the doping level x. The dependence of the polaron activation energy in the paramagnetic state on x doping was calculated and compared with the available literature data. The results suggest an interplay between a magnetic polaron mediated conductivity which dominates at low x and a bipolaron mediated one which controls electric transport at higher doping. It is suggested that the magnetic polaron formation is responsible for the increased magnetoresistance at low Al doping. Investigation on the nature of the magneto-transport mechanism of such ferromagnetic manganite will be useful in understanding its potential applications at the paramagnetic state.
Band gaps and internal electric fields in semipolar short period InN/GaN superlattices
Authors: Gorczyca I. , Skrobas K. , Suski T. , Christensen N. E. , Svane A.
Published: June 2014

The electronic structures and internal electric fields of semipolar short-period mInN/nGaN superlattices (SLs) have been calculated for several compositions (m, n). Two types of SL are considered, (112¯2) and (202¯1), corresponding to growth along the wurtzite s2 and s6 directions, respectively. The results are compared to similar calculations for polar SLs (grown in the c-direction) and nonpolar SLs (grown in the a- and m-directions). The calculated band gaps for the semipolar SLs lie between those calculated for the nonpolar and polar SLs: For s2-SLs they fall slightly below the band gaps of a-plane SLs, whereas for s6-SLs they are considerably smaller.
Infrared spectroscopic ellipsometry study of sulfur-doped In0.53Ga0.47As ultra-shallow junctions
Authors: Richard D'Costa Vijay , Subramanian Sujith , Li Daosheng , Wicaksono Satrio , Fatt Yoon Soon , Soon Tok Eng , Yeo Yee-Chia
Published: June 2014

Sulfur mono-layer doped In0.53Ga0.47As films were investigated by infrared spectroscopic ellipsometry. The complex dielectric function of doped layers shows free carrier response which can be described by a single Drude oscillator. Electrical resistivities, carrier relaxation times, and active carrier depths are obtained for the shallow n-In0.53Ga0.47As films. Our results indicate that sub-10 nm sulfur-doped layers with active carrier concentration as high as 1.7 × 1019 cm−3 were achieved. Sheet resistances estimated from infrared spectroscopic ellipsometry are in good agreement with those obtained by electrical methods.
The Role and Significance of Rates Relief for Supporting Businesses in Wales
Authors: Peck Frank , Parry Simon , Mulvey Gail , Jackson Keith , Cabras Ignazio , Jackson Jacqui
Published: June 2014

This paper reports on a study which seeks to evaluate the role of small business rates relief as a means of government support for small businesses, in terms of both the financial benefit for recipient businesses and the symbolic significance of rates relief as a form of state support for the small business community in general. In doing so, the paper engages with the theoretical debate regarding the effectiveness and targeting of support to small businesses and how best to achieve this. The paper is based upon a survey of 391 small businesses receiving rates relief in Wales. The study contributes to the literature by filling a gap in our knowledge of business perception of the impact of rates relief and identifying some of the positive and negative aspects of such support mechanisms.
Antigen expression level threshold tunes the fate of CD8 T cells during primary hepatic immune responses
Authors: Tay Szun Szun , Wong Yik Chun , McDonald David M. , Wood Nicole A. W. , Roediger Ben , Sierro Frederic , Mcguffog Claire , Alexander Ian E. , Bishop G. Alex , Gamble Jennifer R. , Weninger Wolfgang , McCaughan Geoffrey W. , Bertolino Patrick , Bowen David G.
Published: June 2014

Significance

The liver possesses unique immunological properties, with the capability of inducing tolerance upon transplantation, yet is also the target of immune-mediated damage in chronic viral hepatitis. To investigate the basis of these dichotomous outcomes, we manipulated several determinants capable of influencing outcomes of hepatic–immune interactions. Our findings reveal that a threshold of antigen expression within the liver is the dominant factor determining the fate of CD8 T cells recognizing intrahepatic antigen, irrespective of their affinity for antigen or the site of initial antigen encounter, with high-level antigen expression leading to exhaustion of T cell function. To our knowledge, for the first time, this study provides a unified model explaining the divergent consequences of hepatic–immune interactions.
Nuclear receptor TLX stimulates hippocampal neurogenesis and enhances learning and memory in a transgenic mouse model
Authors: Murai Kiyohito , Qu Qiuhao , Sun GuoQiang , Ye Peng , Li Wendong , Asuelime Grace , Sun Emily , Tsai Guochuan E. , Shi Yanhong
Published: June 2014

Significance

How do we learn new things and remember and recall episodes? An important region in the brain, the hippocampus, plays a critical role in learning and memory. In this study, we show that manipulating the expression of the
TLX
gene affects neurogenesis in the hippocampus of adult mammalian brains. Our data demonstrate that the expression of TLX in neural precursors is both necessary and sufficient for adult hippocampal neurogenesis. Moreover, the neural precursor-specific overexpression of TLX makes significant contributions to learning and memory. Because impaired learning and memory occur both with aging and in neurodegenerative diseases, increasing TLX expression provides a potential strategy for improving cognitive performance in the elderly and in patients with neurologic diseases.
Structural and functional insight into TAF1–TAF7, a subcomplex of transcription factor II D
Authors: Bhattacharya Suparna , Lou Xiaohua , Hwang Peter , Rajashankar Kanagalaghatta R. , Wang Xiaoping , Gustafsson Jan-Åke , Fletterick Robert J. , Jacobson Raymond H. , Webb Paul
Published: June 2014

Significance

Transcription factor II D (TFIID) is a multiprotein complex that is essential for gene transcription. Together, TATA binding protein-associated factor 1 (TAF1), the biggest TFIID subunit, and TAF7 form an important control point for transcriptional initiation. Although current models suggest that TAF7 binds TAF1 to block its intrinsic histone acetyltransferase (HAT) activity, almost nothing is known about the molecular basis of TAF1–TAF7 (TAF1/7) interaction and TAF1 activity. Here, we report the atomic structure of the yeast TAF1/7 heterodimer and probe its function using biochemical techniques. Our structure suggests that yeast TAF1 is not a HAT and instead reveals that TAF1/7 displays the unexpected capacity to bind a specific repressive histone mark. This raises the possibility that TFIID binds repressive chromatin marks to control gene expression.
Long‐run and Short‐run Co‐movements in Energy Prices and the Prices of Agricultural Feedstocks for Biofuel
Authors: Myers Robert J. , Johnson Stanley R. , Helmar Michael , Baumes Harry
Published: June 2014

Recent expansions in biofuel production have led to concerns about an emerging “new relationship” between energy prices and the prices of agricultural feedstock for biofuel. We provide new econometric evidence on this relationship using common trend‐common cycle decompositions to estimate long‐run and short‐run co‐movement across various energy and agricultural prices. We also test for the presence of regime changes that may alter the relationship between energy and agricultural feedstock prices under certain conditions. We find that co‐movements between energy and agricultural feedstock prices tend to dissipate in the long‐run, which has important implications for biofuel and food policy.
Temporal variation in winter flounder recruitment at the southern margin of their range: is the decline due to increasing temperatures?
Authors: Able K. W. , Grothues T. M. , Morson J. M. , Coleman K. E.
Published: June 2014

The southern-most stock of winter flounder (Pseudopleuronectes americanus), a cold temperate species of the Northwest Atlantic, has not recovered from overfishing despite continued restrictive measures, and appears to be contracting northward. We regressed larval and settled juvenile abundance (after accounting for adult and larval contribution to variation, respectively) on temperature over several decades from collections in New Jersey, the United States, at the southern edge of their range to determine if increasing temperatures during the first year of life were responsible for this contraction. A significant stock–recruitment relationship at both stages was moderate, explaining 27.5% of the variance for larvae on adults and 20.6% for juveniles on larvae. There was no significant effect of average monthly temperature in explaining variance of the residuals for larvae, or of degree day on explaining the abundance of residuals for juveniles over a months-long settlement period. However, in both cases, residuals were widely distributed at cold temperatures, while they were always low at warm temperatures. Thus, years in which spring temperatures were warm (5–7oC for February, 7–9 for March, and 11–20 for May) always experienced poor recruitment. This threshold effect may result from an intersection with predators in response to temperature, and this may play a more important role than heat stress in determining recruitment success.
Jet-dominated quiescent states in black hole X-ray binaries: the case of V404 Cyg
Authors: Xie Fu-Guo , Yang Qi-Xiang , Ma Renyi
Published: June 2014

The dynamical structure and radiative properties of the quiescent state (X-ray luminosity ≲1034  erg s−1) of black hole X-ray transients (BHXTs) remain unclear, mainly because of low luminosity and poor data quantity. We demonstrate that the simultaneous multi-wavelength (including radio, optical, ultraviolet and X-ray bands) spectrum of V404 Cyg in its bright quiescent state can be well described by the radiation from the companion star and more importantly, the compact jet. Neither the outer thin disc nor the inner hot accretion flow is important in the total spectrum. Together with recent findings, i.e. the power-law X-ray spectrum and the non-variable X-ray spectral shape (or constant photon index) in contrast to the dramatic change in the X-ray luminosity, we argue the quiescent state spectrum of BHXTs is actually jet-dominated. Additional observational properties consistent with this jet model are also discussed as supporting evidence.
First measurement of σ8 using supernova magnitudes only
Authors: Castro Tiago , Quartin Miguel
Published: June 2014

A method was recently proposed which allows the conversion of the weak-lensing effects in the Type Ia supernova (SNeIa) Hubble diagram from noise into signal. Such signal is sensitive to the growth of structure in the universe, and in particular can be used as a measurement of σ8 independently from more traditional methods such as those based on the cosmic microwave background, cosmic shear or cluster abundance. We extend here that analysis to allow for intrinsic non-Gaussianities in the supernova probability distribution function, and discuss how this can be best modelled using the Bayes factor. Although it was shown that a precise measurement of σ8 requires ∼105 SNeIa, current data already allow an important proof of principle. In particular, we make use of the 706 supernovae with z ≤ 0.9 of the recent Joint Lightcurve Analysis catalogue and show that a simple treatment of intrinsic non-Gaussianities with a couple of nuisance parameters is enough for our method to yield the values $\,\sigma _8 = 0.84^{+0.28}_{-0.65}\,$ or  σ8 < 1.45  at a 2σ confidence level. This result is consistent with mock simulations and it is also in agreement with independent measurements and presents the first ever measurement of σ8 using SNeIa magnitudes alone.
First Report of Target Leaf Spot Caused by Corynespora cassiicola on Cowpea in China
Authors: Li J.-T. , Mo S.-X. , Fu H.-B.
Published: June 2014

Cowpea (Vigna unguiculata L.) is an important economic vegetable and is widely planted in China. During a survey of diseases in May 2009, a new leaf disease incited by the fungus Corynespora cassiicola was observed on cowpea growing in greenhouses in Shouguang city, Shandong Province, China. Circular lesions of different sizes were present on approximately 40% of the plants. Lesions were round with grayish brown centers surrounded by brownish concentric rings and ranged from 1 to 13 mm in diameter. Leaves with many lesions resulted in chlorosis, wilt, and defoliation. Yellow disk was observed on lesion edges of partly infected leaves. Abundant conidia and conidiophores appeared on the abaxial surface of leaves. To identify the causal pathogen, pieces of tissue from the leading border of lesions were sterilized in 75% ethanol for 1 min, rinsed in sterile water, transferred to potato dextrose agar (PDA), and then incubated at 28°C in an incubator. Colonies grew to 60 mm and were gray in color after 7 days. Conidiophores were straight and unbranched, pale or dark brown, and 63 to 211 × 4 to 8 μm. Conidia were born singly or in chains, obclavate or cylindrical, brown or olivaceous, 33 to 97 × 5 to 11 μm. Based on the above characteristics, the fungus was similar to C. cassiicola (Berk. & M.A. Curtis.) C.T. Wei (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS1 and ITS2 and deposited in GenBank (Accession No. KC894915). A BLAST search in GenBank indicated precise match for a sequence of C. cassiicola from cowpea in American Samoa (1). To satisfy Koch's postulates, 20 one-month-old seedlings of cowpea were sprayed with a spore suspension (1 × 105 spores/ml) of one isolate of C. cassiicola until runoff. Another 20 seedlings, sprayed with sterile water, served as non-inoculated controls. Plants were placed in a humidity chamber at 28°C for 12 h and then transferred to a growth chamber at 28°C. Symptoms similar to those described above appeared after 7 days on inoculated plants; however, no symptoms were observed on non-inoculated controls. C. cassiicola was re-isolated from inoculated plants. The pathogen can cause diseases on a number of plants and lead to losses. In China, this pathogen has previously been recorded on about 20 genera of plants. It also included V. sinensis (3), a close plant with V. unguiculata. However, to our knowledge, this is the first report of target leaf spot caused by C. cassiicola on cowpea (V. unguiculata) in China. Control measures may be needed to manage the disease.

References: (1) L. J. Dixon et al. Phytopathology 99:1015, 2009. (2) M. B. Ellis. CMI Mycol. Pap. No. 65, 1957. (3) F. L. Tai. Sylloge Fungorum Sinicorum. Science Press, Beijing, 1979.
Pathogenicity, Fungicide Resistance, and Genetic Variability ofPhytophthora rubiIsolates from Raspberry (Rubus idaeus) in the Western United States
Authors: Stewart Jane E. , Kroese Duncan , Tabima Javier F. , Larsen Meredith M. , Fieland Valerie J. , Press Caroline M. , Zasada Inga A. , Grünwald Niklaus J.
Published: June 2014

Root rot of raspberry (Rubus idaeus), thought to be primarily caused by Phytophthora rubi, is an economically important disease in the western United States. The objectives of this study were to determine which Phytophthora species are involved in root rot, examine the efficacy of different isolation methods (cane, root, and root/soil baiting with young raspberry plants), and determine if pathogenicity, fungicide resistance, and/or genetic variation exists among P. rubi isolates collected from raspberry fields in Washington, Oregon, and California. Of 275 samples, direct isolation from cane material resulted in a greater number of P. rubi isolates (39%), whereas root/soil baiting yielded the least (11%). Sequencing of the internal transcribed spacer region of 210 of the total 597 collected Phytophthora isolates showed that all but one isolate (identified as P. bisheria) were P. rubi. Results of the pathogenicity and fungicide resistance to mefenoxam comparing 14 total isolates from Washington, Oregon, and California showed that isolates were similarly virulent against red raspberry and the EC50frequency distributions showed no significant difference. These results, combined with amplified fragment length polymorphism results show that P. rubi isolates from Washington, Oregon, and California represent one large mixed population. This work provides novel insights into the isolation and biology of P. rubi in western U.S. raspberry production systems.
Viruses in Maize and Johnsongrass in Southern Ohio
Authors: Stewart L. R. , Teplier R. , Todd J. C. , Jones M. W. , Cassone B. J. , Wijeratne S. , Wijeratne A. , Redinbaugh M. G.
Published: June 2014

The two major U.S. maize viruses, Maize dwarf mosaic virus (MDMV) and Maize chlorotic dwarf virus (MCDV), emerged in southern Ohio and surrounding regions in the 1960s and caused significant losses. Planting resistant varieties and changing cultural practices has dramatically reduced virus impact in subsequent decades. Current information on the distribution, diversity, and impact of known and potential U.S. maize disease-causing viruses is lacking. To assess the current reservoir of viruses present at the sites of past disease emergence, we used a combination of serological testing and next-generation RNA sequencing approaches. Here, we report enzyme-linked immunosorbent assay and RNA-Seq data from samples collected over 2 years to assess the presence of viruses in cultivated maize and an important weedy reservoir, Johnsongrass (Sorghum halepense). Results revealed a persistent reservoir of MDMV and two strains of MCDV in Ohio Johnsongrass. We identified sequences of several other grass-infecting viruses and confirmed the presence of Wheat mosaic virus in Ohio maize. Together, these results provide important data for managing virus disease in field corn and sweet corn maize crops, and identifying potential future virus threats.
Race Affects Outcome Among Infants With Intestinal Failure
Authors: Squires Robert H. , Balint Jane , Horslen Simon , Wales Paul W. , Soden Jason , Duggan Christopher , Li Ruosha , Belle Steven H. ,   Pediatric Intestinal Failure Consortium
Published: June 2014

Objective:

Intestinal failure (IF) is a rare, devastating condition associated with significant morbidity and mortality. We sought to determine whether ethnic and racial differences were associated with patient survival and likelihood of receiving an intestinal transplant in a contemporary cohort of children with IF.

Methods:

This was an analysis of a multicenter cohort study with data collected from chart review conducted by the Pediatric Intestinal Failure Consortium. Entry criteria included infants ≤12 months receiving parenteral nutrition (PN) for ≥60 continuous days and studied for at least 2 years. Outcomes included death and intestinal transplantation (ITx). Race and ethnicity were recorded as they were in the medical record. For purposes of statistical comparisons and regression modeling, categories of race were consolidated into “white” and “nonwhite” children.

Results:

Of 272 subjects enrolled, 204 white and 46 nonwhite children were available for analysis. The 48‐month cumulative incidence probability of death without ITx was 0.40 for nonwhite and 0.16 for white children (P < 0.001); the cumulative incidence probability of ITx was 0.07 for nonwhite versus 0.31 for white children (P = 0.003). The associations between race and outcomes remained after accounting for low birth weight, diagnosis, and being seen at a transplant center.

Conclusions:

Race is associated with death and receiving an ITx in a large cohort of children with IF. This study highlights the need to investigate reasons for this apparent racial disparity in outcome among children with IF.
Sex ratio influences the motivational salience of facial attractiveness
Authors: Hahn Amanda C. , Fisher Claire I. , DeBruine Lisa M. , Jones Benedict C.
Published: June 2014

The sex ratio of the local population influences mating-related behaviours in many species. Recent experiments show that male-biased sex ratios increase the amount of financial resources men will invest in potential mates, suggesting that sex ratios influence allocation of mating effort in humans. To investigate this issue further, we tested for effects of cues to the sex ratio of the local population on the motivational salience of attractiveness in own-sex and opposite-sex faces. We did this using an effort-based key-press task, in which the motivational salience of facial attractiveness was assessed in samples of faces in which the ratio of male to female images was manipulated. The motivational salience of attractive opposite-sex, but not own-sex, faces was greater in the own-sex-biased (high competition for mates) than in the opposite-sex-biased (low competition for mates) condition. Moreover, this effect was not modulated by participant sex. These results present new evidence that sex ratio influences human mating-related behaviours. They also present the first evidence that the perceived sex ratio of the local population may modulate allocation of mating effort in women, as well as men.
Cardiac myoglobin deficit has evolved repeatedly in teleost fishes
Authors: Macqueen Daniel J. , Garcia de la serrana Daniel , Johnston Ian A.
Published: June 2014

Myoglobin (Mb) is the classic vertebrate oxygen-binding protein present in aerobic striated muscles. It functions principally in oxygen delivery and provides muscle with its characteristic red colour. Members of the Antarctic icefish family (Channichthyidae) are widely thought to be extraordinary for lacking cardiac
Mb
expression, a fact that has been attributed to their low metabolic rate and unusual evolutionary history. Here, we report that cardiac Mb deficit, associated with pale heart colour, has evolved repeatedly during teleost evolution. This trait affects both gill- and air-breathing species from temperate to tropical habitats across a full range of salinities. Cardiac Mb deficit results from total pseudogenization in three-spined stickleback and is associated with a massive reduction in mRNA level in two species that evidently retain functional Mb. The results suggest that near or complete absence of Mb-assisted oxygen delivery to heart muscle is a common facet of teleost biodiversity, even affecting lineages with notable oxygen demands. We suggest that Mb deficit may affect how different teleost species deal with increased tissue oxygen demands arising under climate change.
The body-size dependence of mutual interference
Authors: DeLong John P.
Published: June 2014

The parameters that drive population dynamics typically show a relationship with body size. By contrast, there is no theoretical or empirical support for a body-size dependence of mutual interference, which links foraging rates to consumer density. Here, I develop a model to predict that interference may be positively or negatively related to body size depending on how resource body size scales with consumer body size. Over a wide range of body sizes, however, the model predicts that interference will be body-size independent. This prediction was supported by a new dataset on interference and consumer body size. The stabilizing effect of intermediate interference therefore appears to be roughly constant across size, while the effect of body size on population dynamics is mediated through other parameters.
Rapid evolution of mimicry following local model extinction
Authors: Akcali Christopher K. , Pfennig David W.
Published: June 2014

Batesian mimicry evolves when individuals of a palatable species gain the selective advantage of reduced predation because they resemble a toxic species that predators avoid. Here, we evaluated whether—and in which direction—Batesian mimicry has evolved in a natural population of mimics following extirpation of their model. We specifically asked whether the precision of coral snake mimicry has evolved among kingsnakes from a region where coral snakes recently (1960) went locally extinct. We found that these kingsnakes have evolved
more precise
mimicry; by contrast, no such change occurred in a sympatric non-mimetic species or in conspecifics from a region where coral snakes remain abundant. Presumably, more precise mimicry has continued to evolve after model extirpation, because relatively few predator generations have passed, and the fitness costs incurred by predators that mistook a deadly coral snake for a kingsnake were historically much greater than those incurred by predators that mistook a kingsnake for a coral snake. Indeed, these results are consistent with prior theoretical and empirical studies, which revealed that only the most precise mimics are favoured as their model becomes increasingly rare. Thus, highly noxious models can generate an ‘evolutionary momentum’ that drives the further evolution of more precise mimicry—even after models go extinct.
Equilibrium distributions of simple biochemical reaction systems for time-scale separation in stochastic reaction networks
Authors: Mélykúti Bence , Hespanha João P. , Khammash Mustafa
Published: June 2014

Many biochemical reaction networks are inherently multiscale in time and in the counts of participating molecular species. A standard technique to treat different time scales in the stochastic kinetics framework is averaging or quasi-steady-state analysis: it is assumed that the fast dynamics reaches its equilibrium (stationary) distribution on a time scale where the slowly varying molecular counts are unlikely to have changed. We derive analytic equilibrium distributions for various simple biochemical systems, such as enzymatic reactions and gene regulation models. These can be directly inserted into simulations of the slow time-scale dynamics. They also provide insight into the stimulus–response of these systems. An important model for which we derive the analytic equilibrium distribution is the binding of dimer transcription factors (TFs) that first have to form from monomers. This gene regulation mechanism is compared to the cases of the binding of simple monomer TFs to one gene or to multiple copies of a gene, and to the cases of the cooperative binding of two or multiple TFs to a gene. The results apply equally to ligands binding to enzyme molecules.
Quantitative analyses of the plant cytoskeleton reveal underlying organizational principles
Authors: Breuer David , Ivakov Alexander , Sampathkumar Arun , Hollandt Florian , Persson Staffan , Nikoloski Zoran
Published: June 2014

The actin and microtubule (MT) cytoskeletons are vital structures for cell growth and development across all species. While individual molecular mechanisms underpinning actin and MT dynamics have been intensively studied, principles that govern the cytoskeleton organization remain largely unexplored. Here, we captured biologically relevant characteristics of the plant cytoskeleton through a network-driven imaging-based approach allowing us to quantitatively assess dynamic features of the cytoskeleton. By introducing suitable null models, we demonstrate that the plant cytoskeletal networks exhibit properties required for efficient transport, namely, short average path lengths and high robustness. We further show that these advantageous features are maintained during temporal cytoskeletal rearrangements. Interestingly, man-made transportation networks exhibit similar properties, suggesting general laws of network organization supporting diverse transport processes. The proposed network-driven analysis can be readily used to identify organizational principles of cytoskeletons in other organisms.
Computational modelling suggests good, bad and ugly roles of glycosaminoglycans in arterial wall mechanics and mechanobiology
Authors: Roccabianca S. , Bellini C. , Humphrey J. D.
Published: June 2014

The medial layer of large arteries contains aggregates of the glycosaminoglycan hyaluronan and the proteoglycan versican. It is increasingly thought that these aggregates play important mechanical and mechanobiological roles despite constituting only a small fraction of the normal arterial wall. In this paper, we offer a new hypothesis that normal aggregates of hyaluronan and versican pressurize the intralamellar spaces, and thereby put into tension the radial elastic fibres that connect the smooth muscle cells to the elastic laminae, which would facilitate mechanosensing. This hypothesis is supported by novel computational simulations using two complementary models, a mechanistically based finite-element mixture model and a phenomenologically motivated continuum hyperelastic model. That is, the simulations suggest that normal aggregates of glycosaminoglycans/proteoglycans within the arterial media may play equally important roles in supporting (i.e. a structural role) and sensing (i.e. an instructional role) mechanical loads. Additional simulations suggest further, however, that abnormal increases in these aggregates, either distributed or localized, may over-pressurize the intralamellar units. We submit that these situations could lead to compromised mechanosensing, anoikis and/or reduced structural integrity, each of which represent fundamental aspects of arterial pathologies seen, for example, in hypertension, ageing and thoracic aortic aneurysms and dissections.
Intraspecific phenotypic variation among alewife populations drives parallel phenotypic shifts in bluegill
Authors: Huss Magnus , Howeth Jennifer G. , Osterman Julia I. , Post David M.
Published: June 2014

Evolutionary diversification within consumer species may generate selection on local ecological communities, affecting prey community structure. However, the extent to which this niche construction can propagate across food webs and shape trait variation in competing species is unknown. Here, we tested whether niche construction by different life-history variants of the planktivorous fish alewife (Alosa pseudoharengus) can drive phenotypic divergence and resource use in the competing species bluegill (Lepomis macrochirus). Using a combination of common garden experiments and a comparative field study, we found that bluegill from landlocked alewife lakes grew relatively better when fed small than large zooplankton, had gill rakers better adapted for feeding on small-bodied prey and selected smaller zooplankton compared with bluegill from lakes with anadromous or no alewife. Observed shifts in bluegill foraging traits in lakes with landlocked alewife parallel those in alewife, suggesting interspecific competition leading to parallel phenotypic changes rather than to divergence (which is commonly predicted). Our findings suggest that species may be locally adapted to prey communities structured by different life-history variants of a competing dominant species.
Measuring partial fluorescence yield using filtered detectors
Authors: Boyko T. D. , Green R. J. , Moewes A. , Regier T. Z.
Published: June 2014

Typically, X-ray absorption near-edge structure measurements aim to probe the linear attenuation coefficient. These measurements are often carried out using partial fluorescence yield techniques that rely on detectors having photon energy discrimination improving the sensitivity and the signal-to-background ratio of the measured spectra. However, measuring the partial fluorescence yield in the soft X-ray regime with reasonable efficiency requires solid-state detectors, which have limitations due to the inherent dead-time while measuring. Alternatively, many of the available detectors that are not energy dispersive do not suffer from photon count rate limitations. A filter placed in front of one of these detectors will make the energy-dependent efficiency non-linear, thereby changing the responsivity of the detector. It is shown that using an array of filtered X-ray detectors is a viable method for measuring soft X-ray partial fluorescence yield spectra without dead-time. The feasibility of this technique is further demonstrated using α-Fe2O3as an example and it is shown that this detector technology could vastly improve the photon collection efficiency at synchrotrons and that these detectors will allow experiments to be completed with a much lower photon flux reducing X-ray-induced damage.
Improving the energy resolution of bent crystal X-ray spectrometers with position-sensitive detectors
Authors: Honkanen Ari-Pekka , Verbeni Roberto , Simonelli Laura , Moretti Sala Marco , Al-Zein Ali , Krisch Michael , Monaco Giulio , Huotari Simo
Published: June 2014

Wavelength-dispersive high-resolution X-ray spectrometers often employ elastically bent crystals for the wavelength analysis. In a preceding paper [Honkanenet al.(2014).J. Synchrotron Rad.21, 104–110] a theory for quantifying the internal stress of a macroscopically large spherically curved analyser crystal was presented. Here the theory is applied to compensate for the corresponding decrease of the energy resolution. The technique is demonstrated with a Johann-type spectrometer using a spherically bent Si(660) analyser in near-backscattering geometry, where an improvement in the energy resolution from 1.0 eV down to 0.5 eV at 9.7 keV incident photon energy was observed.
Aniline–phenol recognition: from solution through supramolecular synthons to cocrystals
Authors: Mukherjee Arijit , Dixit Karuna , Sarma Siddhartha P. , Desiraju Gautam R.
Published: June 2014

Aniline–phenol recognition is studied in the crystal engineering context in several 1:1 cocrystals that contain a closed cyclic hydrogen-bonded [...O—H...N—H...]2tetramer supramolecular synthon (II). Twelve cocrystals of 3,4,5- and 2,3,4-trichlorophenol with one of eight halogenated anilines have been characterized. Ten of these cocrystals contain an extended octamer synthon that is assembled with hydrogen bonding and π...π stacking that defines aLong-Range Synthon Aufbau Module(LSAM). The design strategy is, therefore, based on the construction and transferability of the LSAM, which is a dimer of tetramers. Using the LSAM concept, two short cell axes in the crystal structures can be predicted. Whilst one of them is dictated by synthonII, the other one is dominated by π...π interactions. The third cell axis can also be predicted, in some cases, by systematic tuning of the halogen bonds. The design strategy is also verified in cocrystals of non-halogenated precursors. The observation of this large synthon in so many structures points to its stability and possible existence in solution. To this end, one-dimensional1H and15N NMR studies, performed on the 3,4,5-trichlorophenol–3,5-dichloroaniline cocrystal in CDCl3, show characteristic downfield shifts that point to a π...π stacked structure and to the robustness of the hydrogen-bonded aggregates. Nuclear Overhauser effects point to hydrogen bonding between aniline and phenol molecules in the aggregates. Diffusion-ordered spectroscopy andT1inversion recovery experiments show that stacking is present in concentrated solution and lost at a certain dilution. A sequence of events is therefore established: molecules of the aniline and the phenol associateviahydrogen bonding to form tetramers, and tetramers subsequently stack to form octamers.