bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐resolution size distributions and emission fluxes of trace elements from Masaya volcano, Nicaragua
Authors: Martin R. S. , Sawyer G. M. , Day J. A. , LeBlond J. S. , Ilyinskaya E. , Oppenheimer C.
Published: July 2012

Active volcanoes are significant natural sources of trace elements to the atmosphere yet the processes of emission and the impacts of deposition into terrestrial and aquatic environments remain poorly understood. The varying contributions of volatile degassing and magma ejection (i.e., spattering, spraying, extrusion and fragmentation) to the emission of trace elements from Masaya volcano (Nicaragua) are investigated through measurement of high‐resolution trace element size distributions using cascade impactors in 2009 and 2010. The volatile elements (e.g., As, Cd, Tl, Cu, Pb, Zn) are strongly correlated across the size distribution and exist in the plume primarily as fine sulfate (0.6μm diameter) with lesser amounts transported as coarse sulfates (3.5 μm diameter) and coarse chlorides (11 μm diameter). These results suggest that trace elements released from the magma as chlorides react rapidly with H2SO4in the plume to form sulfates. In contrast, the non‐volatile elements (e.g., alkali earth and rare earth) exist primarily as particles in the 1–10μm range and show no correlation with sulfate, chloride or the volatile elements, suggesting that they are emitted primarily by magma ejection. Trace element emission fluxes from Masaya in 2010 were estimated using filter pack measurements, with emissions of Cu, Zn, As, Tl, Rb and Cd each in excess of 10 kg d−1. These emission fluxes are similar to those measured in 2000–2001 suggesting notable decadal stability in the emission of trace elements from Masaya.
A winter warm pool southwest of Hainan Island due to the orographic wind wake
Authors: Li Jiaxun , Wang Guihua , Xie Shang‐Ping , Zhang Ren , Sun Zhenyu
Published: July 2012

A winter warm pool off the southwest coast of Hainan Island is uncovered from high resolution satellite measurements and field observations. The warm pool is characterized by warm temperature relative to the surroundings. It forms in October, intensifies from November to next January, and decays in February. Our results show that the wind wake in the northeast winter monsoon due to the orographic blockage by mountains of Hainan Island plays an important role in generating the warm pool by reducing surface latent heat flux. The core temperature of the warm pool is correlated with the El Niño and Southern Oscillation.
Mind the gap: The impact of missing data on the calculation of phytoplankton phenology metrics
Authors: Cole Harriet , Henson Stephanie , Martin Adrian , Yool Andrew
Published: July 2012

Annual phytoplankton blooms are key events in marine ecosystems and interannual variability in bloom timing has important implications for carbon export and the marine food web. The degree of match or mismatch between the timing of phytoplankton and zooplankton annual cycles may impact larval survival with knock‐on effects at higher trophic levels. Interannual variability in phytoplankton bloom timing may also be used to monitor changes in the pelagic ecosystem that are either naturally or anthropogenically forced. Seasonality metrics that use satellite ocean color data have been developed to quantify the timing of phenological events which allow for objective comparisons between different regions and over long periods of time. However, satellite data sets are subject to frequent gaps due to clouds and atmospheric aerosols, or persistent data gaps in winter due to low sun angle. Here we quantify the impact of these gaps on determining the start and peak timing of phytoplankton blooms. We use the NASA Ocean Biogeochemical Model that assimilates SeaWiFS data as a gap‐free time series and derive an empirical relationship between the percentage of missing data and error in the phenology metric. Applied globally, we find that the majority of subpolar regions have typical errors of 30 days for the bloom initiation date and 15 days for the peak date. The errors introduced by intermittent data must be taken into account in phenological studies.
Snow cover and precipitation impacts on dry season streamflow in the Lower Mekong Basin
Authors: Cook B. I. , Bell A. R. , Anchukaitis K. J. , Buckley B. M.
Published: July 2012

Climate change impacts on dry season streamflow in the Mekong River are relatively understudied, despite the fact that water availability during this time is critically important for agricultural and ecological systems. Analyses of two gauging stations (Vientiane and Kratie) in the Lower Mekong Basin (LMB) show significant positive correlations between dry season (March through May, MAM) discharge and upper basin snow cover and local precipitation. Using snow cover, precipitation, and upstream discharge as predictors, we develop skillful regression models for MAM streamflow at Vientiane and Kratie, and force these models with output from a suite of general circulation model (GCM) experiments for the twentieth and twenty‐first centuries. The GCM simulations predict divergent trends in snow cover (decreasing) and precipitation (increasing) over the twenty‐first century, driving overall negligible long‐term trends in dry season streamflow. Our study demonstrates how future changes in dry season streamflow in the LMB will depend on changes in snow cover and precipitation, factors that will need to be considered when assessing the full basin response to other climatic and non‐climatic drivers.
Infrared extinction spectra of mineral dust aerosol: Single components and complex mixtures
Authors: Laskina Olga , Young Mark A. , Kleiber Paul D. , Grassian Vicki H.
Published: July 2012

Simultaneous Fourier transform infrared (FTIR) extinction spectra and aerosol size distributions have been measured for some components of mineral dust aerosol including feldspars (albite, oligoclase) and diatomaceous earth, as well as more complex authentic dust samples that include Iowa loess and Saharan sand. Spectral simulations for single‐component samples, derived from Rayleigh‐theory models for characteristic particle shapes, better reproduce the experimental spectra including the peak position and band shape compared to Mie theory. The mineralogy of the authentic dust samples was inferred using analysis of FTIR spectra. This approach allows for analysis of the mineralogy of complex multicomponent dust samples. Extinction spectra for the authentic dust samples were simulated from the derived sample mineralogy using published optical constant data for the individual mineral constituents and assuming an external mixture. Nonspherical particle shape effects were also included in the simulations and were shown to have a significant effect on the results. The results show that the position of the peak and the shape of the band of the IR characteristic features in the 800 to 1400 cm−1 spectral range are not well simulated by Mie theory. The resonance peaks are consistently shifted by more than +40 cm−1 relative to the experimental spectrum in the Mie simulation. Rayleigh model solutions for different particle shapes better predict the peak position and band shape of experimental spectra, even though the Rayleigh condition may not be strictly obeyed in these experiments.
Assessing carbon dynamics in natural and perturbed boreal aquatic systems
Authors: Ouellet Alexandre , Lalonde Karine , Plouhinec Jean‐Baptiste , Soumis Nicolas , Lucotte Marc , Gélinas Yves
Published: July 2012

Most natural freshwater lakes are net greenhouse gas (GHG) emitters. Compared to natural systems, human perturbations such as watershed wood harvesting and long‐term reservoir impoundment lead to profound alterations of biogeochemical processes involved in the aquatic cycle of carbon (C). We exploited these anthropogenic alterations to describe the C dynamics in five lakes and two reservoirs from the boreal forest through the analysis of dissolved carbon dioxide (CO2), methane (CH4), oxygen (O2), and organic carbon (DOC), as well as total nitrogen and phosphorus. Dissolved and particulate organic matter, forest soil/litter and leachates, as well as dissolved inorganic carbon were analyzed for elemental and stable isotopic compositions (atomic C:N ratios, δ13Corg, δ13Cinorg and δ15Ntot). We found links between the export of terrestrial organic matter (OM) to these systems and the dissolved CO2 and O2 concentrations in the water column, as well as CO2 fluxes to the atmosphere. All systems were GHG emitters, with greater emissions measured for systems with larger inputs of terrestrial OM. The differences in CO2 concentrations and fluxes appear controlled by bacterial activity in the water column and the sediment. Although we clearly observed differences in the aquatic C cycle between natural and perturbed systems, more work on a larger number of water bodies and encompassing all four seasons should be undertaken to better understand the controls, rates, and spatial as well as temporal variability of GHG emissions, and to make quantitatively meaningful comparisons of GHG emissions (and other key variables) from natural and perturbed systems.
Evaporative losses from a common reed‐dominated peachleaf willow and cottonwood riparian plant community
Authors: Kabenge Isa , Irmak Suat
Published: July 2012

Our study is one of the first to integrate and apply within‐canopy radiation physics parameters and scaling‐up leaf‐level stomatal resistace (rL) to canopy resistance (rc) approach to quantify hourly transpiration (TRP) rates of individual riparian plant species—common reed (Phragmites australis), peachleaf willow (Salix amygdaloides), and cottonwood (Populus deltoides)— in a mixed riparian plant community in the Platte River Basin in central Nebraska. Two experimental years (2009 and 2010) were contrasted by warmer air temperature and presence of flood water in 2010. The seasonal average rc values for common reed, peachleaf willow, and cottonwood in 2009 were 76, 70, and 107 s m−1, respectively. The corresponding rc values in the flood year (2010) were 70, 66, and 105 s m−1 for the same species, respectively. In 2009, the seasonal total TRP for common reed, peachleaf willow, and cottonwood were 483, 522, and 431 mm, respectively. Corresponding TRP values in 2010 were greater as 550, 655, and 496 mm, respectively. In 2009, TRP accounted for 64% of ETa during June–September, and the proportion varied between 41% and 69% for most of the season. In 2010, TRP accounted for 61% of ETa during June–September, and the proportion varied between 41% and 65% for most of the season. The average surface evaporation rate of the riparian zone was 0.81 mm d−1 in 2009 and 1.70 mm d−1 in 2010. Seasonal evaporation was 160 mm in 2009 and 312 mm in 2010. The study provides a basis for understanding the dynamics of transpiration for riparian vegetation in response to the environmental conditions and provides valuable water use data for more complete water balance analyses by accounting for the water use of riparian vegetation species.
In vivo phosphorylation of FtsZ2 in Arabidopsis thaliana
Authors: Gargano Daniela , Maple-Grødem Jodi , Møller Simon G.
Published: July 2012

The tubulin-like FtsZ protein initiates assembly of the bacterial and plastid division machineries. In bacteria, phosphorylation of FtsZ impairs GTPase activity, polymerization and interactions with other division proteins. Using a proteomics approach, we have shown that AtFtsZ2 is phosphorylated in vivo in Arabidopsis and that PGK1 (phosphoglycerate kinase 1) interacts with AtFtsZ2 in planta, suggesting a possible role in FtsZ phosphorylation.
Training Speech Language Pathologists of Adult Clients on the Implementation of AAC Into Everyday Practice
Authors: Crema Christopher , Moran Nicole
Published: July 2012

As speech-language pathologists enter into the workforce, it is clear that many of them are underprepared in the area of Alternative and Augmentative Communication (AAC). Many times, inexperienced clinicians will not be aware of the resources available to them for further clinical training in AAC. Researchers have investigated and documented how these clinicians prefer to learn about new technology as adults. In this article, we will identify and discuss the need for ongoing clinical training for clinicians with limited experience with AAC specific to the adult population, note ways in which inexperienced clinicians can obtain clinical training, and review literature that examines the various ways adult clinicians learn new and technological information most effectively.
University: The Supervisory Process in Speech-Language Pathology: Graduate Students’ Perspective
Authors: Taylor Kathryn , White Emily , Kaplan Rachael , O’Rourke Colleen M.
Published: July 2012

Supervision is a critical component of graduate education in communication sciences and disorders. Students spend a large amount of time with their supervisors, who guide them through clinical experiences in graduate school. Thus, students believe certain supervisor characteristics may enhance or inhibit their success as a student clinician. This study investigated the opinions of graduate students about the supervisor behaviors and attributes that create a positive supervisory experience. Twenty-three students in the graduate Communication Disorders Program at Georgia State University completed a survey regarding their thoughts and opinions on the supervisory process. The results of the study indicated that students prefer supervisors who are knowledgeable and supportive and who create a collegial atmosphere for supervisory conferences. The results further suggested that supervisors should provide timely feedback to supervisees in a written or face-to-face form. The results of this study can be used to offer advice to clinical supervisors on the types of feedback and interpersonal characteristics that can maximize the student clinician's success.
A Focus on Health Beliefs: What Culturally Competent Clinicians Need to Know
Authors: Harris Joyce L. , Fleming Valarie B. , Harris Cheryl L.
Published: July 2012

Health beliefs influence a variety of health-related behaviors and should be regarded as an important dimension of cultural variability. Such variability may explain disparities in health-care access, compliance, and treatment outcomes for persons from culturally and linguistically diverse (CLD) backgrounds. Cultural competence and client-centered service delivery require recognition of the effects of divergent health beliefs during clinical encounters. Assumptions derived from the Health Beliefs Model (HBM) can inform research to uncover communication-specific health beliefs held by persons from diverse populations. We conclude this article with a research protocol used to survey African American adults' knowledge and assumptions about communication processes and disorders.
Bilingual Spanish/English–Speaking Children's Sentence Reading Comprehension
Authors: Levey Sandra , Langdon Henriette W. , Rhein Deborah
Published: July 2012

A number of factors were examined to determine which were associated with 40 bilingual Spanish/English–speaking children's sentence reading comprehension (SRC). In our study, 40 bilingual Spanish/English–speaking children, age ranged from 8.07 to 14.96 years, completed nonword repetition, spoken language, receptive vocabulary, single word reading (SWR), and novel word discrimination tests, with all language and reading tests administered in English. Parents' occupations, the report of the language used in interaction with friends (English vs. Spanish), age, and academic grade were also considered as possible factors for SRC. Our results found that receptive vocabulary and SWR accounted for intact SRC. Findings revealed that 13 of the 40 bilingual children (32.5%) presented with SRC difficulties. However, only 2 of these 13 children were identified with reading difficulties prior to their participation in this study, suggesting that early screening is essential to prevent later literacy difficulties.
Many competing ceria (110) oxygen vacancy structures: From small to large supercells
Authors: Kullgren Jolla , Hermansson Kersti , Castleton Christopher
Published: July 2012

We present periodic “DFT+U” studies of single oxygen vacancies on the CeO2(110) surface using a number of different supercells, finding a range of different local minimum structures for the vacancy and its two accompanying Ce(III) ions. We find three different geometrical structures in combination with a variety of different Ce(III) localization patterns, several of which have not been studied before. The desired trapping of electrons was achieved in a two-stage optimization procedure. We find that the surface oxygen nearest to the vacancy either moves within the plane towards the vacancy, or rises out of the surface into either a symmetric or an unsymmetric bridge structure. Results are shown in seven slab geometry supercells, p(2 × 1), p(2 × 2), p(2 × 3), p(3 × 2), p(2 × 4), p(4 × 2), and p(3 × 3), and indicate that the choice of supercell can affect the results qualitatively and quantitatively. An unsymmetric bridge structure with one nearest and one next-nearest neighbour Ce(III) ion (a combination of localizations not previously found) is the ground state in all (but one) of the supercells studied here, and the relative stability of other structures depends strongly on supercell size. Within any one supercell the formation energies of the different vacancy structures differ by up to 0.5 eV, but the same structure can vary by up to ∼1 eV between supercells. Furthermore, finite size scaling suggests that the remaining errors (compared to still larger supercells) can also be ∼1 eV for some vacancy structures.
A multiconfigurational hybrid density-functional theory
Authors: Sharkas Kamal , Savin Andreas , Jensen Hans Jørgen Aa. , Toulouse Julien
Published: July 2012

We propose a multiconfigurational hybrid density-functional theory which rigorously combines a multiconfiguration self-consistent-field calculation with a density-functional approximation based on a linear decomposition of the electron-electron interaction. This gives a straightforward extension of the usual hybrid approximations by essentially adding a fraction λ of exact static correlation in addition to the fraction λ of exact exchange. Test calculations on the cycloaddition reactions of ozone with ethylene or acetylene and the dissociation of diatomic molecules with the Perdew-Burke-Ernzerhof and Becke-Lee-Yang-Parr density functionals show that a good value of λ is 0.25, as in the usual hybrid approximations. The results suggest that the proposed multiconfigurational hybrid approximations can improve over usual density-functional calculations for situations with strong static correlation effects.
Conceptual design of new polychromator on Thomson scattering system to measure Zeff
Authors: Lee Jongha , Oh Seungtae , Wi Hanmin , Oh Youngkook , Yamada I. , Narihara K. , Kawahata K. , Jeon Jongsu
Published: July 2012

To measure the Zeff with electron temperature (Te) and electron density (ne) profiles at the same time and the same position in the KSTAR tokamak, we design a new polychromator for Thomson scattering system that has additional function. The additional function is measuring bremsstrahlung intensity to calculate Zeff independent of Thomson signals. For this new polychromator, we design and fabricate a collimation lens set, and interference filter that has center wavelength of 523 nm and 2 nm FWHM. Finally, we change the lenses, detector diodes, and add the bremsstrahlung filter on the KSTAR edge Thomson scattering polychromator. Then this new polychromator was tested by Tungsten light and monochromator.
Replica exchanging self-guided Langevin dynamics for efficient and accurate conformational sampling
Authors: Wu Xiongwu , Hodoscek Milan , Brooks Bernard R.
Published: July 2012

This work presents a replica exchanging self-guided Langevin dynamics (RXSGLD) simulation method for efficient conformational searching and sampling. Unlike temperature-based replica exchanging simulations, which use high temperatures to accelerate conformational motion, this method uses self-guided Langevin dynamics (SGLD) to enhance conformational searching without the need to elevate temperatures. A RXSGLD simulation includes a series of SGLD simulations, with simulation conditions differing in the guiding effect and/or temperature. These simulation conditions are called stages and the base stage is one with no guiding effect. Replicas of a simulation system are simulated at the stages and are exchanged according to the replica exchanging probability derived from the SGLD partition function. Because SGLD causes less perturbation on conformational distribution than high temperatures, exchanges between SGLD stages have much higher probabilities than those between different temperatures. Therefore, RXSGLD simulations have higher conformational searching ability than temperature based replica exchange simulations. Through three example systems, we demonstrate that RXSGLD can generate target canonical ensemble distribution at the base stage and achieve accelerated conformational searching. Especially for large systems, RXSGLD has remarkable advantages in terms of replica exchange efficiency, conformational searching ability, and system size extensiveness.
Diffraction and absorption enhancement from textured back reflectors of thin film solar cells
Authors: Haug F.-J. , Naqavi A. , Ballif C.
Published: July 2012

We study light scattering and absorption in thin film solar cells, using a model system of a sinusoidally textured silver reflector and dielectric layers of ZnO and amorphous silicon. Experimental results are compared to a theoretical model based on a Rayleigh expansion. Taking into account the explicit interface profile, the expansion converges fast and can be truncated typically after three or four orders. At the same time, the use of realistic permittivity data correctly reproduces the intensity of diffracted orders as well as the coupling to guided modes and surface plasmon polariton resonances at the silver surface. The coupling phenomena behind the light trapping process can therefore be assessed in a simple, yet accurate manner.
Experimental determination of dielectric barrier discharge capacitance
Authors: Pipa A. V. , Hoder T. , Koskulics J. , Schmidt M. , Brandenburg R.
Published: July 2012

The determination of electrical parameters (such as instantaneous power, transferred charge, and gas gap voltage) in dielectric barrier discharge (DBD) reactors relies on estimates of key capacitance values. In the classic large-scale sinusoidal-voltage driven DBD, also known as silent or ozonizer discharge, capacitance values can be determined from charge-voltage (Q-V) plot, also called Lissajous figure. For miniature laboratory reactors driven by fast pulsed voltage waveforms with sub-microsecond rise time, the capacitance of the dielectric barriers cannot be evaluated from a single Q-V plot because of the limited applicability of the classical theory. Theoretical determination can be problematic due to electrode edge effects, especially in the case of asymmetrical electrodes. The lack of reliable capacitance estimates leads to a “capacitance bottleneck” that obstructs the determination of other DBD electrical parameters in fast-pulsed reactors. It is suggested to obtain capacitance of dielectric barriers from a plot of the maximal charge versus maximal voltage amplitude (Qmax − Vmax plot) in a manner analogous to the classical approach. The method is examined using measurements of current and voltage waveforms of a coaxial DBD reactor in argon at 100 mbar driven by square voltage pulses with a rise time of 20 ns and with different voltage amplitudes up to 10 kV. Additionally, the applicability of the method has been shown for the data reported in literature measured at 1 bar of nitrogen-oxygen gas mixtures and xenon.
The effect of a constraining metal tube on flux pinning induced stress in a long cylindrical superconductor
Authors: Yang Xiaobin , Tu Shan-Tung
Published: July 2012

The use of an alloy tube to impose pressure on a superconducting cylinder during magnetizing reduces pinning-induced tensile stress in high temperature superconductors has been well established. In this paper the natural contact state between the superconducting cylinder and the metal tube is modeled. An exact solution is obtained for the isotropic magnetoelastic problem with the superconductor behaving magnetically, and an expression for the contact pressure exerted on the superconductor by the metal tube is obtained. This expression explicitly gives the contribution of the ratio of Young’s modulus of the superconductor to that of the metal and the ratio of the internal to external radii of the metal tube. The stress profile in the superconductor, subjected to the restriction of metal tube, with both field cooled activation and pulse field activation is analyzed in terms of the Bean critical-state model. The results show that the metal tube can prevent radial expansion of the superconductor and can reduce the maximum tension for field-cooled and pulsed-field activations. These results are important for the selection of materials as well as the optimization of sizes of the alloy tube.
Vertical microbubble column–A photonic lab-on-chip for cultivation and online analysis of yeast cell cultures
Authors: Demming Stefanie , Peterat Gena , Llobera Andreu , Schmolke Hannah , Bruns Alexander , Kohlstedt Michael , Al-Halhouli Ala‘aldeen , Klages Claus-Peter , Krull Rainer , Büttgenbach Stephanus
Published: July 2012

This paper presents a vertically positioned microfluidic system made of poly(dimethylsiloxane) (PDMS) and glass, which can be applied as a microbubble column (μBC) for biotechnological screening in suspension. In this μBC, microbubbles are produced in a cultivation chamber through an integrated nozzle structure. Thus, homogeneous suspension of biomass is achieved in the cultivation chamber without requiring additional mixing elements. Moreover, blockage due to produced carbon dioxide by the microorganisms—a problem predominant in common, horizontally positioned microbioreactors (MBRs)—is avoided, as the gas bubbles are released by buoyancy at the upper part of the microsystem. The patterned PDMS layer is based on an optimized two-lithographic process. Since the naturally hydrophobic PDMS causes problems for the sufficient production of microbubbles, a method based on polyelectrolyte multilayers is applied in order to allow continuous hydrophilization of the already bonded PDMS-glass-system. The μBC comprises various microelements, including stabilization of temperature, control of continuous bubble formation, and two optical configurations for measurement of optical density with two different sensitivities. In addition, the simple and robust application and handling of the μBC is achieved via a custom-made modular plug-in adapter. To validate the scalability from laboratory scale to microscale, and thus to demonstrate the successful application of the μBC as a screening instrument, a batch cultivation of Saccharomyces cerevisiae is performed in the μBC and compared to shake flask cultivation. Monitoring of the biomass growth in the μBC with the integrated online analytics resulted in a specific growth rate of 0.32 h−1, which is almost identical to the one achieved in the shake flask cultivation (0.31 h−1). Therefore, the validity of the μBC as an alternative screening tool compared to other conventional laboratory scale systems in bioprocess development is proven. In addition, vertically positioned microbioreactors show high potential in comparison to conventional screening tools, since they allow for high density of integrated online analytics and therefore minimize time and cost for screening and guarantee improved control and analysis of cultivation parameters.
High-current carbon-epoxy capillary cathode
Authors: Gleizer J. Z. , Queller T. , Bliokh Yu. , Yatom S. , Vekselman V. , Krasik Ya. E. , Bernshtam V.
Published: July 2012

The results of experiments on the reproducible generation of an electron beam having a high current density of up to 300 A/cm2 and a satisfactorily uniform cross-sectional distribution of current density in a ∼200 kV, ∼450 ns vacuum diode with a carbon-epoxy capillary cathode are presented. It was found that the source of the electrons is the plasma formed as a result of flashover inside the capillaries. It is shown that the plasma formation occurs at an electric field ≤15 kV/cm and that the cathode sustains thousands of pulses without degradation in its emission properties. Time- and space-resolved visible light observation and spectroscopy analyses were used to determine the cathode plasma’s density, temperature, and expansion velocity. It was found that the density of the cathode plasma decreases rapidly in relation to the distance from the cathode. In addition, it was found that the main reason for the short-circuiting of the accelerating gap is the formation and expansion of the anode plasma. Finally, it was shown that when an external guiding magnetic field is present, the injection of the electron beam into the drift space with a current amplitude exceeding its critical value changes the radial distribution of the current density of the electron beam because the inner electrons are reflected from the virtual cathode.
Characterization of mechanical heterogeneity in amorphous solids
Authors: Peng H. L. , Li M. Z. , Sun B. A. , Wang W. H.
Published: July 2012

The structural geometry and size distribution of the local atomic rearrangements induced by external stress in amorphous solids are investigated by molecular dynamics studies. We find that the size distribution exhibits a generic power-law behavior and their structural geometry shows fractal feature. This indicates that the local atomic rearrangements in amorphous solids are self-organized during deformation. A simple theoretical model based on the interaction of the heterogeneous elastic field sources is proposed which predicts the power-law scaling and characterizes the properties of the local atomic rearrangements in amorphous solids.
Effect of the composition on physical properties of CdTe absorber layer fabricated by chemical molecular beam deposition for use in thin film solar cells
Authors: Razykov T. M. , Amin N. , Alghoul M. A. , Ergashev B. , Ferekides C. S. , Goswami Y. , Hakkulov M. K. , Kouchkarov K. M. , Sopian K. , Sulaiman M. Y. , Ullal H. S.
Published: July 2012

We developed revolutionary novel and low cost and nonvacuum chemical molecular beam deposition method for fabrication of thin film II-VI solar cells in the atmospheric pressure gas (He, Ar, H2) flow. High quality polycrystalline CdTe films with different compositions (stoichiometric and Cd/Te ≤1.0 and Cd/Te ≥ 1.0) and thickness of 2–3 μm were fabricated on ceramic (SiO2:Al2O3) substrates at temperature of 600 °C. Separate sources of Cd and Te with respective purities of 99.999% were used as precursors. The growth rate was varied in the range of 9–30 Å/s. The effect of the composition and CdCl2 treatment on the structure, intrinsic point defects, and electrical properties of CdTe films was investigated by XRD, AFM, Raman spectra, photoluminescence, and Hall methods.
Superlinear electroluminescence due to impact ionization in GaSb-based heterostructures with deep Al(As)Sb/InAsSb/Al(As)Sb quantum wells
Authors: Mikhailova M. P. , Ivanov E. V. , Danilov L. V. , Kalinina K. V. , Stoyanov N. D. , Zegrya G. G. , Yakovlev Yu. P. , Hulicius E. , Hospodková A. , Pangrác J. , Zíkova M.
Published: July 2012

We report on the observation of superlinear electroluminescence (EL) in nanoheterostructures based on GaSb with a deep narrow Al(As)Sb/InAsSb/Al(As)Sb quantum well (QW) in the active region, grown by metal organic vapor phase epitaxy. Electroluminescence spectra for different driving currents were measured at temperatures of 77 and 300 K. It is shown that such structure exhibits superlinear dependence of optical power on the drive current and its increase of 2–3 times in the current range 50–200 mA. This occurs due to impact ionization in the Al(As)Sb/InAsSb quantum well in which a large band offset at the interface ΔEC = 1.27 eV exceeds ionization threshold energy for electrons in the narrow-gap well. Calculation of the size quantization energy levels is presented, and possible cases of impact ionization, depending on the band offset ΔEC at the interface and on the quantum well width, are considered. This effect can be used to increase quantum efficiency and optical power of light emitting devices (lasers), as well as for photovoltaic elements.
Rb deposition on alkanethiolate monolayers on Au
Authors: Hibberd A. M. , Thorman R. M. , Wnuk J. D. , Bernasek S. L.
Published: July 2012

The performance of many devices utilizing alkali metal (AM) atoms is dependent upon properties of organic thin films used to line the inner walls of the glass vessel in which the system is contained. In this study, two alkanethiolate self-assembled monolayers on Au, 1-dodecanethiolate and 1-octanethiolate, are employed as model systems to investigate alkali metal atom-thin film interactions. Before and after Rb deposition, the alkanethiolate surface is analyzed with x-ray photoelectron spectroscopy (XPS), including angle-resolved XPS and XPS with an applied dc bias. Following Rb deposition, a shift of the C1s core-level to higher binding energy was observed; additionally, with continued Rb deposition, the atomic percent of Rb on the surface was found to saturate. The importance of these observations with regard to atomic magnetometers and the light induced atomic desorption effect are discussed.
On the size-consistency of the reduced-density-matrix method and the unitary invariant diagonal N-representability conditions
Authors: Nakata Maho , Anderson James S. M.
Published: July 2012

A promising variational approach for determining the ground state energy and its properties is by using the second-order reduced density matrix (2-RDM). However, the leading obstacle with this approach is the N-representability problem. By employing a subset of conditions (typically the P, Q, G, T1 and T2′ conditions) results comparable to those of CCSD(T) can be achieved. However, these conditions do not guarantee size-consistency. In this work, we show that size-consistency can be satisfied if the 2-RDM satisfies the following conditions: (i) the 2-RDM is unitary invariant diagonal N-representable; (ii) the 2-RDM corresponding to each (unspecified) subsystem is the eigenstate of the number of corresponding electrons; and (iii) the 2-RDM satisfies at least one of the P, Q, G, T1 and T2′ conditions. This is the first time that a computationally feasible (though demanding) sufficient condition for the RDM method that guarantees size-consistency in all chemical systems has been published in the literature.
Job Creation and Regional Change under New Labour: A Shift-Share Analysis
Authors: Jones Paul S
Published: July 2012

The paper examines changes in UK regional employment during the period of the New Labour administration, 1997–2010, with the Blair and Brown administrations considered separately. The paper employs a shift-share analysis of workplace employment data by industry and subregion, using annual data from the UK Labour Force Survey. The results reveal significant regional shifts, with interesting spatial dynamics in and around the capital and resilient employment growth in the provinces.
Moving around the City: Discourses on Walking and Cycling in English Urban Areas
Authors: Jones Tim , Pooley Colin G , Scheldeman Griet , Horton Dave , Tight Miles , Mullen Caroline , Jopson Ann , Whiteing Anthony
Published: July 2012

There remains only limited understanding of perceptions of travel behaviour in relation to short journeys in urban areas and, in particular, the perceived role that walking and cycling for personal travel can realistically play in contemporary society. This paper reveals discourses surrounding the practice, performance, identity, conflicts, and visions relating to walking and cycling in English cities. These were derived from a large-scale study that utilised a comprehensive mixed-method approach using both quantitative and qualitative methods. Q methodology was used as an additional tool to investigate subjectivities on walking and cycling in the city in a structured, interpretable format and it is this approach that is the focus of this paper. The paper concludes with a discussion on the implications of these discourses for policy makers interested in encouraging a shift from car use to walking and cycling for short journeys in urban areas.
Co-Constituting Neoliberalism: Faith-Based Organisations, Co-Option, and Resistance in the UK
Authors: Williams Andrew , Cloke Paul , Thomas Samuel
Published: July 2012

The increasing prominence of faith-based organisations (FBOs) in providing welfare in the UK has typically been regarded as a by-product of neoliberalism, as the gaps left by shrinking public service provision and the contracting out of service delivery have been filled by these and other Third Sector organisations. In this way, FBOs have been represented as merely being co-opted as inexpensive resource providers into the wider governmentalities of neoliberal politics. In this paper we critically question how the concept of neoliberalism has been put to work in accounts of voluntary sector cooption, and argue instead for a recognition of different manifestations of secularism and religion, and their connections to changing political—economic and social contexts. Using the illustration of one particular FBO in the UK, we trace how neoliberalism can be co-constituted through the involvement of FBOs, which can offer various pathways of resistance in and through the pursuit of alternative philosophies of care and political activism.
A systems science perspective and transdisciplinary models for food and nutrition security
Authors: Hammond Ross A. , Dubé Laurette
Published: July 2012

We argue that food and nutrition security is driven by complex underlying systems and that both research and policy in this area would benefit from a systems approach. We present a framework for such an approach, examine key underlying systems, and identify transdisciplinary modeling tools that may prove especially useful.
Factors associated with the diversification of the gut microbial communities within chimpanzees from Gombe National Park
Authors: Degnan Patrick H. , Pusey Anne E. , Lonsdorf Elizabeth V. , Goodall Jane , Wroblewski Emily E. , Wilson Michael L. , Rudicell Rebecca S. , Hahn Beatrice H. , Ochman Howard
Published: July 2012

The gastrointestinal tract harbors large and diverse populations of bacteria that vary among individuals and within individuals over time. Numerous internal and external factors can influence the contents of these microbial communities, including diet, geography, physiology, and the extent of contact among hosts. To investigate the contributions of such factors to the variation and changes in gut microbial communities, we analyzed the distal gut microbiota of individual chimpanzees from two communities in Gombe National Park, Tanzania. These samples, which were derived from 35 chimpanzees, many of whom have been monitored for multiple years, provide an unusually comprehensive longitudinal depth for individuals of known genetic relationships. Although the composition of the great-ape microbiota has been shown to codiversify with host species, indicating that host genetics and phylogeny have played a major role in its differentiation over evolutionary timescales, the geneaological relationships of individual chimpanzees did not coincide with the similarity in their gut microbial communities. However, the inhabitants from adjacent chimpanzee communities could be distinguished based on the contents of their gut microbiota. Despite the broad similarity of community members, as would be expected from shared diet or interactions, long-term immigrants to a community often harbored the most distinctive gut microbiota, suggesting that individuals retain hallmarks of their previous gut microbial communities for extended periods. This pattern was reinforced in several chimpanzees sampled over long temporal scales, in which the major constituents of the gut microbiota were maintained for nearly a decade.
Toll-like receptor 4 signaling in T cells promotes autoimmune inflammation
Authors: Reynolds Joseph M. , Martinez Gustavo J. , Chung Yeonseok , Dong Chen
Published: July 2012

Toll-like receptors (TLRs) are critical components of innate immunity and function as rapid pathogen sensors. TLR4 is expressed on CD4
+
T cells as well, the functional significance of which is unclear. In this study, we analyzed the function of TLR4 in T cells but did not find a role in promoting T helper (Th) cell polarization. Instead, TLR4 ligation enhanced both CD4
+
T-cell proliferation and survival in vitro. Using the experimental autoimmune encephalomyelitis (EAE) model, we found that the loss of TLR4 solely in CD4
+
T cells almost completely abrogated disease symptoms, mainly through blunted Th17 and, to a lesser degree, Th1 responses. Moreover,
Tlr4

−/−

γδ T cells were defective in IL-17 and IFN-γ production following EAE induction. This study supports an important role of this innate receptor in the direct regulation of T-cell activation and survival during autoimmune inflammation.
Metronidazole prevents reactivation of latentMycobacterium tuberculosisinfection in macaques
Authors: Lin Philana Ling , Dartois Veronique , Johnston Paul J. , Janssen Christopher , Via Laura , Goodwin Michael B. , Klein Edwin , Barry Clifton E. , Flynn JoAnne L.
Published: July 2012

TargetingMycobacterium tuberculosisbacilli in low-oxygen microenvironments, such as caseous granulomas, has been hypothesized to have the potential to shorten therapy for active tuberculosis (TB) and prevent reactivation of latent infection. We previously reported that upon low-doseM. tuberculosisinfection, equal proportions of cynomolgus macaques develop active disease or latent infection and that latently infected animals reactivated upon neutralization of TNF. Using this model we now show that chemoprophylaxis of latently infected cynomolgus macaques with 6 mo of isoniazid (INH) effectively prevented anti-TNF antibody-induced reactivation. Similarly, 2-mo treatment of latent animals with a combination of INH and rifampicin (RIF) was highly effective at preventing reactivation disease in this model. Metronidazole (MTZ), which has activity only against anaerobic, nonreplicating bacteria, was as effective as either of these treatments in preventing reactivation of latent infection. Because hypoxic lesions also occur during active TB, we further showed that addition of MTZ to INH/RIF effectively treated animals with active TB within 2 mo. Healing lesions were associated with distinct changes in cellular pathology, with a shift toward increasingly fibrotic and calcified lesions. Our data in the nonhuman primate model of active and latent TB supports targeting bacteria in hypoxic environments for preventing reactivation of latent infection and possibly shortening the duration of therapy in active TB.
Archaeal virus with exceptional virion architecture and the largest single-stranded DNA genome
Authors: Mochizuki Tomohiro , Krupovic Mart , Pehau-Arnaudet Gérard , Sako Yoshihiko , Forterre Patrick , Prangishvili David
Published: July 2012

Known viruses build their particles using a restricted number of redundant structural solutions. Here, we describe the
Aeropyrum
coil-shaped virus (ACV), of the hyperthermophilic archaeon
Aeropyrum pernix
, with a virion architecture not previously observed in the viral world. The nonenveloped, hollow, cylindrical virion is formed from a coiling fiber, which consists of two intertwining halves of a single circular nucleoprotein. The virus ACV is also exceptional for its genomic properties. It is the only virus with a single-stranded (ss) DNA genome among the known hyperthermophilic archaeal viruses. Moreover, the size of its circular genome, 24,893 nt, is double that of the largest known ssDNA genome, suggesting an efficient solution for keeping ssDNA intact at 90–95 °C, the optimal temperature range of
A. pernix
growth. The genome content of ACV is in line with its unique morphology and confirms that ACV is not closely related to any known virus.
Human cytomegalovirus latency alters the cellular secretome, inducing cluster of differentiation (CD)4+T-cell migration and suppression of effector function
Authors: Mason Gavin M. , Poole Emma , Sissons J. G. Patrick , Wills Mark R. , Sinclair John H.
Published: July 2012

After primary infection, human cytomegalovirus (HCMV) persists as a life-long latent infection, with host immunosuppression often resulting in clinical reactivation. During lytic infection, major changes in the expression of secreted cellular proteins (the secretome) occur that have profound effects on host–cell interactions, particularly at the level of the host immune response. In contrast, little is known about changes in the secretome that accompany latent infection, yet this is likely to be of major importance for the life-long carriage of this persistent human pathogen in the face of constant immunosurveillance. We have analyzed the secretome of cells carrying latent HCMV and have identified changes in several secreted cellular proteins known to be involved in regulation of the immune response and chemoattraction. Here, we show that a latency-associated increase in CC chemokine ligand (CCL)8 results in the recruitment of cluster of differentiation (CD)4+T cells to supernatants from latently infected CD34+cells but that these latent supernatants, also rich in immunosuppressive factors, inhibit cytokine secretion and cytotoxicity of HCMV-specific T-helper (Th)1 CD4+T cells. These results identify a strategy by which sites of latent HCMV can firstly recruit CD4+T cells and then inhibit their antiviral effector functions, thereby aiding the maintenance of latent infection in the face of the host immune response.
Hydrophobic gating of mechanosensitive channel of large conductance evidenced by single-subunit resolution
Authors: Birkner Jan Peter , Poolman Bert , Koçer Armağan
Published: July 2012

Mechanosensitive (MS) ion channels are membrane proteins that detect and respond to membrane tension in all branches of life. In bacteria, MS channels prevent cells from lysing upon sudden hypoosmotic shock by opening and releasing solutes and water. Despite the importance of MS channels and ongoing efforts to explain their functioning, the molecular mechanism of MS channel gating remains elusive and controversial. Here we report a method that allows single-subunit resolution for manipulating and monitoring “mechanosensitive channel of large conductance” from
Escherichia coli
. We gradually changed the hydrophobicity of the pore constriction in this homopentameric protein by modifying a critical pore residue one subunit at a time. Our experimental results suggest that both channel opening and closing are initiated by the transmembrane 1 helix of a single subunit and that the participation of each of the five identical subunits in the structural transitions between the closed and open states is asymmetrical. Such a minimal change in the pore environment seems ideal for a fast and energy-efficient response to changes in the membrane tension.