bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization and effect of 3‐aminopropyltriethoxysilane content on the properties of bentonite‐filled ethylene propylene diene monomer composites
Authors: Mathialagan M. , Ismail H.
Published: October 2012

The effect of silane coupling agent, 3‐aminopropyltriethoxysilane (APTES) content on the curing, tensile, swelling, and morphological properties of bentonite (Bt)‐filled ethylene‐propylene‐diene monomer (EPDM) composite was studied. The EPDM composites containing constant Bt composition of 30 phr and various APTES content (0, 1, 3, and 5 phr) were prepared using a laboratory scale two‐roll mill. The result showed that the cure time (t90) and scorch time (tS2) were shortened, whilst, the cure rate index (CRI), the maximum (MH) and minimum (ML) torque increased with increasing APTES content. The experimental results revealed that the optimum APTES content that led to the highest tensile and swelling properties was 3 phr. The presence of APTES greatly improved the dispersion of Bt in EPDM matrix and enhanced the interfacial interaction between EPDM and Bt. Morphological study through scanning electron microscopy revealed the enhanced adhesion between EPDM and Bt in the presence of 3 phr APTES. POLYM. COMPOS., 33:1993–2000, 2012. © 2012 Society of Plastics Engineers
Status of three‐neutrino oscillation parameters
Authors: Tórtola M.
Published: October 2012

Here we review the current status of global fits to neutrino oscillation data within the three‐flavour framework. In our analysis we include the most recent data from solar and atmospheric neutrino experiments as well as the latest results from the long‐baseline accelerator neutrino experiments and the recent measurements of reactor neutrino disappearance reported by Double Chooz, Daya Bay and RENO. We present updated determinations for the two neutrino mass splittings and the three mixing angles responsible for neutrino oscillations that, for the first time, have all been measured with 1σ accuracies ranging from 3 to 15%. A weak sensitivity for the CP violating phase δ is also reported from the global analysis.
The S3 flavour symmetry: Neutrino masses and mixings
Authors: González Canales F. , Mondragón A. , Mondragón M.
Published: October 2012

In this work, we discuss the neutrino masses and mixings as the realization of an S3 flavour permutational symmetry in two models, namely the Standard Model and an extension of the Standard Model with three Higgs doublets. In the S3 Standard Model, mass matrices of the same generic form are obtained for the neutrino and charged leptons when the S3 flavour symmetry is broken sequentially according to the chain S3L ⊗ S3R ⊃ S3diag ⊃ S2. In the minimal S3‐symmetric extension of the Standard Model, the S3 symmetry is left unbroken, and the concept of flavour is extended to the Higgs sector by introducing in the theory three Higgs fields which are SU(2) doublets. In both models, the mass matrices of the neutrinos and charged leptons are reparametrized in terms of their eigenvalues, and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrinos and charged leptons are obtained. In the case of the S3 Standard Model, from a χ2 fit of the theoretical expressions of the lepton mixing matrix to the values extracted from experiment, the numerical values of the neutrino mixing angles are obtained in excellent agreement with experimental data. In the S3 extension of the Standard Model, if two of the right handed neutrinos masses are degenerate, the reactor and atmospheric mixing angles are determined by the masses of the charged leptons, yielding θ23 in excellent agreement with experimental data, and θ13 different from zero but very small. If the masses of the three right handed neutrinos are assumed to be different, then it is possible to get θ13also in very good agreement with experimental data. We also show the branching ratios of some selected flavour changing neutral currents (FCNC) process as well as the contribution of the exchange of a neutral flavour changing scalar to the anomaly of the magnetic moment of the muon.
CCL11 (eotaxin‐1): A new diagnostic serum marker for prostate cancer
Authors: Agarwal Manisha , He Chang , Siddiqui Javed , Wei John T. , Macoska Jill A.
Published: October 2012

BACKGROUND

The recent recommendation of the U.S. Preventive Services Task Force against PSA‐based screening for prostate cancer was based, in part, on the lack of demonstrated diagnostic utility of serum PSA values in the low, but detectable range to successfully predict prostate cancer. Though controversial, this recommendation reinforced the critical need to develop, validate, and determine the utility of other serum and/or urine transcript and protein markers as diagnostic markers for PCa. The studies described here were intended to determine whether inflammatory cytokines might augment serum PSA as a diagnostic marker for prostate cancer.

METHODS

Multiplex ELISA assays were performed to quantify CCL1, CCL2, CCL5, CCL8, CCL11, CCL17, CXCL1, CXCL5, CXCL8, CXCL10, CXCL12, and IL‐6 protein levels in the serum of 272 men demonstrating serum PSA values of <10 ng/ml and undergoing a 12 core diagnostic needle biopsy for detection of prostate cancer. Logistic regression was used to identify the associations between specific chemokines and prostate cancer status adjusted for prostate volume, and baseline PSA.

RESULTS

Serum levels for CCL1 (I‐309) were significantly elevated among all men with enlarged prostates (P < 0.04). Serum levels for CCL11 (Eotaxin‐1) were significantly elevated among men with prostate cancer regardless of prostate size (P < 0.01). The remaining 10 cytokines examined in this study did not exhibit significant correlations with either prostate volume or cancer status.

CONCLUSIONS

Serum CCL11 values may provide a useful diagnostic tool to help distinguish between prostatic enlargement and prostate cancer among men demonstrating low, but detectable, serum PSA values. Prostate 73: 573–581, 2013. © 2012 Wiley Periodicals, Inc.
Evidence for family engagement in scientific reasoning at interactive animal exhibits
Authors: Kisiel James , Rowe Shawn , Vartabedian Melanie Ani , Kopczak Charles
Published: October 2012

While the opportunity to engage in scientific reasoning has been identified as an important aspect of informal science learning (National Research Council, 2009), most studies have examined this strand of science learning within the context of physics‒based science exhibits. Few have examined the presence of such activity in conjunction with live animal exhibits at zoos and aquariums. A video study of 41 families at four touch‒tank exhibits, where visitors can observe and interact with live marine species, revealed that families engaged in making claims, challenging claims, and confirming claims as well as other actions associated with scientific reasoning such as applying prior knowledge, making and testing predictions and hypotheses, and constructing arguments. We provide examples of scientific reasoning and examine the role of claims in promoting scientific reasoning. Implications for rethinking learning opportunities and interpretational approaches at touch tanks, as well as examination of the unique characteristics of these and similar exhibits, are discussed. © 2012 Wiley Periodicals, Inc. Sci Ed 96: 1047–1070, 2012
Commentary: How the debate about comparative effectiveness research should impact the future of clinical trials
Authors: Lauer Michael S.
Published: October 2012

Comparative effectiveness research represents the kind of research that arguably more directly affects clinical practice and policy. It includes observational studies, clinical trials, and systematic syntheses of existing literature. In this commentary, I argue for the ongoing and critical role of randomization in comparative effectiveness, noting the key differences between practical and explanatory trials. Copyright © 2012 John Wiley & Sons, Ltd.
Land and the food–fuel competition: insights from modeling
Authors: Prieler Sylvia , Fischer Günther , van Velthuizen Harrij
Published: October 2012

Ecological–economic model simulations of the world food system have been used to study the impacts of historic and future liquid transport biofuel expansion on agricultural markets and the environment. Almost half of global cropland increase between 2000 and 2008 (about 8 Mha or 0.5% of global cropland) can be attributed to biofuel expansion alone. The central ‘New Policies Scenario’ of the World Energy Outlook 2011 projects an increase of conventional crop‐based biofuel use from 60 Mtoe (2.5 EJ) in 2010 to annually 160 Mtoe (6.7 EJ) in 2035. Until 2020, the projected biofuel consumption provides no or little cumulative net greenhouse gas (GHG) savings as the time period is hardly sufficient to compensate for carbon losses due to over 10 Mha of additional land use conversion. By 2035, cumulative net GHG savings improve up to 2.8 Pg CO2 equivalent in a scenario with assumed higher agricultural productivity growth in developing countries. This scenario increases the developing region's competitive positions and avoids additional people at risk of hunger due to higher commodity prices caused by biofuel use. Available underutilized grassland and woodland may provide land resources suitable for nonfood energy crop production required for the second‐generation biofuel conversion pathways, while causing only limited impacts on food security and biodiversity. We estimate between 246 and 475 Mha of global grassland and woodland to be agronomically suitable for industrial‐scale lignocellulosic energy crop production, with achievable rain‐fed yields of at least 10 tons of dry matter per hectare, with good accessibility and relatively low ruminant livestock density.

This article is categorized under:

Bioenergy > Economics and Policy

Bioenergy > Climate and Environment
Hypergraph Independent Sets
Authors: CUTLER JONATHAN , RADCLIFFE A. J.
Published: October 2012

The study of extremal problems related to independent sets in hypergraphs is a problem that has generated much interest. There are a variety of types of independent sets in hypergraphs depending on the number of vertices from an independent set allowed in an edge. We say that a subset of vertices isj-independentif its intersection with any edge has size strictly less thanj. The Kruskal–Katona theorem implies that in anr-uniform hypergraph with a fixed size and order, the hypergraph with the mostr-independent sets is the lexicographic hypergraph. In this paper, we use a hypergraph regularity lemma, along with a technique developed by Loh, Pikhurko and Sudakov, to give an asymptotically best possible upper bound on the number ofj-independent sets in anr-uniform hypergraph.
Economic value of mitigation of plant invaders in a subsistence economy: incorporating labour as a mode of payment
Authors: Rai Rajesh Kumar , Scarborough Helen
Published: October 2012

This paper presents the analysis of a choice experiment designed to estimate willingness-to-pay (WTP) to mitigate damages caused by invasive plant species in a rural community of Nepal. In order to address the cash constraints problem in a subsistence economy, two payment attributes, labour contribution and membership fee, were included in the choice sets. The results reveal that rural farmers have significant WTP for forest management activities, in terms of both cash and labour contributions. The results also suggest that rural farmers value their time in this context at a different rate from the current wage rate.
Prematurity and programming: contribution of neonatal Intensive Care Unit interventions
Authors: Kalhan S. C. , Wilson-Costello D.
Published: October 2012

Contemporary clinical practice for the care of the prematurely born babies has markedly improved their rates of survival so that most of these babies are expected to grow up to live a healthy functional life. Since the clinical follow-up is of short duration (years), only limited data are available to relate non-communicable diseases in adult life to events and interventions in the neonatal period. The major events that could have a programming effect include: (1) intrauterine growth restriction; (2) interruption of pregnancy with change in redox and reactive oxygen species (ROS) injury; (3) nutritional and pharmacological protocols for clinical care; and (4) nutritional care in the first 2 years resulting in accelerated weight gain. The available data are discussed in the context of perturbations in one carbon (methyl transfer) metabolism and its possible programming effects. Although direct evidence for genomic methylation is not available, clinical and experimental data on impact of redox and ROS, of low protein intake, excess methionine load and vitamin A, on methyl transfers are reviewed. The consequences of antenatal and postnatal administration of glucocorticoids are presented. Analysis of the correlates of insulin sensitivity at older age, suggests that premature birth is the major contributor, and is compounded by gain in weight during infancy. We speculate that premature interruption of pregnancy and neonatal interventions by affecting one carbon metabolism may cause programming effects on the immature baby. These can be additive to the effects of intrauterine environment (growth restriction) and are compounded by accelerated growth in early infancy.
If substorm onset triggers tail reconnection, what triggers substorm onset?
Authors: Liu W. W. , Liang J. , Donovan E. F. , Spanswick E.
Published: October 2012

Despite the claim that tail reconnection triggers substorm onset, there is an abundance of cases wherein substorm onset triggers tail reconnection. In such cases, the first observable precursor to onset is a periodic rippling (beads) along an equatorward auroral arc. In this study, through an example, we show that substorms arising out of arcs of this type have the classical “inside‐out” evolution, including the triggering of tail reconnection as a possible result. We then investigate what the magnetospheric mode underlying the ripples along the arcs might be. The classical MHD ballooning invoked by some substorm theories is inconsistent with the observation, which exhibits a finite azimuthal wavelength comparable to the local ion gyroradius and the propensity of onset to occur under moderately high (1–10) rather than extremely high plasmaβ. We show that the onset is due to a modified ballooning mode, subject to corrections by the General Ohm's Law and ion heat flux. The net result is that the necessary condition for the instability remains unchanged from the classical MHD, but the growth rate of the instability is heavily attenuated or quenched in the high β and short azimuthal wavelength limits. In the actual magnetosphere, the mode has a wavelength ∼1,500 km, growth timescale ∼10 s, and critical plasma beta in the 3–13 range, all consistent with observations.
Upscaling of CO2 fluxes from heterogeneous tundra plant communities in Arctic Alaska
Authors: Kade Anja , Bret‐Harte M. Syndonia , Euskirchen Eugénie S. , Edgar Colin , Fulweber Randy A.
Published: October 2012

We characterized the tundra vegetation at three eddy covariance towers located along a toposequence in northern Alaska and studied seasonal variations in plot‐level CO2 fluxes among the dominant vegetation types with chambers during the summer and with the gradient‐diffusion technique during the winter. We performed footprint analyses to determine the source areas contributing to the tower fluxes and scaled plot‐level to eddy‐covariance CO2 data based on the proportion of vegetation types occurring within the footprints. At peak growing season, both gross ecosystem exchange and ecosystem respiration were greater in moist acidic tussock tundra and wet sedge tundra than in dry heath tundra. This resulted in relatively similar values of net ecosystem exchange as measured by chambers in July in tussock tundra across all topographic positions and wet sedge tundra (−2.4 to −4.2 μmol CO2/m2/s) but low values in dry heath tundra (−0.4 μmol CO2/m2/s). Winter respiration was highest for tussock tundra in December, but there were no significant differences among vegetation types in February and April. Net and gross ecosystem exchange scaled up from summer chamber measurements compared well to tower data (r2 = 0.84 and r2 = 0.78, respectively), especially on level terrain, whereas plot‐level CO2‐flux measurements in the winter did not agree well with tower data. This is one of few studies to compare plot‐level and tower fluxes during both summer and winter and to demonstrate successful upscaling of carbon exchange in Arctic tundra systems under certain conditions.
Towards a microscopic description of the free-energy landscape of water
Authors: Prada-Gracia Diego , Shevchuk Roman , Hamm Peter , Rao Francesco
Published: October 2012

Free-energy landscape theory is often used to describe complex molecular systems. Here, a microscopic description of water structure and dynamics based on configuration-space-networks and molecular dynamics simulations of the TIP4P/2005 model is applied to investigate the free-energy landscape of water. The latter is built on top of a large set of water microstates describing the kinetic stability of local hydrogen-bond arrangements up to the second solvation shell. In temperature space, the landscape displays three different regimes. At around ambient conditions, the free-energy surface is characterized by many short-lived basins of attraction which are structurally well-defined (inhomogeneous regime). At lower temperatures instead, the liquid rapidly becomes homogeneous. In this regime, the free energy is funneled-like, with fully coordinated water arrangements at the bottom of the funnel. Finally, a third regime develops below the temperature of maximal compressibility (Widom line) where the funnel becomes steeper with few interconversions between microstates other than the fully coordinated ones. Our results present a way to manage the complexity of water structure and dynamics, connecting microscopic properties to its ensemble behavior.
A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies
Authors: Szlachetko J. , Nachtegaal M. , de Boni E. , Willimann M. , Safonova O. , Sa J. , Smolentsev G. , Szlachetko M. , van Bokhoven J. A. , Dousse J.-Cl. , Hoszowska J. , Kayser Y. , Jagodzinski P. , Bergamaschi A. , Schmitt B. , David C. , Lücke A.
Published: October 2012

We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV–9600 eV. The use of a segmented crystal results in a simple and straightforward crystal preparation that allows to preserve the spectrometer resolution and spectrometer efficiency. Application of the spectrometer for time-resolved resonant inelastic x-ray scattering and single-shot x-ray emission spectroscopy is demonstrated.
Diffusion and interactions of carbon dioxide and oxygen in the vicinity of the active site of Rubisco: Molecular dynamics and quantum chemical studies
Authors: El-Hendawy Morad M. , Garate José-Antonio , English Niall J. , O’Reilly Stephen , Mooney Damian A.
Published: October 2012

Molecular dynamics (MD) at the molecular mechanical level and geometry optimisation at the quantum mechanical level have been performed to investigate the transport and fixation of oxygen and carbon dioxide in the cavity of ribulose-1,5-bisphosphate carboxylase/oxygenase, or Rubisco. Multiple MD simulations have been carried out to study the diffusive behaviour of O2 and CO2 molecules from the Mg2+ cation in Rubisco at 298 K and 1 bar, being one step in the overall process of carboxylation/oxygenation in Rubisco. In addition to this work, in order to gain additional perspective on the role of chemical reaction rates and thermodynamics, oxygen, and carbon dioxide uptake mechanisms have also been investigated by the aid of quantum chemical calculations. The results indicate that the activation barrier for carboxylation is slightly lower than that of oxygenation. This agrees qualitatively with experimental findings, and rationalises the observed competition between both catalytic processes in nature. Finally, the longer-lived persistence of CO2 in the vicinity of the active centre (i.e., slower self-diffusion) may serve to explain, in part, why carboxylation is the more kinetically favoured on an overall basis compared to oxygenation.
Resonant frequency analysis of Timoshenko nanowires with surface stress for different boundary conditions
Authors: He Qilu , Lilley Carmen M.
Published: October 2012

The influence of both surface and shear effects on the resonant frequency of nanowires (NWs) was studied by incorporating the Young-Laplace equation with the Timoshenko beam theory. Face-centered-cubic metal NWs were studied. A dimensional analysis of the resonant frequencies for fixed-fixed gold (100) NWs were compared to molecular dynamic simulations. Silver NWs with diameters from 10 nm–500 nm were modeled as a cantilever, simply supported and fixed-fixed system for aspect ratios from 2.5–20 to identify the shear, surface, and size effects on the resonant frequencies. The shear effect was found to have a larger significance than surface effects when the aspect ratios were small (i.e., <5) regardless of size for the diameters modeled. Finally, as the aspect ratio grows, the surface effect becomes significant for the smaller diameter NWs.
Modified Faraday rotation in a three-dimensional magnetophotonic opal crystal consisting of maghemite/silica composite spheres
Authors: Murai Shunsuke , Yao Situ , Nakamura Tadashi , Kawamoto Takahiro , Fujita Koji , Yano Kazuhisa , Tanaka Katsuhisa
Published: October 2012

We have prepared a three-dimensional magnetophotonic crystal and observed modulated Faraday rotation around its photonic band gap. The magnetophotonic crystal was prepared by the self-assembly of highly monodispersed silica spheres, which were heavily impregnated with maghemite (γ−Fe2O3) nanoparticles. The slab sample with a thickness of 10 μm shows a clear photonic band gap centered at λ=620 nm in optical transmittance. Faraday rotation is notably modified inside the photonic band gap.
Electrical and luminescent properties and deep traps spectra in GaN nanopillar layers prepared by dry etching
Authors: Polyakov A. Y. , Jeon Dae-Woo , Smirnov N. B. , Govorkov A. V. , Kozhukhova E. A. , Yakimov E. B. , Lee In-Hwan
Published: October 2012

Electrical properties, microcathodoluminescence spectra, and spectra of deep traps were studied for nanopillar structures prepared by dry etching of undoped GaN films using natural masks formed by Ni nanoparticles. It is shown that as-prepared nanopillar structures have low bandedge intensity, very high leakage current of Schottky diodes, their electrical properties are determined by 0.2 eV electron traps or, after etching in aqua regia, 0.14 eV electron traps that are commonly associated with radiation defects. Deep levels transient spectroscopy spectra measured after aqua regia etching are dominated by 1 eV electron traps, other common radiation defects. Annealing at 600 °C is instrumental in eliminating the 0.2 eV and 0.14 eV electron traps, but not the 1 eV traps. A higher temperature annealing at 900 °C is required for strongly suppressing the latter and increasing the bandedge luminescence peak magnitude by 2 times compared to control sample. The best results in terms of luminescence efficiency increase are produced by additional etching in aqueous solution of KOH, but subsequent etching in aqua regia is necessary to suppress excessive surface leakage due to surface contamination by the KOH treatment.
Germanium nano-cluster films as humidity and hydrogen sensors
Authors: Mackenzie D. M. A. , Brown S. A.
Published: October 2012

Films of germanium nano-clusters of 30 nm diameter were fabricated in a high-vacuum deposition apparatus utilizing an inert-gas-aggregation source. The germanium films readily formed an oxide layer in high vacuum along with a corresponding resistance increase, a process that accelerated when films were exposed to dry air. A decrease in resistance was observed when films were exposed to ambient air, and this was attributed to water vapour adsorbing on the surface. The effects of film-thickness were investigated. A reversible change in resistance of 2 orders of magnitude was observed for 99% humidity, with a response time of tens of minutes. It is proposed that the resistance-decrease occurs because water vapour creates surface defects which act as donors causing the electron concentration in the n-type film to increase. The films were also sensitive to hydrogen concentrations above 1% in dry air, with up to a factor of 25 decrease in resistance observed for 5% hydrogen concentration at room temperature. Unexpectedly, the sensitivity to hydrogen was only observed at temperatures below 100 °C, suggesting that surface moisture is necessary for films to show sensitivity to hydrogen.
Note: Comparison of grazing incidence small angle x-ray scattering of a titania sponge structure at the beamlines BW4 (DORIS III) and P03 (PETRA III)
Authors: Rawolle M. , Körstgens V. , Ruderer M. A. , Metwalli E. , Guo S. , Herzog G. , Benecke G. , Schwartzkopf M. , Buffet A. , Perlich J. , Roth S. V. , Müller-Buschbaum P.
Published: October 2012

Grazing incidence small angle x-ray scattering (GISAXS) is a powerful technique for morphology investigation of nanostructured thin films. GISAXS measurements at the newly installed P03 beamline at the storage ring PETRA III in Hamburg, Germany, are compared to the GISAXS data from the beamline BW4 at the storage ring DORIS III, which had been used extensively for GISAXS investigations in the past. As an example, a titania thin film sponge structure is investigated. Compared to BW4, at beamline P03 the resolution of larger structures is slightly improved and a higher incident flux leads to a factor of 750 in scattered intensity. Therefore, the acquisition time in GISAXS geometry is reduced significantly at beamline P03.
Surface plasmon polariton enhanced electroluminescence and electron emission from electroformed Al-Al2O3-Ag diodes
Authors: Hickmott T. W.
Published: October 2012

Electroforming of Al-Al2O3-Ag diodes results in voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) curves. Electroluminescence (EL) and electron emission into vacuum (EM) develop simultaneously. The temperature dependence between 200 and 300 K of VCNR, EL, and EM of Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 and 41 nm has been studied. I-V curves and VCNR are slightly temperature dependent. The voltage for the onset of EL, VEL, is between ∼1.3 and ∼1.9 V for the range of Al2O3 thicknesses, with small temperature dependence. The density of defects in anodic Al2O3 is >1.5 × 1020 cm−3. Defect conduction bands that form from excited states of F- or F+-centers, oxygen vacancies in Al2O3, determine the value of the barrier height at the Al-Al2O3 interface, ϕA, and they control EM. EM is anomalous. The threshold voltage for EM, VEM, is ∼1.9 to ∼2.5 V for the range of Al2O3 thicknesses, which is less than the work function of Ag, 4.6 eV. EM at 300 K is ∼10−9 A. As temperature is lowered, EM drops to ∼10−12 A at TD ≅ 290 K and recovers to ∼10−9 A at TR ≅ 260 K. The particular values of TD and TR depend on sample preparation and Al2O3 thickness. The source of anomalous EM is electrons that tunnel through the high field region at the Al-Al2O3 interface into defect conduction bands. They gain energy and momentum by combining with surface plasmon polaritons (SPPs) that are generated at the Al2O3-Ag interface by EL photons. EL from Al-Al2O3-Ag diodes with 12 nm or 15 nm of Al2O3 is much larger than EL from diodes with thicker Al2O3 layers. The conducting channel of electroformed diodes with the thinnest Al2O3 acts as a microcavity in which the electromagnetic field due to SPPs stimulates EL from defect centers by the Purcell effect.
Large linear magnetoresistance and magnetothermopower in layered SrZnSb2
Authors: Wang Kefeng , Petrovic C.
Published: October 2012

We report the large linear magnetoresistance (∼300% in 9 T field at 2 K) and magnetothermopower in layered SrZnSb2 crystal with quasi-two-dimensional Sb layers. A crossover from the semiclassical parabolic field dependent magnetoresistance to linear field dependent magnetoresistance with increasing magnetic field is observed. The magnetoresistance behavior can be described very well by combining the semiclassical cyclotron contribution and the quantum limit magnetoresistance. Magnetic field also enhances the thermopower. Our results can be well understood by the magnetotransport of Dirac states in the bulk band structure.
Strain controlled systematic variation of metal-insulator transition in epitaxial NdNiO3 thin films
Authors: Kumar Yogesh , Choudhary R. J. , Kumar Ravi
Published: October 2012

We report here the strain dependent structural and electrical transport properties of epitaxial NdNiO3 thin films. Pulsed laser deposition technique was used to grow the NdNiO3 thin films on c-axis oriented SrTiO3 single crystals. Deposited films were irradiated using 200 MeV Ag15+ ion beam at the varying fluence (1 × 1011, 5 × 1011, and 1 × 1012 ions/cm2). X-ray diffraction studies confirm the epitaxial growth of the deposited films, which is maintained even up to the highest fluence. Rise in the in-plane compressive strain has been observed after the irradiation. All the films exhibit metal-insulator transition, however, a systematic decrease in the transition temperature (TMI) has been observed after irradiation, which may be attributed to the increase in the in-plane compression. Raman spectroscopy data reveal that this reduction in TMI, with the irradiation, is related to the decrease in band gap due to the stress generated by the in-plane compressive strain.
Mechanisms of damage formation in Eu-implanted AlN
Authors: Leclerc S. , Lacroix B. , Declémy A. , Lorenz K. , Ruterana P.
Published: October 2012

X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate the evolution of damage during implantation of 300 keV Eu ions at room temperature in AlN. At low fluence, a strain increase is observed in a buried layer where clusters of point defects and stacking faults (SFs) coexist. At higher fluence, a saturation of the strain is observed in this layer, and the XRD curves exhibit characteristic features which coupled with TEM results enable the identification of additional, spatially separated, dilated and contracted regions. From these observations, the following damage mechanisms are proposed. As the SFs grow by trapping point defects, a dense network of basal and prismatic SFs forms, which leads to the ejection of point defects from the buried damaged layer and consequently to the saturation of the strain. In this process, interstitials in excess migrate towards the undamaged bulk where they form clusters inducing large strain values. In contrast, defects ejected towards the surface either remain isolated or form isolated dislocation loops and SFs depending on their nature, i.e., interstitial or vacancy. This is probably the main difference with GaN where the defects ejected from the buried damaged layer contribute to the fast propagation of the dense SFs network towards the surface due to their relatively low formation energies. As a consequence, whilst nanocrystallization occurs at the surface of GaN, the relative confinement of defects and implanted atoms in the buried layer of AlN results in its amorphization, although at extremely high fluences (∼1017 Eu/cm2).
Rare earth luminescence: A way to overcome concentration quenching
Authors: Benz Felix , Strunk Horst P.
Published: October 2012

A model is developed to simulate the rare earth luminescence intensity in dependence of both the excitation rate and the dopant concentration. For low excitation rates, as in the case of photoluminescence investigations, concentration quenching is expected. In contrast for high excitation rates (as generally realized in cathodoluminescence experiments) concentration quenching can be suppressed and thus luminescence intensity increases with increasing dopant concentration. These results reconcile the recent photo- and cathodoluminescence results on GaN:Er presented by Chen et al. (APL 96, 181901, 2010)10.1063/1.3421535. Further experimental results indicate that the physical basis of the model is adequate.
Building research capacity in south-west Sydney through a Primary and Community Health Research Unit
Authors: Friesen Emma L. , Comino Elizabeth J. , Reath Jennifer , Derrett Alison , Johnson Maree , Davies Gawaine Powell , Teng-Liaw Siaw , Kemp Lynn
Published: October 2012

The Primary and Community Health Research Unit was established in 2010 in south-west Sydney to build research capacity in primary and community health services and help generate evidence to underpin clinical activities. In 2011, six project teams participated in a 12-month researcher mentoring program, undertaking projects in quality improvement and service evaluation. Project teams were linked with academic mentors and participated in four research skill development workshops covering research design, research ethics, statistical analysis and academic writing. All project teams presented their work at two or more research conferences, and all are preparing manuscripts for publication in peer-reviewed journals. The Primary and Community Health Research Unit’s approach to research capacity building in primary and community health services appears to be effective in supporting novice researchers to undertake research in their clinical settings. Sustainability is dependent on securing ongoing funding. Further analysis is needed to identify strengths and weaknesses of this approach.
Effect of heterogeneity in burn severity on Mexican fox squirrels following the return of fire
Authors: Doumas Sandra L. , Koprowski John L.
Published: October 2012

After decades of suppression, fire has returned to many forested areas of the western United States. Understanding responses of wildlife species to fire is essential to native species conservation because contemporary fires may not have the same effects as historical fires. Recent fires in the Chiricahua Mountains of Arizona provided an opportunity to investigate effects of fire heterogeneity on habitat selection of a native wildlife species. We used radiotelemetry to determine home ranges of Mexican fox squirrels (Sciurus nayaritensis chiricahuae) within fire-influenced forests. We then applied resource-utilisation functions to evaluate associations of use intensity within home ranges to heterogeneity of burn severity at two spatial scales. Squirrels used areas with moderate levels of burn heterogeneity at large scale more than areas of low or high heterogeneity. Squirrels used small (<0.5 ha) or narrow (<120 m) severely burnt patches, but incorporated only edges of large patches into home ranges. Use of burnt forests by Mexican fox squirrels demonstrates the complexities of fire’s effects on wildlife. Our results contribute to an understanding of the role and effect of fire in forest ecosystems and implications for wildlife conservation.
The Cobordism hypothesis
Authors: Freed Daniel
Published: October 2012

In this expository paper we introduce extended topological quantum field theories and the cobordism hypothesis.
Severe Outbreak of Downy Mildew Caused by Plasmopara obducens on Impatiens walleriana in Florida
Authors: Palmateer A. J. , Lopez P. , Seijo T. E. , Peres N. A. R.
Published: October 2012

Impatiens, Impatiens walleriana Hook.f., are grown as an ornamental crop in greenhouse and shade house production in Florida and other regions of the United States. Downy mildew on impatiens was detected from numerous landscapes (Manatee, Hillsborough, Collier, Hendry, Broward, Palm Beach, and Miami-Dade counties) in the winter of 2012. Incidence reached nearly 100% on many affected landscape plantings. Symptoms initially appeared as yellowing on the lower leaves and were typically vein-delineated, although in some cases the entire leaf was affected. Diseased plants later wilted and infected leaves abscised from the stem. A white, downy growth was apparent on the abaxial leaf surface. Microscopic observation revealed coenocytic mycelium with sporangiophores that were hyaline, thin-walled, and had slightly swollen bases. Branches of sporangiophores were monopodial and formed right angles to the supporting branches. Sporangia were hyaline and obvoid with a single pore on the distal ends that was mostly flat. Sporangia measured 19 to 22.5 × 13 to 17 μm. Oospores were observed in stem and leaf tissue. Leaves of 10 potted impatiens plants, I. walleriana ‘Super Elfin XP Coral’ and ‘Super Elfin XP White,’ were inoculated with a suspension containing 1 × 105 sporangia/ml and sprayed till runoff (approximately 20 ml per plant) with a handheld pressurized Ulva sprayer. Plants were maintained outside in a shade house under 73% shade where the daytime temperatures averaged 24°C and RH averaged 74% and nighttime temperature averaged 18°C with an average of 91% RH. Ten non-inoculated impatiens plants served as controls. After 10 days, symptoms typical of downy mildew occurred on 100% of the inoculated impatiens plants and sporulation was confirmed microscopically. The non-inoculated control plants remained healthy. The 5′ end of the large ribosomal subunit gene (762 bp) from two isolates, one collected in Hillsborough County and one from Miami-Dade County, was amplified by PCR (primers NL1-GCATATCAATAAGCGGAGGAAAAG and NL4-GGTCCGTGTTTCAAGACGG) and sequenced bi-directionally (1,2,3). The consensus sequence from both isolates was identical and it was deposited into GenBank (Accession No. JX217746). Sequence data matched (99% homology) with Plasmopara obducens reported on I. walleriana in Europe and Australia (1,2). To our knowledge, this is the first report of downy mildew on I. walleriana in Florida (4). The disease has made a major impact on impatiens in landscapes throughout Florida and will likely continue to affect future production.

References: (1) A. Bulajic et. al. Plant Dis. 95:491, 2011. (2) J. H. Cunnington et. al. Plant Pathol. 57:371, 2008. (3) K. O'Donnell. Curr. Genet. 22:213, 1992. (4) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, 1989.
Carbon Dioxide as a Potential Water Disinfestant for Phytophthora Disease Risk Mitigation
Authors: Kong Ping
Published: October 2012

The spread of Phytophthora spp. through irrigation systems and natural waterways can have a significant impact on plant health and requires mitigation. Pressurized carbon dioxide (CO2) can inactivate Phytophthora nicotianae zoospores but its effectiveness at low pressure and on other species was unknown. This study evaluated the effect of injected CO2 at 63 to 4,000 ppm in irrigation water on zoospore survival of four Phytophthora spp. and infectivity of P. nicotianae zoospores. Zoospore survival of P. nicotianae, P. tropicalis, and P. pini was reduced by over 90% at 4,000 ppm and was reduced by 40% at 125 to 2,000 ppm after a 2-h exposure. Survival of P. megasperma was less affected by injected CO2, with a reduction of 37.1% at ≤4,000 ppm. CO2 treatments at 4,000 ppm for 30 or 120 min of water infested with P. nicotianae at zoospore concentrations of 1,000 and 5,000 ml−1 reduced disease incidence of annual vinca (Catharanthus roseus) by 92 and 75%. Comparable efficacy was observed in the CO2 treatment at 2,000 ppm. The CO2 treatments at <2,000 ppm also significantly reduced disease caused by water infested at 1,000 zoospores ml−1. These results indicate that CO2 may have potential as a safe and effective water disinfestant for Phytophthora spp.
Acute Complications After Adult Spinal Deformity Surgery in Patients Aged 70 Years and Older
Authors: Lonergan Timothy , Place Howard , Taylor Patrick
Published: October 2012

Study Design/Setting:

This report is a retrospective case series that examined the acute complications of patients aged 70 years and older undergoing spinal deformity surgery that required fusion of at least 6 levels.

Objective:

To determine the acute complications that patients in the eighth decade of their life experience after spinal reconstructive surgery, and how these complication rates compare with other patient populations undergoing similar procedures.

Summary of Background Data:

As the mean age of the United States population rises, more older patients with painful spinal deformities can be expected. Although there are similar studies in the literature examining acute complications of patients undergoing major spinal deformity surgery, the complication rates of this unique patient population have not been adequately studied.

Methods:

Twenty patients had complete medical records with at least 6 months of follow-up. All the 20 patients underwent instrumented posterior spinal fusions performed by the same surgeon. Comorbidities, weighted comorbidity index, duration, number of hospital days, estimated blood loss, intensive care unit days, American Society of Anesthesiologist score, and intraoperative and postoperative complications were recorded.

Results:

The mean age of our patient cohort was 76.6 years (range, 70–84 y). Patients had an average of 4 comorbidities and an American Society of Anesthesiologist score of 2.7. Although the group of patients had a large number of comorbidities, their weighted comorbidity index, according to Charlson and colleagues, was fairly low at 1.05 (range, 0–4). All of the patients were fused at least 6 levels, with the average being 10.75 (range, 6–15). Ninety-five percent of patients experienced a complication of some type. Nine major complications occurred in 7 patients.

Conclusions:

Spinal deformity surgery in patients at any age has associated risks. These risks are believed to increase with age and the complexity of the procedure. Our results show that, although the risks of major complications are significant, the risk is not greater than in a younger population undergoing the similar procedures. We feel that age alone should not be a contraindication for patients in their eighth decade of life who are incapacitated by their painful spinal deformity.
Strategies to Fight Stigma toward People with Mental Disorders: Perspectives from Different Stakeholders
Authors: Corbière Marc , Samson Esther , Villotti Patrizia , Pelletier Jean-François
Published: October 2012

This study aims to provide a more complete and exhaustive perspective on the whole range of potential strategies to fight stigma by considering the perspectives of different stakeholders. Delegates to a Canadian conference were invited to participate in a survey that focused on stigma, from which the responses to the following question were analyzed: tell us briefly what you do to reduce prejudice and stigma toward people with a diagnosis of mental disorder? From 253 participants, 15 categories of strategies to fight stigma were identified from the verbatim (e.g., sharing/encouraging disclosure). These categories fell under six main themes: education, contact, protestation, person centered, working on recovery and social inclusion, and reflexive consciousness. The occurrence of these themes was different among stakeholders (clinical, organizational, and experiential knowledge). For example, people with mental disorders (experiential knowledge) often mentioned contact and person centered strategies, while mental health professionals (clinical knowledge) preferred education and working on recovery and social inclusion strategies. The results from this study highlight the need to pay more attention to the concept of disclosure of mental disorders in the process for de-stigmatization. Future studies are needed to assess the impact of the emerging strategies to fight stigma in the community.
Comparative Gastric Morphometry of Muong Indigenous and Vietnamese Wild Pigs
Authors: Trang Pham Hong , Ooi Peck Toung , Zuki Abu Bakar Zakaria , Noordin Mustapha Mohamed
Published: October 2012

It is hypothesized that despite sharing a similar habitat, the Muong indigenous and Vietnamese wild pigs may reveal different gastric morphology. Due to the protective nature of procuring these pigs, a total of 12 Muong indigenous pigs and nine Vietnamese wild pigs stomach collected post mortem were analysed for selected biometric parameters and histology. The result indicated that the stomach of the Vietnamese wild pig is broader with a bigger capacity and greater proportion of proper gastric glands. Interestingly, the stomach mass correlated well with live body weight in both breeds apart from possessing similar histomorphometry of the gastric gland regions. On the other hand, the thicker (P<0.05) submucosa in the Vietnamese wild pig is attributed to the presence of numerous loose connective tissues, abundant blood vessels, adipose tissues and nerve plexus. The appearance of lymphoid follicles underneath the tubular gastric glands in the Vietnamese wild pig exceeded that of Muong indigenous pigs. This finding suggested that the difference in feeding behavior as well as immunity. In conclusion, adaptations found in the Vietnamese wild pig indicated that this breed is equipped with a bigger and effectively functional stomach to suit its digestive physiology and immunity in the wild.
Genome-wide patterns of natural variation reveal strong selective sweeps and ongoing genomic conflict in Drosophila mauritiana
Authors: Nolte Viola , Pandey Ram Vinay , Kofler Robert , Schlötterer Christian
Published: October 2012

Although it is well understood that selection shapes the polymorphism pattern in Drosophila, signatures of classic selective sweeps are scarce. Here, we focus on Drosophila mauritiana, an island endemic, which is closely related to Drosophila melanogaster. Based on a new, annotated genome sequence, we characterized the genome-wide polymorphism by sequencing pooled individuals (Pool-seq). We show that the interplay between selection and recombination results in a genome-wide polymorphism pattern characteristic for D. mauritiana. Two large genomic regions (>500 kb) showed the signature of almost complete selective sweeps. We propose that the absence of population structure and limited geographic distribution could explain why such pronounced sweep patterns are restricted to D. mauritiana. Further evidence for strong adaptive evolution was detected for several nucleoporin genes, some of which were not previously identified as genes involved in genomic conflict. Since this adaptive evolution is continuing after the split of D. mauritiana and Drosophila simulans, we conclude that genomic conflict is not restricted to short episodes, but rather an ongoing process in Drosophila.
MASAC Consensus Conference: impediments to conducting clinical research in persons with haemophilia, von Willebrand's disease and rare bleeding disorders
Authors: Koerper M. A. , Frick N. , Kessler C. M.
Published: October 2012

A consensus conference conducted by the Medical and Scientific Advisory Council of the National Hemophilia Foundation was held in New Orleans, LA, on November 11, 2010, to discuss the impediments to conducting clinical research in persons with haemophilia, von Willebrand's disease and rare bleeding disorders. The conference combined presentations providing academic, non‐profit and industry perspectives with periods of open discussion. The objective of this conference was to identify the many challenges involved in facilitating U.S. Food and Drug Administration approval of innovative products for these patient populations.