3,513 research outputs found
Enhanced overall efficiency of GaInN-based light-emitting diodes with reduced efficiency droop by Al-composition-graded AlGaN/GaN superlattice electron blocking layer
AlxGa1-xN/GaN superlattice electron blocking layers (EBLs) with gradually decreasing Al composition toward the p-type GaN layer are introduced to GaInN-based high-power light-emitting diodes (LEDs). GaInN/GaN multiple quantum well LEDs with 5- and 9-period Al-composition-graded AlxGa1-xN/GaN EBL show comparable operating voltage, higher efficiency as well as less efficiency droop than LEDs having conventional bulk AlGaN EBL, which is attributed to the superlattice doping effect, enhanced hole injection into the active region, and reduced potential drop in the EBL by grading Al compositions. Simulation results reveal a reduction in electron leakage for the superlattice EBL, in agreement with experimental results. (C) 2013 AIP Publishing LLC.open1133sciescopu
Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat
The symmetry and structure of the superconducting gap in the Fe-based
superconductors are the central issue for understanding these novel materials.
So far the experimental data and theoretical models have been highly
controversial. Some experiments favor two or more constant or nearly-constant
gaps, others indicate strong anisotropy and yet others suggest gap zeros
("nodes"). Theoretical models also vary, suggesting that the absence or
presence of the nodes depends quantitatively on the model parameters. An
opinion that has gained substantial currency is that the gap structure, unlike
all other known superconductors, including cuprates, may be different in
different compounds within the same family. A unique method for addressing this
issue, one of the very few methods that are bulk and angle-resolved, calls for
measuring the electronic specific heat in a rotating magnetic field, as a
function of field orientation with respect to the crystallographic axes. In
this Communication we present the first such measurement for an Fe-based
high-Tc superconductor (FeBSC). We observed a fourfold oscillation of the
specific heat as a function of the in-plane magnetic field direction, which
allowed us to identify the locations of the gap minima (or nodes) on the Fermi
surface. Our results are consistent with the expectations of an extended s-wave
model with a significant gap anisotropy on the electron pockets and the gap
minima along the \Gamma M (or Fe-Fe bond) direction.Comment: 32 pages, 7 figure
Salford postgraduate annual research conference (SPARC) 2012 proceedings
These proceedings bring together a selection of papers from the 2012 Salford Postgraduate Annual Research Conference (SPARC). They reflect the breadth and diversity of research interests showcased at the conference, at which over 130 researchers from Salford, the North West and other UK universities presented their work. 21 papers are collated here from the humanities, arts, social sciences, health, engineering, environment and life sciences, built environment and business
Metabonomics and Intensive Care
This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901
Association between the cytokine storm, immune cell dynamics, and viral replicative capacity in hyperacute HIV infection
Introduction: Immunological damage in acute HIV infection (AHI) may predispose to detrimental clinical sequela.
However, studies on the earliest HIV-induced immunological changes are limited, particularly in sub-Saharan Africa.
We assessed the plasma cytokines kinetics, and their associations with virological and immunological parameters, in
a well-characterized AHI cohort where participants were diagnosed before peak viremia.
Methods: Blood cytokine levels were measured using Luminex and ELISA assays pre-infection, during the
hyperacute infection phase (before or at peak viremia, 1–11 days after the first detection of viremia), after peak
viremia (24–32 days), and during the early chronic phase (77–263 days). Gag-protease-driven replicative capacities of
the transmitted/founder viruses were determined using a green fluorescent reporter T cell assay. Complete blood
counts were determined before and immediately following AHI detection before ART initiation.
Results: Untreated AHI was associated with a cytokine storm of 12 out of the 33 cytokines analyzed. Initiation of
ART during Fiebig stages I–II abrogated the cytokine storm. In untreated AHI, virus replicative capacity correlated
positively with IP-10 (rho = 0.84, P < 0.001) and IFN-alpha (rho = 0.59, P = 0.045) and inversely with nadir CD4+ T cell
counts (rho = − 0.58, P = 0.048). Hyperacute HIV infection before the initiation of ART was associated with a transient
increase in monocytes (P < 0.001), decreased lymphocytes (P = 0.011) and eosinophils (P = 0.003) at Fiebig stages I–II,
and decreased eosinophils (P < 0.001) and basophils (P = 0.007) at Fiebig stages III–V. Levels of CXCL13 during the
untreated hyperacute phase correlated inversely with blood eosinophils (rho = − 0.89, P < 0.001), basophils (rho = −
0.87, P = 0.001) and lymphocytes (rho = − 0.81, P = 0.005), suggesting their trafficking into tissues. In early treated
individuals, time to viral load suppression correlated positively with plasma CXCL13 at the early chronic phase
(rho = 0.83, P = 0.042).
Conclusion: While commencement of ART during Fiebig stages I–II of AHI abrogated the HIV-induced cytokine
storm, significant depletions of eosinophils, basophils, and lymphocytes, as well as transient expansions of
monocytes, were still observed in these individuals in the hyperacute phase before the initiation of ART, suggesting
that even ART initiated during the onset of viremia does not abrogate all HIV-induced immune changes
Effect of Heat Treatment on Fracture Toughness ( K IC ) and Microstructure of a Fluorcanasite-Based Glass-Ceramic
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73358/1/j.1532-849X.2007.00233.x.pd
Existence and continuous dependence for weighted fractional differential equations with infinite delay
Basal Forebrain Mediated Increase in Brain CRF is Associated with Increased Cholinergic Tone and Depression
Major depression is a devastating disease that generates significant suffering and cost.
After controlling for the main effects of diagnosis and Cerebrospinal Fluid Corticotropin-Releasing Factor (CSF CRF), the interaction between CSF CRF and major depression disorder diagnosis was a significant predictor of basal forebrain cholinergic nuclei volume, but not of hippocampal volume.
By investigating both markers concurrently in participants with and without depression, we describe the extent to which the interaction between CSF CRF levels and depression diagnosis is associated with the volume of the forebrain cholinergic nuclei and of the hippocampus.
These results contribute to our understanding of the role of brain’s stress axis in depression
Food Security in the COVID-19 Era
Food insecurity is a national issue, one that affected 10.5% of households during some point of the year 2019. Those affected by food insecurity can have their access to food jeopardized due to financial hardship, eating patterns altered to prolong the food available, or various other adjustments including reliance on low-cost food, skipping meals, etc.
The state of Vermont is not immune to food insecurity, with a rate of 11.3% of households in 2018.
The Covid-19 pandemic created an unprecedented shift in daily life, with households having to rapidly adapt to meet newly imposed governmental regulations, including stay at home orders, while maintaining access to food essentials. This changed exacerbated food insecurity in already food-insecure households, while simultaneously creating food insecurity for those previously unaffected. A study focusing on food insecurity in Vermont from March to April 2020 found a 32.3% increase in food insecurity, with 35.5% of food-insecure households being previously food-secure.
This change highlighted not only the growing incidence of food insecurity, but also acknowledged the demographic change seen by newly food insecure households.
While this increase is dramatic and alarming, to our knowledge there is no research looking at the continuation of these trends regarding the impact of the Covid-19 pandemic on food insecurity in Vermont households. This lack of data indicates a need for continued follow up to best inform governmental agencies on both how Vermont households are being affected, and how regulations during summer & fall 2020 impacted the rise in food insecurity. These data will then provide guidance for future action to combat current and future food insecurity.https://scholarworks.uvm.edu/comphp_gallery/1304/thumbnail.jp
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ERK1/2 signaling dominates over RhoA signaling in regulating early changes in RNA expression induced by endothelin-1 in neonatal rat cardiomyocytes
Cardiomyocyte hypertrophy is associated with changes in gene expression. Extracellular signal-regulated kinases 1/2 (ERK1/2) and RhoA [activated by hypertrophic agonists (e.g. endothelin-1)] regulate gene expression and are implicated in the response, but their relative significance in regulating the cardiomyocyte transcriptome is unknown. Our aim was to establish the significance of ERK1/2 and/or RhoA in the early cardiomyocyte transcriptomic response to endothelin-1.Cardiomyocytes were exposed to endothelin-1 (1 h) with/without PD184352 (to inhibit ERK1/2) or C3 transferase (C3T, to inhibit RhoA). RNA expression was analyzed using microarrays and qPCR. ERK1/2 signaling positively regulated approximately 65% of the early gene expression response to ET-1 with a small (approximately 2%) negative effect, whereas RhoA signaling positively regulated approximately 10% of the early gene expression response to ET-1 with a greater (approximately 14%) negative contribution. Of RNAs non-responsive to endothelin-1, 66 or 448 were regulated by PD184352 or C3T, respectively, indicating that RhoA had a more significant effect on baseline RNA expression. mRNAs upregulated by endothelin-1 encoded a number of receptor ligands (e.g. Ereg, Areg, Hbegf) and transcription factors (e.g. Abra/Srf) that potentially propagate the response.ERK1/2 dominates over RhoA in the early transcriptomic response to endothelin-1. RhoA plays a major role in maintaining baseline RNA expression but, with upregulation of Abra/Srf by endothelin-1, RhoA may regulate changes in RNA expression over longer times. Our data identify ERK1/2 as a more significant node than RhoA in regulating the early stages of cardiomyocyte hypertrophy
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