1,125 research outputs found
Uniform high irradiance source
New 50 Kw xenon short arc lamp mounted within elliptical collector provides irradiance levels up to 4.4 x 10 to the 7th power watts/sq m with non-uniformity ratio of 3.30. Energy mixer or light pipe between lamp source and target improves non-uniformity to required ratio
Computerized analytical technique for design and analysis of a Sabatier reactor subsystem Final engineering report
Mathematical model for computerized evaluation of Sabatier reaction kinetics in oxygen recovery from carbon dioxid
Electron-electron interaction effects in quantum point contacts
We consider electron-electron interaction effects in quantum point contacts on the first quantization plateau, taking into account all scattering processes. We compute the low-temperature linear and nonlinear conductance, shot noise, and thermopower, by perturbation theory and a self-consistent nonperturbative method. On the conductance plateau, the low-temperature corrections are solely due to momentum-nonconserving processes that change the relative number of left- and right-moving electrons. This leads to a suppression of the conductance for increasing temperature or voltage. The size of the suppression is estimated for a realistic saddle-point potential, and is largest in the beginning of the conductance plateau. For large magnetic field, interaction effects are strongly suppressed by the Pauli principle, and hence the first spin-split conductance plateau has a much weaker interaction correction. For the nonperturbative calculations, we use a self-consistent nonequilibrium Green's function approach, which suggests that the conductance saturates at elevated temperatures. These results are consistent with many experimental observations related to the so-called 0.7 anomaly
Depressive symptoms in asymptomatic stage B heart failure with Type II diabetic mellitus.
BackgroundThe presence of concomitant Type II diabetic mellitus (T2DM) and depressive symptoms adversely affects individuals with symptomatic heart failure (HF).HypothesisIn presymptomatic stage B HF, this study hypothesized the presence of greater inflammation and depressive symptoms in T2DM as compared to non-T2DM Stage B patients.MethodsThis cross-sectional study examined clinical parameters, inflammatory biomarkers, and depressive symptoms in 349 T2DM and non-T2DM men with asymptomatic stage B HF (mean age 66.4 years ±10.1; range 30-91).ResultsFewer diabetic HF patients had left ventricular (LV) systolic dysfunction (P < .05) although more had LV diastolic dysfunction (P < .001). A higher percentage of T2DM HF patients were taking ACE-inhibitors, beta-blockers, calcium channel blockers, statins, and diuretics (P values < .05). T2DM HF patients had higher circulating levels of interleukin-6 (IL-6) (P < .01), tumor necrosis factor-alpha (P < .01), and soluble ST2 (sST2) (P < .01) and reported more somatic/affective depressive symptoms (Beck Depression Inventory II) (P < .05) but not cognitive/affective depressive symptoms (P = .20). Among all patients, in a multiple regression analysis predicting presence of somatic/affective depressive symptoms, sST2 (P = .026), IL-6 (P = .010), B-type natriuretic peptide (P = .016), and sleep (Pittsburgh Sleep Quality Index [P < .001]) were significant predictors (overall model F = 15.39, P < .001, adjusted R2 = .207).ConclusionsSomatic/affective but not cognitive/affective depressive symptoms are elevated in asymptomatic HF patients with T2DM patients. Linkages with elevated inflammatory and cardiac relevant biomarkers suggest shared pathophysiological mechanisms among T2DM HF patients with somatic depression, and these conditions are responsive to routine interventions, including behavioral. Copyright © 2019 John Wiley & Sons, Ltd
A clinical evaluation of extended wear contact lenses
A clinical evaluation of extended wear contact lense
Realized variance and market microstructure noise
We study market microstructure noise in high-frequency data and analyze its implications for the realized variance (RV) under a general specification for the noise. We show that kernel-based estimators can unearth important characteristics of market microstructure noise and that a simple kernel-based estimator dominates the RV for the estimation of integrated variance (IV). An empirical analysis of the Dow Jones Industrial Average stocks reveals that market microstructure noise is time-dependent and correlated with increments in the efficient price. This has important implications for volatility estimation based on high-frequency data. Finally, we apply cointegration techniques to decompose transaction prices and bid-ask quotes into an estimate of the efficient price and noise. This framework enables us to study the dynamic effects on transaction prices and quotes caused by changes in the efficient price
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Pentosan Polysulfate Decreases Myocardial Expression of the Extracellular Matrix Enzyme ADAMTS4 and Improves Cardiac Function In Vivo in Rats Subjected to Pressure Overload by Aortic Banding
Background: We hypothesized that cleavage of the extracellular matrix (ECM) proteoglycans versican and aggrecan by ADAMTS (a disintegrin and metalloprotease with thrombospondin motifs) proteases, which contributes to stress-induced ECM-reorganization in atherogenesis and osteoarthritis, also play a role in heart failure development. Objectives: The primary objective was to identify alterations in expression of ADAMTS versicanases and aggrecanases during development of heart failure, while evaluation of the effects of in vivo modulation of relevant changes in ADAMTS activity constituted the secondary objective. Methods: Myocardial levels of versican, aggrecan, and their ADAMTS cleaving proteases were examined in Wistar rats six weeks after aortic banding (AB), and versican and selected ADAMTS versicanases were further analyzed in neonatal cardiomyocytes (NCM) and cardiac fibroblasts (NFB) after stimulation by inflammatory mediators. Based on the initial findings, ADAMTS4 was selected the most promising therapeutic target. Thus, rats with AB were treated with pentosan polysulfate (PPS), a polysaccharide with known ADAMTS4-inhibitory properties, and effects on versican fragmentation, left ventricular function and geometry were evaluated. Results: We discovered that myocardial mRNA and protein levels of ADAMTS1 and -4, and mRNA levels of versican, aggrecan, and ADAMTS8 increased after AB, and TNF-α and IL-1β synergistically increased mRNA of versican and ADAMTS4 in NCM and NFB and secretion of ADAMTS4 from NCM. Furthermore, PPS-treatment improved systolic function, demonstrated by an improved fractional shortening (vehicle 48±3% versus PPS 60±1%, p<0.01) after AB. Following PPS-treatment, we observed an ∼80% reduction in myocardial ADAMTS4 mRNA (p = 0.03), and ∼50% reduction in the extracellular amount of the p150 versican fragments (p = 0.05), suggesting reduced versicanase activity. Conclusions: Our findings suggest that AB induces an increase in myocardial ADAMTS4 versicanase activity, and that PPS-treatment improved systolic function in the pressure-overloaded heart, holding promise as a novel therapeutic agent in heart failure
Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study
We calculate the intershell resistance R_{21} in a multiwall carbon nanotube
as a function of temperature T and Fermi level (e.g. a gate voltage), varying
the chirality of the inner and outer tubes. This is done in a so-called Coulomb
drag setup, where a current I_1 in one shell induces a voltage drop V_2 in
another shell by the screened Coulomb interaction between the shells neglecting
the intershell tunnelling. We provide benchmark results for R_{21}=V_2/I_1
within the Fermi liquid theory using Boltzmann equations. The band structure
gives rise to strongly chirality dependent suppression effects for the Coulomb
drag between different tubes due to selection rules combined with mismatching
of wave vector and crystal angular momentum conservation near the Fermi level.
This gives rise to orders of magnitude changes in R_{21} and even the sign of
R_{21} can change depending on the chirality of the inner and outer tube and
misalignment of inner and outer tube Fermi levels. However for any tube
combination, we predict a dip (or peak) in R_{21} as a function of gate
voltage, since R_{21} vanishes at the electron-hole symmetry point. As a
byproduct, we classified all metallic tubes into either zigzag-like or
armchair-like, which have two different non-zero crystal angular momenta m_a,
m_b and only zero angular momentum, respectively.Comment: 17 pages, 10 figure
Secretoneurin Is an Endogenous Calcium/Calmodulin-Dependent Protein Kinase II Inhibitor That Attenuates Ca2+-Dependent Arrhythmia
BACKGROUND: Circulating SN (secretoneurin) concentrations are increased in patients with myocardial dysfunction and predict poor outcome. Because SN inhibits CaMKII delta (Ca2+/calmodulin-dependent protein kinase II delta) activity, we hypothesized that upregulation of SN in patients protects against cardiomyocyte mechanisms of arrhythmia. METHODS: Circulating levels of SN and other biomarkers were assessed in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT; n=8) and in resuscitated patients after ventricular arrhythmia-induced cardiac arrest (n=155). In vivo effects of SN were investigated in CPVT mice (RyR2 [ryanodine receptor 2]-R2474S) using adeno-associated virus-9-induced overexpression. Interactions between SN and CaMKII delta were mapped using pull-down experiments, mutagenesis, ELISA, and structural homology modeling. Ex vivo actions were tested in Langendorff hearts and effects on Ca2+ homeostasis examined by fluorescence (fluo-4) and patchclamp recordings in isolated cardiomyocytes. RESULTS: SN levels were elevated in patients with CPVT and following ventricular arrhythmia-induced cardiac arrest. In contrast to NT-proBNP (N-terminal proB- type natriuretic peptide) and hs-TnT (high-sensitivity troponin T), circulating SN levels declined after resuscitation, as the risk of a new arrhythmia waned. Myocardial pro-SN expression was also increased in CPVT mice, and further adeno-associated virus-9-induced overexpression of SN attenuated arrhythmic induction during stress testing with isoproterenol. Mechanistic studies mapped SN binding to the substrate binding site in the catalytic region of CaMKII delta. Accordingly, SN attenuated isoproterenol induced autophosphorylation of Thr287-CaMKII delta in Langendorff hearts and inhibited CaMKII delta-dependent RyR phosphorylation. In line with CaMKII delta and RyR inhibition, SN treatment decreased Ca2+ spark frequency and dimensions in cardiomyocytes during isoproterenol challenge, and reduced the incidence of Ca2+ waves, delayed afterdepolarizations, and spontaneous action potentials. SN treatment also lowered the incidence of early afterdepolarizations during isoproterenol; an effect paralleled by reduced magnitude of L-type Ca2+ current. CONCLUSIONS: SN production is upregulated in conditions with cardiomyocyte Ca2+ dysregulation and offers compensatory protection against cardiomyocyte mechanisms of arrhythmia, which may underlie its putative use as a biomarker in at-risk patients.Peer reviewe
Syndecan-4 signaling via NFAT regulates extracellular matrix production and cardiac myofibroblast differentiation in response to mechanical stress
Pressure overload activates cardiac fibroblasts leading to excessive production of extracellular matrix which may contribute to compromised heart function. The activated fibroblast acquires smooth muscle-like features such as expression of smooth muscle alpha-actin (SMA) and SM22 and is therefore referred to as myofibroblast. The molecular mechanisms underlying mechanical stress-induced myofibroblast differentiation are poorly defined. The objective of this study was to examine the potential roles of the transmembrane proteoglycan syndecan-4 and the calcineurin-dependent transcription factor nuclear factor of activated T-cells (NFAT) in myofibroblast differentiation. Aortic banding resulted in elevated collagen land III, fibronectin, SMA and SM22 mRNA in the left ventricles of wild-type mice, whereas this response was markedly reduced in syndecan-4(-/-) mice. Myofibroblast differentiation in vitro was associated with increased SMA, collagen I and III expression and NFAT-luciferase activity, all of which were reduced in fibroblasts from syndecan-4(-/-) mice or after treatment with calcineurin/NFAT blockers. Following cyclic stretch, NFATc4 was activated in cardiac fibroblasts in a syndecan-4- and calcineurin-dependent manner. Syndecan-4 and calcineurin co-localized and mechanical stress resulted in dephosphorylation of serine179 of syndecan-4, an intracellular residue critical for calcineurin interaction. Over-expression of NFATc4 up-regulated collagen III, MRTF-A (a transcriptional regulator of SMA) and the NFAT-target regulator of calcineurin 1.4 (RCAN1.4). Our data demonstrate that syndecan-4 is important for the differentiation of cardiac fibroblasts into myofibroblasts in the pressure-overloaded heart and that the calcineurin/NFAT pathway is engaged upon mechanical stress in a syndecan-4-dependent manner, playing an active role in myofibroblast differentiation and extracellular matrix production. This article is part of a Special Issue entitled 'Possible Editorial'. (c) 2012 Elsevier Ltd. All rights reserved
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