787 research outputs found
Universal theory of nonlinear Luttinger liquids
One-dimensional quantum fluids are conventionally described by using an
effective hydrodynamic approach known as Luttinger liquid theory. As the
principal simplification, a generic spectrum of the constituent particles is
replaced by a linear one, which leads to a linear hydrodynamic theory. We show
that to describe the measurable dynamic response functions one needs to take
into account the nonlinearity of the generic spectrum and thus of the resulting
quantum hydrodynamic theory. This nonlinearity leads, for example, to a
qualitative change in the behavior of the spectral function. The universal
theory developed in this article is applicable to a wide class of
one-dimensional fermionic, bosonic, and spin systems.Comment: final published version with supporting online materia
3-Bromo-9-(4-chloroÂbenzÂyl)-9H-carbazole
The title compound, C19H13BrClN, was synthesized by N-alkylÂation of 4-chloro-1-(chloroÂmethÂyl)benzene with 3-bromo-9H-carbazole. The carbazole ring system is essentially planar, with a mean deviation of 0.028 Å, and it makes a dihedral angle of 91.2 (3) Å with the plane of the benzene ring
Learning Vision-Based Bipedal Locomotion for Challenging Terrain
Reinforcement learning (RL) for bipedal locomotion has recently demonstrated
robust gaits over moderate terrains using only proprioceptive sensing. However,
such blind controllers will fail in environments where robots must anticipate
and adapt to local terrain, which requires visual perception. In this paper, we
propose a fully-learned system that allows bipedal robots to react to local
terrain while maintaining commanded travel speed and direction. Our approach
first trains a controller in simulation using a heightmap expressed in the
robot's local frame. Next, data is collected in simulation to train a heightmap
predictor, whose input is the history of depth images and robot states. We
demonstrate that with appropriate domain randomization, this approach allows
for successful sim-to-real transfer with no explicit pose estimation and no
fine-tuning using real-world data. To the best of our knowledge, this is the
first example of sim-to-real learning for vision-based bipedal locomotion over
challenging terrains
Human Circulating MicroRNA-1 and MicroRNA-126 as Potential Novel Indicators for Acute Myocardial Infarction
Circulating miRNAs have been shown as promising biomarkers for various pathologic conditions. The aim of this study was to clarify that circulating miR-1 and miR-126 in human plasma might be useful as biomarkers in acute myocardial infarction (AMI). In our study, after pre-test, two candidate miRNAs were detected by using real-time RT-PCR. Cardiac troponin I (cTnI) concentrations were measured by ELISA assay in plasma from patients with AMI (n=17) and healthy subjects (n=25), simultaneously. Increased miR-1 and decreased miR-126 in plasma from patients with AMI after the onset of symptoms compared with healthy subjects were found. A remarkable finding in this study is that miR-1, miR-126 and cTnI expression levels exhibited the same trend. Our results suggest that the plasma concentrations of miR-1 and miR-126 may be useful indicators for AMI
β-AR Blockers Suppresses ER Stress in Cardiac Hypertrophy and Heart Failure
Long-term β-adrenergic receptor (β-AR) blockade reduces mortality in patients with heart failure. Chronic sympathetic hyperactivity in heart failure causes sustained β-AR activation, and this can deplete Ca(2+) in endoplasmic reticulum (ER) leading to ER stress and subsequent apoptosis. We tested the effect of β-AR blockers on ER stress pathway in experimental model of heart failure.ER chaperones were markedly increased in failing hearts of patients with end-stage heart failure. In Sprague-Dawley rats, cardiac hypertrophy and heart failure was induced by abdominal aortic constriction or isoproterenol subcutaneous injection. Oral β-AR blockers treatment was performed in therapy groups. Cardiac remodeling and left ventricular function were analyzed in rats failing hearts. After 4 or 8 weeks of banding, rats developed cardiac hypertrophy and failure. Cardiac expression of ER chaperones was significantly increased. Similar to the findings above, sustained isoproterenol infusion for 2 weeks induced cardiac hypertrophy and failure with increased ER chaperones and apoptosis in hearts. β-AR blockers treatment markedly attenuated these pathological changes and reduced ER stress and apoptosis in failing hearts. On the other hand, β-AR agonist isoproterenol induced ER stress and apoptosis in cultured cardiomyocytes. β-AR blockers largely prevented ER stress and protected myocytes against apoptosis. And β-AR blockade significantly suppressed the overactivation of CaMKII in isoproterenol-stimulated cardiomyocytes and failing hearts in rats.Our results demonstrated that ER stress occurred in failing hearts and this could be reversed by β-AR blockade. Alleviation of ER stress may be an important mechanism underlying the therapeutic effect of β-AR blockers on heart failure
Assessing Spatiotemporal Drought Dynamics and Its Related Environmental Issues in the Mekong River Delta
Drought is a major natural disaster that creates a negative impact on socio-economic development and environment. Drought indices are typically applied to characterize drought events in a meaningful way. This study aims at examining variations in agricultural drought severity based on the relationship between standardized ratio of actual and potential evapotranspiration (ET and PET), enhanced vegetation index (EVI), and land surface temperature (LST) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) platform. A new drought index, called the enhanced drought severity index (EDSI), was developed by applying spatiotemporal regression methods and time-series biophysical data derived from remote sensing. In addition, time-series trend analysis in the 2001–2018 period, along with the Mann–Kendal (MK) significance test and the Theil Sen (TS) slope, were used to examine the spatiotemporal dynamics of environmental parameters (i.e., LST, EVI, ET, and PET), and geographically weighted regression (GWR) was subsequently applied in order to analyze the local correlations among them. Results showed that a significant correlation was discovered among LST, EVI, ET, and PET, as well as their standardized ratios (|r| > 0.8, p 0.7 and a statistical significance p < 0.01. Besides, it was found that the temporal tendency of this phenomenon was the increase in intensity of drought, and that coastal areas in the study area were more vulnerable to this phenomenon. This study demonstrates the effectiveness of EDSI and the potential application of integrating spatial regression and time-series data for assessing regional drought conditions
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