61 research outputs found
Quantum fields in disequilibrium: neutral scalar bosons with long-range, inhomogeneous perturbations
Using Schwinger's quantum action principle, dispersion relations are obtained
for neutral scalar mesons interacting with bi-local sources. These relations
are used as the basis of a method for representing the effect of interactions
in the Gaussian approximation to field theory, and it is argued that a marked
inhomogeneity, in space-time dependence of the sources, forces a discrete
spectrum on the field. The development of such a system is characterized by
features commonly associated with chaos and self-organization (localization by
domain or cell formation). The Green functions play the role of an iterative
map in phase space. Stable systems reside at the fixed points of the map. The
present work can be applied to self-interacting theories by choosing suitable
properties for the sources. Rapid transport leads to a second order phase
transition and anomalous dispersion. Finally, it is shown that there is a
compact representation of the non-equilibrium dynamics in terms of generalized
chemical potentials, or equivalently as a pseudo-gauge theory, with an
imaginary charge. This analogy shows, more clearly, how dissipation and entropy
production are related to the source picture and transform a flip-flop like
behaviour between two reservoirs into the Landau problem in a constant
`magnetic field'. A summary of conventions and formalism is provided as a basis
for future work.Comment: 23 pages revte
Quasinormal modes of Schwarzschild black holes in four and higher dimensions
We make a thorough investigation of the asymptotic quasinormal modes of the
four and five-dimensional Schwarzschild black hole for scalar, electromagnetic
and gravitational perturbations. Our numerical results give full support to all
the analytical predictions by Motl and Neitzke, for the leading term. We also
compute the first order corrections analytically, by extending to higher
dimensions, previous work of Musiri and Siopsis, and find excellent agreement
with the numerical results. For generic spacetime dimension number D the
first-order corrections go as . This means that
there is a more rapid convergence to the asymptotic value for the five
dimensional case than for the four dimensional case, as we also show
numerically.Comment: 12 pages, 5 figures, RevTeX4. v2. Typos corrected, references adde
Genetic Sharing with Cardiovascular Disease Risk Factors and Diabetes Reveals Novel Bone Mineral Density Loci.
Bone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR) method to identify single nucleotide polymorphisms (SNPs) associated with BMD by leveraging cardiovascular disease (CVD) associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD) at conditional FDR < 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity
Universal hierarchical symmetry for turbulence and general multi-scale fluctuation systems
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
Fine-tuning of defensive behaviors in the dorsal periaqueductal gray by atypical neurotransmitters
an E Performance Analysis of ETDGE; cient andUnbiased TDOA Estimator H.C. So y and P.C. Ching
A computationally e cient estimator is proposed which can provide instantaneous delay measurement for many practical applications such as radar, sonar and geolocation via satellites. It consists of an adaptive FIR lter to model the time di erence of arrival (TDOA) between the received signals from two sensors and a variable gain to adapt to the changing signal-to-noise ratio environment. The TDOA is obtained directly on a sample-by-sample basis and no interpolation is necessary. The proposed algorithm gives an unbiased delay estimate and its performance for both stationary and nonstationary conditions is evaluated rigorously. Itisalsoproved that the least squares realization of the estimator attains the Cramer-Rao lower bound. indexing terms: time di erence of arrival, adaptive signal processing Corresponding Author
An RNN Based Speech Recognition System with Discriminative Training
In our previous work [1], a novel method of utilizing a set of fully connected recurrent neural networks (RNNs) for speech modeling has been proposed. Despite the effectiveness of the RNN model in characterizing individual speech units, the system performs less satisfactorily for speech recognition due to poor discrimination between models. In this paper, an efficient discriminative training procedure is developed for the RNN based recognition system. By using discriminative training, each RNN speech model is adjusted to reduce its distance from the designated speech unit while increase distances from the others. In addition, a duration-screening process is introduced to enhance the discriminating power of the recognition system. Speaker-dependent recognition experiments have been carried out for 1) 11 isolated Cantonese digits, 2) 58 very confusing Cantonese CV syllables, and 3) 20 English isolated words. The recognition rates attained are 90.9%, 86.7% and 93.5% respectively. I. Intr..
Approximate Maximum Likelihood Delay Estimation via Orthogonal Wavelet Transform
A novel approximate maximum likelihood algorithm is proposed for estimating the time difference of arrival between signals received at two spatially separated sensors. Prior to cross correlation, one of the channel outputs is optimally weighted at different frequency bands with the use of an orthogonal wavelet transform. It composes an array of multirate filters and is a time domain implementation of the generalized cross correlation method. However, it does not suffer from the performance degradation due to the errors inherent in spectral estimation obtained from finite length data and is computationally efficient. A simple decision rule is also provided for automatically determining the requisite levels of wavelet decomposition. The effectiveness of the method is demonstrated by comparing with the direct cross correlator, the Eckart processor and the Cram'er-Rao lower bound for different noise conditions and wavelet filter lengths. Corresponding Author: H. C. So Department of Electro..
Characteristics of lightweight aggregate produced from lime-treated sewage sludge and palm oil fuel ash
This study investigated the characteristics of lightweight aggregate made from solid waste such as lime-treated sewage sludge, palm oil fuel ash and sodium silicate. These aggregates are produced via sintering at three temperatures of 1160, 1180 and 1200 °C. The properties of sintered pellets namely bulk density, particle density, water absorption, shrinkage index and crushing strength are determined. The properties of the aggregates changed with the addition of binder and firing conditions. The increase of binder content and sintering temperature increased the strength and particle density, and also decreased the water absorption due to the formation of a dense structure. © 2017 Elsevier Lt
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