105 research outputs found
Quantitative Amenability for Actions of Finitely Generated Groups
We generalize the notion of isoperimetric profiles of finitely generated
groups to their actions by measuring the boundary of finite subgraphings of the
orbit graphing. We prove that like the classical isoperimetric profiles for
groups, decay of the isoperimetric profile for the essentially-free action is
equivalent to amenability of the action in the sense of Zimmer. For
measure-preserving actions, we find the bounds between the original and
generalized isoperimetric profiles for measure-preserving actions.Comment: 12 page
Markovian and non-Markovian master equations versus an exactly solvable model of a qubit in a cavity
Quantum master equations are commonly used to model the dynamics of open
quantum systems, but their accuracy is rarely compared with the analytical
solution of exactly solvable models. In this work, we perform such a comparison
for the damped Jaynes-Cummings model of a qubit in a leaky cavity, for which an
analytical solution is available in the one-excitation subspace. We consider
the non-Markovian time-convolutionless master equation up to the second
(Redfield) and fourth orders as well as three types of Markovian master
equations: the coarse-grained, cumulant, and standard rotating-wave
approximation (RWA) Lindblad equations. We compare the exact solution to these
master equations for three different spectral densities: impulse, Ohmic, and
triangular. We demonstrate that the coarse-grained master equation outperforms
the standard RWA-based Lindblad master equation for weak coupling or high qubit
frequency (relative to the spectral density high-frequency cutoff ),
where the Markovian approximation is valid. In the presence of non-Markovian
effects characterized by oscillatory, non-decaying behavior, the TCL
approximation closely matches the exact solution for short evolution times (in
units of ) even outside the regime of validity of the Markovian
approximations. For long evolution times, all master equations perform poorly,
as quantified in terms of the trace-norm distance from the exact solution. The
fourth-order time-convolutionless master equation achieves the top performance
in all cases. Our results highlight the need for reliable approximation methods
to describe open-system quantum dynamics beyond the short-time limit.Comment: 28 pages, 9 figures. v2: added new reference
Relations of blood lead levels to echocardiographic left ventricular structure and function in preschool children
Lead (Pb) has been proved to exert adverse effect on human cardiovascular system. However, the cardiotoxicity of Pb on children is still unclear. The aim of this study was to evaluate left ventricular (LV) structure and function, by using echocardiographic indices, in order to elucidate the effect of Pb on low-grade inflammation related to left ventricle in healthy preschool children. We recruited a total of 486 preschool children, 310 from Guiyu (e-waste-exposed area) and 176 from Haojiang (reference area). Blood Pb levels, complete blood counts, and LV parameters were evaluated. Associations between blood Pb levels and LV parameters and peripheral leukocyte counts were analyzed using linear regression models. The median blood level of Pb and the counts of white blood cells (WBCs), monocytes, and neutrophils were higher in exposed group. In addition, the exposed group showed smaller left ventricle (including interventricular septum, LV posterior wall, and LV mass index) and impaired LV systolic function (including LV fractional shortening and LV ejection fraction) regardless gender. After adjustment for confounding factors, elevated blood Pb levels were significantly associated with higher counts of WBCs and neutrophils, and lower levels of LV parameters. Furthermore, counts of WBCs, monocytes, and neutrophils were negatively correlated with LV parameters. Taken together, smaller left ventricle and impaired systolic function were found in e-waste-exposed children and associated with chronic low-grade inflammation and elevated blood Pb levels. It indicates that the heart health of e-waste-exposed children is at risk due to the long-term environmental chemical insults. (C) 2020 Elsevier Ltd. All rights reserved
Information recoverability of noisy quantum states
Extracting classical information from quantum systems is an essential step of many quantum algorithms. However, this information could be corrupted as the systems are prone to quantum noises, and its distortion under quantum dynamics has not been adequately investigated. In this work, we introduce a systematic framework to study how well we can retrieve information from noisy quantum states. Given a noisy quantum channel, we fully characterize the range of recoverable classical information. This condition allows a natural measure quantifying the information recoverability of a channel. Moreover, we resolve the minimum information retrieving cost, which, along with the corresponding optimal protocol, is efficiently computable by semidefinite programming. As applications, we establish the limits on the information retrieving cost for practical quantum noises and employ the corresponding protocols to mitigate errors in ground state energy estimation. Our work gives the first full characterization of information recoverability of noisy quantum states from the recoverable range to the recovering cost, revealing the ultimate limit of probabilistic error cancellation
Two-stage Neural Network for ICASSP 2023 Speech Signal Improvement Challenge
In ICASSP 2023 speech signal improvement challenge, we developed a dual-stage
neural model which improves speech signal quality induced by different
distortions in a stage-wise divide-and-conquer fashion. Specifically, in the
first stage, the speech improvement network focuses on recovering the missing
components of the spectrum, while in the second stage, our model aims to
further suppress noise, reverberation, and artifacts introduced by the
first-stage model. Achieving 0.446 in the final score and 0.517 in the P.835
score, our system ranks 4th in the non-real-time track.Comment: Accepted by ICASSP 202
GLM-130B: An Open Bilingual Pre-trained Model
We introduce GLM-130B, a bilingual (English and Chinese) pre-trained language
model with 130 billion parameters. It is an attempt to open-source a 100B-scale
model at least as good as GPT-3 (davinci) and unveil how models of such a scale
can be successfully pre-trained. Over the course of this effort, we face
numerous unexpected technical and engineering challenges, particularly on loss
spikes and divergence. In this paper, we introduce the training process of
GLM-130B including its design choices, training strategies for both efficiency
and stability, and engineering efforts. The resultant GLM-130B model offers
significant outperformance over GPT-3 175B (davinci) on a wide range of popular
English benchmarks while the performance advantage is not observed in OPT-175B
and BLOOM-176B. It also consistently and significantly outperforms ERNIE TITAN
3.0 260B -- the largest Chinese language model -- across related benchmarks.
Finally, we leverage a unique scaling property of GLM-130B to reach INT4
quantization without post training, with almost no performance loss, making it
the first among 100B-scale models and more importantly, allowing its effective
inference on 4RTX 3090 (24G) or 8RTX 2080 Ti (11G) GPUs, the
most affordable GPUs required for using 100B-scale models. The GLM-130B model
weights are publicly accessible and its code, training logs, related toolkit,
and lessons learned are open-sourced at
\url{https://github.com/THUDM/GLM-130B/}.Comment: Accepted to ICLR 202
Comparison of the transcriptome and metabolome of wheat (Triticum aestivum L.) proteins content during grain formation provides insight
IntroductionWheat is a food crop with a large global cultivation area, and the content and quality of wheat glutenin accumulation are important indicators of the quality of wheat flour.MethodsTo elucidate the gene expression regulation and metabolic characteristics related to the gluten content during wheat grain formation, transcriptomic and metabolomic analyses were performed for the high gluten content of the Xinchun 26 cultivar and the low proteins content of the Xinchun 34 cultivar at three periods (7 d, 14 d and 21 d) after flowering.ResultsTranscriptomic analysis revealed that 5573 unique differentially expressed genes (DEGs) were divided into two categories according to their expression patterns during the three periods. The metabolites detected were mainly divided into 12 classes. Lipid and lipid-like molecule levels and phenylpropanoid and polyketide levels were the highest, and the difference analysis revealed a total of 10 differentially regulated metabolites (DRMs) over the three periods. Joint analysis revealed that the DEGs and DRMs were significantly enriched in starch and sucrose metabolism; the citrate cycle; carbon fixation in photosynthetic organisms; and alanine, aspartate and glutamate metabolism pathways. The genes and contents of the sucrose and gluten synthesis pathways were analysed, and the correlation between gluten content and its related genes was calculated. Based on weighted correlation network analysis (WGCNA), by constructing a coexpression network, a total of 5 specific modules and 8 candidate genes that were strongly correlated with the three developmental stages of wheat grain were identified.DiscussionThis study provides new insights into the role of glutenin content in wheat grain formation and reveals potential regulatory pathways and candidate genes involved in this developmental process
Ethnic and Racial Differences in Self-reported Symptoms, Health Status, Activity Level, and Missed Work at 3 and 6 Months Following SARS-CoV-2 Infection
INTRODUCTION: Data on ethnic and racial differences in symptoms and health-related impacts following SARS-CoV-2 infection are limited. We aimed to estimate the ethnic and racial differences in symptoms and health-related impacts 3 and 6 months after the first SARS-CoV-2 infection.
METHODS: Participants included adults with SARS-CoV-2 infection enrolled in a prospective multicenter US study between 12/11/2020 and 7/4/2022 as the primary cohort of interest, as well as a SARS-CoV-2-negative cohort to account for non-SARS-CoV-2-infection impacts, who completed enrollment and 3-month surveys (
RESULTS: Following SARS-CoV-2 infection, the majority of symptoms were similar over time between ethnic and racial groups. At 3 months, Hispanic participants were more likely than non-Hispanic participants to report fair/poor health (OR: 1.94; 95%CI: 1.36-2.78) and reduced activity (somewhat less, OR: 1.47; 95%CI: 1.06-2.02; much less, OR: 2.23; 95%CI: 1.38-3.61). At 6 months, differences by ethnicity were not present. At 3 months, Other/Multiple race participants were more likely than white participants to report fair/poor health (OR: 1.90; 95% CI: 1.25-2.88), reduced activity (somewhat less, OR: 1.72; 95%CI: 1.21-2.46; much less, OR: 2.08; 95%CI: 1.18-3.65). At 6 months, Asian participants were more likely than white participants to report fair/poor health (OR: 1.88; 95%CI: 1.13-3.12); Black participants reported more missed work (OR, 2.83; 95%CI: 1.60-5.00); and Other/Multiple race participants reported more fair/poor health (OR: 1.83; 95%CI: 1.10-3.05), reduced activity (somewhat less, OR: 1.60; 95%CI: 1.02-2.51; much less, OR: 2.49; 95%CI: 1.40-4.44), and more missed work (OR: 2.25; 95%CI: 1.27-3.98).
DISCUSSION: Awareness of ethnic and racial differences in outcomes following SARS-CoV-2 infection may inform clinical and public health efforts to advance health equity in long-term outcomes
Information recoverability of noisy quantum states
Extracting classical information from quantum systems is an essential step of
many quantum algorithms. However, this information could be corrupted as the
systems are prone to quantum noises, and its distortion under quantum dynamics
has not been adequately investigated. In this work, we introduce a systematic
framework to study how well we can retrieve information from noisy quantum
states. Given a noisy quantum channel, we fully characterize the range of
recoverable classical information. This condition allows a natural measure
quantifying the information recoverability of a channel. Moreover, we resolve
the minimum information retrieving cost, which, along with the corresponding
optimal protocol, is efficiently computable by semidefinite programming. As
applications, we establish the limits on the information retrieving cost for
practical quantum noises and employ the corresponding protocols to mitigate
errors in ground state energy estimation.Comment: 18 pages including appendi
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