48 research outputs found

    Is the Core-cusp Problem a Matter of Perspective? Jeans Anisotropic Modeling against Numerical Simulations

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    Mock member stars for 28 dwarf galaxies are constructed from the cosmological auriga simulation, which reflects the dynamical status of realistic stellar tracers. Axisymmetric Jeans Anisotropic Multi-Gaussian Expansion (jam) modeling is applied to 6000 star particles for each system to recover the underlying matter distribution. The stellar or dark matter component individually is poorly recovered, but the total profile is constrained more reasonably. The mass within the half-mass radius of tracers is recovered the tightest, and the mass between 200 and 300 pc, M(200–300 pc), is an unbiasedly constrained ensemble, with a scatter of 0.167 dex. If using 2000 particles and only line-of-sight velocities with typical errors, the scatter in M(200–300 pc) is increased by ∼50%. Quiescent Saggitarius dSph–like systems and star-forming systems with strong outflows show distinct features, with M(200–300 pc) mostly underestimated for the former, and likely overestimated for the latter. The biases correlate with the dynamical status, which is a result of contraction motions due to tidal effects in quiescent systems or galactic winds in star-forming systems, driving them out of equilibrium. After including Gaia DR3 proper motion errors, we find proper motions can be as useful as line-of-sight velocities for nearby systems at < ∼60 kpc. By extrapolating the actual density profiles and the dynamical constraints down to scales below the resolution, we find the mass within 150 pc can be an unbiasedly constrained ensemble, with a scatter of ∼0.255 dex. We show that the contraction of member stars in nearby systems is detectable based on Gaia DR3 proper motion errors

    The United States COVID-19 Forecast Hub dataset

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    Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages

    Two Lysine Sites That Can Be Malonylated Are Important for LuxS Regulatory Roles in Bacillus velezensis

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    S-ribosylhomocysteine lyase (LuxS) has been shown to regulate bacterial multicellular behaviors, typically biofilm formation. However, the mechanisms for the regulation are still mysterious. We previously identified a malonylation modification on K124 and K130 of the LuxS in the plant growth-promoting rhizobacterium B. velezensis (FZB42). In this work, we investigated the effects of the two malonylation sites on biofilm formation and other biological characteristics of FZB42. The results showed that the K124R mutation could severely impair biofilm formation, swarming, and sporulation but promote AI-2 production, suggesting inhibitory effects of high-level AI-2 on the features. All mutations (K124R, K124E, K130R, and K130E) suppressed FZB42 sporulation but increased its antibiotic production. The double mutations generally had a synergistic effect or at least equal to the effects of the single mutations. The mutation of K130 but not of K124 decreased the in vitro enzymatic activity of LuxS, corresponding to the conservation of K130 among various Bacillus LuxS proteins. From the results, we deduce that an alternative regulatory circuit may exist to compensate for the roles of LuxS upon its disruption. This study broadens the understanding of the biological function of LuxS in bacilli and underlines the importance of the two post-translational modification sites.Peer Reviewe

    Multi-Omics Analysis of the Mechanism of Mentha Haplocalyx Briq on the Growth and Metabolic Regulation of Fattening Sheep

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    Mentha haplocalyx Briq (MHB) and its components have been proven to improve the growth performance of livestock and poultry. The aim of this experiment was to investigate the effects of MHB addition on growth performance, rumen and fecal microbiota, rumen fluid, serum and urine metabolism, and transcriptomics of rumen epithelial cells in meat sheep. Twelve Hu sheep were selected for the experiment and fed with basic diet (CON) and a basal diet supplemented with 80 g/kg DM of Mentha haplocalyx Briq (MHB). The experimental period was 10 weeks with the first 2 weeks as the pre-trial period. The results showed that compared with the CON group, the average daily weight gain of meat sheep in the MHB group increased by 20.1%; the total volatile fatty acid (VFA) concentration significantly increased (p p p p p p p p p p < 0.05), which had a significant impact on protein synthesis and energy metabolism. The transcriptome sequencing results showed that differentially expressed genes were mainly enriched in immune regulation, energy metabolism, and protein modification. Therefore, adding MHB improved the growth performance of lambs by altering rumen and intestinal microbiota, rumen, serum and urine metabolomics, and transcriptome

    A novel square-root adaptive unscented Kalman filtering method for accurate state-of-charge estimation of lithium-ion batteries.

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    The accurate state-of-charge estimation of the lithium-ion battery is one of the key technologies to benchmark the rapid development of new energy vehicles. Unscented Kalman filtering abandons the traditional way of forcing the system to linearize, selects the symmetric sampling strategy to obtain sampling points, and uses Unscented Transformation to deal with the nonlinear transfer of mean and covariance. Then calculate the statistical properties of nonlinear functions with the corresponding weights of each sampling point. However, the traditional unscented Kalman filtering has accumulated errors due to a large number of calculations, the covariance matrix is easy to diverge due to the inability to perform QR decomposition, and the system has deviations caused by unknown noise, resulting in low stability and easy divergence of the state-of-charge estimation results. Based on the second-order RC equivalent circuit model, a square-root adaptive unscented Kalman filtering is proposed, which replaces the state error covariance matrix with the square root of the state error covariance matrix. The noise covariance is updated in real-time to improve the tracking and convergence of state-of-charge estimation results. The algorithm is verified by the Hybrid Pulse Power Characterization test (HPPC) and Beijing Bus Dynamic Stress Test (BBDST) working conditions. The results show that square-root adaptive unscented Kalman filtering can improve the estimation accuracy of state-of-charge under complex working conditions

    Microstructural evolution of whipped cream in whipping process observed by confocal laser scanning microscopy

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    It is useful to carefully observe the evolution of foam structures to elucidate the factors affecting cream during whipping. In this study, confocal laser scanning microscopy and a double dyeing technology were used to investigate the microstructural evolution of a rigid foam structure in whipped cream. The location of fat and proteins were determined according to the signals they produce at different characteristic wavelengths. Protein membranes on the surface of air bubbles were clearly observed. A simple yet comprehensive characterization of the whipping process was established according to the micrographs and supported by relevant theories. The formation of a rigid foam structure depends on foaming of the protein in the plasma phase and partial coalescence of fat globules. The formation of protein foam in the cream, creation of net structure, and system breakage and collapse phenomena occurring throughout the whole whipping evolution process was depicted and distinguished visually by different colors
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