1,687 research outputs found
Different asymptotic behaviors of thick branes in mimetic gravity
In this paper, thick branes generated by mimetic scalar field with Lagrange
multiplier formulation are investigated. We give three typical thick brane
background solutions with different asymptotic behaviors and show that all the
solutions are stable under tensor perturbations. The effective potentials of
the tensor perturbations exhibit as volcano potential, P\"{o}schl-Teller
potential, and harmonic oscillator potential for the three background
solutions, respectively. All the tensor zero modes (massless gravitons) of the
three cases can be localized on the brane. We also calculate the corrections to
the Newtonian potential. On a large scale, the corrections to the Newtonian
potential can be ignored. While on a small scale, the correction from the
volcano-like potential is more pronounced than the other two cases. Combining
the latest results of short-range gravity experiments that the usual Newtonian
potential holds down to a length scale at m, we get the
constraint on the scale parameter as eV, and constraint on
the corresponding five-dimensional fundamental scale as TeV.Comment: 9 pages, 9 fugure
Gain Scheduling Control of Nonlinear Shock Motion Based on Equilibrium Manifold Linearization Model
AbstractThe equilibrium manifold linearization model of nonlinear shock motion is of higher accuracy and lower complexity over other models such as the small perturbation model and the piecewise-linear model. This paper analyzes the physical significance of the equilibrium manifold linearization model, and the self-feedback mechanism of shock motion is revealed. This helps to describe the stability and dynamics of shock motion. Based on the model, the paper puts forwards a gain scheduling control method for nonlinear shock motion. Simulation has shown the validity of the control scheme
TRACE: 5D Temporal Regression of Avatars with Dynamic Cameras in 3D Environments
Although the estimation of 3D human pose and shape (HPS) is rapidly
progressing, current methods still cannot reliably estimate moving humans in
global coordinates, which is critical for many applications. This is
particularly challenging when the camera is also moving, entangling human and
camera motion. To address these issues, we adopt a novel 5D representation
(space, time, and identity) that enables end-to-end reasoning about people in
scenes. Our method, called TRACE, introduces several novel architectural
components. Most importantly, it uses two new "maps" to reason about the 3D
trajectory of people over time in camera, and world, coordinates. An additional
memory unit enables persistent tracking of people even during long occlusions.
TRACE is the first one-stage method to jointly recover and track 3D humans in
global coordinates from dynamic cameras. By training it end-to-end, and using
full image information, TRACE achieves state-of-the-art performance on tracking
and HPS benchmarks. The code and dataset are released for research purposes.Comment: Project page: https://www.yusun.work/TRACE/TRACE.htm
Rapid Synthesis of Flavor Compound 4-Ethyloctanoic Acid under Microwave Irradiation
Rapid synthesis of 4-ethyloctanoic acid by means of microwave irradiation is described. Diethyl malonate reacted with 2-ethyl-1-bromohexane in the presence of sodium ethoxide to give diethyl (2-ethylhexyl)malonate (1b). 1b was saponified in the solution of ethanol and potassium hydroxide and then acidified to form (2-ethylhexyl)propanedioic acid (1c), and 1c was heated and decarboxylized to give 4-ethyloctanoic acid (1d). The influence of reaction temperature and reaction time on the yield of 1b and the effect of reaction time on the yield of 1c and 1d were investigated in order to optimize the synthetic conditions. The relative optimal conditions for the synthesis of 1b were a mole ratio of sodium to diethyl malonate to 2-ethylhexyl bromide of 0.1:0.11:0.11, a reaction temperature of 80–85 °C, and a reaction time of 2–2.5 h. The yield of 1b was about 79%. 1b was saponified for 30 min and then acidified to form 1c, and the yield of 1c was 96%. 1c was heated for 16 min at 180°C to give 1d, and the yield of 1d was about 90%. The overall yield of 1d is 70% under microwave irradiation. The reaction time was reduced greatly. In order to compare the result of microwave irradiation with that of an oil bath, the reactions were also performed in an oil bath. The structures of intermediates, product and by-product were confirmed by HRMS, 1H NMR, 13C-NMR and IR
Association of the metabolic score for insulin resistance with cardiovascular diseases, cardiovascular and all-cause mortality in Chinese hypertensive population
ImportanceLittle is known about the relationship between the metabolic score for insulin resistance (METS-IR) and the prognosis of hypertensive patients in China.ObjectiveTo investigate the association between the novel non–insulin‐based METS-IR index and the cardiovascular composite endpoints and all-cause mortality in Chinese hypertensive participants.Design, setting, and participantsThis cohort study used data from the China H-Type Hypertension Project, a long-term prospective cohort consisting of 14234 hypertensive patients in southern China, with a baseline from March to August 2018. The median follow-up period for participants was 3.94 years, as of 2022. The data analysis period is from July 2023 to September 2023.ExposuresMETS-IR index of participants in the Chinese H-type hypertension project. The calculation formula for METS-IR is (Ln (2 × FPG) +TG) × BMI/Ln (HDL-C).Main outcomes and measuresCardiovascular events and cardiovascular, all-cause mortality were identified by linking the cohort database with the health care system through October, 2023.ResultsA total of 14220 participants were included in this study. The prevalence rates of cardiovascular disease (CVD), cardiovascular death, and all-cause death were 2.59% (369/14220), 2.79% (397/14220), and 5.66% (805/14220), respectively. After adjusting for confounding factors in the multivariate logistic regression analysis models, the METS-IR index was significantly positively correlated with CVD, and cardiovascular, all-cause mortality, whether as a categorical or continuous variable. Layered analysis showed that the METS-IR index of hypertensive participants in different subgroups was positively correlated with the endpoint event.Conclusions and relevanceThis large, prospective cohort study demonstrated that the METS-IR index, a new IR evaluation index, were independently associated with a higher risk of the cardiovascular composite endpoint and all-cause mortality among Chinese hypertensive population. Importantly, our finding provides an independent indicator for evaluating the prognosis of hypertensive patients
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Modulating Linker Composition of Haptens Resulted in Improved Immunoassay for Histamine.
Histamine (HA) is an important food contaminant generated during food fermentation or spoilage. However, an immunoassay for direct (derivatization free) determination of HA has rarely been reported due to its small size to induce the desired antibodies by its current hapten-protein conjugates. In this work, despite violating the classical hapten design criteria which recommend introducing a linear aliphatic (phenyl free) linker into the immunizing hapten, a novel haptens, HA-245 designed and synthesized with a phenyl-contained linker, exhibited significantly enhanced immunological properties. Thus, a quality-improved monoclonal antibody (Mab) against HA was elicited by its hapten-carrier conjugates. Then, as the linear aliphatic linker contained haptens, Hapten B was used as linker-heterologous coating haptens to eliminate the recognition of linker antibodies. Indirect competitive ELISA (ic-ELISA) was developed with a 50% inhibition concentration (IC50) of 0.21 mg/L and a limit of detection (LOD) of 0.06 mg/L in buffer solution. The average recoveries of HA from spiked food samples for this ic-ELISA ranged from 84.1% and 108.5%, and the analysis results agreed well with those of referenced LC-MS/MS. This investigation not only realized derivatization-free immunoassay for HA, but also provided a valuable guidance for hapten design and development of immunoassay for small molecules
Computational prediction of novel non-coding RNAs in Arabidopsis thaliana
BackgroundNon-coding RNA (ncRNA) genes do not encode proteins but produce functional RNA molecules that play crucial roles in many key biological processes. Recent genome-wide transcriptional profiling studies using tiling arrays in organisms such as human and Arabidopsis have revealed a great number of transcripts, a large portion of which have little or no capability to encode proteins. This unexpected finding suggests that the currently known repertoire of ncRNAs may only represent a small fraction of ncRNAs of the organisms. Thus, efficient and effective prediction of ncRNAs has become an important task in bioinformatics in recent years. Among the available computational methods, the comparative genomic approach seems to be the most powerful to detect ncRNAs. The recent completion of the sequencing of several major plant genomes has made the approach possible for plants.ResultsWe have developed a pipeline to predict novel ncRNAs in the Arabidopsis (Arabidopsis thaliana) genome. It starts by comparing the expressed intergenic regions of Arabidopsis as provided in two whole-genome high-density oligo-probe arrays from the literature with the intergenic nucleotide sequences of all completely sequenced plant genomes including rice (Oryza sativa), poplar (Populus trichocarpa), grape (Vitis vinifera), and papaya (Carica papaya). By using multiple sequence alignment, a popular ncRNA prediction program (RNAz), wet-bench experimental validation, protein-coding potential analysis, and stringent screening against various ncRNA databases, the pipeline resulted in 16 families of novel ncRNAs (with a total of 21 ncRNAs).ConclusionIn this paper, we undertake a genome-wide search for novel ncRNAs in the genome of Arabidopsis by a comparative genomics approach. The identified novel ncRNAs are evolutionarily conserved between Arabidopsis and other recently sequenced plants, and may conduct interesting novel biological functions
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