2,543 research outputs found
A Video Bioinformatics Method to Quantify Cell Spreading and Its Application to Cells Treated with Rho-Associated Protein Kinase and Blebbistatin
Commercial software is available for performing video bioinformatics analysis on cultured cells. Such software is convenient and can often be used to create suitable protocols for quantitative analysis of video
data with relatively little background in image processing. This chapter demonstrates that CL-Quant software, a commercial program produced by DRVision, can be used to automatically analyze cell spreading in time-lapse videos of human embryonic stem cells (hESC). Two cell spreading protocols were developed and tested. One was professionally created by engineers at DRVision and adapted to this project. The other was created by an undergraduate student with 1 month of experience using CL-Quant.
Both protocols successfully segmented small spreading colonies of hESC, and, in general, were in good agreement with the ground truth which was measured using ImageJ. Overall the professional protocol
performed better segmentation, while the user-generated protocol demonstrated that someone who had relatively little background with CL-Quant can successfully create protocols. The protocols were applied to
hESC that had been treated with ROCK inhibitors or blebbistatin, which tend to cause rapid attachment and spreading of hESC colonies. All treatments enabled hESC to attach rapidly. Cells treated with the
ROCK inhibitors or blebbistatin spread more than controls and often looked stressed. The use of the spreading analysis protocol can provide a very rapid method to evaluate the cytotoxicity of chemical treatment and reveal effects on the cytoskeleton of the cell. While hESC are presented in this chapter, other cell types could also be used in conjunction with the spreading protocol
MATEX: A Distributed Framework for Transient Simulation of Power Distribution Networks
We proposed MATEX, a distributed framework for transient simulation of power
distribution networks (PDNs). MATEX utilizes matrix exponential kernel with
Krylov subspace approximations to solve differential equations of linear
circuit. First, the whole simulation task is divided into subtasks based on
decompositions of current sources, in order to reduce the computational
overheads. Then these subtasks are distributed to different computing nodes and
processed in parallel. Within each node, after the matrix factorization at the
beginning of simulation, the adaptive time stepping solver is performed without
extra matrix re-factorizations. MATEX overcomes the stiff-ness hinder of
previous matrix exponential-based circuit simulator by rational Krylov subspace
method, which leads to larger step sizes with smaller dimensions of Krylov
subspace bases and highly accelerates the whole computation. MATEX outperforms
both traditional fixed and adaptive time stepping methods, e.g., achieving
around 13X over the trapezoidal framework with fixed time step for the IBM
power grid benchmarks.Comment: ACM/IEEE DAC 2014. arXiv admin note: substantial text overlap with
arXiv:1505.0669
Optimal group testing designs for estimating prevalence with uncertain testing errors
We construct optimal designs for group testing experiments where the goal is
to estimate the prevalence of a trait by using a test with uncertain
sensitivity and specificity. Using optimal design theory for approximate
designs, we show that the most efficient design for simultaneously estimating
the prevalence, sensitivity and specificity requires three different group
sizes with equal frequencies. However, if estimating prevalence as accurately
as possible is the only focus, the optimal strategy is to have three group
sizes with unequal frequencies. On the basis of a chlamydia study in the
U.S.A., we compare performances of competing designs and provide insights into
how the unknown sensitivity and specificity of the test affect the performance
of the prevalence estimator. We demonstrate that the locally D- and Ds-optimal
designs proposed have high efficiencies even when the prespecified values of
the parameters are moderately misspecified
Análise da influência da liquidez e endividamento sobre o retorno financeiro das empresas em período de crise
A crise causada pela pandemia da COVID-19 trouxe desafios enormes para as empresas em geral. O desbalanceamento da oferta e da demanda, incertezas com interrupções e retomadas na economia demandaram a capacidade de gerenciamento de caixa e obrigações financeiras. Nesse cenário, este artigo buscou avaliar se as condições de liquidez e endividamento iniciais são determinantes para os resultados obtidos em períodos de estresse econômico. Foi analisada uma amostra de empresas do setor automotivo listadas na bolsa de valores e seus indicadores de liquidez, endividamento e rentabilidade do período entre 2018 e 2020. Os resultados foram inconclusivos quanto à influência direta dos dois elementos (liquidez e endividamento) no resultado final das empresas. O aumento das margens, obtido através da diluição dos custos por crescimento de receitas, apresenta uma influência maior na variação da rentabilidade
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