19,898 research outputs found
Statistical Mesoscopic Hydro-Thermodynamics: The Description of Kinetics and Hydrodynamics of Nonequilibrium Processes in Single Liquids
Hydrodynamics, a term apparently introduced by Daniel Bernoulli (1700-1783)
to comprise hydrostatic and hydraulics, has a long history with several
theoretical approaches. Here, after a descriptive introduction, we present
so-called mesoscopic hydro-thermodynamics, which is also referred to as
higher-order generalized hydrodynamics, built within the framework of a
mechanical-statistical formalism. It consists of a description of the material
and heat motion of fluids in terms of the corresponding densities and their
associated fluxes of all orders. In this way, movements are characterized in
terms of intermediate to short wavelengths and intermediate to high
frequencies. The fluxes have associated Maxwell-like times, which play an
important role in determining the appropriate contraction of the description
(of the enormous set of fluxes of all orders) necessary to address the
characterization of the motion in each experimental setup. This study is an
extension of a preliminary article: Physical Review E \textbf{91}, 063011
(2015)
Regression analysis with missing data and unknown colored noise: application to the MICROSCOPE space mission
The analysis of physical measurements often copes with highly correlated
noises and interruptions caused by outliers, saturation events or transmission
losses. We assess the impact of missing data on the performance of linear
regression analysis involving the fit of modeled or measured time series. We
show that data gaps can significantly alter the precision of the regression
parameter estimation in the presence of colored noise, due to the frequency
leakage of the noise power. We present a regression method which cancels this
effect and estimates the parameters of interest with a precision comparable to
the complete data case, even if the noise power spectral density (PSD) is not
known a priori. The method is based on an autoregressive (AR) fit of the noise,
which allows us to build an approximate generalized least squares estimator
approaching the minimal variance bound. The method, which can be applied to any
similar data processing, is tested on simulated measurements of the MICROSCOPE
space mission, whose goal is to test the Weak Equivalence Principle (WEP) with
a precision of . In this particular context the signal of interest is
the WEP violation signal expected to be found around a well defined frequency.
We test our method with different gap patterns and noise of known PSD and find
that the results agree with the mission requirements, decreasing the
uncertainty by a factor 60 with respect to ordinary least squares methods. We
show that it also provides a test of significance to assess the uncertainty of
the measurement.Comment: 12 pages, 4 figures, to be published in Phys. Rev.
Lateral Casimir force beyond the Proximity Force Approximation
We argue that the appropriate variable to study a non trivial geometry
dependence of the Casimir force is the lateral component of the Casimir force,
which we evaluate between two corrugated metallic plates outside the validity
of the Proximity Force Approximation (PFA). The metallic plates are described
by the plasma model, with arbitrary values for the plasma wavelength, the plate
separation and the corrugation period, the corrugation amplitude remaining the
smallest length scale. Our analysis shows that in realistic experimental
situations the Proximity Force Approximation overestimates the force by up to
30%.Comment: 4 pages. Identical to v1, which was accidentally replaced by a
different paper (quant-ph/0610026
Minimal PD-sets for codes associated with the graphs Qm2, m even
Please read abstract in the article.The National Research Foundation of South Africahttp://link.springer.com/journal/2002021-12-08hj2021Mathematics and Applied Mathematic
Pesquisa e desenvolvimento para aproveitamento da torta de pinhão-manso na alimentação animal.
O pinhão manso A torta de pinhão manso Tratamentos fÃsico- quÃmicos da torta de pinhão-manso Tratamento FÃsico- quÃmicos da torta de pinhão-manso Tratamento microbiano da torta de pinhão-manso Melhoramento microbiano da torta de pinhão-manso Melhoramento genético para cultivares com baixos teores de ésteres de forbol Digestibilidade da torta tóxica de pinhão-manso Perspectivas.bitstream/item/61930/1/Folder-destoxificacao-pinhao-manso-2012.pd
Energy metabolism in human pluripotent stem cells and their differentiated counterparts
Background: Human pluripotent stem cells have the ability to generate all cell types present in the adult organism, therefore harboring great potential for the in vitro study of differentiation and for the development of cell-based therapies. Nonetheless their use may prove challenging as incomplete differentiation of these cells might lead to tumoregenicity. Interestingly, many cancer types have been reported to display metabolic modifications with features that might be similar to stem cells. Understanding the metabolic properties of human pluripotent stem cells when compared to their differentiated counterparts can thus be of crucial importance. Furthermore recent data has stressed distinct features of different human pluripotent cells lines, namely when comparing embryo-derived human embryonic stem cells (hESCs) and induced pluripotent stem cells (IPSCs) reprogrammed from somatic cells. Methodology/Principal Findings: We compared the energy metabolism of hESCs, IPSCs, and their somatic counterparts. Focusing on mitochondria, we tracked organelle localization and morphology. Furthermore we performed gene expression analysis of several pathways related to the glucose metabolism, including glycolysis, the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle. In addition we determined oxygen consumption rates (OCR) using a metabolic extracellular flux analyzer, as well as total intracellular ATP levels by high performance liquid chromatography (HPLC). Finally we explored the expression of key proteins involved in the regulation of glucose metabolism. Conclusions/Findings: Our results demonstrate that, although the metabolic signature of IPSCs is not identical to that of hESCs, nonetheless they cluster with hESCs rather than with their somatic counterparts. ATP levels, lactate production and OCR revealed that human pluripotent cells rely mostly on glycolysis to meet their energy demands. Furthermore, our work points to some of the strategies which human pluripotent stem cells may use to maintain high glycolytic rates, such as high levels of hexokinase II and inactive pyruvate dehydrogenase (PDH). © 2011 Varum et al
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