450 research outputs found

    Internal energy fluctuations of a granular gas under steady uniform shear flow

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    The stochastic properties of the total internal energy of a dilute granular gas in the steady uniform shear flow state are investigated. A recent theory formulated for fluctuations about the homogeneous cooling state is extended by analogy with molecular systems. The theoretical predictions are compared with molecular dynamics simulation results. Good agreement is found in the limit of weak inelasticity, while systematic and relevant discrepancies are observed when the inelasticity increases. The origin of this behavior is discussed

    Rheological effects in the linear response and spontaneous fluctuations of a sheared granular gas

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    The decay of a small homogeneous perturbation of the temperature of a dilute granular gas in the steady uniform shear flow state is investigated. Using kinetic theory based on the inelastic Boltzmann equation, a closed equation for the decay of the perturbation is derived. The equation involves the generalized shear viscosity of the gas in the time-dependent shear flow state, and therefore it predicts relevant rheological effects beyond the quasi-elastic limit. A good agreement is found when comparing the theory with molecular dynamics simulation results. Moreover, the Onsager postulate on the regression of fluctuations is fulfilled

    Mesoscopic Theory of Critical Fluctuations in Isolated Granular Gases

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    Fluctuating hydrodynamics is used to describe the total energy fluctuations of a freely evolving gas of inelastic hard spheres near the threshold of the clustering instability. They are shown to be governed by vorticity fluctuations only, that also lead to a renormalization of the average total energy. The theory predicts a power-law divergent behavior of the scaled second moment of the fluctuations, and a scaling property of their probability distribution, both in agreement with simulations results. A more quantitative comparison between theory and simulation for the critical amplitudes and the form of the scaling function is also carried out

    Universal reference state in a driven homogeneous granular gas

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    We study the dynamics of a homogeneous granular gas heated by a stochastic thermostat, in the low density limit. It is found that, before reaching the stationary regime, the system quickly "forgets" the initial condition and then evolves through a universal state that does not only depend on the dimensionless velocity, but also on the instantaneous temperature, suitably renormalized by its steady state value. We find excellent agreement between the theoretical predictions at Boltzmann equation level for the one-particle distribution function, and Direct Monte Carlo simulations. We conclude that at variance with the homogeneous cooling phenomenology, the velocity statistics should not be envisioned as a single-parameter, but as a two-parameter scaling form, keeping track of the distance to stationarity

    Hydrodynamic description for ballistic annihilation systems

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    The problem of the validity of a hydrodynamic description for a system in which there are no collisional invariants is addressed. Hydrodynamic equations have been derived and successfully tested against simulation data for a system where particles annihilate with a probability p, or collide elastically otherwise. The response of the system to a linear perturbation is analyzed as well

    Food intake biomarkers for berries and grapes

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    Grapes and berries are two types of widely consumed fruits characterized by a high content in different phytochemicals. However, their accurate dietary assessment is particularly arduous, because of the already wide recognized bias associated with self-reporting methods, combined with the large range of species and cultivars and the fact that these fruits are popularly consumed not only in fresh and frozen forms but also as processed and derived products, including dried and canned fruits, beverages, jams, and jellies. Reporting precise type and/or quantity of grape and berries in FFQ or diaries can obviously be affected by errors. Recently, biomarkers of food intake (BFIs) rose as a promising tool to provide accurate information indicating consumption of certain food items. Protocols for performing systematic reviews in this field, as well as for assessing the validity of candidate BFIs have been developed within the Food Biomarker Alliance (FoodBAll) Project. This paper aims to evaluate the putative BIFs for blueberries, strawberries, raspberries, blackberries, cranberries, blackcurrant, and grapes. Candidate BFIs for grapes were resveratrol metabolites and tartaric acid. The metabolites considered as putative BFI for berries consumption were mostly anthocyanins derivatives together with several metabolites of ellagitannins and some aroma compounds. However, identification of BFIs for single berry types encountered more difficulties. In the absence of highly specific metabolites reported to date, we suggested some multi-metabolite panels that may be further investigated as putative biomarkers for some berry fruits

    Combined application of polyacrylate scaffold and lipoic acid treatment promotes neural tissue reparation after brain injury

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    [EN] Primary objective: The aim of this study was to investigate the reparative potential of a polymeric scaffold designed for brain tissue repair in combination with lipoic acid. Research design: Histological, cytological and structural analysis of a combined treatment after a brain cryo-injury model in rats. Methods and procedures: Adult Wistar rats were subjected to cryogenic brain injury. A channelled-porous scaffold of ethyl acrylate and hydroxyethylacrylate, p(EA-co-HEA) was grafted into cerebral penumbra alone or combined with intraperitoneal LA administration. Histological and cytological evaluation was performed after 15 and 60 days and structural magnetic resonance (MRI) assessment was performed at 2 and 6 months after the surgery. Main outcomes and results: The scaffold was suitable for the establishment of different cellular types. The results obtained suggest that this strategy promotes blood vessels formation, decreased microglial response and neuron migration, particularly when LA was administrated. Conclusions: These evidences demonstrated that the combination of a channelled polymer scaffold with LA administration may represent a potential treatment for neural tissue repair after brain injury.The authors report no conflicts of interest. JMSL acknowledges funding through Programa de Ayudas a la Investigación Científica Universidad CEU-Cardenal Herrera (PRCEU-UCH 34/12), PRCEU-UCH 38/10 and programa ayudas a grupos consolidados 2014-15). CMR and MMP acknowledge financing through projects MAT2011-28791-C03-02 and ERA-NET NEURON project PRI-PIMNEU-2011-1372.Rocamonde, B.; Paradells, S.; Garcia Esparza, MA.; Sanchez Vives, M.; Sauro, S.; Martínez-Ramos, C.; Monleón Pradas, M.... (2016). Combined application of polyacrylate scaffold and lipoic acid treatment promotes neural tissue reparation after brain injury. 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    Drug Repurposing for Cancers With Limited Survival: Protocol for a Retrospective Cohort Study

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    Only 5% of the molecules tested in oncology phase 1 trials reach the market after an average of 7.5 years of waiting and at a cost of tens of millions of dollars. To reduce the cost and shorten the time of discovery of new treatments, drug repurposing (research with molecules already approved for another indication) and the use of secondary data (not collected for the purpose of research) have been proposed. Due to advances in informatics in clinical care, secondary data can, in some cases, be of equal quality to primary data generated through prospective studies.Objective: The objective of this study is to identify drugs currently marketed for other indications that may have an effect on the prognosis of patients with cancer.Methods: We plan to monitor a cohort of patients with high-lethality cancers treated in the public health system of Catalonia between 2006 and 2012, retrospectively, for survival for 5 years after diagnosis or until death. A control cohort, comprising people without cancer, will also be retrospectively monitored for 5 years. The following study variables will be extracted from different population databases: type of cancer (patients with cancer cohort), date and cause of death, pharmacological treatment, sex, age, and place of residence. During the first stage of statistical analysis of the patients with cancer cohort, the drugs consumed by the long-term survivors (alive at 5 years) will be compared with those consumed by nonsurvivors. In the second stage, the survival associated with the consumption of each relevant drug will be analyzed. For the analyses, groups will be matched for potentially confounding variables, and multivariate analyses will be performed to adjust for residual confounding variables if necessary. The control cohort will be used to verify whether the associations found are exclusive to patients with cancer or whether they also occur in patients without cancer.Results: We anticipate discovering multiple significant associations between commonly used drugs and the survival outcomes of patients with cancer. We expect to publish the initial results in the first half of 2024.Conclusions: This retrospective study may identify several commonly used drugs as candidates for repurposing in the treatment of various cancers. All analyses are considered exploratory; therefore, the results will have to be confirmed in subsequent clinical trials. However, the results of this study may accelerate drug discovery in oncology

    Origin of the X-ray Emission in the Nuclei of FR Is

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    We investigate the X-ray origin in FRIs using the multi-waveband high resolution data of eight FR I sources, which have very low Eddington ratios. We fit their multi-waveband spectrum using a coupled accretion-jet model. We find that X-ray emission in the source with the highest L_X (~1.8*10^-4 L_Edd) is from the advection-dominated accretion flow (ADAF). Four sources with moderate L_X(~several*10^-6 L_Edd) are complicated. The X-ray emission of one FR I is from the jet, and the other three is from the sum of the jet and ADAF. The X-ray emission in the three least luminous sources (L_X<1.0*10^-6L_Edd) is dominated by the jet. These results roughly support the predictions of Yuan and Cui(2005) where they predict that when the X-ray luminosity of the system is below a critical value, the X-radiation will not be dominated by the emission from the ADAF any longer, but by the jet. We also find that the accretion rates in four sources must be higher than the Bondi rates, which implies that other fuel supply (e.g., stellar winds) inside the Bondi radius should be important.Comment: 6 pages. To published in Journal of Physics, in proceedings of "The Universe under the Microscope - Astrophysics at High Angular Resolution" (Bad Honnef, Germany, April 2008), eds. R. Schoedel, A. Eckart, S. Pfalzner, and E. Ro
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