1,290 research outputs found

    Asymptotic linearity and limit distributions, approximations.

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    Linear and quadratic forms as well as other low degree polynomials play an important role in statistical inference. Asymptotic results and limit distributions are obtained for a class of statistics depending on m þ X, with X any random vector and m non-random vector with JmJ-þ1. This class contain the polynomials in m þ X. An application to the case of normal X is presented. This application includes a new central limit theorem which is connected with the increase of non-centrality for samples of fixed size. Moreover upper bounds for the suprema of the differences between exact and approximate distributions and their quantiles are obtained

    Differential gene expression profiles of hepatocellular carcinomas associated or not with viral infection

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    Chronic hepatitis B (HBV) and C (HCV) virus infections are the most important factors associated with hepatocellular carcinoma (HCC), but tumor prognosis remains poor due to the lack of diagnostic biomarkers. In order to identify novel diagnostic markers and therapeutic targets, the gene expression profile associated with viral and non-viral HCC was assessed in 9 tumor samples by oligo-microarrays. The differentially expressed genes were examined using a z-score and KEGG pathway for the search of ontological biological processes. We selected a non-redundant set of 15 genes with the lowest P value for clustering samples into three groups using the non-supervised algorithm k-means. Fisher’s linear discriminant analysis was then applied in an exhaustive search of trios of genes that could be used to build classifiers for class distinction. Different transcriptional levels of genes were identified in HCC of different etiologies and from different HCC samples. When comparing HBV-HCC vs HCV-HCC, HBV-HCC/HCV-HCC vs non-viral (NV)-HCC, HBC-HCC vs NV-HCC, and HCV-HCC vs NV-HCC of the 58 non-redundant differentially expressed genes, only 6 genes (IKBKβ, CREBBP, WNT10B, PRDX6, ITGAV, and IFNAR1) were found to be associated with hepatic carcinogenesis. By combining trios, classifiers could be generated, which correctly classified 100% of the samples. This expression profiling may provide a useful tool for research into the pathophysiology of HCC. A detailed understanding of how these distinct genes are involved in molecular pathways is of fundamental importance to the development of effective HCC chemoprevention and treatment

    Random Time-Dependent Quantum Walks

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    We consider the discrete time unitary dynamics given by a quantum walk on the lattice Zd\Z^d performed by a quantum particle with internal degree of freedom, called coin state, according to the following iterated rule: a unitary update of the coin state takes place, followed by a shift on the lattice, conditioned on the coin state of the particle. We study the large time behavior of the quantum mechanical probability distribution of the position observable in Zd\Z^d when the sequence of unitary updates is given by an i.i.d. sequence of random matrices. When averaged over the randomness, this distribution is shown to display a drift proportional to the time and its centered counterpart is shown to display a diffusive behavior with a diffusion matrix we compute. A moderate deviation principle is also proven to hold for the averaged distribution and the limit of the suitably rescaled corresponding characteristic function is shown to satisfy a diffusion equation. A generalization to unitary updates distributed according to a Markov process is also provided. An example of i.i.d. random updates for which the analysis of the distribution can be performed without averaging is worked out. The distribution also displays a deterministic drift proportional to time and its centered counterpart gives rise to a random diffusion matrix whose law we compute. A large deviation principle is shown to hold for this example. We finally show that, in general, the expectation of the random diffusion matrix equals the diffusion matrix of the averaged distribution.Comment: Typos and minor errors corrected. To appear In Communications in Mathematical Physic

    EFICÁCIA DE DOIS SISTEMAS DE TRATAMENTO ANTI-HELMÍNTICO EM FILHOTES DE CÃES COM INFECÇÃO NATURAL

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    O objetivo do presente trabalho foi testar dois esquemas de tratamento para o combate da parasitose gastrintestinal em filhotes de cães recém-desmamados. Foram estabelecidos dois grupos de tratamento, ambos tratados com uma suspensão pamoato de pirantel e oxantel: grupo 1 - quatro desverminações com intervalos de 15 dias e grupo 2 -três desverminações, nos dias 0, 5 e 25 pós desmame. O primeiro tratamento apresentou redução de 98,2 % no número de ovos por grama de fezes (opg) de Toxocara canis, após a primeira desverminação. Cem por cento de redução de opg foi obtido após o segundo tratamento. No tratamento 2, foi obtido um resultado semelhante após três tratamentos. Para ovos de Ancylostoma sp. a formulação mostrou eficácia após a primeira dose para ambos os tratamentos preconizados. Estes resultados indicam que os esquemas de tratamento propostos poderiam ser adotados para combate das infecções por estes parasitas em animais recém-desmamados. Comparison of the efficacy of two systems of antihelminthic treatment in puppies with natural infection Abstract This work was developed to test two treatment outlines for gastrointestinal parasitosis control in weaned puppies. Two treatment groups were established, both treated with oxantel and pyrantel pamoate suspension: group 1 (four doses with 15-days intervals) and group 2 (three doses, at zero, 5th and 25th days). The first treatment presented reduction of 98.2 % on the number of eggs of Toxocara canis per gram of feces (epg) after the first dose. Complete epg reduction was observed after the second treatment, 15 days later. Similar result was obtained after the third dose for the treatment 2. Both treatment protocols showed effectiveness for eggs of Ancylostoma sp. after the first dose. These results indicate that both treatment outlines could be applied for the roundworm and the hookworm control in recently-weaned puppies

    Correlated Markov Quantum Walks

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    We consider the discrete time unitary dynamics given by a quantum walk on Zd\Z^d performed by a particle with internal degree of freedom, called coin state, according to the following iterated rule: a unitary update of the coin state takes place, followed by a shift on the lattice, conditioned on the coin state of the particle. We study the large time behavior of the quantum mechanical probability distribution of the position observable in Zd\Z^d for random updates of the coin states of the following form. The random sequences of unitary updates are given by a site dependent function of a Markov chain in time, with the following properties: on each site, they share the same stationnary Markovian distribution and, for each fixed time, they form a deterministic periodic pattern on the lattice. We prove a Feynman-Kac formula to express the characteristic function of the averaged distribution over the randomness at time nn in terms of the nth power of an operator MM. By analyzing the spectrum of MM, we show that this distribution posesses a drift proportional to the time and its centered counterpart displays a diffusive behavior with a diffusion matrix we compute. Moderate and large deviations principles are also proven to hold for the averaged distribution and the limit of the suitably rescaled corresponding characteristic function is shown to satisfy a diffusion equation. An example of random updates for which the analysis of the distribution can be performed without averaging is worked out. The random distribution displays a deterministic drift proportional to time and its centered counterpart gives rise to a random diffusion matrix whose law we compute. We complete the picture by presenting an uncorrelated example.Comment: 37 pages. arXiv admin note: substantial text overlap with arXiv:1010.400

    Dynamic culturing of cartilage tissue: the significance of hydrostatic pressure

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    Human articular cartilage functions under a wide range of mechanical loads in synovial joints, where hydrostatic pressure (HP) is the prevalent actuating force. We hypothesized that the formation of engineered cartilage can be augmented by applying such physiologic stimuli to chondrogenic cells or stem cells, cultured in hydrogels, using custom-designed HP bioreactors. To test this hypothesis, we investigated the effects of distinct HP regimens on cartilage formation in vitro by either human nasal chondrocytes (HNCs) or human adipose stem cells (hASCs) encapsulated in gellan gum (GG) hydrogels. To this end, we varied the frequency of low HP, by applying pulsatile hydrostatic pressure or a steady hydrostatic pressure load to HNC-GG constructs over a period of 3 weeks, and evaluated their effects on cartilage tissue-engineering outcomes. HNCs (10 · 106 cells/ mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 3 weeks: (1) 0.4MPa Pulsatile HP; (2) 0.4MPa Steady HP; and (3) Static. Subsequently, we applied the pulsatile regimen to hASC-GG constructs and varied the amplitude of loading, by generating both low (0.4 MPa) and physiologic (5 MPa) HP levels. hASCs (10x106 cells/mL) were encapsulated in GG hydrogels (1.5%) and cultured in a chondrogenic medium under three regimens for 4 weeks: (1) 0.4MPa Pulsatile HP; (2) 5MPa Pulsatile HP; and (3) Static. In the HNC study, the best tissue development was achieved by the pulsatile HP regimen, whereas in the hASC study, greater chondrogenic differentiation and matrix deposition were obtained for physiologic loading, as evidenced by gene expression of aggrecan, collagen type II, and sox-9; metachromatic staining of cartilage extracellular matrix; and immunolocalization of collagens. We thus propose that both HNCs and hASCs detect and respond to physical forces, thus resembling joint loading, by enhancing cartilage tissue development in a frequency- and amplitude-dependant manner.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/42316/200

    Integrating whole-genome sequencing in clinical genetics: a novel disruptive structural rearrangement identified in the dystrophin gene (DMD)

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    While in most patients the identification of genetic alterations causing dystrophinopathies is a relatively straightforward task, a significant number require genomic and transcriptomic approaches that go beyond a routine diagnostic set-up. In this work, we present a Becker Muscular Dystrophy patient with elevated creatinine kinase levels, progressive muscle weakness, mild intellectual disability and a muscle biopsy showing dystrophic features and irregular dystrophin labelling. Routine molecular techniques (Southern-blot analysis, multiplex PCR, MLPA and genomic DNA sequencing) failed to detect a defect in the DMD gene. Muscle DMD transcript analysis (RT-PCR and cDNA-MLPA) showed the absence of exons 75 to 79, seen to be present at the genomic level. These results prompted the application of low-coverage linked-read whole-genome sequencing (WGS), revealing a possible rearrangement involving DMD intron 74 and a region located upstream of the PRDX4 gene. Breakpoint PCR and Sanger sequencing confirmed the presence of a ~8 Mb genomic inversion. Aberrant DMD transcripts were subsequently identified, some of which contained segments from the region upstream of PRDX4. Besides expanding the mutational spectrum of the disorder, this study reinforces the importance of transcript analysis in the diagnosis of dystrophinopathies and shows how WGS has a legitimate role in clinical laboratory genetics.Molecular Technology and Informatics for Personalised Medicine and Healt

    Gravitational Collapse in Generalized Vaidya Space-Time for Lovelock Gravity Theory

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    In this work, we have assumed the generalized Vaidya solution in Lovelock theory of gravity in (n+2)(n+2)-dimensions. It has been shown that Gauss-Bonnet gravity, dimensionally continued Lovelock gravity and pure Lovelock gravity can be constructed by suitable choice of parameters. We have investigated the occurrence of singularities formed by the gravitational collapse in above three particular forms of Lovelock theory of gravity. The dependence of the nature of singularity on the existence of radial null geodesic for Vaidya space-time has been specially considered. In all the three models, we have shown that the nature of singularities (naked singularity or black hole) completely depend on the parameters. Choices of various parameters are shown in tabular form. In Gauss-Bonnet gravity theory, it can be concluded that the possibility of naked singularity increases with increase in dimensions. In dimensionally continued Lovelock gravity, the naked singularity is possible for odd dimensions for several values of parameters. In pure Lovelock gravity, only black hole forms due to the gravitational collapse for any values of parameters. It has been shown that when accretion is taking place on a collapsing object, it is highly unlikely to get a black hole. Finally on considering the phantom era in the expanding universe it is observed that there is no possibility of formation of a black hole if we are in the Gauss-Bonnet gravity considering the accreting procedure upon a collapsing object.Comment: 11 page
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