186,393 research outputs found

    ON THE SHORT DISTANCE BEHAVIOR OF STRING THEORIES

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    Short distance behavior of string theories is investigated by the use of the discretized path-integral formulation. In particular, the minimum physical length and the generalized uncertainty relation are re-derived from a set of Ward-Takahashi identities. Several issues related to the form of the generalized uncertainty relation and to its implications are discussed. A consistent qualitative picture of short distance behavior of string theory seems to emerge from such a study

    La ricomposizione territoriale dal XII al XIII secolo

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    Testo per un capitolo dell'Atlante Storico TreccaniTexts for the Treccani Historical Atla

    Identification of candidate regulatory sequences in mammalian 3' UTRs by statistical analysis of oligonucleotide distributions

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    Abstract Background 3' untranslated regions (3' UTRs) contain binding sites for many regulatory elements, and in particular for microRNAs (miRNAs). The importance of miRNA-mediated post-transcriptional regulation has become increasingly clear in the last few years. Results We propose two complementary approaches to the statistical analysis of oligonucleotide frequencies in mammalian 3' UTRs aimed at the identification of candidate binding sites for regulatory elements. The first method is based on the identification of sets of genes characterized by evolutionarily conserved overrepresentation of an oligonucleotide. The second method is based on the identification of oligonucleotides showing statistically significant strand asymmetry in their distribution in 3' UTRs. Conclusion Both methods are able to identify many previously known binding sites located in 3'UTRs, and in particular seed regions of known miRNAs. Many new candidates are proposed for experimental verification.</p

    The My Active and Healthy Aging ICT platform prevents quality of life decline in older adults: a randomised controlled study

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    Introduction: Prevention of frailty is paramount in older adults. We evaluated the efficacy of a tailored multidomain intervention, monitored with the My Active and Healthy Aging platform, in reducing conversion from a prefrail status to overt frailty and preventing decline in quality of life.Methods: We performed a multicentre, multicultural, randomised control study. The effects of multidomain interventions on frailty parameters, quality of life, physical, cognitive, psychosocial function, nutrition and sleep were evaluated in a group of 101 prefrail older subjects and compared with 100 prefrail controls, receiving general health advice.Results: At the 12-month assessment, controls showed a decline in quality of life that was absent in the active group. In addition, active participants showed an increase in mood and nutrition function. No effect on remaining parameter was observed.Discussion: Our study supports the use of personalised multidomain intervention, monitored with an information and communication technology platform, in preventing quality of life decline in older adults.Members of The My-AHA Consortium: A. E. Vercelli, I. Rainero, M. Caglio, C. Carbone, E. Rubino, A. Vacca and P. Provero (University of Torino, Italy); M. J. Summers (University of the Sunshine Coast, Australia); M. Monter (Gestio Socio Sanitaria al Mediterrani, Spain); D. Burin and R. Kawashima (Tohoku University, Japan); E. Giannouli and W. Zijlstra (German Sport University, Cologne, Germany); S. Alonso, S. Schnieder, S. D. Roelen, L. Kachele and J. Krajewski (Institut fur Experimentelle Psychophysiologie GmbH, Germany); H. de Rosario, J. Laparra, J. F. Serrano, E. Medina, A. Lopez, J. F. Pedrero and U. Martınez (Instituto de Biomecanica Valencia, Spain); M. Bazzani and A. Frisello (LINKS Foundation, Torino, Italy); G. Aumayr, G. Ringler, S. Kirilova, G. Salomon, V. Simanko and N. Sturm (Johanniter Osterreich Ausbildung und Forschung Gemeinnutzige, Austria); N. Kaartinen and A. Kern (KAASA Solution); S. Bandelow and N. G. Niederstrasser (Loughborough University, UK); D. Vaziri, A. Tabatabaei and L. Ciferri (International University of Japan, Japan)

    Ab initio identification of putative human transcription factor binding sites by comparative genomics

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    Abstract Background Understanding transcriptional regulation of gene expression is one of the greatest challenges of modern molecular biology. A central role in this mechanism is played by transcription factors, which typically bind to specific, short DNA sequence motifs usually located in the upstream region of the regulated genes. We discuss here a simple and powerful approach for the ab initio identification of these cis-regulatory motifs. The method we present integrates several elements: human-mouse comparison, statistical analysis of genomic sequences and the concept of coregulation. We apply it to a complete scan of the human genome. Results By using the catalogue of conserved upstream sequences collected in the CORG database we construct sets of genes sharing the same overrepresented motif (short DNA sequence) in their upstream regions both in human and in mouse. We perform this construction for all possible motifs from 5 to 8 nucleotides in length and then filter the resulting sets looking for two types of evidence of coregulation: first, we analyze the Gene Ontology annotation of the genes in the set, searching for statistically significant common annotations; second, we analyze the expression profiles of the genes in the set as measured by microarray experiments, searching for evidence of coexpression. The sets which pass one or both filters are conjectured to contain a significant fraction of coregulated genes, and the upstream motifs characterizing the sets are thus good candidates to be the binding sites of the TF's involved in such regulation. In this way we find various known motifs and also some new candidate binding sites. Conclusion We have discussed a new integrated algorithm for the "ab initio" identification of transcription factor binding sites in the human genome. The method is based on three ingredients: comparative genomics, overrepresentation, different types of coregulation. The method is applied to a full-scan of the human genome, giving satisfactory results.</p

    Optic nerve sheath diameter asymmetry in healthy subjects and patients with intracranial hypertension

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    Ultrasonography of the optic nerve sheath diameter (ONSD) is used for the non-invasive assessment of increased intracranial pressure (ICP). ONSD values are usually obtained by averaging the measurements of the two eyes, but asymmetric ONSD dilation is possible, leading to potentially inaccurate ICP estimation when using binocular averaging. In addition, few data are available about the asymmetry of the ONSD and the use of the maximum ONSD value between eyes for raised ICP detection. The aim of the study was to evaluate the interocular ONSD asymmetry in healthy subjects and patients with intracranial hypertension (IH) by ultrasonography and to investigate whether the maximum ONSD could be as useful as the binocular assessment

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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