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Search Results: 1 - 10 of 32672 matches for " Peter Valent "
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Six Categories of Illnesses  [PDF]
Paul Valent
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.47082
Abstract:

Studies show that between 40% and 60% of patients attending emergency departments have medically unexplained physical symptoms (MUPS) that are determined by psychosocial factors. However, there exists no clear categorization of these factors and the symptoms that they produce. This paper delineates six categories of illnesses that help to overcome this deficit. The categories of illnesses are 1) Typical physical illnesses; 2) Typical psychiatric illnesses; 3) Psychophysiological symptoms; 4) Symptoms associated with reliving traumas; 5) “Cherished” or hysterical symptoms; 6) Symptoms that identify with illnesses of others. Clinical examples of each category are provided.

-fuzzy compactness in -topological spaces
Valentín Gregori,Hans-peter A. Künzi
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s0161171203204233
Abstract: Using a gradation of openness in a (Chang fuzzy) I-topological space, we introduce degrees of compactness that we call α-fuzzy compactness (where α belongs to the unit interval), so extending the concept of compactness due to C. L. Chang. We obtain a Baire category theorem for α-locally compact spaces and construct a one-point α-fuzzy compactification of an I-topological space.
Analysis of Nitrate Concentrations Using Nonlinear Time Series Models
Peter Valent, Nicholas J. K. Howden, Ján Szolgay, Magda Komorníková
Journal of Hydrology and Hydromechanics , 2011, DOI: 10.2478/v10098-011-0013-9
Abstract: This study examines two long-term time series of nitrate-nitrogen concentrations from the River Ouse and Stour situated in the Eastern England. The time series of monthly averages were decomposed into trend, seasonal and cyclical components and residuals to create a simple additive model. Residuals were then modelled by linear time series models represented by models of the ARMA (autoregressive moving average) class and nonlinear time series models with multiple regimes represented by SETAR (self-exciting threshold autoregressive) and MSW (Markov switching) models. The analysis showed that, based on the minimal value of residual sum of squares (RSS) of one-step ahead forecast in both datasets, SETAR and MSW models described the time series better than models ARMA. However, the relative improvement of SETAR models against ARMA models was low ranging between 1% and 4% with the exception of the three-regime model for the River Stour where the improvement was 48.9%. In comparison, the relative improvement of MSW models was between 44.6% and 52.5 for two-regime and from 60.4% to 75% for three-regime models. However, the visual assessment of models plotted against original datasets showed that despite a high value of RSS, some ARMA models could describe the analyzed time series better than AR (autoregressive), MA (moving average) and SETAR models with lower values of RSS. In both datasets MSW models provided a very good visual fit describing most of the extreme values. The results of this work could be used as a base for construction of other time series models used to describe or predict nitrate-nitrogen concentrations.
The Transcription Factor MAZR Preferentially Acts as a Transcriptional Repressor in Mast Cells and Plays a Minor Role in the Regulation of Effector Functions in Response to FcεRI Stimulation
Anastasia Abramova, Shinya Sakaguchi, Alexandra Schebesta, Hammad Hassan, Nicole Boucheron, Peter Valent, Axel Roers, Wilfried Ellmeier
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077677
Abstract: Mast cells are key players in type I hypersensitivity reactions in humans and mice and their activity has to be tightly controlled. Previous studies implicated the transcription factor MAZR in the regulation of mast cell function. To study the role of MAZR in mast cells, we generated a conditional Mazr allele and crossed MazrF/F mice with the Vav-iCre deleter strain, which is active in all hematopoietic cells. MAZR-null BM-derived mast cells (BMMC) were phenotypically indistinguishable from wild-type BMMCs, although the numbers of IL-3 generated MazrF/FVav-iCre BMMCs were reduced in comparison to MazrF/F BMMCs, showing that MAZR is required for the efficient generation of BMMC in vitro. A gene expression analysis revealed that MAZR-deficiency resulted in the dysregulation of 128 genes, with more genes up- than down-regulated in the absence of MAZR, indicating that MAZR acts as a transcriptional repressor in mast cells. Among the up-regulated genes were the chemokines Ccl5, Cxcl10, Cxcl12, the chemokine receptor Ccr5 and the cytokine IL18, suggesting an immunoregulatory role for MAZR in mast cells. Enforced expression of MAZR in mature Mazr-deficient BMMCs rescued the altered expression pattern of some genes tested, suggesting direct regulation of these genes by MAZR. Upon FcεRI stimulation, Mazr expression was transiently down-regulated in BMMCs. However, early and late effector functions in response to FcεRI-mediated stimulation were not impaired in the absence of MAZR, with the exception of IL-6, which was slightly decreased. Taken together, out data indicate that MAZR preferentially acts as a transcriptional repressor in mast cells, however MAZR plays only a minor role in the transcriptional networks that regulate early and late effector functions in mast cells in response to FcεRI stimulation.
E- and P-Selectins Are Essential for Repopulation of Chronic Myelogenous and Chronic Eosinophilic Leukemias in a Scid Mouse Xenograft Model
Daniel Wicklein, Anna Schmidt, Vera Labitzky, Sebastian Ullrich, Peter Valent, Udo Schumacher
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070139
Abstract: In chronic myelogenous (CML) and chronic eosinophilic leukemia (CEL), neoplastic cells spread via the circulation into various extramedullary organs. As E- and P-selectin constitute the starting point for the leucocyte adhesion/invasion cascade, and CEL and CML cells share many properties with normal granulocytes, we investigated the role of these selectins in CEL and CML cell expansion and organ invasion in a xenotransplantation model using scid mice. Using two human leukemic cell lines (EOL-1 and K562), we were able to show that E- and P-selectins mediate leukemia cell tethering and adherence in a laminar flow assay. While E-selectin binding depended on sialylated carbohydrate moieties, P-selectin binding was completely (K562) or partially (EOL-1) independent of these carbohydrates indicating the involvement of non-canonical selectin ligands. In a xenograft model in scid mice, both cell lines invaded the bone marrow and other organs, formed chloromas, and ultimately produced an overt leukemia. In contrast, in E- and P-selectin knockout scid mice, the cells failed to show engraftment in 8 out of 10 animals and even if they did engraft, they produced only little organ invasion and chloroma formation. Together, these data suggest that E- and P-selectins play an important role in leukemic dissemination in CML and CEL.
Time continuum and true long-term ecology: from theory to practice
Valentí Rull
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00075
Abstract: The need for long-term studies to understand ecological dynamics is widely recognized but has not been satisfactorily addressed to date. The development of “long-term” (LT) observatories has aimed to improve the situation, but the main handicaps are that we should wait for generations to yield reliable results and that a number of ecological processes occurring at time scales larger than centuries will not be fully resolved. Palaeoecology can provide the needed time scale for true long-term ecology, but it is limited by the ability to merge ecological, and palaeoecological data into continuous time series. This paper suggests a practical way of attaining such goals based on the concept of time continuum. A short review is provided on the main handicaps for palaeoecological records to be incorporated into current ecological datasets and the recent improvements in the field. A global network of past-present-future ecological observatories (PPFEO) centered around lakes with annually-laminated sediments could act as a means of producing truly long-term and continuous ecological records by combining high-resolution palaeoecological techniques with ecological methods commonly used in LT observatories.
Bianchi type II,III and V diagonal Einstein metrics re-visited
Galliano Valent
Physics , 2010, DOI: 10.1007/s10714-009-0774-1
Abstract: We present, for both minkowskian and euclidean signatures, short derivations of the diagonal Einstein metrics for Bianchi type II, III and V. For the first two cases we show the integrability of the geodesic flow while for the third case a somewhat unusual bifurcation phenomenon takes place: for minkowskian signature elliptic functions are essential in the metric while for euclidean signature only elementary functions appear.
Explicit integrable systems on two dimensional manifolds with a cubic first integral
Galliano Valent
Physics , 2010,
Abstract: A few years ago Selivanova gave an existence proof for some integrable models, in fact geodesic flows on two dimensional manifolds, with a cubic first integral. However the explicit form of these models hinged on the solution of a nonlinear third order ordinary differential equation which could not be obtained. We show that an appropriate choice of coordinates allows for integration and gives the explicit local form for the full family of integrable systems. The relevant metrics are described by a finite number of parameters and lead to a large class of models on the manifolds ${\mb S}^2, {\mb H}^2$ and $P^2({\mb R})$ containing as special cases examples due to Goryachev, Chaplygin, Dullin, Matveev and Tsiganov.
Bianchi III and V Einstein metrics
Galliano Valent
Physics , 2008,
Abstract: We present diagonal Einstein metrics for Bianchi III and V, both for minkowskian and euclidean signatures and we show that the Einstein Bianchi III metrics have an integrable geodesic flow.
Higher Conservation Law for the Multi-Centre Metrics
G. Valent
Physics , 2002,
Abstract: The multi-centre metrics are a family of euclidean solutions of the empty space Einstein equations with self-dual curvature. For this full class, we determine which metrics do exhibit an extra conserved quantity quadraic in the momenta, induced by a Killing-Stackel tensor. Our results bring to light several metrics which correspond to classically integrable dynamical systems. They include, as particular cases, the Eguchi-Hanson and Taub-NUT metrics.
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