930 resultados para Theta Tau
Resumo:
Purpose: The Quality of life is currently a major topic discussed in our society. The World Health Organization (WHO) has been developing a unifying and transcultural definition of QOL. They considered it as 'the individual's perception of his or her position in life, within the cultural context and value system he or she lives in, and in relation to his or her goals, expectations, parameters and social relations. It is a broad ranging concept affected in a complex way by the person's physical health, psychological state, level of independence, social relationships and their relationship to salient features of their environment (WHOQOL, 1997, p. 1). Congenital heart disease is the most prevalent congenital disease in Portugal. Despite the advances in cardiac treatment and an early correct diagnosis that could increase the survival of children with congenital heart disease, this condition influences the quality of life of children, adolescents and their parents. Knowing the perception of quality of life could help healthcare professionals, nurses in particular, providing suited care to the needs of these families, establishing priorities in their interventions, sensing predictors of a poor quality of life, promoting adherence to treatment and boosting compliance with treatment, and fostering greater satisfaction for these children, adolescents and their parents. 'As part of broader research and with the awareness that the chronic conditions could impact the quality of life and considering that all advances on treating congenital cardiac diseases we have defined this main objective: To determine the quality of life in children and adolescents with congenital heart disease (CHD) and the perception of their parents, as well as factors that influence it. Methods: It is a quantitative, descriptive and correlational research. The data collection tool was a questionnaire, which consisted of four parts: socio-demographic and educational characteristics, clinical characteristics, and quality of life, obtained using the Pediatric Cardiac Quality of Life Inventory ? PCQLI - (Marino, Tomlinson, Wernovsky, Drotar , Newburger, Mahony et al., 2010) translated into Portuguese. Data collection took place between February and July 2014, in compliance with ethical research guidelines. The sample comprised 59 children, 59 parents of children, 80 adolescents and 80 parents of adolescents. Results: The results indicated that children, adolescents, and their parents have high level of perceived health. The results are similar in all groups: children and parents and adolescents and parents. In the group of children, we observed the classification of "Good" in 66.10%, followed by the "Very Good" at 18.65% and "fair" in 15.25% of cases. The parents of the children responded in about half the cases that the health of their children was "good" (50.85%), "very good" in 30.51% "fair" in 11.86% and "Excellent "in 6.78%. In turn, the group of adolescents can be seen that 46.25% rate their health as "good", 32.50% as "very good", 16.25% as "Average" and 5% as "Excellent". Parents of teenagers classify the health of their children mostly as "good" in 42.50%, 31.25% as "very good", 20% as "fair" and 6.25% as "excellent". To point out that none of the respondents pointed out the option of a health status "Bad". About the quality of life, in general the results indicated that children, adolescents and their parents have high levels of quality of life, and that perceptions of parents and children are similar. Only in the children?s group (8 to 12 years old), was no influence of socio-demographic, school or clinical variables on quality of life observed. For adolescents (13 to 18 years old), school, special education, school retention, the age of diagnosis of congenital heart disease, cardiac catheterization and surgical intervention influenced their quality of life. Perception of quality of life of parents of children and of adolescents was influenced by socio-demographic and clinical variables. The results partly agree with the literature in this field. About the influence of some variables: The perception of quality of life expressed by children and adolescents with congenital heart disease and parents are related, with statistical significance. There were no statistically significant relationships between the quality of life of children and adolescents and their age, gender or socioeconomic status. Adolescents differ statistically significant between their quality of life and their education, the frequency of special education and the existence of grade retention. The severity of heart disease, the number of cardiac catheterizations or surgery and the presence of other health disorders are unrelated to the quality of life of children and adolescents. Adolescents revealed that the level of quality of life is influenced by the age of diagnosis of CHD by cardiac catheterization and surgery. For parents of children and adolescents gender and their education don?t influence their perception of quality of life. Only the socioeconomic status of parents of teens has statistically significant difference to quality of life. Parents of children and adolescents do not show statistically significant relationship between the perceived level of quality of life and severity of disease, age at diagnosis, the number of surgical interventions and the existence of other health disorders. There is a relationship of statistical significance between cardiac catheterization and the perceived quality of life by parents of adolescents; between the number of cardiac catheterizations and the perception of quality of life of parents of children; and between performing surgery and the perception of parents of children and adolescents. Conclusion: To analyze the quality of life of children and adolescents with CHD must be a key focus of attention in caring for this population, allowing the identification of individual differences, interests, preferences, and prevent potential problems. The knowledge acquired along with clinical experience contributes to improve the quality of life of children and families, facilitating their growth, psycho-emotional development and social integration. Nevertheless, the reading and interpretation of these results must be prudent and cautious, there are limitations to this research, including: the use of a range of specific quality of life for the Congenital heart disease in children, adolescents, and parents but whose validation process could not be completed in this study; the low prevalence of severe conditions in our sample; the absence of national studies to enable comparison with the results obtained. We intend to continue the process of validation of instrument and enlarge the research to Lisbon and Oporto, other major centers where the cardiac conditions can be treated.
Resumo:
Let X be a geometrically irreductble smooth projective cruve defined over R. of genus at least 2. that admits a nontrivial automorphism, sigma. Assume that X does not have any real points. Let tau be the antiholomorphic involution of the complexification lambda(C) of X. We show that if the action of sigma on the set S(X) of all real theta characteristics of X is trivial. then the order of sigma is even, say 2k and the automorphism tau o (sigma) over cap (lambda) of X-C has a fixed point, where (sigma) over cap is the automorphism of X x C-R defined by sigma We then show that there exists X with a real point and admitting a nontrivial automorphism sigma, such that the action of sigma on S(X) is trivial, while X/
Resumo:
The delay stochastic simulation algorithm (DSSA) by Barrio et al. [Plos Comput. Biol.2, 117–E (2006)] was developed to simulate delayed processes in cell biology in the presence of intrinsic noise, that is, when there are small-to-moderate numbers of certain key molecules present in a chemical reaction system. These delayed processes can faithfully represent complex interactions and mechanisms that imply a number of spatiotemporal processes often not explicitly modeled such as transcription and translation, basic in the modeling of cell signaling pathways. However, for systems with widely varying reaction rate constants or large numbers of molecules, the simulation time steps of both the stochastic simulation algorithm (SSA) and the DSSA can become very small causing considerable computational overheads. In order to overcome the limit of small step sizes, various τ-leap strategies have been suggested for improving computational performance of the SSA. In this paper, we present a binomial τ- DSSA method that extends the τ-leap idea to the delay setting and avoids drawing insufficient numbers of reactions, a common shortcoming of existing binomial τ-leap methods that becomes evident when dealing with complex chemical interactions. The resulting inaccuracies are most evident in the delayed case, even when considering reaction products as potential reactants within the same time step in which they are produced. Moreover, we extend the framework to account for multicellular systems with different degrees of intercellular communication. We apply these ideas to two important genetic regulatory models, namely, the hes1 gene, implicated as a molecular clock, and a Her1/Her 7 model for coupled oscillating cells.
Resumo:
The presence of theta-class glutathione S-transferase (GST) in marmoset monkey liver cytosol was investigated. An anti-peptide antibody targeted against the C-terminus of rGSTT1 reacted with a single band in marmoset liver cytosol that corresponded to a molecular weight of 28 kDa. The intensity of the immunoreactive band was not affected by treatment of marmoset monkeys with 2,3,7,8-tetrachlorodibenzo-p-dioxin, phenobarbitone, rifampicin or clofibric acid. Similarly, activity towards methyl chloride (MC) was unaffected by these treatments. However, GST activity towards 1,2-epoxy3-(p- nitrophenoxy)-propane (EPNP) was increased in marmosets treated with phenobarbitone (2.6-fold) and rifampicin (2.6-fold), activity towards dichloromethane (DCM) was increased by 50% after treatment of marmosets with clofibric acid, and activity towards 1-chloro-2,4-dinitrobenzene (CDNB) was raised slightly (30-42% increases) after treatment with phenobarbitone, rifampicin or clofibric acid. Compared with humans, marmoset liver cytosol GST activity towards DCM was 18-fold higher, activity towards MC was 7 times higher and activity towards CDNB was 4 times higher. Further, EPNP activity was clearly detectable in marmoset liver cytosol samples, but was undetectable in human samples. Immunoreactive marmoset GST was partially purified by affinity chromatography using hexylglutathione-Sepharose and Orange A resin. The interaction of immunoreactive marmoset GST was similar to that found previously for rat and human GSTT1, suggesting that this protein is also a theta class GST. However, unlike rat GSTT1, the marmoset enzyme was not the major catalyst of EPNP conjugation. Instead, immunoreactivity was closely associated with activity towards MC. In conclusion, these results provide evidence for the presence of theta-class GST in the marmoset monkey orthologous to rGSTT1 and hGSTT1.
Resumo:
The transformation of ethylene oxide (EO), propylene oxide (PO) and 1- butylene oxide (1-BuO) by human glutathione transferase theta (hGSTT1-1) was studied comparatively using 'conjugator' (GSTT1 + individuals) erythrocyte lysates. The relative sequence of velocity of enzymic transformation was PO > EO >> 1-BuO. The faster transformation of PO compared to EO was corroborated in studies with human and rat GSTT1-1 (hGSTT1-1 and rGSTT1-1, respectively) expressed by Salmonella typhimurium TA1535. This sequence of reactivities of homologous epoxides towards GSTT1-1 contrasts to the sequence observed in homologous alkyl halides (methyl bromide, MBr; ethyl bromide, EtBr; n-propyl bromide, PrBr) where the relative sequence MeBr >> EtBr > PrBr is observed. The higher reactivity towards GSTT1-1 of propylene oxide compared to ethylene oxide is consistent with a higher chemical reactivity. This is corroborated by experimental data of acid-catalysed hydrolysis of a number of aliphatic epoxides, including ethylene oxide and propylene oxide and consistent with semi-empirical molecular orbital modelings.
Resumo:
Glutathione transferases (GSTs) catalyzing the conjugation of glutathione with electrophilic substrates are important enzymes in the metabolism of xenobiotics. Several isozymes exhibit polymorphisms in humans. The two deletion polymorphisms of hGSTM1 and hGSTT1 result in total loss of enzyme activity in homozygous null genotype (GSTM1*0 and GSTT1*0 respectively) individuals (Seidegård et al. 1988; Pemble et al. 1994). Individuals that are heterozygous for hGSTT1 show distinctly lower enzyme activities than individuals carrying two functional alleles of hGSTT1 (Wiebel et al. 1996). A similar effect is conceivable for the hGSTM1 polymorphism but has not been verified so far.
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In this paper, we introduce the Stochastic Adams-Bashforth (SAB) and Stochastic Adams-Moulton (SAM) methods as an extension of the tau-leaping framework to past information. Using the theta-trapezoidal tau-leap method of weak order two as a starting procedure, we show that the k-step SAB method with k >= 3 is order three in the mean and correlation, while a predictor-corrector implementation of the SAM method is weak order three in the mean but only order one in the correlation. These convergence results have been derived analytically for linear problems and successfully tested numerically for both linear and non-linear systems. A series of additional examples have been implemented in order to demonstrate the efficacy of this approach.
Resumo:
The minimal supergravity model predicts the polarization of the tau coming from the stau to bino decay in the co-annihilation region to +1. This can be exploited to extract this soft tau signal at LHC and also to measure the tiny mass differences between the stau and the bi lightest superparticle. Moreover, this strategy will be applicable for a wider class of bino lightest superparticle models, where the lighter stau has a right component at least of similar size as the left.
Resumo:
Post mortem biochemical staging of Alzheimer’s disease is currently based on immunochemical analysis of brain slices with the AT8 antibody. The epitope of AT8 is described around the pSer202/pThr205 region of the hyperphosphorylated form of the neuronal protein tau. In this study, NMR spectroscopy was used to precisely map the AT8 epitope on phosphorylated tau, and derive its defining structural features by a combination of NMR analyses and molecular dynamics. A particular turn conformation is stabilized by a hydrogen bond of the phosphorylated Thr205 residue to the amide proton of Gly207, and is further stabilized by the two Arg residues opposing the pSer202/pThr205.
Resumo:
Aggregation of the microtubule associated protein tau (MAPT) within neurons of the brain is the leading cause of tauopathies such as Alzheimer's disease. MAPT is a phospho-protein that is selectively phosphorylated by a number of kinases in vivo to perform its biological function. However, it may become pathogenically hyperphosphorylated, causing aggregation into paired helical filaments and neurofibrillary tangles. The phosphorylation induced conformational change on a peptide of MAPT (htau225−250) was investigated by performing molecular dynamics simulations with different phosphorylation patterns of the peptide (pThr231 and/or pSer235) in different simulation conditions to determine the effect of ionic strength and phosphate charge. All phosphorylation patterns were found to disrupt a nascent terminal β-sheet pattern (226VAVVR230 and 244QTAPVP249), replacing it with a range of structures. The double pThr231/pSer235 phosphorylation pattern at experimental ionic strength resulted in the best agreement with NMR structural characterization, with the observation of a transient α-helix (239AKSRLQT245). PPII helical conformations were only found sporadically throughout the simulations. Proteins 2014; 82:1907–1923. © 2014 Wiley Periodicals, Inc.
Resumo:
ALUMINIUM exposure has been shown to result in aggregation of microtubule-associated protein tau in vitro. In the light of recent observations that the native random structure of tau protein is maintained in its monomeric and dimeric states as well as in the paired helical filaments characteristic of Alzheimer's disease, it is likely that factors playing a causative role in neurofibrillary pathology would not drastically alter the native conformation of tau protein. We have studied the interaction of tau protein with aluminium using circular dichroism (CD) and 27(Al) NMR spectroscopy. The CD studies revealed a five-fold increase in the observed ellipticity of the tau-aluminium assembly. The increase in elipticity was not associated with a change in the general conformation of the protein and was most likely due to an aggregation of the tau protein induced by aluminium. Al-27 NMR spectroscopy confirmed the binding of aluminium to tau protein. Hyperphosphorylation of tau in Alzheimer's disease is known to be associated with defective microtubule assembly in this condition. Abnormally phosphorylated tau exists in a polymerized form in the paired helical filaments (PHF) which constitute the neurofibrillary tangles found in Alzheimer's disease. While it is hypothesized that its altered biophysical characteristics render abnormally phosphorylated tau resistant to proteolysis, causing the formation of stable deposits,the sequence of events resulting in the polymerization of tau are little understood, as are the additional factors or modifications required for tills process. Based on the results of our spectroscopic studies, a model for the sequence of events occurring in neurofibrillary pathology is proposed.
Resumo:
Partitional clustering algorithms, which partition the dataset into a pre-defined number of clusters, can be broadly classified into two types: algorithms which explicitly take the number of clusters as input and algorithms that take the expected size of a cluster as input. In this paper, we propose a variant of the k-means algorithm and prove that it is more efficient than standard k-means algorithms. An important contribution of this paper is the establishment of a relation between the number of clusters and the size of the clusters in a dataset through the analysis of our algorithm. We also demonstrate that the integration of this algorithm as a pre-processing step in classification algorithms reduces their running-time complexity.
Resumo:
This thesis describes methods for the reliable identification of hadronically decaying tau leptons in the search for heavy Higgs bosons of the minimal supersymmetric standard model of particle physics (MSSM). The identification of the hadronic tau lepton decays, i.e. tau-jets, is applied to the gg->bbH, H->tautau and gg->tbH+, H+->taunu processes to be searched for in the CMS experiment at the CERN Large Hadron Collider. Of all the event selections applied in these final states, the tau-jet identification is the single most important event selection criterion to separate the tiny Higgs boson signal from a large number of background events. The tau-jet identification is studied with methods based on a signature of a low charged track multiplicity, the containment of the decay products within a narrow cone, an isolated electromagnetic energy deposition, a non-zero tau lepton flight path, the absence of electrons, muons, and neutral hadrons in the decay signature, and a relatively small tau lepton mass compared to the mass of most hadrons. Furthermore, in the H+->taunu channel, helicity correlations are exploited to separate the signal tau jets from those originating from the W->taunu decays. Since many of these identification methods rely on the reconstruction of charged particle tracks, the systematic uncertainties resulting from the mechanical tolerances of the tracking sensor positions are estimated with care. The tau-jet identification and other standard selection methods are applied to the search for the heavy neutral and charged Higgs bosons in the H->tautau and H+->taunu decay channels. For the H+->taunu channel, the tau-jet identification is redone and optimized with a recent and more detailed event simulation than previously in the CMS experiment. Both decay channels are found to be very promising for the discovery of the heavy MSSM Higgs bosons. The Higgs boson(s), whose existence has not yet been experimentally verified, are a part of the standard model and its most popular extensions. They are a manifestation of a mechanism which breaks the electroweak symmetry and generates masses for particles. Since the H->tautau and H+->taunu decay channels are important for the discovery of the Higgs bosons in a large region of the permitted parameter space, the analysis described in this thesis serves as a probe for finding out properties of the microcosm of particles and their interactions in the energy scales beyond the standard model of particle physics.