916 resultados para hadron elastic and transition form factors


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A computer simulation method has been used to study the three-dimensional structural formation and transition of eleetromagnetorheological (EMR) suspensions under compatible electric and magnetic fields. When the fields are applied simultaneously and perpendicularly to each other, the particles rapidly arrange into single layer structures parallel to both fields. In each layer, there is a two-dimensional hexagonal lattice. The single layers then combine together to form thicker sheetlike structures. With the help of the thermal fluctuations, the thicker structures relax into three-dimensional close-packed structures, which may be face-centered cubic (fcc), hexagonal close-packed (hup) lattices, or, more probably, the mixture of them, depending on the initial configurations and the thermal fluctuations. On the other hand, if the electric field is applied first to induce the body-centered tetragonal (bct) columns in the system, and then the magnetic field is applied in the perpendicular direction, the bet to fee structure transition is observed in a very short time. Following that, the structure keeps on evolving due to the demagnetization effect and finally forms close-packed structures with fee and hcp lattice character. The simulation results are in agreement with the theoretical and experimental results.

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A semi-classical approach is used to obtain Lorentz covariant expressions for the form factors between the kink states of a quantum field theory with degenerate vacua. Implemented on a cylinder geometry it provides an estimate of the spectral representation of correlation functions in a finite volume. Illustrative examples of the applicability of the method are provided by the sine-Gordon and the broken phi(4) theories in 1 + 1 dimensions. (C) 2003 Elsevier B.V. All rights reserved.

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We study the effect of bound nucleon form factors on charged-current neutrino-nucleus scattering. The bound nucleon form factors of the vector and axial-vector currents are calculated in the quark-meson coupling model. We compute the inclusive C-12(nu(mu),mu(-))X cross sections using a relativistic Fermi gas model with the calculated bound nucleon form factors. The effect of the bound nucleon form factors for this reaction is a reduction of similar to8% for the total cross section, relative to that calculated with the free nucleon form factors.

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We investigate the effect of different forms of relativistic spin coupling of constituent quarks in the nucleon electromagnetic form factors. The four-dimensional integrations in the two-loop Feynman diagram are reduced to the null-plane, such that the light-front wave function is introduced in the computation of the form factors. The neutron charge form factor is very sensitive to different choices of spin coupling schemes, once its magnetic moment is fitted to the experimental value. The scalar coupling between two quarks is preferred by the neutron data, when a reasonable fit of the proton magnetic momentum is found. (C) 2000 Elsevier Science B.V.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Madagascar’s terrestrial and aquatic ecosystems have long supported a unique set of ecological communities, many of whom are endemic to the tropical island. Those same ecosystems have been a source of valuable natural resources to some of the poorest people in the world. Nevertheless, with pride, ingenuity and resourcefulness, the Malagasy people of the southwest coast, being of Vezo identity, subsist with low development fishing techniques aimed at an increasingly threatened host of aquatic seascapes. Mangroves, sea grass bed, and coral reefs of the region are under increased pressure from the general populace for both food provisions and support of economic opportunity. Besides purveyors and extractors, the coastal waters are also subject to a number of natural stressors, including cyclones and invasive, predator species of both flora and fauna. In addition, the aquatic ecosystems of the region are undergoing increased nutrient and sediment runoff due, in part, to Madagascar’s heavy reliance on land for agricultural purposes (Scales, 2011). Moreover, its coastal waters, like so many throughout the world, have been proven to be warming at an alarming rate over the past few decades. In recognizing the intimate interconnectedness of the both the social and ecological systems, conservation organizations have invoked a host of complimentary conservation and social development efforts with the dual aim of preserving or restoring the health of both the coastal ecosystems and the people of the region. This paper provides a way of thinking more holistically about the social-ecological system within a resiliency frame of understanding. Secondly, it applies a platform known as state-and-transition modeling to give form to the process. State-and-transition modeling is an iterative investigation into the physical makeup of a system of study as well as the boundaries and influences on that state, and has been used in restorative ecology for more than a decade. Lastly, that model is sited within an adaptive management scheme that provides a structured, cyclical, objective-oriented process for testing stakeholders cognitive understanding of the ecosystem through a pragmatic implementation and monitoring a host of small-scale interventions developed as part of the adaptive management process. Throughout, evidence of the application of the theories and frameworks are offered, with every effort made to retool conservation-minded development practitioners with a comprehensive strategy for addressing the increasingly fragile social-ecological systems of southwest Madagascar. It is offered, in conclusion, that the seascapes of the region would be an excellent case study worthy of future application of state-and-transition modeling and adaptive management as frameworks for conservation-minded development practitioners whose multiple projects, each with its own objective, have been implemented with a single goal in mind: preserve and protect the state of the supporting environment while providing for the basic needs of the local Malagasy people.

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We analyze the pion transition form factor using dispersion theory. We calculate the singly-virtual form factor in the time-like region based on data for the e+e−→3π cross section, generalizing previous studies on ω,ϕ→3π decays and γπ→ππ scattering, and verify our result by comparing to e+e−→π0γ data. We perform the analytic continuation to the space-like region, predicting the poorly-constrained space-like transition form factor below 1GeV, and extract the slope of the form factor at vanishing momentum transfer aπ=(30.7±0.6)×10−3. We derive the dispersive formalism necessary for the extension of these results to the doubly-virtual case, as required for the pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon.

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To analyze associations between mammographic arterial mammary calcifications in menopausal women and risk factors for cardiovascular disease. This was a cross-sectional retrospective study, in which we analyzed the mammograms and medical records of 197 patients treated between 2004 and 2005. Study variables were: breast arterial calcifications, stroke, acute coronary syndrome, age, obesity, diabetes mellitus, smoking, and hypertension. For statistical analysis, we used the Mann-Whitney, χ2 and Cochran-Armitage tests, and also evaluated the prevalence ratios between these variables and mammary artery calcifications. Data were analyzed with the SAS version 9.1 software. In the group of 197 women, there was a prevalence of 36.6% of arterial calcifications on mammograms. Among the risk factors analyzed, the most frequent were hypertension (56.4%), obesity (31.9%), smoking (15.2%), and diabetes (14.7%). Acute coronary syndrome and stroke presented 5.6 and 2.0% of prevalence, respectively. Among the mammograms of women with diabetes, the odds ratio of mammary artery calcifications was 2.1 (95%CI 1.0-4.1), with p-value of 0.02. On the other hand, the mammograms of smokers showed the low occurrence of breast arterial calcification, with an odds ratio of 0.3 (95%CI 0.1-0.8). Hypertension, obesity, diabetes mellitus, stroke and acute coronary syndrome were not significantly associated with breast arterial calcification. The occurrence of breast arterial calcification was associated with diabetes mellitus and was negatively associated with smoking. The presence of calcification was independent of the other risk factors for cardiovascular disease analyzed.

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Frailty is a syndrome that leads to practical harm in the lives of elders, since it is related to increased risk of dependency, falls, hospitalization, institutionalization, and death. The objective of this systematic review was to identify the socio-demographic, psycho-behavioral, health-related, nutritional, and lifestyle factors associated with frailty in the elderly. A total of 4,183 studies published from 2001 to 2013 were detected in the databases, and 182 complete articles were selected. After a comprehensive reading and application of selection criteria, 35 eligible articles remained for analysis. The main factors associated with frailty were: age, female gender, black race/color, schooling, income, cardiovascular diseases, number of comorbidities/diseases, functional incapacity, poor self-rated health, depressive symptoms, cognitive function, body mass index, smoking, and alcohol use. Knowledge of the complexity of determinants of frailty can assist the formulation of measures for prevention and early intervention, thereby contributing to better quality of life for the elderly.

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Purpose. To understand the role of polymorphisms in the LEP (rs7799039 and rs2167270) and LEPR (rs1137101 and rs1137100) genes in DTC susceptibility and their effect on leptin levels. Methods. We studied 153 patients with DTC and 234 controls through TaqMan SNP Genotyping and ELISA, comparing these data to the clinicopathological data of patients with DTC. Results. Patients with AA genotype of rs7799039 had higher levels of serum leptin (9.22 ± 0.98 ng/mL) than those with AG genotype (10.07 ± 0.60 ng/mL; P = 0.005). Individuals with AG genotype of rs2167270 also produced higher serum leptin levels (10.05 ± 0.59 ng/mL) than the subjects with GG genotype (9.52 ± 0.79 ng/mL; P < 0.05). A multivariate logistic regression adjusted for gender, age, and BMI showed that the AG genotype of rs7799039 was an independent risk for DTC (OR, 11.689; P = 0.0183; 95% CI, 1.516-90.119). Similarly, AG and GG genotypes of rs1137101 increased the susceptibility to DTC (OR, 3.747; P = 0.027; 95% CI, 1.161-12.092 and OR, 5.437; P = 0.013; 95% CI, 1.426-20.729). Conclusions. We demonstrated that rs7799039 and rs2167270 polymorphisms modify the serum leptin concentrations in patients with DTC. Furthermore, polymorphisms rs7799039 and rs1137101 increase the risk of DTC development, although they do not correlate with tumor aggressiveness.

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FAPESP n. 03/04061-2

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High-precision data of backward-angle elastic and quasielastic scattering for the weakly bound (6)Li projectile on (144)Sm target at deep-sub-barrier, near-, and above-barrier energies were measured. From the deep-sub-barrier data, the surface diffuseness of the nuclear interacting potential was studied. Barrier distributions were extracted from the first derivatives of the elastic and quasielastic excitation functions. It is shown that sequential breakup through the first resonant state of the (6)Li is an important channel to be included in coupled-channels calculations, even at deep-sub-barrier energies.

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Background and Purpose-Few community-based studies have examined the long-term survival and prognostic factors for death within 5 years after an acute first-ever stroke. This study aimed to determine the absolute and relative survival and the independent baseline prognostic Factors for death over the next 5 years among all individuals and among 30-day survivors after a first-ever stroke in a population of Perth, Western Australia. Methods-Between February 1989 and August 1990, all individuals with a suspected acute stroke or transient ischemic attack of the brain who were resident in a geographically defined region of Perth, Western Australia, with a population of 138 708 people, were registered prospectively and assessed according to standardized diagnostic criteria. Patients were followed up prospectively at 4 months, 12 months, and 5 years after the index event. Results-Three hundred seventy patients with first-ever stroke were registered, and 362 (98%) were followed up at 5 years, by which time 210 (58%) had died. In the first year after stroke the risk of death was 36.5% (95% CI, 31.5% to 41.4%), which was 10-fold (95% CI, 8.3% to 11.7%) higher than that expected among the general population of the same age and sex. The most common cause of death was the index stroke (64%). Between 1 and 5 years after stroke, the annual risk of death was approximately 10% per year, which was approximately 2-fold greater than expected, and the most common cause of death was cardiovascular disease (41%). The independent baseline factors among 30-day survivors that predicted death over 5 years were intermittent clandication (hazard ratio [WR], 1.9; 95% CI, 1.2 to 2.9), urinary incontinence (HR, 2.0; 95% CI, 1.3 to 3.0), previous transient ischemic attack (HR, 2.4; 95% CT, 1.3 to 4.1), and prestroke Barthel Index <20/20 (HR, 2.0, 95% CI, 1.3 to 3.2). Conclusions-One-year survivors of first-ever stroke continue to die over the next 4 years at a rate of approximately 10% per year, which is twice the rate expected among the general population of the same age and sex. The most common cause of death is cardiovascular disease. Long-term survival after stroke may be improved by early, active, and sustained implementation of effective strategies for preventing subsequent cardiovascular events.