967 resultados para rigorous results in statistical mechanics


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Objective. To describe the strategies and results obtained by the early diagnosis and prevention of an oral cancer campaign targeting the population aged 60 years or older developed since 2001 in the state of Sao Paulo. Methods. The main strategies used to develop the campaign were described based on the review of documents issued by the Health Ministry, National Cancer Institute, Sao Paulo State Health Department, Oncocentro Foundation of Sao Paulo, Sao Paulo City Health Department, School of Public Health at the University of Sao Paulo (USP), and Santa Marcelina Health Care Center. The impact of the campaign on the incidence of new cases of oral cancer in the target population was evaluated. Results. In 2001, 90 886 elderly were examined vs. 629 613 in 2009. The following strategies were identified: training of professionals, development of printed materials to guide municipal governments in developing the campaign and using standardized codes and criteria, guidelines for data consolidation, establishment of patient referral flows, practical training with a specialist at the basic health care unit after the follow-up examination of individuals presenting changes in soft tissues, and increase in the number of oral diagnosis services. Between 2005 and 2009, there was a significant reduction in the rate of confirmed cases of oral cancer per 100 000 individuals examined, from 20.89 to 11.12 (P = 0.00003). Conclusions. The campaign was beneficial to the oral health of the elderly and could be extended to include other age groups and regions of the country. It may also provide a basis for the development of oral cancer prevention actions in other countries, as long as local characteristics are taken into account.

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BACKGROUND: Neoadjuvant chemoradiation (CRT) therapy may result in significant tumor regression in patients with rectal cancer. Patients who develop complete tumor regression have been managed by treatment strategies that are alternatives to standard total mesorectal excision. Therefore, assessment of tumor response with positron emission tomography/computed tomography (PET/CT) after neoadjuvant treatment may offer relevant information for the selection of patients to receive alternative treatment strategies. METHODS: Patients with clinical T2 (cT2) through cT4NxM0 rectal adenocarcinoma were included prospectively. Neoadjuvant therapy consisted of 54 grays of radiation and 5-fluorouracil-based chemotherapy. Baseline PET/CT studies were obtained before CRT followed by PET/CT studies at 6 weeks and 12 weeks after the completion of CRT. Clinical assessment was performed at 12 weeks after CRT completion. PET/CT results were compared with clinical and pathologic data. RESULTS: In total, 99 patients were included in the study. Twenty-three patients were complete responders (16 had a complete clinical response, and 7 had a complete pathologic response). The PET/CT response evaluation at 12 weeks indicated that 18 patients had a complete response, and 81 patients had an incomplete response. There were 5 false-negative and 10 false-positive PET/CT results. PET/CT for the detection of residual cancer had 93% sensitivity, 53% specificity, a 73% negative predictive value, an 87% positive predictive value, and 85% accuracy. Clinical assessment alone resulted in an accuracy of 91%. PET/CT information may have detected misdiagnoses made by clinical assessment alone, improving overall accuracy to 96%. CONCLUSIONS: Assessment of tumor response at 12 weeks after CRT completion with PET/CT imaging may provide a useful additional tool with good overall accuracy for the selection of patients who may avoid unnecessary radical resection after achieving a complete clinical response. Cancer 2012;35013511. (C) 2011 American Cancer Society.

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Objectives To analyse demographic and clinical variables in patients with disease onset before and after 40, 45 and 50 years in a large series of Brazilian SpA patients. Methods A common protocol of investigation was prospectively applied to 1424 SpA patients in 29 centres distributed through the main geographical regions in Brazil. The mean age at disease onset was 28.56 +/- 12.34 years, with 259 patients (18.2%) referring disease onset after 40 years, 15.1 (10.6%) after 45 years and 81 (5.8%) after 50 years. Clinical and demographic variables and disease indices (BASDAI, BASFI, BASRI, MASES, ASQoL) were investigated. Ankylosing spondylitis was the most frequent disease (66.3%), followed by psoriatic arthritis (18%), undifferentiated SpA (6.7%), reactive arthritis (5.5%), and enteropathic arthritis (3.5%). Results Comparing the groups according to age of disease onset, those patients with later onset presented statistical association with female gender, peripheral arthritis, dactylitis, nail involvement and psoriasis, as well as negative statistical association with inflammatory low hack pain, alternating buttock pain, radiographic sacroiliitis, hip involvement, positive familial history, HLA-B27 and uveitis. BASDAI, BASFI and quality of life, as well as physicians and patient's global assessment, were similar in all the groups. Radiographic indices showed worse results in the younger age groups. Conclusion There are two different clinical patterns in SpA defined by age at disease onset: one with predominance of axial symptoms in the group with disease onset <= 40 years and another favouring the peripheral manifestations in those with later disease onset.

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Background: There are no available statistical data about sudden cardiac death in Brazil. Therefore, this study has been conducted to evaluate the incidence of sudden cardiac death in our population and its implications. Methods: The research methodology was based on Thurstone's Law of Comparative Judgment, whose premise is that the more an A stimulus differs from a B stimulus, the greater will be the number of people who will perceive this difference. This technique allows an estimation of actual occurrences from subjective perceptions, when compared to official statistics. Data were collected through telephone interviews conducted with Primary and Secondary Care physicians of the Public Health Service in the Metropolitan Area of Sao Paulo (MASP). Results: In the period from October 19, 2009, to October 28, 2009, 196 interviews were conducted. The incidence of 21,270 cases of sudden cardiac death per year was estimated by linear regression analysis of the physicians responses and data from the Mortality Information System of the Brazilian Ministry of Health, with the following correlation and determination coefficients: r = 0.98 and r2= 0.95 (95% confidence interval 0.81.0, P < 0.05). The lack of waiting list for specialized care and socioadministrative problems were considered the main barriers to tertiary care access. Conclusions: The incidence of sudden cardiac death in the MASP is high, and it was estimated as being higher than all other causes of deaths; the extrapolation technique based on the physicians perceptions was validated; and the most important bureaucratic barriers to patient referral to tertiary care have been identified. (PACE 2012; 35:13261331)

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The development of new statistical and computational methods is increasingly making it possible to bridge the gap between hard sciences and humanities. In this study, we propose an approach based on a quantitative evaluation of attributes of objects in fields of humanities, from which concepts such as dialectics and opposition are formally defined mathematically. As case studies, we analyzed the temporal evolution of classical music and philosophy by obtaining data for 8 features characterizing the corresponding fields for 7 well-known composers and philosophers, which were treated with multivariate statistics and pattern recognition methods. A bootstrap method was applied to avoid statistical bias caused by the small sample data set, with which hundreds of artificial composers and philosophers were generated, influenced by the 7 names originally chosen. Upon defining indices for opposition, skewness and counter-dialectics, we confirmed the intuitive analysis of historians in that classical music evolved according to a master apprentice tradition, while in philosophy changes were driven by opposition. Though these case studies were meant only to show the possibility of treating phenomena in humanities quantitatively, including a quantitative measure of concepts such as dialectics and opposition, the results are encouraging for further application of the approach presented here to many other areas, since it is entirely generic.

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The self-consistency of a thermodynamical theory for hadronic systems based on the non-extensive statistics is investigated. We show that it is possible to obtain a self-consistent theory according to the asymptotic bootstrap principle if the mass spectrum and the energy density increase q-exponentially. A direct consequence is the existence of a limiting effective temperature for the hadronic system. We show that this result is in agreement with experiments. (C) 2012 Elsevier B.V. All rights reserved.

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Objectives/Hypothesis. Hepatocyte growth factor (HGF) is a multifunctional polypeptide that plays various roles in embryogenesis and tissue regeneration and exhibits marked antifibrotic activity. The present study sought to assess the effects of HGF injection and reinjection coinciding with its peak of activity on collagen density, vessel density, inflammatory reaction in the lamina propria, and mean epithelial thickness in the injured rabbit vocal fold. Study Design. Prospective, controlled, experimental animal study. Methods. Fourteen rabbits were subdivided into two groups and underwent injury of the vocal folds. Immediately after injury, animals in group 1 received HGF injections into the right vocal fold (RVF), whereas those in group 2 received bilateral HGF injections and a single reinjection into the RVF 10 days after the first, to coincide with the peak of HGF activity. The left vocal folds (LVFs) served as controls in both groups. Histological assessment of laryngeal specimens was performed at 30 and 40 days, respectively. Results. In both groups, collagen density was lower in the right (treated) vocal folds than in the left (control) folds (P = 0.018). Vessel density was higher in the RVFs in group 2 (P = 0.018). Differences were found in mean epithelial thickness and inflammatory reaction in the lamina propria but did not reach statistical significance. Conclusions. In the scarred rabbit vocal fold, HGF injection is associated with decreased collagen density in the lamina propria, whereas reinjection after 10 days produces decreased collagen density and higher vessel density.

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In this work, a new enrichment space to accommodate jumps in the pressure field at immersed interfaces in finite element formulations, is proposed. The new enrichment adds two degrees of freedom per element that can be eliminated by means of static condensation. The new space is tested and compared with the classical P1 space and to the space proposed by Ausas et al (Comp. Meth. Appl. Mech. Eng., Vol. 199, 10191031, 2010) in several problems involving jumps in the viscosity and/or the presence of singular forces at interfaces not conforming with the element edges. The combination of this enrichment space with another enrichment that accommodates discontinuities in the pressure gradient has also been explored, exhibiting excellent results in problems involving jumps in the density or the volume forces. Copyright (c) 2011 John Wiley & Sons, Ltd.

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Abstract Background Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of Mycobacterium tuberculosis (MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection. Methods To evaluate the performance of the PCR dot-blot in parallel with pretest probability (Clinical Suspicion) in patients suspected of having SNPTB, a prospective study of 213 individuals with clinical and radiological suspicion of SNPTB was carried out from May 2003 to May 2004, in a TB/HIV reference hospital. Respiratory specialists estimated the pretest probability of active disease into high, intermediate, low categories. Expectorated sputum was examined by direct microscopy (Ziehl-Neelsen staining), culture (Lowenstein Jensen) and PCR dot-blot. Gold standard was based on culture positivity combined with the clinical definition of PTB. Results In smear-negative and HIV subjects, active PTB was diagnosed in 28.4% (43/151) and 42.2% (19/45), respectively. In the high, intermediate and low pretest probability categories active PTB was diagnosed in 67.4% (31/46), 24% (6/25), 7.5% (6/80), respectively. PCR had sensitivity of 65% (CI 95%: 50%–78%) and specificity of 83% (CI 95%: 75%–89%). There was no difference in the sensitivity of PCR in relation to HIV status. PCR sensitivity and specificity among non-previously TB treated and those treated in the past were, respectively: 69%, 43%, 85% and 80%. The high pretest probability, when used as a diagnostic test, had sensitivity of 72% (CI 95%:57%–84%) and specificity of 86% (CI 95%:78%–92%). Using the PCR dot-blot in parallel with high pretest probability as a diagnostic test, sensitivity, specificity, positive and negative predictive values were: 90%, 71%, 75%, and 88%, respectively. Among non-previously TB treated and HIV subjects, this approach had sensitivity, specificity, positive and negative predictive values of 91%, 79%, 81%, 90%, and 90%, 65%, 72%, 88%, respectively. Conclusion PCR dot-blot associated with a high clinical suspicion may provide an important contribution to the diagnosis of SNPTB mainly in patients that have not been previously treated attended at a TB/HIV reference hospital.

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Abstract Background H. pylori seroprevalence in Brazilians varies and is dependent on socioeconomic status, sanitation conditions and ethnicity; furthermore, H. pylori is not always associated with the incidence of gastric cancer, suggesting the role of more virulent strains. The purpose of this study was to analyze the association of more virulent H. pylori strains with gastric cancer. Methods DNA was extracted from gastric biopsies of thirty-four cases of gastric cancer (11 intestinal-type, 23 diffuse-type), and thirty-four of patients with endoscopic gastritis. The presence of cagPAI genes (cagA, cagA promoter, cagE, cagM, tnpB, tnpA, cagT and the left end of the cagII (LEC)) and babA were analyzed by PCR. Results Comparison of H. pylori isolates from gastric cancer and gastritis patients showed significant associations of tnpA and LEC with gastric cancer (73.5% [OR, 6.66; 95% CI, 2.30-19.25] and 58.8% [OR, 10.71; 95% CI, 3.07-37.28] of cases, respectively). Other cagPAI genes were detected in both groups at similar frequencies. Conclusions tnpA and LEC of H. pylori cagPAI were associated with gastric cancer; nonetheless, these results were restricted within this group of patients and further studies are needed to confirm these results in a larger sample and determine their role in gastric carcinogenesis.

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Objective: To evaluate the influence of myofascial pain on the Pressure Pain Threshold (PPT) of masticatory muscles in women with migraine. Methods: The sample comprised 101 women, ages ranging from 18 to 60 years, with an episodic migraine diagnosis previously confirmed by a neurologist. All patients were evaluated using Research Diagnostic Criteria for Temporomandibular Disorders to determine the presence of myofascial pain and were divided into 2 groups: group I (n=56), comprising women with a migraine, and group II (n=45), comprising women with a migraine and myofascial pain. Two more groups (49 asymptomatic women and 50 women with myofascial pain), matched for sex and race, obtained from a previous study, were added to this study. The PPT values of masseter and temporalis (anterior, middle, and posterior regions) muscles were recorded bilaterally using a pressure algometer. One-way analysis of variance and the Tukey test for pairwise comparisons were used in statistical analysis with a 5% significance level. Results: We found that all groups had significantly lower PPT values compared with asymptomatic women, with lower values seen in group II (women with migraine and myofascial pain). Women with a migraine and myofascial pain showed significantly lower PPT values compared with women with a migraine only, and also when compared with women with myofascial pain only. Discussion: Migraine, especially when accompanied by myofascial pain, reduces the PPT of masticatory muscles, suggesting the importance of masticatory muscle palpation during examination of patients with migraine.

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Abstract Background Lung cancer often exhibits molecular changes, such as the overexpression of the ErbB1 gene. ErbB1 encodes epidermal growth factor receptor (EGFR), a tyrosine kinase receptor, involved mainly in cell proliferation and survival. EGFR overexpression has been associated with more aggressive disease, poor prognosis, low survival rate and low response to therapy. ErbB1 amplification and mutation are associated with tumor development and are implicated in ineffective treatment. The aim of the present study was to investigate whether the ErbB1 copy number affects EGFR expression, cell proliferation or cell migration by comparing two different cell lines. Methods The copies of ErbB1 gene was evaluated by FISH. Immunofluorescence and Western blotting were performed to determine location and expression of proteins mentioned in the present study. Proliferation was studied by flow cytometry and cell migration by wound healing assay and time lapse. Results We investigated the activation and function of EGFR in the A549 and HK2 lung cancer cell lines, which contain 3 and 6 copies of ErbB1, respectively. The expression of EGFR was lower in the HK2 cell line. EGFR was activated after stimulation with EGF in both cell lines, but this activation did not promote differences in cellular proliferation when compared to control cells. Inhibiting EGFR with AG1478 did not modify cellular proliferation, confirming previous data. However, we observed morphological alterations, changes in microfilament organization and increased cell migration upon EGF stimulation. However, these effects did not seem to be consequence of an epithelial-mesenchymal transition. Conclusion EGFR expression did not appear to be associated to the ErbB1 gene copy number, and neither of these aspects appeared to affect cell proliferation. However, EGFR activation by EGF resulted in cell migration stimulation in both cell lines.

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Abstract Background HPV persistence is a key determinant of cervical carcinogenesis. The influence of postpartum on HPV clearance has been debated. This study aimed to assess HPV clearance in later pregnancy and postpartum among HIV-positive and negative women. Methods We conducted a follow-up study with 151 HPV-positive women coinfected with HIV, in 2007–2010. After baseline assessment, all women were retested for HPV infection using PCR in later pregnancy and after delivery. Multivariable logistic regressions assessed the putative association of covariates with HPV status in between each one of the successive visits. Results Seventy-one women (47%) have eliminated HPV between the baseline visit and their second or third visits. HIV-positive women took a significantly longer time (7.0 ± 3.8 months) to clear HPV, compared to those not infected by HIV (5.9 ± 3.0 months). HPV clearance was significantly more likely to take place after delivery than during pregnancy (84.5% x 15.5%). Conclusions Both HIV-positive and negative women presented a significant reduction in HPV infection during the postpartum period. HIV-positive status was found to be associated with a longer period of time to clear HPV infection in pregnant women.

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Abstract: Background Pancreatic cancer is a rare tumor with an extremely low survival rate. Its known risk factors include the chronic use of tobacco and excessive alcohol consumption and the presence of chronic inflammatory diseases, such as pancreatitis and type 2 diabetes. Angiogenesis and lymphangiogenesis, which have been the focus of recent research, are considered prognostic factors for cancer development. Knowing the angiogenic and lymphangiogenic profiles of a tumor may provide new insights for designing treatments according to the different properties of the tumor. The aim of this study was to evaluate the density of blood and lymphatic vessels, and the expression of VEGF-A, in pancreatic adenocarcinomas, as well as the relationship between blood and lymphatic vascular density and the prognostically important clinical-pathological features of pancreatic tumors. Methods Paraffin blocks containing tumor samples from 100 patients who were diagnosed with pancreatic cancer between 1990 and 2010 were used to construct a tissue microarray. VEGF expression was assessed in these samples by immunohistochemistry. To assess the lymphatic and vascular properties of the tumors, 63 cases that contained sufficient material were sectioned routinely. The sections were then stained with the D2-40 antibody to identify the lymphatic vessels and with a CD34 antibody to identify the blood vessels. The vessels were counted individually with the Leica Application Suite v4 program. All statistical analyses were performed using SPSS 18.0 (Chicago, IL, USA) software, and p values ≤ 0.05 were considered significant. Results In the Cox regression analysis, advanced age (p=0.03) and a history of type 2 diabetes (p=0.014) or chronic pancreatitis (p=0.02) were shown to be prognostic factors for pancreatic cancer. Blood vessel density (BVD) had no relationship with clinical-pathological features or death. Lymphatic vessel density (LVD) was inversely correlated with death (p=0.002), and by Kaplan-Meyer survival analysis, we found a significant association between low LVD (p=0.021), VEGF expression (p=0.023) and low patient survival. Conclusions Pancreatic carcinogenesis is related to a history of chronic inflammatory processes, such as type 2 diabetes and chronic pancreatitis. In pancreatic cancer development, lymphangiogenesis can be considered an early event that enables the dissemination of metastases. VEGF expression and low LVD can be considered as poor prognostic factors as tumors with this profile are fast growing and highly aggressive. Virtual slides. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5113892881028514

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Reproducing Fourier's law of heat conduction from a microscopic stochastic model is a long standing challenge in statistical physics. As was shown by Rieder, Lebowitz and Lieb many years ago, a chain of harmonically coupled oscillators connected to two heat baths at different temperatures does not reproduce the diffusive behaviour of Fourier's law, but instead a ballistic one with an infinite thermal conductivity. Since then, there has been a substantial effort from the scientific community in identifying the key mechanism necessary to reproduce such diffusivity, which usually revolved around anharmonicity and the effect of impurities. Recently, it was shown by Dhar, Venkateshan and Lebowitz that Fourier's law can be recovered by introducing an energy conserving noise, whose role is to simulate the elastic collisions between the atoms and other microscopic degrees of freedom, which one would expect to be present in a real solid. For a one-dimensional chain this is accomplished numerically by randomly flipping - under the framework of a Poisson process with a variable “rate of collisions" - the sign of the velocity of an oscillator. In this poster we present Langevin simulations of a one-dimensional chain of oscillators coupled to two heat baths at different temperatures. We consider both harmonic and anharmonic (quartic) interactions, which are studied with and without the energy conserving noise. With these results we are able to map in detail how the heat conductivity k is influenced by both anharmonicity and the energy conserving noise. We also present a detailed analysis of the behaviour of k as a function of the size of the system and the rate of collisions, which includes a finite-size scaling method that enables us to extract the relevant critical exponents. Finally, we show that for harmonic chains, k is independent of temperature, both with and without the noise. Conversely, for anharmonic chains we find that k increases roughly linearly with the temperature of a given reservoir, while keeping the temperature difference fixed.