948 resultados para Bayes credible intervals
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Dissertação de Mestrado apresentada ao Instituto Superior de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Contabilidade e Finanças, sob orientação do Dr. Rodrigo Mário de Oliveira Carvalho
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This work aims to evaluate the impact of drug treatment on infection by Ascaris lumbricoides (Al), Trichuris trichiura (Tt) and hookworms (Hook) in a rural community from the sugar-cane zone of Pernambuco, Brazil. Four parasitological surveys were carried out from March 2001 to March 2002. Individual diagnosis was based on eight slides (four by the Kato-Katz method and four by the Hoffman method) per survey. Infected subjects were assigned to two groups for treatment with either albendazole (n = 62) or mebendazole (n = 57). Prevalence of infection fell significantly (p < 0.05) one month after treatment: Al (from 47.7% to 6.6%); Tt (from 45.7% to 31.8%) and Hook (from 47.7% to 24.5%). One year after treatment, infections by Tt and Hook remained significantly below pre-control levels. A substantial decrease in single-infection cases and multiple infections was found. Egg-negative rate was significant for Al (94.0%), Hook (68.3%) but not for Tt (45.5%), and did not differ significantly between subjects treated with mebendazole or albendazole. Egg counts fell significantly in the individuals remaining positive for Tt. It is recommended that antihelminthic treatment should be selective and given at yearly intervals preferably with albendazole, due to its cost-effectiveness.
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We evaluated the immunogenicity of three recombinant hepatitis B vaccines, one Brazilian (Butang, Instituto Butantan) and two Korean vaccines (Euvax-B, LG Chemical Ltd. and Hepavax-Gene, Greencross Vaccine Corp.), administered intramuscularly to students aged 17 to 19 years in three 10-µg doses (corresponding to half the amount of antigen routinely used for adult vaccination) at intervals of one month between the first and second dose, and of four months between the second and third dose. A total of 316 students non-reactive for any serological marker of hepatitis B virus infection were vaccinated: 77 (24.4%) with the Butang vaccine, 71 (22.5%) with Euvax-B, 85 (26.9%) with Hepavax-Gene and, for comparison, 83 (26.2%) with Engerix-B (GlaxoSmithKline), whose efficacy in young adults at the dose used here has been confirmed in previous studies. Similar seroconversion rates (anti-HBs > 10 mIU/mL about one month after application of the third dose) were obtained for the Butang, Euvax-B, Hepavax-Gene and Engerix-B vaccines (96.2%, 98.6%, 96.5% and 97.6%, respectively). The frequency of good responders (anti-HBs > 100 mIU/mL) was also similar among students receiving the four vaccines (85.8%, 91.6%, 89.4% and 89.2%, respectively). The geometric mean titers (GMT) of anti-HBs about one month after the third dose obtained with these vaccines were 727.78 ± 6.46 mIU/mL, 2009.09 ± 7.16 mIU/mL, 1729.82 ± 8.85 mIU/mL and 2070.14 ± 11.69 mIU/mL, respectively. The GMT of anti-HBs induced by the Euvax-B and Engerix-B vaccines were higher than those obtained with the Butang vaccine (p < 0.05); this difference was not significant when comparing the other vaccines two-by-two. No spontaneous adverse effects attributable to the application of any dose of the four vaccines were reported.
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Recently, operational matrices were adapted for solving several kinds of fractional differential equations (FDEs). The use of numerical techniques in conjunction with operational matrices of some orthogonal polynomials, for the solution of FDEs on finite and infinite intervals, produced highly accurate solutions for such equations. This article discusses spectral techniques based on operational matrices of fractional derivatives and integrals for solving several kinds of linear and nonlinear FDEs. More precisely, we present the operational matrices of fractional derivatives and integrals, for several polynomials on bounded domains, such as the Legendre, Chebyshev, Jacobi and Bernstein polynomials, and we use them with different spectral techniques for solving the aforementioned equations on bounded domains. The operational matrices of fractional derivatives and integrals are also presented for orthogonal Laguerre and modified generalized Laguerre polynomials, and their use with numerical techniques for solving FDEs on a semi-infinite interval is discussed. Several examples are presented to illustrate the numerical and theoretical properties of various spectral techniques for solving FDEs on finite and semi-infinite intervals.
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Erythema induratum of Bazin is a disease that usually affects women, in whom erythematous subcutaneous nodules and plaques appear on the posterior part of the lower extremities, some of which ulcerate. In many countries, tuberculosis is still the main etiologic factor. We report a case of a 40-year-old woman who presented a course of protracted and recurrent episodes over five years of cutaneous lesions on her legs. These tend to involute, but new crops appear at irregular intervals. It was painful, erythematous-violaceous nodules, some of which drained a reddish secretion. The histopathologic features of the lesions demonstrated inflammatory infiltration, with predominance of neutrophils in dermis and hypodermis, necrotizing vasculitis in the arterioles and septal fibrosis. There was no granuloma. The Ziehl-Neelsen stain did not revealed acid-fast bacilli, and the culture of biopsy specimen was negative. The tuberculin skin test was strongly positive (17 mm). The chest X-ray was normal. Few months later she presented adynamia and urinary complaints, such as polacyuria and dysuria. It has been done an urynalysis, which demonstrated acid pH urine, sterile pyuria and microscopic hematuria. It was then raised the diagnostic hypothesis of renal tuberculosis. The urine culture for M. tuberculosis was positive in two out of ten samples. The treatment was instituted with rifampin, isoniazid and pyrazinamide, with complete regression. This case illustrates a clear association between erythema induratum and renal tuberculosis, demonstrated by the remission of the cutaneous lesions after the treatment of the renal tuberculosis.
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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica
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The autonomic nervous system (ANS) is known to be an important modulator in the pathogenesis of paroxysmal atrial fibrillation (PAF). Changes in ANS control of heart rate variability (HRV) occur during orthostatism to maintain cardiovascular homeostasis. Wavelet transform has emerged as a useful tool that provides time-frequency decomposition of the signal under investigation, enabling intermittent components of transient phenomena to be analyzed. AIM: To study HRV during head-up tilt (HUT) with wavelet transform analysis in PAF patients and healthy individuals (normals). METHODS: Twenty-one patients with PAF (8 men; age 58 +/- 14 yrs) were examined and compared with 21 normals (7 men, age 48 +/- 12 yrs). After a supine resting period, all subjects underwent passive HUT (60 degrees) while in sinus rhythm. Continuous monitoring of ECG and blood pressure was carried out (Task Force Monitor, CNSystems). Acute changes in RR-intervals were assessed by wavelet analysis and low-frequency power (LF: 0.04-0.15 Hz), high-frequency power (HF: 0.15-0.60 Hz) and LF/HF (sympathovagal) were calculated for 1) the last 2 min of the supine period; 2) the 15 sec of tilting movement (TM); and 3) the 1st (TT1) and 2nd (TT2) min of HUT. Data are expressed as means +/- SEM. RESULTS: Baseline and HUT RR-intervals were similar for the two groups. Supine basal blood pressure was also similar for the two groups, with a sustained increase in PAF patients, and a decrease followed by an increase and then recovery in normals. Basal LF, HF and LF/ HF values in PAF patients were 632 +/- 162 ms2, 534 +/- 231 ms2 and 1.95 +/- 0.39 respectively, and 1058 +/- 223 ms2, 789 +/- 244 ms2 and 2.4 +/- 0.36 respectively in normals (p = NS). During TM, LF, HF and LF/HF values for PAF patients were 747 +/- 277 ms2, 387 +/- 94 ms2 and 2.9 +/- 0.6 respectively, and 1316 +/- 315 ms2, 698 +/- 148 ms2 and 2.8 +/- 0.6 respectively in normals (p < 0.05 for LF and HF). During TF1, LF, HF and LF/ HF values for PAF patients were 1243 +/- 432 ms2, 302 +/- 88 ms2 and 7.7 +/- 2.4 respectively, and 1992 +/- 398 ms2, 333 +/- 76 ms2 and 7.8 +/- 0.98 respectively for normals (p < 0.05 for LF). During TF2, LF, HF and LF/HF values for PAF patients were 871 +/- 256 ms2, 242 +/- 51 ms2 and 4.7 +/- 0.9 respectively, and 1263 +/- 335 ms2, 317 +/- 108 ms2 and 8.6 +/- 0.68 respectively for normals (p < 0.05 for LF/HF). The dynamic profile of HRV showed that LF and HF values in PAF patients did not change significantly during TM or TT2, and LF/HF did not change during TM but increased in TT1 and TT2. CONCLUSION: Patients with PAF present alterations in HRV during orthostatism, with decreased LF and HF power during TM, without significant variations during the first minutes of HUT. These findings suggest that wavelet transform analysis may provide new insights when assessing autonomic heart regulation and highlight the presence of ANS disturbances in PAF.
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Chagas disease can be transmitted to man by many different means, including contact with infected triatomine feces, blood transfusion, laboratory accidents, organ transplants, and congenital or oral routes. The latter mode has received considerable attention recently. In this assay, we evaluate the survival of Trypanosoma cruzi contaminating sugar cane used to prepare juice, as well as the viability and capacity for infection by the parasite after recovery. Thirty triatomines were contaminated with T. cruzi Y strain and 45 days later pieces of sugar cane were contaminated with the intestinal contents of the insects. The pieces were ground at different intervals after contamination (time = 0, 1, 4, 6, 12 and 24 hours) and the juice extracted and analyzed. Different methods were used to show T. cruzi in the juice: direct analysis, hematocrit tube centrifugation and QBC, and experimental inoculation in 47 female BALB/c mice (five control mice and seven mice for each interval examined (five inoculated orally and two intraperitoneally). Positive results were found using the direct analysis and QBC methods for juice prepared up to 12 hours after initial contamination. However, by the centrifugation technique, positivity was found only up to four hours after contamination of the sugar cane. Inoculated animals showed parasitemia during a 14 day observation period, demonstrating the high survival rate of T. cruzi in sugar cane.
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The kinetics of growth of Leishmania performed in vitro after internalization of the promastigote form in the cell and the occurrence of the transformation of the parasite into the amastigote form have been described by several authors. They used explants of macrophages in hamster spleen cell culture or in a human macrophage lineage cell, the U937. Using microscopy, the description of morphologic inter-relationship and the analysis of the production of specific molecules, it has been possible to define some of the peculiarities of the biology of the parasite. The present study shows the growth cycle of Leishmania chagasi during the observation of kinetic analysis undertaken with a McCoy cell lineage that lasted for a period of 144 hours. During the process, the morphologic transformation was revealed by indirect immunofluorescence (IF) and the molecules liberated in the extra cellular medium were observed by SDS-PAGE at 24-hour intervals during the whole 144-hour period. It was observed that in the first 72 hours the promastigote form of L. chagasi adhered to the cell membranes and assumed a rounded (amastigote-like) form. At 96 hours the infected cells showed morphologic alterations; at 120 hours the cells had liberated soluble fluorescent antigens into the extra cellular medium. At 144 hours, new elongated forms of the parasites, similar to promastigotes, were observed. In the SDS-PAGE, specific molecular weight proteins were observed at each point of the kinetic analysis showing that the McCoy cell imitates the macrophage and may be considered a useful model for the study of the infection of the Leishmania/cell binomial.
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As a result of the advances in the control of pulmonary insufficiency in tetanus, the cardiovascular system has increasingly been shown to be a determining factor in morbidity and mortality but detailed knowledge of the cardiovascular complications in tetanus is scanty. The 24h-Holter was carried out in order to detect arrhythmias and sympathetic overactivity in 38 tetanus patients admitted to an ICU. The SDNN Index (standard deviation from the normal R-to-R intervals), was useful in detecting adrenergic tonus, and ranged from 64.1 ± 27 in the more severe forms of tetanus to 125 ± 69 in the milder ones. Sympathetic overactivity occurred in 86.2% of the more severe forms of the disease, but was also detected in 33% of the milder forms. Half the patients had their sympathetic overactivity detected only by the Holter. The most frequent arrhythmias were isolated supraventricular (55.2%) and ventricular (39.4%) extrasystoles. There was no association of the arrhythmias with the clinical form of tetanus or with the presence of sympathetic overactivity. The present study demonstrated that major cardiovascular dysfunction, particularly sympathetic overactivity, occurs in all forms of tetanus, even in the milder ones. This has not been effectively detected with traditional monitoring in ICU and may not be properly treated.
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Although Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" infections have been reported in wild cats from United States, their presence among native and captive wild cats in Brazil is still unknown. A 12 year old healthy male lion (Panthera leo) from the Zoological Garden of Curitiba, Brazil was anesthetized for transportation and dental evaluation. A blood sample was obtained for a complete blood cell count (CBC) and PCR analysis. DNA was extracted and fragments of Mycoplasma haemofelis and "Candidatus Mycoplasma haemominutum" 16S ribosomal RNA gene were amplified in PCR assays. CBC results were within reference intervals. A weak band of 192 pb for "Candidatus Mycoplasma haemominutum" was observed, and no band was amplified from Mycoplasma haemofelis reaction. A weak PCR band associated with normal CBC results and without visible parasitemia or clinical signs may suggest a chronic subclinical infection with "Candidatus Mycoplasma haemominutum". The lack of clinical signs may also represent the low pathogenicity of this organism; however, it is noteworthy that immune suppression caused by management and/or corticoids treatment may induce parasitemia and anemia in this animal. This detection suggests further studies in captive wild cats in Brazilian Zoological Gardens.
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The objective of this study was to evaluate the larvicidal activity of diterpenoids obtained from the oil-resin of Copaifera reticulata against Aedes aegypti larvae, the principal vector of dengue and urban yellow fever. Four diterpenes were obtained from oil-resin extraction with organic solvents and subsequent chromatographic and spectroscopic procedures allowed to isolation and identification of these compounds as 3-b-acetoxylabdan-8(17)-13-dien-15-oic acid (1), alepterolic acid (2), 3-b-hidroxylabdan-8(17)-en-15-oic acid (3), and ent-agatic acid (4). Each compound was previously dissolved in dimethylsulphoxide, and distilled water was added to obtain the desired concentrations. Twenty larvae of third instars were placed into plastic beckers, containing the solution test (25 mL), in a five repetitions scheme, and their mortality, indicated by torpor and darkening of the cephalic capsule, was recorded after 48h. Probit analyses were used to determine lethal concentrations (LC50 and LC90) and their respective 95% confidence intervals. This study showed that only diterpenoids 1 and 2 exhibited larvicidal properties with LC50 of 0.8 ppm and 87.3 ppm, respectively, revealing the former as the most toxic compound against third instars of Ae. aegypti. Therefore, this compound seems to be an interesting source for new metabolite to be exploited.
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Trata-se de uma simples introdução aos problemas da inferência Bayesiana em que se procura estabelecer o confronto com a inferência clássica. Depois de referir o princípio clássico da amostragem repetida passa a considerar-se do ponto de vista Bayesiano os principais processos inferenciais tais como: estimação, intervalos de credibilidade, predição e ensaio de hipóteses.
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É apresentada uma introdução ao modelo de regressão linear do ponto de vista bayesiano. Para este feito, considera-se o modelo de regressão linear simples, introduzindo-se a hipótese simplificadora de que o parâmetro σ² (variância dos erros) é conhecido. São analisados os casos em que a distribuição a priori é não informativa e em que a distribuição a priori é conjugada (informativa). Por último, e com o objectivo de ilustrar os conceitos e as metodologias referidas, é apresentado um exemplo.
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Um dos problemas mais importantes da Estatística, pelo menos no que respeita às aplicações é sem dúvida o de predizer o futuro com base no resultado de experiência passada. Estranhamente no entanto, este problema não tem merecido, da parte dos Estatísticos, a atenção que se adivinharia da sua importância. Desenvolvimentos de metodologia Estatística têm-se centrado essencialmente em aspectos paramétricos e de modelação, sendo o problema da predição relegado para segundo plano, considerando talvez como mero “aparte”. O objectivo deste trabalho é precisamente o de fazer um pouco a história do problema da previsão estatística, apresentar a abordagem Bayesiana através de exemplos simples, fazendo um paralelo com soluções clássicas recentes.