901 resultados para Small sample asymptotics


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INTRODUCTION: Human cytomegalovirus is an opportunistic betaherpesvirus that causes persistent and serious infections in immunodeficient patients. Recurrent infections occur due to the presence of the virus in a latent state in some cell types. It is possible to examine the virus using molecular methods to aid in the immunological diagnosis and to generate a molecular viral profile in immunodeficient patients. The objective of this study was to characterize cytomegalovirus genotypes and to generate the epidemiological and molecular viral profile in immunodeficient patients. METHODS: A total of 105 samples were collected from immunodeficient patients from the City of Belém, including newborns, hemodialysis patients, transplant recipients and HIV+ patients. An IgG and IgM antibody study was completed using ELISA, and enzymatic analysis by restriction fragment length polymorphism (RFLP) was performed to characterize viral genotypes. RESULTS: It was observed that 100% of the patients had IgG antibodies, 87% of which were IgG+/IgM-, consistent with a prior infection profile, 13% were IgG+/IgM+, suggestive of recent infection. The newborn group had the highest frequency (27%) of the IgG+/IgM+ profile. By RFLP analysis, only one genotype was observed, gB2, which corresponded to the standard AD169 strain. CONCLUSIONS: The presence of IgM antibodies in new borns indicates that HCMV continues to be an important cause of congenital infection. The low observed genotypic diversity could be attributed to the small sample size because newborns were excluded from the RFLP analysis. This study will be continued including samples from newborns to extend the knowledge of the general and molecular epidemiology of HCMV in immunodeficient patients.

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A multilocus mixed-mating model was used to evaluate the mating system of a population of Couratari multiflora, an emergent tree species found in low densities (1 individual/10 ha) in lowland forests of central Amazonia. We surveyed and observed phenologically 41 trees in an area of 400 ha. From these, only four mother trees were analyzed here because few of them set fruits, which also suffered high predation. No difference was observed between the population multilocus outcrossing rate (t mp = 0.953 ± 0.040) and the average single locus rate (t sp = 0.968 ± 0.132). The four mother trees were highly outcrossed (t m ~ 1). Two out of five loci showed departures from the Hardy-Weinberg Equilibrium (HWE) expectations, and the same results occurred with the mixed-mating model. Besides the low number of trees analyzed, the proportion of loci in HWE suggests random mating in the population. However, the pollen pool was heterogeneous among families, probably due to both the small sample number and the flowering of trees at different times of the flowering season. Reproductive phenology of the population and the results presented here suggest, at least for part of the population, a long-distance pollen movement, around 1,000 m.

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Dissertação de mestrado em Optometria Avançada

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The Amazon tree boa Corallus hortulanus is known for featuring a wide variation in color pattern and design markings. Although there are studies on its polychromatism, none of them addresses the geographic variation in the color pattern of this species. The aim of this study was to describe the chromatic variation found in the populations of C. hortulanus from the southern Amazon Basin and its relationship with geographic distribution of the species. Analysis of both design markings and color patterns on 112 C. hortulanus specimens from the southern Amazon Basin interfluves resulted in the identification of six distinct morphotypes. Grayish-brown coloration and elongated diamond-shaped patterns were the most frequent patterns. Two morphotypes showed a tendency of correlation with the geographical distribution of those species found in Madeira and Juruá Rivers. The small sample size does not allow for a robust conclusion on the possible cause of geographic variation. The distribution of morphological patterns of C. hortullanus in the Amazon Basin suggest that there is gene flow between populations, regardless of geographical distance and natural barriers. The variation in color pattern and markings may represent a phenotypic response to the characteristics of different habitats occupied by the species.

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OBJECTIVE: To study the long-term follow-up of patients with bipolar disorder (BPD). METHOD: Eleven outpatients with BPD type I were followed up naturalistically for five years at a university teaching hospital. The Clinical Global Impression Scale (BPD version) was used to evaluate the occurrence of affective episodes, and the Strauss-Carpenter Outcome Scale was used to evaluate social and occupational functioning. RESULTS: The majority of patients were symptomatic most of the time, with predominantly depressive episodes. Overall, patients remained euthymic a mean of 47.7% of the time. Despite a low rate of hospitalization, social and occupational functioning was poor in the majority of patients. A poor disease course with respect to work-related functioning was associated with fewer months of euthymia with a longer duration of depressive episodes. The total number of months of euthymia negatively correlated with the patient's age and disease duration. CONCLUSION: Despite the small sample size, the present findings appear to corroborate previous studies on the evolution of BPD. Most of the patients had a poor disease course, with long symptomatic periods, particularly depressive episodes, and significantly impaired social and occupational functioning.

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Background:Several studies have shown that Tai Chi Chuan can improve cardiac function in patients with heart disease.Objective:To conduct a systematic review of the literature to assess the effects of Tai Chi Chuan on cardiac rehabilitation for patients with coronary artery disease.Methods:We performed a search for studies published in English, Portuguese and Spanish in the following databases: MEDLINE, EMBASE, LILACS and Cochrane Register of Controlled Trials. Data were extracted in a standardized manner by three independent investigators, who were responsible for assessing the methodological quality of the manuscripts.Results:The initial search found 201 studies that, after review of titles and abstracts, resulted in a selection of 12 manuscripts. They were fully analyzed and of these, nine were excluded. As a final result, three randomized controlled trials remained. The studies analyzed in this systematic review included patients with a confirmed diagnosis of coronary artery disease, all were clinically stable and able to exercise. The three experiments had a control group that practiced structured exercise training or received counseling for exercise. Follow-up ranged from 2 to 12 months.Conclusion:Preliminary evidence suggests that Tai Chi Chuan can be an unconventional form of cardiac rehabilitation, being an adjunctive therapy in the treatment of patients with stable coronary artery disease. However, the methodological quality of the included articles and the small sample sizes clearly indicate that new randomized controlled trials are needed in this regard.

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This study has been carried out at the central region of the Araguaia river on the border between the states of Goiás and Mato Grosso in the Brazilian Amazon Basin from September to December 2000. We recorded temperature fluctuation, clutch-size, incubation period and hatching success rate and hatchlings' sex ratio of five nests of Podocnemis expansa (Schweigger, 1812). Despite the relatively small sample size we infer that: a) nests of P. expansa in the central Araguaia river have a lower incubation temperature than nests located further south; however, incubation period is shorter, hatching success rate is lower and clutch-size is larger; b) Podocnemis expansa may present a female-male-female (FMF) pattern of temperature sex-determination (TSD); c) thermosensitive period of sex determination apparently occur at the last third of the incubation period; and, d) future studies should prioritize the relationship between temperature variation (i.e., range and cycle) and embryos development, survivorship and sex determination.

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Regular stair climbing has well-documented health dividends, such as increased fitness and strength, weight loss and reduced body fat, improved lipid profiles and reduced risk of osteoporosis. The general absence of barriers to participation makes stair climbing an ideal physical activity (PA) for health promotion. Studies in the US and the UK have consistently shown that interventions to increase the accumulation of lifestyle PA by climbing stairs rather than using the escalators are effective. However, there are no previous in Catalonia. This project tested one message for their ability to prompt travelers on the Montjuïc site to choose the stairs rather than the escalator when climbing up the Monjuïc hill. One standard message, " Take the stairs! 7 minutes of stair climbing a day protects your heart" provided a comparison with previous research done in the UK. Translated into Catalan and Spanish, it was presented on a poster positioned at the point of choice between the stairs and the escalator. The study used a quasi-experimental, interrupted time series design. Travelers, during several and specific hours on two days of the week, were coded for stair or escalator use, gender, age, ethnic status, presence of accompanying children or bags by one observer. Overall, the intervention resulted in a 81% increase in stair climbing. In the follow-up period without messages, stair climbing dropped out to baseline levels. This preliminary study showed a significant effect on stair use. However, caution is needed since results are based on a small sample and, only a low percentage of the sample took the stairs at baseline or the intervention phase . Future research on stair use in Catalonia should focus on using bigger samples, different sites (metro stations, airports, shopping centers, etc) , different messages and techniques to promote stair climbing.

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During an outbreak of cutaneous leishmaniasis in a locality (Las Rosas, Cojedes State, venezuela) previously non-endemic, 12.9% of humans, 7% of dogs and 21.4% of donkeys (Equus asinus) had lesions with paraites. The agent in the three hosts was identified as Leishmania braziliensis, subspecies braziliensis at least in man and donkey. The probable vector was Lutzomyia panamensis. No infection was found in a small sample of wild mammals examined. The outbreak was apparently linked with the importation of donkeys with ulcers, from endemic areas. The Authors call attention to the fact that not only in the foci of "uta", but also in areas of the other forms of American cutaneous leishmaniasis, dogs are frequently found infected. They emphasize the necessity of searching for the infection in donkeys and of performing hemocultures and xenodiagnosis with sandflies in human, canine and equine cases, to verify their possible role as sources of infection, and not merely as dead ends in the epidemiological chain of the disease.

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Introduction: Renal transplantation is considered the treatment of choice for end-stage renal disease. However, the association of occlusive aorto-iliac disease and chronic renal failure is frequent and aorto-iliac reconstruction may be necessary prior to renal transplantation. This retrospective study reviews the results of this operative strategy.Material and Methods: Between January 2001 and June 2010, 309 patients underwent renal transplantation at our institution and 8 patients had prior aorto-iliac reconstruction using prosthetic material. There were 6 men and 2 women with a median age of 62 years (range 51-70). Five aorto-bifemoral and 2 aorto-bi-iliac bypasses were performed for stage II (n=5), stage IV (n=1) and aortic aneurysm (n=1). In one patient, iliac kissing stents and an ilio-femoral bypass were implanted. 4 cadaveric and 4 living donor renal transplantations were performed with an interval of 2 months to 10 years after revascularization.The results were analysed with respect of graft and patients survival. Differences between groups were tested by the log rank method.Results: No complications and no death occurred in the post-operative period. All bypasses remained patent during follow-up. The median time of post transplantation follow-up was 46 months for all patients and 27 months for patients with prior revascularization. In the revascularized group and control group, the graft and patient survival at 1 year were respectively 100%/96%, 100%/99% and at 5 years 86%/86%, 86%/94%, without significant differences between both groups.Discussion: Our results suggest that renal transplantation following prior aorto-iliac revascularisation with prosthetic material is safe and effective. Patients with end-stage renal disease and concomitant aorto-iliac disease should therefore be considered for renal transplantation. However, caution in the interpretation of the results is indicated due to the small sample size of our study.

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We examine the long run relationship between stock prices and goods prices to gauge whether stock market investment can hedge against inflation. Data from sixteen OECD countries over the period 1970-2006 are used. We account for different inflation regimes with the use of sub-sample regressions, whilst maintaining the power of tests in small sample sizes by combining time-series data across our sample countries in a panel unit root and panel cointegration econometric framework. The evidence supports a positive long-run relationship between goods prices and stock prices with the estimated goods price coefficient being in line with the generalized Fisher hypothesis.

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We develop tests of the proportional hazards assumption, with respect to a continuous covariate, in the presence of unobserved heterogeneity with unknown distribution at the individual observation level. The proposed tests are specially powerful against ordered alternatives useful for modeling non-proportional hazards situations. By contrast to the case when the heterogeneity distribution is known up to …nite dimensional parameters, the null hypothesis for the current problem is similar to a test for absence of covariate dependence. However, the two testing problems di¤er in the nature of relevant alternative hypotheses. We develop tests for both the problems against ordered alternatives. Small sample performance and an application to real data highlight the usefulness of the framework and methodology.

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Consider a model with parameter phi, and an auxiliary model with parameter theta. Let phi be a randomly sampled from a given density over the known parameter space. Monte Carlo methods can be used to draw simulated data and compute the corresponding estimate of theta, say theta_tilde. A large set of tuples (phi, theta_tilde) can be generated in this manner. Nonparametric methods may be use to fit the function E(phi|theta_tilde=a), using these tuples. It is proposed to estimate phi using the fitted E(phi|theta_tilde=theta_hat), where theta_hat is the auxiliary estimate, using the real sample data. This is a consistent and asymptotically normally distributed estimator, under certain assumptions. Monte Carlo results for dynamic panel data and vector autoregressions show that this estimator can have very attractive small sample properties. Confidence intervals can be constructed using the quantiles of the phi for which theta_tilde is close to theta_hat. Such confidence intervals are found to have very accurate coverage.

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De l’experiència professional de l’equip del SATAF al llarg dels anys, s’ha constatat que un dels conflictes més recurrents, existents en els procediments contenciosos, és el rebuig filial envers un dels progenitors, habitualment, el no-custodi. Un tipus de rebuig filial és la Síndrome d’Alienació Parental (SAP), descrita per Gardner, inicialment, l’any 1985. A partir dels estudis realitzats d’ençà l’any 2004, aquest grup d’investigació pretén centrar la present recerca en el perfil de competències parentals del progenitor alienat. Paral·lelament, s’ha elaborat una entrevista semiestructurada d’exploració de la SAP. Altrament, també s’ha creat una guia d’observadors per tal d’aconseguir certa operativitat diagnòstica. Els resultats obtinguts han partit d’una anàlisis estadística no-paramètrica, considerant el petit tamany de la mostra. Amb l’anàlisi, es constata que la gravetat de la SAP no manté relació quant a presència d’habilitats parentals en el progenitor alienat. D'altra banda, l’actitud d’aquests progenitors incideix en el manteniment de la Síndrome. Disposar d’eines específiques per a l’avaluació d’aquests casos optimitza i operatitvitza les intervencions amb aquestes famílies.

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Species-specific Random Amplified Polymorphic DNA-Polymerase chain Reaction (RAPD-PCR) markers were used to identify four species related to Anopheles (Nyssorhynchus) albitarsis Lynch-Arribàlzaga from 12 sites in Brazil and 4 in Venezuela. In a previous study (Wilkerson et al. 1995), which included sites in Paraguay and Argentina, these four species were designated "A", "B", "C" and "D". It was hypothesized that species A is An. (Nys.) albitarsis, species B is undescribed, species C is An. (Nys) marajoara Galvão and Damasceno and species D is An. (Nys.) deaneorum Rosa-Freitas. Species D, previously characterized by RAPD-PCR from a small sample from northern Argentina and southern Brazil, is reported here from the type locality of An. (Nys.) deaneorum, Guajará-Mirim, state of Rondônia, Brazil. Species C and D were found by RAPD-PCR to be sympatric at Costa Marques, state of Rondônia, Brazil. Species A and C have yet to be encountered at the same locality. The RAPD markers for species C were found to be conserved over 4,620 km; from Iguape, state of São Paulo, Brazil to rio Socuavo, state of Zulia, Venezuela. RAPD-PCR was determined to be an effective means for the identification of unknown species within this species complex.