996 resultados para Variable frequency oscillators
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As it is widely known, in structural dynamic applications, ranging from structural coupling to model updating, the incompatibility between measured and simulated data is inevitable, due to the problem of coordinate incompleteness. Usually, the experimental data from conventional vibration testing is collected at a few translational degrees of freedom (DOF) due to applied forces, using hammer or shaker exciters, over a limited frequency range. Hence, one can only measure a portion of the receptance matrix, few columns, related to the forced DOFs, and rows, related to the measured DOFs. In contrast, by finite element modeling, one can obtain a full data set, both in terms of DOFs and identified modes. Over the years, several model reduction techniques have been proposed, as well as data expansion ones. However, the latter are significantly fewer and the demand for efficient techniques is still an issue. In this work, one proposes a technique for expanding measured frequency response functions (FRF) over the entire set of DOFs. This technique is based upon a modified Kidder's method and the principle of reciprocity, and it avoids the need for modal identification, as it uses the measured FRFs directly. In order to illustrate the performance of the proposed technique, a set of simulated experimental translational FRFs is taken as reference to estimate rotational FRFs, including those that are due to applied moments.
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A revision of literature was done with the objective of tracing an epidemiologic profile of neurocysticercosis (NCC) in Brazil. The prevalence was 0.12-9% in autopsies. The frequency was 0.03-7.5% in clinical series and 0.68-5.2% in seroepidemiological studies. The disease corresponds to 0.08-2.5% of admissions to general hospitals. Patient origin was rural in 30-63% of cases. The most involved age range (64-100%) was 11 to 60 years, with a predominance (22-67%) between 21 and 40 years. The male sex was the most affected (51-80%). In the severe forms there was a predominance of urban origin (53-62%) and of the female sex (53-75%). The period of hospitalization ranges from 1 to 254 days and 33 to 50% of patients suffer 1.7 ± 1.4 admissions. The clinical picture was variable, with a predominance of epileptic syndrome (22-92%) and intracranial hypertension (19-89%). Psychiatric manifestations were associated in 9-23% of patients. Lethality was 0.29% in terms of all diseases in general and 4.8-25.9% in terms of neurologic diseases. The asymptomatic form was detected in 6% of patients in clinical serie and in 48.5% of case from autopsies. The racemose form and ventricular localization also was observed as asymptomatic form. Among the patients with cutaneous cysticercosis 65% of them showed neurologic manifestations.
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The frequency of microorganisms identified in nosocomial infections at Unicamp University Hospital from 1987 to 1994 was analysed. The most common microorganism was S. aureus (20.9%), which was found in surgical wound, bloodstream and arterial-venous infections. In urinary tract infections (UTI), gram-negative rods (56.5%) and yeasts (9%) predominated. A. baumannii isolates were observed to have increased in the last three years. There was a gradual increase in the frequency of coagulase-negative staphylococci and A. baumannii in bloodstream infections but there wasnt any change in Candida sp
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In order to evaluate the distribution of dermatophytes in Porto Alegre, the capital of the state of Rio Grande do Sul, Brazil, they were isolated from the skin, hairs and nails samples and retrospectively analyzed from June 1981 to June 1995, in two different institutions in the city of Porto Alegre: (i) the Serviço de Micologia do Instituto de Pesquisas Biológicas Jandyr Maya Faillace, da Secretaria de Saúde e Meio Ambiente do Rio Grande do Sul which attends the low income population (low and middle classes) and, (ii) Laboratório Weinmann, a clinical pathology laboratory which attends predominantly the higher income population (middle and upper classes), both which attend in the metropolitan area of Porto Alegre. The dermatophyte predominance of Trichophyton rubrum was confirmed (55.33%) followed by T. mentagrophytes (21.46%). The data obtained were compared with the existing prevalence data which were collected in the interior of the state over a period of 32 years (1960-1992). T. verrucosum, T. simii, Microsporum persicolor, T. schöenleinii, M. nanum and M. cookei were isolated in the interior and have not been found in the capital so far. On the other side, T. violaceum was, isolated in the capital and has not been found in the interior so far.
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Proceedings Institute of Acoustics (UK); vol. 25, nº2, p. 72-78.
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Due to the lack of studies about neurocysticercosis in the South of Brazil, an investigation was conducted to determine the percentage of suspected cases of neurocysticercosis in computed tomography diagnoses in Santa Maria, RS, from January 1997 to December 1998. Of 6300 computed tomographies (CT) of the skull performed at the private Hospital de Caridade Astrogildo de Azevedo, 80, i.e., 1.27% were suspected of neurocysticercosis. Fifty were women (62.5%) and 30 were men (37.5%). The most frequent radiological manifestation indicating neurocysticercosis was the presence of calcifications (isolated or associated), with a 95% rate (76 cases), while the presence of hypodense lesions reached a 5% rate (4 cases). After routine analysis, each CT was evaluated again and the suspected cases were confirmed. The percentage of suspected cases of neurocysticercosis detected by CT in the present study carried out in Santa Maria was considered low (1.27%). This can be explained by the fact that tomography is not accessible to the economically underprivileged population of Santa Maria. We hope that the present study can alert the population and the professionals to the fact that neurocysticercosis is a more frequent disease than indicated by the few diagnoses made.
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BACKGROUND: Use of polyclonal anti-hepatitis B surface antigen immunoglobulin (HBIg) has been shown to reduce hepatitis B virus (HBV) recurrence after liver transplantation (LT) and to decrease the frequency of acute cellular rejection (ACR). However, the protective role of HBIg against ACR remains controversial, since HBV infection has been also associated with a lower incidence of ACR. AIM: To assess the relationship between HBIg immunoprophylaxis and the incidence of rejection after LT. METHODS: 260 patients (158 males, 43 ± 14 years old) submitted to LT were retrospectively evaluated and divided into three groups, according to the presence of HBsAg and the use of HBIg. Group I was comprised of HBsAg-positive patients (n = 12) that received HBIg for more than 6 months. Group II was comprised of HBsAg-positive patients that historically have not received HBIg or have been treated irregularly for less than 3 months (n = 10). Group III was composed of 238 HBsAg-negative subjects that have not received HBIg. RESULTS: HBIg-treated patients (group I) had significantly less ACR episodes, when compared to group II and III. No differences between groups II and III were observed. CONCLUSIONS: Long-term HBIg administration contributes independently to reduce the number of ACR episodes after LT.
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A utilização eficiente da energia é essencial para a competitividade económica de um país. Sendo a intensidade energética de Portugal elevada, onde a utilização de motores elétricos, absorve cerca de metade da energia elétrica consumida na indústria, a utilização de conversores eletrónicos de potência permite obter economias de energia. Nesta tese pretende-se controlar a velocidade e o posicionamento de um tapete rolante através da utilização de um conversor eletrónico de potência. Na fundamentação teórica são referidos os conceitos de variação da tensão e frequência, controle escalar e vetorial, modelação por largura de pulso (PWM) assim como a retificação e ondulação da tensão de um variador de velocidades. Na parte prática será utilizado um servo motor, controlado por um variador eletrónico de velocidades, para efetuar o referido projeto. É ainda objeto desta tese o estudo dos parâmetros fundamentais assim como a pesquisa dos parâmetros a utilizar para o desempenho pretendido.
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Considering the impact of cysticercosis on public health, especially the neurologic form of the disease, neurocysticercosis (NC), we studied the frequency of positivity of anti-Taenia solium cysticercus antibodies in serum samples from 1,863 inhabitants of Cássia dos Coqueiros, SP, a municipal district located 80 km from Ribeirão Preto, an area considered endemic for cysticercosis. The 1,863 samples were tested by enzyme linked immunosorbent assay (ELISA) using an antigenic extract from Taenia crassiceps vesicular fluid (Tcra). The reactive and inconclusive ELISA samples were tested by immunoblotting. Of the 459 samples submitted to immunoblotting, 40 were strongly immunoreactive to the immunodominant 18 and 14 kD peptides. Considering the use of immunoblotting as confirmatory due to its high specificity, the anti-cysticercus serum prevalence in this population was 2.1%.
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The most preferred containers by Aedes aegypti were studied April and July (rainy and dry periods) in two Manaus neighbourhoods. In all, 2,700 premises and 13,912 containers were examined, most (87%) recorded outdoors. Out of the 13,100 inspected premises, only 1.6% showed to be positive for Aedes aegypti, summing up to 7,916 collected samples. Most frequently found containers outdoors in either neighbourhood regardless of rain or dry period were Bottles flasks and Storage, and indoors, Fixed, Flowerpots, and buckets. Productivity was estimated according to the number of premises and positive containers investigated, showing the actual container groups productivity. Considering both rainy and dry periods outdoors at Praça 14 the groups of Tyre, Flask, Bottle, Construction Equipment and Fixed, had the highest averages respectively. Construction Equipment and Flask groups were the most productive in Coroado in April. Flask, Construction Equipment and Storage groups stood out in July.
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Hepatocellular carcinoma (HCC) is an important type of cancer etiologically related to some viruses, chemical carcinogens and other host or environmental factors associated to chronic liver injury in humans. The tumor suppressor gene p53 is mutated in highly variable levels (0-52%) of HCC in different countries. OBJECTIVE: The objective of the present study was to compare the frequency of aberrant immunohistochemical expression of p53 in HCC occurring in cirrhotic or in non-cirrhotic patients as well as in liver cell dysplasia and in adenomatous hyperplasia. We studied 84 patients with HCC or cirrhosis. RESULTS: We detected p53 altered immuno-expression in 58.3% of patients in Grade III-IV contrasting to 22.2% of patients in Grade I-II (p = 0.02). Nontumorous areas either in the vicinity of HCC or in the 30 purely cirrhotic cases showed no nuclear p53 altered expression, even in foci of dysplasia or adenomatous hyperplasia. No significant difference was found among cases related to HBV, HCV or alcohol. CONCLUSION: The high frequency of p53 immunoexpression in this population is closer to those reported in China and Africa, demanding further studies to explain the differences with European and North American reports.
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Parasitic infections caused by intestinal protozoan and helminths affect more than two billion people worldwide and chemotherapy is the most commonly used therapeutic procedure. Considering the problems created by parasitic infections and the incorrect use of drugs, the aim of this work was to detect the frequency of enteroparasites infection and to estimate the use of chemotherapeutic agents in children living in the periphery of the city of Porto Alegre, RS, Brazil. Ninety-six preschool age children, who had parasitological exams and who used antiparasitic drugs, were analyzed. The efficacy of treatment was evaluated by stool examination repeated six months after treatment. The same diagnostic test was used to evaluate parasitological cure, which was defined as absence of eggs and cysts in the stool. From these children, 79 (82.3%) were contaminated by some species of parasite, the most prevalent were Ascaris lumbricoides, Trichuris trichiura and Giardia lamblia. The most commonly used drugs were mebendazole (86% of prescriptions) and metronidazole (30.3%). The cure rate in the 79 children, examined 6 months after treatment, was 65.3% for A. lumbricoides and 66.1% for T. trichiura. This study suggests that a continuous education program regarding the prevention and treatment of parasitic infections is an essential tool for their eradication.
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In a transversal study on a sample of 386 children and adolescents from an outpatient clinic for filariasis in Recife, Northeast Brazil, the frequency of anti-Toxocara antibodies and its relation to age, gender, number of peripheral eosinophils, Wuchereria bancrofti microfilariae and intestinal helminths was determined. The total anti-Toxocara IgG antibody frequency was 39.4%, by ELISA technique. The difference in frequency between males (40.1%) and females (37.6%) was not statistically significant. The 6 to 10-year-old subset presented the highest frequency of anti-Toxocara antibodies (60%), and within this age group there was a statistically significant male bias. There was also a significant association between the number of eosinophils and the presence of anti-Toxocara antibodies. Intestinal parasite frequency was 52.1%, but no association was found between this data and the presence of anti-Toxocara antibodies. In the present sample, 42.2% of the patients were Wuchereria bancrofti carriers, however, again this was not associated with the presence of anti-Toxocara antibodies. In conclusion, anti-Toxocara antibodies were highly prevalent in this sample. The present data show that there is no cross correlation between anti-Toxocara IgG antibody and the presence of intestinal helminths and filariasis.