análise experimental do efeito da diversificação em carteiras de ações: a relação entre risco e quantidade de ativos sob a ótica da estratégia ingênua

The objective is to analyze the relationship between risk and number of stocks of a portfolio for an individual investor when stocks are chosen by "naive strategy". For this, we carried out an experiment in which individuals select actions to reproduce this relationship. 126 participants were informed that the risk of first choice would be an asset average of all standard deviations of the portfolios consist of a single asset, and the same procedure should be used for portfolios composed of two, three and so on, up to 30 actions . They selected the assets they want in their portfolios without the support of a financial analysis. For comparison we also tested a hypothetical simulation of 126 investors who selected shares the same universe, through a random number generator. Thus, each real participant is compensated for random hypothetical investor facing the same opportunity. Patterns were observed in the portfolios of individual participants, characterizing the curves for the components of the samples. Because these groupings are somewhat arbitrary, it was used a more objective measure of behavior: a simple linear regression for each participant, in order to predict the variance of the portfolio depending on the number of assets. In addition, we conducted a pooled regression on all observations by analyzing cross-section. The result of pattern occurs on average but not for most individuals, many of which effectively "de-diversify" when adding seemingly random bonds. Furthermore, the results are slightly worse using a random number generator. This finding challenges the belief that only a small number of titles is necessary for diversification and shows that there is only applicable to a large sample. The implications are important since many individual investors holding few stocks in their portfolios

Determinantes genéticos da hanseníase em uma população do Rio Grande do Norte

Background: Leprosy can cause severe disability and disfigurement and is still a major health in different parts of the world. Only a subset of those individuals exposed to the pathogen will go on to develop clinical disease and there is a broad clinical spectrum amongst leprosy patients. The outcome of infection is in part due to host genes that influence control of the initial infection and the host´s immune response to that infection. Aim: Evaluate if polymorphisms type SNP in the 17q118q21 chromosomic region contribute to development of leprosy in Rio Grande do Norte population. Material and methods: A sample composed of 215 leprosy patients and 229 controls drawn from the same population were genotyped by using a Snapshot assay for eight genes (NOS2A, CCL18, CRLF3, CCL23, TNFAIP1, STAT5B, CCR7 and CSF3) located in chromosomic region 17q118q21. The genotype and allele frequency were measured and statistical analysis was performed by chi-square in SPSS version 15 and graph prism pad version 4 software. Results: Ours results indicated that the markers NOS2A8277, NOS2A8rs16949, CCR78rs11574663 and CSF38rs2227322 presented strong association with leprosy and their risk genotype were GG, TT, AA and GG respectively. The risk genotypes for all markers associated to leprosy presented recessive inheritance standard. When we compared the interaction among the markers in different combination we find that the marker NOS2A8277 associated with CCR78rs11574663 presented highest risk probability to development of leprosy. When we evaluated the haplotype of the risk markers it was found a haplotype associated with increase of the protection (CSF38rs22273228CC, CCR78 rs115746638GA, NOS2A8rs169498CT and NOS2A82778GA). The association of the clinical forms paucibacilary and multibacilary with markers showed that to the markers NOS2A8 2778GG, CCR78rs115746638AA and CSF38rs22273228GG there were a strong influence to migration to multibacilary pole and to marker NOS2A8rs169498TT the high proportion was found to the paucibacilary form. Conclusions: Changes in the genes NOS2A, CCR7 and CSF3 can influence the immune response against Mycobacterium leprae. The combination among these polymorphisms alters the risk probability to develop leprosy. The markers type SNP associated to development of the leprosy also are linked to clinical forms and its severity being the polymorphism NOS2A8rs169498TT associated with paucibacilar form and the polymorphisms NOS2A82778GG, CCR78rs115746638AA and CSF38rs22273228GG associated to multibacilar form

Predição em modelos de tempo de falha acelerado com efeito aleatório para avaliação de riscos de falha em poços petrolíferos

We considered prediction techniques based on models of accelerated failure time with random e ects for correlated survival data. Besides the bayesian approach through empirical Bayes estimator, we also discussed about the use of a classical predictor, the Empirical Best Linear Unbiased Predictor (EBLUP). In order to illustrate the use of these predictors, we considered applications on a real data set coming from the oil industry. More speci - cally, the data set involves the mean time between failure of petroleum-well equipments of the Bacia Potiguar. The goal of this study is to predict the risk/probability of failure in order to help a preventive maintenance program. The results show that both methods are suitable to predict future failures, providing good decisions in relation to employment and economy of resources for preventive maintenance.

Análise experimental do efeito da diversificação em carteiras de ações: a relação entre risco e quantidade de ativos sob a ótica da estratégia ingênua

The objective is to analyze the relationship between risk and number of stocks of a portfolio for an individual investor when stocks are chosen by "naive strategy". For this, we carried out an experiment in which individuals select actions to reproduce this relationship. 126 participants were informed that the risk of first choice would be an asset average of all standard deviations of the portfolios consist of a single asset, and the same procedure should be used for portfolios composed of two, three and so on, up to 30 actions . They selected the assets they want in their portfolios without the support of a financial analysis. For comparison we also tested a hypothetical simulation of 126 investors who selected shares the same universe, through a random number generator. Thus, each real participant is compensated for random hypothetical investor facing the same opportunity. Patterns were observed in the portfolios of individual participants, characterizing the curves for the components of the samples. Because these groupings are somewhat arbitrary, it was used a more objective measure of behavior: a simple linear regression for each participant, in order to predict the variance of the portfolio depending on the number of assets. In addition, we conducted a pooled regression on all observations by analyzing cross-section. The result of pattern occurs on average but not for most individuals, many of which effectively "de-diversify" when adding seemingly random bonds. Furthermore, the results are slightly worse using a random number generator. This finding challenges the belief that only a small number of titles is necessary for diversification and shows that there is only applicable to a large sample. The implications are important since many individual investors holding few stocks in their portfolios

Determinantes genéticos da hanseníase em uma população do Rio Grande do Norte

Background: Leprosy can cause severe disability and disfigurement and is still a major health in different parts of the world. Only a subset of those individuals exposed to the pathogen will go on to develop clinical disease and there is a broad clinical spectrum amongst leprosy patients. The outcome of infection is in part due to host genes that influence control of the initial infection and the host´s immune response to that infection. Aim: Evaluate if polymorphisms type SNP in the 17q118q21 chromosomic region contribute to development of leprosy in Rio Grande do Norte population. Material and methods: A sample composed of 215 leprosy patients and 229 controls drawn from the same population were genotyped by using a Snapshot assay for eight genes (NOS2A, CCL18, CRLF3, CCL23, TNFAIP1, STAT5B, CCR7 and CSF3) located in chromosomic region 17q118q21. The genotype and allele frequency were measured and statistical analysis was performed by chi-square in SPSS version 15 and graph prism pad version 4 software. Results: Ours results indicated that the markers NOS2A8277, NOS2A8rs16949, CCR78rs11574663 and CSF38rs2227322 presented strong association with leprosy and their risk genotype were GG, TT, AA and GG respectively. The risk genotypes for all markers associated to leprosy presented recessive inheritance standard. When we compared the interaction among the markers in different combination we find that the marker NOS2A8277 associated with CCR78rs11574663 presented highest risk probability to development of leprosy. When we evaluated the haplotype of the risk markers it was found a haplotype associated with increase of the protection (CSF38rs22273228CC, CCR78 rs115746638GA, NOS2A8rs169498CT and NOS2A82778GA). The association of the clinical forms paucibacilary and multibacilary with markers showed that to the markers NOS2A8 2778GG, CCR78rs115746638AA and CSF38rs22273228GG there were a strong influence to migration to multibacilary pole and to marker NOS2A8rs169498TT the high proportion was found to the paucibacilary form. Conclusions: Changes in the genes NOS2A, CCR7 and CSF3 can influence the immune response against Mycobacterium leprae. The combination among these polymorphisms alters the risk probability to develop leprosy. The markers type SNP associated to development of the leprosy also are linked to clinical forms and its severity being the polymorphism NOS2A8rs169498TT associated with paucibacilar form and the polymorphisms NOS2A82778GG, CCR78rs115746638AA and CSF38rs22273228GG associated to multibacilar form

Síndrome metabólica e fatores associados: estudo comparativo com mulheres que apresentaram pré-eclâmpsia e gravidez normal, acompanhadas cinco anos após o parto

Preeclampsia is defined as an extremely serious complication of the pregnancy-puerperium cycle with delayed emergence of cardiovascular risk factors, including metabolic syndrome. The research aimed estimate the prevalences of metabolic syndrome and associated factors in women with preeclampsia and normal pregnancy followed five years after childbirth. This is a cross-sectional observational study using a quantitative approach, conducted at a maternity school in the city of Natal in Rio Grande do Norte state. The sample was composed of 70 women with previous preeclampsia and 75 normal selected by simple random probability sampling. Subjects were analyzed for sociodemographic, obstetric, clinical, anthropometric and biochemical parameters. International Diabetes Federation criteria were adopted to diagnose metabol ic syndrome. The Kolmogorov-Smirnov, Mann-Whitney, Student s t, Pearson s chi-squared, and Fisher s exact tests, in addition to simple logistic regression, were used for data analysis, at a 5% significance level (p ≤ 0.05). Statistical tests demonstrated elevated body mass index (p = 0.001), predominance of family history of diabetes mellitus (p = 0.022) and significantly higher prevalence of metabolic syndrome in the preeclampsia group (37.1%) when compared to normal (22.7%) (p = 0.042). Intergroup comparison showed a high number of metabolic syndrome components in women with previous preeclampsia. Altered systolic and diastolic blood pressure (p < 0.001) was the most prevalent, followed by low concentrations of high-density lipoproteins (p = 0.049), and hyperglycemia (p=0.030). There was a predominance of the metabolic syndrome in women with schooling 0-9 years (42.4%) (p = 0.005), body mass index above 30Kg.m 2 (52.3%) (p < 0.001), uric acid high (62.5%) (p = 0.050 and family history of hypertension (38.5%) (p< 0.001). Multivariate analysis of the data showed that the body mass index above 30 kg.m2, education level less than 10 years of study (p < 0.001) and family history of hypertension (p = 0.002) remained associated with the metabolic syndrome after multivariate analysis of the data. It is considered Women with previous preeclampsia exhibited high prevalence of metabolic syndrome and their individual components in relation to normal, especially, altered systolic and diastolic blood pressure, low concentrations of high-density lipoproteins and hyperglycemia. The factors associated to this ou tcome were obesity, less than 10 years of schooling, and family history of hypertension. Overall, this study identified young women with a history of PE exposed to a higher cardiovascular risk than normal

Enfermagem na atenção primária em saúde no screening de adolescentes com excesso de peso

One of the Primary Health Care strategies for adolescent health is the growth and development follow-up and the early detection of overweight adolescents. Even though the School Health Program in Brazil proposes to evaluate the nutritional state of the school population in the corresponding community health units, not all cities have adhered to the Program and many nurses do not recognize overweight as a problem in their territory. The objective of the study was to identify the nurse´s participation in the screening of overweight adolescent students in their work territory. Cross sectional study conducted in eight state supported schools of the municipality of Natal/RN and in four Primary Health Units. The total student population was 27.277. A stratified sample was statistically calculated based on the student population of the four city geographical zones: 112 North , 74 West; 108 East; and 78 South, totalizing 372 adolescents. The students were selected by a probability process where eight schools were first selected, two per district, until the number per subsample in each district was reached. Four primary health nurses, responsible for the health units were included. Two instruments were used for data collection, a screening questionnaire and a semi-structured interview form for questioning of the nurses. The content of both instruments was validated. Anthropometric and health data were collected from the students and analyzed with descriptive and analytical statistics. Interview data were transcribed and submitted to content analysis. The nursing diagnosis of overweight was identified in 50 (13,5%) of the adolescents and its association with consumption of foods that have cardiovascular risk (canned foods, pasta and fried food). An association of the nursing diagnosis was identified with family history (diabetes, hypertension, obesity, and kidney disease). The nurses judged that care of overweight adolescents was important but noted difficulties because of the absence of this population in the health units, because of their work overload, and the lack of school articulation. The nurses do not have impacting actions with this population and delegate the responsibility to other professionals. It is concluded that overweight is a nutritional problem relevant to the adolescent school population in Natal/RN, with a 13,5% prevalence and that it is related to food consumption with cardiovascular risk and family health history. The nurses consider overweight as an important public health problem but do not envision ways to maintain linkage with adolescents and with the school to promote the needed care