Toward a more structured use of information technology in the research community

Information technology has great potential for supporting the activities of research networks. However, some fundamental problems must first be addressed to determine whether the technological support is necessary at all. Once that need has been determined, merely installing a set of isolated, generic information tools is not sufficient to address the full spectrum of network information needs. Therefore, a comprehensive and customized network information system is required. We argue that a specification method can help to structure the development of such an information system. Aldo de Moor finished his M.Sc. in information management in 1993, after which he worked at the University of Guelph, Canada, on the initiation of the Global Research Network on Sustainable Development. He is currently pursuing his Ph.D. at Tilburg University.     

Bayesian analysis of censored linear regression models with scale mixtures of normal distributions

As is the case of many studies, the data collected are limited and an exact value is recorded only if it falls within an interval range. Hence, the responses can be either left, interval or right censored. Linear (and nonlinear) regression models are routinely used to analyze these types of data and are based on normality assumptions for the errors terms. However, those analyzes might not provide robust inference when the normality assumptions are questionable. In this article, we develop a Bayesian framework for censored linear regression models by replacing the Gaussian assumptions for the random errors with scale mixtures of normal (SMN) distributions. The SMN is an attractive class of symmetric heavy-tailed densities that includes the normal, Student-t, Pearson type VII, slash and the contaminated normal distributions, as special cases. Using a Bayesian paradigm, an efficient Markov chain Monte Carlo algorithm is introduced to carry out posterior inference. A new hierarchical prior distribution is suggested for the degrees of freedom parameter in the Student-t distribution. The likelihood function is utilized to compute not only some Bayesian model selection measures but also to develop Bayesian case-deletion influence diagnostics based on the q-divergence measure. The proposed Bayesian methods are implemented in the R package BayesCR. The newly developed procedures are illustrated with applications using real and simulated data.     

Late-onset hypogonadism: the advantages of treatment with human chorionic gonadotropin rather than testosterone

The traditional pharmacological treatment of patients with late onset hypogonadism (LOH) is represented by different formulations of testosterone (T) or alternatively by the extractive human chorionic gonadotropin (HCG). The hormone replacement treatment (HRT) is associated with the potential increase of hematocrit, serum concentrations of prostate-specific antigen (PSA) and prostate volume. Moreover, the gynecomastia represent a condition frequently associated with HRT. Recent evidences showed the role of leydig cells in the 25-hydroxylation of vitamin D and the elevated frequency of hypovitaminosis D among LOH patients. Finally, another important aspect of LOH is represented by the frequency of secondary infertility due to age or to traditional HRT. This study evaluated 40 LOH patients treated for 6 months with extractive HCG (n?=?10 patients) and three different formulations of T: transdermal (n?=?10 patients), undecaonate (n?=?10 patients) and enantate (n?=?10 patients). Hormonal, anthropometric, metabolic and sperm parameters were evaluated and compared. Moreover, the main safety parameters and the results of the main questionnaires were evaluated. After treatment, HCG group showed serum concentrations of 25-OH-vitamin D significantly higher (p?p?p?p?相似文献   

Epidemiology and risk factors of lower urinary tract symptoms/benign prostatic hyperplasia and erectile dysfunction

Benign prostatic hyperplasia (BPH) is very common in aging men and causes lower urinary tract symptoms (LUTS), which decrease health-related quality of life. A number of evidence suggests that other than ageing, modifiable factors, such as increasing prostate volume, obesity, diet, dyslipidemia, hormonal imbalance, hypertension, metabolic syndrome, alcohol, and smoking, also contribute to the development of BPH and/or LUTS. More recently, erectile dysfunction (ED) has been linked to LUTS/BPH as a part of this syndrome, suggesting that patients with BPH or LUTS easily develop ED, and that LUTS/BPH symptoms often coexist with ED. This article focuses on the epidemiology and risk factors of the combined phenotype LUTS/BPH – ED.     

Conditional inference under simultaneous stochastic ordering constraints

Testing for stochastic ordering is of considerable importance when increasing does of a treatment are being compared, but in applications involving multivariate responses has received much less attention. We propose a permutation test for testing against multivariate stochastic ordering. This test is distribution-free and no assumption is made about the dependence relations among variables. A comparative simulation study shows that the proposed solution exhibits a good overall performance when compared with existing tests that can be used for the same problem.