Search results for "Statistica"
showing 10 items of 5969 documents
The rise of the middle author: Investigating collaboration and division of labor in biomedical research using partial alphabetical authorship
2017
Contemporary biomedical research is performed by increasingly large teams. Consequently, an increasingly large number of individuals are being listed as authors in the bylines, which complicates the proper attribution of credit and responsibility to individual authors. Typically, more importance is given to the first and last authors, while it is assumed that the others (the middle authors) have made smaller contributions. However, this may not properly reflect the actual division of labor because some authors other than the first and last may have made major contributions. In practice, research teams may differentiate the main contributors from the rest by using partial alphabetical author…
Procedimento estratégico em três estágios de seleção de variáveis para a obtenção de resultados equilibrados na pesquisa em saúde pública
2018
Multidisciplinary research in public health is approached using methods from many scientific disciplines. One of the main characteristics of this type of research is dealing with large data sets. Classic statistical variable selection methods, known as “screen and clean”, and used in a single-step, select the variables with greater explanatory weight in the model. These methods, commonly used in public health research, may induce masking and multicollinearity, excluding relevant variables for the experts in each discipline and skewing the result. Some specific techniques are used to solve this problem, such as penalized regressions and Bayesian statistics, they offer more balanced results a…
Evaluating the effect of organization and context on technical efficiency: a second-stage DEA analysis of Italian hospitals
2022
Objective: the purpose of this study was to compare the technical efficiency of Italian hospitals at a regional level and to examine if differences could be explained by organisational and contextual factors. Technical efficiency was defined as the ability of the operating units evaluated to use optimal resource levels for their level of output.Methods: the effect of external factors was explored through a second stage Data Envelopment Analysis (DEA). Efficiency scores were calculated for each hospital using the DEA method (Stage I). Through Tobit regression analysis, the estimated efficiency scores were regressed against a set of organisational and contextual characteristics beyond manager…
Atypical Antipsychotics in the Treatment of Acute Bipolar Depression with Mixed Features: A Systematic Review and Exploratory Meta-Analysis of Placeb…
2016
Evidence supporting the use of second generation antipsychotics (SGAs) in the treatment of acute depression with mixed features (MFs) associated with bipolar disorder (BD) is scarce and equivocal. Therefore, we conducted a systematic review and preliminary meta-analysis investigating SGAs in the treatment of acute BD depression with MFs. Two authors independently searched major electronic databases from 1990 until September 2015 for randomized (placebo-) controlled trials (RCTs) or open-label clinical trials investigating the efficacy of SGAs in the treatment of acute bipolar depression with MFs. A random-effect meta-analysis calculating the standardized mean difference (SMD) between SGA an…
Factor analyses of multidimensional symptoms in a large group of patients with major depressive disorder, bipolar disorder, schizoaffective disorder …
2020
Abstract Background There is an ongoing discussion about which neurobiological correlates or symptoms separate the major psychoses (i.e. Major Depressive Disorder MDD, Bipolar Disorder BD, and Schizophrenia SZ). Psychopathological factor analyses within one of these disorders have resulted in models including one to five factors. Factor analyses across the major psychoses using a comprehensive set of psychopathological scales in the same patients are lacking. It is further unclear, whether hierarchical or unitarian models better summarize phenomena. Method Patients (n = 1182) who met DSM-IV criteria for MDD, BD, SZ or schizoaffective disorder were assessed with the SANS, SAPS, HAMA, HAM-D, …
Entanglement dynamics in superconducting qubits affected by local bistable impurities
2012
We study the entanglement dynamics for two independent superconducting qubits each affected by a bistable impurity generating random telegraph noise (RTN) at pure dephasing. The relevant parameter is the ratio $g$ between qubit-RTN coupling strength and RTN switching rate, that captures the physics of the crossover between Markovian and non-Markovian features of the dynamics. For identical qubit-RTN subsystems, a threshold value $g_\mathrm{th}$ of the crossover parameter separates exponential decay and onset of revivals; different qualitative behaviors also show up by changing the initial conditions of the RTN. We moreover show that, for different qubit-RTN subsystems, when both qubits are …
Host–virus evolutionary dynamics with specialist and generalist infection strategies: Bifurcations, bistability, and chaos
2019
In this work, we have investigated the evolutionary dynamics of a generalist pathogen, e.g., a virus population, that evolves toward specialization in an environment with multiple host types. We have particularly explored under which conditions generalist viral strains may rise in frequency and coexist with specialist strains or even dominate the population. By means of a nonlinear mathematical model and bifurcation analysis, we have determined the theoretical conditions for stability of nine identified equilibria and provided biological interpretation in terms of the infection rates for the viral specialist and generalist strains. By means of a stability diagram, we identified stable fixed…
A semi-parametric stochastic generator for bivariate extreme events
2017
The analysis of multiple extreme values aims to describe the stochastic behaviour of observations in the joint upper tail of a distribution function. For instance, being able to simulate multivariate extreme events is convenient for end users who need a large number of random replications of extremes as input of a given complex system to test its sensitivity. The simulation of multivariate extremes is often based on the assumption that the dependence structure, the so-called extremal dependence function, is described by a specific parametric model. We propose a simulation method for sampling bivariate extremes, under the assumption that the extremal dependence function is semiparametric. Th…
Six Sigma in small- and medium-sized enterprises: a Black Belt project in the Swedish steel industry
2014
Many big companies around the world have solid Six Sigma infrastructures and it is easy to find in literature successful case studies. Conversely, small and medium-sized enterprises (SMEs) generally suffer lower attention in the literature. This happens because SMEs have only recently approached the methodology; they have weaker connection with the academia; or they do not rigorously pursue the frameworks. This paper is based on a Six Sigma project in a Swedish medium-sized company that produces steel tubes mainly for hydraulic applications. The project focused on the improvement of warehouse activities related to cutting processes. This Black Belt project was part of a Six Sigma education …
Desaturase activities are depleted before and after weaning in liver microsomes of spontaneously hypertensive rats
2002
Abstract In the present study, we have investigated the microsomal linoleic acid desaturation steps into arachidonic acid in 10- and 30-day-old spontaneously hypertensive rats (SHR), as compared to their normotensive control rats, Wistar Kyoto (WKY). Suckled by adoptive Wistar normotensive female, the SHR and WKY were fed the same diet. Our results show lower Δ6 and Δ5 desaturase activities (the limiting steps in the bioconversion of linoleic acid into arachidonic acid) in the young SHR, as compared to the WKY normotensive rats. The fatty acid composition of liver microsomal total lipids evidences a higher proportion of linoleic acid in SHR than in WKY, in agreement with the partially deple…