Search results for " homogeneity."
showing 10 items of 13 documents
Physical activity and aerobic fitness in relation to local and interhemispheric functional connectivity in adolescents' brains
2021
Abstract Introduction Adolescents have experienced decreased aerobic fitness levels and insufficient physical activity levels over the past decades. While both physical activity and aerobic fitness are related to physical and mental health, little is known concerning how they manifest in the brain during this stage of development, characterized by significant physical and psychosocial changes. The aim of the study is to examine the associations between both physical activity and aerobic fitness with brains’ functional connectivity. Methods Here, we examined how physical activity and aerobic fitness are associated with local and interhemispheric functional connectivity of the adolescent brai…
Demographic and behavioural profiles of patients with common oral mucosal lesions by a homogeneity analysis
2012
Objective: The aim of this study is to assess the main oral mucosal lesions (OMLs) within a hospital base and to provide an anamnestic, diagnostic model based on homogeneity analysis of some variables. Methods: The demographic and behavioural data (i.e. gender, age, smoking status, alcohol consumption and therapeutic drug usage) of 1753 patients with at least one OML were considered. Multiple correspondence analysis (MCA) and multivariate tests of the simultaneous marginal homogeneity hypothesis (SMH) were used to analyse the evidence of any differences between the demographic and behavioural profiles relating to OMLs diagnoses. Statistical significance of P<0.05 was chosen. Results: With r…
Overview of Prognostic Systems for Hepatocellular Carcinoma and ITA.LI.CA External Validation of MESH and CNLC Classifications
2021
Simple Summary This review proposes a comprehensive overview of the main prognostic systems for HCC classified as prognostic scores, staging systems, or combined systems. Prognostic systems for HCC are usually compared in terms of homogeneity, monotonicity of gradients, and discrimination ability. However, despite the great number of published studies comparing HCC prognostic systems, it is rather difficult to identify a system that could be universally accepted as the best prognostic scheme for all HCC patients encountered in clinical practice. In order to give a contribute in this topic, we conducted a study aimed at externally validate the MESH score and the CNLC classification using the…
Using proximity and spatial homogeneity in neighbourhood-based classifiers
1997
In this paper, a set of neighbourhood-based classifiers are jointly used in order to select a more reliable neighbourhood of a given sample and take an appropriate decision about its class membership. The approaches introduced here make use of two concepts: proximity and symmetric placement of the samples.
Measuring the Spatial Homogeneity in Corneal Endotheliums by Means of a Randomization Test
1999
Quantification of regularity of cell sizes and the spatial arrangement of cells in corneal endotheliums becomes of a great importance associated to stress situations such as cataract surgery, corneal transplantation or implantation of intra-ocular lenses. A new index of regularity of the spatial distribution of cell sizes in corneal endotheliums is proposed. The corneal endothelium is described by means of a spatial marked point pattern (the cell centroids marked with the cell areas). The hypothesis of no dependency between mark and locations is tested by a Monte Carlo test. The new index is the p-value of the test validating the hypothesis. Pairs of endotheliums from different eyes of the …
The problem of spatial homogeneity in an LCoS projector
2019
Abstract Video projectors allow interesting applications in vision sciences since they provide a large projection area. We have colorimetrically characterized a LCoS projector using a mathematical model requiring additivity and constancy of the primaries -a sigmoid function in our case. Significant differences in chromaticity in the CIELAB space, but not in lightness, were found between the center and the corners of the screen. The lack of spatial homogeneity led us to estimate the parameters of the model as a function of spatial position, using different strategies. The best result was obtained by interpolating the values of the parameters of the model determined from experimental measurem…
Modelling of Boltzmann transport equation for freeze-out
2005
The freeze-out (FO) in high-energy heavy-ion collisions is assumed to be continuous across finite layer in space–time. Particles leaving local thermal equilibrium start to freeze out gradually till they leave the layer, where all the particles are frozen out. To describe such a kinetic process we start from Boltzmann transport equation (BTE). However, we will show that the basic assumptions of BTE, such as molecular chaos or spatial homogeneity do not hold for the above-mentioned FO process. The aim of the presented work is to analyse the situation, discuss the modification of BTE and point out the physical causes, which yield to these modifications of BTE for describing FO.
Coil homogeneity and the effect of rotor filling on the spectral resolution
2009
Spectral resolution depends upon the length (N) of the transform interval: N=F/ f, where f is the smallest frequency difference which can be distinguished at a given sampling frequency F. f depends on the signal width, which, in turn, is influenced by the relaxation time of the sampled signal. Relaxation time is affected by the external magnetic field and the applied pulse sent to the sample through the transmitter/receiver coil. The pulse length homogeneity throughout this coil is a major factor affecting NMR resolution and also the sensitivity of the measurement. So far, this fact is only considered when small sample amounts are used, where care should be taken to place the sample in the …
Catecholamine Response Curves of Male Hypertensives Identified by Lehmacher's Two Sample Configural Frequency Analysis
1997
A new application of LEHMACHER'S (1980) marginal homogeneity sign tests is given by analysis of bivariate response curves (or response surfaces) in two unpaired samples of hypertensive versus normotensive patients. Rationale and computations are illustrated by empirical data from sympathomedullary stress research.
The dynamics of personal norms and the determinants of cultural homogeneity
2017
This article studies the emergence of cultural homogeneity in personal norms when the behavior of heterogeneous individuals is driven both by economic incentives and by personal norms. Agents participate in a team production game by choosing their level of costly effort. Norms evolve along the life cycle of the individuals according to two psychological forces: cognitive dissonance or consistency and informational conformity. The model sheds light on how primitive economic and behavioral parameters such as the distribution of skills, the income distribution, and the levels of materialism, conformism, and consistency in the group determine the long-run culture and its degree of cultural homo…