Search results for "Likelihood Functions"
showing 10 items of 101 documents
The early motor milestones in infancy and later motor skills in toddlers: a structural equation model of motor development.
2006
The relationship between the achievement of early motor milestones in infancy and later motor development was studied in 130 children with (N = 66, 35 male/31 female) and without (N = 64, 31 male/35 female) familial risk for dyslexia. A structured parental questionnaire was used to assess motor development in infancy, and the Movement Assessment Battery for Children was used to assess motor skills at age 3.5 years. No differences were found at the group level and therefore the structural equation model was constructed by entering both groups simultaneously. An Early Body Control factor, computed from the infant data, explained 38% of the variance of the Gross Motor Skills factor at the age …
Evolution of alternative male morphotypes in oxyurid nematodes: a case of convergence?
2014
Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sis…
Exploring the potential of life-history key innovation: brook breeding in the radiation of the Malagasy treefrog genus Boophis
2002
The treefrog genus Boophis is one of the most species-rich endemic amphibian groups of Madagascar. It consists of species specialized to breeding in brooks (48 species) and ponds (10 species). We reconstructed the phylogeny of Boophis using 16S ribosomal DNA sequences (558 bp) from 27 species. Brook-breeders were monophyletic and probably derived from an ancestral pond-breeding lineage. Pond-breeders were paraphyletic. The disparity in diversification among pond-breeders and brook-breeders was notable among endemic Malagasy frogs, although it was not significant when considering Boophis alone. Sibling species which have different advertisement calls but are virtually indistinguishable by mo…
Sexual size dimorphism predicts rates of sequence evolution of SPerm Adhesion Molecule 1 (SPAM1, also PH-20) in monkeys, but not in hominoids (apes i…
2010
Based on a dataset comprising coding DNA sequences of 23 anthropoid primates, we herein investigate if rates of sequence evolution of SPerm Adhesion Molecule 1 (SPAM1, also PH-20), which participates in sperm–egg interaction, is lower in more sexually dimorphic species. For comparison, we analyze sequence evolution of apolipoprotein A-IV (APOA4) and apolipoprotein A-V (APOA5), which should evolve under less or even no sexual selection given their expression in blood, digestive tract, liver, and lungs. Regression analyses provides significant support for a negative dependence of SPAM1 derived branch-specific ratios of non-synonymous to synonymous substitution rates (dN/dS) on sexual size dim…
Testing direct and indirect effects of sports participation on perceived health in Spanish adolescents between 15 and 18 years of age.
2003
This paper examines the direct and indirect effects of sports participation on perceived health. It is based on a representative sample of middle adolescents aged 15-18 (N=1038, M age=16.31, S.D.=0.92; 510 boys and 528 girls) from the Valencian Community (Spain). This study used two different models; Model A is an adaptation of Thorlindsson, Vilhjalmsson and Valgeirsson's (Social Science and Medicine 31 (1990) 551) model which introduces smoking, alcohol use, feelings of anxiety, feelings of depression and psychophysiological symptoms as mediator variables; Model B is an extension of Model A with perceived physical fitness as an added mediator variable. Both models show a good fit to the da…
A flexible approach to the crossing hazards problem
2010
We propose a simple and flexible framework for the crossing hazards problem. The method is not confined to two-sample problems, but may also work with continuous exposure variables whose effect changes its sign at some time-point of the observed follow-up time. Penalized partial likelihood estimation relies upon the assumption of a smooth hazard ratio via low-rank basis splines with a conventional difference penalty to ensure smoothness, and additional ad hoc penalties to obtain restricted estimates useful in the context of crossing hazards. The framework naturally also leads to a statistical test that has good power for revealing a global effect under several alternatives, including crossi…
Intraoral electrostimulator for xerostomia relief: a long-term, multicenter, open-label, uncontrolled, clinical trial
2012
Objective A previous sham-controlled multinational study demonstrated the short-term efficacy and safety for xerostomia treatment of an intraoral device that delivers electrostimulation to the lingual nerve. The objective of this study was to test the hypothesis that those beneficial effects would be sustained over an 11-month period. Study Design The device was tested on a mixed sample of 94 patients with xerostomia in an open-label, uncontrolled, prospective multicenter trial. Statutory outcome assessments were done at 5th, 8th, and 11th months and analyzed by multiple comparisons. Results Improvements achieved at month 5 from baseline were sustained throughout the follow-up period for th…
Use of xylitol chewing gum among Finnish schoolchildren
2000
The preventive, and partly the remineralizing, effect of xylitol was shown in Finland in the Turku Sugar Studies in 1971-73. Since then, several clinical trials in many countries have confirmed these results. In Finland, oral health personnel have recommended daily use of xylitol chewing gum in their dental health education. Moreover, commercial companies have advertised xylitol, emphasizing in particular its caries preventive effects. All Nordic dental associations have given their recommendations for xylitol use. The aim of this study was to describe how this health habit has been adopted by Finnish schoolchildren. The study was part of the comprehensive cross-national survey on Health Be…
Results from an international case-control study of childhood brain tumors: The role of prenatal vitamin supplementation
1998
An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976 to 1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1051 cases and 1919 controls from eight geographic areas in North America, Europe, and Israel. Although risk estimates varied by study center, combined results suggest that maternal supplementation for two trimesters may decrease risk of brain tumor (odds ratio [OR] 0.7, 95% confidence interval [CI] 0.5-0.9), with a trend of less risk with longer duration of use (p trend = 0.0007). The greatest risk reduction was among children diagnosed under 5 years of …
Low Levels of Mitochondrial DNA and Symbiont Diversity in the Worldwide Agricultural Pest, the Greenhouse Whitefly Trialeurodes vaporariorum (Hemipte…
2015
Trialeurodes vaporariorum, the greenhouse whitefly, is a cosmopolitan agricultural pest. Little is known about the genetic diversity of T. vaporariorum and the bacterial symbionts associated with this species. Here, we undertook a large phylogeographic study by investigating both the mitochondrial (mt) diversity and the infection status of 38 T. vaporariorum collections from 18 countries around the world. Genetic diversity of T. vaporariorum was studied by analyzing sequence data from the mt cytochrome oxidase I, cytochrome b, and NADH dehydrogenase subunit 5 genes. Maximum-likelihood (ML) phylogeny reconstruction delineated 2 clades characterized by limited sequence divergence: one clade c…