Search results for "selection"
showing 10 items of 1940 documents
Empirical study of the dependence of the results of multivariable flexible survival analyses on model selection strategy
2008
Flexible survival models, which avoid assumptions about hazards proportionality (PH) or linearity of continuous covariates effects, bring the issues of model selection to a new level of complexity. Each ‘candidate covariate’ requires inter-dependent decisions regarding (i) its inclusion in the model, and representation of its effects on the log hazard as (ii) either constant over time or time-dependent (TD) and, for continuous covariates, (iii) either loglinear or non-loglinear (NL). Moreover, ‘optimal’ decisions for one covariate depend on the decisions regarding others. Thus, some efficient model-building strategy is necessary. We carried out an empirical study of the impact of the model …
INTERSPECIFIC AGGRESSION CAUSES NEGATIVE SELECTION ON SEXUAL CHARACTERS
2005
Interspecific aggression originating from mistaken species recognition may cause selection on secondary sexual characters, but this hypothesis has remained untested. Here we report a field experiment designed to test directly whether interspecific aggression causes selection on secondary sexual characters, wing spots, in wild damselfly populations. Males of Calopteryx virgo are more aggressive toward males of C. splendens with large than with small wing spots. This differential interspecific aggression may cause negative selection on wing spot size. Indeed, our results show that directional survival selection on wing spot size of C. splendens males was changed by experimental removal of C. …
Social behavior, chemical communication, and adult neurogenesis: Studies of scent mark function in Podarcis wall lizards
2011
Lacertid lizards have been hailed as a model system for the study of reptilian chemical communication. However, results obtained with the genus Podarcis, a diverse group of wall lizards with complex systematics, challenge emerging paradigms and caution against hasty generalizations. Here we review the available evidence on the role of chemical stimuli in male-female and male-male interactions in Iberian Podarcis. Males of several species can discriminate between chemicals left on substrates by females of their own or a different species, suggesting that differences in female chemical cues may underlie species recognition in this group. Females, on the other hand, do not respond differential…
Simultaneous age‐dependent and age‐independent sexual selection in the lekking black grouse(Lyrurus tetrix)
2014
Individuals' reproductive success is often strongly associated with their age, with typical patterns of early‐life reproductive improvement and late‐life senescence. These age‐related patterns are due to the inherent trade‐offs between life‐history traits competing for a limited amount of resources available to the organisms. In males, such trade‐offs are exacerbated by the resource requirements associated with the expression of costly sexual traits, leading to dynamic changes in trait expression throughout their life span. Due to the age dependency of male phenotypes, the relationship between the expression of male traits and mating success can also vary with male age. Hence, using longitu…
Do randomized clinical trial selection criteria reflect levels of risk as observed in a general population of acute myocardial infarction survivors? …
2016
IF 4.638; International audience; Background: Few clinical trials have focused on populations with a history of distant myocardial infarction (MI). The PEGASUS trial assessed the impact of dual antiplatelet therapy in such patients, selected by enrichment criteria of high cardiovascular risk. Whether the PEGASUS population reflects the risk of a broader post-MI population is questionable. We analyzed whether 4-year mortality of a routine-practice population would differ according to the inclusion and exclusion criteria used in PEGASUS.Methods: FAST-MI is a nationwide French registry recruiting acute MI patients in November 2005; 2490 patients alive and without recurrent MI at one year were …
Temporal stability and representational distinctiveness: Key functions of orthographic working memory
2011
A primary goal of working memory research has been to understand the mechanisms that permit working memory systems to effectively maintain the identity and order of the elements held in memory for sufficient time as to allow for their selection and transfer to subsequent processing stages. Based on the performance of two individuals with acquired dysgraphia affecting orthographic working memory (WM; the graphemic buffer), we present evidence of two distinct and dissociable functions of orthographic WM. One function is responsible for maintaining the temporal stability of letters held in orthographic WM, while the other is responsible for maintaining their representational distinctiveness. T…
Mid-term Results of Chimney and Periscope Grafts in Supra-aortic Branches in High Risk Patients
2017
Purpose Report mid-term outcomes of thoracic endovascular aneurysm repair (TEVAR) with chimney and periscope grafts (CPG) in supra-aortic branches (SAB). Methods Retrospective analysis, from October 2009 to May 2014, of patients with aneurysms requiring TEVAR with zone 0/1/2 proximal landing in association with at least one CPG in the SAB. All patients were considered at high risk for conventional surgery. Peri-operative mortality and morbidity, retrograde type A dissection, maximum aortic transverse diameter (TD) and its post-operative evolution, endoleak, survival, freedom from cardiovascular re-interventions, and CPG freedom from occlusion during the follow-up were analysed. Results Fort…
Adaptive significance of synchronous chorusing in an acoustically signalling wolf spider
2004
Synchronous sexual signalling is a behavioural phenomenon that has received considerable theoretical interest, but surprisingly few empirical tests have been conducted. Here, we present a set of experiments designed to determine (i) whether the sexual signalling of the drumming wolf spider Hygrolycosa rubrofasciata is synchronous, and (ii) whether the synchrony may have evolved through female preference. Using controlled playback experiments, we found that males actively synchronized their drumming bouts with other males and females significantly preferred closely synchronized drumming clusters compared with loose clusters. In loose clusters, the first drumming signals attracted the most fe…
Ramucirumab versus placebo as second-line treatment in patients with advanced hepatocellular carcinoma following first-line therapy with sorafenib (R…
2015
Background: VEGF and VEGF receptor-2-mediated angiogenesis contribute to hepatocellular carcinoma pathogenesis. Ramucirumab is a recombinant IgG1 monoclonal antibody and VEGF receptor-2 antagonist. We aimed to assess the safety and efficacy of ramucirumab in advanced hepatocellular carcinoma following first-line therapy with sorafenib. Methods: In this randomised, placebo-controlled, double-blind, multicentre, phase 3 trial (REACH), patients were enrolled from 154 centres in 27 countries. Eligible patients were aged 18 years or older, had hepatocellular carcinoma with Barcelona Clinic Liver Cancer stage C disease or stage B disease that was refractory or not amenable to locoregional therapy…
Hyperalgesia and opioid switching
2005
Opioids, intended to abolish pain, can unexpectedly produce hyperalgesia, particularly during rapid opioid escalation. Opioid switching could be a therapeutic option in a condition of opioid-induced tolerance or hyperalgesia, but conversion ratios between opioids are difficult to apply in this context and require strict surveillance and expertise. This situation is challenging, because the rapid escalation of opioid doses, possibly due to the development of opioid-induced tolerance, can cause hyperalgesia. To avoid this adverse effect, clinicians need to refine their assessment of pain treatment and consider opioid switching. The authors present a case report in which switching from fentan…