نتایج جستجو برای: heterogeneity

تعداد نتایج: 95065  

Journal: :BioEssays : news and reviews in molecular, cellular and developmental biology 2011
Imke G de Jong Patsy Haccou Oscar P Kuipers

Bacteria have developed an impressive ability to survive and propagate in highly diverse and changing environments by evolving phenotypic heterogeneity. Phenotypic heterogeneity ensures that a subpopulation is well prepared for environmental changes. The expression bet hedging is commonly (but often incorrectly) used by molecular biologists to describe any observed phenotypic heterogeneity. In ...

Journal: :Journal of theoretical biology 2006
Priyanga Amarasekare

A great deal is known about the influence of dispersal on species that interact via competition or predation, but very little is known about the influence of dispersal on species that interact via both competition and predation. Here, I investigate the influence of dispersal on the coexistence and abundance-productivity relationships of species that engage in intraguild predation (IGP: competin...

Journal: :Lifetime data analysis 2017
Andreas Groll Gerhard Tutz

Several variable selection procedures are available for continuous time-to-event data. However, if time is measured in a discrete way and therefore many ties occur models for continuous time are inadequate. We propose penalized likelihood methods that perform efficient variable selection in discrete survival modeling with explicit modeling of the heterogeneity in the population. The method is b...

Journal: :Fly 2009
Annalise B Paaby Paul S Schmidt

Drosophila melanogaster has been an historically important system for investigating the genetic basis of longevity, and will continue to be valuable as new technologies permit genomic explorations into the biology of aging. The utility of D. melanogaster resides in two resources: its powerful genetic tools as a model system, and a natural ecology that provides substantial genetic variation acro...

Journal: :Psychological methods 2008
Douglas G Bonett

The currently available meta-analytic methods for correlations have restrictive assumptions. The fixed-effects methods assume equal population correlations and exhibit poor performance under correlation heterogeneity. The random-effects methods do not assume correlation homogeneity but are based on an equally unrealistic assumption that the selected studies are a random sample from a well-defin...

Journal: :Lancet 2003
Helen M Colhoun Paul M McKeigue George Davey Smith

Inability to replicate many results has led to increasing scepticism about the value of simple association study designs for detection of genetic variants contributing to common complex traits. Much attention has been drawn to the problems that might, in theory, bedevil this approach, including confounding from population structure, misclassification of outcome, and allelic heterogeneity. Other...

Journal: :Journal of theoretical biology 2004
Jonathan B Shurin Priyanga Amarasekare Jonathan M Chase Robert D Holt Martha F Hoopes Mathew A Leibold

Many models of local species interactions predict the occurrence of priority effects due to alternative stable equilibria (ASE). However, few empirical examples of ASE have been shown. One possible explanation for the disparity is that local ASE are difficult to maintain regionally in patch dynamic models. Here we examine two possible mechanisms for regional coexistence of species engaged in lo...

2004
ORLANDO C. RICHARD SEAN DWYER KEN CHADWICK

Extending previous theorizing on cultural diversity’s organizational effects by integrating value-in-diversity and social identity perspectives with the framework of Blau’s (1977) theory of heterogeneity, we hypothesized curvilinear relationships between racial and gender diversity in management and firm performance. We evaluated relationships within the context of firm-level entrepreneurial or...

1996
Ounissa Larab Aïcha-Nabila Benharkat

The success of schema integration in multidatabase systems relies heavily on the determination of complete and refined correspondence relationships between them. So, the candidate schemas to be integrated must be rich and precise semantically, i.e., each of their data elements must be sufficiently defined for to be distinguished from others or identified to some of them. Our schema integration ...

Journal: :iranian journal of oil & gas science and technology 2014
maryam ghorbani mohammad reza khorsand mohsen masihi

the performance of water flooding can be investigated by using either detail numerical modeling or simulation, or simply through the analytical buckley-leverett (bl) model. the buckley-leverett analytical technique can be applied to one-dimensional homogeneous systems. in this paper, the impact of heterogeneity on water flooding performance and fractional flow curve is investigated. first, a ba...

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