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Experiments Addressing (experiment + addressing)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

A simulation study comparing different experimental designs for estimating uptake and elimination rates

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006
Bryan R. Bell
Abstract The design of ecotoxicological studies requires decisions about the number and spacing of exposure groups tested, the number of replications, the spacing of sampling times, the duration of the study, and other considerations. For example, geometric spacing of sampling times or toxicant concentrations is often used as a default design. Optimal design methods in statistics can suggest alternative spacing of sampling times that yield more precise estimates of regression coefficients. In this study, we use a computer simulation to explore the impact of the spacing of sampling times and other factors on the estimation of uptake and elimination rate constants in an experiment addressing the bioaccumulation of a contaminant. Careful selection of sampling times can result in smaller standard errors for the parameter estimates, thereby allowing the construction of smaller, more precise confidence intervals. Thus, the effort invested in constructing an optimal experimental design may result in more precise inference or in a reduction of replications in an experimental design. [source]

Selective exposure to information: the impact of information limits

EUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 4 2005
Peter Fischer
In research on selective exposure to information, people have been found to predominantly seek information supporting rather than conflicting with their opinion. In most of these studies, participants were allowed to search for as many pieces of information as they liked. However, in many situations, the amount of information that people can search for is restricted. We report four experiments addressing this issue. Experiment 1 suggests that objective limits regarding the maximum number of pieces of information the participants could search for increases the preference for selecting supporting over conflicting information. In Experiment 2, just giving participants a cue about information scarcity induces the same effect, even in the absence of any objective restrictions. Finally, Experiment 3 and 4 clarify the underlying psychological process by showing that information limits increase selective exposure to information because information search is guided by the expected information quality, which is basically biased towards supporting information, and information limits act to reinforce this tendency. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The aging of early B-cell precursors

IMMUNOLOGICAL REVIEWS, Issue 1 2005
David Allman
Summary:, B-cell genesis in the bone marrow declines with advancing age. In this review, we discuss our current understanding of why B-cell production rates decline with age with a special emphasis on why age-related factors might target very early lymphoid precursors. We consider the impact of aging on cytokine responsiveness and how current models for lineage relationships for very early B- and T-cell precursors might influence interpretations of experiments addressing age-associated declines in B- and T-cell differentiation. This discussion centers on the notion that aging affects events associated with the process by which hematopoietic stem cells are guided toward the B-cell pathway. Finally, we present a model in which the age-associated loss of early B-cell precursors is linked to suboptimal function of key transcriptional regulators of very early B-cell development. [source]

Transcriptional and translational control of C/EBPs: The case for "deep" genetics to understand physiological function

BIOESSAYS, Issue 8 2010
Claus Nerlov
Abstract The complexity of organisms is not simply determined by the number of their genes, but to a large extent by how gene expression is controlled. In addition to transcriptional regulation, this involves several layers of post-transcriptional control, such as translational repression, microRNA-mediated mRNA degradation and translational inhibition, alternative splicing, and the regulated generation of functionally distinct gene products from a single mRNA through alternative use of translation initiation sites. Much progress has been made in describing the molecular basis for these gene regulatory mechanisms. However, it is now a major challenge to translate this knowledge into deeper understanding of the physiological processes, both normal and pathological, that they govern. Using the C/EBP family of transcription factors as an example, the present review describes recent genetic experiments addressing this general problem and discusses how the physiological importance of newly discovered regulatory mechanisms might be determined. [source]