bluuebunny/crossref_metadata_2025_split huggingface dataset:
How stress selects for reversible phenotypic plasticity
Authors: GABRIEL W. 
Published: March 2006

AbstractStress occurring in periods shorter than life span strongly selects for reversible phenotypic plasticity, for maximum reliability of stress indicating cues and for minimal response delays. The selective advantage of genotypes that are able to produce adaptive reversible plastic phenotypes is calculated by using the concept of environmental tolerance. Analytic expressions are given for optimal values of mode and breadth of tolerance functions for stress induced and non‐induced phenotypes depending on (1) length of stress periods, (2) response delay for switching into the induced phenotype, (3) response delay for rebuilding the non‐induced phenotype, (4) intensity of stress, i.e. mean value of the stress inducing environment, (5) coefficient of variation of the stress environment and (6) completeness of information available to the stressed organism. Adaptively reversible phenotypic plastic traits will most probably affect fitness in a way that can be described by simultaneous reversible plasticity in mode and breadth of tolerance functions.
Microsatellites for ecologists: a practical guide to using and evaluating microsatellite markers
Authors: Selkoe Kimberly A. , Toonen Robert J. 
Published: March 2006

AbstractRecent improvements in genetic analysis and genotyping methods have resulted in a rapid expansion of the power of molecular markers to address ecological questions. Microsatellites have emerged as the most popular and versatile marker type for ecological applications. The rise of commercial services that can isolate microsatellites for new study species and genotype samples at reasonable prices presents ecologists with the unprecedented ability to employ genetic approaches without heavy investment in specialized equipment. Nevertheless, the lack of accessible, synthesized information on the practicalities and pitfalls of using genetic tools impedes ecologists’ ability to make informed decisions on using molecular approaches and creates the risk that some will use microsatellites without understanding the steps needed to evaluate the quality of a genetic data set. The first goal of this synthesis is to provide an overview of the strengths and limitations of microsatellite markers and the risks, cost and time requirements of isolating and using microsatellites with the aid of commercial services. The second goal is to encourage the use and consistent reporting of thorough marker screening to ensure high quality data. To that end, we present a multistep screening process to evaluate candidate loci for inclusion in a genetic study that is broadly targeted to both novice and experienced geneticists alike.
The Implementation of Corporate Governance Principles in an Emerging Economy: a critique of the situation in Cyprus
Authors: Krambia‐Kapardis Maria , Psaros Jim 
Published: March 2006

When the Cyprus economy was booming in the 1990s, key issues emanating from sound corporate governance, such as accountability, transparency and effective independent boards were not deemed important. However, largely as a result of the Cyprus stock exchange collapse of 2000, this view changed. In September 2002, due to the collapse, the Cyprus Stock Exchange implemented a Corporate Governance Code predicated largely on Anglo‐Saxon principles of corporate governance.This paper reports the result of a study into levels of compliance with the Code by companies listed on the Cyprus Stock Exchange. The findings indicate that only a small minority complied with all significant aspects of the Code, and the vast majority did not comply with any. While the Code was well intended, the intended reforms do not appear to have significantly improved corporate governance. This is perhaps not surprising, given that the Cyprus equity markets and corresponding legislative support pertaining to corporate governance are in their infancy. In addition, some typical free market controls (e.g. low degree of concentration of ownership, reliable and timely information flows and opportunities for investor diversification) that facilitate international institutional investment do not exist in Cyprus. This suggests that the introduction of a Corporate Governance Code in Cyprus, or other developing economies, is likely to have only minimal impact unless it is supported by other initiatives. However, recent developments in Cyprus relating to greater education as to the benefits of corporate governance, as well as more stringent listing rules for companies lacking aspects of corporate governance, suggest that Cyprus is making serious endeavours to improve the corporate governance of its listed companies.
Wavelet-based Functional Mixed Models
Authors: Morris Jeffrey S. , Carroll Raymond J. 
Published: March 2006

SummaryIncreasingly, scientific studies yield functional data, in which the ideal units of observation are curves and the observed data consist of sets of curves that are sampled on a fine grid. We present new methodology that generalizes the linear mixed model to the functional mixed model framework, with model fitting done by using a Bayesian wavelet-based approach. This method is flexible, allowing functions of arbitrary form and the full range of fixed effects structures and between-curve covariance structures that are available in the mixed model framework. It yields nonparametric estimates of the fixed and random-effects functions as well as the various between-curve and within-curve covariance matrices. The functional fixed effects are adaptively regularized as a result of the non-linear shrinkage prior that is imposed on the fixed effects’ wavelet coefficients, and the random-effect functions experience a form of adaptive regularization because of the separately estimated variance components for each wavelet coefficient. Because we have posterior samples for all model quantities, we can perform pointwise or joint Bayesian inference or prediction on the quantities of the model. The adaptiveness of the method makes it especially appropriate for modelling irregular functional data that are characterized by numerous local features like peaks.
Nonparametric Methods for Solving the Berkson Errors-in-Variables Problem
Authors: Delaigle Aurore , Hall Peter , Qiu Peihua 
Published: March 2006

SummaryIt is common, in errors-in-variables problems in regression, to assume that the errors are incurred ‘after the experiment’, in that the observed value of the explanatory variable is an independent perturbation of its true value. However, if the errors are incurred ‘before the experiment’ then the true value of the explanatory variable equals a perturbation of its observed value. This is the context of the Berkson model, which is increasingly attracting attention in parametric and semiparametric settings. We introduce and discuss nonparametric techniques for analysing data that are generated by the Berkson model. Our approach permits both random and regularly spaced values of the target doses. In the absence of data on dosage error it is necessary to propose a distribution for the latter, but we show numerically that our method is robust against that assumption. The case of dosage error data is also discussed. A practical method for smoothing parameter choice is suggested. Our techniques for errors-in-variables regression are shown to achieve theoretically optimal convergence rates.
Generalized Linear Array Models with Applications to Multidimensional Smoothing
Authors: Currie I. D. , Durban M. , Eilers P. H. C. 
Published: March 2006

SummaryData with an array structure are common in statistics, and the design or regression matrix for analysis of such data can often be written as a Kronecker product. Factorial designs, contingency tables and smoothing of data on multidimensional grids are three such general classes of data and models. In such a setting, we develop an arithmetic of arrays which allows us to define the expectation of the data array as a sequence of nested matrix operations on a coefficient array. We show how this arithmetic leads to low storage, high speed computation in the scoring algorithm of the generalized linear model. We refer to a generalized linear array model and apply the methodology to the smoothing of multidimensional arrays. We illustrate our procedure with the analysis of three data sets: mortality data indexed by age at death and year of death, spatially varying microarray background data and disease incidence data indexed by age at death, year of death and month of death.
Variance Stabilization for a Scalar Parameter
Authors: DiCiccio Thomas J. , Monti Anna Clara , Alastair Young G. 
Published: March 2006

SummaryWe present a variance stabilizing transformation for inference about a scalar parameter that is estimated by a function of a multivariate M-estimator. The transformation proposed is automatic, computationally simple and can be applied quite generally. Though it is based on an intuitive notion and entirely empirical, the transformation is shown to have an appropriate justification in providing variance stabilization when viewed from both parametric and nonparametric perspectives. Further, the transformation repairs deficiencies of existing methods for variance stabilization. The transformation proposed is illustrated in a range of examples, and its effectiveness to yield confidence limits having low coverage error is demonstrated in a numerical example.
Functional Clustering by Bayesian Wavelet Methods
Authors: Ray Shubhankar , Mallick Bani 
Published: March 2006

SummaryWe propose a nonparametric Bayes wavelet model for clustering of functional data. The wavelet-based methodology is aimed at the resolution of generic global and local features during clustering and is suitable for clustering high dimensional data. Based on the Dirichlet process, the nonparametric Bayes model extends the scope of traditional Bayes wavelet methods to functional clustering and allows the elicitation of prior belief about the regularity of the functions and the number of clusters by suitably mixing the Dirichlet processes. Posterior inference is carried out by Gibbs sampling with conjugate priors, which makes the computation straightforward. We use simulated as well as real data sets to illustrate the suitability of the approach over other alternatives.
Incorporating Serotypes into Family Based Association Studies Using the MFG Test
Authors: Minassian S. L. , Palmer C. G. S. , Turunen J. A. , Paunio T. , Lönnqvist J. , Peltonen L. , Woodward J. A. , Sinsheimer J. S. 
Published: March 2006

SummaryFamily based association tests are widely used to detect genetic effects. The focus of this paper is the maternal‐fetal genotype (MFG) incompatibility test, a family based association test which can be used to detect genetic effects that contribute to disease, including alleles in the child that increase disease risk, maternal alleles that increase disease risk in the child, and maternal‐fetal genotype incompatibilities. Consideration of incomplete data resulting from using serotypes could expand the power of the MFG test for detecting genetic effects. Serotypes may be all that are available in certain families, or preferred because of convenience or low cost, and thus a modification of the MFG test will allow optimal use of such data. The modified MFG likelihood can accommodate the incomplete data that result from using serotypes rather than the corresponding codominant genotypes. The modified MFG test was evaluated with serotypes and genotypes from families with members affected with schizophrenia. In addition, simulation studies were performed. Results of the data analyses and simulation studies showed that serotypes can be used to augment genotypes within a sample, to increase power to detect effects when the candidate gene produces serotypes.
Forage selection by mule deer: does niche breadth increase with population density?
Authors: Nicholson M. C. , Bowyer R. T. , Kie J. G. 
Published: March 2006

AbstractEffects of population density of mule deer Odocoileus hemionus on forage selection were investigated by comparing diet characteristics of two subpopulations of deer in southern California, USA, that differed in population density during winter. Quality of diet for deer, as indexed by faecal crude protein, was higher at the low‐density site than at the high‐density site in winter, when deer densities were different. Quality of diet was similar in summer when both areas had comparable densities of deer. Both outcomes are consistent with predictions from density‐dependent selection of diets by deer. Dietary niche breadth, however, differed in a manner opposite to predictions of niche theory based on diet selection under an ideal‐free distribution. During winter, when differences in density between the two study sites were pronounced, niche breadth along the dietary axis in the low‐density area was twice that of the high‐density site. Generalist herbivores feeding primarily on low‐quality browse at high population density in winter would be expected to increase their dietary breadth by feeding on additional species of plants as they depleted their food supply. Mule deer in our study, however, decreased the breadth of their dietary niche as population density increased. We hypothesize that by rapidly eliminating high‐quality forages from an area by heavy grazing, deer at higher population densities narrowed their dietary niche. Theoretical models for changes in niche dimensions, including the ideal‐free distribution, need to consider such empirical outcomes.
Efficiency of strip‐ and line‐transect surveys of African savanna mammals
Authors: Ogutu J. O. , Bhola N. , Piepho H.‐P. , Reid R. 
Published: March 2006

AbstractEffective management and conservation of wildlife populations require reliable estimates of population size, which can be difficult and costly to obtain. We evaluated how precision in estimates of herd size and abundance varies with sample size and strip width using two field surveys and bootstrap resampling of the field data. We also examined precision under distance sampling and evaluated the cost‐effectiveness of both survey techniques. Precision in estimates of abundance increased with increasing sample size and varied with strip width independently of sample size. The hazard rate key function was best for five species in two surveys with contrasting visibility conditions. Precision in density was more sensitive to the number of herds sighted than to variation in herd size and effective strip width for distance sampling. Strip counts produced lower abundance estimates but higher precision than distance sampling. We estimated that distance sampling would cost about US$3.1 km−1of transect. Strip counts deserve serious consideration for surveys of species that occur at high densities and form large, loose agglomerations but distance methods are suitable for species occurring at moderate to low densities in areas where visibility varies substantially. Distance sampling may thus need to be supplemented by strip counts to efficiently estimate densities of rare, abundant and highly clustered multi‐species assemblages of African savanna mammals. In small areas, it may often prove necessary to conduct several surveys to obtain adequate sample sizes for distance models.
Age‐specific resource investment strategies: evidence from female Richardson's ground squirrels (Spermophilus richardsonii)
Authors: Broussard D. R. , Michener G. R. , Dobson F. S. 
Published: March 2006

AbstractTo avoid a possible cost to their future survival and/or reproduction, individuals must balance their somatic and reproductive investments. The van Noordwijk and De Jong model of resource investment predicts that investments into reproduction and soma can vary among individuals of a population based on the variation in the total amount of energy that individuals acquire. With principal components analysis (PCA), we created two axes of life history for female Richardson's ground squirrels Spermophilus richardsonii: an index of total energy investment (PC1) and an index of investment tactic (PC2). Using these indices, we examined patterns of resource allocation to reproductive and somatic investments. Because yearling female Richardson's ground squirrels complete growth to adult size during pregnancy and early lactation, their somatic needs exceed those of older, fully grown females. Therefore, we predicted that yearlings would show more evidence of a tradeoff between reproductive and somatic investments compared with older females. Both yearling and older females invested four to five times more mass into their litters than into their own body mass. With increasing total investment, yearling females increased investment in both reproduction and themselves, whereas older females invested relatively more in reproduction than themselves. Regardless of age, females that emerged heavier from hibernation invested fewer resources into themselves and more into their litters. Variation in total energy investment and investment tactic indices was similar for yearling and older females. Contrary to our prediction, however, yearling females showed positive associations between reproductive and somatic investments, whereas older females exhibited showed no significant association between reproductive and somatic investments.
Photoreceptive organs in larvae of Spionidae (Annelida) and Sipuncula
Authors: Radashevsky V. I. , Migotto A. E. 
Published: March 2006

AbstractA pair of spherical unpigmented ocelli in addition to pigmented eyes have been observed in the anterior part of the prostomium in larvae of more than 40 species of Spionidae examined alive with light microscopy. Ocelli become visible in larvae at the one‐ to three‐segment stage, increase in size as growth proceeds, and probably disintegrate in the course of metamorphosis because they were not observed in adults and settled juveniles. One pair of transparent, spherical bodies is also found in the anterior part of the head of planktotrophic pelagosphera larvae of Sipuncula. These bodies are in a similar position and have a similar appearance and size to unpigmented ocelli in Spionidae larvae. A pair of epidermal invaginations, densely covered with short cilia, is also observed antero‐laterally in the head in pelagospheras of one species. These invaginations appear similar to the nuchal organs present in many polychaete larvae. Photoreceptive organs so far reported for sipunculan larvae comprise only pigmented eyes. Unpigmented ocelli and nuchal organs have never been reported in pelagospheras. Further ultrastructural investigations on sipunculan larvae are encouraged to clarify the composition, function and morphogenesis of transparent, spherical bodies and ciliated invaginations in the anterior part of the head. Such investigations may help to better understand the nature of photoreceptive structures and nuchal organs in Sipuncula, and also contribute to phylogenetic hypotheses regarding relationships of the Sipuncula and Annelida.
Inter‐ and intracellular interactions of Nogo: new findings and hypothesis
Authors: Teng Felicia Y. H. , Ling Belinda M. T. , Tang Bor Luen 
Published: March 2006

AbstractThe molecule Nogo has captured the imagination of many as a possible key player, and therefore therapeutic target, in the pathological settings of central nervous system (CNS) injury and degenerative pathology. Found in both glial cells and neurons, the endogenous, physiological role of Nogo is as yet unknown. Recently reported targeted disruption of the Nogo gene did not result in any obvious neuro‐anatomical or neurological phenotype. Compared with wild‐type mice, Nogo‐deficient mice also did not exhibit a truly convincing enhancement in their ability to regenerate CNS neurons upon injury. Does the molecule have any important physiological function at all? Other recent discoveries of new interacting partners of Nogo at the mitochondria and the CNS paranode suggest intriguing links to the modulation of apoptosis and developmental organization or signalling at the axoglial junction.
GABAB receptors in 5‐HT transporter‐ and 5‐HT1A receptor‐knock‐out mice: further evidence of a transduction pathway shared with 5‐HT1A receptors
Authors: La Cour Clotilde Mannoury , Hanoun Naïma , Melfort Maxette , Hen René , Lesch Klaus‐Peter , Hamon Michel , Lanfumey Laurence 
Published: March 2006

AbstractThe functional properties of GABAB receptors were examined in the dorsal raphe nucleus (DRN) and the hippocampus of knock‐out mice devoid of the 5‐HT transporter (5‐HTT–/–) or the 5‐HT1A receptor (5‐HT1A–/–). Electrophysiological recordings in brain slices showed that the GABAB receptor agonist baclofen caused a lower hyperpolarization and neuronal firing inhibition of DRN 5‐HT cells in 5‐HTT–/– versus 5‐HTT+/+ mice. In addition, [35S]GTP‐γ‐S binding induced by GABAB receptor stimulation in the DRN was approximately 40% less in these mutants compared with wild‐type mice. In contrast, GABAB receptors appeared functionally intact in the hippocampus of 5‐HTT–/–, and in both this area and the DRN of 5‐HT1A‐knock‐out mice. The unique functional changes of DRN GABAB receptors closely resembled those of 5‐HT1A autoreceptors in 5‐HTT–/– mice, further supporting the idea that both receptor types are coupled to a common pool of G‐proteins in serotoninergic neurons.
Caspase‐mediated proteolysis of the polyglutamine disease protein ataxin‐3
Authors: Berke Sarah J Shoesmith , Schmied Francisca A Flores , Brunt Ewout R. , Ellerby Lisa M. , Paulson Henry L. 
Published: March 2006

AbstractSpinocerebellar ataxia type‐3, also known as Machado‐Joseph Disease, is one of many inherited neurodegenerative disorders caused by polyglutamine‐encoding CAG repeat expansions in otherwise unrelated disease genes. Polyglutamine disorders are characterized by disease protein misfolding and aggregation; often within the nuclei of affected neurons. Although the precise mechanism of polyglutamine‐mediated cell death remains elusive, evidence suggests that proteolysis of polyglutamine disease proteins by caspases contributes to pathogenesis. Using cellular models we now show that the endogenous spinocerebellar ataxia type‐3 disease protein, ataxin‐3, is proteolyzed in apoptotic paradigms, resulting in the loss of full‐length ataxin‐3 and the corresponding appearance of an approximately 28‐kDa fragment containing the glutamine repeat. Broad‐spectrum caspase inhibitors block ataxin‐3 proteolysis and studies suggest that caspase‐1 is a primary mediator of cleavage. Site‐directed mutagenesis experiments eliminating three, six or nine potential caspase cleavage sites in the protein suggest redundancy in the site(s) at which cleavage can occur, as previously described for other disease proteins; but also map a major cleavage event to a cluster of aspartate residues within the ubiquitin‐binding domain of ataxin‐3 near the polyglutamine tract. Finally, caspase‐mediated cleavage of expanded ataxin‐3 resulted in increased ataxin‐3 aggregation, suggesting a potential role for caspase‐mediated proteolysis in spinocerebellar ataxia type‐3 pathogenesis.