Quantum transport and integrability of the Anderson model for a quantum dot with multiple leads

We show that an Anderson Hamiltonian describing a quantum dot connected to multiple leads is integrable. A general expression for the nonlinear conductance is obtained by combining the Bethe ansatz exact solution with Landauer-Buttiker theory. In the Kondo regime, a closed form expression is given for the matrix conductance at zero temperature and when all the leads are close to the symmetric point. A bias-induced splitting of the Kondo resonance is possible for three or more leads. Specifically, for N leads, with each at a different chemical potential, there can be N-1 Kondo peaks in the conductance.

Multiple tissue-specific promoters control expression of the murine tartrate-resistant acid phosphatase gene

Tartrate-resistant acid phosphatase (TRAP) is highly expressed in osteoclasts and in a subset of tissue macrophages and dendritic cells. It is expressed at lower levels in the parenchymal cells of the liver, glomerular mesangial cells of the kidney and pancreatic acinar cells. We have identified novel TRAP mRNAs that differ in their 5-untranslated region (5'-UTR) sequence, but align with the known murine TRAP mRNA from the first base of Exon 2. The novel 5'-UTRs represent alternative first exons located upstream of the known 5'-UTR. A similar genomic structure exists for the human TRAP gene with partial conservation of the exon and promoter sequences. Expression of the most distal 5'-UTR (Exon 1A) is restricted to adult bone and spleen tissue. Exon 1B is expressed primarily in tissues containing TRAP-positive nonhaematopoietic cells. The known TRAP 5'-UTR (Exon 1) is expressed in tissues characteristic of myeloid cell expression. In addition the Exon 1C promoter sequence is shown to comprise distinct transcription start regions, with an osteoclast-specific transcription initiation site identified downstream of a TATA-like element. Macrophages are shown to initiate transcription of the Exon 1C transcript from a purine-rich region located upstream of the osteoclast-specific transcription start point. The distinct expression patterns for each of the TRAP 5'-UTRs suggest that TRAP mRNA expression is regulated by the use of four alternative tissue- and cell-restricted promoters. (C) 2003 Elsevier Science B.V. All rights reserved.

Orientation of the genetic variance-covariance matrix and the fitness surface for multiple male sexually selected traits

Stabilizing selection has been predicted to change genetic variances and covariances so that the orientation of the genetic variance-covariance matrix (G) becomes aligned with the orientation of the fitness surface, but it is less clear how directional selection may change G. Here we develop statistical approaches to the comparison of G with vectors of linear and nonlinear selection. We apply these approaches to a set of male sexually selected cuticular hydrocarbons (CHCs) of Drosophila serrata. Even though male CHCs displayed substantial additive genetic variance, more than 99% of the genetic variance was orientated 74.9degrees away from the vector of linear sexual selection, suggesting that open-ended female preferences may greatly reduce genetic variation in male display traits. Although the orientation of G and the fitness surface were found to differ significantly, the similarity present in eigenstructure was a consequence of traits under weak linear selection and strong nonlinear ( convex) selection. Associating the eigenstructure of G with vectors of linear and nonlinear selection may provide a way of determining what long-term changes in G may be generated by the processes of natural and sexual selection.

Investigating genetic discrimination in Australia: Opportunities and challenges in the early stages

Genetic discrimination, defined as the differential treatment of individuals or their relatives on the basis of actual or presumed genetic differences, is an emerging issue of interest in academic, clinical, social and legal contexts. While its potential significance has been discussed widely, verified empirical data are scarce. Genetic discrimination is a complex phenomenon to describe and investigate, as evidenced by the recent Australian Law Reform Commission inquiry in Australia. The authors research project, which commenced in 2002, aims to document the multiple perspectives and experiences regarding genetic discrimination in Australia and inform future policy development and law reform. Data are being collected from consumers, employers, insurers and the legal system. Attempted verification of alleged accounts of genetic discrimination will be a novel feature of the research. This paper overviews the early stages of the research, including conceptual challenges and their methodological implications.

Maintaining and updating semantic context in schizophrenia: an investigation of the effects of multiple remote primes

Conflicting findings regarding the ability of people with schizophrenia to maintain and update semantic contexts have been due, arguably, to vagaries within the experimental design employed (e.g. whether strongly or remotely associated prime-target pairs have been used, what delay between the prime and the target was employed, and what proportion of related prime-target pairs appeared) or to characteristics of the participant cohort (e.g. medication status, chronicity of illness). The aim of the present study was to examine how people with schizophrenia maintain and update contextual information over an extended temporal window by using multiple primes that were either remotely associated or unrelated to the target. Fourteen participants with schizophrenia and 12 healthy matched controls were compared across two stimulus onset asynchronies (SOAs) (short and long) and two relatedness proportions (RP) (high and low) in a crossed design. Analysis of variance statistics revealed significant two- and three-way interactions between Group and SOA, Group and Condition, SOA and RP, and Group, SOA and RP. The participants with schizophrenia showed evidence of enhanced remote priming at the short SOA and low RP, combined with a reduction in the time course over which context could be maintained. There was some sensitivity to biasing contextual information at the short SOA, although the mechanism over which context served to update information appeared to be different from that in the controls. The participants with schizophrenia showed marked performance decrements at the long SOA (both low and high RP). Indices of remote priming at the short (but not the long) SOA correlated with both clinical ratings of thought disorder and with increasing length of illness. The results support and extend the hypothesis that schizophrenia is associated with concurrent increases in tonic dopamine activity and decreases in phasic dopamine activity. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

The challenges of abundance: epithelial junctions and small GTPase signalling

Small GTPases of the Ras superfamily play critical roles in epithelial biogenesis. Many key morphogenetic functions occur when small GTPases act at epithelial junctions, where they mediate an increasingly complex interplay between cell-cell adhesion molecules and fundamental cellular processes, such as cytoskeletal activity, polarity and trafficking. Important recent advances in this field include the role of additional members of the Ras superfamily in cell-cell contact stability and the capacity for polarity determinants to regulate small GTPase signalling. Interestingly, small GTPases may participate in the cross-talk between different adhesive receptors: in tissues classical cadherins can selectively regulate other junctions through cell signalling rather than through a global influence on cell-cell cohesion.

The multiple signals assessed by female satin bowerbirds: could they be used to narrow down females' choices of mates?

Female choice based on multiple male traits has been documented in many species but the functions of such multiple traits are still under debate. The satin bowerbird has a polygynous mating system in which males attract females to bowers for mating; females choose mates based on multiple aspects of males and their bowers. In this paper, we demonstrate that females use some cues to decide which males to examine closely and other cues to decide which males to mate with. Female visitation rates to bowers were significantly related to male size and the males' 'solitary' display rates, and, to a lesser extent, to the numbers of bower decorations. After controlling for female visitation rates, it was found that a male's mating success was significantly related to his size and the rate at which he 'painted' his bower with saliva and chewed up plant material.

Use of the EM algorithm to detect QTL affecting multiple-traits in an across half-sib family analysis

QTL detection experiments in livestock species commonly use the half-sib design. Each male is mated to a number of females, each female producing a limited number of progeny. Analysis consists of attempting to detect associations between phenotype and genotype measured on the progeny. When family sizes are limiting experimenters may wish to incorporate as much information as possible into a single analysis. However, combining information across sires is problematic because of incomplete linkage disequilibrium between the markers and the QTL in the population. This study describes formulae for obtaining MLEs via the expectation maximization (EM) algorithm for use in a multiple-trait, multiple-family analysis. A model specifying a QTL with only two alleles, and a common within sire error variance is assumed. Compared to single-family analyses, power can be improved up to fourfold with multi-family analyses. The accuracy and precision of QTL location estimates are also substantially improved. With small family sizes, the multi-family, multi-trait analyses reduce substantially, but not totally remove, biases in QTL effect estimates. In situations where multiple QTL alleles are segregating the multi-family analysis will average out the effects of the different QTL alleles.

On multiple solutions of the exterior neumann problem involving critical sobolev exponent

In this paper we consider the exterior Neumann problem involving a critical Sobolev exponent. We establish the existence of two solutions having a prescribed limit at infinity.