317 research outputs found
Normal metal to ferromagnetic superconductor tunneling
We study the point-contact tunneling between normal metal and ferromagnetic
superconductor. In the case of magnon-induced pairing the tunneling conductance
is continuous and smooth function of the applied voltage. For small values of
the applied voltage the Ohm law holds. We show that one can obtain the
magnetization and the superconducting order parameter from the tunneling
conduc- tance. In the case of paramagnon-induced superconductivity the
tunneling does not depend on the magnetization. We argue that tunneling
experiment can unambiguously determine the correct pairing mechanism in the
ferromagnetic superconductors.Comment: 6 pages, 4 figur
Potential conservation of circadian clock proteins in the phylum Nematoda as revealed by bioinformatic searches
Although several circadian rhythms have been described in C. elegans, its molecular clock remains elusive. In this work we employed a novel bioinformatic approach, applying probabilistic methodologies, to search for circadian clock proteins of several of the best studied circadian model organisms of different taxa (Mus musculus, Drosophila melanogaster, Neurospora crassa, Arabidopsis thaliana and Synechoccocus elongatus) in the proteomes of C. elegans and other members of the phylum Nematoda. With this approach we found that the Nematoda contain proteins most related to the core and accessory proteins of the insect and mammalian clocks, which provide new insights into the nematode clock and the evolution of the circadian system.Fil: Romanowski, Andrés. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones BioquÃmicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones BioquÃmicas de Buenos Aires; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; ArgentinaFil: Garavaglia, MatÃas Javier. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Goya, MarÃa Eugenia. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Ghiringhelli, Pablo Daniel. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de Ing.genética y Biolog.molecular y Celular. Area Virus de Insectos; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Golombek, Diego Andres. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
Incompatibilities Involving Yeast Mismatch Repair Genes: A Role for Genetic Modifiers and Implications for Disease Penetrance and Variation in Genomic Mutation Rates
Genetic background effects underlie the penetrance of most genetically determined phenotypes, including human diseases. To explore how such effects can modify a mutant phenotype in a genetically tractable system, we examined an incompatibility involving the MLH1 and PMS1 mismatch repair genes using a large population sample of geographically and ecologically diverse Saccharomyces cerevisiae strains. The mismatch repair incompatibility segregates into naturally occurring yeast strains, with no strain bearing the deleterious combination. In assays measuring the mutator phenotype conferred by different combinations of MLH1 and PMS1 from these strains, we observed a mutator phenotype only in combinations predicted to be incompatible. Surprisingly, intragenic modifiers could be mapped that specifically altered the strength of the incompatibility over a 20-fold range. Together, these observations provide a powerful model in which to understand the basis of disease penetrance and how such genetic variation, created through mating, could result in new mutations that could be the raw material of adaptive evolution in yeast populations
Circulating Microbial Products and Acute Phase Proteins as Markers of Pathogenesis in Lymphatic Filarial Disease
Lymphatic filariasis can be associated with development of serious pathology in the form of lymphedema, hydrocele, and elephantiasis in a subset of infected patients. Dysregulated host inflammatory responses leading to systemic immune activation are thought to play a central role in filarial disease pathogenesis. We measured the plasma levels of microbial translocation markers, acute phase proteins, and inflammatory cytokines in individuals with chronic filarial pathology with (CP Ag+) or without (CP Ag−) active infection; with clinically asymptomatic infections (INF); and in those without infection (endemic normal [EN]). Comparisons between the two actively infected groups (CP Ag+ compared to INF) and those without active infection (CP Ag− compared to EN) were used preliminarily to identify markers of pathogenesis. Thereafter, we tested for group effects among all the four groups using linear models on the log transformed responses of the markers. Our data suggest that circulating levels of microbial translocation products (lipopolysaccharide and LPS-binding protein), acute phase proteins (haptoglobin and serum amyloid protein-A), and inflammatory cytokines (IL-1β, IL-12, and TNF-α) are associated with pathogenesis of disease in lymphatic filarial infection and implicate an important role for circulating microbial products and acute phase proteins
The fitness consequences of inbreeding in natural populations and their implications for species conservation – a systematic map
Background: Threatened species often have small and isolated populations where mating among relatives can
result in inbreeding depression increasing extinction risk. Effective management is hampered by a lack of syntheses
summarising the magnitude of, and variation in inbreeding depression. Here we describe the nature and scope
of the literature examining phenotypic/fitness consequences of inbreeding, to provide a foundation for future
syntheses and management.
Methods: We searched the literature for articles documenting the impact of inbreeding in natural populations.
Article titles, abstracts and full-texts were assessed against a priori defined criteria, and information relating to study
design, quality and other factors that may influence inbreeding responses (e.g. population size) was extracted from
relevant articles.
Results: The searches identified 11457 articles, of which 614 were assessed as relevant and included in the systematic
map (corresponding to 703 distinct studies). Most studies (663) assessed within-population inbreeding resulting from
self-fertilisation or consanguineous pairings, while 118 studies assessed among-population inbreeding due to drift load.
Plants were the most studied taxon (469 studies) followed by insects (52 studies) and birds (43 studies). Most studies
investigated the effects of inbreeding on components of fitness (e.g. survival or fecundity; 648 studies) but measurements
were typically under laboratory/greenhouse conditions (486 studies). Observations were also often restricted to the first
inbred generation (607 studies) and studies frequently lacked contextual information (e.g. population size).
Conclusions: Our systematic map describes the scope and quality of the evidence describing the phenotypic
consequences of inbreeding. The map reveals substantial evidence relating to inbreeding responses exists,
but highlights information is still limited for some aspects, including the effects of multiple generations of
inbreeding. The systematic map allowed us to define several conservation-relevant questions, where sufficient
data exists to support systematic reviews, e.g. How do inbreeding responses vary with population size? However,
we found that such syntheses are likely to be constrained by incomplete reporting of critical contextual information.
Our systematic map employed the same rigorous literature assessment methods as systematic review, including a
novel survey of study quality and thus provides a robust foundation to guide future research and syntheses seeking to
inform conservation decision-making
Cosmic acceleration and phantom crossing in -gravity
In this paper, we propose two new models in gravity to realize
universe acceleration and phantom crossing due to dark torsion in the
formalism. The model parameters are constrained and the observational test are
discussed. The best fit results favors an accelerating universe with possible
phantom crossing in the near past or future followed respectively by matter and
radiation dominated era.Comment: 20 pages, 18 figures, Will appear in Astrophys Space Sc
A systematic review of different models of home and community care services for older persons
<p>Abstract</p> <p>Background</p> <p>Costs and consumer preference have led to a shift from the long-term institutional care of aged older people to home and community based care. The aim of this review is to evaluate the outcomes of case managed, integrated or consumer directed home and community care services for older persons, including those with dementia.</p> <p>Methods</p> <p>A systematic review was conducted of non-medical home and community care services for frail older persons. MEDLINE, PsycINFO, CINAHL, AgeLine, Scopus and PubMed were searched from 1994 to May 2009. Two researchers independently reviewed search results.</p> <p>Results</p> <p>Thirty five papers were included in this review. Evidence from randomized controlled trials showed that case management improves function and appropriate use of medications, increases use of community services and reduces nursing home admission. Evidence, mostly from non-randomized trials, showed that integrated care increases service use; randomized trials reported that integrated care does not improve clinical outcomes. The lowest quality evidence was for consumer directed care which appears to increase satisfaction with care and community service use but has little effect on clinical outcomes. Studies were heterogeneous in methodology and results were not consistent.</p> <p>Conclusions</p> <p>The outcomes of each model of care differ and correspond to the model's focus. Combining key elements of all three models may maximize outcomes.</p
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