575 research outputs found
Hidden Orbital Order in
When matter is cooled from high temperatures, collective instabilities
develop amongst its constituent particles that lead to new kinds of order. An
anomaly in the specific heat is a classic signature of this phenomenon. Usually
the associated order is easily identified, but sometimes its nature remains
elusive. The heavy fermion metal is one such example, where the
order responsible for the sharp specific heat anomaly at has
remained unidentified despite more than seventeen years of effort. In
, the coexistence of large electron-electron repulsion and
antiferromagnetic fluctuations in leads to an almost incompressible
heavy electron fluid, where anisotropically paired quasiparticle states are
energetically favored. In this paper we use these insights to develop a
detailed proposal for the hidden order in . We show that
incommensurate orbital antiferromagnetism, associated with circulating currents
between the uranium ions, can account for the local fields and entropy loss
observed at the transition; furthermore we make detailed predictions for
neutron scattering measurements
NetPyNE, a tool for data-driven multiscale modeling of brain circuits.
Biophysical modeling of neuronal networks helps to integrate and interpret rapidly growing and disparate experimental datasets at multiple scales. The NetPyNE tool (www.netpyne.org) provides both programmatic and graphical interfaces to develop data-driven multiscale network models in NEURON. NetPyNE clearly separates model parameters from implementation code. Users provide specifications at a high level via a standardized declarative language, for example connectivity rules, to create millions of cell-to-cell connections. NetPyNE then enables users to generate the NEURON network, run efficiently parallelized simulations, optimize and explore network parameters through automated batch runs, and use built-in functions for visualization and analysis - connectivity matrices, voltage traces, spike raster plots, local field potentials, and information theoretic measures. NetPyNE also facilitates model sharing by exporting and importing standardized formats (NeuroML and SONATA). NetPyNE is already being used to teach computational neuroscience students and by modelers to investigate brain regions and phenomena
Transgenic Overexpression of Active Calcineurin in β-Cells Results in Decreased β-Cell Mass and Hyperglycemia
BACKGROUND:Glucose modulates beta-cell mass and function through an initial depolarization and Ca(2+) influx, which then triggers a number of growth regulating signaling pathways. One of the most important downstream effectors in Ca(2+) signaling is the calcium/Calmodulin activated serine threonine phosphatase, calcineurin. Recent evidence suggests that calcineurin/NFAT is essential for beta-cell proliferation, and that in its absence loss of beta-cells results in diabetes. We hypothesized that in contrast, activation of calcineurin might result in expansion of beta-cell mass and resistance to diabetes. METHODOLOGY/PRINCIPAL FINDINGS:To determine the role of activation of calcineurin signaling in the regulation of pancreatic beta-cell mass and proliferation, we created mice that expressed a constitutively active form of calcineurin under the insulin gene promoter (caCn(RIP)). To our surprise, these mice exhibited glucose intolerance. In vitro studies demonstrated that while the second phase of Insulin secretion is enhanced, the overall insulin secretory response was conserved. Islet morphometric studies demonstrated decreased beta-cell mass suggesting that this was a major component responsible for altered Insulin secretion and glucose intolerance in caCn(RIP) mice. The reduced beta-cell mass was accompanied by decreased proliferation and enhanced apoptosis. CONCLUSIONS:Our studies identify calcineurin as an important factor in controlling glucose homeostasis and indicate that chronic depolarization leading to increased calcineurin activity may contribute, along with other genetic and environmental factors, to beta-cell dysfunction and diabetes
Paternal obesity is associated with IGF2 hypomethylation in newborns: results from a Newborn Epigenetics Study (NEST) cohort
Data from epidemiological and animal model studies suggest that nutrition during pregnancy may affect the health status of subsequent generations. These transgenerational effects are now being explained by disruptions at the level of the epigenetic machinery. Besides in vitro environmental exposures, the possible impact on the reprogramming of methylation profiles at imprinted genes at a much earlier time point, such as during spermatogenesis or oogenesis, has not previously been considered. In this study, our aim was to determine associations between preconceptional obesity and DNA methylation profiles in the offspring, particularly at the differentially methylated regions (DMRs) of the imprinted Insulin-like Growth Factor 2 (IGF2) gene
Collagenous Fibroma (Desmoplastic Fibroblastoma) of the Neck Presenting with Neurological Symptoms
Collagenous fibromas are rare fibrous soft tissue tumours that usually arise in subcutaneous tissue or skeletal muscle at a variety of anatomical sites. These lesions commonly present as painless, slow-growing mobile masses. We describe a unique case of a 41-year-old woman presenting with a posterior neck swelling and longstanding history of severe ongoing pain in the right scapular region, shoulder and neck, weakness of the palmar grip and limited right lateral neck flexion and rotation. A history of trauma to the right neck in adolescence was noted. Histological analysis revealed a paucicellular lesion with spindle and stellate-shaped fibroblasts involving the cervical nerve roots, typical of collagenous fibroma. In a literature search on Medline and Pubmed, we found no reported cases of collagenous fibromas presenting with neurological symptoms. This report highlights the potential of these lesions to present with neurological symptoms due to infiltration of surrounding tissues, and that preceding trauma may contribute to the aetiology
Evaluating the best time to intervene acute liver failure in rat models induced by d-galactosamine
The prevalence of suicidal ideation identified by the Edinburgh Postnatal Depression Scale in postpartum women in primary care: findings from the RESPOND trial
<p>1 Abstract</p> <p>1.1 Background</p> <p>Suicide is a leading cause of perinatal maternal deaths in industrialised countries but there has been little research to investigate prevalence or correlates of postpartum suicidality. The Edinburgh Postnatal Depression Scale is widely used in primary and maternity services to screen for perinatal depressive disorders, and includes a question on suicidal ideation (question 10). We aimed to investigate the prevalence, persistence and correlates of suicidal thoughts in postpartum women in the context of a randomised controlled trial of treatments for postnatal depression.</p> <p>1.2 Methods</p> <p>Women in primary care were sent postal questionnaires at 6 weeks postpartum to screen for postnatal depression before recruitment into an RCT. The Edinburgh Postnatal Depression Scale (EPDS) was used to screen for postnatal depression and in those with high levels of symptoms, a home visit with a standardised psychiatric interview was carried out using the Clinical Interview Schedule-Revised version (CIS-R). Other socio-demographic and clinical variables were measured, including functioning (SF12) and quality of the marital relationship (GRIMS). Women who entered the trial were followed up for 18 weeks.</p> <p>1.3 Results</p> <p>9% of 4,150 women who completed the EPDS question relating to suicidal ideation reported some suicidal ideation (including hardly ever); 4% reported that the thought of harming themselves had occurred to them sometimes or quite often. In women who entered the randomised trial and completed the EPDS question relating to suicidal ideation (n = 253), suicidal ideation was associated with younger age, higher parity and higher levels of depressive symptoms in the multivariate analysis. Endorsement of 'yes, quite often' to question 10 on the EPDS was associated with affirming at least two CIS-R items on suicidality. We found no association between suicidal ideation and SF-12 physical or mental health or the EPDS total score at 18 weeks.</p> <p>1.4 Conclusions</p> <p>Healthcare professionals using the EPDS should be aware of the significant suicidality that is likely to be present in women endorsing 'yes, quite often' to question 10 of the EPDS. However, suicidal ideation does not appear to predict poor outcomes in women being treated for postnatal depression.</p> <p>Trial registration</p> <p>Current Controlled Trials <a href="http://www.controlled-trials.com/ISRCTN16479417">ISRCTN16479417</a>.</p
Dynamical Boson Stars
The idea of stable, localized bundles of energy has strong appeal as a model
for particles. In the 1950s John Wheeler envisioned such bundles as smooth
configurations of electromagnetic energy that he called {\em geons}, but none
were found. Instead, particle-like solutions were found in the late 1960s with
the addition of a scalar field, and these were given the name {\em boson
stars}. Since then, boson stars find use in a wide variety of models as sources
of dark matter, as black hole mimickers, in simple models of binary systems,
and as a tool in finding black holes in higher dimensions with only a single
killing vector. We discuss important varieties of boson stars, their dynamic
properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in
Relativity; major revision in 201
The importance of parameter choice in modelling dynamics of the eye lens
The lens provides refractive power to the eye and is capable of altering ocular focus in response to visual demand. This capacity diminishes with age. Current biomedical technologies, which seek to design an implant lens capable of replicating the function of the biological lens, are unable as yet to provide such an implant with the requisite optical quality or ability to change the focussing power of the eye. This is because the mechanism of altering focus, termed accommodation, is not fully understood and seemingly conflicting theories require experimental support which is difficult to obtain from the living eye. This investigation presents finite element models of the eye lens based on data from human lenses aged 16 and 35 years that consider the influence of various modelling parameters, including material properties, a wide range of angles of force application and capsular thickness. Results from axisymmetric models show that the anterior and posterior zonules may have a greater impact on shape change than the equatorial zonule and that choice of capsular thickness values can influence the results from modelled simulations
Cystic appearance of low-grade endometrial stromal sarcoma in the right atrium: case report
A 71-year-old woman presented with a right adnexal solid mass invading the right gonadal vein and inferior vena cava up to the hepatic veins revealed by CT and confirmed by MRI. A thin-walled cyst and a solid mass were unexpectedly found in the right atrium by transesophageal echocardiography (TEE) in the operating room. Using color Doppler and air bubbles as contrast material a circumscribed cyst was confirmed and localized close to the IVC. The cyst was connected to the mass in the inferior vena cava. The tumor, including the cyst, was removed without using cardiopulmonary bypass and described as a low-grade endometrial stromal sarcoma, a rare slowly growing tumor. This is the first TEE description of endometrial stromal sarcoma manifesting as a right atrial cyst
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