3,085 research outputs found

    Collective Excitations of Holographic Quantum Liquids in a Magnetic Field

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    We use holography to study N=4 supersymmetric SU(Nc) Yang-Mills theory in the large-Nc and large-coupling limits coupled to a number Nf << Nc of (n+1)-dimensional massless supersymmetric hypermultiplets in the Nc representation of SU(Nc), with n=2,3. We introduce a temperature T, a baryon number chemical potential mu, and a baryon number magnetic field B, and work in a regime with mu >> T,\sqrt{B}. We study the collective excitations of these holographic quantum liquids by computing the poles in the retarded Green's function of the baryon number charge density operator and the associated peaks in the spectral function. We focus on the evolution of the collective excitations as we increase the frequency relative to T, i.e. the hydrodynamic/collisionless crossover. We find that for all B, at low frequencies the tallest peak in the spectral function is associated with hydrodynamic charge diffusion. At high frequencies the tallest peak is associated with a sound mode similar to the zero sound mode in the collisionless regime of a Landau Fermi liquid. The sound mode has a gap proportional to B, and as a result for intermediate frequencies and for B sufficiently large compared to T the spectral function is strongly suppressed. We find that the hydrodynamic/collisionless crossover occurs at a frequency that is approximately B-independent.Comment: 45 pages, 8 png and 47 pdf images in 22 figure

    A Bayesian explanation of the 'Uncanny Valley' effect and related psychological phenomena

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    There are a number of psychological phenomena in which dramatic emotional responses are evoked by seemingly innocuous perceptual stimuli. A well known example is the ‘uncanny valley’ effect whereby a near human-looking artifact can trigger feelings of eeriness and repulsion. Although such phenomena are reasonably well documented, there is no quantitative explanation for the findings and no mathematical model that is capable of predicting such behavior. Here I show (using a Bayesian model of categorical perception) that differential perceptual distortion arising from stimuli containing conflicting cues can give rise to a perceptual tension at category boundaries that could account for these phenomena. The model is not only the first quantitative explanation of the uncanny valley effect, but it may also provide a mathematical explanation for a range of social situations in which conflicting cues give rise to negative, fearful or even violent reactions

    Friedreich ataxia patient tissues exhibit increased 5-hydroxymethylcytosine modification and decreased CTCF binding at the FXN locus

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    © 2013 Al-Mahdawi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use,distribution, and reproduction in any medium, provided the original author and source are credited.This article has been made available through the Brunel Open Access Publishing Fund.Friedreich ataxia (FRDA) is caused by a homozygous GAA repeat expansion mutation within intron 1 of the FXN gene, which induces epigenetic changes and FXN gene silencing. Bisulfite sequencing studies have identified 5-methylcytosine (5 mC) DNA methylation as one of the epigenetic changes that may be involved in this process. However, analysis of samples by bisulfite sequencing is a time-consuming procedure. In addition, it has recently been shown that 5-hydroxymethylcytosine (5 hmC) is also present in mammalian DNA, and bisulfite sequencing cannot distinguish between 5 hmC and 5 mC.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement number 242193/EFACTS (CS), the Wellcome Trust [089757] (SA) and Ataxia UK (RMP) to MAP

    Relationship of cognitive function in patients with schizophrenia in remission to disability: a cross-sectional study in an Indian sample

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    Background: Cognitive deficits in various domains have been consistently replicated in patients with schizophrenia. Most studies looking at the relationship between cognitive dysfunction and functional disability are from developed countries. Studies from developing countries are few. The purpose of the present study was to compare the neurocognitive function in patients with schizophrenia who were in remission with that of normal controls and to determine if there is a relationship between measures of cognition and functional disability. &lt;p/&gt;Methods: This study was conducted in the Psychiatric Unit of a General Hospital in Mumbai, India. Cognitive function in 25 patients with schizophrenia in remission was compared to 25 normal controls. Remission was confirmed using the brief psychiatric rating scale (BPRS) and scale for the assessment of negative symptoms (SANS). Subjects were administered a battery of cognitive tests covering aspects of memory, executive function and attention. The results obtained were compared between the groups. Correlation analysis was used to look for relationship between illness factors, cognitive function and disability measured using the Indian disability evaluation and assessment scale. &lt;p/&gt;Results: Patients with schizophrenia showed significant deficits on tests of attention, concentration, verbal and visual memory and tests of frontal lobe/executive function. They fared worse on almost all the tests administered compared to normal controls. No relationship was found between age, duration of illness, number of years of education and cognitive function. In addition, we did not find a statistically significant relationship between cognitive function and scores on the disability scale. &lt;p/&gt;Conclusion: The data suggests that persistent cognitive deficits are seen in patients with schizophrenia under remission. The cognitive deficits were not associated with symptomatology and functional disability. It is possible that various factors such as employment and family support reduce disability due to schizophrenia in developing countries like India. Further studies from developing countries are required to explore the relationship between cognitive deficits, functional outcome and the role of socio-cultural variables as protective factors

    Circulating markers of arterial thrombosis and late-stage age-related macular degeneration: a case-control study.

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    PURPOSE: The aim of this study was to examine the relation of late-stage age-related macular degeneration (AMD) with markers of systemic atherothrombosis. METHODS: A hospital-based case-control study of AMD was undertaken in London, UK. Cases of AMD (n=81) and controls (n=77) were group matched for age and sex. Standard protocols were used for colour fundus photography and to classify AMD; physical examination included height, weight, history of or treatment for vascular-related diseases and smoking status. Blood samples were taken for measurement of fibrinogen, factor VIIc (FVIIc), factor VIIIc, prothrombin fragment F1.2 (F1.2), tissue plasminogen activator, and von Willebrand factor. Odds ratios from logistic regression analyses of each atherothrombotic marker with AMD were adjusted for age, sex, and established cardiovascular disease risk factors, including smoking, blood pressure, body mass index, and total cholesterol. RESULTS: After adjustment FVIIc and possibly F1.2 were inversely associated with the risk of AMD; per 1 standard deviation increase in these markers the odds ratio were, respectively, 0.62 (95% confidence interval 0.40, 0.95) and 0.71 (0.46, 1.09). None of the other atherothrombotic risk factors appeared to be related to AMD status. There was weak evidence that aspirin is associated with a lower risk of AMD. CONCLUSIONS: This study does not provide strong evidence of associations between AMD and systematic markers of arterial thrombosis, but the potential effects of FVIIc, and F1.2 are worthy of further investigation

    A traditional Chinese medicine versus Western combination therapy in the treatment of rheumatoid arthritis: two-stage study protocol for a randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>The common randomized controlled trial design has distinct limitations when applied to Chinese medicine, because Chinese medicine identifies and treats 'Chinese medicine patterns' rather than diagnosed diseases. Chinese medicine patterns are a group of associated symptoms, tongue appearances and pulse characteristics. These limitations could be overcome by developing new strategies to evaluate the effect of Chinese medicine. The idea behind pattern-based efficacy evaluations may optimize clinical trial design by identifying the responsiveness-related Chinese medicine patterns.</p> <p>Methods/Design</p> <p>This is a two-stage multi-center trial of Chinese herbal medicine for the management of rheumatoid arthritis. The stage one trial is an open-label trial and aims to explore what groups of Chinese medicine information (such as symptoms) correlates with better efficacy, and the stage two trial is a randomized, controlled, double-blind, double-dummy clinical trial that incorporates the efficacy-related information identified in the stage-one trial into the inclusion criteria.</p> <p>Discussion</p> <p>The indication of a Chinese herbal formula is a specific Chinese medicine pattern and not a single disease and stratifying a disease into several patterns with a group of symptoms is a feasible procedure in clinical trials. This study is the first to investigate whether this approach in the design of Chinese herbal medicine trials can improve responses.</p> <p>Trial registration</p> <p>ChiCTR-TRC-10000989</p

    A nodulo-cystic eumycetoma caused by Pyrenochaeta romeroi in a renal transplant recipient: A case report

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    <p>Abstract</p> <p>Introduction</p> <p><it>Pyrenochaeta romeroi </it>(<it>P. romeroi</it>) is a saprophytic fungus found in soil and plants. The fungal spores can be introduced into deeper tissues by trauma. It causes eumycetoma, which affects skin and subcutaneous tissues.</p> <p>Case presentation</p> <p>A 57-year-old South Asian man presented with a painless, nodular lesion (1 cm × 0.5 cm) on the left knee. He had had a renal transplant eight months earlier for end-stage renal failure. The patient was on tacrolimus, mycophenolate mofetil and prednisolone for immunosuppression. The lesion had progressed dramatically (to 5 cm × 5 cm) despite antibiotic treatment. The size and location of the lesion was severely affecting his quality of life, so an excision biopsy was performed. Nuclear ribosomal repeat-region sequencing confirmed the causative organism as <it>P. romeroi</it>. An <it>in vitro </it>antifungal susceptibility test demonstrated that <it>P. romeroi </it>was sensitive to voriconazole. Following a successful surgical removal, voriconazole was continued orally for two months.</p> <p>Conclusion</p> <p>To the best of our knowledge, we are reporting the first case of Eumycetoma caused by <it>P. romeroi </it>in a renal transplant recipient. Physicians should be aware of this rare fungal disease in transplant recipients. We recommend a combination of medical and surgical management in these immunosuppressed patients.</p
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