Gauge field theory approach to spin transport in a 2D electron gas

We discuss the Pauli Hamiltonian including the spin-orbit interaction within an U(1) x SU(2) gauge theory interpretation, where the gauge symmetry appears to be broken. This interpretation offers new insight into the problem of spin currents in the condensed matter environment, and can be extended to Rashba and Dresselhaus spin-orbit interactions. We present a few outcomes of the present formulation: i) it automatically leads to zero spin conductivity, in contrast to predictions of Gauge symmetric treatments, ii) a topological quantization condition leading to voltage quantization follows, and iii) spin interferometers can be conceived in which, starting from a arbitrary incoming unpolarized spinor, it is always possible to construct a perfect spin filtering condition.Comment: Invited contribution to Statphys conference, June 2009, Lviv (Ukraine

Effect of a gum-based thickener on the safety of swallowing in patients with poststroke oropharyngeal dysphagia

Altres ajuts: This work has been supported by Danone Nutricia Research, Fundació Salut del Consorci Sanitari del Maresme, Furega (Fundació per a la Recerca en Gastroenterologia) and Centro de Investigación en Red en Enfermedades Hepáticas y Digestivas (CIBERehd).Background: Increasing viscosity with thickening agents is a valid therapeutic strategy for oropharyngeal dysphagia (OD). To assess the therapeutic effect of a xanthan gum-based thickener (Nutilis Clear) at six viscosities compared with thin liquid in poststroke OD (PSOD) patients. Methods: A total of 120 patients with PSOD were studied in this controlled, multiple-dose, fixed-order, and single-blind study using videofluoroscopy (VFSS). A series of boluses of 10 mL thin liquid and 2000, 1400, 800, 450, 250, and 150 mPa s viscosities were given in duplicate, interrupted in case of aspiration. We assessed the safety and efficacy of swallow and the kinematics of the swallow response. Key Results: A total of 41.2% patients had safe swallow at thin liquid which significantly increased for all viscosities from 71.9% at 150 mPa s to 95.6% at 1400 mPa s (P <.001). PAS score (3.7 ± 2.3) at thin liquid was also reduced by increasing bolus viscosity (P <.001). The prevalence of patients with aspiration at thin liquid was 17.5% and decreased at all viscosities (P <.01), except at 150 mPa s. Increasing viscosity shortened time to laryngeal vestibule closure (LVC) at all viscosities (P <.01) and reduced bolus velocity at ≥450 mPa s (P <.05). The prevalence of patients with pharyngeal residue at each viscosity 37.7%-44.7% was similar to that at thin liquid (41.2%). Conclusions and Inferences: The prevalence of unsafe swallow with thin liquids is very high in PSOD. Increasing shear bolus viscosity with this xanthan gum-based thickener significantly increased the safety of swallow in patients with PSOD in a viscosity-dependent manner without increasing the prevalence of pharyngeal residue

Arachidin-1 and Arachidin-3 Modulation of Rotavirus-infected MA104 Cells

Rotavirus (RV) causes severe life-threatening diarrhea in young children and immunocompromised individuals. There are several licensed attenuated vaccines for young children, but there are no vaccines or antiviral therapeutics for immunocompromised patients of any age. Previously, our laboratory demonstrated that arachidin 1 (A1) and arachidin 3 (A3) decreases the number of infectious simian RV particles and RV non-structural protein 4 (NSP4) in a human intestinal cell line which suggests effects on RV replication. This study examined the effects of the arachidins on the human RV (Wa)-infected African green monkey kidney cell line, MA104. The addition of either A1 or A3 did not decrease the viability of MA104 cells, however plaque forming assays measured significant decreases in the number of infectious RV particles with the addition of the arachidins. Correspondingly, western blot analyses revealed a change in the presence of VP6 and NSP4 (structural and nonstructural RV proteins, respectively). This implies that like the simian RV, Wa replication is also affected by both A1 and A3. Additionally, tunable resistive pulse sensing technology (TRPS) measured changes in the population distribution of released nanoparticles between 60-140 nanometers. Additionally, TEM morphometric analyses showed ultrastructural changed in RV-infected cells treated with A1 or A3. This included nucleus to cytoplasm ratios that were determined by TEM and whole cell fluorescent assays that disclosed significant nuclear size alterations with the addition of RV which implied modifications of the apoptosis and autophagy pathways. Moreover, the increased presence of autophagic vesicles seen with RV+A1 reinforced the model of a switch from the apoptosis to the autophagy pathway. In addition, immunoblot assays reveal the presence of cannabinoid 1 and 2 receptors on MA104 cells. These receptors bind A1 and A3 and are important in signaling in the endocannabinoid system. This implies a role for Witcher et al.: Arachidin-1 and Arachidin-3 Modulation of Rotavirus-infected MA10 2 A1 and A3 in modulating cannabinoid receptor cell signaling in RV-infected cells which indicates a mechanism of action of A1 and A3 with potential RV therapeutic activity

Fractional oscillator process with two indices

We introduce a new fractional oscillator process which can be obtained as solution of a stochastic differential equation with two fractional orders. Basic properties such as fractal dimension and short range dependence of the process are studied by considering the asymptotic properties of its covariance function. The fluctuation--dissipation relation of the process is investigated. The fractional oscillator process can be regarded as one-dimensional fractional Euclidean Klein-Gordon field, which can be obtained by applying the Parisi-Wu stochastic quantization method to a nonlocal Euclidean action. The Casimir energy associated with the fractional field at positive temperature is calculated by using the zeta function regularization technique.Comment: 32 page

The Dynamical Behaviour of Test Particles in a Quasi-Spherical Spacetime and the Physical Meaning of Superenergy

We calculate the instantaneous proper radial acceleration of test particles (as measured by a locally defined Lorentzian observer) in a Weyl spacetime, close to the horizon. As expected from the Israel theorem, there appear some bifurcations with respect to the spherically symmetric case (Schwarzschild), which are explained in terms of the behaviour of the superenergy, bringing out the physical relevance of this quantity in the study of general relativistic systems.Comment: 14 pages, Latex. 4 figures. New references added. Typos corrected. To appear in Int. J. Theor. Phy

Neighborhood Health Care Access and Sexually Transmitted Infections among Women in the Southern United States: A Cross-Sectional Multilevel Analysis

Introduction: The United States has experienced an increase in reportable sexually transmitted infections (STIs) while simultaneously experiencing a decline in safety net services for STI testing and treatment. This multilevel study assessed relationships between neighborhood-level access to health care and STIs among a predominantly Human Immunodeficiency Virus (HIV)-seropositive cohort of women living in the south. Methods: This cross-sectional multilevel analysis included baseline data from HIV-seropositive and HIV-seronegative women enrolled in the Women's Interagency HIV Study sites in Alabama, Florida, Georgia, Mississippi, and North Carolina between 2013 and 2015 (N = 666). Administrative data (eg, United States Census) described health care access (eg, percentage of residents with a primary care provider, percentage of residents with health insurance) in the census tracts where women lived. Sexually transmitted infections (chlamydia, gonorrhea, trichomoniasis, or early syphilis) were diagnosed using laboratory testing. Generalized estimating equations were used to determine relationships between tractlevel characteristics and STIs. Analyses were conducted using SAS 9.4. Results: Seventy percent of participants were HIV-seropositive. Eleven percent of participants had an STI. A 4-unit increase in the percentage of residents with a primary care provider was associated with 39% lower STI risk (risk ratio, 0.61, 95%confidence interval, 0.38-0.99). The percentage of tract residents with health insurance was not associated with STIs (risk ratio, 0.98, 95% confidence interval, 0.91-1.05). Relationships did not vary by HIV status. Conclusions: Greater neighborhood health care access was associated with fewer STIs. Research should establish the causality of this relationship and pathways through which neighborhood health care access influences STIs. Structural interventions and programs increasing linkage to care may reduce STIs

Neuroimaging Evidence of Major Morpho-Anatomical and Functional Abnormalities in the BTBR T+TF/J Mouse Model of Autism

BTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations

Taxing the Informal Economy: The Current State of Knowledge and Agendas for Future Research

This paper reviews the literature on taxation of the informal economy, taking stock of key debates and drawing attention to recent innovations. Conventionally, the debate on whether to tax has frequently focused on the limited revenue potential, high cost of collection, and potentially adverse impact on small firms. Recent arguments have increasingly emphasised the more indirect benefits of informal taxation in relation to economic growth, broader tax compliance, and governance. More research is needed, we argue, into the relevant costs and benefits for all, including quasi-voluntary compliance, political and administrative incentives for reform, and citizen-state bargaining over taxation