Observation of bright polariton solitons in a semiconductor microcavity

Microcavity polaritons are composite half-light half-matter quasi-particles, which have recently been demonstrated to exhibit rich physical properties, such as non-equilibrium Bose-Einstein condensation, parametric scattering and superfluidity. At the same time, polaritons have some important advantages over photons for information processing applications, since their excitonic component leads to weaker diffraction and stronger inter-particle interactions, implying, respectively, tighter localization and lower powers for nonlinear functionality. Here we present the first experimental observations of bright polariton solitons in a strongly coupled semiconductor microcavity. The polariton solitons are shown to be non-diffracting high density wavepackets, that are strongly localised in real space with a corresponding broad spectrum in momentum space. Unlike solitons known in other matter-wave systems such as Bose condensed ultracold atomic gases, they are non-equilibrium and rely on a balance between losses and external pumping. Microcavity polariton solitons are excited on picosecond timescales, and thus have significant benefits for ultrafast switching and transfer of information over their light only counterparts, semiconductor cavity lasers (VCSELs), which have only nanosecond response time

Epidemiology of neurodegenerative diseases in sub-Saharan Africa: a systematic review

BACKGROUND:Sub-Saharan African (SSA) countries are experiencing rapid transitions with increased life expectancy. As a result the burden of age-related conditions such as neurodegenerative diseases might be increasing. We conducted a systematic review of published studies on common neurodegenerative diseases, and HIV-related neurocognitive impairment in SSA, in order to identify research gaps and inform prevention and control solutions. METHODS: We searched MEDLINE via PubMed, 'Banque de Donnees de Sante Publique' and the database of the 'Institut d'Epidemiologie Neurologique et de Neurologie Tropicale' from inception to February 2013 for published original studies from SSA on neurodegenerative diseases and HIV-related neurocognitive impairment. Screening and data extraction were conducted by two investigators. Bibliographies and citations of eligible studies were investigated. RESULTS: In all 144 publications reporting on dementia (n=49 publications, mainly Alzheimer disease), Parkinsonism (PD, n=20), HIV-related neurocognitive impairment (n=47), Huntington disease (HD, n=19), amyotrophic lateral sclerosis (ALS, n=15), cerebellar degeneration (n=4) and Lewy body dementia (n=1). Of these studies, largely based on prevalent cases from retrospective data on urban populations, half originated from Nigeria and South Africa. The prevalence of dementia (Alzheimer disease) varied between <1% and 10.1% (0.7% and 5.6%) in population-based studies and from <1% to 47.8% in hospital-based studies. Incidence of dementia (Alzheimer disease) ranged from 8.7 to 21.8/1000/year (9.5 to 11.1), and major risk factors were advanced age and female sex. HIV-related neurocognitive impairment's prevalence (all from hospital-based studies) ranged from <1% to 80%. Population-based prevalence of PD and ALS varied from 10 to 235/100,000, and from 5 to 15/100,000 respectively while that for Huntington disease was 3.5/100,000. Equivalent figures for hospital based studies were the following: PD (0.41 to 7.2%), ALS (0.2 to 8.0/1000), and HD (0.2/100,000 to 46.0/100,000). CONCLUSIONS: The body of literature on neurodegenerative disorders in SSA is large with regard to dementia and HIV-related neurocognitive disorders but limited for other neurodegenerative disorders. Shortcomings include few population-based studies, heterogeneous diagnostic criteria and uneven representation of countries on the continent. There are important knowledge gaps that need urgent action, in order to prepare the sub-continent for the anticipated local surge in neurodegenerative diseases

The effects of aerobic, resistance, and combined exercise on metabolic control, inflammatory markers, adipocytokines, and muscle insulin signaling in patients with type 2 diabetes mellitus

The purpose of this study was to compare the effects of 3 different modalities of exercise on metabolic control, insulin resistance, inflammatory markers, adipocytoldnes, and tissue expression of insulin receptor substrate (IRS)-1 after 12 weeks of training among patients with type 2 diabetes mellitus. Forty-eight patients with type 2 diabetes mellitus were randomly assigned to 4 groups of training (3 times a week, 60 minutes per session): aerobic group (n = 12), resistance group (n = 12), combined (aerobic and resistance) group (n = 12), and control group (n = 12). Fasting and postprandial blood glucose, glycated hemoglobin, lipid profile, insulin resistance index (homeostasis model assessment of insulin resistance), adipocytokines (adiponectin, visfatin, and resistin), tumor necrosis factor, interleukin, and high-sensitivity C-reactive protein (hs-CRP) were measured at baseline and at the end of the study. Patients also underwent a muscle microbiopsy before and after training to quantify IRS-1 expression. All 4 groups displayed decreases in blood pressure, fasting plasma glucose, postprandial plasma glucose, lipid profile, and hs-CRP (P < .05); and there was no difference across the groups. After training, the IRS-1 expression increased by 65% in the resistance group (P < .05) and by 90% in the combined group (P < .01). Exercise training favorably affects glycemic parameters, lipid profile, blood pressure, and hs-CRP. In addition, resistance and combined training can increase IRS-1 expression. (C) 2011 Elsevier Inc. All rights reserved.60912441252Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG