ZnSe/GaAs(001) heterostructures with defected interfaces: structural, thermodynamic and electronic properties

We have performed accurate \emph{ab--initio} pseudopotential calculations for the structural and electronic properties of ZnSe/GaAs(001) heterostructures with interface configurations accounting for charge neutrality prescriptions. Beside the simplest configurations with atomic interdiffusion we consider also some configurations characterized by As depletion and cation vacancies, motivated by the recent successfull growth of ZnSe/GaAs pseudomorphic structures with minimum stacking fault density characterized by the presence of a defected (Zn,Ga)Se alloy in the interface region. We find that--under particular thermodynamic conditions--some defected configurations are favoured with respect to undefected ones with simple anion or cation mixing, and that the calculated band offsets for some defected structures are compatible with those measured. Although it is not possible to extract indications about the precise interface composition and vacancy concentration, our results support the experimental indication of (Zn,Ga)Se defected compounds in high-quality ZnSe/GaAs(001) heterojunctions with low native stacking fault density. The range of measured band offset suggests that different atoms at interfaces rearrange, with possible presence of vacancies, in such a way that not only local charges but also ionic dipoles are vanishing.Comment: 26 pages. 5 figures, revised version, in press (Physical Review B

Chronic alcohol ingestion exacerbates skeletal muscle myopathy in HIV-1 transgenic rats

<p>Abstract</p> <p>Background</p> <p>Separately, chronic alcohol ingestion and HIV-1 infection are associated with severe skeletal muscle derangements, including atrophy and wasting, weakness, and fatigue. One prospective cohort study reported that 41% of HIV-infected patients met the criteria for alcoholism, however; few reports exist on the co-morbid effects of these two disease processes on skeletal muscle homeostasis. Thus, we analyzed the atrophic effects of chronic alcohol ingestion in HIV-1 transgenic rats and identified alterations to several catabolic and anabolic factors.</p> <p>Findings</p> <p>Relative plantaris mass, total protein content, and fiber cross-sectional area were reduced in each experimental group compared to healthy, control-fed rats. Alcohol abuse further reduced plantaris fiber area in HIV-1 transgenic rats. Consistent with previous reports, gene levels of myostatin and its receptor activin IIB were not increased in HIV-1 transgenic rat muscle. However, myostatin and activin IIB were induced in healthy and HIV-1 transgenic rats fed alcohol for 12 weeks. Catabolic signaling factors such as TGFβ₁, TNFα, and phospho-p38/total-p38 were increased in all groups compared to controls. There was no effect on IL-6, leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), or ciliary neurotrophic factor (CNTF) in control-fed, transgenic rats. However, the co-morbidity of chronic alcohol abuse and HIV-1-related protein expression decreased expression of the two anabolic factors, CT-1 and CNTF.</p> <p>Conclusions</p> <p>Consistent with previous reports, alcohol abuse accentuated skeletal muscle atrophy in an animal model of HIV/AIDS. While some catabolic pathways known to drive alcoholic or HIV-1-associated myopathies were also elevated in this co-morbid model (e.g., TGFβ₁), consistent expression patterns were not apparent. Thus, specific alterations to signaling mechanisms such as the induction of the myostatin/activin IIB system or reductions in growth factor signaling via CT-1- and CNTF-dependent mechanisms may play larger roles in the regulation of muscle mass in alcoholic, HIV-1 models.</p

Resonant spin-dependent electron coupling in a III-V/II-VI heterovalent double quantum well

We report on design, fabrication, and magnetooptical studies of a III-V/II-VI hybrid structure containing a GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum well (QW). The structure design allows one to tune the QW levels into the resonance, thus facilitating penetration of the electron wave function from the diluted magnetic semiconductor ZnCdMnSe QW into the nonmagnetic GaAs QW and vice versa. Magneto-photoluminescence studies demonstrate level anticrossing and strong intermixing resulting in a drastic renormalization of the electron effective g factor, in perfect agreement with the energy level calculations.Comment: 4 pages, 5 Postscript figures, uses revtex

Effects of a cooling vest with sham condition on walking capacity in heat-sensitive people with Multiple Sclerosis

Purpose: Heat sensitivity is a common contraindication in people with Multiple Sclerosis (pwMS), and physical fatigue is one of the most frequently reported symptoms that can affect quality of life. Increases in body temperature may exacerbate fatigue and heat-related symptoms. Decreasing body temperature via cooling devices may mitigate disease symptoms and improve physical abilities and quality of life. This study evaluates the effects of a cooling vest with sham condition on walking capacity using a commercially-available cooling vest specifically designed for pwMS. Methods: A counter-balanced, cross-over design was used to assess the effects of a cooling vest (CryoVest Comfort, CryoInnov, France) (COLD) from a menthol-induced sham condition (CON) on ground walking time to exhaustion (Tex, s) and distance at exhaustion (Dex, m) in ambulatory pwMS. Secondary outcomes were heart rate (HR, bpm), thermal sensation (Tsens), skin chest (Tchest) and back (Tback) temperature. Results: Ten females with Multiple Sclerosis (59 \ub1 9\ua0years, EDSS 3.0\u20135.5) participated to the study. During COLD, pwMS walked significantly longer (1896 \ub1 602 vs. 1399 \ub1 404\ua0s, p < 0.001) and farther (1879 \ub1 539 vs. 1302 \ub1 318\ua0m, p < 0.001) than CON. Importantly, Tsens and HR at exhaustion were not significantly different between conditions, although Tchest ( 12\ua02.7 \ub1 1.8\ua0\ub0C, p < 0.01) and Tback ( 12\ua03.9 \ub1 1.8\ua0\ub0C, p < 0.001) were lower at volitional fatigue during COLD. Conclusion: The lightweight cooling vest improved total walking time and distance in heat-sensitive pwMS. These physiological improvements were likely due to feeling perceptually cooler in the COLD trial, compared to the corresponding point of fatigue in the CON condition

Pediatric diabetes training for healthcare professionals in Europe: Time for change.

BACKGROUND: Training for healthcare professionals (HCPs) in Europe who care for children and young people (CYP) with type 1 diabetes and their families is variable depending on the country. Building on the work of SWEET (Better control in Pediatric and Adolescent diabeteS: Working to crEate CEnTers of Reference) and using the German Certified Diabetes Educators (CDEs) curriculum, a European collaboration of pediatric diabetes experts aimed to (1) establish current core elements that should be included in a pediatric diabetes education training course and (2) create a template for a European CDE's training curriculum. METHODS: A qualitative methodology incorporating a survey questionnaire, focus group discussions, individual semi-structured interviews and workshops was employed to explore participants' experiences and opinions. HCPs-pediatric consultants, diabetes nurses, dietitians and psychologists, national and local diabetes leads, academic and education leads and children, and young people with diabetes and families took part in the study. The total number of participants equaled 186. RESULTS: A template for a European Certified Diabetes Educator Curriculum (EU-CDEC) was developed based on the themes that emerged from the participants' expertise and experiences. This provides a model for HCPs' pediatric diabetes training provision. CONCLUSIONS: There is a severe shortage of high quality, standardized training for HCPs across the majority of European countries. Lack of trained HCPs for CYP with diabetes will result in the delivery of suboptimal care and impact on health, wellbeing and clinical and psychological outcomes. The EU-CDEC template can be used to increase access to high quality training provision for all HCPs across Europe and worldwide

Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission

The longitudinal development and other characteristics of the EECR induced atmospheric showers can be studied from space by detecting the fluorescence light induced in the atmospheric nitrogen. According to the Airwatch concept a single fast detector can be used for measuring both intensity and time development of the streak of fluorescence light produced by the atmospheric shower induced by an EECR. In the present communication the detection capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9

The influence of LiF layer abd ZnO nanoparticels addings on the performances of flexible photovoltaic cells based on polymer blends

International audienceFlexible organic solar cells were successfully prepared using spin-coating technique on PET substrates covered with a thick layer of ITO. The goal of this study is to identify the effects of the LiF layer and ZnO nanoparticles mixing in PEDOT:PSS solution and to compare the photovoltaic properties of these „customized” cells PET/ITO/PEDOT:PSS + ZnO nanoparticles/P3HT:PCBM(1:1)/Al, PET/ITO/PEDOT:PSS + ZnO nanoparticles/P3HT:PCBM(1:1)/LiF/Al, with ones of the “conventional” structures, PET/ITO/PEDOT:PSS/P3HT:PCBM(1:1)/Al. The thickness of the LiF layer, deposited by thermal vacuum evaporation, was two nanometers. Composite samples were prepared by adding ZnO nanoparticles into PEDOT:PSS solution, followed by ultrasonication. I-V characteristics were measured in dark and under A.M.1.5 conditions for all samples immediately and after one month from the preparation date. The action spectra measurements revealed that the structures which have a nanometric LiF layer are more stable than those without. Photoelectrical measurements indicate that the ZnO nanoparticles have a positive influence on the conversion efficiency and also to reduce the serial resistance of the structure

A longitudinal study of brain atrophy and cognitive disturbances in the early phase of relapsing-remitting multiple sclerosis

Objective—(a) To establish whether the cognitive decline of the early phase of relapsing-remitting multiple sclerosis depends on the progression of the burden of disease, or on the loss of brain parenchyma, or is influenced by both; (b) to monitor the loss of brain parenchyma in the early phase of the disease; and (c) to examine its possible relation with the progression of physical disability. Methods—For 2 years 53 patients with clinically definite relapsing-remitting multiple sclerosis with disease duration 1–5 years and expanded disability status scale<5.0 at baseline were monitored.The neuropsychological performances, the psychological functioning, the neurological impairment, and the disability have beenassessedatbaselineandafter2years. Patients also underwent PD/T2 and T1 weighted brain MRI.T2 and T1 lesion volumes were measured by a semiautomatic technique. Quantification of brain parenchymal volumes was obtained using a highly reproducible computerised interactive program. The relation between cognitive impairment and MRI findings has been investigated by partial correlation and stepwise multiple regression analyses excluding the eVects of age, education, anxiety, depression, and total days of steroid use. Results—In the 2 years of the study the meanchangeforT2andT1lesionvolumes and brain parenchymal volumes were +1.7 ml (95% confidence interval (95% CI) 1.3– 2.2, p=0.005, (29.8%); +0.2 ml, 95% CI 0.15–0.26, p=0.004, (25%); and –32.3 ml, 95% CI 24.2–42.3, p<0.0001, (2.7%), respectively. Overall, 14 patients (26.4%) were judged to be cognitively impaired at baseline and 28 (52.8%) at the end of the follow up. Of the 18 neuropsychological tests and subtests employed in the study, patients with multiple sclerosis failed 5.8 (SD 2.3) tests at the baseline and 8.4 (SD 2.9) (p<0.0001) tests at the end of the study. When the cognitive changes were examined in individual patients, five (9.4%) of them were considered cognitively improved, 33 (62.3%) remained stable, and 15 (28.3%) worsened over 2 years. T2 and T1 volume changes in improved, stable, and worsened patients did not show any significant diVerence, whereas brain parenchymal volume decrease in cognitively worsened patients was significantly greater (−66 ml (5.4%), 95% CI 37–108.9, p=0.0031). The cognitive impairment was independently predicted over 2 years only by the change of brain parenchymal volumes (R=0.51, p=0.0003). Ten patients (18.9%), who worsened by one or more points in the EDSS during the follow up period had significant decreases in brain parenchymal volumes (−99 ml (8%),95% CI 47.6–182.3,p=0.005). At the end of the study the loss of brain parenchyma correlated significantly with change in EDSS (r= 0.59, p<0.0001). Conclusions—In the early phase of relapsing-remitting multiple sclerosis the cognitive deterioration relies more on the development of brain parenchymal volume atrophy than on the extent of burden of disease in the brain. The loss of brain parenchymal volume underlies the progressive accumulation of physical disability from the initial phase of the disease, which becomes more demonstrable only if studied with longer observation periods. Probably, the main pathological substrate of brain atrophy in the early stage of the disease is early axonal loss, which causes the progression of neurological deficits and the development of cognitive impairment. These data support the debated opinion that disease modifying therapy should be initiated as early as possible