540 research outputs found

    Growth of monolayer graphene on 8deg off-axis 4H-SiC (000-1) substrates with application to quantum transport devices

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    Using high temperature annealing conditions with a graphite cap covering the C-face of an 8deg off-axis 4H-SiC sample, large and homogeneous single epitaxial graphene layers have been grown. Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements. We find a moderate p-type doping, high carrier mobility and half integer Quantum Hall effect typical of high quality graphene samples. This opens the way to a fully compatible integration of graphene with SiC devices on the wafers that constitute the standard in today's SiC industry.Comment: 11 pages, 4 figures , Submitted in AP

    Optimisation de la fermentation en milieu semi-solide pour la production d’ablo, pain cuit a la vapeur d’Afrique de l’ouest

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    Objectif : Evaluer trois équipements pour la fermentation de la pâte destinée à préparer l’ablo (pâte cuite à la vapeur) puis, l’influence de la température, de la durée de fermentation et du taux de levure ajoutée à la pâte.Méthodologie et résultats : La pâte semi-solide a été fermentée durant quatre heures à température ambiante (26-27 °C) dans du bac en verre, glacière et bassine en aluminium (Témoin). En outre, l’effet de la température, de la durée de fermentation et du taux de levure a été évalué à travers un dispositif factoriel complet dont les niveaux bas et hauts des facteurs rangeaient entre 2 et 6 heures, 22 et 30 °C et 1 et 3 g/Kg de farine. La pousse, le pH, l’acidité titrable et la charge en levures/moisissures ont été déterminés. A l’exception de la quantité de mousse produite et de la matière sèche, aucun effet significatif (P>0,05) du matériel de fermentation n’a été mis en évidence sur les paramètres mesurés. Le taux de levure, la température et la durée de fermentation avaient une influence positive significative (P<0,05) sur la quantité de mousse produite.Conclusion et application : Le dispositif en verre, suivi de la glacière, avaient généré la plus grande quantité de mousse, probablement à cause d’une relative herméticité ou de la forme géométrique régulière des deux dispositifs. Au rendement en pâte voisin de 180, la fermentation dans les conditions optimales validées exigeait 30 °C, 3 g de levure par Kg de farine de riz et 4 h de conditionnement ; ce qui donne une pâte fermentée possédant un pH compris entre 4,42 et 4,64, une teneur de matière sèche variant entre 29,99 et 38,79% et la variation de hauteur de la mousse comprise entre 4,85 et 5,62 cm. Il serait intéressant de tester ces conditions optima de fermentation sur autres matières premières (maïs, mélange riz-maïs) intervenant dans la production d’ablo.Mots clés : Ablo, levures, optimisation, fermentation, rizOptimization of semi-solid state fermentation for processing ablo, a wet steamed bread from West AfricaObjective: To test three equipments for the fermentation of rice semi-solid dough to produce ablo (a steamy and foamy bread) and then, to investigate the effect of fermentation temperature and duration and the rate of yeast on some critical parametersMethodology and results: The semi-solid dough was fermented for four hours in glass box, icebox and aluminum bowls (Control) at ambient temperature (26-27 °C). In addition, the effect of fermentation temperature and duration and the rate of yeast were investigated using full factorial design, with values ranging between 2 and 6 hours, 22 and 30 °C and 1 and 3 g/Kg flour. The pH, titrable acidity, the dry matter content and the quantity of moss/foam were determined as well as the yeast and fungi counts. Except for the moss produced and the dry matter content, no significant effect was evidenced on all other parameters measured as far as the equipment is considered. Significant and positive effects of temperature, duration and the rate of yeast (P<0.05) were observed on the quantity of moss producedConclusion and application: The glass box, followed by icebox were the best fermenting equipments of the dough, giving great amount of moss produced, probably due the airtight or the regular form of both equipments. At the dough yield of 180, the optimal values of these factors for upgrading fermentation of the rice dough included 30 °C, 3 g of yeast per Kg of flour and 4 hours of resting. These conditions was validated and lead to the fermented dough with pH ranging between 4.42 and 4.64, dry matter between 29.99 et 38.79% and moss height varying from 4.85 to 5.62 cm. In further work, it will be appreciated to test these optima conditions on maize or the mix rice-maize flour since they are raw materials for ablo productionKeywords: Yeast, optimization, fermentation, Abl

    Self-consistency in Theories with a Minimal Length

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    The aim of this paper is to clarify the relation between three different approaches of theories with a minimal length scale: A modification of the Lorentz-group in the 'Deformed Special Relativity', theories with a 'Generalized Uncertainty Principle' and those with 'Modified Dispersion Relations'. It is shown that the first two are equivalent, how they can be translated into each other, and how the third can be obtained from them. An adequate theory with a minimal length scale requires all three features to be present.Comment: typos corrected, published with new title following referee's advic

    CONNECTIVITY BETWEEN POPULATIONS OF THE MARINE CRAB LIOCARCINUS DEPURATOR IN THE ATLANTO-MEDITERRANEAN TRANSITION: A FIVE YEAR SERIES

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    Abstract: We carried out a spatial and temporal genetic differentiation analysis using seven populations of the marine crab Liocarcinus depurator to elucidate the effect of three oceanographic discontinuities in the Atlanto-Mediterranean coast: Gibraltar Strait, Almeria-Oran Front and Ibiza Channel. To conduct this study, a 527 bp fragment of the mitochondrial COI gene was sequenced in individuals captured in the period 2014-2018 from the following Iberian coast populations: Cádiz, West Alboran, East Alboran, Alacant, Valencia, Ebro Delta and North Catalonia. Two haplogroups were detected; one characteristic of Atlantic waters and the other of Mediterranean. Their differential distribution allowed understanding the connectivity between populations. The effect of the oceanographic fronts on gene flow varied over time. Their effects were significant for the Gibraltar Strait (2014 and 2017), Almeria Oran Front (2013, 2014, 2015, 2016 and 2017) and Ibiza Channel (2015). Interestingly, the joint analysis of West Alboran, East Alboran and Alacant populations allowed a more precise detection of the location of the Almeria Oran Front biological effects. Finally, significant differences were observed in connectivity between Valencia and Ebro Delta in 2015, although there is not an oceanographic discontinuity between them. The main conclusion is that the gene flow is mediated by oceanographic fronts, but their intensity and effects change over time.CTM2017-88080 AEI/FEDER, UE) (CTM2015-66400-C3-3-R MINECO/FEDER) (2017 SGR 1120)

    Nuclear recoil measurements in Superheated Superconducting Granule detectors

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    The response of Superheated Superconducting Granule (SSG) devices to nuclear recoils has been explored by irradiating SSG detectors with a 70Me ⁣\!V neutron beam. In the past we have tested Al SSG and more recently, measurements have been performed with Sn and Zn detectors. The aim of the experiments was to test the sensitivity of SSG detectors to recoil energies down to a few ke ⁣\!V. In this paper, the preliminary results of the neutron irradiation of a SSG detector made of Sn granules 15-20μ\mum in diameter will be discussed. For the first time, recoil energy thresholds of \sim1ke ⁣\!V have been measured.Comment: 7pages in Latex format, Preprint Bu-He 93/6 (University of Berne, Switzerland), four figures available upon request via [email protected] or [email protected]

    Medication-related hospital admissions and readmissions in older patients: an overview of literature

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    Background The number of medication related hospital admissions and readmissions are increasing over the years due to the ageing population. Medication related hospital admissions and readmissions lead to decreased quality of life and high healthcare costs. Aim of the review To assess what is currently known about medication related hospital admissions, medication related hospital readmissions, their risk factors, and possible interventions which reduce medication related hospital readmissions. Method We searched PubMed for articles about the topic medication related hospital admissions and readmissions. Overall 54 studies were selected for the overview of literature. Results Between the different selected studies there was much heterogeneity in definitions for medication related admission and readmissions, in study population and the way studies were performed. Multiple risk factors are found in the studies for example: polypharmacy, comorbidities, therapy non adherence, cognitive impairment, depending living situation, high risk medications and higher age. Different interventions are studied to reduce the number of medication related readmission, some of these interventions may reduce the readmissions like the participation of a pharmacist, education programmes and transition-of-care interventions and the use of digital assistance in the form of Clinical Decision Support Systems. However the methods and the results of these interventions show heterogeneity in the different researches. Conclusion There is much heterogeneity in incidence and definitions for both medication related hospital admissions and readmissions. Some risk factors are known for medication related admissions and readmissions such as polypharmacy, older age and additional diseases. Known interventions that could possibly lead to a decrease in medication related hospital readmissions are spare being the involvement of a pharmacist, education programs and transition-care interventions the most mentioned ones although controversial results have been reported. More research is needed to gather more information on this topic

    Nanoscale magnetic structure and properties of solution-derived self-assembled La0.7Sr0.3MnO3 islands

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    The following article appeared in Journal of Applied Physics 111.2 (2012): 024307 and may be found at http://scitation.aip.org/content/aip/journal/jap/111/2/10.1063/1.3677985Strain-induced self-assembled La0.7Sr0.3MnO 3 nanoislands of lateral size 50-150 nm and height 10-40 nm have been grown on yttria-stabilized zirconia (001)-substrates from ultradiluted chemical solutions based on metal propionates. The nanoislands grow highly relaxed withstanding the epitaxial relation (001)LSMO[110]//(001) Ysz[010] and show bulk-like average magnetic properties in terms of Curie temperature and saturation magnetization. The interplay of the magnetocrystalline and shape anisotropy within the nanoisland ensemble results in an in-plane magnetic anisotropy with a magnetocrystalline constant K 1(150K) = -(5±1) kJ/m3 and in-plane easy axis along the [110] -La0.7Sr0.3MnO3 direction as measured, for the first time, through ferromagnetic resonance experiments. Magnetic force microscopy studies reveal the correlation between nanoisland size and its magnetic domain structure in agreement with micromagnetic simulations. In particular, we have established the required geometric conditions for single domain, multidomain, and vortex configurations.We acknowledge the financial support from MEC (MAT2008-01022, Consolider NANOSELECT and FPU), Comunidad Autónoma de Madrid (CAM S2009/MAT-1467), Generalitat de Catalunya (Catalan Pla de Recerca 2009-SGR- 770 and XaRMAE), and EU (NESPA). R. D. Zysler and C. A. Ramos acknowledge support from PIP-1333(2007) CONICET and PICT 829 (2006) and PICT 832(2006) ANPCyT of Argentina. Serveis Científic-Tècnics from Universitat de Barcelona and Servei de Micròscopia from Universitat Auto`noma de Barcelona are acknowledged for TEM facilities

    Infection control and the prevalence, management and outcomes of SARS-CoV-2 infections in mental health wards in London, UK: lessons learned from wave 1 to wave 2.

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    BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) has high morbidity and mortality in older adults and people with dementia. Infection control and prevention measures potentially reduce transmission within hospitals. AIMS: We aimed to replicate our earlier study of London mental health in-patients to examine changes in clinical guidance and practice and associated COVID-19 prevalence and outcomes between COVID-19 waves 1 and 2 (1 March to 30 April 2020 and 14 December 2020 to 15 February 2021). METHOD: We collected the 2 month period prevalence of wave 2 of COVID-19 in older (≥65 years) in-patients and those with dementia, as well as patients' characteristics, management and outcomes, including vaccinations. We compared these results with those of our wave 1 study. RESULTS: Sites reported that routine testing and personal protective equipment were available, and routine patient isolation on admission occurred throughout wave 2. COVID-19 infection occurred in 91/358 (25%; 95% CI 21-30%) v. 131/344, (38%; 95% CI 33-43%) P < 0.001 in wave 1. Hospitals identified more asymptomatic carriers (26/91; 29% v. 16/130; 12%) and fewer deaths (12/91; 13% v. 19/131; 15%; odds ratio = 0.92; 0.37-1.81) compared with wave 1. The patient vaccination uptake rate was 49/58 (85%). CONCLUSIONS: Patients in psychiatric in-patient settings, mostly admitted without known SARS-CoV-2 infection, had a high risk of infection compared with people in the community but lower than that during wave 1. Availability of infection control measures in line with a policy of parity of esteem between mental and physical health appears to have lowered within-hospital COVID-19 infections and deaths. Cautious management of vulnerable patient groups including mental health patients may reduce the future impact of COVID-19
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