138 research outputs found

    Helical edge states in multiple topological mass domains

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    The two-dimensional topological insulating phase has been experimentally discovered in HgTe quantum wells (QWs). The low-energy physics of two-dimensional topological insulators (TIs) is described by the Bernevig-Hughes-Zhang (BHZ) model, where the realization of a topological or a normal insulating phase depends on the Dirac mass being negative or positive, respectively. We solve the BHZ model for a mass domain configuration, analyzing the effects on the edge modes of a finite Dirac mass in the normal insulating region (soft-wall boundary condition). We show that at a boundary between a TI and a normal insulator (NI), the Dirac point of the edge states appearing at the interface strongly depends on the ratio between the Dirac masses in the two regions. We also consider the case of multiple boundaries such as NI/TI/NI, TI/NI/TI and NI/TI/NI/TI.Comment: 11 pages, 15 figure

    Helical edge states in multiple topological mass domains

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    The two-dimensional topological insulating phase has been experimentally discovered in HgTe quantum wells (QWs). The low-energy physics of two-dimensional topological insulators (TIs) is described by the Bernevig-Hughes-Zhang (BHZ) model, where the realization of a topological or a normal insulating phase depends on the Dirac mass being negative or positive, respectively. We solve the BHZ model for a mass domain configuration, analyzing the effects on the edge modes of a finite Dirac mass in the normal insulating region (soft-wall boundary condition). We show that at a boundary between a TI and a normal insulator (NI), the Dirac point of the edge states appearing at the interface strongly depends on the ratio between the Dirac masses in the two regions. We also consider the case of multiple boundaries such as NI/TI/NI, TI/NI/TI and NI/TI/NI/TI.Comment: 11 pages, 15 figure

    The beta Pictoris association: Catalog of photometric rotational periods of low-mass members and candidate members

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    We intended to compile the most complete catalog of bona fide members and candidate members of the beta Pictoris association, and to measure their rotation periods and basic properties from our own observations, public archives, and exploring the literature. We carried out a multi-observatories campaign to get our own photometric time series and collected all archived public photometric data time series for the stars in our catalog. Each time series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for the stellar rotation periods. We complemented the measured rotational properties with detailed information on multiplicity, membership, and projected rotational velocity available in the literature and discussed star by star. We measured the rotation periods of 112 out of 117 among bona fide members and candidate members of the beta Pictoris association and, whenever possible, we also measured the luminosity, radius, and inclination of the stellar rotation axis. This represents to date the largest catalog of rotation periods of any young loose stellar association. We provided an extensive catalog of rotation periods together with other relevant basic properties useful to explore a number of open issues, such as the causes of spread of rotation periods among coeval stars, evolution of angular momentum, and lithium-rotation connection.Comment: Forthcoming article, Received: 20 June 2016 / Accepted: 09 September 2016; 40 pages, 2 figures. The online figures A1-A73 are available at CD

    The rotation - Lithium depletion correlation in the beta Pictoris association and LDB age determination

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    There is evidence in the 125-Myr Pleiades cluster, and more recently in the 5-Myr NGC 2264 cluster, that rotation plays a key role in the Lithium (Li) depletion processes among low-mass stars. Fast rotators appear to be less Li-depleted than equal-mass slow rotators. We intend to explore the existence of a Li depletion - rotation connection among the beta Pictoris members at an age of about 24 Myr, and to use such correlation either to confirm or to improve the age estimate based on the Lithium Depletion Boundary (LDB) modeling. We have photometrically monitored all the known members of the beta Pictoris association with at least one Lithium equivalent width (Li EW) measurement from the literature. We measured the rotation periods of 30 members for the first time and retrieved from the literature the rotation periods for other 36 members, building a catalogue of 66 members with measured rotation period and Li EW. We find that in the 0.3 < M < 0.8 Msun range, there is a strong correlation between rotation and Li EW. For higher mass stars, no significant correlation is found. For very low mass stars in the Li depletion onset, at about 0.1 Msun, data are too few to infer a significant correlation. The observed Li EWs are compared with those predicted by the Dartmouth stellar evolutionary models that incorporate the effects of magnetic fields. After decorrelating the Li EW from the rotation period, we find that the hot side of the LDB is fitted well by Li EW values corresponding to an age of 25±3 Myr in good agreement with independent estimates from the literature.Fil: Messina, S.. Catania Astrophysical Observatory; ItaliaFil: Lanzafame, A. C.. Catania Astrophysical Observatory; ItaliaFil: Feiden, G. A.. Uppsala University; SueciaFil: Millward, M.. York Creek Observatory; AustraliaFil: Desidera, S.. Osservatorio Astronomico Di Padova; ItaliaFil: Buccino, Andrea Paola. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Curtis, I.. Minor Planet Center; AustraliaFil: Jofre, Jorge Emiliano. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kehusmaa, P.. Harlingten Atacama Observatory; ChileFil: Medhi, B. J.. Aryabhatta Research Institute Of Observational Sciences; IndiaFil: Monard, B.. Klein Karoo Observatory; SudáfricaFil: Petrucci, Romina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentin

    Understanding Technology as Situated Practice: Everyday use of Voice User Interfaces Among Diverse Groups of Users in Urban India

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    Abstract: As smartphones have become ubiquitous across urban India, voice user interfaces (VUIs) are increasingly becoming part of diverse groups of users’ daily experiences. These technologies are now generally accessible as a result of improvements in mobile Internet access, [-8.5pc]Biography is Required. Please provide. introduction of low-cost smartphones and the ongoing process of their localisation into Indian languages. However, when people engage with technologies in their everyday lives, they not only enact the material attributes of the artifact but also draw on their skills, social positions, prior experience and societal norms and expectations to make use of the artifact. Drawing on Orlikowski’s analytical framework of “technologies-in-practice” we engage in an interview-based exploratory study among diverse groups of users in urban India to understand use of VUIs as situated practice. We identify three technologies-in-practice emerging through enactment of VUIs on users’ smartphones: looking up, learning and leisure. We argue that – instead of asking why and how users appropriate VUIs – identifying different kinds of enactments of VUIs present researchers and practitioners with a more nuanced understanding of existing and potential use of VUIs across varied contexts

    The Correlation of Ig M Anti PGL-1 antibody between blood veins and dryed capillary blood on filter papers in household contact of leprosy patient

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    Delays of leprosy detection and treatment can lead to disability and potential transmission. Serologic examination has the advantage in detecting Subclinical Leprosy. The procedure of serologic test, which is one of its main limitation, could be simplified by the use filter paper. This study aims to assess the effectiveness of the use of capillary blood dropped on filter paper as a substitute for venous blood in household contact of leprosy patients. Seventeen samples of capillary blood dried on filter paper and venous blood samples from the same individual were examined by ELISA method to determine the levels of IgM anti-Phenolic glycolipid-1 (PGL-1). The mean of anti- PGL-1 IgM levels of filter paper samples 163.31±126.16; whereas the mean of levels from venous samples was 473.16±411.26. There was significant difference and correlation between these two groups. Samples on filter paper in household contact can be used to determine the level of anti-PGL-1 IgM in serum by converting on the regression basis. Further study is required to evaluate the potency of filter paper methods to conduct large-scale serological screening

    Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

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    Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)

    Efficacy and Safety of Artemether in the Treatment of Chronic Fascioliasis in Egypt: Exploratory Phase-2 Trials

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    Fasciola hepatica and F. gigantica are two liver flukes that parasitize herbivorous large size mammals (e.g., sheep and cattle), as well as humans. A single drug is available to treat infections with Fasciola flukes, namely, triclabendazole. Recently, laboratory studies and clinical trials in sheep and humans suffering from acute fascioliasis have shown that artesunate and artemether (drugs that are widely used against malaria) also show activity against fascioliasis. Hence, we were motivated to assess the efficacy and safety of oral artemether in patients with chronic Fasciola infections. The study was carried out in Egypt and artemether administered according to two different malaria treatment regimens. Cure rates observed with 6×80 mg and 3×200 mg artemether were 35% and 6%, respectively. In addition, high efficacy was observed when triclabendazole, the current drug of choice against human fascioliasis, was administered to patients remaining Fasciola positive following artemether treatment. Concluding, monotherapy with artemether does not represent an alternative to triclabendazole against fascioliasis, but its role in combination chemotherapy regimen remains to be investigated

    User preferences for adaptive user interfaces in health information systems

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    An adaptive user interface requires identification of user requirements. Interface designers and engineers must understand end-user interaction with the system to improve user interface design. A combination of interviews and observations is applied for user requirement analysis in health information systems (HIS). Then, user preferences are categorized in this paper as either data entry, language and vocabulary, information presentation, or help, warning and feedback. The user preferences in these categories were evaluated using the focus group method. Focus group sessions with different types of HIS users comprising medical staff (with and without computer skills) and system administrators identified each user group’s preference for the initial adaptation of the HIS user interface. User needs and requirements must be identified to adapt the interface to users during data entry into the system. System designers must understand user interactions with the system to identify their needs and preferences. Without this, interface design cannot be adapted to users and users will not be comfortable using the system and eventually abandon its use
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