1,211 research outputs found

    Landau-fluid simulations of Alfvén-wave instabilities in a warm collisionless plasma

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    A dispersive Landau-fluid model is used to study the decay and modulational instabilities of circularly-polarized Alfvén waves in a collisionless plasma, as well as their nonlinear developments. Comparisons are presented with the drift-kinetic approximation for the dispersionless regime and with hybrid simulations in more general conditions. The effect of the nature of the instability on particle heating is discussed, together with the formation of coherent structures or the development of an inverse cascade

    The momentum and photon energy dependence of the circular dichroic photoemission in the bulk Rashba semiconductors BiTeX (X = I, Br, Cl)

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    Bulk Rashba systems BiTeX (X = I, Br, Cl) are emerging as important candidates for developing spintronics devices, because of the coexistence of spin-split bulk and surface states, along with the ambipolar character of the surface charge carriers. The need of studying the spin texture of strongly spin-orbit coupled materials has recently promoted circular dichroic Angular Resolved Photoelectron Spectroscopy (cd-ARPES) as an indirect tool to measure the spin and the angular degrees of freedom. Here we report a detailed photon energy dependent study of the cd-ARPES spectra in BiTeX (X = I, Br and Cl). Our work reveals a large variation of the magnitude and sign of the dichroism. Interestingly, we find that the dichroic signal modulates differently for the three compounds and for the different spin-split states. These findings show a momentum and photon energy dependence for the cd-ARPES signals in the bulk Rashba semiconductor BiTeX (X = I, Br, Cl). Finally, the outcome of our experiment indicates the important relation between the modulation of the dichroism and the phase differences between the wave-functions involved in the photoemission process. This phase difference can be due to initial or final state effects. In the former case the phase difference results in possible interference effects among the photo-electrons emitted from different atomic layers and characterized by entangled spin-orbital polarized bands. In the latter case the phase difference results from the relative phases of the expansion of the final state in different outgoing partial waves.Comment: 6 pages, 4 figure

    Giant ambipolar Rashba effect in a semiconductor: BiTeI

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    We observe a giant spin-orbit splitting in bulk and surface states of the non-centrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics -- a large, robust spin splitting and ambipolar conduction -- are present in this material.Comment: 4 pages, 3 figure

    Conceptualising production, productivity and technology in pharmacy practice: a novel framework for policy, education and research.

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    CONTEXT AND BACKGROUND: People and health systems worldwide face serious challenges due to shifting disease demographics, rising population demands and weaknesses in healthcare provision, including capacity shortages and lack of impact of healthcare services. These multiple challenges, linked with the global push to achieve universal health coverage, have made apparent the importance of investing in workforce development to improve population health and economic well-being. In relation to medicines, health systems face challenges in terms of access to needed medicines, optimising medicines use and reducing risk. In 2017, the International Pharmaceutical Federation (FIP) published global policy on workforce development ('the Nanjing Statements') that describe an envisioned future for professional education and training. The documents make clear that expanding the pharmacy workforce benefits patients, and continually improving education and training produces better clinical outcomes. AIMS AND PURPOSE: The opportunities for harnessing new technologies in pharmacy practice have been relatively ignored. This paper presents a conceptual framework for analysing production methods, productivity and technology in pharmacy practice that differentiates between dispensing and pharmaceutical care services. We outline a framework that may be employed to study the relationship between pharmacy practice and productivity, shaped by educational and technological inputs. METHOD AND RESULTS: The analysis is performed from the point of view of health systems economics. In relation to pharmaceutical care (patient-oriented practice), pharmacists are service providers; however, their primary purpose is not to deliver consultations, but to maximise the quantum of health gain they secure. Our analysis demonstrates that 'technology shock' is clearly beneficial compared with orthodox notions of productivity or incremental gain implementations. Additionally, the whole process of providing professional services using 'pharmaceutical care technologies' is governed by local institutional frames, suggesting that activities may be structured differently in different places and countries. DISCUSSION AND CONCLUSION: Addressing problems with medication use with the development of a pharmaceutical workforce that is sufficient in quantity and competence is a long-term issue. As a result of this analysis, there emerges a challenge about the profession's relationship with existing and emerging technical innovations. Our novel framework is designed to facilitate policy, education and research by providing an analytical approach to service delivery. By using this approach, the profession could develop examples of good practice in both developed and developing countries worldwide

    Interest in and use of person-centred pharmacy services - a Swiss study of people with diabetes

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    BACKGROUND: Diabetes is one of the most important chronic diseases and affects 9% of the world's population. To support these people in the day-to-day management of their treatments, pharmacies can offer professional pharmacy services. These are defined as one or more actions organized or provided in a pharmacy to optimize the process of care, with the goal of improving health outcomes and the value of healthcare. Such services have to be tailored to the needs and interests of patients. This study aimed to evaluate interest in and use of pharmacy services among people with diabetes in the canton of Vaud, Switzerland. METHODS: This cross-sectional study analysed self-reported data from 790 people with diabetes included in the CoDiab-VD cohort. Questions focused on sociodemographic and economic characteristics, diabetes and its management, and interest in and use of pharmacy services related to (1) medication intake and adherence and (2) diabetes and general health. Descriptive analyses were first conducted. Logistic regression analyses were then performed for pharmacy services that were of interest to ≥50% of respondents. RESULTS: The mean age of participants was 66 years, and the sample included more males (59%) than females. The pharmacy services that interested the most respondents were individual interview, pill boxes or weekly pill boxes, treatment plans, checks of all medications, first medical opinions from pharmacists and counselling on devices. Factors significantly associated with interest in pharmacy services were being older, having a lower self-efficacy score, taking more than three medications and having a positive opinion about pharmacists. CONCLUSIONS: This study provides key information on interest in and use of pharmacy services among patients with diabetes in Switzerland; it should help pharmacists individualize their services for patients

    Impact of a Community Pharmacist-Delivered Information Program on the Follow-up of Type-2 Diabetic Patients: A Cluster Randomized Controlled Study.

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    Low-quality communication between patients and care providers and limited patient knowledge of the disease and the therapy are important factors associated with poor glycemic control in patients with type 2 diabetes. We conducted a multicenter study to determine whether structured and tailored information delivered by pharmacists to type 2 diabetic patients could improve patient treatment adherence, hemoglobin A1c (HbA1c) levels and knowledge about diabetes. One hundred seventy-four pharmacies were randomized to deliver an educational program on diet, drug treatment, disease and complications during three 30-min interviews over a 6-month period, or to provide no intervention, to type 2 diabetic patients treated with oral antidiabetic agents. Medication adherence was assessed by measuring the medication possession ratio and diabetes control by collecting HbA1c values. Levels of patient treatment self-management and disease knowledge were assessed using self-questionnaires. Three hundred seventy-seven patients were analyzed. The medication possession ratio, already very high at baseline in the intervention (94.8%) and control (92.3%) groups, did not vary significantly after 6 months with no difference between the two groups. Significant decreases in HbA1c were observed in both groups at 6 months (p < 0.001) and 12 months (p < 0.01), with significantly greater changes from baseline in the intervention group than in the control group at 6 months (- 0.5% vs. - 0.2%, p = 0.0047) and 12 months (- 0.6% vs. - 0.2%, p = 0.0057). Patients in the intervention group showed greater improvement in their ability to self-manage treatment (+ 4.86 vs. + 1.58, p = 0.0014) and in the extent of their knowledge about diabetes (+ 0.6 vs. + 0.2, p < 0.01) at 6 months versus baseline compared with the control group. Tailored information provided by the pharmacist to patients with type 2 diabetes did not significantly improve the already high adherence rates, but was associated with a significant decrease in HbA1c and an improvement of patient knowledge about diabetes. ISRCTN33776525. MSD France

    Control of CVD-deposited ZnO films properties through water/DEZ ratio: Decoupling of electrode morphology and electrical characteristics

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    In thiswork,itisshownthatvariationsintheratioofoxygentozincprecursorsatconstant temperatureallowchangingthesurfacemorphologyofzincoxide(ZnO)filmsdepositedbylow- pressuremetalorganicchemicalvapordeposition,whilekeepingthesheetresistanceandtransparency of thelayersconstant.ThisallowsdevelopingZnOlayerscombininginterestingpropertiessuchaslow surface roughness(below15nm)andlowsheetresistance(below15 O/&). Moregenerally,itisshown that thepyramidalfeaturedensitycanbecontrolledbytuningtheprecursorflows.Thisleadstofilm surfacescharacterizedbyzoneswitharoughmorphologymixedwithzoneswithalmostflatfeatures. Therefore,byusingthistechnique,thelight-scatteringabilityofafilmcanbecarefullytunedthrough its surfacemorphologywithoutaffectingtheconductivityortransparencyofthelayer.Thisprovidesan efficienttooltooptimizethefrontelectrodeofthin-filmsiliconsolarcellstoachievethebestpossible combinationofopen-circuitvoltage,fillfactorandphoto-generatedcurrent.Thepresentedsolutionis an in-situprocessachievableinstandarddepositionconditionsmakingiteasilyup-scalablewith existingproductionequipment

    Light-induced renormalization of the band structure of chiral tellurium

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    Chirality in tellurium arises from a Peierls distortion driven by strong electron-phonon coupling, making this material a unique candidate for observing a light-induced topological phase transition. Using time- and angle-resolved photoelectron spectroscopy (trARPES), we reveal that, upon near-infrared photoexcitation, the Peierls gap is modulated by displacively excited coherent phonons with A1g symmetry as well as chiral-symmetry-breaking ELO′ modes. By comparison with state-of-the-art TDDFT+U calculations, we reveal the microscopic origin of the in-phase oscillations of band edges, owing to phonon-induced modulation of the effective Hubbard U term

    Radial Spin Texture of the Weyl Fermions in Chiral Tellurium

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    Trigonal tellurium, a small-gap semiconductor with pronounced magneto-electric and magneto-optical responses, is among the simplest realizations of a chiral crystal. We have studied by spin- and angle-resolved photoelectron spectroscopy its unconventional electronic structure and unique spin texture. We identify Kramers–Weyl, composite, and accordionlike Weyl fermions, so far only predicted by theory, and show that the spin polarization is parallel to the wave vector along the lines in k space connecting high-symmetry points. Our results clarify the symmetries that enforce such spin texture in a chiral crystal, thus bringing new insight in the formation of a spin vectorial field more complex than the previously proposed hedgehog configuration. Our findings thus pave the way to a classification scheme for these exotic spin textures and their search in chiral crystals
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