23 research outputs found

    Ruthenocuprates RuSr2(Eu,Ce)2Cu2O10: Intrinsic magnetic multilayers

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    We report ac susceptibility data on RuSr_2(Eu,Ce)_2Cu_2O_(10-y) (Ru-1222, Ce content x=0.5 and 1.0), RuSr_2GdCu_2O_8 (Ru-1212) and SrRuO_3. Both Ru-1222 (x=0.5, 1.0) sample types exhibit unexpected magnetic dynamics in low magnetic fields: logarithmic time relaxation, switching behavior, and `inverted' hysteresis loops. Neither Ru-1212 nor SrRuO_3 exhibit such magnetic dynamics. The results are interpreted as evidence of the complex magnetic order in Ru-1222. We propose a specific multilayer model to explain the data, and note that superconductivity in the ruthenocuprate is compatible with both the presence and absence of the magnetic dynamics.Comment: 9 pages, 11 figures, Revtex; submitted to Phys.Rev.

    Topological and geometrical restrictions, free-boundary problems and self-gravitating fluids

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    Let (P1) be certain elliptic free-boundary problem on a Riemannian manifold (M,g). In this paper we study the restrictions on the topology and geometry of the fibres (the level sets) of the solutions f to (P1). We give a technique based on certain remarkable property of the fibres (the analytic representation property) for going from the initial PDE to a global analytical characterization of the fibres (the equilibrium partition condition). We study this analytical characterization and obtain several topological and geometrical properties that the fibres of the solutions must possess, depending on the topology of M and the metric tensor g. We apply these results to the classical problem in physics of classifying the equilibrium shapes of both Newtonian and relativistic static self-gravitating fluids. We also suggest a relationship with the isometries of a Riemannian manifold.Comment: 36 pages. In this new version the analytic representation hypothesis is proved. Please address all correspondence to D. Peralta-Sala

    Short-range order effects in amorphous FexSi1-x/Si multilayers induced by preparation conditions

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    Magnetic properties of compositionally modulated FexSi1-x/Si amorphous multilayers are reported. The concentration x was 0.68 ≤ x ≤ 0.82 for two nominal modulation lengths λ of 4 and 8 Å. The samples were prepared by pulsating two-cathode sputtering. From SQUID magnetometry and transverse magneto-optic Kerr effect, we detected a noticeable decrease in both magnetization and relative reflectivity (δ=ΔR/R) as λ increases from 4 to 8 Å. Also, for a fixed value of x, it was found that both coercive field and in-plane uniaxial anisotropy constant decrease systematically for increasing λ. The two pulses used in the preparation method causes slight chemical short range effects, altering also the magnetic properties by changing the number and nature of nearest neighbors of a given Fe atom. The above short-range effects are present even when no multilayer structure is detected by x-ray diffraction

    Thermal evolution of magnetic properties of thin films having perpendicular anisotropy

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    In this work we report on the temperature evolution (10K-470K) of the magnetization processes of amorphous FexSi1-x thin films having perpendicular anisotropy. The film thickness was close to 100 nm. Hysteresis loops show the estinction of stripe domains at a critical temperature of Tc = 250K. In order to analyze possible changes in anisotropies (perpendicular and in-plane) throughout the film thickness, we compare bulk properties measured by Alternating Gradient Magnetometer (AGM) with results obtained from MOKE at both film interfaces

    Coupling of YCo2 thin films in a macroscopic ferrimagnet

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    We study here the behavior of YCo2 thin films when they are decoupled or when they are 3d-coupled in a macroscopic ferrimagnet (MF). The latter consists of YCo2/GdCo2/YCo2, the thickness of each layer (100 nm) being higher than the optical penetration depth. Such a study was done by means of the transverse magneto optic Kerr effect (TMOKE) hysteresis loops and their evolution upon applying a dc field perpendicularly to the easy axis of magnetization. We observe clear differences between magnetically decoupled layers and layers coupled in the MF. The latter case may be understood taken into account that the exchange interaction in the MF is controlled by the existence of a Bloch-type domain wall extending through the layered system

    Interventions to improve osteoporosis medication adherence and persistence: a systematic review and literature appraisal by the ISPOR Medication Adherence & Persistence Special Interest Group

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    This study aims to systematically review, critically appraise and identify from the published literature, the most effective interventions to improve medication adherence in osteoporosis. A literature search using Medline, EMBASE, Cochrane library, and Cumulative Index to Nursing and Allied Health Literature was undertaken to identify prospective studies published between January 1, 1999 and June 30, 2012. We included studies on adult users of osteoporosis medications that tested a patient adherence intervention (e.g., patient education, intensified patient care, different dosing regimens) and reported quantitative results of adherence. The Delphi list was modified to assess the quality of studies. Of 113 articles identified, 20 studies fulfilled the inclusion criteria. The most frequent intervention was education (n = 11) followed by monitoring/supervision (n = 4), drug regimens (n = 2), drug regimens and patient support (n = 1), pharmacist intervention (n = 1), and electronic prescription (n = 1). Although patient education improved medication adherence in four studies, two large-scale randomized studies reported no benefits. Simplification of dosing regimens (with and without patient support program) was found to have a significant clinical impact on medication adherence and persistence. Monitoring/supervision showed no impact on medication persistence while electronic prescription and pharmacist intervention increased medication adherence or persistence. In conclusion, this review found that simplification of dosing regimens, decision aids, electronic prescription, or patient education may help to improve adherence or persistence to osteoporosis medications. We identified wide variation of quality of studies in the osteoporosis area. The efficacy of patient education was variable across studies, while monitoring/supervision does not seem an effective way to enhance medication adherence or persistence

    Potencial biótico da mosca-branca Bemisia argentifolii a diferentes plantas hospedeiras Biotic potential of Bemisia argentifolii to different host plants

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    A mosca-branca Bemisia argentifolii Bellows & Perring, 1994 causa danos em diversas culturas de importância econ��mica no Brasil. Este trabalho teve o objetivo de avaliar o potencial biótico do inseto nas plantas de abobrinha, feijão, mandioca, milho, poinsétia, repolho e tomate. Os experimentos foram conduzidos na Embrapa Hortaliças, em Brasília-DF, em câmaras climatizadas, à temperatura de 28 &plusmn; 2&ordm;C e casa de vegetação, à temperatura ambiente (25 &plusmn; 8&ordm;C), partindo-se de uma população de B. argentifolii, criada em poinsétia desde 1995. Repolho e feijão foram as plantas hospedeiras que apresentaram períodos pré-imaginais mais curtos, respectivamente 20,5 e 21,9 dias. As maiores porcentagens de mortalidade nesses períodos foram observadas em mandioca (97,9%) e milho (94,2%). A razão sexual em geral foi favorável às fêmeas. O inseto apresentou valores muito próximos de r m (capacidade intrínseca de crescimento da população), variando de 0,18 em feijão a 0,13 em repolho, mostrando estar igualmente adaptado a estes hospedeiros. Resultados diversos foram observados em milho e mandioca, onde as fêmeas apresentaram alta mortalidade (> 90%), o que sugere baixa capacidade de utilização destes hospedeiros pela mosca-branca.<br>The whitefly Bemisia argentifolii Bellows & Perring, 1994 has been causing damage in several economically important crops in Brazil. The purpose of this research was to determine the biotic potential of the insect in zucchini, dry bean, cassava, corn, poinsettia, cabbage and tomato. The experiments were carried out at the Experimental Station of Embrapa Hortaliças, located in Brasilia, in BOD chamber (28&deg;C &plusmn; 2&deg;C) and greenhouse (25&deg;C &plusmn; 8&deg;C), with a whitefly population continuously reared on poinsettia plants since 1995. Cabbage and dry bean were the host plants with shorter pre-imaginal periods, 20.5 and 21.9 days respectively. The highest mortality in this periods was observed in cassava (97.9%) and corn (94.2%). Sexual ratio (female:male) favored females. The insect presented a small range for the intrinsic rate of increase (r m), 0.18 for dry bean and 0.13 for cabbage, reflecting the similar adaptability to both hosts. Lower intrinsic rates of increase were observed in corn and cassava, with high female mortality (> 90%), suggesting that these two species were less suitable hosts for this whitefly population

    Immunocompromised patients with acute respiratory distress syndrome : Secondary analysis of the LUNG SAFE database

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    The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p < 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p < 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013
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