956 research outputs found

    The Hubble Diagram of the Calan/Tololo Type Ia Supernovae and the value of Ho

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    The Calan/Tololo supernova survey has discovered ~30 Type Ia supernovae out to z~0.1. Using BVI data for these objects and nearby SNe Ia, we have shown that there exists a significant dispersion in the intrinsic luminosities of these objects. We have devised a robust chisquare minimization technique simultaneously fitting the BVI light curves to parametrize the SN event as a function of (tb,m, m15(B)) where tb is the time of B maximum, m is the peak BVI magnitude corrected for luminosity variations, and m15(B) is a single parameter describing the whole light curve morphology. When properly corrected for m15(B), SNe Ia prove to be high precision distance indicators,yielding relative distances with errors 7-10%. The corrected peak magnitudes are used to construct BVI Hubble diagrams (HD), and with Cepheid distances recently measured with the HST to four nearby SNe Ia (37C, 72E, 81B, 90N) we derive a value of the Hubble constant of 63.1+/-3.4 (internal) km/s/Mpc. This value is ~10-15% larger than the value obtained by assuming that SNe Ia are perfect standard candles. As we have shown in Paper V, there is now strong evidence that galaxies with younger stellar population appear to host the slowest-declining, and therefore most luminous SNe Ia. Hence, the use of Pop I objects such as Cepheids to calibrate the zero point of the SNe Ia HD can easily bias the results toward luminous SNe Ia, unless the absolute magnitude-decline relation is taken into account.Comment: 32 pages, figures attached, all tables available, to appear in the Astronomical Journa

    The Absolute Luminosities of the Calan/Tololo Type Ia Supernovae

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    We examine the absolute luminosities of 29 SNe Ia in the Calan/Tololo survey. We confirm a relation between the peak luminosity of the SNe and the decline rate as measured by the light curve, as suggested by Phillips (1993). We derive linear slopes to this magnitude-decline rate relation in BV(I)kc colors, using a sample with Bmax-Vmax < 0.2 mag. The scatter around this linear relation (and thus the ability to measure SNe Ia distances) ranges from 0.13 mag (in the I band) to 0.17 mag (in the B band). We also find evidence for significant correlations between the absolute magnitudes or the decline rate of the light curve, and the morphological type of the host galaxy.Comment: 21 pages, 4 figures, to appear in the Astronomical Journa

    Pure spin current manipulation in antiferromagnetically exchange coupled heterostructures

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    We present a model to describe the spin currents generated by ferromagnet/spacer/ferromagnet exchange coupled trilayer systems and heavy metal layers with strong spin-orbit coupling. By exploiting the magnitude of the exchange coupling (oscillatory RKKY-like coupling) and the spin-flop transition in the magnetization process, it has been possible to produce spin currents polarized in arbitrary directions. The spin-flop transition of the trilayer system originates pure spin currents whose polarization vector depends on the exchange field and the magnetization equilibrium angles. We also discuss a protocol to control the polarization sign of the pure spin current injected into the metallic layer by changing the initial conditions of magnetization of the ferromagnetic layers previously to the spin pumping and inverse spin Hall effect experiments. The small differences in the ferromagnetic layers lead to a change in the magnetization vector rotation that permits the control of the sign of the induced voltage components due to the inverse spin Hall effect. Our results can lead to important advances in hybrid spintronic devices with new functionalities, particularly, the ability to control microscopic parameters such as the polarization direction and the sign of the pure spin current through the variation of macroscopic parameters, such as the external magnetic field or the thickness of the spacer in antiferromagnetic exchange coupled systems.Fil: Avilés Félix, L.. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Butera, Alejandro Ricardo. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: González Chávez, D. E.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Sommer, R. L.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Gomez, Javier Enrique. Comision Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Bariloche). División Resonancias Magnéticas; Argentin

    The Morphology of Type Ia Supernovae Light Curves

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    We present a family of six BVI template light curves for SNe Ia for days -5 and +80, based on high-quality data gathered at CTIO. These templates display a wide range of light curve morphologies, with initial decline rates of their B light curves between m15(B)=0.87 mag and 1.93 mag. We use these templates to study the general morphology of SNe Ia light curves. We find that several of the main features of the BVI templates correlate tightly with m15(B). In particular, the V light curves, which are probably a reasonably good approximation of the bolometric light curves, display an orderly progression in shapes between the most-luminous, slowest-declining events and the least-luminous, fastest-declining SNe. This supports the idea that the observed spectroscopic and photometric sequences of SNe Ia are due primarily to one parameter. Nevertheless, SNe with very similar initial decline rates do show significant differences in their light curve properties when examined in detail, suggesting the influence of one or more secondary parameters.Comment: 32 pages, 15 figures, to appear in the Astronomical Journa

    Museum libraries in Spain: A case study at state level

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    Special libraries are essential information and documentation centres for university teachers and researchers due to the quality and richness of their collections. In Spain, it is estimated that there are 2456 special libraries, although many are unknown either generally or among information professionals. These include museum libraries, which are important centres with valuable collections of bibliographic heritage for the area of Humanities and Social Sciences. The aim of this research is to gain an understanding of the real state of these information units and promote the social value of museum libraries in Spain. To do this, a survey was sent to the libraries of state-owned and -managed museums under the General Directorate of Fine Arts and Cultural Property (Ministry of Culture and Sports) of the Government of Spain. This general objective will be accompanied by a review of the scientific literature on various aspects of museum libraries at national and international level. After addressing the research methodology, the results obtained will be discussed and will include the following topics: collection management, library services and staff, economic and technological resources and finally, library management. Conclusions include recommendations for museum librarians and reveal that institutional cooperation is a strategic issue to improve both museum libraries visibility and their social recognition as cultural and research centre

    Donar, un cambio de vida: comprender la experiencia de familiares que aceptaron la donación de órganos

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    Indexación: Web of Science; Scielo.Background: Most organ donors are already death. Therefore family members become an essential link in the final decision for organ donation. Aim: To get acquainted about the life lessons of people who accepted donating an organ of a deceased family member. Material and Methods: Qualitative research, in depth interviews to eight families that accepted donating an organ of a deceased family member. The interviews were analyzed using the method proposed by Streubert et al and modified by Rivera. Results: The life lessons are described in six comprehensive categories. The painful experience changed towards the feeling that the loved one remains alive. This sensation generated a sense of pride in family members and sensitized them towards the painful experience of other people. Therefore, a desire to help and improve as humans beings was awakened. Conclusions: A compassionate approach towards families donating organs with improve organ donation and humanize the process. Key words: Family; Social values; Tissue and organ procurement

    Ramon (\u3ci\u3eBrosimun alicastrum\u3c/i\u3e) Foliage as Supplement for Lactating Dual Purpose Cows

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    The objective of the present study was to asses the value of ramón (Brosimun alicastrum) foliage as a N-source in replacement of soybean-N in lactating dual purpose cows (Bos indicus x B. taurus). Four lactating cows were used in a latin rectangle design. Ramón was included to replace 0, 33, 66 and 100 % of the soybean-N contained in the supplement. Basal diet was fresh “Taiwán” a cultivar of Elephant grass (Pennisetum purpureum) fed ad libitum. Basal and total dry matter intake, digestibility (total fecal collection), saleable and calf suckled milk yields, and milk composition (fat, protein and lactose) were measured over 15 d periods. Ramon increased the yield of milk constituents (P\u3c 0.05) over those obtained with Taiwán-grass alone, but was inferior (P\u3c 0.05) when soybean was the N source. Total milk yield was reduced 18% in Ramón supplemented cows compared with those supplemented with soybean. Digestibility of dry matter, organic matter and fiber was reduced by Ramón inclusion probably due to its higher fiber and ash content as compared with soybean meal. It was concluded that, although animal performance was not achieved as with soybean meal, supplementing with Ramón is a better strategy than relying on grass alone

    Anisotropic Strain Induced Soliton Movement Changes Stacking Order and Bandstructure of Graphene Multilayers

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    The crystal structure of solid-state matter greatly affects its electronic properties. For example in multilayer graphene, precise knowledge of the lateral layer arrangement is crucial, since the most stable configurations, Bernal and rhombohedral stacking, exhibit very different electronic properties. Nevertheless, both stacking orders can coexist within one flake, separated by a strain soliton that can host topologically protected states. Clearly, accessing the transport properties of the two stackings and the soliton is of high interest. However, the stacking orders can transform into one another and therefore, the seemingly trivial question how reliable electrical contact can be made to either stacking order can a priori not be answered easily. Here, we show that manufacturing metal contacts to multilayer graphene can move solitons by several μ\mum, unidirectionally enlarging Bernal domains due to arising mechanical strain. Furthermore, we also find that during dry transfer of multilayer graphene onto hexagonal Boron Nitride, such a transformation can happen. Using density functional theory modeling, we corroborate that anisotropic deformations of the multilayer graphene lattice decrease the rhombohedral stacking stability. Finally, we have devised systematics to avoid soliton movement, and how to reliably realize contacts to both stacking configurations

    Beliefs, attitudes, death anxiety in a multidisciplinary team oncology palliative care

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    En el ámbito de la salud, se ha puesto en evidencia la necesidad de profundizar en las actitudes y creencias ante la muerte en los propios profesionales ya que pueden influir en la calidad de los cuidados, especialmente las derivadas de procesos de muerte y duelo, por lo que el objetivo de la investigación fue explorar y analizar actitudes y creencias ante la muerte en el personal de salud en Cuidados Paliativos Oncológicos. Fue un estudio, transversal y descriptivo; se utilizó un muestreo intencional, los instrumentos utilizados fueron: Formato de datos personales y profesionales, Escala de Ansiedad ante la muerte de Templer, Creencias con relación al paciente terminal y Cuestionario de Actitudes ante la Muerte (CAM). Se analizaron los datos estadísticamente: análisis de frecuencias y correlación de Spearman, con una alta tendencia en considerar que es mejor que el paciente terminal fallezca en casa, en el uso de la morfina como tratamiento para el dolor en cáncer avanzado y recibir una atención integral. Dentro de las principales actitudes del personal de salud hacia el paciente terminal y la muerte se encontraron: mayor responsabilidad y atención hacia la vida, y promoción del crecimiento personal para aceptar su propia muerte.In the field of health, has highlighted the need to delve into the attitudes and beliefs about death in the professionals because they can influence the quality of care, especially those derived from processes of death and mourning, for what the objective of the research was to explore and analyze attitudes and beliefs about death in health personnel Oncology Palliative Care. The study was a cross-sectional and descriptive, purposive sampling was used, the instruments used were format personal and professional, Anxiety Scale Templer’s death, beliefs regarding the terminal patient and Attitudes Questionnaire Death (CAM ). Data were analyzed statistically: Frequency analysis and Spearman correlation, with a high tendency to consider that is better than the terminal patient dies at home, in the use of morphine as a treatment for pain in advanced cancer and receiving comprehensive care. Among the main attitudes in the health staff towards the patient and death were found: more responsibility and attention to the promotion of life and personal growth to take his own life
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