265 research outputs found
Thermodynamic conditions during growth determine the magnetic anisotropy in epitaxial thin-films of LaSrMnO
The suitability of a particular material for use in magnetic devices is
determined by the process of magnetization reversal/relaxation, which in turn
depends on the magnetic anisotropy. Therefore, designing new ways to control
magnetic anisotropy in technologically important materials is highly desirable.
Here we show that magnetic anisotropy of epitaxial thin-films of half-metallic
ferromagnet LaSrMnO (LSMO) is determined by the proximity
to thermodynamic equilibrium conditions during growth. We performed a series of
X-ray diffraction and ferromagnetic resonance (FMR) experiments in two
different sets of samples: the first corresponds to LSMO thin-films deposited
under tensile strain on (001) SrTiO by Pulsed Laser Deposition (PLD; far
from thermodynamic equilibrium); the second were deposited by a slow Chemical
Solution Deposition (CSD) method, under quasi-equilibrium conditions. Thin
films prepared by PLD show a in-plane cubic anisotropy with an overimposed
uniaxial term. A large anisotropy constant perpendicular to the film plane was
also observed in these films. However, the uniaxial anisotropy is completely
suppressed in the CSD films. The out of plane anisotropy is also reduced,
resulting in a much stronger in plane cubic anisotropy in the chemically
synthesized films. This change is due to a different rotation pattern of
MnO octahedra to accomodate epitaxial strain, which depends not only on
the amount of tensile stress imposed by the STO substrate, but also on the
growth conditions. Our results demonstrate that the nature and magnitude of the
magnetic anisotropy in LSMO can be tuned by the thermodynamic parameters during
thin-film deposition.Comment: 6 pages, 8 Figure
Water transfer and crack regimes in nano-colloidal gels
International audienceDirect observations of the surface and shape of model nano-colloidal gels associated with measurements of the spatial distribution of water content during drying show that air starts to significantly penetrate the sample when the material stops shrinking. We show that whether the material fractures or not during desiccation, as air penetrates the porous body, the water saturation decreases but remains almost homogeneous throughout the sample. This air-invasion is at the origin of another type of fracture due to capillary effects; these results provide a new insight in the liquid dynamics at the nano-scale. PACS number(s): 47.56.+r, 68.03.Fg, 81.40.N
Increasing arterial blood pressure with norepinephrine does not improve microcirculatory blood flow: a prospective study
Innovación pedagógica para las clases de laboratorio de fÃsica
The pedagogical innovation here presented has the following objectives: 1- To observe the disposition of students to participate in the group task through the distribution of tasks, the discussion of ideas, the organization and the commitment for the work to carry out. 2- To observe in students the use of critical thinking in the analysis of data, in its interpretation and in the elaboration of conclusions and a laboratory report. The registered students in 2009 in the General and Biological Physics were distributed to groups of 6 members. Each group conducted the laboratory experience and a written report of every practical work (PW). Two categories, one for laboratory tasks and one for the laboratory notebook were used to evaluate the activities carried out by students. The obtained notes by group and PW under both headings depended on the group. The groups performances was better in the laboratory activities than in the notebook. The workgroup encouraged students to achieve a signifi cant learning. However, not having read the theoretical concepts limited the groups to take the initiative to begin the experience and it took them to read the guide simultaneously to fulfi l the PW. This lack of knowledge was also refl ected at the time of emitting the conclusions in the laboratory report
A proposal for a coordinated effort for the determination of brainwide neuroanatomical connectivity in model organisms at a mesoscopic scale
In this era of complete genomes, our knowledge of neuroanatomical circuitry
remains surprisingly sparse. Such knowledge is however critical both for basic
and clinical research into brain function. Here we advocate for a concerted
effort to fill this gap, through systematic, experimental mapping of neural
circuits at a mesoscopic scale of resolution suitable for comprehensive,
brain-wide coverage, using injections of tracers or viral vectors. We detail
the scientific and medical rationale and briefly review existing knowledge and
experimental techniques. We define a set of desiderata, including brain-wide
coverage; validated and extensible experimental techniques suitable for
standardization and automation; centralized, open access data repository;
compatibility with existing resources, and tractability with current
informatics technology. We discuss a hypothetical but tractable plan for mouse,
additional efforts for the macaque, and technique development for human. We
estimate that the mouse connectivity project could be completed within five
years with a comparatively modest budget.Comment: 41 page
Robust features for the automatic identification of autism spectrum disorder in children
Interpretación de las curvas del respirador en pacientes con insuficiencia respiratoria aguda
La ventilación mecánica es una intervención terapéutica de sustitución temporal de la función ventilatoria enfocada a mejorar los sÃntomas en los pacientes que sufren insuficiencia respiratoria aguda. Los avances tecnológicos han facilitado el desarrollo de ventiladores sofisticados que permiten visualizar y registrar las ondas respiratorias, lo que constituye una fuente de información muy valiosa para el clÃnico. La correcta interpretación de los trazados es de vital importancia tanto para el correcto diagnóstico como para la detección precoz de anomalÃas y para comprender aspectos de la fisiologÃa relacionados con la ventilación mecánica y con la interacción paciente-ventilador. El presente trabajo da una orientación de cómo interpretar las curvas del ventilador mediante el análisis de trazados de presión en la vÃa aérea, flujo aéreo y volumen en distintas situaciones clÃnicas.Facultad de Ciencias Médica
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