916 research outputs found
Sudden Critical Current Drops Induced in S/F Structures
In the search for new physical properties of S/F structures, we have found
that the superconductor critical current can be controlled by the domain state
of the neighboring ferromagnet. The superconductor is a thin wire of thickness
d_{s} ~ 2 xi_{S}. Nb/Co and Nb/Py (Permalloy Ni_{80}Fe_{20}) bilayer structures
were grown with a significant magnetic anisotropy. Critical current
measurements of Nb/Co structures with ferromagnet thickness d_{F} > 30nm show
sudden drops in two very defined steps when the measurements are made along the
hard axes direction (i.e. current track parallel to hard anisotropy axes
direction). These drops disappear when they are made along the easy axis
direction or when the ferromagnet thickness is below 30nm. The drops are
accompanied by vortex flux flow. In addition magnetorestistance measurements
close to Tc show a sharp increase near saturation fields of the ferromagnet.
Similar results are reproduced in Nb/Py bilayer structure with the ferromagnet
thickness d_{F} ~ 50nm along the easy anisotropy axes. These results are
explained as being due to spontaneous vortex formation and flow induced by
Bloch domain walls of the ferromagnet underneath. We argue these Bloch domain
walls produce a 2D vortex-antivortex lattice structure.Comment: 6 pages, 6 figure
Final state interactions in semi-inclusive neutrino-nucleus scattering: Applications to the T2K and MINERν A experiments
Theoretical description of semi-inclusive T2K, MINERνA and MicroBooNE neutrino-nucleus data in the relativistic plane wave impulse approximation
Análisis del tamaño de partÃculas en areniscas de las Catedrales de Salamanca. Independencia entre granulometrÃa y deterioro
11 sandstone samples from the cathedrals of Salamanca were analysed granulometrically. The study was to establish whether there is a direct connection between the particle size of such stone and the surface deterioration of some of the ashlars in the facades. This was carried out with the help of diffraction spectrometry by laser beams.
The results show that there is no connection between the nature of the stone texture and their degree of surface deterioration.Se analizan granulométricamente 11 muestras de arenisca de las Catedrales de Salamanca. El objetivo del estudio es establecer si existe relación directa entre el tamaño de las partÃculas de tales piedras y el deterioro superficial de alguno de los sillares de las fachadas. Esto se lleva a cabo con la ayuda de la espectrometrÃa de difracción por rayos láser.
Los resultados muestran que no hay conexión entre la finura textural de las piedras estudiadas y el grado de deterioro superficial que éstas presentan
Semi-inclusive charged-current neutrino-nucleus cross sections in the relativistic plane wave impulse approximation
Neutrino-nucleus quasielastic scattering is studied in the plane wave impulse
approximation for three nuclear models: the relativistic Fermi gas (RFG), the
independent-particle shell model (IPSM) and the natural orbitals (NO) model
with Lorentzian dependence of the excitation energy. A complete study of the
kinematics of the semi-inclusive process and the associated cross sections are
presented and discussed for 40 Ar and 12 C. Inclusive cross sections are also
obtained by integrating the semi-inclusive expressions over the outgoing
hadron. Results are consistent with previous studies restricted to the
inclusive channel. In particular, a comparison with the analytical results for
the RFG model is performed. Explicit expressions for the hadronic tensor and
the 10 semi-inclusive nuclear responses are given. Theoretical predictions are
compared with semi-inclusive experimental data from T2K experiment.Comment: 55 pages, 22 figures, submitted to Physical Review
Development policy planning in Ghana: The case of health care provision
This paper examines the historical development of health policy in
Ghana within the framework of financial, geographical accessibility and the
availability of health care. Historically, health policy has been
urban biased, and largely focused on financial accessibility. Even Nkrumah's
free health care policy could not adequately address the problem of
inadequate health professionals and facilities in the rural areas.The study also
established that poverty is also largely a rural phenomenon.The poor benefit
less from the National Health Insurance Scheme (NHIS). This situation
makes the NHIS lack social equity, the very reason for its being. We
recommend that government should expand health facilities in the rural areas,
and introduce attractive incentive packages to attract and retain health
professionals in such areas. There is an urgent need for rigorous criteria
to be developed by the NHIS to identify the very poor for health insurance
premium exemptions
ANALYZING AND PRICE FORECASTING FOR SELECTED GRAIN CLASSIFIED AS BIOMASS FEEDSTOCK ON THE EU MARKETS
The paper deals with the price trends of biomass feedstock used as renewable energy sources. Special attention is paid to kind of grain classified as the particular sort of biomass in Poland. The comparative prices analysis of some selected kind of grain on the markets of the EU countries is presented in this paper. Also there was demonstrated validity of two forecast models in order to forecast the prices for one month. After the forecasting, the accuracy was evaluated as well as the validation forecasts allowing for evaluation
Smallholder Dairy Farmers in the Peruvian Andes Fulfilling the Role of Extension Agents
Dairy farming in the Peruvian Andes is mostly undertaken by smallholder farmers (4-6 cows/family) and of relatively recent development. In fact, over the last 2 decades dairy farming at high altitudes (3,500‒4200 masl) has grown rapidly, replacing the camelids and sheep farming that once predominated. Dairying growth has been catalysed by subsides from state and private organizations. It promotes high input systems based on feedlot technology. Compared to sheep and camelids farming, dairying at the Andes does not have yet an inherent local/indigenous knowledge associated to it. High altitude Andean ecosystems pose many constraints for dairy farming (hypoxia and high UV radiation, high variation between day and night temperatures, short rainy season, and hence shortage of feed and water; and not less importantly, accelerated climate change (CC)). Under these conditions, not only are productivity and profitability low, but there are high negative environmental impacts and poor animal welfare. In Peru, institutionalised research and extension (R&E) services are precarious. Research tackling current issues of high-altitude livestock farming is almost inexistent, whereas extension in support of farmers is dispersed, poorly funded, of short duration (a few months), focused on transfer of technology suitable to intensive farming systems, and has a high turnover of staff. A systems approach to address the complexity of Andean livestock farming development is lacking. The initiatives from the institutions promoting farming are directed to remediate recurrent problems (e.g., cold stress) or prioritise high cost, low impact activities (e.g., genetic improvement). Here, we present the successful experience of the New Zealand Peru Dairy Support Project (NZPDSP) to promote the adoption of improved low input pastoral dairying husbandry principles, where trained smallholder farmers play a key role as agents of change
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