3,474 research outputs found

    Aspects of selection in an interbred flock based on Perendales crossed with Merino X Romney ewes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University

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    Genetic, phenotypic and environmental parameters were estimated from hogget traits recorded on 237 Perendale x (Merino x Romney) ewe hoggets between 1977 and 1984. Non-genetic effects on weaning weight (WW) for 634 ewe and ram lambs were analysed. A selection objective and criteria was defined and appraised for the flock. The traits examined were hogget liveweight (HLW), greasy fleece weight (GFW), clean fleece weight (CFW), quality number (QN), character grade (CHG), handle grade (HG), cotting grade (CG), soundness grade (SG), greasy colour grade (GCG), scoured colour grade (SCG), staple length (SL), total crimp number (TCN), clean scoured yield (Y), mean fibre diameter (MFD) and crimps per centimetre (CPC). The least squares method of fitting constants was used to estimate the major environmental factors influencing the traits studied. Heritabilities (h2) were obtained by the daughter-dam regression (DDR) and daughter-dam correlation (DDC) methods. The genetic (rG), phenotypic (rP) and environmental (rE) correlations were calculated by the daughter-dam method. The estimates of environmental effects agree in most cases with the published estimates. Between year differences were important sources of variation and had a highly significant effect on all traits except SCG. Rearing rank effect was found to be the most important source of variation for WW and HLW. Age of dam and sex had a highly significant effect on WW. Neither rearing rank nor age of dam exerted any significant influence on wool traits. The estimates of heritability calculated by daughter-dam regression method were: HLW (0.16), GFW (0.17), CFW (0.24), QN (0.42), CHG (0.38), SG (0.02), GCG (0.38), SCG (0.09), SL (0.12), TCN (0.08), Y (0.41) and MFD (0.29). Genetic and phenotypic correlations calculated among some hogget traits were respectively: HLW x GFW (0.67 and 0.66); HLW x CFW (0.62 and 0.56); HLW x SL (0.79 and 0.44); HLW x MFD (-0.45 and 0.24); GFW x CFW (0.87 and 0.94); GFW x SL (0.37 and 0.60); GFW x MFD (-0.98 and 0.38); CFW x GCG (0.52 and 0.02); QN x MFD (-0.79 and -0.30); SG x MFD (0.73 and -0.21); GCG x SCG (0.87 and 0.38); GCG x Y (0.96 and 0.04) and SCG x Y (0.77 and 0.00). Lifetime economic weights derived using the marginal profit method were calculated to define a selection objective for the flock studied. The traits included in the objective were number of lambs weaned (NLW (dam)), WW, CFW, MFD and SCG. Besides the traits in the objective, HLW, GFW, QN and GCG were included as selection criteria. The appropriate selection indices for ram hoggets (I1), ewe hoggets (I2) and lambs (I3 ) were respectively: I1 =4.66 NLW (dam) + 0.62 HLW + 0.10 WW + 3.91 GFW - 1.70 MFD + 0.50 GCG. I2 =4.79 NLW (dam) + 0.61 HLW + 0.04 WW + 1.99 GFW + 0.23 QN + 1.60 GCG. I3 = 4.87 NLW (dam) + 0.48 WW

    Excel files and MATLAB programs for numerical solution methods

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    Excel files and MATLAB programs for Chapter 5 of "Economic Growth: Theory and Numerical Solution Methods" published by Springer Verlag.

    Monte Carlo simulation of recrystallization

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    A Monte Carlo computer simulation technique, in which a continuum system is modeled employing a discrete lattice, has been applied to the problem of recrystallization. Primary recrystallization is modeled under conditions where the degree of stored energy is varied and nucleation occurs homogeneously (without regard for position in the microstructure). The nucleation rate is chosen as site saturated. Temporal evolution of the simulated microstructures is analyzed to provide the time dependence of the recrystallized volume fraction and grain sizes. The recrystallized volume fraction shows sigmoidal variations with time. The data are approximately fit by the Johnson-Mehl-Avrami equation with the expected exponents, however significant deviations are observed for both small and large recrystallized volume fractions. Under constant rate nucleation conditions, the propensity for irregular grain shapes is decreased and the density of two sided grains increases

    Impact of Power Allocation and Antenna Directivity in the Capacity of a Multiuser Cognitive Ad Hoc Network

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    This paper studies the benefits that power control and antenna directivity can bring to the capacity of a multiuser cognitive radio network. The main objective is to optimize the secondary network sum rate under the capacity constraint of the primary network. Exploiting location awareness, antenna directivity, and the power control capability, the cognitive radio ad hoc network can broaden its coverage and improve capacity. Computer simulations show that by employing the proposed method the system performance is significantly enhanced compared to conventional fixed power allocation

    Effect of Location Accuracy and Shadowing on the Probability of Non-Interfering Concurrent Transmissions in Cognitive Ad Hoc Networks

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    Cognitive radio ad hoc systems can coexist with a primary network in a scanning-free region, which can be dimensioned by location awareness. This coexistence of networks improves system throughput and increases the efficiency of radio spectrum utilization. However, the location accuracy of real positioning systems affects the right dimensioning of the concurrent transmission region. Moreover, an ad hoc connection may not be able to coexist with the primary link due to the shadowing effect. In this paper we investigate the impact of location accuracy on the concurrent transmission probability and analyze the reliability of concurrent transmissions when shadowing is taken into account. A new analytical model is proposed, which allows to estimate the resulting secure region when the localization uncertainty range is known. Computer simulations show the dependency between the location accuracy and the performance of the proposed topology, as well as the reliability of the resulting secure region

    Impact of biogenic very short-lived bromine on the Antarctic ozone hole during the 21st century

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    Active bromine released from the photochemical decomposition of biogenic very short-lived bromocarbons (VSL_Br ) enhances stratospheric ozone depletion. Based on a dual set of 1960-2100 coupled chemistry-climate simulations (i.e. with and without VSL Br ), we show that the maximum Antarctic ozone hole depletion increases by up to 14% when natural VSLBr are considered, in better agreement with ozone observations. The impact of the additional 5 pptv VSL Br on Antarctic ozone is most evident in the periphery of the ozone hole, producing an expansion of the ozone hole area of ~5 million km 2 , which is equivalent in magnitude to the recently estimated Antarctic ozone healing due to the implementation of the Montreal Protocol. We find that the inclusion of VSL Br in CAM-Chem does not introduce a significant delay of the modelled ozone return date to 1980 October levels, but instead affect the depth and duration of the simulated ozone hole. Our analysis further shows that total bromine-catalysed ozone destruction in the lower stratosphere surpasses that of chlorine by year 2070, and indicates that natural VSL Br chemistry would dominate Antarctic ozone seasonality before the end of the 21 st century. This work suggests a large influence of biogenic bromine on the future Antarctic ozone layer.Fil: Fernandez, Rafael Pedro. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España. Universidad Tecnologica Nacional. Facultad Regional Mendoza. Secretaría de Ciencia, Tecnología y Postgrado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Kinnison, Douglas E.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Lamarque, Jean Francois. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Tilmes, Simone. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; Españ

    Modelo de ISING en 3-d. aplicación a sensores magnéticos

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    El modelo de Ising es un problema de física estadística que tiene solución exacta en dos dimensiones, para el caso de tres dimensiones es preciso utilizar procedimientos de simulación. En este trabajo se ha utilizado un método de Monte Carlo para estudiar el comportamiento del sistema en distintas situaciones, siendo de especial interés el estudio del paso por la transición de fase a la temperatura crítica (Temperatura de Curie, Tc). Se ha estudiado la cinética de los dominios magnéticos, considerando la estructura de los dominios desde el punto de vista de la energía, y en consecuencia, hemos tenido en cuenta la energía de canje que tiende a mantener alineados los espines de los electrones en los materiales ferromagnéticos. Este término contribuye a hacer mayor el espesor de la pared, por la tendencia a que los espines de los átomos vecinos se mantengan alineados. Se ha considerado el ferromagnetismo desde el punto de vista cuántico y basado en las propiedades de simetría de las funciones de onda de los electrones, que se manifiestan en variaciones de la energía electrostática de un sistema en función de la orientación de sus espines. Se han estudiado los efectos de histéresis que resultan al aplicar un campo magnético externo a la red y la orientación de los espines de la misma a lo largo de su evolución. Para la determinación de las propiedades de los materiales ferromagnéticos se utiliza el ciclo de histéresis aunque algunas de las propiedades magnéticas, como la dirección de anisotropía, no pueden ser deducidas directamente de esta manera. Se utilizan distintos métodos para la determinación de la anisotropía de las muestras. El acoplamiento entre la magnetización en zonas próximas a la superficie y la magnetización en zonas internas de la muestra puede ser utilizado para obtener un ciclo de histéresis, que permita obtener sensores magnéticos adaptados a las medidas que se quieran realizar. Mediante el control del campo coercitivo y la susceptibilidad se abre una línea de investigación para el desarrollo de sensores magnético

    Ecosystems and Sustainable Metabolisms

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    The Strategic Plan for the Calderona Mountain Range (Valencia, Spain) covers an area of 200 km2 including 5 municipalities located at the northern edge of the Valencia’s Metropolitan Area. The Plan deals with a wide diversity of aspects, being ecology and sustainable development their common denominators. Thus, the analysis of the different territorial layers (forestry, agriculture, natural environment, urban planning, landscape, heritage, tourism & public use, mobility & infrastructures, and economic activity) was developed from an ecological and sustainability focused point of view which is afterwards extended in the definition of regional strategies and in a set of ten thematic plans and eighteen pilot projects. In particular, sustainability, the structural role of ecology and the effective enhancement of the different existing and potential ecosystems, permeate the whole Strategic Plan but are in particular the central elements of the Territorial and Landscape Plan, which includes the definition of a regional and local Green Infrastructure; of the Natural Environment Plan, which identifies the existing and potential plant communities and establishes the conditions for their adequate improvement and maintenance, and, finally, the Sustainable Development Plan, that analyzes the present flows of energy and resources and explores the territorial and urban models which would permit the reinforcement of internal metabolisms and the reduction of ecological footprints.Peer reviewe

    A heterogeneous "resting" pool of synaptic vesicles that is dynamically interchanged across boutons in mammalian CNS synapses

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    Using pHluorin-tagged synaptic vesicle proteins we have examined the partitioning of these probes into recycling and nonrecycling pools at hippocampal nerve terminals in cell culture. Our studies show that for three of the major synaptic vesicle components, vGlut-1, VAMP-2, and Synaptotagmin I, approximately 50-60% of the tagged protein appears in a recycling pool that responds readily to sustained action potential stimulation by mobilizing and fusing with the plasma membrane, while the remainder is targeted to a nonrecycling, acidic compartment. The fraction of recycling and nonrecycling (or resting) pools varied significantly across boutons within an individual axon, from 100% resting (silent) to 100% recycling. Single-bouton bleaching studies show that recycling and resting pools are dynamic and exchange between synaptic boutons. The quantitative parameters that can be extracted with the approaches outlined here should help elucidate the potential functional role of the resting vesicle pool
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