8,431 research outputs found
CHARACTERISTIC OF FROZEN-THAWED EPIDIDYMAL SPERMATOZOA AND REFRIGERATED STORAGE OF RAM SPERMATOZOA
No full textPost-mortem spermatozoa recovery is an important technique for obtaining germplasm reserves
from genetically valuable animals or endangered species. The purpose of this study was to study
whether ram spermatozoa within epididymides stored at 4º C for 24 and 48 h remain their motility and
viability. The characteristic of ram epididymal spermatozoa after freezing and thawing was also
observed. Six pairs of ram testes with attached epididymides were used in this study. The motility of
control spermatozoa was well maintained throughout the dilution procedure (83.3±1.1, 80±1.3, and
80±1.3% for collection, Niwa and Sasaki freezing -1 extender (NSF-1 and NSF-2 groups respectively);
but declined (P<0.05) after freezing and thawing (38.3±3.1%). Motile and viable spermatozoa could be
recovered from epididymides up to 48 h of storage, although their quality declined significantly
(P<0.05) as post-mortem storage time increased (motility: 83±1.2, 67±3.0, and 46±5.1; viability:
84.2±2.4, 73±2.8, and 66.6±2.6 % for control, 24 h and 48 h group respectively). These data indicate
that ram epididymides could be stored at 4º C for 48 h when epididymal spermatozoa cannot be
immmediately collected and cryopreserved. These storage conditions might be possible to use for
epididymal sperm recovery in wild ruminants.
Keywords: epididymal spermatozoa, Freezing, ram, refrigeratio
Numerical simulation of ram extrusion in short-fiber-reinforced fresh cementitious composites
No full textThis is the author's accepted manuscript. The final published article is available from the link below. First published in JoMMS in 4(10), 2009, published by Mathematical Sciences Publishers.A series of ram extrusion tests was carried out on a short-fiber-reinforced, semisolid, fresh cementitious composite. An elastoviscoplastic constitutive model is proposed for the extrudable fresh cementitious composite. It features the associative flow rule, a nonlinear strain rate-hardening law, and the von Mises yield criterion. The model is then implemented in ANSYS/LS-DYNA explicit finite element code.
Various ram extrusion processes of the fresh cementitious composite were simulated. It has been found that the extrusion load versus imposed displacement predictions agree well with the experimental results. The fresh paste flow, through the die entry and the die-land, is then interpreted in light of the evolution of the deformation and distribution of state variables, mainly based on numerical results and the ram extrusion mechanism.
The effects of extrusion ratio and extrusion velocity on extrusion load are also investigated, based on the mechanical properties of the fresh cementitious composite. The study indicates that the numerical procedure established, together with the constitutive model proposed, is applicable for describing ram extrusion of short-fiber-reinforced fresh cementitious composites, which might provide a numerical rheometric tool from which ram extrusion of elastoviscoplastic paste-like materials can be examined and quantified.Hong Kong Research Grant Council and China Ministry of Science and Technology
C-RAM (Counter Rocket, Artillery and Mortar)
No full textEste trabalho de investigação aplicada visa estudar as principais capacidades do sistema C-RAM e a sua aplicabilidade no Exército Português, tendo por objetivo a caracterização e avaliação da possível constituição e modo de emprego de uma unidade C-RAM no Exército Português, de acordo com o poder de fogo, a capacidade radar e a mobilidade.
A metodologia de investigação adotada consiste no método analítico e inquisitivo, concretizado pela realização de entrevistas a Oficiais de Artilharia. Como principais conclusões, constatamos que os sistemas Phalanx e Oerlikon se evidenciam como os sistemas C-RAM de eleição, por disporem de alcances e cadências de tiro mais adequadas às necessidades da Artilharia Antiaérea Portuguesa no âmbito da proteção da força, ou de pontos e áreas críticas, contra este tipo de ameaças.This applied research work aims to study the main capabilitties of the C-RAM system and its applicability in the Portuguese Army. With the objective to characterize and evaluate the possible generation and employment of a C-RAM unit in the Portuguese Army, according to the firepower, radar capability and mobility. The research methodology adopted consists of analytical and inquisitive method, implemented by interviewing Artillery Officers. As main conclusions, we found thar Phalanx and Oerlikon systems are the C-RAM election systems, due to its range and rate of fire, more suited to the needs of Portuguese Air Defense Artillery regarding force protection, against this type of threats
Scientometric portrait of Ram Gopal Rastogi
No full textPublication productivity of Indian scientist (R.G. Rastogi) has been documented.
Scientometric analysis of 312 papers by Ram Gopal Rastogi published during 1954 to 1992 in various domains: (a) Luni -solar activity and quiet -time E & F- region (57); (b) Equatorial electric field and low and mid latitude iof:osphere (78); (c) Ionospheric E- region irregularities (19); (dj Ionospheric F- region irregularities (32); and (e) Magnetic disturbance effects on the equatorial low and mid latitude ionosphere (23) were analysed. Interdomainery contents and of the number of papers: a+b were 36; b+c and b+d were 20 each; b+e were 16;. c+e were 5; a+e were 3; d+e were 2; and a+d had only one publication. Highest collaborations were with H. Chandra (61), M.R. Deshpande (42), and G. Sethia (19) out of his total 97 collaborators. His highest productivity was during 1978 with 28 papers followed by 19 papers during 1977. The core journals preferred by him for publishing papers were: Indian Journal of Radio & Space Physics, India, and Journal of Atomic & Terrestrial Physics, UK (59 each), followed by Proceedings of the Indian Academy of Sciences, India (34). Most prolific title keywords with their frequencies were: Ionosphere (92); Equatorial (61); F-region (53); Equatorial electrojet region (40), and Magnetic equator (30)
Emprego e adaptação do método GMP-RAM para avaliação dos riscos das nanotecnologias.
No full textResumo: A Nanotecnologia está baseada na crescente capacidade da tecnologia moderna em manipular átomos e partículas na nanoescala para criar novos materiais e desenvolver novos produtos e processos. Ela promete grandes avanços nas mais diversas áreas de atuação, desde a Medicina à Engenharia de Materiais. Apesar dos materiais nanoestruturados apresentarem propriedades físicas diferentes do seu correspondente convencional, ainda não há metodologias para avaliação de riscos direcionadas ao uso intensivo desses novos materiais e substâncias químicas. Neste cenário, o presente trabalho propõe o emprego e adequação de uma metodologia comumente empregada para a avaliação de risco de transgênicos para o caso das nanotecnologias. O método GMP-RAM já foi empregado com sucesso para o caso do mamão geneticamente modificado para resistência ao vírus da mancha anelar. Abstract: Nanotechnology is based on the increasing power of modern technology to manipulate atoms and particles at the nanoscale to create new materials and develop new products and processes. It promises great advances in several areas of expertise, from medicine to Materials Engineering. Although engineered nanomaterials present different physical properties of its corresponding conventional, there are no methodologies for risk assessment to determine the intensive use of these new materials and chemicals. In this scenario, this study proposes the use and adequacy of a methodology commonly used for the risk assessment of transgenic for the case of nanotechnology. The GMP-RAM Method has already been used successfully to perform the case study of the papaya genetically modified for resistance to the ringspot virus
La banca extranjera en Am�rica Latina: resultado de su desempe�o
No full textLos sistemas financieros de todo el mundo han sufrido cambios profundos en los �ltimos 10 a�os; la desregulaci�n y apertura iniciada en los a�os setenta, ampliadas y profundizadas a finales de las d�cadas de los ochenta y noventa impulsaron la llegada de instituciones bancarias extranjeras en Am�rica Latina, destacando los espa�oles Banco Santander Central Hispano (bsch) y Banco Bilbao Vizcaya Argentaria (bbva), as� como el estadounidense Citibank, los cuales han acaparado el mercado y, con ello, generado concentraci�n de activos, pasivos, cartera crediticia y utilidades bancarias, adem�s de escasos niveles de crecimiento de ahorro, inversi�n y cr�ditos, as� como condiciones de vulnerabilidad y fragilidad para los sistemas bancarios de la regi�n. Este documento responde a dos cuestiones fundamentales: 1. �Cu�l y c�mo ha sido la presencia de la banca extranjera en la regi�n? y 2. �Cu�l ha sido el desempe�o de los bancos extranjeros en las naciones latinoamericanas
Nuevo registro de Cestrum mortonianum (Solanaceae) y descripci�n de una variedad en la vertiente pac�fica de M�xico
No full textSe revisa la distribuci�n de Cestrum mortonianum y se describe e ilustra una variedad de la Sierra de Manantl�n. Se discuten las caracter�sticas que la diferencian de C. mortonianum var. mortonianum, C. tomentosum y C. pacificum, las cuales tienen en com�n la presencia de pubescencia ramificada. Se proporciona una clave para separar las especies de Cestrum de M�xico con este tipo de indumento
Reconocimiento y dispersión de hongos causantes del "picamento" (Rayspeck) en crisantemo (Chrysanthemum morifolium ram) en condiciones de invernadero
No full textThe recongnition of the fungi causing ray speck and their dispersion in chrysantemum (Chrysanthemum morifolium RAM) cv. Polaris, was carried out under greenhouse conditions. Three speciea were identified: Alternaria alternata (FR) Keiasler, Alternaria zinniae Ellis, Stemphylium botryosum, Wallroth lPleospora herbarum) Raben Horst. The analysis ofthe disease dispersion was based on a random deaign with three repetitions. The number of coloniea, the temperature and relative humidity were evaluated in four different placea of the culture. The temperature was found to be the most important factor afecting the production and releaSe of conidia. The sporulation reached ita peak at noon (21°C)
Associação de produtores rurais de São José do Cerrito na Dinâmica de desenvolvimento rural: importância das feiras de gado
No full textTrabalho de Conclusão de Curso - Universidade Federal de Santa Catarina. Curso de Agronomia
Chalcogénures pour le stockage de l’information : mémoires ioniques (CB-RAM) et mémoires à changement de phase (PC-RAM)
No full textLes verres chalcogénures possèdent des propriétés uniques qui permettent d’envisager leur
utilisation pour le développement de mémoires électriques susceptibles de remplacer les
mémoires flash actuelles. D’une part, les verres sulfures et séléniures « dopés » par des
ions argent présentent une conductivité ionique élevée, propriété qui pourrait être mise à
profit pour le développement de mémoires ioniques CB-RAM. D’autre part, la haute
photosensibilité des tellurures – matériaux à changement de phase – a permis le succès du
développement puis de la commercialisation de dispositifs pour le stockage optique de
l’information (CD-RW, DVD-RW, BD). Ces dernières années, ces matériaux font l’objet
d’intenses recherches pour le développement de mémoires électriques PC-RAM. L’objectif de
cet article est d’apporter un éclairage sur ces matériaux et sur les mécanismes
susceptibles d’expliquer les commutations électriques en leur sein. Dans le cas des
mémoires ioniques CB-RAM, nous avons d’abord réalisé une caractérisation structurale et
électrique du matériau actif Agx(Ge0,25Se0,75)100-x sous forme de verre massif. Puis nous avons procédé à
une étude de la commutation électrique au sein de multi-couches minces
Ag/Ge25Se75 par une méthode innovante : la microscopie à force
atomique conductrice (C-AFM). Dans le cas des mémoires PC-RAM, une étude systématique de
couches épaisses amorphes du système GexTe100−x a été
effectuée afin d’établir une corrélation entre la structure et le vieillissement des
couches
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