28 research outputs found
Um estudo dos problemas de projeto de matrizes de portas com tecnologia CMOS
This work discusses the aspects related to the basic cell features, and the problems f general array structure. The basic array sizing and spacing parameters, and eletrical and eletrical design problems are evaluated. An analysis of some peripheral circuits, with simulation results, is done. Finally, the results of a greate array reversal engineering are also shown.Este trabalho abrange desde aspectos ligados Ă s caracterĂsticas da cĂ©lula básica, atĂ© os problemas da estrutura geral da matriz. SĂŁo avaliados os parâmetros para dimensionamento e espaçamento dos dispositivos da matriz básica, alĂ©m dos problemas elĂ©tricos de projeto. É feita uma análise dos principais tipos de circuitos de periferia, com apresentação dos resultados de simulação. Finalmente, os resultados obtidos na engenharia reversa de uma matriz de portas sĂŁo tambĂ©m apresentados
Multiplus: a modular high-performance multiprocessor
The MULTIPLUS project is currently under development at NCE/UFRJ, Brazil, aims at the study of parallel processing problems in MIMD environments. The project includes the development of a parallel shared-memory architecture and a UNIX-like operating operating system called MULTIPLIX. The MULTIPLUS achitecture uses an inverted n-cube multistage network to interconnect clusters of processing nodes designed around a double-bus system. As a consequence, the architecture is partitionable and modular. It cas easily and efficiently supportconfigurations ranging from workstations to powerful parallel supercomputers with up to 2048 processing nodes. The MULTIPLix operating system provides MULTIPLUS with an efficient computing environment for parallel scientific applications. MULTIPLIX uses the concept of thread, implements busy-waiting synchronization primitives very efficiently and carefully considers data locality and scientific processing requirements in the policies adopted for memory management and thread scheduling.O projeto MULTIPLUS, que está atualmente em desenvolvimento no NCE/UFRJ, objetiva o estudo de problemas de processamento paralelo em ambiente MIMD. O projeto inclui o desenvolvimento de uma arquitetura paralela com memĂłria compartilhada e um sistema operacional tipo UNIX chamado MULTIPLIX. A arquitetura do MULTIPLUS usa uma rede de interconexĂŁo multiestágio do tipo n-cubo invertido para interligar clusters de nĂłs de processamento projetados em torno de um sistema de barramento duplo. Como consequĂŞncia a arquitetura Ă© patrocinável e modular. Ela pode suportar eficientemente configurações cobrindo um espectro que vai desde estações de trabalho atĂ© poderosos supercomputadores contendo 2048 nĂłs de processamento trabalhando em paralelo. O sistema operacional MULTIPLIX provĂŞ o MULTIPLUS com um ambiente eficiente de computação para aplicações cientĂficas paralelas.O MULTIPLIX usa o conceito de "thread", implementa primitivas de sincronização de espera ocupara muito eficientemente e considera fortemente aspectos de localidade dos dados e requisitos de processamento cientĂfico nas polĂticas adotadas para gerenciamento de memĂłria e escalonamento de "threads"
Influence of O6-benzylguanine on the anti-tumour activity and normal tissue toxicity of 1,3-bis(2-chloroethyl)-1-nitrosourea and molecular combinations of 5-fluorouracil and 2-chloroethyl-1-nitrosourea in mice
Previous studies have demonstrated that novel molecular combinations of 5-fluorouracil (5FU) and 2-chloroethyl-1-nitrosourea (CNU) have good preclinical activity and may exert less myelotoxicity than the clinically used nitrosoureas such as 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). This study examined the effect of O6-alkylguanine-DNA-alkyltransferase (ATase) depletion by the pseudosubstrate O6-benzylguanine (BG) on the anti-tumour activity and normal tissue toxicity in mice of three such molecular combinations, in comparison with BCNU. When used as single agents at their maximum tolerated dose, all three novel compounds produced a significant growth retardation of BCNU-resistant murine colon and human breast xenografts. This in vivo anti-tumour effect was potentiated by BG, but was accompanied by severe myelotoxicity as judged by spleen colony forming assays. However, while tumour resistance to BCNU was overcome using BG, this was at the expense of enhanced bone marrow, gut and liver toxicity. Therefore, although this ATase-depletion approach resulted in improved anti-tumour activity for all three 5-FU:CNU molecular combinations, the potentiated toxicities in already dose-limiting tissues indicate that these types of agents offer no therapeutic advantage over BCNU when they are used together with BG. © 1999 Cancer Research Campaig
Um estudo sobre redes de interconexão e a sua utilização no projeto MULTIPLUS
This paper presents a general study on interconnection networks and some particular aspects related to the Multiplus project. The first two chapters are devoted to a review of the subject relatedmatters (definitions, classifications, etc.) In chapter 3, the internal structure of a switch is discussed in more details. In the next chapter some of the major problems related to interconnection networks are focused under the context of parallel machines. Following, a brief analysis of some existing parallel architectures and their respective interconnection networks is given. Finally, some specific characteristics of the Multiplus project related to interconnection networks are presented and analyzed.Este trabalho apresenta um estudo geral sobre redes de interconexĂŁo e algumas caracterĂsticas particulares ligadas ao projeto Multiplus. Nos 2 primeiros capĂtulos Ă© feita uma revisĂŁo (definições, classificações, etc.) do assunto. No capĂtulo 3, Ă© vista com mais detalhes a estrutura interna de uma chave. No capĂtulo seguinte sĂŁo discutidos alguns dos principais problemas relacionados a redes de interconexĂŁo, dentro do contexto global de uma máquina paralela. Em seguida, sĂŁo apresentadas algumas arquiteturas paralelas existentes e suas respectivas redes e, por fim, sĂŁo apresentadas e analisadas algumas caracterĂsticas particulares do projeto Multiplus, relacionadas a redes de interconexĂŁo