Dual-laser flow cytometry of single mammalian cells. [Performance of low-power argon and high-power krypton laser system for quantitative analysis and sorting of cells]

An improved dual-laser flow cytometric system for quantitative analysis and sorting of mammalian cells has been developed using a low-power argon and high-power krypton laser as illumination sources, thus permitting the excitation of fluorescent dyes having absorption regions ranging from the ultraviolet to infrared. Cells stained in liquid suspension with fluorescent dyes enter a flow chamber where they intersect two spatially separated laser beams. Separate pairs of quartz beam-shaping optics focus each beam onto the cell stream. Electro-optical sensors measure fluorescence and light scatter from cells that are processed electronically and displayed as frequency distribution histograms. Cells also can be electronically separated and microscopically identified. The ease and versatility of operation designed into this system represent a marked technological improvement for dual-laser excited flow systems. Details of this instrument are described along with illustrative examples of cells stained with mithramycin and rhodamine and analyzed for DNA content, total protein, and nuclear and cytoplasmic diameter

Material Requirements Planning: 25 anos de história - Uma revisão do passado e prospecção do futuro Material Requirements Planning: 25 years of history - An overview of the past and prospects of the future

Tomando como referência a publicação do livro MRP por J. Orlicky em 1975, este artigo se propõe a recuperar a gênese e desenvolvimento de um modelo de planejamento da produção bastante popular nas empresas. Em paralelo ao desenvolvimento da tecnologia da informação e das técnicas de gestão de operações, estes sistemas foram crescendo, alcançando hoje alto nível de abrangência e sofisticação. A aquisição e implantação de sistemas do porte dos atualmente disponíveis devem ser cercadas de uma série de cuidados, bem como de uma melhor compreensão do papel que estes sistemas podem desempenhar nas empresas. Esta revisão histórica visa proporcionar uma visão crítica com relação aos sistemas de gestão empresarial, seus riscos e potencialidades, e ainda estimular uma reflexão sobre seu futuro.<br>This paper intends to make a review over the development of a very popular production planning model in the enterprises, since the publication of the book 'MRP' of J. Orlicky in 1975. These systems have developed in parallel to the development of information technology and of operations management techniques, achieving a large scope and a high standard of sophistication. The acquisition and implementation of the large systems available nowadays must be based on a very careful approach and on a better understanding of the role of these systems in the organizations. This review also aims to show an analysis of the enterprise management systems, their risks and their potential, besides on a reflection about the future of such a kind of systems