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  • 1
    Electronic Resource
    Electronic Resource
    A 16 cm broad-beam ion source for ion-beam etching of quartz wafers : Proceedings of the 6th international conference on ion sources (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1009-1011 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broad-beam ion source is developed for ion-beam etching of quartz wafers, which are used in resonators with a high basic frequency of the order of magnitude of 1 GHz. The improvement of uniformity of the extracted ion beam is investigated. The double-grid multiple-aperture ion optics is adopted, in which perveance is matched by varying both the aperture diameters and spaces between grids. The configuration of the magnetic field is optimized. Measured at the target of 12 cm from the grids, the area of uniform region (nonuniformity 〈5%) is approximately equal to the area of the bored region of the grids (12 cm diam) and 1/1.78 of the cross-section area of the anode (16 cm diam). A broad beam of 100–1000 eV and 0.1–2.0 mA/cm2 is extracted from the source to fulfill the requirement of the etching process. Without any cooling system, the ion source is installed in vacuum chamber. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146799
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  • 2
    Electronic Resource
    Electronic Resource
    On the Nature of PSE Approximation (1996)
    Springer
    Theoretical and computational fluid dynamics 8 (1996), S. 253-273 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract  The recently developed method of parabolized stability equations (PSE) offers a fast and efficient way of analyzing the spatial growth of linear and nonlinear (convective) disturbances in shear layers. For incompressible flows, the governing equations may be represented either in primitive variables or by using other formulations obtained by eliminating the pressure gradient (e.g., vorticity—streamfunction formulation). On the other hand, for compressible flows, primitive variables offer a natural and the only choice. We show that primitive-variable formulation is not well-posed due to the ellipticity introduced by the term and the marching solution eventually blows up for a sufficiently small step size. However, it is shown that this difficulty can be overcome if the minimum step size is greater than the inverse of the real part of the streamwise wave number, An alternative is to drop the term, in which case the residual ellipticity is of no consequence for marching computations with much smaller step sizes. However, the ellipticity cannot be completely removed. Results obtained with streamfunction and vorticity–velocity formulations also show that the numerical difficulties arise for a sufficiently small marching step size. This step-size restriction can be overcome by dropping the term from the governing equations. The effect of this term on solution accuracy is negligible for Blasius flow but not so for rotating-disk flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00639695
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  • 3
    Electronic Resource
    Electronic Resource
    Sugars act as signal molecules and osmotica to regulate the expression of α-amylase genes and metabolic activities in germinating cereal grains (1996)
    Springer
    Plant molecular biology 30 (1996), S. 1277-1289 
    Details
    ISSN: 1573-5028
    Keywords: α-amylase gene ; metabolic control ; osmotic control ; feedback control ; rice ; sugar signal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The molecular mechanisms that initiate and control the metabolic activities of seed germination are largely unknown. Sugars may play important roles in regulating such metabolic activities in addition to providing an essential carbon source for the growth of young seedlings and maintaining turgor pressure for the expansion of tissues during germination. To test this hypothesis, we investigated the physiological role of sugars in the regulation of α-amylase gene expression and carbohydrate metabolism in embryo and endosperm of germinating rice seeds. RNA gel blot analysis revealed that in the embryo and aleurone cells, expression of four α-amylase genes was differentially regulated by sugars via mechanisms beyond the well-known hormonal control mechanism. In the aleurone cells, expression of these α-amylase genes was regulated by gibberellins produced in the embryo and by osmotically active sugars. In the embryo, expression of two α-amylase genes and production of gibberellins were transient, and were probably induced by depletion of sugars in the embryo upon imbibition, and suppressed by sugars influx from the endosperm as germination proceeded. The differential expression of the four α-amylase genes in the embryo and aleurone cells was probably due to their markedly different sensitivities to changes in tissue sugar levels. Our study supports a model in which sugars regulate the expression of α-amylase genes in a tissue-specific manner: via a feedback control mechanism in the embryo and via an osmotic control mechanism in the aleurone cells. An interactive loop among sugars, gibberellins, and α-amylase genes in the germinating cereal grain is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019558
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  • 4
    Electronic Resource
    Electronic Resource
    On the nature of PSE approximation (1996)
    Springer
    Theoretical and computational fluid dynamics 8 (1996), S. 253-273 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The recently developed method of parabolized stability equations (PSE) offers a fast and efficient way of analyzing the spatial growth of linear and nonlinear (convective) disturbances in shear layers. For incompressible flows, the governing equations may be represented either in primitive variables or by using other formulations obtained by eliminating the pressure gradient (e.g., vorticity-streamfunction formulation). On the other hand, for compressible flows, primitive variables offer a natural and the only choice. We show that primitive-variable formulation is not well-posed due to the ellipticity introduced by the $$\partial \hat p/\partial x$$ term and the marching solution eventually blows up for a sufficiently small step size. However, it is shown that this difficulty can be overcome if the minimum step size is greater than the inverse of the real part of the streamwise wave number, αr. An alternative is to drop the $$\partial \hat p/\partial x$$ term, in which case the residual ellipticity is of no consequence for marching computations with much smaller step sizes. However, the ellipticity cannot be completely removed. Results obtained with streamfunction and vorticity-velocity formulations also show that the numerical difficulties arise for a sufficiently small marching step size. This step-size restriction can be overcome by dropping thedα/dx term from the governing equations. The effect of this term on solution accuracy is negligible for Blasius flow but not so for rotating-disk flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00639695
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  • 5
    Electronic Resource
    Electronic Resource
    Transgenic approaches to increase dehydration-stress tolerance in plants (1999)
    Springer
    Molecular breeding 5 (1999), S. 493-503 
    Details
    ISSN: 1572-9788
    Keywords: dehydration stress ; detoxifying enzymes ; lea genes ; osmoprotectants ; regulatory genes ; transgenic approaches
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant productivity is strongly influenced by abiotic stress conditions induced by drought, high salt and low temperature. Plants respond to these conditions with an array of biochemical and physiological adaptations, at least some of which are the result of changes in gene expression. Transgenic approaches offer a powerful means of gaining valuable information to better understand the mechanisms governing stress tolerance. They also offer new opportunities to improve dehydration-stress tolerance in crops by incorporating a gene involved in stress protection into species that lack them. In this review, we discuss progress made towards understanding the molecular elements involved in dehydration-stress responses that have been used to improve salt or drought tolerance following several transgenic approaches. Further, we discuss various strategies being used to produce transgenic plants with increased tolerance to dehydration stress. These include the overproduction of enzymes responsible for biosynthesis of osmolytes, late-embryogenesis-abundant proteins and detoxification enzymes. At this time, there is a need for a careful appraisal of the genes to be selected and promoter elements to be used, because constitutive expression of these genes may not be desirable in all applications. In this context, the advantages and limitations of transgenic approaches currently being used are discussed together with the importance of using stress-inducible promoters and the introduction of multiple genes for the improvement of dehydration-stress tolerance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009660413133
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  • 6
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    On the Nature of PSE Approximation (1996)
    Springer
    Details
    Publication Date: 1996-08-01
    Print ISSN: 0935-4964
    Electronic ISSN: 1432-2250
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 7
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    On the nature of PSE approximation (1996)
    Springer
    Details
    Publication Date: 1996-07-01
    Print ISSN: 0935-4964
    Electronic ISSN: 1432-2250
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 8
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    A 16 cm broad‐beam ion source for ion‐beam etching of quartz wafers (1996)
    American Institute of Physics
    Details
    Publication Date: 1996-03-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics
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  • 9
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    Genetic Correction of p67phox Deficient Chronic Granulomatous Disease Using Peripheral Blood Progenitor Cells as a Target for Retrovirus Mediated Gene Transfer (1997)
    American Society of Hematology
    Details
    Publication Date: 1997-03-01
    Description: Chronic granulomatous disease (CGD) can result from any of four single gene defects involving the components of the superoxide (O−2 ) generating phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. We show that transduction of peripheral blood CD34+ hematopoietic progenitors from a p67phox deficient CGD patient with replication defective amphotropic retrovirus encoding p67phox (MFGS-p67phox) significantly corrected the CGD functional defect in phagocyte oxidase activity in vitro. Using a chemiluminescence assay of oxidase activity, we showed that transduced patient CD34+ progenitors differentiating to myeloid cells in culture produced 25% of the total superoxide produced by normal CD34+ progenitors differentiating in culture. A flow cytometric assay of oxidase activity used to assess the oxidase function of individual cells in the cultures indicated that up to 32% of maturing granulocytes derived from transduced CD34+ progenitors from the p67phox CGD patient were oxidase positive with the average level of correction per granulocyte of 85% of that seen with granulocytes in similar cultures of CD34+ progenitors from normal volunteers. Nitroblue tetrazolium dye reduction assays of colonies of transduced progenitors in soft agar indicated that in some studies restoration of oxidase activity occurred in myeloid cells within 44% of granulocyte-erythrocyte-monocyte colonies, and within 28% of the combined group of granulocyte colonies/monocyte colonies/granulocyte-monocyte colonies. These high correction rates were achieved without any selective regimen to enrich for transduced cells. This study provides a basis for development of gene therapy for the p67phox deficient form of CGD.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 10
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    Genetic Correction of p67phox Deficient Chronic Granulomatous Disease Using Peripheral Blood Progenitor Cells as a Target for Retrovirus Mediated Gene Transfer (1997)
    American Society of Hematology
    Details
    Publication Date: 1997-03-01
    Description: Chronic granulomatous disease (CGD) can result from any of four single gene defects involving the components of the superoxide (O−2 ) generating phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. We show that transduction of peripheral blood CD34+ hematopoietic progenitors from a p67phox deficient CGD patient with replication defective amphotropic retrovirus encoding p67phox (MFGS-p67phox) significantly corrected the CGD functional defect in phagocyte oxidase activity in vitro. Using a chemiluminescence assay of oxidase activity, we showed that transduced patient CD34+ progenitors differentiating to myeloid cells in culture produced 25% of the total superoxide produced by normal CD34+ progenitors differentiating in culture. A flow cytometric assay of oxidase activity used to assess the oxidase function of individual cells in the cultures indicated that up to 32% of maturing granulocytes derived from transduced CD34+ progenitors from the p67phox CGD patient were oxidase positive with the average level of correction per granulocyte of 85% of that seen with granulocytes in similar cultures of CD34+ progenitors from normal volunteers. Nitroblue tetrazolium dye reduction assays of colonies of transduced progenitors in soft agar indicated that in some studies restoration of oxidase activity occurred in myeloid cells within 44% of granulocyte-erythrocyte-monocyte colonies, and within 28% of the combined group of granulocyte colonies/monocyte colonies/granulocyte-monocyte colonies. These high correction rates were achieved without any selective regimen to enrich for transduced cells. This study provides a basis for development of gene therapy for the p67phox deficient form of CGD.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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