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An indirect, phase-locked-loop (PLL), GaAs-enhanced frequency synthesizer with 700 ns loop settling time has been developed. The two-chip GaAs insertion reduced the size of an existing synthesizer from 90 in3 to only 30 in3. The 6.0 in×5.5 in.×0.9 in module contains a 400 gate GaAs programmable divider and a sample and hold (S/H) which improved the settling time by 77% and reduced the size by 67% over the current state-of-the-art synthesizer. Furthermore, the divider reduced power dissipation by 9.7 W and the S/H reduced power dissipation by 1.3 W  相似文献   
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分辨率增强技术(RET)设计流程中聚集了各式各样的点工具和方法。当前对深亚波长可制造性(DFM)设计的要求迫使设计与制造行业必须建立十分密切的合作关系。同时也促使EDA行业提供一种平台,以促进这些行业间的密切交流。合理利用这一平台将会对产能和品质产生直接的影响。  相似文献   
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Certain germline mutations (607Arg-Gln, 608Arg-Lys) in the androgen receptor gene have been associated with the occurrence of breast cancer in males suffering from partial androgen insensitivity. To assess whether somatic mutations in this gene could be detected in breast carcinoma, archival tumor tissue of males without clinical evidence of androgen insensitivity was screened for point mutations in the androgen receptor gene. DNA was retrieved by chloroform-phenol extraction from formalin-fixed, paraffin-embedded tissues. Exons 2-8 of the androgen receptor gene, encoding the DNA- and hormone-binding regions of the receptor, were amplified by polymerase chain reaction and subjected to nonisotopic single strand conformation assay (SSCA) to screen for point mutations. In the tumor DNA, no variations suggestive of mutations were encountered on SSCA. However, in a control patient with partial androgen insensitivity and predominantly female phenotype, the germline mutation 607Arg-Gln was identified in blood leukocyte DNA. Our results indicate that somatic mutations of the androgen receptor are not required for the development of male breast cancer. This, however, does not exclude an increased risk of breast carcinoma in patients with androgen insensitivity.  相似文献   
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A gasoline release site at the Dept. of Defense Housing Facility (DODHF) in Novato, Calif., resulted in dissolved methyl tertiary-butyl ether (MTBE) in a shallow, thin, heterogeneous aquifer. Multiple methods were used to evaluate the stability of the MTBE plume, including concentration versus time plots, isoconcentration contour maps, total dissolved MTBE mass and center of mass (COM) estimates, total plume extent changes, and parametric and nonparametric statistical techniques. The COM evaluation revealed a small upgradient shift in COM relative to both total plume extent and total MTBE mass reduction over the period examined. The total mass removal received substantial contributions from both the southern and northern portions of the plume, and the only removal mechanisms active in the northern plume were natural attenuation mechanisms. The results indicate that there exists at DODHF Novato a dissolved MTBE plume at the approximate balancing point between groundwater advection, which is carrying MTBE downgradient, and natural attenuation processes including aerobic biodegradation, which are reducing MTBE concentrations at about the same rate.  相似文献   
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New and improved catalytic processes for clean fuels   总被引:2,自引:0,他引:2  
New and more stringent environmental legislation is expected to have a major impact on the refining industry. Reformulated gasoline which is currently being introduced into parts of the United States is an example of the shift towards cleaner burning fuels. To achieve future government specifications for such fuels significant changes will likely be required in refinery operations to produce products with good combustion characteristics and reduced emissions.Catalysis is expected to play a dominant role in both modifying existing processes and developing new routes to these more environmentally acceptable fuels. Both new and improved catalysts systems which will be required for the production of so-called reformulated gasoline are discussed. For example, oxygenated components in gasoline such as methyl tertiary butyl ether (MTBE) will continue to be required on a large scale necessitating new process and catalyst technology to achieve improved economics.Natural gas can be considered as a clean feedstock from which to produce liquid fuels of high quality. A number of new process routes to convert remote natural gas into readily transportable liquid fuels are also discussed. This area of technology offers considerable scope for further major improvements based on innovation in the field of syngas catalysis.  相似文献   
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Scanning near-field optical microscopy of a cell membrane in liquid   总被引:1,自引:0,他引:1  
The applications of scanning near‐field optical microscopy to biological specimens under physiological conditions have so far been very rare since common techniques for a probe–sample distance control are not as well suited for operation in liquid as under ambient conditions. We have shown previously that our own approach for a distance control, based on a short aperture fibre probe and a tuning fork as force sensor in a tapping mode, works well even on soft material in water. By means of an electronic self‐excitation circuit, which compensates for changes of the resonance frequency due to evaporation of liquid, the stability of the force feedback has now been further improved. We present further evidence for the excellent suitability of the tapping‐mode‐like distance control to an operation in liquid, for example, by force‐imaging of double‐stranded DNA. Moreover, we demonstrate that a nuclear envelope in liquid can be imaged with a high optical resolution of ~70 nm without affecting its structural integrity. Thereby, single nuclear pores in the nuclear envelope with a nearest neighbour distance of ~120 nm have been optically resolved for the first time.  相似文献   
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(1) Background: The exact mechanism(s) underlying pathological changes in a heart in transition to hypertrophy and failure are not yet fully understood. However, alterations in cardiac energy metabolism seem to be an important contributor. We characterized an in vitro model of adrenergic stimulation-induced cardiac hypertrophy for studying metabolic, structural, and functional changes over time. Accordingly, we investigated whether metabolic interventions prevent cardiac structural and functional changes; (2) Methods: Primary rat cardiomyocytes were treated with phenylephrine (PE) for 16 h, 24 h, or 48 h, whereafter hypertrophic marker expression, protein synthesis rate, glucose uptake, and contractile function were assessed; (3) Results: 24 h PE treatment increased expression of hypertrophic markers, phosphorylation of hypertrophy-related signaling kinases, protein synthesis, and glucose uptake. Importantly, the increased glucose uptake preceded structural and functional changes, suggesting a causal role for metabolism in the onset of PE-induced hypertrophy. Indeed, PE treatment in the presence of a PAN-Akt inhibitor or of a GLUT4 inhibitor dipyridamole prevented PE-induced increases in cellular glucose uptake and ameliorated PE-induced contractile alterations; (4) Conclusions: Pharmacological interventions, forcing substrate metabolism away from glucose utilization, improved contractile properties in PE-treated cardiomyocytes, suggesting that targeting glucose uptake, independent from protein synthesis, forms a promising strategy to prevent hypertrophy and hypertrophy-induced cardiac dysfunction.  相似文献   
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