先进汽车电子产品及其相关存储器件

计算机和电子行业的进步最终给司机、乘客同汽车的互动方式带来了极其显著的变革。从汽车电子产品显示架构就可以清楚地看出,在未来很长一段时间内,电子系统的进步将会继续促进和影响汽车技术的发展(参见图1)。本文则将探讨一个问题:从一名汽车电子产品的设计师的角度来说,这些系统应该选用什么样的存储器?汽车电子系统用到了所有主要类型的存储器——SRAM、DRAM和非易失性存储器(non-volatile memory,NVM)。在下面的小节里,我们将考察它们在汽车电子产品中的应用方式。SRAMSRAM属于静态、随机存取的存储器件。其数据存储方式是静态…     

Pharmacokinetics and effect of food on the bioavailability of orally administered venlafaxine

Venlafaxine is a unique antidepressant currently under evaluation for treatment of various affective disorders. The pharmacokinetics and relative bioavailability of venlafaxine were evaluated in healthy volunteers after oral administration. The bioavailability of 50 mg of venlafaxine as a tablet relative to a solution was determined in a two-period randomized crossover study. The rate of absorption from the gastrointestinal tract was assessed by the time to peak plasma concentration (tmax), a model-dependent calculation of the first-order absorption rate constant, and a model-independent calculation of mean residence time. The extent of absorption was assessed by peak plasma concentration (Cmax) and area under the concentration-time curve (AUC). No statistically significant differences were observed between the two formulations for either the rate or extent of absorption. Similarly, systemic concentrations of the active O-demethylated metabolite did not significantly differ after administration of the two venlafaxine formulations. AUC ratios indicated that the relative bioavailabilities of the parent drug, and formulation of metabolite were approximately 98% and 92%, respectively, for the tablet versus the solution. A separate study was conducted to examine the influence of food on venlafaxine absorption from the 50-mg tablet. A standard, medium-fat breakfast eaten immediately before drug administration delayed the tmax of venlafaxine but did not affect Cmax or AUC. Therefore the tablet formulation of venlafaxine is bioequivalent to the oral solution, and the presence of food appears to decrease the rate but not the extent of absorption of venlafaxine from the tablet formulation.     

Angiotensinogen and angiotensin-I converting enzyme gene polymorphisms and the risk of coronary artery disease in Chinese

We investigated extracts of timothy grass pollen from four seasons (1989, 1990, 1991, and 1994) by protein content, SDS-PAGE, immunoblot, RAST, RAST inhibition, and crossed immunoelectrophoresis. Extract of the pollen from 1991 showed the lowest yield in quantitative assays. SDS-PAGE, crossed immunoelectrophoresis, RAST, and RAST inhibition expressed approximately comparable patterns for all extracts except that from 1991. Obviously, the quality of grass pollens, as shown for some ragweed (Ambrosia elatior) pollens depend on year of collection. Our findings are partially in agreement with some earlier examinations of the quality of timothy pollen from different pollen seasons.     

Geometrical birefringence in a class of step-index fiber

Based on a scalar wave equation including the geometrical effect, an effective-index method is developed for the calculation of geometrical birefringence, i.e., the difference in phase velocity between the two fundamental polarization modes, in a weakly guiding step-index fiber, of which the core can be of rectangular, elliptical, rhomboid or any other shape belonging to the same class, with arbitrary aspect ratio. Numerical results show that the method is very efficient and accurate in obtaining the birefringence and can also provide very useful information on the birefringenee-induced dispersion in the fiber.     

T lymphocyte-directed gene therapy for ADA- SCID: initial trial results after 4 years

In 1990, a clinical trial was started using retroviral-mediated transfer of the adenosine deaminase (ADA) gene into the T cells of two children with severe combined immunodeficiency (ADA- SCID). The number of blood T cells normalized as did many cellular and humoral immune responses. Gene treatment ended after 2 years, but integrated vector and ADA gene expression in T cells persisted. Although many components remain to be perfected, it is concluded here that gene therapy can be a safe and effective addition to treatment for some patients with this severe immunodeficiency disease.     

Pulsatile augmentation device for extracorporeal circulation

A device has been designed, constructed, and tested to provide pulsatile pressure/flow to a standard extracorporeal bypass circuit. The pulsatile augmentation device is pneumatically driven similar to an artificial heart ventricle except that there are no valves. It is constructed of polyurethane by vacuum forming and high frequency welding. Drivers used are a modified Arrow-Kontron intraaortic balloon pump or the Utah artificial heart driver. In vitro testing with fresh bovine blood demonstrated acceptable blood compatibility and hemodynamic function. In vivo testing for 4 h in a right and left heart extracorporeal bypass circuit showed good pulse augmentation in pulmonary and systemic bypass circuits. The device shows promise for adding pulse to standard cardiopulmonary bypass and to extracorporeal right heart circulatory assist circuits.     

Synthesis of four-bar function generators by means of equations of three relative poles—2. Mixed “point-order” synthesisMaßsynthese von viergelenkigen funktionsgetrieben unter benutzung von gleichungen drieier relativer pole II. Mittellung: Gemischte, ‘punkt-ordnung’ synthese

This is a continuation of the work described in Part 1[1]. For “order” type approximations the sythesis is based on an inversion linkage. Equations derived as variations from the three relative pole equation are presented for all four-position cases. For third and higher order approximations the procedure can be further simplified by using equations of the loci of the intersections of crank center lines.     

Multi-layer epitaxially grown silicon impatt diodes at millimeter-wave frequencies

Complementary (N⁺PP⁺) and double-drift (N⁺NPP⁺) silicon IMPATT diodes were prepared and investigated as oscillators in the millimeter-wave frequency region of 50 to 70 GHz. All the diodes were fabricated from multi-layer epitaxially grown silicon structures. A maximum CW output power level of 198 mW at 62.9 GHz and a maximum conversion efficiency of 7.3% have been measured for the complementary diodes. The double-drift IMPATT diodes have a maximum CW output power of 400 mW at 56.3 GHz and a maximum conversion efficiency of 8.5%.