建构 现实性的戏剧与建筑戏剧的真相

文章讨论了建构与技术、与人的身体的关系,揭示了现代主义以来建构概念所面临的威胁。通过对建构概念历史发展的回顾,作者指出建构概念本身亦应随时代变化而加以充实,现代主义对自由的追求在本质上与古老的建构概念并不矛盾,建构所展现的真实是一种表象,是对真实的诠释,是转译而非简单的赤裸裸的直陈。     

Electric Fatigue in Antiferroelectric Lead Zirconate Stannate Titanate Ceramics Prepared by Spark Plasma Sintering

The fatigue behavior of lead zirconate stannate titanate (PZST) ceramics prepared by spark plasma sintering (SPS) was investigated. Polarization and strain hysteresis loops were monitored. The material shows a high resistance to fatigue because of bipolar electric cycling. Both maximum strain and switchable polarization first show a fatigue stage 0 to 10⁵ cycles and then a fatigue-free period up to 10⁸ cycles. The maximum losses of maximum strain and switchable polarization are 18% and 10% of their initial values, respectively. The dominant fatigue mechanism is assigned to the pinning of domain walls by charged defects.     

CASE-BASED REASONING

Case-based reasoning (CBR) is an alternative to traditional rule-based expert systems approaches. The fact that rules can be incomplete and must be assembled through a time-consuming knowledge acquisition process has been a major bottleneck in the usefulness of rule-based methods for configuring information systems. Case-based reasoning systems, by contrast, access problem-solving experiences or cases for the next problem-solving situation. The CBR process, some commercial shells, and CBR's use to augment expert systems applications are discussed.     

A phase I study of adenovirus-mediated wild-type p53 gene transfer in patients with advanced non-small cell lung cancer

Mutations of the tumor suppressor gene p53 are the most common genetic alterations observed in human cancer. Loss of wild-type p53 function impairs cell cycle arrest as well as repair mechanisms involved in response to DNA damage. Further, apoptotic pathways as induced by radio- or chemotherapy are also abrogated. Gene transfer of wild-type p53 was shown to reverse these deficiencies and to induce apoptosis in vitro and in preclinical in vivo tumor models. A phase I dose escalation study of a single intratumoral injection of a replication-defective adenoviral expression vector encoding wild-type p53 was carried out in patients with incurable non-small cell lung cancer. All patients enrolled had p53 protein overexpression as a marker of mutant p53 status in pretreatment tumor biopsies. Treatment was performed either by bronchoscopic intratumoral injection or by CT-guided percutaneous intratumoral injection of the vector solution. Fifteen patients were enrolled in two centers, and were treated at four different dose levels ranging from 10(7) to 10(10) PFU (7.5 x 10(9) to 7.5 x 10(12) particles). No clinically significant toxicity was observed. Successful transfer of wild-type p53 was achieved only with higher vector doses. Vector-specific wild-type p53 RNA sequences could be demonstrated in posttreatment biopsies of six patients. Transient local disease control by a single intratumoral injection of the vector solution was observed in four of those six successfully transduced patients. There was no evidence of clinical responses at untreated tumor sites. Wild-type p53 gene therapy by intratumoral injection of a replication-defective adenoviral expression vector is safe, feasible, and biologically effective in patients with advanced non-small cell lung cancer.     

Right ventricular apical view--a new window for Doppler echocardiography of aortic valve stenosis

We studied a new Doppler echocardiographic approach in 56 patients with valvular aortic stenosis from the right ventricular apex (AS-RV) and compared the transvalvular gradients with the results of the standard view from the left ventricular apex (AS-LV). AS-RV resulted in good or acceptable velocity curves in 59% of patients. The correlation between the two apical views for the peak/mean gradients were close (r = 0.95/0.96). Using all typical positions for Doppler investigation of aortic stenosis, highest peak gradients were best recorded in five cases by AS-RV. In one woman with a narrow left ventricular cavum and severe aortic stenosis, only AS-RV yielded a technically good spectral curve. Thus, in selected patients--probably those with a small left ventricular cavity or an enlarged right ventricle--AS-RV may be the best window or even the only possibility in Doppler investigation of aortic valve stenosis.     

High-temperature electron mobilities in LPE-Grown GaP

We report measurements to 500°C of resistivity and Hall mobility in Sn-doped, n-type GaP grown by liquid phase epitaxy. Samples with room-temperature carrier densities between 1 × 10¹⁶ and 1 × 10¹⁸cm⁻³ were studied. Mobilities were in the range 100–180 cm²/V-sec at room temperature and in the range 27–35 cm²/V-sec at 400°C. Carrier densities increased by only about a factor of two with increasing temperature. Theoretical fits to the mobility data were made by considering contributions from intervalley, polar-optic, acoustic-deformation-potential, and ionlzed-impurity scattering mechanisms. Our results confirm the utility of GaP for high-temperature device applications and provide important information on electrical parameters needed for device modeling and design.     

Multiwavelength performance of an apodized acousto-optic switch

Use of the acousto-optic switch as a wavelength-routing element in WDM networks is described. The need for deep isolation between wavelength channels has resulted in the search for efficient sidelobe suppression techniques such as tapering of the acousto-optic profile by imbedding an optical waveguide in one arm of an acoustic directional coupler. The theory of sidelobe-suppression in the optical transmission function of a SAW-coupler apodized acousto-optic filter is presented. A low-sidelobe SAW-coupler-apodized AO switch was fabricated and used in a 1.5 micron multi-wavelength WDM switching demonstration employing four 4 nm-spaced optical channels. Crosstalk was below -19 dB for single wavelength selection and below -15 dB for arbitrary routing patterns, a dramatic improvement over unapodized AO switches