10-bit monolithic high-speed d.a. convertor

A bipolar monolithic high-speed 10-bit digital-analogue convertor is described. The chip size is 1.6 mm × 2.56 mm, the chip dissipation is 210 mW, and the maximum switching frequency is 100 MHz. Circuit diagram, processing details and characteristics are presented.     

Comparison of the lymphoid toxicities of mitobronitol and busulphan in mice: reduced B cell toxicity and improved thymic recovery as possible contributors to the reduced risk for complications following BMT with mitobronitol preconditioning

8-Carbamoyl-3-methylimidazo(5,1-d)-1,2,3,5-tetrazin-4(3H)-one (temozolomide) is a new imidazole tetrazinone compound with promising preclinical and clinical activity in nitrosourea-sensitive and -resistant models and manageable toxicity in Phase I and II clinical trials. In this study, we investigated the antiproliferative activity of temozolomide against a large variety of human tumors taken directly from patients in an in vitro soft agar tumor cloning system. Temozolomide was studied using a continuous exposure at final concentrations from 0.1 to 10.0 microM against a total of 222 tumor specimens, of which 101 (45%) were evaluable. A decrease in tumor colony formation was considered significant if survival of colonies treated with temozolomide was 相似文献   

Antagonist effect of insulin-like growth factor I on protein kinase inhibitor-mediated apoptosis in human glioblastoma cells in association with bcl-2 and bcl-xL

OBJECT: Tamoxifen (TAM) has been found to be effective in inhibiting proliferation of glioblastoma cells in vitro, but clinical studies have been disappointing. The purpose of this study was to determine whether insulin-like growth factor I (IGF-I), a potential autocrine/paracrine mitogen produced by glioblastomas, interferes with the antimitogenic actions of TAM. METHODS: Human glioblastoma cells were treated with or without TAM and/or IGF-I in vitro and evaluated for: viability by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenol tetrazolium bromide cleavage assay; apoptosis by histochemical analysis of nuclear morphology and 3'-OH DNA fragments; and expression of the IGF-I receptor, and the bcl-2, bcl-xL, and bax proteins by immunoblot analysis. In addition, p53 status was determined by DNA sequencing and by transient transfection with luciferase reporter plasmids containing wild-type or mutant p53. Results indicated that after 72 hours of exposure to 2 mg/ml TAM in vitro, 56.3% of WITG3 and 43.8% of U87-MG glioblastoma cells contained apoptotic nuclei (p < 0.01 compared with untreated cells). Apoptosis was independent of the presence of p53 because the WITG3 cells, in contrast to the U87-MG cells, expressed a mutant, nonfunctional p53. The WITG3 cells expressed IGF-I receptor proteins and demonstrated IGF-I binding. Exogenous IGF-I stimulated WITG3 cell proliferation and significantly (p < 0.05) antagonized the cytotoxic effects of TAM in a dose-dependent fashion; IGF-I, but not TAM, enhanced expression of bcl-2 and bcl-xL proteins; however, bax protein expression was unchanged by either treatment. CONCLUSIONS: Because many gliomas secrete large amounts of IGF-I in autocrine/paracrine growth pathways, these data may, in part, explain the failure of TAM to achieve clinical results as dramatic as those in vitro.     

Numerical analysis of singularities in two-dimensions part 1: Computation of eigenpairs

A numerical method is described for the computation of eigenpairs which characterize the exact solution of linear second-order elliptic partial differential equations in two dimensions in the vicinity of singular points. The singularities may be caused by re-entrant corners and abrupt changes in boundary conditions or material properties. Such singularities are of great interest from the point of view of failure initiation: The eigenpairs characterize the straining modes and their amplitudes quantify the amount of energy residing in particular straining modes. For this reason, failure theories directly or indirectly involve the eigenpairs and their amplitudes. This paper addresses the problem of determining the eigenpairs numerically on the basis of the Steklov formulation. Numerical results are presented for several cases. Importantly, the method is applicable to three-dimensional cases.     

Ion mixing at 20 keV: a comparison of the effects of Ga+, Ar+ and CF4+ ion irradiation

Medium-energy (some tens of keV) ion irradiation is frequently used in various technologies. It is well known that during this irradiation serious alterations are introduced to the material, changing its structure, composition, etc. While there are studies on the amorphization, no results have been reported on the medium-energy ion beam-induced mixing, however. In this work, we present Auger electron spectroscopy (AES) depth profiling measurements of Si/Cr multilayer samples, which were irradiated by various ions (Ga+, Ar+, CF4+) of 20 keV applying angles of incidence of 5 degrees (Ga+), 65 degrees (Ga+) and 75 degrees (Ar+, CF4+). The ion beam-induced mixing at the Si/Cr interface (the broadening of the interface) was measured as a function of the removed layer thickness. The weakest and strongest ion mixing (for a given removed layer thickness) were found for CF4+ and Ga+ 5 degrees irradiations, respectively. In the case of Ga+ irradiation, the larger the angle of incidence the weaker the ion mixing. The extent of mixing does not correlate with the corresponding projected range. Comparison of the experimentally measured ion mixed profiles with those given by dynamic TRIM simulations gave poor agreement for Ar+ and fails for Ga+ irradiations, respectively.     

Transactional Memory for Unstructured Mesh Simulations

In this paper we study transactional memory (TM) as a new tool for threading codes in this new era of multi- and many-core computers. In particular, we investigate the features and study the applicability of transactional memory as an efficient and easy-to-use alternative for handling memory conflicts in unstructured mesh simulations that use shared memory. The software tool used for our preliminary analysis of this novel construct is IBM’s freely available Software Transactional Memory (STM) system. For our studies, we developed the BUSTM benchmark which is a test code with state-of-the-art unstructured-mesh bookkeeping. The numerical algorithms are simplified yet still exhibit most of the salient features of modern unstructured mesh methods. We apply STM to two frequently used algorithm types used in multi-physics codes with realistic 3-D meshes. Our computational experiments indicate a good fit between these application scenarios and the TM features.     

Lycopene content and colour of ripening tomatoes as affected by environmental conditions

Tomatoes may have a great impact in the prevention of some types of cancer. This protective effect has been attributed to lycopene. The biosynthesis of lycopene is affected by environmental conditions. If the temperature of the fruits exceeds 30 °C, the synthesis of lycopene is inhibited. Strong direct radiation on fruits (～2990 µmol m^?2 s^?1 for 1.5–4 h) is harmful. In 2002, we investigated the effect of temperature and photosynthetically active radiation (PAR) on lycopene content. Fruit samples were harvested three times during the growing phase. The average lycopene content of harvested fruits, picked on 18 June 2002, reached 64.9 mg kg^?1 of fresh tomato. The fruits gathered on 25 June 2002 contained on average only 35.5 mg of lycopene per kilogram. The average lycopene content from the third harvest (on 9 July 2002) was 68.9 mg kg^?1. The values of PAR varied between 150 and 415 µmol m^?2 s^?1, so they did not exceed the critical value. The average temperature preceding the second harvest was the highest (28–32 °C) and the maximum temperature ranged between 40 and 43 °C. This prolonged, extremely high temperature may have caused the low lycopene level in the second harvest. The lycopene content of six ripeness stages, from green to deep red stage, was measured in 2002 and 2003. The accumulation of lycopene accelerates from the pink stage and there is a high correlation (R² = 0.92) between lycopene content and colour values (a*/b*). The higher the ratio of a*/b*, the higher was the lycopene content. Copyright © 2005 Society of Chemical Industry