复数,实数及实对称数据下Bruun FFT算法的实现

本文在复数、实数以及实对称数据下研究和实现了Ｂｒｕｕｎ ＦＦＴ算法。文章分析和评价了各种数据下ＢｒｕｕｎＦＦＴ的运算量和特点，提出了算法的实现结构和方法。最后给了ＴＭＳ３２０Ｃ３０上的运算时间，我们实现的算法比基２ＦＦＴ速度提高３５％。     

ICOS is essential for effective T-helper-cell responses

The outcome of T-cell responses after T-cell encounter with specific antigens is modulated by co-stimulatory signals, which are required for both lymphocyte activation and development of adaptive immunity. ICOS, an inducible co-stimulator with homology to CD28, is expressed on activated, but not resting T cells, and shows T-cell co-stimulatory function in vitro. ICOS binds specifically to its counter-receptor B7RP-1 (refs 5,6,7), but not to B7-1 or B7-2. Here we provide in vivo genetic evidence that ICOS delivers a co-stimulatory signal that is essential both for efficient interaction between T and B cells and for normal antibody responses to T-cell-dependent antigens. To determine the physiological function of ICOS, we generated and characterized gene-targeted ICOS-deficient mice. In vivo, a lack of ICOS results in severely deficient T-cell-dependent B-cell responses. Germinal centre formation is impaired and immunoglobulin class switching, including production of allergy-mediating IgE, is defective. ICOS-deficient T cells primed in in vivo and restimulated in vitro with specific antigen produce only low levels of interleukin-4, but remain fully competent to produce interferon-gamma.     

Biochemistry: a cadmium enzyme from a marine diatom

The ocean biota contains a vast reservoir of genomic diversity. Here we present the sequence and preliminary characterization of a protein that is a cadmium-containing carbonic anhydrase from the marine diatom Thalassiosira weissflogii. The existence of a cadmium enzyme in marine phytoplankton may indicate that there is a unique selection pressure for metalloenzymes in the marine environment, and our discovery provides a long-awaited explanation for the nutrient-like behaviour of cadmium in the oceans.     

Organization and sequences of the variable, joining and constant region genes of the human T-cell receptor alpha-chain

An essential property of the immune system is its ability to generate great diversity in antibody and T-cell immune responses. The genetic and molecular mechanisms responsible for the generation of antibody diversity have been investigated during the past several years. The gene for the variable (V) region, which determines antigen specificity, is assembled when one member of each of the dispersed clusters of V gene segments, diversity (D) elements (for heavy chains only) and joining (J) segments are fused by DNA rearrangement. The cloning of the beta-chain of the T-cell antigen receptor revealed that the organization of the beta-chain locus, which is similar to that of immunoglobulin genes, is also composed of noncontiguous segments of V, D, J and constant (C) region genes. The structure of the alpha-chain seems to consist of a V and a C domain connected by a J segment. We report here that the human T-cell receptor alpha-chain gene consists of a number of noncontiguous V and J gene segments and a C region gene. The V region gene segment is interrupted by a single intron, whereas the C region contains four exons. The J segments, situated 5' of the C region gene, are dispersed over a distance of at least 35 kilobases (kb). Signal sequences, which are presumably involved in DNA recombination, are found next to the V and J gene segments.     

西部农业信息化建设问题的探讨

西部农业信息化水平低下制约着西部农业的发展。物质基础薄弱、信息意识淡薄、信息人才及资金短缺是造成西部农业信息化水平低下的原因。为加快西部信息化农业建设，应该从更新观念、加大政府支持力度、利用有限资源进行信息化基础建设、重视人才资源的开发、培育信息产品市场、加强农业应用系统和信息化农业技术的研究、加强示范应用体系等方面入手。     

室内通风系统气流噪声预测方法的改进

管道气流噪声是室内通风系统中的常见问题．由于后期改造十分困难，在设计阶段对由管道内障碍物等因素产生的气流噪声进行精确的预测计算是非常必要的．目前已有一些管道气流噪声预测的基本方法，但是很多预测手段都基于传统声学测量得到的数据．笔者近来不依赖于传统的测量数据，研究了运用计算流体动力学理论对管道内气流噪声进行预测的可行性，文中讨论了采用该方法遇到的问题以及近期在采用计算流体动力学计算气流噪声方面的研究工作。