一类工作点可变线性系统的镇定控制器设计

对于一类工作点可变的线性系统 ,即被控系统表达为两个典型工作点上的传递函数矩阵的正则稳定的既约分解的线性内插 ,考虑其镇定控制器设计问题 .假设被控对象在典型工作点上的传递函数矩阵的既约分解组成一个集合 ,提出了镇定该集合的控制器的设计方法 .对于线性内插系数不可知的情形 ,提出了两种固定型镇定控制器的设计方法 ;对于线性内插系数可知的情形 ,提出了一种内插型镇定控制器设计方法 .文中将控制器的设计问题转化为 H∞ 控制问题 ,再转化为状态空间下的基于线性矩阵不等式 ( LMI)的凸有效性问题进行求解     

Cloning, sequencing and expression of cDNA for a novel subunit of acetylcholine receptor from calf muscle

The nicotinic acetylcholine receptor (AChR) from fish electric organ has a subunit structure of alpha 2 beta gamma delta, and this is thought to be also the case for the mammalian skeletal muscle AChR. By cloning and sequencing the complementary or genomic DNAs, we have previously elucidated the primary structures of all four subunits of the Torpedo californica electroplax and calf muscle AChR and of the alpha- and gamma-subunits of the human muscle AChR; the primary structures of the gamma-subunit of the T. californica AChR and the alpha-subunit of the Torpedo marmorata AChR have also been deduced elsewhere. We have now cloned DNA complementary to the calf muscle messenger RNA encoding a novel polypeptide (the epsilon-subunit) whose deduced amino-acid sequence has features characteristic of the AChR subunits and which shows higher sequence homology with the gamma-subunit than with the other subunits. cDNA expression studies indicate that the calf epsilon-subunit, as well as the calf gamma-subunit, can replace the Torpedo gamma-subunit to form the functional receptor in combination with the Torpedo alpha-, beta- and delta-subunits.     

Production of 'hybrid' antibiotics by genetic engineering

The recent development of molecular cloning systems in Streptomyces has made possible the isolation of biosynthetic genes for some of the many antibiotics produced by members of this important genus of bacteria. Such clones can now be used to test the idea that novel antibiotics could arise through the transfer of biosynthetic genes between streptomycetes producing different antibiotics. The likelihood of a 'hybrid' compound being produced must depend on the substrate specificities of the biosynthetic enzymes, about which little is known. In attempts to demonstrate hybrid antibiotic production, we therefore began with strains producing different members of the same chemical class of compounds in order to maximize the chance of success. Here we report the production of novel compounds by gene transfer between strains producing the isochromanequinone antibiotics actinorhodin, granaticin and medermycin. These experiments were made possible by the recent cloning of the whole set of genes for the biosynthetic pathway of actinorhodin from Streptomyces coelicolor A3(2) (ref. 8). We believe that this represents the first report of the production of hybrid antibiotics by genetic engineering.     

Fibulin-5/DANCE is essential for elastogenesis in vivo.

The elastic fibre system has a principal role in the structure and function of various types of organs that require elasticity, such as large arteries, lung and skin. Although elastic fibres are known to be composed of microfibril proteins (for example, fibrillins and latent transforming growth factor (TGF)-beta-binding proteins) and polymerized elastin, the mechanism of their assembly and development is not well understood. Here we report that fibulin-5 (also known as DANCE), a recently discovered integrin ligand, is an essential determinant of elastic fibre organization. fibulin-5-/- mice generated by gene targeting exhibit a severely disorganized elastic fibre system throughout the body. fibulin-5-/- mice survive to adulthood, but have a tortuous aorta with loss of compliance, severe emphysema, and loose skin (cutis laxa). These tissues contain fragmented elastin without an increase of elastase activity, indicating defective development of elastic fibres. Fibulin-5 interacts directly with elastic fibres in vitro, and serves as a ligand for cell surface integrins alphavbeta3, alphavbeta5 and alpha9beta1 through its amino-terminal domain. Thus, fibulin-5 may provide anchorage of elastic fibres to cells, thereby acting to stabilize and organize elastic fibres in the skin, lung and vasculature.     

The role of sex steroid in two avian song behaviours differing in ontogenetic process

The male Bengalese finch,Lonchura striata, has two types of song behaviour (directed song, DS and undirected song, US). DS and US share a basically identical syllable repertoire, sequence pattern and tempo, but differ in the time course of appearance during the maturational process. In order to examine whether this results from a difference in testosterone (T) dependency, we studied developmental changes in the fecal T level and the amounts of DS and US during the 2–4 month period (N=7). DS appeared between 83 and 94 days of age, 4–16 days after a rise in the fecal T level. In contrast, US appeared earlier and at high frequency even when T was still at a very low level. These results suggest that DS is more dependent on the T level than US, and is not activated until the T level rises during the maturational process.     

Catecholamine content and uptake of the ductus arteriosus of the fetal lamb

Zusammenfassung Die Verteilung von Noradrenalin und Dopamin im Ductus arteriosus des Lammes wurde studiert und mit¹⁴C-Norepinephrin die Fähigkeit, exogenes Noradrenalin aufzunehmen, geprüft.     

Innate versus learned odour processing in the mouse olfactory bulb

The mammalian olfactory system mediates various responses, including aversive behaviours to spoiled foods and fear responses to predator odours. In the olfactory bulb, each glomerulus represents a single species of odorant receptor. Because a single odorant can interact with several different receptor species, the odour information received in the olfactory epithelium is converted to a topographical map of multiple glomeruli activated in distinct areas in the olfactory bulb. To study how the odour map is interpreted in the brain, we generated mutant mice in which olfactory sensory neurons in a specific area of the olfactory epithelium are ablated by targeted expression of the diphtheria toxin gene. Here we show that, in dorsal-zone-depleted mice, the dorsal domain of the olfactory bulb was devoid of glomerular structures, although second-order neurons were present in the vacant areas. The mutant mice lacked innate responses to aversive odorants, even though they were capable of detecting them and could be conditioned for aversion with the remaining glomeruli. These results indicate that, in mice, aversive information is received in the olfactory bulb by separate sets of glomeruli, those dedicated for innate and those for learned responses.