在逆境中奋进的蓝牙技术

行业分析人士曾预测,蓝牙半导体市场会在2000年下半年开始攀升,而在2001年将持续攀升.尽管这些预测未达到期待的水平,但普遍地持乐观的态度,蓝牙技术有吸引力的市场仍在向我们召唤.对这一变幻无常的市场,很多半导体供应商趁修改和更新标准之际,纷纷改变了蓝牙产品研发计划.     

Mutation analysis of the MEN1 gene in multiple endocrine neoplasia type 1, familial acromegaly and familial isolated hyperparathyroidism

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant disease characterized by neoplasia of the parathyroid glands, the endocrine pancreas, and the anterior pituitary gland. In addition, families with isolated endocrine neoplasia, notably familial isolated hyperparathyroidism (FIHP) and familial acromegaly, have also been reported. However, whether these families constitute MEN 1 variants or separate entities remains speculative as the genetic bases for these diseases are unclear. The gene for MEN 1 has recently been cloned and characterized. Using single strand conformation analysis (SSCA) and sequencing, we performed mutation analysis in: a) a total of 55 MEN 1 families from 7 countries, b) 13 isolated MEN 1 cases without family history of the disease, c) 8 acromegaly families, and d) 4 FIHP families. Mutations were identified in 27 MEN 1 families and 9 isolated cases. The 22 different mutations spread across most of the 9 translated exons and included frameshift (11), nonsense (6), splice (2), missense mutations (2), and in-frame deletions (1). Among the 19 Finnish MEN 1 probands, a 1466del12 mutation was identified in 6 families with identical 11q13 haplotypes and in 2 isolated cases indicating a common founder. One frameshift mutation caused by 359del4 (GTCT) was found in 1 isolated case and 4 kindreds of different origin and haplotypes; this mutation therefore represents a common "warm" spot in the MEN1 gene. By analyzing the DNA of the parents of an isolated case one mutation was confirmed to be de novo. No mutation was found in any of the acromegaly and small FIHP families, suggesting that genetic defects other than the MEN1 gene might be involved and that additional such families need to be analyzed.     

Collaborative study on the use of motility enrichment on modified semisolid Rappaport-Vassiliadis medium for the detection of Salmonella from foods.

A collaborative study was performed in 15 laboratories to evaluate the use of motility enrichment on modified semisolid Rappaport-Vassiliadis (MSRV) medium for rapid Salmonella detection in a variety of food products. The results of this procedure were compared with those obtained by the cultural procedure using Rappaport-Vassiliadis (RV) broth as selective enrichment and modified brilliant green agar for selective plating. The tests were performed with Salmonella reference samples (SRS) as well as with naturally contaminated food products. When SRS were used without added food the productivity of both MSRV and RV was 96%. When SRS were combined with reference samples containing competitive bacteria the productivity was 98% for MSRV and 95% for RV. In the tests with food samples the productivity of MSRV was 92% with SRS added to food and 96% with naturally contaminated samples, while the productivity of RV was 88% and 90%, respectively. Statistical analysis showed that there was no significant difference between the procedures.     

Characterization of the human gonadotropin-releasing hormone receptor heterologously produced using the baculovirus/insect cell and the Semliki Forest virus systems

1. Two eukaryotic viral systems, the baculovirus/insect cell and the Semliki Forest virus systems, were tested for heterologous expression of human gonadotropin-releasing hormone receptor (GnRHR) cDNA. 2. An unmodified as well as a c-myc epitope-tagged human GnRH receptor was produced in two insect cell lines (Spodoptera frugiperda, Trichoplusia ni) after infection with the respective recombinant baculoviruses. In both insect cell lines, the receptor was identified by immunoblot analysis as a triplet of bands between 35 and 40 kDa. After deglycosylation of the receptor the molecular mass decreased to 35 kDa. The GnRH receptor was localized in membrane compartments within the infected insect cells. However, only in membranes of infected Trichoplusia ni insect cells could approximately 2000 receptors per cell be detected. 3. Production of the GnRH receptor in BHK cells using the Semliki Forest virus system resulted in approximately 50,000 receptors per cell. A maximal yield of 0.42 pmol/mg membrane protein was obtained 24 hr after electroporation of BHK cells with in vitro synthesized RNA. Binding of the antagonist [125I]Cetrorelix was saturable with a KD of 1.3 nM. The receptor produced in the BHK cells was further characterized by ligand displacement studies. The rank order of agonist and antagonist affinities was Cetrorelix > Triptorelin > Antide > GnRH.     

Exploring the role of the neighbourhood in firm relocation: differences between stayers and movers

Most firm relocations take place across rather short distances, indicating that firms are in general quite place-attached. Still, at the local level, weaker neighbourhoods are characterised by relatively high firm out-migration figures, which may be the result of unfavourable local business conditions. Through a qualitative study of 40 entrepreneurs from weaker neighbourhoods, equally divided between firms that relocated (movers) and firms that did not (stayers), this paper studies to what extent characteristics of the neighbourhood itself influence either past firm relocation decisions or future firm relocation propensity. The results show that the neighbourhood plays only a modest role in firm relocation decisions and propensity, and when neighbourhood characteristics are mentioned as push factors, they are in general outweighed by investments or relocation costs in the decision-making process. Because most firm relocation decisions, both in the past and in the future, are related to aspects of the business property, rather than consequences of other neighbourhood characteristics, maintaining or creating a diverse supply of business properties within a neighbourhood may prevent most potential movers from leaving the neighbourhood much more than neighbourhood liveability improvement measures.     

Cloning using nuclear transfer in bovine species: initial results

In 1987, Prather et al. have performed the first embryo cloning by nuclear transfer in the bovine species. Since, many researchers try to develop and to apply the technique. While the enucleation of the recipient oocyte, the injection of the donor blastomere and the fusion procedure are now well controlled, on the other hand, maturation and activation as the development and freezing of the cloned embryos need to be more investigated. The cloned embryo is more fragile. An increase in embryonic mortality is observed after transfer in a recipient cow.     

A technique for massive sky view factor calculations in large cities

In many applications, such as urban physics simulations or the study of the solar impact effects at different scales, complex 3D city models are required to evaluate physical values. In this article, we propose an efficient system for quickly computing the Sky View Factor (SVF) for a massive number of points inside a large city. To do that, we embed the city into a regular grid, and for each cell we select a subset of the geometry consisting of a square area centred in the cell and including it. Then, we remove the selected geometry from the city model and we project the rest onto a panoramic image, called environment map. Later, when several SVF evaluations are required, we only need to determine the cell that each evaluation point belongs to, and compute the SVF with the cell’s geometry plus its corresponding environment map. To test our system, we perform several evaluations inside a cell’s area, and compare the results with an accurate ray-tracing-based SVF evaluation. Our results show the feasibility of the method and its advantages when used for a large set of computations. We show that our tool provides a way to handle the complexity of urban scale models, and specifically allows working with geometry details if they are required.     

Combinatorial Design of Copper‐Based Mixed Nanoclusters: New Catalysts for Suzuki Cross‐Coupling

Quantum dots (2–5 nm) of copper and copper/palladium mixtures are found to be good catalysts for Suzuki cross‐coupling. The catalysts are applicable to a wide range of iodo‐ and bromoaryl substrates, and give moderate yields using chloroaryl substrates. Cluster activity and stability is found to depend strongly on the preparation method and the reaction conditions. The mechanism of cluster deactivation and the sensitivity of the cluster‐catalysed reaction to substituent effects are studied and discussed.