最佳短期投资方式

--转眼已到下半年的投资期了,金融市场上瞬息万变,投资机会来得快也去得快.那么最近美国人忙着投资什么呢?     

Peptide amidating activity in human bronchoalveolar lavage fluid

Monitoring respiratory epithelial biology may reveal individuals with incipient lung cancer. The expression of neuroendocrine (NE) markers in pulmonary epithelium is thought to be central to lung development, repair of injury and may contribute to carcinogenesis. In this study, we evaluate several candidate NE markers to determine the feasibility of prospective analysis of clinical specimens. The potential NE markers include the enzyme L-DOPA decarboxylase (DDC), the neuropeptide gastrin releasing peptide (GRP), and peptidyl-glycine alpha-amidating monooxygenase (PAM), the bifunctional enzyme responsible for the final bioactivation step of many neuropeptides. A comparison of PAM activity and DDC levels in 30 lung cancer cell lines indicated that peptide amidating activity may be an indicator of NE status. Bronchoalveolar lavage (BAL) fluid from subjects at risk of developing second primary lung cancer and from volunteers was obtained. The activity of the first PAM enzyme, peptidylglycine alpha-hydroxylating monooxygenase (PHM), ranged from not detectable to 507 pmol/h/mg protein in 57 specimens. The second PAM enzyme, peptidylamidoglycolate lyase (PAL), ranged from not detectable to 414 pmol/h/mg protein in 56 specimens. Using cluster analysis by the average linkage method, a group of enzyme values with PHM greater than 230 pmol/h/mg protein was determined. Long-term follow-up of these patients for new second primary lung cancers may help to determine the potential predictive value of PAM detected in the BAL fluid.     

Psychologists in Schools of Public Health: Current Status, Future Prospects, and Implications for Other Health Settings.

The deans and departmental chairs of the 22 schools of public health were asked in 1981 to list all psychologists holding full-time faculty appointments and the names of courses with a substantial behavioral/psychological content. Responses were received from 98% of the departments. The psychologists were then sent a survey concerning their backgrounds, job responsibilities, and satisfaction/dissatisfaction with their positions. There was an 80% response rate. Psychologists accounted for 5.7% of the approximately 1,300 full-time faculty in schools of public health. Psychologists represented a larger percentage of the faculty in departments of behavioral science than in departments of epidemiology, biostatistics, environmental health, and so forth. Public health psychologists were active researchers and publishers, with average totals of 2.5 articles and 26.9 citations for a three-year period. The primary advantages of employment in a school of public health had to do with an appreciation of the public health perspective, an interdisciplinary orientation, and research opportunities. The primary dissatisfactions cited were financial insecurity, isolation from psychology, and lack of appreciation among public health colleagues of the contribution of psychology to public health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and Biological Characterization of (Z)-9-Heptadecenoic and (Z)-6-Methyl-9-Heptadecenoic Acids: Fatty Acids with Antibiotic Activity Produced by Pseudozyma flocculosa

Difficulties in isolating and purifying antibiotic fatty acids from culture filtrates of Pseudozyma flocculosa, a biocontrol agent against powdery mildew, have been limiting factors in studying the properties and understanding the mode of action of the biocontrol agent. We report a new protocol for synthesizing (Z)-9-heptadecenoic and for the first time synthesis of (Z)-6-methyl-9-heptadecenoic acids, two antibiotic fatty acids produced by P. flocculosa. This allowed reproducible and quantifiable means of assaying biological activity of the molecules. In these bioassays, both molecules exhibited antifungal activity corresponding to their expected potency. These new developments should facilitate further studies aimed at deciphering the ecological properties of P. flocculosa.     

401[k]--美国人的养老金计划

401(k)养老金计划一直是美国人生活中不可或缺的重要组成部分.它起源于19世纪年代初美国税法修改、相关免税条款的出台.其名称来自<国内税收法案>第401(k)节,它允许员工将一部分税前工资存入一个储蓄计划,积累至退休后使用,在此基础上,一种新的养老金计划一"401(k)"开始出现,并大受欢迎.到2000年底其资产规模已达17000亿美元,参与人数超过4200万.     

Dynamics and succession of coastal dune vegetation in the Eastern Cape, South Africa

Mobile or partially vegetated dunefields dominate the Eastern Cape coastline, with dune slacks being conspicuously well vegetated. Earlier studies on the dynamics of these habitats suggested that greater soil moisture, reduced sand movement and salt spray favoured the establishment of more mesic species. Since an understanding of these successional processes has important management implications, more detailed studies to firstly describe and then interpret the successional relationships between various plant communities were undertaken. From a survey of 152 relevés at 62 sites, seven coastal communities were recognised by TWINSPAN. This separation appeared to be based on the location, habitat and successional stages of the communities, and ordination by DECORANA showed that in any one area these communities were linked to a succession gradient from pioneer to “climax”. A more detailed investigation of the role played by dune slacks in this succession was undertaken at Kleinemonde. Six communities were separated by TWINSPAN. Pioneer communities of the foredunes had low cover and diversity, being dominated by herbs. Young dune slacks had low cover but moderately high diversity, with sedges and grasses dominating. Old dune slacks had a greater total mean cover, and shrubs were more abundant. Bushclumps were physiognomically more complex than dune slacks, with greater total mean cover, diversity and life form composition. Thicket margin communities were structurally similar to bushclumps, but floristically more complex. Dune thicket was the most physiognomically and floristically complex community sampled. Multivariate analysis revealed a distinct gradient of plant communities with increasing distance (age) from the sea, namely from Pioneer to Young Slack, Old Slack, Bushclump, Thicket Margin and Dune Thicket communities. With age, species richness, cover, diversity, number of life forms and structural complexity of the communities all increased. Importance value curves for 12 diagnostic species highlighted the distribution of these key species along the chronosequence. Pioneer species were restricted to the beginning, and dune slack species the central portion of the chronosequence. Hardy species had a wide distribution, but dune thicket species only appeared later. These trends appear to represent directional changes along a successional sequence as proposed in an earlier model, and the mode of transition between them relies heavily on autogenic changes. Dune slacks play an important role in this facilitation by acting as centres of diversity within the sparsely vegetated dunefield, and the foredunes by protecting dune slacks from salt spray and sand movement. Therefore, the role of foredunes and dune slacks must be considered in the management of the South African dune landscape, as they contribute significantly to the dynamic equilibrium of partly vegetated dunefields. Management should therefore be aimed at protecting these habitats.     

Generating rooted triangulations without repetitions

We use the reverse search technique to give algorithms for generating all graphs onn points that are 2- and 3-connected planar triangulations withr points on the outer face. The triangulations are rooted, which means the outer face has a fixed labelling. The triangulations are produced without duplications inO(n ²) time per triangulation. The algorithms useO(n) space. A program for generating all 3-connected rooted triangulations based on this algorithm is available by ftp.This research was supported by N.S.E.R.C. Grant Number A3013, F.C.A.R. Grant Number EQ1678, and a bilateral exchange from J.S.P.S./N.S.E.R.C.