S-containing amino acids can lead to two types of local NH···S interactions which bridge backbone NH sites to the side chain to form either intra- or inter-residue H-bonds. The present work reports on the conformational preferences of S-methyl-l-cysteine, Cys(Me), using a variety of investigating tools, ranging from quantum chemistry simulations, gas-phase UV and IR laser spectroscopy, and solution state IR and NMR spectroscopies, on model compounds comprising one or two Cys(Me) residues. We demonstrate that in gas phase and in low polarity solution, the C- and N-capped model compound for one Cys(Me) residue adopts a preferred C5–C6γ conformation which combines an intra-residue N–H···O=C backbone interaction (C5) and an inter-residue N–H···S interaction implicating the side-chain sulfur atom (C6γ). In contrast, the dominant conformation of the C- and N-capped model compound featuring two consecutive Cys(Me) residues is a regular type I β-turn. This structure is incompatible with concomitant C6γ interactions, which are no longer in evidence. Instead, C5γ interactions occur, that are fully consistent with the turn geometry and additionally stabilize the structure. Comparison with the thietane amino acid Attc, which exhibits a rigid cyclic side chain, pinpoints the significance of side chain flexibility for the specific conformational behavior of Cys(Me).
A total of 1347 weaned lambs from eight genotypes were tested over five consecutive years: Romanov (ROM) and Lacaune (LAC) pure breeds, the two F1 crossbreeds (RL and LR) and the offspring of ewes from these four genotypes sired with Berrichon-du-Cher rams (BCF). The lambs were individually exposed to three challenging tests involving novelty, human contact and social isolation. Ten synthetic variables were used to express social reactivity (i.e., active vs. passive strategy), exploratory activity and reactivity to humans. BCF crossbreds were more active (i.e., high bleats, locomotion and attempts to escape) than purebreds and F1. In contrast, ROM expressed more passive responses (i.e., low bleats and vigilance postures) than LAC and BCF crossbreds. In addition, ROM approached a motionless human less and had longer flight distances to an approaching human than did LAC and BCF crossbreds. When restrained, ROM, and to a lesser extent B×ROM and B×LR, avoided human contact more than did LAC, RL and B×LAC. Most of these differences were explained by direct additive genetic effects while maternal influences or heterosis effects were rarely significant. The highest heritability was for high bleats (h2 = 0.48). Females were more active and avoided human contact more than did males. 相似文献
The genetic diversity of Cylindrospermopsis strains (cyanobacteria) was examined using mainly the 16S-23S internally transcribed spacer (ITS1) sequences. Strains were grouped in three clusters: (i) America, (ii) Europe, and (iii) Africa and Australia. These results suggested a recent spread of Cylindrospermopsis across the American and European continents from restricted warm refuge areas instead of exchanges between continents. On the other hand, they also suggested a recent colonization of Australia by African strains. 相似文献
Palaeolimnological data from six mesotrophic, eutrophic and hypertrophic lakes in the Irish Ecoregion, in the form of microfossil
(cladocera, diatoms and pollen) and sediment chemistry data from radiometrically dated sediment cores, were used to reconstruct
past variations in lake water quality and catchment conditions. Basal sediments from sediment cores from the six sites ranged
in age from the late 18th century to the early 20th century. A weighted averaging partial least squares regression model was
developed to reconstruct past epilimnetic total phosphorus concentrations. The results indicate that all but one of the study
sites currently are in a far more productive state compared with the beginning of the sediment core record and that those
same five lakes have experienced accelerated enrichment post c. 1980. Two of the sites demonstrated long-term enrichment,
in one case beginning in the late 19th century, while both eutrophication and oligotrophication have occurred at three sites.
The results highlight the difficulties in applying a general temporal end-point for reference conditions and demonstrate that
productive lakes in the Irish Ecoregion have complex, locally specific and often long histories of enrichment. These may not
be responsive to reduced external loadings of phosphorus and, as a result, restoration could prove particularly challenging.
The results also provide evidence of the ways in which palaeolimnological techniques can assist implementation of the EU Water
Framework Directive.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
Application scheduling plays an important role in high-performance cluster computing. Application scheduling can be classified
as job scheduling and task scheduling. This paper presents a survey on the software tools for the graph-based scheduling on
cluster systems with the focus on task scheduling. The tasks of a parallel or distributed application can be properly scheduled
onto multi-processors in order to optimize the performance of the program (e.g., execution time or resource utilization).
In general, scheduling algorithms are designed based on the notion of task graph that represents the relationship of parallel
tasks. The scheduling algorithms map the nodes of a graph to the processors in order to minimize overall execution time. Although
many scheduling algorithms have been proposed in the literature, surprisingly not many practical tools can be found in practical
use. After discussing the fundamental scheduling techniques, we propose a framework and taxonomy for the scheduling tools
on clusters. Using this framework, the features of existing scheduling tools are analyzed and compared. We also discuss the
important issues in improving the usability of the scheduling tools.
This work is supported by the Hong Kong Polytechnic University under grant H-ZJ80 and by NASA Ames Research Center by a cooperative
grant agreement with the University of Texas at Arlington.
Jiannong Cao received the BSc degree in computer science from Nanjing University, Nanjing, China in 1982, and the MSc and the Ph.D degrees
in computer science from Washington State University, Pullman, WA, USA, in 1986 and 1990 respectively. He is currently an
associate professor in Department of Computing at the Hong Kong Polytechnic University, Hong Kong. He is also the director
of the Internet and Mobile Computing Lab in the department. He was on the faculty of computer science at James Cook University
and University of Adelaide in Australia, and City University of Hong Kong. His research interests include parallel and distributed
computing, networking, mobile computing, fault tolerance, and distributed software architecture and tools. He has published
over 120 technical papers in the above areas. He has served as a member of editorial boards of several international journals,
a reviewer for international journals/conference proceedings, and also as an organizing/programme committee member for many
international conferences. Dr. Cao is a member of the IEEE Computer Society, the IEEE Communication Society, IEEE, and ACM.
He is also a member of the IEEE Technical Committee on Distributed Processing, IEEE Technical Committee on Parallel Processing,
IEEE Technical Committee on Fault Tolerant Computing, and Computer Architecture Professional Committee of the China Computer
Federation.
Alvin Chan is currently an assistant professor at the Hong Kong Polytechnic University. He graduated from the University of New South
Wales with a Ph.D. degree in 1995 and was subsequently employed as a Research Scientist by the CSIRO, Australia. From 1997
to 1998, he was employed by the Centre for Wireless Communications, National University of Singapore as a Program Manager.
Dr. Chan is one of the founding members and director of a university spin-off company, Information Access Technology Limited.
He is an active consultant and has been providing consultancy services to both local and overseas companies. His research
interests include mobile computing, context-aware computing and smart card applications.
Yudong Sun received the B.S. and M.S. degrees from Shanghai Jiao Tong University, China. He received Ph.D. degree from the University
of Hong Kong in 2002, all in computer science. From 1988 to 1996, he was among the teaching staff in Department of Computer
Science and Engineering at Shanghai Jiao Tong University. From 2002 to 2003, he held a research position at the Hong Kong
Polytechnic University. At present, he is a Research Associate in School of Computing Science at University of Newcastle upon
Tyne, UK. His research interests include parallel and distributed computing, Web services, Grid computing, and bioinformatics.
Sajal K. Das is currently a Professor of Computer Science and Engineering and the Founding Director of the Center for Research in Wireless
Mobility and Networking (CReWMaN) at the University of Texas at Arlington. His current research interests include resource
and mobility management in wireless networks, mobile and pervasive computing, sensor networks, mobile internet, parallel processing,
and grid computing. He has published over 250 research papers, and holds four US patents in wireless mobile networks. He received
the Best Paper Awards in ACM MobiCom’99, ICOIN-16, ACM, MSWiM’00 and ACM/IEEE PADS’97. Dr. Das serves on the Editorial Boards
of IEEE Transactions on Mobile Computing, ACM/Kluwer Wireless Networks, Parallel Processing Letters, Journal of Parallel Algorithms
and Applications. He served as General Chair of IEEE PerCom’04, IWDC’04, MASCOTS’02 ACM WoWMoM’00-02; General Vice Chair of
IEEE PerCom’03, ACM MobiCom’00 and IEEE HiPC’00-01; Program Chair of IWDC’02, WoWMoM’98-99; TPC Vice Chair of ICPADS’02; and
as TPC member of numerous IEEE and ACM conferences.
Minyi Guo received his Ph.D. degree in information science from University of Tsukuba, Japan in 1998. From 1998 to 2000, Dr. Guo had
been a research scientist of NEC Soft, Ltd. Japan. He is currently a professor at the Department of Computer Software, The
University of Aizu, Japan. From 2001 to 2003, he was a visiting professor of Georgia State University, USA, Hong Kong Polytechnic
University, Hong Kong. Dr. Guo has served as general chair, program committee or organizing committee chair for many international
conferences, and delivered more than 20 invited talks in USA, Australia, China, and Japan. He is the editor-in-chief of the
Journal of Embedded Systems. He is also in editorial board of International Journal of High Performance Computing and Networking,
Journal of Embedded Computing, Journal of Parallel and Distributed Scientific and Engineering Computing, and International
Journal of Computer and Applications.
Dr. Guo’s research interests include parallel and distributed processing, parallelizing compilers, data parallel languages,
data mining, molecular computing and software engineering. He is a member of the ACM, IEEE, IEEE Computer Society, and IEICE.
He is listed in Marquis Who’s Who in Science and Engineering. 相似文献
Though air-breathing has probably evolved mainly as a response to hypoxia, it may provide an important oxygen supplement when metabolism is elevated, as for example during swimming. Due to the increased travelling distance involved when an air-breathing fish swims to and from the surface, and the increased drag when the surface is breached, it can be proposed that air-breathing results in a rise in the apparent cost of transport. In order to investigate this hypothesis, it is necessary to use a fish that is able to swim equally well with and without access to air. The striped catfish Pangasianodon hypophthalmus has been shown to have a sufficiently high capacity for aquatic oxygen uptake in normoxia, to allow for such a comparison. Here, we measured the partitioning of oxygen uptake ($ \dot{M}{\text{O}}_{2} $) during swimming and recovery, and calculated the apparent cost of transport with and without access to air, under normoxic conditions. Aerial $ \dot{M}{\text{O}}_{2} $ constituted 25–40 % of the total $ \dot{M}{\text{O}}_{2} $ during swimming and less than 15 % during recovery. The net cost of transport was 25 % lower in fish that did not air-breathe compared to fish that did, showing that the cost of surfacing can be substantial. This is the first study to measure partitioning in an air-breathing fish during swimming at velocities close to the critical swimming speed. 相似文献
Insect protein, used for in vitro culture media for entomopathogenic nematode, produces nematodes of high quality. However, the time-consuming culture and poor purity of nematodes hinder the commercial application of insect protein media. We show that hydrolyzed insect protein improves nematode purity in in vitro culture. The results revealed that nematode purity was increased by more than 90 %, and the culture period was reduced by 6 days. Estimated economic efficiency of using hydrolyzed insect protein medium was increased by 44.25 % over that obtained with non-hydrolyzed insect medium. 相似文献
Pulmonary lymphangioleiomyomatosis (LAM) is a rare, low-grade neoplasm affecting almost exclusively women of childbearing age. LAM belongs to the family of perivascular epithelioid cell tumors, characterized by spindle and epithelioid cells with smooth muscle and melanocytic differentiation. LAM cells infiltrate the lungs, producing multiple, bilateral lesions rich in lymphatic channels and forming cysts, leading to respiratory insufficiency. Here we used antibodies against four lymphatic endothelial markers—podoplanin (detected by D2-40), prospero homeobox 1 (PROX1), vascular endothelial growth factor receptor 3 (VEGFR-3), and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1)—to determine whether LAM cells show lymphatic differentiation. Twelve of 12 diagnostic biopsy specimens (early-stage LAM) and 19 of 19 explants (late-stage LAM) showed immunopositivity for D2-40 in most neoplastic cells. PROX1, VEGFR-3, and LYVE1 immunoreactivity varied from scarce in the early stage to abundant in the late stage. Lymphatic endothelial, smooth muscle, and melanocytic markers were partially co-localized. These findings indicate that lymphatic endothelial differentiation is a feature of LAM and provide evidence of a previously unidentified third lineage of differentiation in this neoplasm. This study has implications for the histological diagnosis of LAM, the origin of the neoplastic cells, and potential future treatment with drugs targeting lymphangiogenesis. 相似文献