Spinosyns, a novel class of insect active macrolides produced by Saccharopolyspora spinosa, are used for insect control in a number of commercial crops. Recently, a new class of spinosyns was ...discovered from S. pogona NRRL 30141. The butenyl-spinosyns, also called pogonins, are very similar to spinosyns, differing in the length of the side chain at C-21 and in the variety of novel minor factors. The butenyl-spinosyn biosynthetic genes (bus) were cloned on four cosmids covering a contiguous 110-kb region of the NRRL 30141 chromosome. Their function in butenyl-spinosyn biosynthesis was confirmed by a loss-of-function deletion, and subsequent complementation by cloned genes. The coding sequences of the butenyl-spinosyn biosynthetic genes and the spinosyn biosynthetic genes from S. spinosa were highly conserved. In particular, the PKS-coding genes from S. spinosa and S. pogona have 91-94% nucleic acid identity, with one notable exception. The butenyl-spinosyn gene sequence codes for one additional PKS module, which is responsible for the additional two carbons in the C-21 tail. The DNA sequence of spinosyn genes in this region suggested that the S. spinosa spnA gene could have been the result of an in-frame deletion of the S. pogona busA gene. Therefore, the butenyl-spinosyn genes represent the putative parental gene structure that was naturally engineered by deletion to create the spinosyn genes.
Three-dimensional structures are now known within most protein families and it is likely, when searching a sequence database, that one will identify a homolog of known structure. The goal of Entrez's ...3D-structure database is to make structure information and the functional annotation it can provide easily accessible to molecular biologists. To this end, Entrez's search engine provides several powerful features: (i) links between databases, for example between a protein's sequence and structure; (ii) pre-computed sequence and structure neighbors; and (iii) structure and sequence/structure alignment visualization. Here, we focus on a new feature of Entrez's Molecular Modeling Database (MMDB): Graphical summaries of the biological annotation available for each 3D structure, based on the results of automated comparative analysis. MMDB is available at: http://www.ncbi.nlm.nih.gov/Entrez/structure.html.
Review of Particle Physics
The European physical journal. C, Particles and fields,
03/1998, Letnik:
3, Številka:
1-4
Journal Article
Recenzirano
Odprti dostop
This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 1600 new measurements from 550 papers, we list, evaluate, and average measured properties of gauge ...bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http: //pdg. lbl. gov.
This study enumerated CD45hi /CD34+ and CD45hi /CD133+ human hematopoietic stem cells (HSCs) and progenitor granulocyte-macrophage colony forming cells (GM-CFCs) in blood and trochanteric and femoral ...bone marrow in 233 individuals. Stem cell frequencies were determined with multiparameter flow cytometry and using an internal control to determine the intrinsic variance of the assays. Progenitor cell frequency was determined using a standard colony assay technique. The frequency of outliers from undetermined methodological causes was highest for blood, but less than 5% for all values. The frequency of CD45hi /CD133+ cells correlated highly with the frequency of CD45hi /CD34+ cells in trochanteric and femoral bone marrow. The frequency of these HSC populations in trochanteric and femoral bone marrow rose significantly with age. In contrast, there was no significant trend of either of these cell populations with age in the blood. Trochanteric marrow progenitor GM-CFCs showed no significant trends with age, but femoral marrow GM-CFCs trended downward with age, potentially because of the reported conversion of red marrow at this site to fat with age. Hematopoietic stem and progenitor cells exhibited changes in frequencies with age that differed between blood and bone marrow. We previously reported that side population (SP) multipotential HSC, which includes the precursors of CD45hi /CD133+ and CD45hi /CD34+ , decline with age. Potentially the increases in stem cell frequencies in the intermediate compartment between SP and GM progenitor cells observed in this study represent a compensatory increase for the loss of more potent members of the HSC hierarchy.
The main
objective of the present study is to examine whether “simple” turbulence models (i.e., models requiring two partial differential equations or less for turbulent transport) are suitable for ...use under conditions of forced flow of gas at low Reynolds numbers in tubes with intense heating, leading to large variations of fluid properties and considerable modification of turbulence. Eleven representative models are considered. The ability of such models to handle such flows was assessed by means of computational simulations of the carefully designed experiments of Shehata and McEligot (IJHMT 41 (1998) 4297) at heating rates of
q
+
in≈0.0018, 0.0035 and 0.0045, yielding flows ranging from essentially turbulent to laminarized. The
resulting comparisons of computational results with experiments showed that the model by Launder and Sharma (Lett. Heat Transfer 1 (1974) 131) performed best in predicting axial wall temperature profiles. Overall, agreement between the measured velocity and temperature distributions and those calculated using the Launder–Sharma model is good, which gives confidence in the values forecast for the turbulence quantities produced. These have been used to assist in arriving at a better understanding of the influences of intense heating, and hence strong variation of fluid properties, on turbulent flow in tubes.
A fundamental experimental study of buoyancy-aided and buoyancy-opposed turbulent flow and heat transfer to air in a vertical plane passage is reported. One wall was heated uniformly and the opposite ...one was unheated. Although the dominant mechanism for heat removal from the heated wall was convection, there was also some radiative heat transfer to the unheated wall. The heat received by thermal radiation was mainly removed from that wall by convection to the air flowing over it within the passage. Such a configuration has received little attention in earlier work on buoyancy-influenced flow in vertical passages. Detailed measurements of temperature were made on both walls and local values of convective heat transfer coefficient were determined on the heated surface taking careful account of the thermal radiation from it to the unheated wall and heat losses to the surroundings. A range of experimental conditions was covered over which the influence of buoyancy on the flow was systematically varied by adjusting the heat input and the mass flow rate. The mode of heat transfer ranged from forced convection with negligible influence of buoyancy to mixed convection with very strong influences of buoyancy. Profiles of velocity, turbulence intensity, turbulent shear stress and turbulence production were obtained from flow measurements made using a two-component laser Doppler Anemometer system. From these results a clear picture was arrived at of the mechanism by which the effectiveness of heat transfer was modified by the distortion of the mean flow due to the influence of buoyancy and the effect that this had on turbulence production and turbulent diffusion of heat.
Abstract
Computational simulations of turbulent mixed convection heat transfer experiments using carbon dioxide at supercritical pressure have been performed by solving the Reynolds averaged ...transport equations using an elliptic formulation. A number of two-equation low Reynolds number turbulence models have been used and the results have been compared directly with the experimental data. It has been shown that most of the models were to some extent able to reproduce the effects of the very strong influences of buoyancy on heat transfer in these experiments. However, the performance of the models varied significantly from one to another in terms of the predicted onset of such effects.
This article considers the claim in the government's White Paper, Justice for All, to put victims and witnesses at the heart of the criminal justice system and argues that there is an unresolved ...tension within the paper between instrumentalist crime control concerns and intrinsic concerns for the rights of victims and witnesses. It is argued that many of the proposals now contained in the latest Criminal Justice Bill are so preoccupied with rebalancing the system away from offenders that they risk doing injustice to defendants with little tangible benefit to victims and witnesses in terms of rights and remedies.
PDF
