Geometry of Scour Holes Associated with 90° Spur Dikes

The stable pools formed by spur dikes can be a significant factor for improving aquatic habitat in unstable degraded streams. Prediction of the volume and geometry of the scour hole associated with a spur dike yields information that is valuable for assessing the potential benefit to the aquatic habitat. Volumes of the scour hole in the vicinity of model spur dikes were measured in a laboratory flume under clear-water overtopping flows. Spur dike length, flow depth, and shear velocity ratio were varied in the experiments and found to significantly influence the volume of the scour hole. For overtopping flows, the ratio of the flow depth to the spur dike height was found to be an important control on the geometry of the resulting scour hole. At higher flow depth to spur dike height ratios, the location of the maximum depth of scour changed from the upstream point of the dike toward the channel bank and caused a secondary scour zone to form downstream of the spur dike. A preliminary technique is proposed to predict the volume of scour for spur dikes perpendicular to the bank.     

The plastid genome of the cryptophyte alga, Guillardia theta: complete sequence and conserved synteny groups confirm its common ancestry with red algae

Previously, we have purified and characterized DNA helicase III from the yeast Saccharomyces cerevisiae [Shimizu, K. and Sugino, A. (1993) J. Biol. Chem. 268, 9578-9584]. Here, we have further characterized DNA helicase III activity. It was found that the combined action of the helicase III, yeast DNA topoisomerase I (yTop I), and yeast RPA protein on a covalently closed, circular DNA generates a highly underwound DNA species that has been called form I* or form U. Furthermore, these underwound structures can be accessed by yeast DNA polymerase I (alpha)-primase to initiate DNA synthesis. These reactions mimic in vivo initiation of chromosomal DNA replication. In order to clone the gene encoding DNA helicase III, a partial amino acid sequence of the purified DNA helicase III polypeptide was determined. Using a mix oligonucleotides synthesized based on the amino acid sequence of the helicase, we cloned the gene encoding the helicase III and found it to be identical to YER176W (HEL1) on chromosome V. The amino acid sequence predicted from the nucleotide sequence of the gene has conserved DNA helicase domains that are highly homologous to those of DNA helicases required for DNA replication. However, complete deletion of the gene from the chromosome did not result in any growth defect, suggesting that the gene product is not required for DNA synthesis or that it is functionally substituted by other helicase(s). Furthermore, the deletion strain does not exhibit sensitivity to any DNA-damaging reagents, although it is hypersensitive to calcofluor white, hygromycin, and papulacandin.     

Thermal management of power electronics modules packaged by a stacked-plate technique

The research presented in this paper is part of a multidisciplinary research program of the Center for Power Electronics Systems at Virginia Tech. The program supported by the Office of Naval Research focuses on the development of innovative technologies for packaging power electronics building blocks. The primary objective of this research is to improve package performance and reliability through thermal management, i.e., reducing device temperatures for a given power level. The task of thermal management involves considering trade-offs in the electrical design, package layout and geometry, materials selection and processing, manufacturing feasibility, and production cost. Based on the electrical design of a simple building block, samples of packaged modules, rated at 600 V and 3.3 kW, were fabricated using a stacked-plate technique, termed metal posts interconnected parallel plate structure (MPIPPS). The MPIPPS technique allows the power devices to be interconnected between two direct-bond copper substrates via the use of metal posts. Thermal modeling results on the MPIPPS packaged modules indicate that the new packaging technique offers a superior thermal management means for packaging power electronics modules.     

Purification of pregastric lipases of caprine origin

Pregastric lipases from kid (KPGL) and goat (GPGL) were purified from the commercial extracts by different chromatographic procedures. The total recovery of activity for both purification methods was ca. 10%, and the specific activities of KPGL and GPGL were 533 and 546 U/mg, respectively, at pH 6.5, 35°C for tributyrylglycerol (TBG) as substrate in a casein/lecithin emulsion. The purification factors were 130- and 76-fold for the goat and kid lipases, respectively. The purified lipases from kid and goat showed the same 50 kDa protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an identical sequence for the first 11 amino acids. The optimal pH for the lipases was within the pH range 6–7, with maximal activity at pH 6.5. The stability of the purified lipases was decreased dramatically at pH>6.5, but was enhanced by the addition of albumin. Presented at the AOCS 88th Annual Meeting & Expo, May 11–14, 1997, Seattle, Washington.     

TP53 in Acute Myeloid Leukemia: Molecular Aspects and Patterns of Mutation

Mutation of the tumor suppressor gene, TP53, is associated with abysmal survival outcomes in acute myeloid leukemia (AML). Although it is the most commonly mutated gene in cancer, its occurrence is observed in only 5–10% of de novo AML, and in 30% of therapy related AML (t-AML). TP53 mutation serves as a prognostic marker of poor response to standard-of-care chemotherapy, particularly in t-AML and AML with complex cytogenetics. In light of a poor response to traditional chemotherapy and only a modest improvement in outcome with hypomethylation-based interventions, allogenic stem cell transplant is routinely recommended in these cases, albeit with a response that is often short lived. Despite being frequently mutated across the cancer spectrum, progress and enthusiasm for the development of p53 targeted therapeutic interventions is lacking and to date there is no approved drug that mitigates the effects of TP53 mutation. There is a mounting body of evidence indicating that p53 mutants differ in functionality and form from typical AML cases and subsequently display inconsistent responses to therapy at the cellular level. Understanding this pathobiological activity is imperative to the development of effective therapeutic strategies. This review aims to provide a comprehensive understanding of the effects of TP53 on the hematopoietic system, to describe its varying degree of functionality in tumor suppression, and to illustrate the need for the adoption of personalized therapeutic strategies to target distinct classes of the p53 mutation in AML management.     

Role of paired basic residues in the expression of active recombinant galactosyltransferases from the bacterial pathogen Neisseria meningitidis

The lgtB gene encoding a beta-1,4-galactosyltransferase gene and the lgtC gene encoding an alpha-1,4-galactosyltransferase from the bacterial pathogen Neisseria meningitidis were cloned into an expression vector and overexpressed in Escherichia coli. Both genes expressed very well, but problems with C-terminal proteolysis were encountered with both proteins. The lgtC protein was initially isolated from extracts of recombinant E.coli as a truncated species that retained enzymatic activity, and was subsequently shown by mass spectrometry to be 19 residues shorter than the expected protein. A specific set of engineered C-terminal deletions was constructed to investigate their effect on the expression of lgtC. As many as 28 residues could be deleted with little effect on activity, and with the concomitant improvement of the overall expression up to fivefold over the full length protein. The lgtB protein was also proteolysed in extracts of normal E.coli strains into enzymatically inactive fragments lacking 28 or 41 C-terminal residues. This degradation could be prevented by expression in an ompT protease deficient strain of E.coli. The full length lgtB protein was not stable in soluble protein extracts from all recombinant strains, however a stable enzyme preparation could be achieved with the membrane fraction from cells of the ompT deficient strain expressing lgtB. Specific deletions of lgtB were also constructed, and 15 residues could be removed without loss of enzyme activity and also with the concomitant improvement of the overall expression up to twofold over the full length protein. Longer deletions produced protein but activity could not be detected in these recombinant strains. Examination of the glycosyltransferase sequences from a wide range of bacteria showed their C-terminal segments of approximately 50 amino acids frequently contained paired basic residues. Engineering of these segments may therefore be required as a general practice to produce these enzymes for use in the large scale chemi-enzymatic synthesis of carbohydrate-based therapeutics.      

A stable nonconforming quadrilateral finite element method for the stationary Stokes and Navier–Stokes equations

Recently, Douglas et al. [4] introduced a new, low-order, nonconforming rectangular element for scalar elliptic equations. Here, we apply this element in the approximation of each component of the velocity in the stationary Stokes and Navier–Stokes equations, along with a piecewise-constant element for the pressure. We obtain a stable element in both cases for which optimal error estimates for the approximation of both the velocity and pressure in L ² can be established, as well as one in a broken H ¹-norm for the velocity. Received: January 1999 / Accepted: April 1999     

Agent-Based Systems for Intelligent Manufacturing: A State-of-the-Art Survey

Agent technology has been considered as an important approach for developing distributed intelligent manufacturing systems. A number of researchers have attempted to apply agent technology to manufacturing enterprise integration, supply chain management, manufacturing planning, scheduling and control, materials handling, and holonic manufacturing systems. This paper gives a brief survey of some related projects in this area, and discusses some key issues in developing agent-based manufacturing systems such as agent technology for enterprise integration and supply chain management, agent encapsulation, system architectures, dynamic system reconfiguration, learning, design and manufacturability assessments, distributed dynamic scheduling, integration of planning and scheduling, concurrent scheduling and execution, factory control structures, potential tools and standards for developing agent-based manufacturing systems. An extensive annotated bibliography is provided.     

Forced sexual intercourse and associated health-risk behaviors among female college students in the United States.

This study analyzed data from the 1995 National College Health Risk Behavior Survey (NCHRBS) to assess the prevalence of lifetime rape among female college students and to examine the association between rape and health-risk behaviors. The NCHRBS used a mail questionnaire to assess health-risk behaviors among a nationally representative sample of undergraduate students. Twenty percent of female students reported ever having been forced to have sexual intercourse, most often during adolescence. When analyses controlled for demographic characteristics, female students who had ever been raped were significantly more likely than those who had not to report a wide range of health-risk behaviors. These results highlight a need to improve rape prevention and treatment programs for female adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A cost-based method for comparing alternative refrigerants applied to R-22 systems: Remplacement du R22: méthode de comparaison des frigorigènes candidats

This paper describes the development and application of a general purpose method for comparing alternative refrigerants. The method utilizes a single performance index based upon minimum cost for a simplified system operating with a given cooling capacity and efficiency. The cost-based method is an improvement over other methods for evaluating refrigerants in that it more appropriately considers the influence of both thermodynamic and transport properties on refrigerant choice and it allows consideration of additional costs associated with some replacements (e.g. safety features for flammable refrigerants). A computer model based upon this method was used to evaluate the performance of several leading R-22 replacement candidates for window air conditioners. Primarily, the cost differences between alternative refrigerants are associated with the heat exchangers and the refrigerant/oil requirements. The cost differences associated with different compressor displacement requirements were found to have a minor influence on overall cost differences. For the optimized systems, all of the alternatives had system costs that were within about 4% of those for R-22. Further, the differences between most of the alternative refrigerants were smaller than the uncertainties in the analysis.