Proteus: A reconfigurable computational network for computer vision

The Proteus architecture is a highly parallel, multiple instruction, multiple data machine (MIMD) optimized for large granularity tasks such as machine vision and image processing. The system can achieve 20 gigaflops (80 gigaflops peak). It accepts data via multiple serial links at a rate of up to 640 MB/S. The system employs a hierarchical reconfigurable interconnection network with the highest level being a circuit-switchedenhanced hypercube, serial interconnection network for internal data transfers. The system is designed to use 256 to 1024 RISC processors. The processors use 1-MB externalread/write allocating caches for reduced multiprocessor contention. The system detects, locates, and replaces faulty subsystems using redundant hardware to facilitatefault tolerance. The parallelism is directly controllable through an advanced software system for partitioning, scheduling, and development. System software includes a translator for the INSIGHT language, a parallel debugger, lowand high-level simulators, and a message-passing system for all control needs. Image-processing application software includes a variety of point operators, neighborhood operators, convolution, and the mathematical morphology operations of binary and gray-scale dilation, erosion, opening, and closing.     

Analysis of hydrolytic products from choline-labeled host cell phospholipids during growth of Rickettsia prowazekii

A phospholipase activity has been associated with the interaction of Rickettsia prowazekii with the surface of erythrocytes and competent host cells as well as during the growth of the rickettsiae within their host cells. Both fatty acid and lysophosphatides have been found in the interaction of rickettsiae with the surface of eucaryotic cells; this finding provided strong evidence for the activity of a phospholipase A. However, fatty acids, but not lysophosphatides, were found during the growth of rickettsiae within cells in which the phospholipids had been radiolabeled with oleic acid; this observation left the type of phospholipase activity in doubt. In this study, the water-soluble components of phospholipid hydrolysis by phospholipase A plus lysophospholipase and phospholipase C were determined following the growth of rickettsiae in host cells in which the phospholipids had been radiolabeled with choline. In infected cells relative to mock-infected cells, there was a loss of phosphatidylcholine with a corresponding increase not in lysophosphatidylcholine but in the water-soluble components. There was a large increase in glycerylphosphorylcholine (185%) and a smaller increase in phosphorylcholine (16%). These results indicate that both phospholipase A activity (plus a lysophospholipase activity) and phospholipase C were increased during infection by R. prowazekii and that the former was the predominant activity.     

Directed evolution of a biterminal bacterial display scaffold enhances the display of diverse peptides

Bacterial cell-surface display systems coupled with quantitative screening methods offer the potential to expand protein engineering capabilities. To more fully exploit this potential, a unique bacterial surface display scaffold was engineered to display peptides more efficiently from the surface exposed C- and N-termini of a circularly permuted outer membrane protein. Using directed evolution, efficient membrane localization of a circularly permuted OmpX (CPX) display scaffold was rescued, thereby improving the presentation of diverse passenger peptides on the cell surface. Random and targeted mutagenesis directed towards linkers joining the native N- and C-termini of OmpX coupled with screening by FACS yielded an enhanced CPX (eCPX) variant which localized to the outer membrane as efficiently as the non-permuted parent. Interestingly, enhancing substitutions coincided with a C-terminal motif conserved in outer membrane proteins. Surface localization of various passenger peptides and mini-proteins was expedited using eCPX relative to that achieved with the parent scaffold. The new variant also permitted simultaneous display and labeling of distinct peptides on structurally adjacent C- and N-termini, thus enabling display level normalization during library screening and the display of bidentate or dimeric peptides. Consequently, the evolved scaffold, eCPX, expands the range of applications for bacterial display. Finally, this approach provides a route to improve the performance of cell-surface display vectors for protein engineering and design.     

Monitoring a flood event in a densely instrumented catchment, the Upper Eden, Cumbria, UK

Multi‐day rainfall events appear to be an important cause of recent flooding in the UK. Hydrological data from an extensive, nested hydrometric network in the unregulated, predominantly rural Upper Eden catchment in northern England are presented for one such flood event. These highlight antecedent catchment conditions and the propagation of the multi‐day flood event during February 2004. An assessment of flood response is provided over varying scales and land use between the upland Gais Gill catchment (1.1 km²) and the larger Upper Eden catchment (616 km²). Large spatial variations in rainfall totals are identified from a dense raingauge network during the flood event and are principally related to catchment elevation. High cumulative rainfall totals for the 6‐day event, particularly at upland sites appear to be the exceptional feature of the flood event with return periods in the order of 100 years at some upland gauges. Resultant patterns of flood attenuation and translation are quantified in different areas of the catchment, highlighting the flashy response of the headwater catchments and the attenuated downstream response in the lowland environment. The study forms part of the national Catchment Hydrology And Sustainable Management (CHASM) programme.     

Antibody affinity maturation using bacterial surface display

A quantitative system for screening combinatorial single-chain Fv (scFv) antibody libraries was developed utilizing surface display on Escherichia coli and fluorescence-activated cell sorting (FACS). This system was employed to isolate clones with high-affinity to a fluorescently-labeled hapten from libraries constructed by randomizing heavy and light-chain residues in the anti-digoxin 26-10 derived antibody, scFv(dig). The use of flow cytometry enabled the detection of rare library members directly in heterogeneous populations and the optimization of selection conditions prior to sorting. A heavy-chain mutant having wild-type affinity (KD = 0.91+/-0.22 nM) and an expected representation frequency of less than 1 x 10(6), was selected to homogeneity after three rounds utilizing increasingly stringent selection conditions. The isolated clone possessed two distinct point mutations relative to the wild-type DNA sequence, yet still coded for the wild-type amino acid sequence, suggesting that the wild-type residues may be optimal at the randomized positions. An affinity improved clone (KD = 0.30+/-0.05 nM), having a dissociation constant approximately threefold lower than the wild-type antibody, was isolated from a smaller light-chain library in a single sorting step. Flow cytometry was shown to be a simple and rapid method for the determination of the relative hapten dissociation rate constants of selected clones without requiring subcloning. The relative rate constants estimated by FACS were confirmed by producing the scFv antibodies in soluble form and measuring hapten binding kinetics by surface plasmon resonance (SPR). These results demonstrate that E.coli surface display, coupled with quantitative selection and analysis using FACS, has the potential to become a powerful tool for rapid isolation and characterization of desirable mutants from large polypeptide libraries.      

Goal structures and teachers' sense of efficacy: Their relation and association to teaching experience and academic level.

Goal structures reflect the motivational beliefs promoted by the prevailing instructional policies and procedures within an academic setting. Teachers' sense of efficacy refers to individuals' judgments or beliefs regarding their ability to accomplish critical instructional tasks. The relation between these constructs and differences on the basis of teaching experience and academic level were investigated. Teachers (N = 1,024) completed a self-report instrument via the Internet. Results indicated that teachers' sense of efficacy could be used to explain the classroom mastery goal structure they reported. Also, some aspects of teachers' sense of efficacy were greater for those with more teaching experience, whereas differences in goal structures were associated with academic level. Findings are discussed with regard to their implications for both theory and teacher training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plasminogen deficiency causes severe thrombosis but is compatible with development and reproduction

Plasminogen (Plg)-deficient mice were generated to define the physiological roles of this key fibrinolytic protein and its proteolytic derivatives, plasmin and angiostatin, in development, hemostasis, and reproduction. Plg-/- mice complete embryonic development, survive to adulthood, and are fertile. There is no evidence of fetal loss of Plg-/- mice based on the Mendelian pattern of transmission of the mutant Plg allele. Furthermore, embryonic development continues to term in the absence of endogenous, sibling-derived, or maternal Plg. However, Plg-/- mice are predisposed to severe thrombosis, and young animals developed multiple spontaneous thrombotic lesions in liver, stomach, colon, rectum, lung, pancreas, and other tissues. Fibrin deposition in the liver was a uniform finding in 5- to 21-week-old mice, and ulcerated lesions in the gastrointestinal tract and rectal tissue were common. A remarkable finding, considering the well-established linkage between plasmin and the proteolytic activation of plasminogen activators, was that the level of active urokinase-type plasminogen activator in urine was unaffected in Plg-/- mice. Therefore, Plg plays a pivotal role in fibrinolysis and hemostasis but is not essential for urokinase proenzyme activation, development, or growth to sexual maturity.     

Development of a single-shot subunit vaccine for HIV-1. 2. Defining optimal autoboost characteristics to maximize the humoral immune response

The design of a single-shot subunit vaccine for HIV-1 with polylactic-coglycolic acid (PLGA) sustained-release technology to effect an autoboost of antigen (MN gp120) at a given time after the primary immunization requires in-depth knowledge about the timing, the duration, and the need for coadjuvant in the autoboost. These questions cannot be answered unambiguously with PLGA microspheres, so we have conducted studies using Alzet minipumps to release antigen at prescribed times to mimic a PLGA autoboost. The results show that a discrete autoboost is preferred over continuous release of antigen, that the time profile of the autoboost (whether pulsatile or a 2-week continuous release) does not affect the booster immune response, and that only antigen is required in the booster immunization (a coadjuvant in the boost does not give higher titers).     

Prevention and control of tuberculosis in the 1990s

Beginning in 1984, the long-term decline in tuberculosis (TB) cases stopped, and since 1985 the number of cases has actually increased by 18%, from 22,201 new cases in 1985 to 26,283 in 1991. The change in the morbidity trend appears to be primarily due to three factors: HIV coinfection, TB occurring in persons from countries where this disease is prevalent, and deterioration of the health care infrastructure with resultant outbreaks of TB. This article presents six interventions that address major areas where action is needed. These efforts will require coordinated action by health care providers, public health departments, and other public and private organizations. Protection of all workers and patients in health care settings is one important goal of these efforts.