bluuebunny/crossref_metadata_2025 huggingface dataset:
Bohunice Simulator Data Collection Project
Authors: Cˇilli´k Ivan , Procha´ska Ja´n
Published: March 2009

The paper describes the way and results of human reliability data analysis collected as a part of the Bohunice Simulator Data Collection Project (BSDCP), which was performed by VUJE Trnava, Inc. with funding support from the U.S. DOE, National Nuclear Security Administration. The goal of the project was to create a methodology for simulator data collection and analysis to support activities in probabilistic safety assessment (PSA) and human reliability assessment for Jaslovske Bohunice nuclear power plant consisting of two sets of twin units: two VVER 440/V-230 (V1) and two VVER 440/V-213 (V2) reactors. During the project training of V-2 control room crews was performed at VUJE-Trnava simulator. The simulator training and the data collection were done in parallel. The main goal of BSDCP was to collect suitable data of human errors under simulated conditions requiring the use of symptom-based emergency operating procedures (SBEOPs). The subjects of the data collection were scenario progress time data, operator errors, and real-time technological parameters. The paper contains three main parts. The first part presents preparatory work and semi-automatic computer-based methods used to collect data and to check technological parameters in order to find hidden errors of operators, to be able to retrace the course of each scenario for purposes of further analysis, and to document the whole training process. The first part gives also an overview of collected data scope, human error taxonomy, and state classifications for SBEOP instructions coding. The second part describes analytical work undertaken to describe time distribution necessary for execution of various kinds of instructions performed by operators according to the classification for coding of SBEOP instructions. It also presents the methods used for determination of probability distribution for different operator errors. Results from the data evaluation are presented in the last part of the paper. An overview of observed human error probabilities (HEP) according to the developed taxonomy is given. HEP observed during training process were used as reference input data for HRA (Human Reliability Assesment) within existing PSAs performed by VUJE. Observing two different training seasons offered an opportunity to compare a progress achieved through the training process. This paper shows us how it is possible to make this kind of comparison in order to establish an objective measure of training quality and to determine training weaknesses. Results gained during the project-evoked interest of different NPPs (Nuclear Power Plant) in Slovak Republic to collect and process simulator data for further improvement of human factor safety, operational procedures, training process, etc.
VVER-440 Containment Thermal Hydraulic Analyses With MELCOR and CONTAIN Codes
Authors: Gromov Gregory , Lola Igor , Sholomitsky Stanislav , Gumenyuk Dmitry , Shikhabutinov Valery , Alekseev Yury , Wagner K. C. , Dallman Jack
Published: March 2009

In support of the analyses for the Rivne Nuclear Power Plant (RNPP) VVER-440/213 (Ukraine) Safety Analysis Report (SAR), detailed MELCOR and CONTAIN models of the containment were developed. The RNPP containment features a bubble condenser tower with air locks and active and passive spray systems. Code input models were developed to accurately represent the containment volumes, room interconnections, structural masses, and the engineering safety features. Although MELCOR 1.8.3 [1] was the primary tool for the SAR containment analysis, comparison calculations were performed using CONTAIN Version 1.12 [2]. Consequently, both the response of the VVER-440 containment to limiting design conditions as well as a comparison of the two codes is presented. In the context of SAR requirements, the present application was performed for design basis accidents with conservative assumptions to compare the containment temperature and pressure with design criteria. The peak containment pressure and temperature were evaluated using the most intensive release of the primary and secondary coolant into the hermetic compartments, in particular, for the large break loss of coolant accident and main steam line break. Conservative coolant release data were evaluated using the RELAP5/Mod3.2 SAR model. The selection of the accident scenario, initial and boundary conditions, and the major results are presented. The results of the analyses will be included in the design basis accident analysis chapter of the RNPP SAR.
Local Approach of Fracture in the Ductile Regime and Application to VVER Materials
Authors: Margolin B. Z. , Kostylev V. I. , Keim E. , Chaouadi R.
Published: March 2009

Within the TACIS R2.06/96 project: “Surveillance Program for VVER 1000 Reactors”, sponsored by the European Commission, the local approach of fracture has been applied in the ductile regime. Two different models were applied and compared, namely Tvergaard-Needleman-Gurson versus Prometey model. The main tasks are: • perform special Local Approach experiments on smooth and notched cylindrical specimens; • predict JR-curve on the basis of the ductile fracture models; • compare two models of ductile fracture, namely, the Tvergaard-Needleman-Gurson model and the Prometey model. In this paper, the Tvergaard-Needleman-Gurson and Prometey models are briefly described. The parameters of both models were calibrated by using experimental data obtained on tensile specimens. While only smooth tensile specimens are used to calibrate the Tvergaard-Needleman-Gurson model, notched tensile in addition to smooth tensile specimens are used to calibrate the Prometey model. In the latter, standard smooth tensile specimens are used to determine the mechanical properties (the yield stress σy, the ultimate stress σu, the ultimate elongation δu, the area reduction Z) and notched cylindrical specimens to determine the strain at rupture. The numerical analysis comprises essentially two steps: • Step 1: finite element simulation of the smooth tensile specimen (determination of true stress-strain curve and critical void volume fraction for the Tvergaard-Needleman-Gurson model) and simulation of the notched cylindrical specimen up to rupture (determination of stress triaxiality for the Prometey model); • Step 2: finite element simulation of the 2T CT specimen and determination of the crack resistance behaviour in the ductile regime (J-Δa curve). It is found that both models were able to correctly predict the crack resistance behaviour of the investigated materials. The numerical and the experimental results were in very good agreement. The main difference between the two models is that the required number of calibrated parameters in the Prometey model is less than in the Tvergaard-Needleman-Gurson model but additional tests on notched specimens are required for the Prometey model.
Simple Analytical U-Tube Benchmarks Appropriate for Testing of Pipe-Network Computer Codes
Authors: Kolev N. I.
Published: March 2009

Partially heated U-tube configurations are characteristic idealizations for the so called building condensers of future nuclear reactors with passive safety systems. In this paper three simple cases of natural circulation problems are analyzed and analytical solutions are generated. This solutions are recommended for validation of pipe network computer codes. As an example the procedure is demonstrated for the IVA computer code. The usefulness of the obtained solutions is demonstrated discussing the inherent safety behavior of the building condenser of the Framatome ANP SWR 1000 power plant being under development.
Post Test Calculation With CFX-4 of the OECD/CSNI International Standard Problem Nr.43
Authors: Hoehne T.
Published: March 2009

The need of experiments for validation of the computational tools to analyze the mixing of diluted slugs has been recognized in various countries. The test series performed at the UM2×4 loop test facility for the International Standard Problem ISP-43 provides a platform for experiences to be applied to the simulation of a well-defined test series. Test A was calculated with the CFD Code CFX-4.3. The results of the calculation show qualitatively good agreement with the experimental data. The structure of the flow field and the form of the propagating temperature perturbation front are well modeled by the CFD code. However, deviations occur at local positions. Comparative calculations with and without taking into account buoyancy have shown, that buoyancy effects are noticeable, but the mixing is mainly momentum controlled.
System Based Code: Principal Concept
Authors: Asada Yasuhide , Tashimo Masanori , Ueta Masahiro
Published: March 2009

This paper introduces a concept of the “System Based Code” which has initially been proposed by the authors intending to give nuclear industry a leap of progress in the system reliability, performance improvement, and cost reduction. The concept of the System Based Code intends to give a theoretical procedure to optimize the reliability of the system by administrating every related engineering requirement throughout the life of the system from design to decommissioning.
System Based Code: Basic Structure
Authors: Asada Yasuhide , Tashimo Masanori , Ueta Masahiro
Published: March 2009

This paper introduces the basic theoretical structure of the “System Based Code” which has initially been proposed by the authors intending to give nuclear industry a leap of progress in the system reliability, performance improvement and cost reduction. The System Based Code intends to give a theoretical procedure to optimize the reliability of the system by administrating every related engineering requirement throughout the life of the system: from design to decommissioning.
Developments on Implementation of WOG Risk-Informed Inservice Inspection Methodology
Authors: Boggess Cheryl L. , Kolonay John F. , Allones Luis Ulloa , Balkey Kenneth R. , Billington Anthony , Bishop Bruce A. , Haessler Richard L. , Stevenson Paul R.
Published: March 2009

The Westinghouse Owners Group (WOG) risk-informed inservice inspection (ISI) methodology has been in use for over three years as an alternative to current regulatory requirements in the development and implementation of ISI programs for nuclear plant piping systems. This paper builds upon technical papers presented at ICONE-8 and ICONE-9 that reported on the risk-informed ISI applications being developed and implemented within the U.S. and several other countries. While many applications are nearing completion around the globe, much progress has been made in extending the WOG risk-informed ISI approach to several other initiatives. This paper summarizes the results from the development and implementation of the WOG risk-informed ISI methodology in the U.S., Europe and Asia for limited Class 1 scope through full scope applications. References for associated activities in risk-informing the safety classification of pressure boundary components in support of Option 2 and redefining large break loss-of-coolant accident technical requirements as part of Option 3 in risk-informing 10CFR Part 50 are identified. The current status of program maintenance of the risk-informed living program and direct application of the methodology in modifying requirements for augmented examinations for high energy line break in break exclusion regions are summarized.
Developments on ASME Code Cases to Risk-Inform Repair/Replacement Activities in Support of Risk-Informed Regulation Initiatives
Authors: Balkey Kenneth R. , Holston William C.
Published: March 2009

ASME Code Case N-658, “Risk-Informed Safety Classification for Use in Risk-Informed Repair/Replacement Activities” and Code Case N-660, “Alternative Repair/Replacement Requirements For Items Classified In Accordance With Risk-Informed Processes” are being completed to expand the breadth of risk-informed requirements for pressure-retaining items. This initiative, which is built from prior ASME Section XI risk-informed inservice inspection developments over the past decade, has been undertaken in conjunction with U.S. risk-informed regulation efforts. The U.S. Nuclear Regulatory Commission (NRC) is working with the industry on risk informing Title 10 Code of Federal Regulations Part 50 (10CFR50). The Nuclear Regulatory Commission’s basic proposal is to allow modification of some of the special treatment requirements of 10CFR50. Their effort is proceeding via an Advanced Notice of Public Rulemaking, March 3, 2000, and an announcement of Availability of Draft Rule Wording, November 29, 2001, to add 10 CFR 50.69, “Risk-Informed Treatment of Structures, Systems and Components.” A parallel task by the Nuclear Energy Institute (NEI) to develop a guideline on how to implement the results of the rulemaking is also well underway via NEI 00-04 (Draft Revision B), “Option 2 Implementation Guideline,” May 2001. This paper summarizes the content and status of approval of the proposed ASME Code Cases, including how they relate to the above NRC and NEI efforts. Some initial results from trial application of the Code Cases will also be cited.
Radiation Induced Surface Activity Phenomenon: 1st Report — Surface Wettability on Metal Oxides
Authors: Imai Yasuyuki , Koga Tatsuya , Takamasa Tomoji , Okamoto Koji , Uematsu Susumu
Published: March 2009

Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. We investigated surface wettability using metal oxides irradiated by gamma rays in room condition. Contact angle, an indicator of macroscopic wettability, was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on oxide metal pieces of titanium, zircalloy No. 4, SUS-304 and copper improved significantly by Radiation Induced Surface Activity (RISA) phenomenon. Highly hydrophilic conditions on the test pieces were achieved after 500 kGy irradiation of 60Co gamma ray.
Study on Counter-Current Flow Rewetting in Narrow-Annular Flow Passages
Authors: Sakamoto Naoki , Hironobu Asanuma , Yosihiro Shimamura , Masanori Tukudo , Koizumi Yasuo , Ohtake Hiroyasu
Published: March 2009

Rewetting of a hot wall by gravitational liquid penetration into a narrow-annular space was experimentally examined. Experiments were conducted by using R-113 liquid to simulate high-pressure and high-temperature water. When the gap clearance was 5 mm, liquid fell down into the annular space and accumulated in the lower portion of the flow channel. Then, the hot wall was quenched from the bottom by the accumulated liquid. When the gap clearance was less than 1mm, liquid did not penetrate into the space substantially because of the counter-current flow limiting at the top entrance. Therefore, the hot wall was cooled down very slowly and quenching was not perceived distinctly. When the gap clearance was 2 mm, mixed phenomena of the gap clearance 5 mm and 1 mm were observed. The heat transfer characteristics during quenching were quite similar to those in pool boiling. However, the film boiling heat flux and the peak (critical) heat flux tended to decrease with the gap spacing. The rewetting velocity became slow as the gap spacing became narrow. The liquid penetration limiting with the gap spacing might be reflected on this trend.
Non-Linear Stress Analysis of Threaded Connection With High Strength Ratio Materials
Authors: Khair K. R. , Singh P. N.
Published: March 2009

When the relative strength ratio of nut-to-bolt thread is high, the weaker of the two threads will deflect under the relatively stiff action of the other. The rules of the ASME B1.1-1989 provide general design rules for designing non-critical threaded joints. Most threaded joint designs are based on these rules. In most cases, the strengths of the stud and the nut are about the same. This paper addresses plastic deformation and strain in the threaded part of a component (stud) whose strength is about 7 times more than the mating threads. An axisymmetric finite element analysis was performed using nonlinear material properties and nonlinear contact elements between the surfaces of the threads. The results were used to calculate the collapse load for the thread following the rules of Appendix F of the ASME B&PV. It was found that the collapse (maximum allowed) load calculated using this nonlinear finite element approach and Appendix F of ASME code is 50% higher than the load calculated using the conventional elastic methods given in the ASME code rules would be acceptable.
Numerical Investigation of Bifurcation in Water Column Oscillator
Authors: Kawamata K. , Morimoto Y. , Okamoto K. , Madarame H.
Published: March 2009

Behavior of a water column oscillator with a cover gas system was studied experimentally and analytically. One of the free water surfaces was sealed with the cover gas, while the other was open to the atmosphere. The cover gas was supplied with a constant rate, and it was ejected through a valve when the water level reached a certain point. As soon as the level reached another point, the valve closed and the cover gas quantity increased again. In the experiment, a bifurcation-like phenomenon was observed; the valve closed period usually had single value, while it took two values under certain conditions. In order to examine the cause of this bifurcation-like phenomenon, a numerical analysis model was developed which described the system behavior precisely. The analytical result revealed that the bifurcation-like phenomenon was not bifurcation. Very small noise superimposed on the singular characteristic of the system was found to cause the two duration values under the conditions; the duration changed abruptly by an uncontrollable slight variation of the system conditions. It is likely to be confused with bifurcation by observers who could not perceive the uncontrollable noise.
A Moving Subgrid Model for Simulation of Reflood Heat Transfer
Authors: Frepoli Cesare , Mahaffy John H. , Hochreiter Lawrence E.
Published: March 2009

In the quench front and froth region the thermal-hydraulic parameters experience a sharp axial variation. The heat transfer regime changes from single-phase liquid, to nucleate boiling, to transition boiling and finally to film boiling in a small axial distance. One of the major limitations of all the current best-estimate codes is that a relatively coarse is used to solve the complex fluid flow and heat transfer problem in proximity of the quench front of a reactor core during reflood. The use of a fine axial mesh for the entire core becomes prohibitive because of the large computational costs involved. Moreover as the mesh size decreases, the standard numerical methods based on a semi-implicit scheme, tend to become unstable. A sub-grid model was developed to resolve the complex thermal-hydraulic problem at the quench front and froth region. The model is a Fine Hydraulic Moving Grid that overlies a coarse Eulerian mesh in the proximity of the quench front and froth region. The fine mesh moves in the core and follows the quench front as it advances in the core while the rods cool and quench. The Fine Hydraulic Moving Grid (FHMG) software package was developed and implemented into the COBRA-TF computer code. This paper presents the model and discusses preliminary results obtained with the COBRA-TF/FHMG computer code.
Westinghouse AP1000 Advanced Plant Simplification Results, Measures, and Benefits
Authors: Paulson C. K.
Published: March 2009

A clear distinction between advanced plants, such as the Westinghouse AP1000 and AP600, and evolutionary plants is the policy in the latter to use current systems’ and buildings’ configurations. This approach does not promote simplification or streamlining, especially in the mechanical systems of the plant. The most significant simplification in evolutionary designs has arguably been in the plant electronics where compact digital components and multiplexing have led to improvements, especially in the areas of information display, installation, and testing. The Westinghouse advanced, passive plants take a different approach. Their design engineers presume that if regulatory requirements can be satisfied by using passive systems, then active plant systems that are only designed to meet plant control functions and not burdened with meeting a safety pedigree can be implemented. This separation of safety and control allows the plant designer to focus on systems’ optimization and reliability by reducing complexity and its associated cost. This design policy has led Westinghouse to the AP600 and AP1000 plant configurations, both of which incorporate significant improvements in areas of plant simplification and enhanced safety.
The Challenge of Finding a Cure for HIV Infection
Authors: Richman Douglas D. , Margolis David M. , Delaney Martin , Greene Warner C. , Hazuda Daria , Pomerantz Roger J.
Published: March 2009

Although combination therapy for HIV infection represents a triumph for modern medicine, chronic suppressive therapy is required to contain persistent infection in reservoirs such as latently infected CD4
+
lymphocytes and cells of the macrophage-monocyte lineage. Despite its success, chronic suppressive therapy is limited by its cost, the requirement of lifelong adherence, and the unknown effects of long-term treatment. This review discusses our current understanding of suppressive antiretroviral therapy, the latent viral reservoir, and the needs for and challenges of attacking this reservoir to achieve a cure.
Brightly Fluorescent Single-Walled Carbon Nanotubes via an Oxygen-Excluding Surfactant Organization
Authors: Ju Sang-Yong , Kopcha William P. , Papadimitrakopoulos Fotios
Published: March 2009

Attaining high photoluminescence quantum yields for single-walled carbon nanotubes (SWNTs) in order to broaden their optoelectronics and sensing applications has been a challenging task. Among various nonradiative pathways, sidewall chemisorption of oxygen provides a known defect for exciton quenching through nanotube hole doping. We found that an aliphatic (dodecyl) analog of flavin mononucleotide, FC12, leads to high dispersion of SWNTs, which tend to aggregate into bundles. Unlike other surfactants, the surface organization of FC12 is sufficiently tight to exclude oxygen from the SWNT surface, which led to quantum yields as high as 20%. Toluene-dispersed, FC12-wrapped nanotubes exhibited an absorption spectrum with ultrasharp peaks (widths of 12 to 25 milli–electron volts) devoid of the characteristic background absorption of most nanotube dispersions.
Probing the Angular Momentum Character of the Valence Orbitals of Free Sodium Nanoclusters
Authors: Bartels C. , Hock C. , Huwer J. , Kuhnen R. , Schwöbel J. , von Issendorff B.
Published: March 2009

Although many properties of polyatomic metal clusters have been rationalized by an electron shell model resembling that used for free atoms, it remained unclear how reliable this analogy is with respect to the angular momentum eigenstate character of the electronic wave functions. We studied free size-selected negatively charged clusters of sodium atoms (Na

n

–
) of approximately spherical shape (
n
= 19, 40, 55, 58, 147) by angle-resolved photoelectron spectroscopy over a broad range of photon energies (1.5 to 5 electron volts). Highly anisotropic, state- and energy-dependent angular distributions emerged for all sizes. Well-defined classes of energy dependence related to the approximate angular momenta of the bound-state orbitals indicate that the overall character of the valence electron wave functions is not appreciably influenced by the interaction with the ion background. The measured distributions nevertheless deviate strongly from the predictions of single-electron models, hinting at a distinct role of correlated multielectron effects in the photoemission process.
Portrait of the Artist
Authors: Pederson Thoru
Published: March 2009

The Art and Politics of Science
.
By Harold Varmus
. Norton, New York, 2009. 337 pp. $24.95, C$27.50. ISBN 9780393061284.
Selection of H5N1 Influenza Virus PB2 during Replication in Humans
Authors: Le Quynh Mai , Sakai-Tagawa Yuko , Ozawa Makoto , Ito Mustumi , Kawaoka Yoshihiro
Published: March 2009

Highly pathogenic H5N1 influenza viruses continue to cause concern, even though currently circulating strains are not efficiently transmitted among humans. For efficient transmission, amino acid changes in viral proteins may be required. Here, we examined the amino acids at positions 627 and 701 of the PB2 protein. A direct analysis of the viral RNAs of H5N1 viruses in patients revealed that these amino acids contribute to efficient virus propagation in the human upper respiratory tract. Viruses grown in culture or eggs did not always reflect those in patients. These results emphasize the importance of the direct analysis of original specimens.
Simulating Henipavirus Multicycle Replication in a Screening Assay Leads to Identification of a Promising Candidate for Therapy
Authors: Porotto Matteo , Orefice Gianmarco , Yokoyama Christine C. , Mungall Bruce A. , Realubit Ronald , Sganga Michael L. , Aljofan Mohamad , Whitt Michael , Glickman Fraser , Moscona Anne
Published: March 2009

Nipah (NiV) and Hendra (HeV) viruses are emerging zoonotic paramyxoviruses that cause encephalitis in humans, with fatality rates of up to 75%. We designed a new high-throughput screening (HTS) assay for inhibitors of infection based on envelope glycoprotein pseudotypes. The assay simulates multicycle replication and thus identifies inhibitors that target several stages of the viral life cycle, but it still can be carried out under biosafety level 2 (BSL-2) conditions. These features permit a screen for antivirals for emerging viruses and select agents that otherwise would require BSL-4 HTS facilities. The screening of a small compound library identified several effective molecules, including the well-known compound chloroquine, as highly active inhibitors of pseudotyped virus infection. Chloroquine inhibited infection with live HeV and NiV at a concentration of 1 μM in vitro (50% inhibitory concentration, 2 μM), which is less than the plasma concentrations present in humans receiving chloroquine treatment for malaria. The mechanism for chloroquine's antiviral action likely is the inhibition of cathepsin L, a cellular enzyme that is essential for the processing of the viral fusion glycoprotein and the maturation of newly budding virions. Without this processing step, virions are not infectious. The identification of a compound that inhibits a known cellular target that is important for viral maturation but that had not previously been shown to have antiviral activity for henipaviruses highlights the validity of this new screening assay. Given the established safety profile and broad experience with chloroquine in humans, the results described here provide an option for treating individuals infected by these deadly viruses.
The Epstein-Barr Virus Alkaline Exonuclease BGLF5 Serves Pleiotropic Functions in Virus Replication
Authors: Feederle R. , Bannert H. , Lips H. , Müller-Lantzsch N. , Delecluse H.-J.
Published: March 2009

The Epstein-Barr virus (EBV) alkaline exonuclease BGLF5 has previously been recognized to contribute to immune evasion by downregulating production of HLA molecules during virus replication. We have constructed a BGLF5-null virus mutant to determine BGLF5's functions during EBV viral replication. Quantification of virus production in permissive 293 cells carrying a ΔBGLF5 genome identified a 17- to 21-fold reduction relative to complemented or wild-type controls. Detailed monitoring of ΔBGLF5 replication evidenced an impaired virus nucleocapsid maturation, a reduced primary egress and a 1.4-fold reduction in total viral DNA synthesis. ΔBGLF5 single-unit-length viral genomes were not only less abundant but also migrated faster than expected in gel electrophoresis. We concluded that BGLF5 pertained both to the generation and to the processing of viral linear genomes. ΔBGLF5 phenotypic traits were reminiscent of those previously identified in a mutant devoid of UL12, BGLF5's homolog in herpes simplex virus type 1, and indeed UL12 was found to partially complement the ΔBGLF5 phenotype. However, BGLF5-specific functions could also be identified; the nuclear membrane of replicating cells displayed images of reduplication and complex folding that could be completely corrected by BGLF5 but not UL12. Similar nuclear abnormalities were previously observed in cells transfected with BFLF2 and BFRF1, two viral proteins crucial for EBV nuclear egress. Interestingly, ΔBGLF5 cells produced more BFLF2 than wild-type or complemented counterparts. The present study provides an overview of BGLF5's functions that will guide future molecular studies. We anticipate that the 293/ΔBGLF5 cell line will be instrumental in such developments.
The Human Immunodeficiency Virus Type 2 Vpx Protein Usurps the CUL4A-DDB1
DCAF1
Ubiquitin Ligase To Overcome a Postentry Block in Macrophage Infection
Authors: Bergamaschi Anna , Ayinde Diana , David Annie , Le Rouzic Erwann , Morel Marina , Collin Gilles , Descamps Diane , Damond Florence , Brun-Vezinet Françoise , Nisole Sebastien , Margottin-Goguet Florence , Pancino Gianfranco , Transy Catherine
Published: March 2009

The human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) genomes encode several auxiliary proteins that have increasingly shown their importance in the virus-host relationship. One of these proteins, Vpx, is unique to the HIV-2/SIVsm lineage and is critical for viral replication in macrophages. The functional basis for this requirement, as well as the Vpx mode of action, has remained unexplained, and it is all the more enigmatic that HIV type 1 (HIV-1), which has no Vpx counterpart, can infect macrophages. Here, we underscore DCAF1 as a critical host effector of Vpx in its ability to mediate infection and long-term replication of HIV-2 in human macrophages. Vpx assembles with the CUL4A-DDB1 ubiquitin ligase through DCAF1 recruitment. Precluding Vpx present in the incoming virions from recruiting DCAF1 in target macrophages leads to a postentry block characterized by defective accumulation of HIV-2 reverse transcripts. In addition, Vpx from SIVsm functionally complements Vpx-defective HIV-2 in a DCAF1-binding-dependent manner. Altogether, our data point to a mechanism in which Vpx diverts the Cul4A-DDB1
DCAF1
ligase to inactivate an evolutionarily conserved factor, which restricts macrophage infection by HIV-2 and closely related simian viruses.
Virus-Specific Cytolytic Antibodies to Nonstructural Protein 1 of Japanese Encephalitis Virus Effect Reduction of Virus Output from Infected Cells
Authors: Krishna Venkatramana D. , Rangappa Manjuladevi , Satchidanandam Vijaya
Published: March 2009

We demonstrate the presence of nonstructural protein 1 (NS1)-specific antibodies in a significant proportion of convalescent-phase human serum samples obtained from a cohort in an area where Japanese encephalitis virus (JEV) is endemic. Sera containing antibodies to NS1 but not those with antibodies to other JEV proteins, such as envelope, brought about complement-mediated lysis of JEV-infected BHK-21 cells. Target cells infected with a recombinant poxvirus expressing JEV NS1 on the cell surface confirmed the NS1 specificity of cytolytic antibodies. Mouse anti-NS1 cytolytic sera caused a complement-dependent reduction in virus output from infected human cells, demonstrating their important role in viral control. Antibodies elicited by JEV NS1 did not cross lyse West Nile virus- or dengue virus-infected cells despite immunoprecipitating the NS1 proteins of these related flaviviruses. Additionally, JEV NS1 failed to bind complement factor H, in contrast to NS1 of West Nile virus, suggesting that the NS1 proteins of different flaviviruses have distinctly different mechanisms for interacting with the host. Our results also point to an important role for JEV NS1-specific human immune responses in protection against JE and provide a strong case for inclusion of the NS1 protein in next generation of JEV vaccines.
Mixtures of Complete andpif1- andpif2-Deficient Genotypes Are Required for Increased Potency of an Insect Nucleopolyhedrovirus
Authors: Clavijo Gabriel , Williams Trevor , Simón Oihane , Muñoz Delia , Cerutti Martine , López-Ferber Miguel , Caballero Primitivo
Published: March 2009

The insecticidal potency of a nucleopolyhedrovirus population (SfNIC) that infectsSpodoptera frugiperda(Lepidoptera) is greater than the potency of any of the component genotypes alone. Occlusion bodies (OBs) produced in mixed infections comprising the complete genotype and a deletion genotype are as pathogenic as the natural population of genotypes from the field. To test whether this increased potency was due to the deletion or to some other characteristic of the deletion variant genome, we used the SfNIC-B genome to construct a recombinant virus (SfNIC-BΔ16K) with the same 16.4-kb deletion as that observed in SfNIC-C and another recombinant (SfNIC-BΔpifs) with a deletion encompassing two adjacent genes (pif1andpif2) that are essential for transmission per os. Mixtures comprising SfNIC-B and SfNIC-BΔ16K in OB ratios that varied between 10:90 and 90:10 were injected into insects, and the progeny OBs were fed to larvae in an insecticidal potency assay. A densitometric analysis of PCR products indicated that SfNIC-B was generally more abundant than expected in mixtures based on the proportions of OBs used to produce the inocula. Mixtures derived from OB ratios of 10, 25, or 50% of SfNIC-BΔ16K and the corresponding SfNIC-B proportions showed a significant increase in potency compared to SfNIC-B alone. The results of potency assays with mixtures comprising various proportions of SfNIC-B plus SfNIC-BΔpifswere almost identical to the results observed with SfNIC-BΔ16K, indicating that deletion of thepifgene region was responsible for the increased potency observed in mixtures of SfNIC-B and each deletion recombinant virus. Subsequently, mixtures produced from OB ratios involving 10 or 90% of SfNIC-BΔ16K with the corresponding proportions of SfNIC-B were subjected to four rounds of per os transmission in larvae. The composition of each experimental mixture rapidly converged to a common equilibrium with a genotypic composition of ∼85% SfNIC-B plus ∼15% SfNIC-BΔ16K. Nearly identical results were observed in peroral-passage experiments involving mixtures of SfNIC-B plus SfNIC-BΔpifs. We conclude that (i) the deletion of thepif1andpif2region is necessary and sufficient to explain the increased potency observed in mixtures of complete and deletion genotypes and (ii) viral populations with decreased ratios ofpif1- andpif2-deficient genotypes in the virus population increase the potency of genotypic mixtures and are likely to positively influence the transmission of this pathogen.
Characterization of Respiratory Syncytial Virus M- and M2-Specific CD4 T Cells in a Murine Model
Authors: Liu Jie , Ruckwardt Tracy J. , Chen Man , Johnson Teresa R. , Graham Barney S.
Published: March 2009

CD4 T cells have been shown to play an important role in the immunity and immunopathogenesis of respiratory syncytial virus (RSV) infection. We identified two novel CD4 T-cell epitopes in the RSV M and M2 proteins with core sequences M213-223(FKYIKPQSQFI) and M227-37(YFEWPPHALLV). Peptides containing the epitopes stimulated RSV-specific CD4 T cells to produce gamma interferon (IFN-γ), interleukin 2 (IL-2), and other Th1- and Th2-type cytokines in an I-Ab-restricted pattern. Construction of fluorochrome-conjugated peptide-I-Abclass II tetramers revealed RSV M- and M2-specific CD4 T-cell responses in RSV-infected mice in a hierarchical pattern. Peptide-activated CD4 T cells from lungs were more activated and differentiated, and had greater IFN-γ expression, than CD4 T cells from the spleen, which, in contrast, produced greater levels of IL-2. In addition, M209-223peptide-activated CD4 T cells reduced IFN-γ and IL-2 production in M- and M2-specific CD8 T-cell responses to Db-M187-195and Kd-M282-90peptides more than M225-39peptide-stimulated CD4 T cells. This correlated with the fact that I-Ab-M209-223tetramer-positive cells responding to primary RSV infection had a much higher frequency of FoxP3 expression than I-Ab-M226-39tetramer-positive CD4 T cells, suggesting that the M-specific CD4 T-cell response has greater regulatory function. Characterization of epitope-specific CD4 T cells by novel fluorochrome-conjugated peptide-I-Abtetramers allows detailed analysis of their roles in RSV pathogenesis and immunity.
Involvement of Creatine Kinase B in Hepatitis C Virus Genome Replication through Interaction with the Viral NS4A Protein
Authors: Hara Hiromichi , Aizaki Hideki , Matsuda Mami , Shinkai-Ouchi Fumiko , Inoue Yasushi , Murakami Kyoko , Shoji Ikuo , Kawakami Hayato , Matsuura Yoshiharu , Lai Michael M. C. , Miyamura Tatsuo , Wakita Takaji , Suzuki Tetsuro
Published: March 2009

Persistent infection with hepatitis C virus (HCV) is a major cause of chronic liver diseases. The aim of this study was to identify host cell factor(s) participating in the HCV replication complex (RC) and to clarify the regulatory mechanisms of viral genome replication dependent on the host-derived factor(s) identified. By comparative proteome analysis of RC-rich membrane fractions and subsequent gene silencing mediated by RNA interference, we identified several candidates for RC components involved in HCV replication. We found that one of these candidates, creatine kinase B (CKB), a key ATP-generating enzyme that regulates ATP in subcellular compartments of nonmuscle cells, is important for efficient replication of the HCV genome and propagation of infectious virus. CKB interacts with HCV NS4A protein and forms a complex with NS3-4A, which possesses multiple enzyme activities. CKB upregulates both NS3-4A-mediated unwinding of RNA and DNA in vitro and replicase activity in permeabilized HCV replicating cells. Our results support a model in which recruitment of CKB to the HCV RC compartment, which has high and fluctuating energy demands, through its interaction with NS4A is important for efficient replication of the viral genome. The CKB-NS4A association is a potential target for the development of a new type of antiviral therapeutic strategy.
Suppression of Host Gene Expression by nsp1 Proteins of Group 2 Bat Coronaviruses
Authors: Tohya Yukinobu , Narayanan Krishna , Kamitani Wataru , Huang Cheng , Lokugamage Kumari , Makino Shinji
Published: March 2009

nsp1 protein of severe acute respiratory syndrome coronavirus (SARS-CoV), a group 2b CoV, suppresses host gene expression by promoting host mRNA degradation and translation inhibition. The present study analyzed the activities of nsp1 proteins from the group 2 bat CoV strains Rm1, 133, and HKU9-1, belonging to groups 2b, 2c, and 2d, respectively. The host mRNA degradation and translational suppression activities of nsp1 of SARS-CoV and Rm1 nsp1 were similar and stronger than the activities of the nsp1 proteins of 133 and HKU9-1. Rm1 nsp1 expression intransstrongly inhibited the induction of type I interferon (IFN-I) and IFN-stimulated genes in cells infected with an IFN-inducing SARS-CoV mutant, while 133 and HKU9-1 nsp1 proteins had relatively moderate IFN-inhibitory activities. The results of our studies suggested a conserved function among nsp1 proteins of SARS-CoV and group 2 bat CoVs.
Arginine Methylation of Human Adenovirus Type 5 L4 100-Kilodalton Protein Is Required for Efficient Virus Production
Authors: Koyuncu Orkide Ö. , Dobner Thomas
Published: March 2009

The adenovirus type 5 (Ad5) late region 4 (L4) 100-kDa nonstructural protein (L4-100K) mediates inhibition of cellular protein synthesis and selective translation of tripartite leader (TL)-containing viral late mRNAs via ribosome shunting. In addition, L4-100K has been implicated in the trimerization and nuclear localization of hexon protein. We previously proved that L4-100K is a substrate of the protein arginine methylation machinery, an emergent posttranslational modification system involved in a growing list of cellular processes, including transcriptional regulation, cell signaling, RNA processing, and DNA repair. As understood at present, L4-100K arginine methylation involves protein arginine methyltransferase 1 (PRMT1), which asymmetrically dimethylates arginines embedded in arginine-glycine-glycine (RGG) or glycine-arginine-rich (GAR) domains. To identify the methylated arginine residues and assess the role of L4-100K arginine methylation, we generated amino acid substitution mutations in the RGG and GAR motifs to examine their effects in Ad-infected and plasmid-transfected cells. Arginine-to-glycine exchanges in the RGG boxes significantly diminished L4-100K methylation in the course of an infection and substantially reduced virus growth, demonstrating that L4-100K methylation in RGG motifs is an important host cell function required for efficient Ad replication. Our data further indicate that PRMT1-catalyzed arginine methylation in the RGG boxes regulates the binding of L4-100K to hexon and promotes the capsid assembly of the structural protein as well as modulating TL-mRNA interaction. Furthermore, substitutions in GAR, but not RGG, regions affected L4-100K nuclear import, implying that the nuclear localization signal of L4-100K is located within the GAR sequence.
Analysis of the Functions of Herpes Simplex Virus Type 1 Regulatory Protein ICP0 That Are Critical for Lytic Infection and Derepression of Quiescent Viral Genomes
Authors: Everett Roger D. , Parsy Marie-Laure , Orr Anne
Published: March 2009

Herpes simplex virus type 1 (HSV-1) immediate-early regulatory protein ICP0 is important for stimulating the initiation of the lytic cycle and efficient reactivation of latent or quiescent infection. Extensive investigation has suggested several potential functions for ICP0, including interference in the interferon response, disruption of functions connected with PML nuclear bodies (ND10), and inhibition of cellular histone deacetylase (HDAC) activity through an interaction with the HDAC-1 binding partner CoREST. Analysis of the significance of these potential functions and whether they are direct or indirect effects of ICP0 is complicated because HSV-1 mutants expressing mutant forms of ICP0 infect cells with widely differing efficiencies. On the other hand, transfection approaches for ICP0 expression do not allow studies of whole cell populations because of their limited efficiency. To overcome these problems, we have established a cell line in which ICP0 expression can be induced at levels pertaining during the early stages of HSV-1 infection in virtually all cells in the culture. Such cells enable 100% complementation of ICP0-null mutant HSV-1. Using cells expressing the wild type and a variety of mutant forms of ICP0, we have used this system to analyze the role of defined domains of the protein in stimulating lytic infection and derepression from quiescence. Activity in these core functions correlated well the ability of ICP0 to disrupt ND10 and inhibit the recruitment of ND10 proteins to sites closely associated with viral genomes at the onset of infection, whereas the CoREST binding region was neither sufficient nor necessary for ICP0 function in lytic and reactivating infections.
STATE-BASED COMPOSITION IN UML 2
Authors: BARBIER FRANCK , ARETXANDIETA XABIER
Published: March 2009

The Composition relationship or "black diamond" in the Unified Modeling Language (UML) is recognized for a long time as a key modeling construct. While prior research works demonstrated that this modeling operator had a dubious semantics, new expectations in the field of Component-Based Software Engineering especially, lead to revisit this operator so that it supports dynamical composition, and more precisely, composition modeling expressions and implementations that safely refer to states of software components. At first, the revision of the UML Composition must rely on well-formalized static dependencies between components as, for instance, the property of lifetime dependency between compound and constituent entities. This papers offers a UML metamodel and some associated logical assertions to strengthen the Composition relationship in UML 2. Despite the presence of new diagram types dedicated to composition (i.e., Composite Structure Diagrams), the UML 2 composition model is not yet sufficiently exhaustive and formal for dealing with all cases of composition, including those relating to agent, component or service computing and modeling.
MINIMUM SEPARATION IN WEIGHTED SUBDIVISIONS
Authors: DAESCU OVIDIU , PALMER JAMES
Published: March 2009

We present polynomial time results for computing a minimum separation between two regions in a planar weighted subdivision. Our results are based on a (more general) theorem that characterizes a class of functions for which optimal solutions arise on the boundary of the feasible domain. A direct consequence of this theorem is that a minimum separation goes through a vertex of the weighted subdivision. We also consider extensions and present results for the 3-D case and for a more general case of the 2-D separation problem, in which the separation (link) has associated an ϵ-width. Our results are the first nontrivial upper bounds for these problems. We also discuss simple approximation algorithms for the 2-D case and present a prune-and-search approach that can be used with either the continuous or the approximate solutions to speed up the computation. We have implemented a variant of the two region minimum separation algorithm based on the prune-and-search scheme.
CLEARING A POLYGON WITH TWO 1-SEARCHERS
Authors: SIMOV BORISLAV H. , SLUTZKI GIORA , LAVALLE STEVEN M.
Published: March 2009

We present an algorithm for a pair of pursuers, each with one flashlight, searching for an unpredictable, moving target in a 2D environment (simple polygon). Given a polygon with n edges and m concave regions, the algorithm decides in time O(n2+ nm2+ m4) whether the polygon can be cleared by the two 1-searchers, and if so, constructs a search schedule. The pursuers are allowed to move on the boundary and in the interior of the polygon. They are not required to maintain mutual visibility throughout the pursuit.
Addition of carbenes derived from aryldiazoacetates to arenes using chloro(tetraphenylporphyrinato)iron as catalyst
Authors: Mbuvi Harun M. , Keith Woo L.
Published: March 2009

Chloro(tetraphenylporphyrinato)iron, Fe ( TPP ) Cl , is an active catalyst for the Büchner addition of para-substituted methyl 2-phenyldiazoacetates, 1a–d, to substituted benzenes. Yields greater than 70% have been achieved at temperatures ranging from 60–100°C. Reactions of substituted methyl 2-phenyldiazoacetates with benzene gave rapidly equilibrating mixtures of norcaradienecycloheptatriene valence isomers, 2a–d/2′a–d, in yields over 70%. Treatment of chlorobenzene with methyl 2-phenyldiazoacetate produced a regio-isomeric mixture of 7-carbomethoxy-2-chloro-7-phenylnorcaradiene/7-carbomethoxy-2-chloro-7-phenylcycloheptatriene, 3a/3′a, and 7-carbomethoxy-3-chloro-7-phenylnorcaradiene/7-carbomethoxy-3-chloro-7-phenylcycloheptatriene, 4a/4′a. When p-methylanisole was treated with methyl 2-phenyldiazoacetate at 80°C, a product that largely favored a fused cyclopropane structure, 7-carbomethoxy-2-methoxy-5-methyl-7-phenylnorcaradiene, 12a, was obtained along with the benzylic C–H insertion product methyl 3-(p-methoxyphenyl)-2-phenylpropionate, 13a. Heating the norcaradiene product 12a at 110°C yielded the ring-opened diarylacetate, 14a. The diene forms of the fluxional norcaradiene-cycloheptatriene systems were trapped with benzyne to give one stereoisomer of 3,3-disubstituted benzhomobarralenes, 18a–d. The norcaradiene-cycloheptatriene valence isomers were quantitatively converted into ring-opened diaryl acetate products upon acidification in acetonitrile. Rates for the addition of methyl (p-chlorophenyl)diazoacetate to benzene were first order with respect to the diazo reagent. A concerted mechanism involing an iron carbene complex is proposed for these iron porphyrin-catalyzed Büchner reactions.