bluuebunny/crossref_metadata_2025 huggingface dataset:
Co-Combustion of Coal With Rice Husk and Bamboo in Power Generation
Authors: Chao Christopher Y. H. , Kwong Philip C. W. , Wang J. H.
Published: February 2009

In many Asian countries Coal is frequently used a major fuel in power plants. Burning coal creates quite a lot of environmental problems when compared to other cleaner fuels such as natural gas. Experimental study of co-combustion of coal and biomass was conducted in a laboratory scale combustion facility to evaluate the combustion and pollutant emission performance under different operation parameters. Rice husk and bamboo were used as the biomass fuels in this study. This paper reported the influence of the biomass blending ratio in the fuel mixture and the excess air ratio on the combustion behavior. It was noted that the combustion temperature and the energy output from the co-firing process were reduced compared to coal combustion alone owing to the fact that biomass has lower heating value compared to coal. However, the high volatile matter (VM) content of biomass improved the combustion time scale so that the carbon monoxide (CO) emissions were reduced substantially. In addition, the fuel nitrogen and sulfur content in biomass were lower than that of coal and hence suppressed the formation of nitrogen oxides (NOx) and sulfur dioxide (SO2) during the cocombustion process. The increase of excess air ratio also affected most of the pollutant emissions. The pollutant emission per unit energy output at different excess air ratios and biomass blending ratios were studied in detail in this paper. Attention should be paid to the high potential of slagging and fouling in the boiler when co-firing coal with biomass.
Adopting Nitrate/Nitrite Salt Mixtures as the Heat Transport Fluid in Parabolic Trough Power Plants
Authors: Kelly Bruce , Price Henry , Brosseau Doug , Kearney David
Published: February 2009

The present generation of commercial parabolic trough solar power plant uses a synthetic oil as the heat transport fluid in the collector field. The plants are currently operating at the upper temperature limit of the fluid, and further improvements in the solar-to-electric conversion efficiency are likely to be incremental. In contrast, adoption of a nitrate salt, or a nitrate/nitrite salt, mixture as the heat transport fluid would allow the collector field outlet temperature to increase by 50 to 100 °C, which translates into an increase in the gross Rankine cycle efficiency from the present 37.5 percent to new values in the range of 40 to 41 percent. Further, the low cost and the low vapor pressure of the candidate salt mixtures allow the heat transport fluid to also act as the storage medium in a thermal storage system. Using a salt mixture in the collector field should reduce the unit cost of thermal storage by approximately half compared to the current indirect designs. The principal, and far from minor, liability of the candidate salt mixtures are freezing points in the range of 120 °C to 220 °C. As a consequence, all salt components, including the collector field, will require some form of electric heating for freeze protection. Further, collector designs will need to be demonstrated, or developed, which are tolerant of a limited number of freeze/thaw cycles. The candidate salts are also corrosive to the current ball joint sealing materials. This paper outlines the problems which need to be solved before a commercial salt project could reasonably be considered by a project developer, the elements of a test and demonstration program to solve the problems, and the contributions which will be necessary from the salt component vendors, the project developers, and the financial community.
Assessment of Wind Energy for Nevada Using Towers and Mesoscale Modeling
Authors: Koracin Darko , Reinhardt Richard L. , Liddle Marshall B. , McCord Travis , Podnar Domagoj , Minor Timothy B.
Published: February 2009

The main objectives of the study were to support wind energy assessment for all of Nevada by providing two annual cycles of high-resolution mesoscale modeling evaluated by data from surface stations and towers, estimating differences between these annual cycles and standard wind maps, and providing wind and wind power density statistics at elevations relevant to turbine operations. In addition to the 65 existing Remote Automated Weather Stations in Nevada, four 50-m-tall meteorological towers were deployed in western Nevada to capture long-term wind characteristics and provide database input to verify and improve modeling results. The modeling methodology using Mesoscale Model 5 (MM5) was developed to provide wind and wind power density estimates representing mesoscale effects that include actual synoptic forcing during the two annual cycles (horizontal resolution on the order of 2 and 3 km). The results from the two annual simulation cycles show similar wind statistics with an average difference of less than 100 W/m2. The available TrueWind results for the wind power density at 50 m show greater values of wind power density compared to both MM5-simulated annual cycles for most of the area. However, mainly in the Sierras and the mountainous regions of southern and eastern Nevada, the MM5 simulations indicate greater values for wind power density. The results of this study suggest that the synthesis of the data from a network of tower observations and high-resolution mesoscale modeling is a crucial tool for assessing the wind power density in Nevada and, more generally, other topographically developed areas.
Heliostat Cost Reduction
Authors: Kolb Gregory J. , Davenport Roger , Gorman David , Lumia Ron , Thomas Robert , Donnelly Matthew
Published: February 2009

Power towers are capable of producing solar-generated electricity and hydrogen on a large scale. Heliostats are the most important cost element of a solar power tower plant. Since they constitute ∼50% to the capital cost of the plant it is important to reduce the cost of heliostats to as low as possible to improve the economic viability of power towers. In this study we evaluate current heliostat technology and estimate a price of $126/m2 given year 2006 materials and labor costs. We also propose R&D that should ultimately lead to a price of less than $100/m2. Approximately 30 heliostat and manufacturing experts from the USA, Europe, and Australia contributed to the content of this report during 2 workshops conducted at the National Solar Thermal Test Facility.
Optimization of BCHP Schemes Based on GRA and AHP
Authors: Bing Wei , Wang Zhiwei , Li Li , Lu Jiang
Published: February 2009

BCHP (Building Cooling, Heating and Power) system is an integrated energy system based on the energy cascade utilization and is used to supply heating, cooling and power synchronously. Normally the scale of BCHP system is smaller than that of the CCHP (Combined Cooling Heating and Power) system of thermal power plant. BCHP system is one of the most important directions of the second generation energy system and distributed energy system and has advantages of energy conservation, environment protection and safety performance, etc. In this paper with the example of an actual building, by using the theories of GRA (Grey Relation Analysis) and AHP (Analytical Hierarchy Process) the mathematical models for the comprehensive evaluation of BCHP system are established. Three schemes of BCHP systems are given and the indexes of economy, environment protection, energy conservation and reliability are considered as the main factors in the project selection of BCHP system. The optimal scheme is selected according to the cooling, heating and power loads of the building. In the optimization process, both the evaluation indexes and the weight coefficients are chosen objectively to improve the comprehensive and scientific performance of BCHP project selection.
A Simplified Method to Predict Energy Cost Savings in Office Buildings Using a Hybrid Desiccant, Absorption Chiller, and Natural Gas Turbine Cogeneration System With Thermal Storage
Authors: McNeill James , Previtali Jon , Krarti Moncef
Published: February 2009

This paper provides a simplified analysis tool to predict the energy savings associated with the usage of a hybrid air conditioning system that combines liquid desiccant, absorption chiller, natural gas turbine cogeneration system with thermal storage (hereafter hybrid cogeneration system) versus a watercooled centrifugal chiller with a natural gas boiler (hereafter conventional system). The hybrid cogeneration system is controlled to track both electrical and thermal loads. The simplified analysis method is formulated from detailed energy simulation models. A direct correlation has been determined between the energy cost savings of using the hybrid cogeneration system instead of the conventional system and the cogeneration capacity, peak electricity rate, and natural gas rate for five U.S. cities: Atlanta, Chicago, Denver, New York, and San Francisco.
Lighting Energy Savings From Daylighting Through Skylights for Warehouses
Authors: Mechergui Aymen , Krarti Moncef
Published: February 2009

The paper provides the results of a simulation-based analysis to estimate the potential savings in electrical lighting energy use associated with daylighting controls using skylights for open space warehouses. First, the effectiveness of daylighting controls is investigated for several skylight opening areas, glazing types, control strategies, and several locations in Tunisia. A simplified calculation method is then developed to estimate the annual savings in electrical lighting energy use due to daylighting controls in warehouses. The simplified method has been developed and validated for several locations throughout the world.
Energy Consumption Simulation for Residential Buildings With Shading Devices in Different Regions
Authors: Liu Junjie , Zhou Xiaojie , Gao Zhihong
Published: February 2009

With the development of energy saving, it is needed to calculate the energy consumption of the residential building, particularly accurate dynamic energy consumption. Fixed shading devices are wildly used to save building energy because they prevent undesirable heat coming through the windows during the “overheated period”, just as in summer, which can ameliorate the indoor environments and reduce the energy consumption of air-conditioning in summer. But they will also prevent solar energy which can be used in winter to enter windows. So it is very important to be able to determine the optimal shading devices of windows. The overhangs and vertical-shading devices are representative to study the different energy performance in summer and winter, in an actual dwell house. On the other hand, fixed shading devices can weaken the effect of daylighting, so we would take both the total energy consumption and rooms’ daylighting into account. In this study, we choose several typical dwelling houses in different cities located in north, south, west, east and central region of China respectively. We calculated energy consumption of those models by using Energyplus program, and compared the shading performance of horizontal and vertical shading devices, then optimal configuration dimensions of horizontal shading devices are recommended on the basis of different requirements for solar heat gains in winter and in summer for those typical dwelling houses.
Energy and Exergy Analyses of a Natural Gas Fired Combined Cycle Cogeneration System
Authors: Law B. , Reddy B. V.
Published: February 2009

Combined cycle cogeneration systems have the ability to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. In the present work the performance of a natural gas fired combined cycle cogeneration unit with multiple process heaters is investigated to study the effect of operating variables on the performance. The operating conditions investigated include, gas turbine pressure ratio, process heat loads and process steam extraction pressure. The gas turbine pressure ratio significantly influences the performance of the combined cycle cogeneration system. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. The exergy analysis is conducted to identify the exergy destruction and losses in different components of the combined cycle cogeneration unit.
Predicting Elections: Child's Play!
Authors: Antonakis John , Dalgas Olaf
Published: February 2009

In two experiments, children and adults rated pairs of faces from election races. Na�ve adults judged a pair on competence; after playing a game, children chose who they would prefer to be captain of their boat. Children's (as well as adults') preferences accurately predicted actual election outcomes.
Comment on "Multipartite Entanglement Among Single Spins in Diamond"
Authors: Lovett Brendon W. , Benjamin Simon C.
Published: February 2009

Neumann
et al
. (Reports, 6 June 2008, p. 1326) recently reported the preparation of multiparticle entanglement among single spins in diamond. However, two of the system's nuclear eigenstates are incorrectly described as product states when they are inherently entangled. Consequently, three of the six states reported, namely the odd-parity Bell states and the
W
state, were not actually produced.
Response to Comment on "Multipartite Entanglement Among Single Spins in Diamond"
Authors: Neumann P. , Mizuochi N. , Rempp F. , Hemmer P. , Watanabe H. , Yamasaki S. , Jacques V. , Gaebel T. , Jelezko F. , Wrachtrup J.
Published: February 2009

Our study reported entanglement among single spins in diamond. Lovett and Benjamin argue that three of six described entangled states were not achieved. Here, we explain our choice of entangled states and discuss their importance for quantum information processing. We also show that the eigenstates discussed by Lovett and Benjamin, although formally entangled and routinely generated in our experiments, cannot be used to detect nonlocal correlations.
Recombinant Vesicular Stomatitis Virus Expressing Influenza Nucleoprotein Induces CD8 T-Cell Responses That Enhance Antibody-Mediated Protection after Lethal Challenge with Influenza Virus
Authors: Barefoot Brice E. , Sample Christopher J. , Ramsburg Elizabeth A.
Published: February 2009

Live attenuated vaccine vectors based on recombinant vesicular stomatitis viruses (rVSVs) expressing foreign antigens are highly effective vaccines in animal models. In this study, we report that an rVSV expressing influenza nucleoprotein (VSV NP) from the first position of the VSV genome induces robust anti-NP CD8 T cells in immunized mice. These CD8 T cells are phenotypically similar to those induced by natural influenza infection and are cytotoxic in vivo. Animals immunized with an rVSV expressing the influenza hemagglutinin (rVSV HA) were protected but still exhibited considerable morbidity after challenge. Animals receiving a cocktail vaccine of rVSV NP and rVSV HA had reduced pulmonary viral loads, less weight loss, and reduced clinical signs of illness after influenza virus challenge, relative to those vaccinated with rVSV HA alone. Influenza NP is a highly conserved antigen, and induction of protective anti-NP responses may be a productive strategy for generating heterologous protection against divergent influenza strains.
Species-Specific Identification of a Wide Range of Clinically Relevant Fungal Pathogens by Use of Luminex xMAP Technology
Authors: Landlinger C. , Preuner S. , Willinger B. , Haberpursch B. , Racil Z. , Mayer J. , Lion T.
Published: February 2009

In immunocompromised patients suffering from invasive fungal infection, rapid identification of the fungal species is a prerequisite for selection of the most appropriate antifungal treatment. We present an assay permitting reliable identification of a wide range of clinically relevant fungal pathogens based on the high-throughput Luminex microbead hybridization technology. The internal transcribed spacer (ITS2) region, which is highly variable among genomes of individual fungal species, was used to generate oligonucleotide hybridization probes for specific identification. The spectrum of pathogenic fungi covered by the assay includes the most commonly occurring species of the genera
Aspergillus
and
Candida
and a number of important emerging fungi, such as
Cryptococcus, Fusarium, Trichosporon, Mucor, Rhizopus, Penicillium, Absidia, and Acremonium
. Up to three different probes are employed for the detection of each fungal species. The redundancy in the design of the assay should ensure unambiguous fungus identification even in the presence of mutations in individual target regions. The current set of hybridization oligonucleotides includes 75 species- and genus-specific probes which had been carefully tested for specificity by repeated analysis of multiple reference strains. To provide adequate sensitivity for clinical application, the assay includes amplification of the ITS2 region by a seminested PCR approach prior to hybridization of the amplicons to the probe panel using the Luminex technology. A variety of fungal pathogens were successfully identified in clinical specimens that included peripheral blood, samples from biopsies of pulmonary infiltrations, and bronchotracheal secretions derived from patients with documented invasive fungal infections. Our observations demonstrate that the Luminex-based technology presented permits rapid and reliable identification of fungal species and may therefore be instrumental in routine clinical diagnostics.
Mitochondrion-Enriched Anionic Phospholipids Facilitate Flock House Virus RNA Polymerase Membrane Association
Authors: Stapleford Kenneth A. , Rapaport Doron , Miller David J.
Published: February 2009

One characteristic of all positive-strand RNA viruses is the necessity to assemble viral RNA replication complexes on host intracellular membranes, a process whose molecular details are poorly understood. To study viral replication complex assembly we use the established model system of Flock House virus (FHV), which assembles its replication complexes on the mitochondrial outer membrane. The FHV RNA-dependent RNA polymerase, protein A, is the only viral protein necessary for genome replication in the budding yeast
Saccharomyces cerevisiae
. To examine the host components involved in protein A-membrane interactions, an initial step of FHV RNA replication complex assembly, we established an in vitro protein A membrane association assay. Protein A translated in vitro rapidly and specifically associated with mitochondria isolated from yeast, insect, and mammalian cells. This process was temperature dependent but independent of protease-sensitive mitochondrial outer membrane components or the host mitochondrial import machinery. Furthermore, lipid-binding studies revealed that protein A preferentially bound to specific anionic phospholipids, in particular the mitochondrion-specific phospholipid cardiolipin. These studies implicate membrane phospholipids as important host determinants for FHV RNA polymerase membrane association and provide evidence for the involvement of host phospholipids in positive-strand RNA virus membrane-specific targeting.
Temporal Regulation of the Mre11-Rad50-Nbs1 Complex during Adenovirus Infection
Authors: Karen Kasey A. , Hoey Peter J. , Young C. S. H. , Hearing Patrick
Published: February 2009

Adenovirus infection induces a cellular DNA damage response that can inhibit viral DNA replication and ligate viral genomes into concatemers. It is not clear if the input virus is sufficient to trigger this response or if viral DNA replication is required. Adenovirus has evolved two mechanisms that target the Mre11-Rad50-Nbs1 (MRN) complex to inhibit the DNA damage response. These include E4-ORF3-dependent relocalization of MRN proteins and E4-ORF6/E1B-55K-dependent degradation of MRN components. The literature suggests that degradation of the MRN complex due to E4-ORF6/E1B-55K does not occur until after viral DNA replication has begun. We show that, by the time viral DNA accumulates, the MRN complex is inactivated by either of the E4-induced mechanisms and that, with E4-ORF6/E1B-55K, this inactivation is due to MRN degradation. Our data are consistent with the conclusion that input viral DNA is sufficient to induce the DNA damage response. Further, we demonstrate that when the DNA damage response is active in E4 mutant virus infections, the covalently attached terminal protein is not cleaved from viral DNAs, and the viral origins of replication are not detectably degraded at a time corresponding to the onset of viral replication. The sequences of concatemeric junctions of viral DNAs were determined, which supports the conclusion that nonhomologous end joining mediates viral DNA ligation. Large deletions were found at these junctions, demonstrating nucleolytic procession of the viral DNA; however, the lack of terminal protein cleavage and terminus degradation at earlier times shows that viral genome deletion and concatenation are late effects.
Primary B-Cell Infection with a ΔBALF4 Epstein-Barr Virus Comes to a Halt in the Endosomal Compartment yet Still Elicits a Potent CD4-Positive Cytotoxic T-Cell Response
Authors: Neuhierl Bernhard , Feederle Regina , Adhikary Dinesh , Hub Birgit , Geletneky Karsten , Mautner Josef , Delecluse Henri-Jacques
Published: February 2009

Epstein-Barr virus (EBV) infection is mediated by several viral envelope glycoproteins. We have assessed gp110's functions during the virus life cycle using a mutant that lacks BALF4 (ΔBALF4). Exposure of various cell lines and primary cell samples of epithelial or lymphoid lineages to the ΔBALF4 mutant failed to establish stable infections. The ΔBALF4 virus, however, did not differ from wild-type EBV in its ability to bind and become internalized into primary B cells, in which it elicited a potent T-cell-specific immune reaction against virion constituents. These findings show that ΔBALF4 viruses can reach the endosome-lysosome compartment and dovetail nicely with the previously identified contribution of gp110 to virus-cell fusion. Other essential steps of the virus life cycle were unaffected in the viral mutant; DNA lytic replication and viral titers were not altered in the absence of gp110, and ΔBALF4 viruses complemented in
trans
transformed infected B cells with an efficiency indistinguishable from that observed with wild-type viruses. All of the steps of virus maturation could be observed in lytically induced 293/ΔBALF4 cells. Induction of lymphoblastoid cells generated with transiently complemented ΔBALF4 virus led to the production of rare mature virions. We therefore infer that gp110 is not required for virus maturation and egress in 293 cells or in B cells. The ΔBALF4 virus's phenotypic traits, an inability to infect human cells coupled with potent antigenicity, potentially qualify this mutant as a live vaccine. It will provide a useful tool for the detailed study of EBV-cell interactions in a physiological context.
NF-κB Serves as a Cellular Sensor of Kaposi's Sarcoma-Associated Herpesvirus Latency and Negatively Regulates K-Rta by Antagonizing the RBP-Jκ Coactivator
Authors: Izumiya Yoshihiro , Izumiya Chie , Hsia Datsun , Ellison Thomas J. , Luciw Paul A. , Kung Hsing-Jien
Published: February 2009

Successful viral replication is dependent on a conducive cellular environment; thus, viruses must be sensitive to the state of their host cells. We examined the idea that an interplay between viral and cellular regulatory factors determines the switch from Kaposi's sarcoma-associated herpesvirus (KSHV) latency to lytic replication. The immediate-early gene product K-Rta is the first viral protein expressed and an essential factor in reactivation; accordingly, this viral protein is in a key position to serve as a viral sensor of cellular physiology. Our approach aimed to define a host transcription factor, i.e., host sensor, which modulates K-Rta activity on viral promoters. To this end, we developed a panel of reporter plasmids containing all 83 putative viral promoters for a comprehensive survey of the response to both K-Rta and cellular transcription factors. Interestingly, members of the NF-κB family were shown to be strong negative regulators of K-Rta transactivation for all but two viral promoters (Ori-RNA and K12). Recruitment of K-Rta to the ORF57 and K-bZIP promoters, but not the K12 promoter, was significantly impaired when NF-κB expression was induced. Many K-Rta-responsive promoters modulated by NF-κB contain the sequence of the RBP-Jκ binding site, a major coactivator which anchors K-Rta to target promoters via consensus motifs which overlap with that of NF-κB. Gel shift assays demonstrated that NF-κB inhibits the binding of RBP-Jκ and forms a complex with RBP-Jκ. Our results support a model in which a balance between K-Rta/RBP-Jκ and NF-κB activities determines KSHV reactivation. An important feature of this model is that the interplay between RBP-Jκ and NF-κB on viral promoters controls viral gene expression mediated by K-Rta.
HLA Footprints on Human Immunodeficiency Virus Type 1 Are Associated with Interclade Polymorphisms and Intraclade Phylogenetic Clustering
Authors: Matthews Philippa C. , Leslie Alasdair J. , Katzourakis Aris , Crawford Hayley , Payne Rebecca , Prendergast Andrew , Power Karen , Kelleher Anthony D. , Klenerman Paul , Carlson Jonathan , Heckerman David , Ndung'u Thumbi , Walker Bruce D. , Allen Todd M. , Pybus Oliver G. , Goulder Philip J. R.
Published: February 2009

The selection of escape mutations has a major impact on immune control of infections with viruses such as human immunodeficiency virus (HIV). Viral evasion of CD8
+
T-cell responses leaves predictable combinations of escape mutations, termed HLA “footprints.” The most clearly defined footprints are those associated with HLA alleles that are linked with successful control of HIV, such as HLA-B*57. Here we investigated the extent to which HLA footprint sites in HIV type 1 (HIV-1) are associated with viral evolution among and within clades. First, we examined the extent to which amino acid differences between HIV-1 clades share identity with sites of HLA-mediated selection pressure and observed a strong association, in particular with respect to sites of HLA-B selection (
P
< 10
−6
). Similarly, the sites of amino acid variability within a clade were found to overlap with sites of HLA-selected mutation. Second, we studied the impact of HLA selection on interclade phylogeny. Removing the sites of amino acid variability did not significantly affect clade-specific clustering, reflecting the central role of founder effects in establishing distinct clades. However, HLA footprints may underpin founder strains, and we show that amino acid substitutions between clades alter phylogeny, underlining a potentially substantial role for HLA in driving ongoing viral evolution. Finally, we investigated the impact of HLA selection on within-clade phylogeny and demonstrate that even a single HLA allele footprint can result in significant phylogenetic clustering of sequences. In conclusion, these data highlight the fact that HLA can be a strong selection force for both intra- and interclade HIV evolution at a population level.
The Epstein-Barr Virus (EBV) Deubiquitinating Enzyme BPLF1 Reduces EBV Ribonucleotide Reductase Activity
Authors: Whitehurst Christopher B. , Ning Shunbin , Bentz Gretchen L. , Dufour Florent , Gershburg Edward , Shackelford Julia , Langelier Yves , Pagano Joseph S.
Published: February 2009

A newly discovered virally encoded deubiquitinating enzyme (DUB) is strictly conserved across the
Herpesviridae
. Epstein-Barr virus (EBV) BPLF1 encodes a tegument protein (3,149 amino acids) that exhibits deubiquitinating (DUB) activity that is lost upon mutation of the active-site cysteine. However, targets for the herpesviral DUBs have remained elusive. To investigate a predicted interaction between EBV BPLF1 and EBV ribonucleotide reductase (RR), a functional clone of the first 246 N-terminal amino acids of BPLF1 (BPLF1 1-246) was constructed. Immunoprecipitation verified an interaction between the small subunit of the viral RR2 and BPLF1 proteins. In addition, the large subunit (RR1) of the RR appeared to be ubiquitinated both in vivo and in vitro; however, ubiquitinated forms of the small subunit, RR2, were not detected. Ubiquitination of RR1 requires the expression of both subunits of the RR complex. Furthermore, coexpression of RR1 and RR2 with BPLF1 1-246 abolishes ubiquitination of RR1. EBV RR1, RR2, and BPLF1 1-246 colocalized to the cytoplasm in HEK 293T cells. Finally, expression of enzymatically active BPLF1 1-246 decreased RR activity, whereas a nonfunctional active-site mutant (BPLF1 C61S) had no effect. These results indicate that the EBV deubiquitinating enzyme interacts with, deubiquitinates, and influences the activity of the EBV RR. This is the first verified protein target of the EBV deubiquitinating enzyme.
Ganglioside-Linked Terminal Sialic Acid Moieties on Murine Macrophages Function as Attachment Receptors for Murine Noroviruses
Authors: Taube Stefan , Perry Jeffrey W. , Yetming Kristen , Patel Sagar P. , Auble Heather , Shu Liming , Nawar Hesham F. , Lee Chang Hoon , Connell Terry D. , Shayman James A. , Wobus Christiane E.
Published: February 2009

Noroviruses are the major cause of nonbacterial gastroenteritis in humans. However, little is known regarding the norovirus life cycle, including cell binding and entry. In contrast to human noroviruses, the recently discovered murine norovirus 1 (MNV-1) readily infects murine macrophages and dendritic cells in culture. Many viruses, including the related feline calicivirus, use terminal sialic acids (SA) as receptors for infection. Therefore, we tested whether SA moieties play a role during MNV-1 infection of murine macrophages. Competition with SA-binding lectins and neuraminidase treatment led to a reduction in MNV-1 binding and infection in cultured and primary murine macrophages, suggesting a role for SA during the initial steps of the MNV-1 life cycle. Because SA moieties can be attached to glycolipids (i.e., gangliosides), we next determined whether MNV-1 uses gangliosides during infection. The gangliosides GD1a, GM1, and asialo-GM1 (GA1) are natural components of murine macrophages. MNV-1 bound to ganglioside GD1a, which is characterized by an SA on the terminal galactose, but not to GM1 or asialo-GM1 in an enzyme-linked immunosorbent assay. The depletion of gangliosides using an inhibitor of glycosylceramide synthase (
d
-
threo
-P4) led to a reduction of MNV-1 binding and infection in cultured and primary murine macrophages. This defect was specifically rescued by the addition of GD1a. A similar phenotype was observed for MNV field strains WU11 (GV/WU11/2005/USA) and S99 (GV/Berlin/2006/DE). In conclusion, our data indicate that MNV can use terminal SA on gangliosides as attachment receptors during binding to murine macrophages.
Epstein-Barr Virus Nuclear Antigen 3C Augments Mdm2-Mediated p53 Ubiquitination and Degradation by Deubiquitinating Mdm2
Authors: Saha Abhik , Murakami Masanao , Kumar Pankaj , Bajaj Bharat , Sims Karen , Robertson Erle S.
Published: February 2009

Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is one of the essential latent antigens for primary B-cell transformation. Previous studies established that EBNA3C facilitates degradation of several vital cell cycle regulators, including the retinoblastoma (pRb) and p27KIPproteins, by recruitment of the SCFSkp2E3 ubiquitin ligase complex. EBNA3C was also shown to be ubiquitinated at its N-terminal residues. Furthermore, EBNA3C can bind to and be degraded in vitro by purified 20S proteasomes. Surprisingly, in lymphoblastoid cell lines, EBNA3C is extremely stable, and the mechanism for this stability is unknown. In this report we show that EBNA3C can function as a deubiquitination enzyme capable of deubiquitinating itself in vitro as well as in vivo. Functional mapping using deletion and point mutational analysis showed that both the N- and C-terminal domains of EBNA3C contribute to the deubiquitination activity. We also show that EBNA3C efficiently deubiquitinates Mdm2, an important cellular proto-oncogene, which is known to be overexpressed in several human cancers. The data presented here further demonstrate that the N-terminal domain of EBNA3C can bind to the acidic domain of Mdm2. Additionally, the N-terminal domain of EBNA3C strongly stabilizes Mdm2. Importantly, EBNA3C simultaneously binds to both Mdm2 and p53 and can form a stable ternary complex; however, in the presence of p53 the binding affinity of Mdm2 toward EBNA3C was significantly reduced, suggesting that p53 and Mdm2 might share a common overlapping domain of EBNA3C. We also showed that EBNA3C enhances the intrinsic ubiquitin ligase activity of Mdm2 toward p53, which in turn facilitated p53 ubiquitination and degradation. Thus, manipulation of the oncoprotein Mdm2 by EBNA3C potentially provides a favorable environment for transformation and proliferation of EBV-infected cells.
Crystal Structure of Dengue Virus Type 1 Envelope Protein in the Postfusion Conformation and Its Implications for Membrane Fusion
Authors: Nayak Vinod , Dessau Moshe , Kucera Kaury , Anthony Karen , Ledizet Michel , Modis Yorgo
Published: February 2009

Dengue virus relies on a conformational change in its envelope protein, E, to fuse the viral lipid membrane with the endosomal membrane and thereby deliver the viral genome into the cytosol. We have determined the crystal structure of a soluble fragment E (sE) of dengue virus type 1 (DEN-1). The protein is in the postfusion conformation even though it was not exposed to a lipid membrane or detergent. At the domain I-domain III interface, 4 polar residues form a tight cluster that is absent in other flaviviral postfusion structures. Two of these residues, His-282 and His-317, are conserved in flaviviruses and are part of the “pH sensor” that triggers the fusogenic conformational change in E, at the reduced pH of the endosome. In the fusion loop, Phe-108 adopts a distinct conformation, forming additional trimer contacts and filling the bowl-shaped concavity observed at the tip of the DEN-2 sE trimer.
Optimal Transactivation by Epstein-Barr Nuclear Antigen 1 Requires the UR1 and ATH1 Domains
Authors: Singh Gyanendra , Aras Siddhesh , Zea Arnold H. , Koochekpour Shahriar , Aiyar Ashok
Published: February 2009

Epstein-Barr nuclear antigen 1 (EBNA1) is essential for Epstein-Barr virus to immortalize naïve B cells. EBNA1 transactivates viral promoters for genes that are necessary for immortalization when it is bound to a cluster of 20 cognate binding sites, termed the family of repeats. A region of EBNA1 from amino acids (aa) 40 to 89, termed linking region 1 (LR1), has been identified previously as being sufficient for transactivation. LR1 contains two domains that are conserved in the EBNA1 orthologs of other gamma herpesviruses. The first of these, termed unique region 1 (UR1), corresponds to aa 65 to 89 of EBNA1. UR1 is necessary for transactivation and contains a conserved recognition site for cyclic AMP-dependent protein kinase (PKA), corresponding to serine 78 of EBNA1. We have pharmacologically modulated PKA activity to determine if PKA controls EBNA1's ability to transactivate. Our results indicate that PKA activators and inhibitors do not affect transactivation by EBNA1. In addition, site-directed mutagenesis demonstrates that transactivation is not influenced by the phosphorylation status of serine 78 in the UR1 domain. The second conserved domain within LR1 is a glycine-arginine repeat, corresponding to aa 40 to 54 of EBNA1. This domain, termed ATH1, functions as an AT-hook, a DNA-binding motif found in architectural transcription factors such as HMGA1a. We demonstrate that deletion of the ATH1 domain decreases EBNA1 transactivation ability, which is consistent with a transcriptional role for ATH1. Furthermore, transactivation is restored when ATH1 is replaced by equivalent AT-hook motifs from HMGA1a. Our data strongly indicate a role for AT-hooks in EBNA1's ability to transactivate, a function necessary for EBV to immortalize naïve B-cells.
Hepatitis B Virus Replication and Release Are Independent of Core Lysine Ubiquitination
Authors: Garcia Mayra L. , Byfield Rushelle , Robek Michael D.
Published: February 2009

Ubiquitin conjugation to lysine residues regulates a variety of protein functions, including endosomal trafficking and degradation. While ubiquitin plays an important role in the release of many viruses, the requirement for direct ubiquitin conjugation to viral structural proteins is less well understood. Some viral structural proteins require ubiquitin ligase activity, but not ubiquitin conjugation, for efficient release. Recent evidence has shown that, like other viruses, hepatitis B virus (HBV) requires a ubiquitin ligase for release from the infected cell. The HBV core protein contains two lysine residues (K7 and K96), and K96 has been suggested to function as a potential ubiquitin acceptor site based on the fact that previous studies have shown that mutation of this amino acid to alanine blocks HBV release. We therefore reexamined the potential connection between core lysine ubiquitination and HBV replication, protein trafficking, and virion release. In contrast to alanine substitution, we found that mutation of K96 to arginine, which compared to alanine is more conserved but also cannot mediate ubiquitin conjugation, does not affect either virus replication or virion release. We also found that the core lysine mutants display wild-type sensitivity to the antiviral activity of interferon, which demonstrates that ubiquitination of core lysines does not mediate the interferon-induced disruption of HBV capsids. However, mutation of K96 to arginine alters the nuclear-cytoplasmic distribution of core, leading to an accumulation in the nucleolus. In summary, these studies demonstrate that although ubiquitin may regulate the HBV replication cycle, these mechanisms function independently of direct lysine ubiquitination of core protein.
A Thermal Analysis for Structures on permafrost
Authors: Hwang C. T. , Murray D. W. , Brooker E. W.
Published: February 2009

A short review of the complexities in the specification of physical properties for the solution of thermal problems in freezing and thawing soils is presented. The differential equations governing the conduction of heat, in which latent heat is considered as a heat source, are stated. An equivalent convolution variational theorem is used to construct a two-dimensional finite element model with linear variation of temperature within the element. Two time step idealizations of the equations are described and alternative forms of the latent heat matrix are derived. Some results obtained with the simplest latent heat matrix are presented, which include a problem of complex geometry, to illustrate the versatility of the technique.
Effects of Pile Driving in Clays
Authors: Flaate Kaare
Published: February 2009

This study summarizes the information given in the literature as well as observations made by the author. The effects of driving piles on remolding, stresses, and properties of the clay are considered. It is concluded that timber piles cause strong remolding of a zone extending to 10–15 cm from the pile surface. Strength and deformation properties will undergo changes beyond this zone as well. Pile type, pile density, soil properties, and driving conditions influence the results. There seems to be very small changes in the average water content, since the reduction adjacent to the pile is counter-balanced by an increase between the piles. The undrained shear strength adjacent to the pile is in one case found to be much higher than the skin friction at failure.
A Study of Anchorages for Transmission Tower Foundations
Authors: Adams J. I. , Klym T. W.
Published: February 2009

A number of uplift tests have been conducted on anchors proposed for use to support high voltage transmission line towers both for the conventional four legged structure and for the guyed-type structure with a single central footing. Tests were carried out at seven sites, six in the Toronto-Barrie Area and one at Thunder Bay, Ontario. The soil conditions included very dense till, soft clay up to 130 ft (39.62 m) in depth, dense sand and gravel and loose to compact silty sand. The test installations included both power installed multi-helix anchors and grouted anchors with a single reinforcing rod. These were installed at various depths. In the very deep clay only multi-helix anchors were tested. Most of the tests were in uplift on anchors installed vertically. A few group tests were conducted both in uplift and compression. The results of all of the tests are presented along with fairly detailed information on the properties of the soil at each site. An attempt to analyze the results of the helix anchor tests using simplified bearing theory was made. The grouted anchor tests were analyzed using either frictional or adhesive bond theory depending on the soil type. The results indicate that the theories using conventional soil properties provide reasonable design parameters for initial planning. Further confirmation by fullscale testing, however, is essential.
Microstructure of a Laboratory Sedimented Flocculated Illitic Sediment
Authors: O'Brien Neal R.
Published: February 2009

Scanning electron microscope study of the fabric of air dried laboratory sedimented flocculated illite reveals a network of randomly oriented flakes or groups of flakes. The author hopes the results will provide a useful point of reference in considering fabric changes induced in consolidated clays.
Slope stability investigation at Gaspé copper mines
Authors: Hucka V. J. , Levaque J. G. , Allard M.
Published: February 2009

In view of the extensive open pit mining operation at Gaspé Copper Mines Limited, Murdochville, Quebec, a study of an optimum slope design was felt necessary. This paper describes the different steps of the slope stability project: origin and organization to achieve an optimum design. The various phases of the project were: survey of the ore body and topography, investigation of physico-mechanical properties of rocks, structural geological mapping, groundwater study, and detailed study of structural weaknesses. The results were subsequently used to analyse different modes of possible failure of rock mass. The information obtained is being used in redesigning the Copper Mountain pit.
A fluoride borehole dilution apparatus for groundwater velocity measurements
Authors: Grisak G. E. , Merritt W. F. , Williams D. W.
Published: February 2009

A borehole dilution method using fluoride in low concentrations as the tracer and an adapted, commercially available fluoride ion electrode to measure the tracer dilution has been developed and employed at two sites. The sites are shallow groundwater systems consisting of alluvial surficial gravels near Fort Macleod, Alberta, and glaciodeltaic sand deposits at the Chalk River Nuclear Laboratories, Ontario. Zones of relatively high groundwater velocities determined at Fort Macleod with the fluoride apparatus are also evident in the results of a large-scale tracer test that documented chloride profiles over the saturated gravel thickness from point samples at 0.3 m depth intervals. The performance of the fluoride electrode compared favorably with a radio tracer (131I) technique in a simultaneous dilution experiment at the Chalk River site. Other ion-selective electrodes such as the chloride electrode may provide an alternative sensor in areas where hydrochemical conditions may restrict the use of the fluoride electrode.
Estimation of some properties of Champlain clays with the Swedish fall cone
Authors: Garneau R. , LeBihan J. P.
Published: February 2009

A large number of laboratory tests, carried out to determine index and physical characteristics of Champlain marine clays, using conventional testing procedures and the Swedish fall cone tests, have led to reliable relationships between the cone penetration and certain characteristics.The purpose of this study has been to establish a rapid method of estimating some index and physical characteristics of this clay. The method described in this paper allows the estimation of clay properties, such as liquid limit, compression index, preconsolidation pressure, undisturbed and remolded shear strength, sensitivity, water content, void ratio, and unit weight, within as little as half an hour and using a single undisturbed specimen. When testing according to conventional procedures, the determination of these characteristics takes several days or even weeks.This paper presents the method of estimation and the procedure used to establish the relationships between the results obtained by conventional methods and those derived using the Swedish fall cone.
Effect of forest floor disturbance on seedling establishment of Chamaecyparislawsoniana
Authors: Zobel Donald B.
Published: February 2009

Native seeds of Chamaecyparislawsoniana (A. Murr.) Parl. (Port-Orford-cedar) were sown on treated 1-m2 plots in four natural stands in southwestern Oregon, U.S.A. Treatments, replicated four times per stand, were (1) control, with natural litter undis-turbed, (2) litter removed, (3) litter removed and burned with ash replaced on plot, and (4) spaded after litter removal. Eighty-nine percent of germination occurred in early to mid-June. The spading treatment had the most germinants and the most survivors. Litter removal and burning treatments supported many fewer germinants, had the smallest seedlings, and had no survival after two growing seasons. Percentage survival of the few germinants in the control was as good as for the spading treatment, 5–6% after three summers. Although much natural seedling establishment may occur on natural litter, soil disturbance appears to greatly increase the rate of establishment. Litter removal alone does not increase establishment.
Use of dummy variables to harmonize tree biomass tables
Authors: Jacobs M. W. , Cunia T.
Published: February 2009

When constructing biomass tables for various tree components, it is often necessary to force their regression functions to be similar in shape and consistent in spacing. A procedure using dummy variables is presented for the harmonization of the regression functions of the biomass of the tree bole up to various top diameters. The procedure allows one to calculate several regressions simultaneously to test their similarity, control their spacing, and compare statistically various regression models.
Dimension analysis of various components of black spruce in subarctic lichen woodland
Authors: Rencz Andrew N. , Auclair Allan N.
Published: February 2009

Parabolic and logarithmic regressions were used to relate tree diameter to the biomass of root, root crown, bole, branch, needle, cone, and epiphytic lichens for a sample of 15 Piceamariana (Mill) trees occupying lichen woodland in the subarctic of eastern Canada. In 22 of 27 regressions both models yielded r2 values >0.82. Biomass estimates of total tree and individual component dry weights resulted in estimates with less than 6.5% difference between biomass estimates by logarithmic versus parabolic equations. For this data set the logarithmic model appeared more appropriate than the parabolic form. Validity of the regressions was judged on r2, analysis of variance, and examination of residuals. Equations generated in this study were considered to be inapplicable to P. mariana growing in closed forest. Problems in extrapolation were discussed.