bluuebunny/crossref_metadata_2025 huggingface dataset:
DME-Fired Water-Tube Boiler: An R&D Study
Authors: Ozawa Mamoru , Matsumoto Ryosuke , Higuchi Nobuo , Hayashi Yoshio , Uematsu Hiroki , Suita Yoshitaka
Published: October 2008

Increasing attention has been given to the development of low-NOx combustion technology for DME (Dimethyl Ether). The present paper describes a R&D study for water-tube boiler carried out in Kansai University and Hirakawa Guidam Co. Ltd. under the support of DME project from METI. The main problem arisen in DME use is a difficulty in an application of premixed flame owing to low ignition temperature and rather high burning velocity. Then the previously developed tube-nested combustor, i.e. water-tubes are installed in the empty furnace, becomes effective means to overcome such difficulty in realizing low-NOx combustion. This paper begins with a brief review of R&D study of the tube-nested combustor specifically designed for city gas. Then further development for DME-fired water-tube boiler is described.
Operating Results of Phosphoric Acid Type 100kW Fuel Cell Co-Generation System
Authors: Kato Shigemi , Ohga Shunsuke
Published: October 2008

Fuji Electric Group has sold many 100kW phosphoric acid fuel cell (PAFC) generation systems. These PAFC systems have achieved the initial development goal of a cell life of 40,000 hours (approximately 5 years). The first set of second-commercial-type 100kW PAFC (FP-100F) has been operated since December 2001 at a training institute of Fuji Electric Human Resources Development Center Co., Ltd. The facility has introduced a new energy generation system composed with a 100kW PAFC, a 26kW micro gas turbine and a 10kW photovoltaic generation. This new energy generation system aims to save energy with mainly use PAFC for supplying electrical power, and micro gas turbine for heat demand. This system has been achieved to reduce CO2 emissions of 30%, and to save energy of 13% during December 2001 to March 2004, compared with conventional commercial electric power and a boiler.
Development of New Heat Supply Unit Using Latent Heat: Dynamic Characteristics of Heat Storage Unit by a Use of Plate Fin Type Heat Exchanger
Authors: Asano Hitoshi , Fujii Terushige , Hisazumi Yoshinori , Hori Toshihiro , Abiko Tetsuo , Kubokawa Seiichi
Published: October 2008

A high efficient co-generation system named “Neighboring Communities Co-generation System” is proposed to a multiple dwelling house. The key technology of this system is to connect home and home with one loop of heat transfer line of one-inch diameter, and to level the heat demand by a heat storage unit in each house. This system requires a compact heat storage unit of quick response. In this study, a plate fin type brazing heat exchanger was built and tested as the heat storage unit. Sodium acetate trihydrate with a melting point of about 58 °C and a paraffin wax with a higher value of 74.8 °C were used as the phase change material (PCM). As a result, it was shown that the heat transfer in the heat storage unit was dominated by thermal conductivity in PCM. The paraffin wax showed higher responsibility and higher heat output due to its higher melting point and quite lower super cooling in solidification.
Effect of H2S on MCFC 10kW-Stack Performance
Authors: Morita H. , Kawase M. , Izaki Y. , Komoda M. , Matsuyama T.
Published: October 2008

The conversion of coal, biomass and RDF (refuse-derived fuel) etc, by means of gasification into a fuel suitable for a high temperature fuel cell has recently received more attention as a potential substitute for fossil fuels in electric power production. However, combining the gasification with a high temperature fuel cell (Molten Carbonate Fuel Cell) raises many questions with regard to gas quality and impurities. We have paid attention to H2S impurity contained in fuel gas and investigated the effect of H2S on MCFC performance by operating a 10kW-class stack. The experimental results show the H2S tolerable concentration to MCFC performance decreases with the decrease of H2 concentration in fuel gas. A reason for this H2S tolerance is due to the inhibition for shift reaction (H2O + CO → H2 + CO2) by H2S adsorption to anode. This inhibition by H2S adsorption decreases the capability of high temperature fuel cell to utilize CO as a fuel.
New Concept of a Micro Gas Turbine Based Co-Generation Package for Performance Improvement in Practical Use
Authors: Mochizuki Kenichiro , Shibata Satoshi , Inoue Umeo , Tsuchiya Toshiaki , Sotouchi Hiroko , Okamoto Masanori
Published: October 2008

As the energy consumption has been increasing rapidly in the commercial sector in Japan, the market potential for the micro gas turbine is significant and it will be realized substantially if the thermal efficiency is improved. One of measures is to introduce the steam injection system using the steam generated by the heat recovery steam generator. Steam injection tests have been carried out using a micro gas turbine (Capstone C60). Test results showed that key performance parameters such as power output, thermal efficiency and emissions were improved by the steam injection. The stable operation of micro gas turbine with steam injection was confirmed under various operating conditions. Consequently, a micro gas turbine based co-generation package with steam injection driven by a heat recovery steam generator (HRSG) with supplementary firing is proposed.
New Developments in High Temperature Materials 21 Project in Japan
Authors: Harada Hiroshi , Fujioka Junzo
Published: October 2008

Following the Kyoto Conference on Climate Change (COP3) held in 1997, the improvement of thermal efficiency in power engineering systems is becoming a major issue. In High Temperature Materials 21 Project at NIMS, materials for turbine blades and vanes are being developed to improve the temperature capability and reduce the CO2 emission of industrial gas turbines (IGT) and jet engines. The target for Ni-base superalloys was set at 1100°C for 1000h creep rupture life under 137MPa to realize ultra-efficient combined cycle power plants and advanced jet engines. A high cost-performance single crystal (SC) superalloy TMS-82+ with 1075°C temperature capability has been developed and tested in a 15MW IGT. A 4th generation SC superalloy TMS-138 exhibiting 1080°C temperature capability has also been developed and tested in a 1650°C test jet engine. TMS-138 is to be applied in the Japanese eco-engine project for 50-seater jet airplanes. A further control of the interfacial dislocation network resulted in a 5th generation SC alloy TMS-162 with 1105°C temperature capability. A virtual gas turbine (VT), which is a combination of materials design program and system design program, is being developed and becoming a powerful tool as an interface between material scientists and system engineers. Using VT, air-cooled blades with our SC superalloys have been evaluated up to 1700°C gas temperature, and a substantial improvement in thermal efficiency of a combined-cycle power generation system has been indicated.
Numerical Simulation of Molten-Slag Flow in Coal Gasifier
Authors: Otaka Maromu , Watanabe Hiroaki , Hara Saburo
Published: October 2008

In this paper, numerical simulations of the heat transfer in molten-slag flow with free surface and phase change (solidification) is carried out, and we propose a new evaluation method for discharging performance of the molten-slag from coal gasifier. A stable operation of the coal gasifier requires that the molten-slag should be discharged from the slag-hole continuously. In the maintenance of discharging a molten slag, it is necessary to keep the molten-slag temperature higher than an ash fluid temperature, and to hold the fluidity of the molten-slag. From the viewpoint of gasification performance, if the air ratio is set low in order to raise the cold gas efficiency, the molten-slag is not able to get enough heat for its discharge, because of the lowering of gas temperature in the coal gasifier. To strike a balance between the maintenance of continuity on the molten-slag discharge and the improvement in gasification performance, it is important to develop a prediction and evaluation method for discharge performance of the molten-slag from coal gasifier.
An Optimal Renewal Planning of Energy Supply System From Economic Viewpoint
Authors: Yoshida Shu , Gamou Satoshi , Ito Koichi , Enokido Toshinori , Yokoyama Ryohei
Published: October 2008

An optimal planning method of renewal planning for energy supply systems is proposed to determine the proper renewal year and selection as to what kind of equipment is suitable for several types of buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the annual total cost in consideration of system’s annual operational strategies corresponding to seasonal and hourly energy demand requirements during every evaluation year considered. A numerical study is carried out for an office building with a total floor area of 15 000m2, where the system is consisted of an electric refrigerator and a steam boiler. Through the numerical calculation, the influence of the following items are clarified on the optimal renewing year and selection of renewing equipment of the system by the parametric study; (a) upgrading technology of the equipment in the future; (b) initial capital cost of equipment; (c) renewing construction cost and trade-in value rate; and (d) interest rate.
Development of Single Loop Heat Supply System for Local Community Cogeneration: Prototype Test of a Heat Supply Unit With Heat Storage and Tap Water Preheating by Heat Pump Unit
Authors: Asano Hitoshi , Fujii Terushige , Hisazumi Yoshinori , Hori Toshihiro , Abiko Tetsuo
Published: October 2008

In order for economically viable distributed generation systems for local community to spread, it is essential to develop an efficient and low-cost heat supply system. We propose a new heat supply system called DREAMS (Distributed Residential Energy with Advanced Management System). The key technology for the system is to connect compact heat supply units installed in all the households of the local community, such as a condominium, by a single loop of hot water piping. Two methods to decrease the heat supply rate through the single loop are proposed in this paper. The one is an utilization of a compact heat supply unit with heat storage in each house. The momentary heat demand can be covered by the heat storage. The other is a tap water preheating. A new CO2 regenerative heat pump cycle was proposed for the recover of the low temperature heat from the generator. A new heat supply unit with a practical capacity was manufactured, and the heat supply performance was evaluated by some experiments. Furthermore, an advanced energy management system has been under consideration to realize the effective system operation by utilizing IT. In this paper, experimental results on the performance of the new heat supply unit, the new CO2 heat pump system and evaluation of the energy-saving effect of our DREAMS are presented.
Study on Optimal Operational Planning of Advanced Co-Generation System in Consideration of Annual Demand Analysis
Authors: Tomizawa Masao , Takeshita Keisuke , Akita Tatsuhiro , Amano Yoshiharu , Hashizume Takumi
Published: October 2008

This paper presents the optimal plan in an assumed cogeneration system based on Advanced Co-generation system built in Kikui-cho campus and suggests the introductory technique of co-generation system. At first, we analyzed the annual change of the electric power and cooling demand for a typical consumer and completed the assumed model by formulating. In hospital, hotel, etc., it was checked that electric power and cooling demand have the high correlation with outside temperature, and the daily maximum temperature is effective as an explaining variable especially. We verified the optimal planning according to the consumer using this assumed demand.
Novel Chimeric β-Lactamase CTX-M-64, a Hybrid of CTX-M-15-Like and CTX-M-14 β-Lactamases, Found in a
Shigella sonnei
Strain Resistant to Various Oxyimino-Cephalosporins, Including Ceftazidime
Authors: Nagano Yukiko , Nagano Noriyuki , Wachino Jun-ichi , Ishikawa Keiko , Arakawa Yoshichika
Published: October 2008

The plasmid-mediated novel β-lactamase CTX-M-64 was first identified in
Shigella sonnei
strain UIH-1, which exhibited resistance to cefotaxime (MIC, 1,024 μg/ml) and ceftazidime (MIC, 32 μg/ml). The amino acid sequence of CTX-M-64 showed a chimeric structure of a CTX-M-15-like β-lactamase (N- and C-terminal moieties) and a CTX-M-14-like β-lactamase (central portion, amino acids 63 to 226), suggesting that it originated by homologous recombination between the corresponding genes. The introduction of a recombinant plasmid carrying
bla
CTX-M-64
conferred resistance to cefotaxime in
Escherichia coli
, and the activities of cefotaxime and ceftazidime were restored in the presence of clavulanic acid. Of note, CTX-M-64 production could also confer consistent resistance to ceftazidime, which differs from the majority of CTX-M-type enzymes, which poorly hydrolyze ceftazidime. These results were consistent with the kinetic parameters determined with the purified CTX-M-64 enzyme. The
bla
CTX-M-64
gene was flanked upstream by an IS
Ecp1
sequence and downstream by an
orf477
sequence. The sequence of the 45-bp spacer region between the right inverted repeat (IRR) of IS
Ecp1
and
bla
CTX-M-64
was exactly identical to that of IS
Ecp1
-
bla
CTX-M-15-like
. Moreover, the presence of a putative IRR of IS
Ecp1
at the right end of truncated
orf477
is indicative of an IS
Ecp1
-mediated transposition event in the
bla
CTX-M-64
gene. The emergence of CTX-M-64 by probable homologous recombination would suggest the natural potential of an alternative mechanism for the diversification of CTX-M-type β-lactamases.
Optimized Elution of Daptomycin from Polymethylmethacrylate Beads
Authors: Weiss Brian D. , Weiss Elizabeth C. , Haggard Warren O. , Evans Richard P. , McLaren Sandra G. , Smeltzer Mark S.
Published: October 2008

We demonstrate that xylitol can be added to polymethylmethacrylate (PMMA) bone cement to enhance the elution of daptomycin in terms of both the peak and sustained release of antibiotic. We also demonstrate that a PMMA-xylitol formulation optimized for daptomycin can be used to enhance the elution of both vancomycin and gentamicin.
Genotypic versus Phenotypic Characterization, with Respect to β-Lactam Susceptibility, of
Haemophilus influenzae
Isolates Exhibiting Decreased Susceptibility to β-Lactam Resistance Markers
Authors: Sevillano David , Giménez María-José , Cercenado Emilia , Cafini Fabio , Gené Amadeo , Alou Luis , Marco Francesc , Martínez-Martínez Luis , Coronel Pilar , Aguilar Lorenzo
Published: October 2008

Among 165 Spanish
Haemophilus influenzae
isolates with mutations in the
ftsI
gene (
ftsI

+

) (2005 to 2007), 73% were β-lactamase negative and 26.7% were positive. The proportion of β-lactamase-negative isolates to β-lactamase-positive isolates was 2:1 to 4:1 in general, versus 1:3 in pediatric hospitals. Among 44 β-lactamase-positive strains, 8 strains produced ROB-1 (5 from the pediatric hospital). β-Lactamase-positive
ftsI

+

strains were phylogenetically closer than were β-lactamase-negative strains.
Tissue Accumulation of Cephalothin in Burns: a Comparative Study by Microdialysis of Subcutaneous Interstitial Fluid Cephalothin Concentrations in Burn Patients and Healthy Volunteers
Authors: Dalley Andrew J. , Lipman Jeffrey , Deans Renae , Venkatesh Bala , Rudd Michael , Roberts Michael S. , Cross Sheree E.
Published: October 2008

Burn tissue sites are a potential source of bacteremia during debridement surgery. Burn injury is likely to affect the distribution of antibiotics to tissues, but direct evidence of this is lacking. The aim of this study was to directly evaluate the influence of burn trauma on the distribution of cephalothin to peripheral tissues. We used subcutaneous microdialysis techniques to monitor interstitial fluid concentrations of cephalothin in the burnt and nonburnt tissues of adult patients with severe burns following parenteral administration of 1 g cephalothin for surgical prophylaxis. Analogous simultaneous studies conducted with healthy adult volunteers provided reference tissue concentration data. Equivalent tissue exposures were seen for burn and nonburn sites, giving overall median interstitial cephalothin concentrations (from 0 to 240 min) of 2.84 mg/liter and 3.06 mg/liter, respectively. A lower overall median interstitial cephalothin concentration of 0.54 mg/liter was observed for healthy individuals, and the patient nonburnt tissue and volunteer control tissue cephalothin concentrations exhibited significantly different data distributions (
P
< 0.001; Kolmogorov-Smirnov nonparametric test). The duration of tissue residence for cephalothin was longer for burn patients than for healthy volunteers. The results demonstrate the potential fallibility of using healthy population models to extrapolate tissue pharmacodynamic predictions from plasma data for burn patients.
Pharmacokinetics of BILR 355 after Multiple Oral Doses Coadministered with a Low Dose of Ritonavir
Authors: Huang Fenglei , Drda Kristin , MacGregor Thomas R. , Scherer Joseph , Rowland Lois , Nguyen Thuy , Ballow Charles , Castles Mark , Robinson Patrick
Published: October 2008

The pharmacokinetics and safety of BILR 355 following oral repeated dosing coadministered with low doses of ritonavir (RTV) were investigated in 12 cohorts of healthy male volunteers with a ratio of 6 to 2 for BILR 355 versus the placebo. BILR 355 was given once a day (QD) coadministered with 100 mg RTV (BILR 355/r) at 5 to 50 mg in a polyethylene glycol solution or at 50 to 250 mg as tablets. BILR 355 tablets were also dosed at 150 mg twice a day (BID) coadministered with 100 mg RTV QD or BID. Following oral dosing, BILR 355 was rapidly absorbed, with the mean time to maximum concentration of drug in serum reached within 1.3 to 5 h and a mean half-life of 16 to 20 h. BILR 355 exhibited an approximately linear pharmacokinetics for doses of 5 to 50 mg when given as a solution; in contrast, when given as tablets, BILR 355 displayed a dose-proportional pharmacokinetics, with a dose range of 50 to 100 mg; from 100 to 150 mg, a slightly downward nonlinear pharmacokinetics occurred. The exposure to BILR 355 was maximized at 150 mg and higher due to a saturated dissolution/absorption process. After oral dosing of BILR 355/r, 150/100 mg BID, the values for the maximum concentration of drug in plasma at steady state, the area under the concentration-time curve from 0 to the dose interval at steady state, and the minimum concentration of drug in serum at steady state were 1,500 ng/ml, 12,500 h·ng/ml, and 570 ng/ml, respectively, providing sufficient suppressive concentration toward human immunodeficiency virus type 1. Based on pharmacokinetic modeling along with the in vitro virologic data, several BILR 355 doses were selected for phase II trials using Monte Carlo simulations. Throughout the study, BILR 355 was safe and well tolerated.
Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in
Escherichia coli
,
Klebsiella pneumoniae
, and
Proteus mirabilis
Authors: Tan Thean Yen , Ng Lily Siew Yong , He Jie , Koh Tse Hsien , Hsu Li Yang
Published: October 2008

There are currently no standardized phenotypic methods for the screening and detection of AmpC enzymes. This study aimed to evaluate different methods to detect AmpC enzymes in
Escherichia coli
,
Klebsiella
spp., and
Proteus
spp., comparing the results from two disk-based methods and an agar dilution method. AmpC activity was determined for 255 clinical isolates by use of a three-dimensional enzyme assay combined with a multiplex PCR assay for plasmid-borne
ampC
genes. These results were compared against a disk-based inhibitor assay using various combinations of cefpodoxime and cefoxitin as antibiotic substrates and boronic acid or cloxacillin as an AmpC inhibitor. The presence of enzyme induction by disk approximation was evaluated using imipenem, cefoxitin, and amoxicillin-clavulanate as inducing agents against ceftazidime. Finally, an agar dilution assay was performed, using cefoxitin with and without added cloxacillin. AmpC activity was present in 49.8% of test isolates, 93.7% of which were positive for plasmid-borne
ampC
genes. CIT-like enzymes were predominant in
E. coli
, and DHA-like enzymes were predominant in
Klebsiella
spp. The disk-based inhibitor tests performed better than the agar dilution assay, while detection of AmpC by disk induction had a poor sensitivity. The cefoxitin-cloxacillin disk combination provided the best overall performance, with a sensitivity and specificity of 95%. This study confirmed the accuracy of disk-based inhibitor screening for AmpC enzymes, which proved reliable at detecting CIT- and DHA-like plasmid-borne
ampC
genes. The methods are simple enough for introduction into clinical microbiology laboratories.
Activity of T-705 in a Hamster Model of Yellow Fever Virus Infection in Comparison with That of a Chemically Related Compound, T-1106
Authors: Julander Justin G. , Shafer Kristiina , Smee Donald F. , Morrey John D. , Furuta Yousuke
Published: October 2008

Treatment with the nucleoside analog T-1106 was previously shown to be effective in a hamster model of yellow fever virus (YFV) disease, even though it had only slight activity in cell culture. In the study described in this report, the activity of T-705, a chemically related compound currently undergoing clinical trials for the treatment of influenza (FDANews 4:1, 2007), was tested against YFV in cell culture and in the hamster model. The antiviral efficacy of T-705 in cell culture occurred at a concentration of 330 μM, which was more than threefold lower than the concentration at which T-1106 had antiviral efficacy, as determined by a virus yield reduction assay and confirmed by a luciferase-based ATP detection assay. Time-of-addition studies revealed that addition of T-705, T-1106, or ribavirin at 0, 4, 8, or 12 h after virus challenge was effective in inhibiting virus in Vero cells, suggesting that these three agents have similar mechanisms of action in cell culture. Because of its more potent activity in cell culture, it was anticipated that T-705 treatment of hamsters infected with YFV would result in protection from disease. Significant improvements in survival and disease parameters were seen in infected animals when T-705 was administered orally at a dose of 200 or 400 mg/kg of body weight per day when it was given twice a day for 8 days. Significant improvements were also observed with a dose of 400 mg/kg/day when treatment initiation was delayed as late as 3 days after virus inoculation. Although the dose of T-705 required for efficacy in hamsters is higher than that of T-1106 required for efficacy, T-705 treatment is effective in significantly improving disease parameters in YFV-infected hamsters, which may indicate its potential utility in the treatment of YFV disease in humans.
Chloroquine Is Grossly Overdosed and Overused but Well Tolerated in Guinea-Bissau
Authors: Ursing Johan , Kofoed Poul-Erik , Rodrigues Amabelia , Bergqvist Yngve , Rombo Lars
Published: October 2008

High chloroquine doses are commonly prescribed in Guinea-Bissau. Double-dose chloroquine has been shown to be more efficacious (92% efficacy) than the standard dose (80% efficacy). However, chloroquine is toxic when overdosed, and it was not known if the high doses prescribed in Guinea-Bissau were taken or whether they caused adverse effects. We aimed to determine the dosage of chloroquine commonly prescribed, the doses commonly taken, and whether concentration-dependent adverse events occurred in routine practice. Chloroquine prescriptions by eight physicians and chloroquine intake by 102 children were recorded. Chloroquine intake and adverse events were assessed by questioning. Chloroquine concentrations in whole blood were measured. The median total chloroquine dose prescribed and that reportedly taken were 81 and 77 mg kg
−1
, respectively. The total dose was usually split into two to three daily doses of 6.6 mg kg
−1
each. These were taken unsupervised for a median of 5 days. Forty percent of the study children had chloroquine concentrations in the same range as those found in a previous study in which double the normal dose (50 mg kg
−1
) of chloroquine was taken. Only 3/102 children had
Plasmodium falciparum
in the blood at the time of diagnosis and treatment. No severe adverse events were reported. No adverse events were associated with higher chloroquine concentrations. High doses of chloroquine are commonly taken and well tolerated in Guinea-Bissau. Malaria diagnostics are poor, and chloroquine is commonly prescribed to children without parasitemia. Use of high-dose chloroquine is concurrent with an exceptionally low prevalence of chloroquine-resistant
P. falciparum
.
Antifungal Susceptibilities among Different Serotypes of
Cryptococcus gattii
and
Cryptococcus neoformans
Authors: Thompson George R. , Wiederhold Nathan P. , Fothergill Annette W. , Vallor Ana C. , Wickes Brian L. , Patterson Thomas F.
Published: October 2008

We measured antifungal activity against 128 cryptococcal isolates (86 of
C. neoformans
and 42 of
C. gattii
) to determine if differences in serotype susceptibility exist. Contrary to previous results, we found no serotype susceptibility differences. Isavuconazole, posaconazole, and voriconazole demonstrated excellent potency against each isolate and serotype, including isolates with reduced fluconazole susceptibilities.
Susceptibility of
Mycobacterium bovis
BCG Vaccine Strains to Antituberculous Antibiotics
Authors: Ritz Nicole , Tebruegge Marc , Connell Tom G. , Sievers Aina , Robins-Browne Roy , Curtis Nigel
Published: October 2008

Mycobacterium bovis
BCG is one of the most commonly administered vaccines. Complications, including disseminated BCG disease, are rare but increasingly reported in immunodeficient children. There is growing recognition of the importance of differences between BCG vaccine strains. We determined the susceptibilities of five genetically distinct BCG vaccine strains to 12 antituberculous drugs.
Staphylococcus aureus
Rbf Activates Biofilm Formation In Vitro and Promotes Virulence in a Murine Foreign Body Infection Model
Authors: Luong Thanh T. , Lei Mei G. , Lee Chia Y.
Published: October 2008

We previously identified Rbf as an activator for biofilm formation on polystyrene surfaces in
Staphylococcus aureus
strain 8325-4. However, strain 8325-4 contains genetic mutations that may affect biofilm formation. To extend the observation to other strains, we used strain Newman, a weak biofilm producer, and strain UAMS-1, an osteomyelitis clinical strain, in this study. We found that mutations in the chromosomal
rbf
gene did not affect biofilm formation on polystyrene surfaces in these strains, but transformants of these strains carrying a multiple-copy plasmid containing the
rbf
gene formed stronger biofilms than the wild-type strains and the mutant strains. Using the flow cell method, we found that the chromosomal mutation in the
rbf
gene delayed biofilm formation, whereas strains with a plasmid containing the
rbf
gene accelerated biofilm formation in strains Newman and UAMS-1. These results led us to conclude that
rbf
is an activator of biofilm formation in different strains of
S. aureus
, although the degree of activation varies among strains. In a murine model of foreign body infection, the
rbf
mutations in strain Newman, but not in strain UAMS-1, reduced the bacterial survival rate in catheter lumen. However, UAMS-1 carrying multiple copies of
rbf
in a plasmid increased the bacterial survival rate. The animal studies therefore suggest that Rbf has a role in
S. aureus
virulence.
Genome-Wide Screen in
Francisella novicida
for Genes Required for Pulmonary and Systemic Infection in Mice
Authors: Kraemer Petra S. , Mitchell Allison , Pelletier Mark R. , Gallagher Larry A. , Wasnick Mike , Rohmer Laurence , Brittnacher Mitchell J. , Manoil Colin , Skerett Shawn J. , Salama Nina R.
Published: October 2008

Francisella tularensis
is a gram-negative, highly infectious, aerosolizable facultative intracellular pathogen that causes the potentially life-threatening disease tularemia. To date there is no approved vaccine available, and little is known about the molecular mechanisms important for infection, survival, and dissemination at different times of infection. We report the first whole-genome screen using an inhalation mouse model to monitor infection in the lung and dissemination to the liver and spleen. We queried a comprehensive library of 2,998 sequence-defined transposon insertion mutants in
Francisella novicida
strain U112 using a microarray-based negative-selection screen. We were able to track the behavior of 1,029 annotated genes, equivalent to a detection rate of 75% and corresponding to ∼57% of the entire
F. novicida
genome. As expected, most transposon mutants retained the ability to colonize, but 125 candidate virulence genes (12%) could not be detected in at least one of the three organs. They fell into a variety of functional categories, with one-third having no annotated function and a statistically significant enrichment of genes involved in transcription. Based on the observation that behavior during complex pool infections correlated with the degree of attenuation during single-strain infection we identified nine genes expected to strongly contribute to infection. These included two genes, those for ATP synthase C (FTN_1645) and thioredoxin (FTN_1415), that when mutated allowed increased host survival and conferred protection in vaccination experiments.
Multiple Functional Domains of
Enterococcus faecalis
Aggregation Substance Asc10 Contribute to Endocarditis Virulence
Authors: Chuang Olivia N. , Schlievert Patrick M. , Wells Carol L. , Manias Dawn A. , Tripp Timothy J. , Dunny Gary M.
Published: October 2008

Aggregation substance proteins encoded by sex pheromone plasmids increase the virulence of
Enterococcus faecalis
in experimental pathogenesis models, including infectious endocarditis models. These large surface proteins may contain multiple functional domains involved in various interactions with other bacterial cells and with the mammalian host. Aggregation substance Asc10, encoded by plasmid pCF10, is induced during growth in the mammalian bloodstream, and pCF10 carriage gives
E. faecalis
a significant selective advantage in this environment. We employed a rabbit model to investigate the role of various functional domains of Asc10 in endocarditis. The data suggested that the bacterial load of the infected tissue was the best indicator of virulence. Isogenic strains carrying either no plasmid, wild-type pCF10, a pCF10 derivative with an in-frame deletion of the
prgB
gene encoding Asc10, or pCF10 derivatives expressing other alleles of
prgB
were examined in this model. Previously identified aggregation domains contributed to the virulence associated with the wild-type protein, and a strain expressing an Asc10 derivative in which glycine residues in two RGD motifs were changed to alanine residues showed the greatest reduction in virulence. Remarkably, this strain and the strain carrying the pCF10 derivative with the in-frame deletion of
prgB
were both significantly less virulent than an isogenic plasmid-free strain. The data demonstrate that multiple functional domains are important in Asc10-mediated interactions with the host during the course of experimental endocarditis and that in the absence of a functional
prgB
gene, pCF10 carriage is actually disadvantageous in vivo.
Identification et distribution des grandes masses d'eau dans les mers du Labrador et d'Irminger
Authors: Lucotte Marc , Hillaire-Marcel Claude
Published: October 2008

The main deep water masses present at the time of the CSS Hudson cruises in Labrador and Irminger seas in June 1990 and October–November 1991 have been identified using characteristic temperatures (T) and salinities (S). The purpose of this study was to establish the transfer functions between micropaleontological assemblages of top sediments and thermohaline characteristics of water masses. The water mass at the top of the Labrador Sea (Labrador Sea Water, LSW) is formed after intense movements of winter convection in the first 900-m depth of the water column. Below that depth, the LSW parameters reach a double minimum (S ≈ 34.80 and T ≈ 2.9 °C). Only the sediments located on the continental slopes of Greenland and Labrador between depths of 500 and 1500 m are in contact with the LSW. Below the LSW, the superior fraction of the North East Atlantic Deep Water (NEADW1) is characterized by a temperature maximum (≈ 3.3 °C) and, as such, is distinguishable from the inferior fraction (NEADW2). The latter is characterized by a maximum S (≈ 34, 90) when compared with other intermediary and deep water masses. In contrast to the NEADW1 that freely circulates over the Reykjanes Ridge, the NEADW2 must flow through the Charlie Gibbs Fracture Zone to go from the northeastern Atlantic to the Irminger Sea. The NEADW 1 and 2 respectively bathe the ridge section less than 2000 m deep and the European abyssal basins. On the contrary, the majority of the deep sediments of the Labrador and Irminger seas are in contact with the cold (T < 2.6 °C) and salty (≈ 34.85) Denmark Strait Overflow Water. Although this water mass is normally found at depths exceeding 2700 m in pelagic environments, it can be found at less than 2000-m depth on the bottom of the continental slopes of Greenland and Labrador, where it is carried by the strong Deep Northern Boundary Current and Western Boundary Undercurrent. The presence of the NEADW 1 and 2 on the sediments is then restricted to narrow bands on the same continental slopes, between depths of 1800 and 2200 m.
Sediments, sedimentation rates, and environments, southeast Baffin Shelf and northwest Labrador Sea, 8–26 ka
Authors: Andrews J. T. , Tedesco K. , Briggs W. M. , Evans L. W.
Published: October 2008

Ten 14C-dated cores are described from the Labrador Sea, continental slope, and Hatton and Resolution basins on the southeast Baffin Shelf. Based on sharply defined detrital carbonate layers in the Labrador Sea cores, we propose that the Laurentide Ice Sheet reached the shelf break at both 20 and 15 14C ka (24.3 and 18.2 sidereal ka) and contributed significant sediment to the northwest Labrador Sea both times; the flux was ± 720 kg/(m2∙ka) during these periods of maximum ice extent. The Laurentide Ice Sheet retreated from its 15 ka position at the shelf break to the inner shelf between 14 and 12 14C ka. Ice-proximal conditions, recognized by relatively light δ18O on near-surface planktonic foraminifera, high detrital carbonate, and benthic foraminiferal faunas (dominated by Elphidium excavatum forma clavata; Cassidulina reniforme), prevailed until at least 10 14C ka. The ice readvanced toward Resolution Basin and across part of Hatton Basin at 11 14C ka. Accelerator mass spectrometry dates on core tops indicate that deposition on the shelf virtually ceased by 7 ka and was very low in the northwest Labrador Sea throughout the Holocene. Downcore accelerator mass spectrometry dates indicate that during deglaciation, the loci of depocentres shifted in response to changes in the position of the ice margin. On the southeast Baffin Island shelf net sediment fluxes at the sea floor reached values of over 3000 kg/(m2∙ka) between 12 and 10 14C ka, of which nearly half was detrital carbonate, principally calcite.
High-resolution rock magnetic study of a Late Pleistocene core from the Labrador Sea
Authors: Stoner Joseph S. , Channell James E. T. , Hillaire-Marcel Claude , Mareschal Jean-Claude
Published: October 2008

A high-resolution rock magnetic study of a Late Pleistocene core from the Labrador Sea, north of the Eirik Ridge on the Greenland rise, reveals three main features in the downcore variation of the rock magnetic parameters. Two are at the glacial–interglacial transitions (i.e., isotope stages 6–5e and 2–1), showing magnetic grain-size coarsening and increased magnetic concentration and accumulation. The magnetic grain-size coarsening and increased magnetic concentration associated with 6–5e transition and continuing into substage 5e are related to climatic influences. The magnetic grain-size coarsening and increased magnetic concentration and accumulation at the 2–1 transition appear to be climate related, although increased tephra concentrations may perturbate the record during this interval. Previous studies in this region have connected the coarsening of magnetic grain size during transitions to current winnowing of the finer fraction during interglacial conditions. The interpretation of the present study is that the coarsening is primarily due to increased detrital deposition related to ice retreat and the associated melt-water flux from southern Greenland. The third magnetic feature corresponds to the initial part of stage 2 where there is a distinct interval of higher coercivity. This high coercivity interval has no obvious correlation to climate change, but appears to be related to the increased preservation of ultrafine single domain ferrimagnetic material due to a lack of reduction diagenesis within this interval. The preservation of oxic conditions within this interval is indicated by a color change within the sediments.
Productivité et flux de carbone dans la mer du Labrador au cours des derniers 40 000 ans
Authors: Hillaire-Marcel Claude , Vernal Anne de , Lucotte Marc , Mucci Alfonso , Bilodeau Guy , Rochon André , Vallières Sylvain , Wu Guoping
Published: October 2008

Geochemical and micropaleontological analyses of Labrador Sea sediments allowed us to intercalibrate indicators of paleoproductivity and paleofluxes of carbon and to reconstitute biogeochemical fluxes, notably in relation to deep sea circulation changes (Western Boundary Undercurrent and North Atlantic Deep Water). Linear or logarithmic relations are observed between the subrecent fluxes of paleoproductivity indicators (coccoliths, diatoms, dinocysts, 230Th), the 13C content of left-coiling or sinistral Neogloboquadrina pachyderma, the modern surface water carbon production, and the rates of organic and inorganic carbon (Corg, Cinorg) burial. All indicators increase by a factor of 102 to 103 in response to the evolution of paleosea-surface conditions since the last glacial maximum. Correlations are observed between authigenic Cinorg, 230Th, coccoliths, and 13C content (left-coiling or sinistral Neogloboquadrina pachyderma), and also between authigenic Corg, dinocysts, uranium, and sulfur. Relative Cinorg/Corg burial rates in the deep sediments (> 3000 m) allow us to calculate a net CO2 production in the basin. The net CO2 flux was slightly negative between ~ 20 and ~ 15 ka BP. It reached a first maximum at about 9 ka BP (~ 30 μmol∙cm−2∙a−1 CO2) followed by a decrease at ~ 8 ka BP (~ 20 μmol∙cm−2∙a−1). Since about 7 ka BP, it stabilized at ~ 35 μmol∙cm−2∙a−1. The minimum observed at about 8 ka BP corresponds to a significant rate of Corg burial accompanied with a maximum flux of redox-sensitive indicators (uranium, sulfur). This event does not correspond to any change in sea-surface temperature or salinity, nor in deep circulation, but may be related to the reorganization of the atmospheric circulation during a major breakup stage of the Laurentide ice sheet. The close correlation between the change in CO2 production in the Labrador Sea with variations of atmospheric CO2 concentrations during the last 20 ka BP suggests that the production of biogenic carbonates in subpolar basins plays a role in the global carbon cycle on the scale of glacial–interglacial climate changes.
Deep crustal ductile extension following thrusting in the southwestern Grenville Province, Ontario
Authors: Culshaw N. G. , Ketchum J. W. F. , Wodicka N. , Wallace P.
Published: October 2008

Two lithotectonic assemblages in southern Britt domain have different histories of plutonism, metamorphism, structural development, and mafic dyke emplacement. These differences are accounted for by postulating that a cryptic Grenvillian thrust separates the assemblages. Amphibolite-facies extensional shear along the Central Britt shear zone (CBSZ) overprinted the thrust, obscuring kinematic evidence for its existence. The structurally lower Bayfield–Nadeau Island assemblage contains orthogneiss suites of disparate age, lesser amounts of supracrustal rocks deposited before intrusion of the youngest orthogneiss, pre-Grenvillian and Grenvillian metamorphic assemblages, and at least three mafic dyke suites. The overlying Ojibway – Sand Bay assemblage contains only younger orthogneiss with Grenvillian metamorphic assemblages, volumetrically important supracrustal rocks that are younger than the youngest orthogneiss, and lacks cross-cutting mafic dykes.Comparable tectono-stratigraphic changes are present across the thrust boundary separating the Ojibway – Sand Bay assemblage and the basal Parry Sound assemblage. Extensional shearing did not strongly overprint this boundary and it therefore serves as a relatively unmodified analogue of the overprinted boundary.Extension on the CBSZ overlapped formation of transverse ductile folds (hinges parallel to the extension–transport direction). These folds and the CBSZ dominate the crustal architecture at this level and are interpreted to be late orogenic structures formed during a gravity-assisted shape adjustment of the orogenic wedge. Thermal softening of the lower crust caused by thrust thickening may have allowed this to occur.
Detrital modes of the Riding Island Graywacke, north-central Newfoundland: evidence for deposition in a collisional successor basin in the Dunnage Zone
Authors: Lash Gary G.
Published: October 2008

The Riding Island Graywacke (late Caradoc – Ashgill) crops out in Notre Dame Bay, north-central Newfoundland. Previous tectonic interpretations suggest that this succession of turbidites and hemipelagic mudstone accumulated in a basin adjacent to an active volcanic arc. The varied framework mineralogy of 29 Riding Island samples studied, however, records derivation from a complex source terrane composed of mafic and silicic volcanic rocks, sedimentary and metamorphic successions, and plutonic rocks. Assessment of the tectonic environment of deposition of the Riding Island Graywacke by use of popular sandstone provenance ternary diagrams yields ambiguous results. The mineralogy of the Riding Island samples reveals a change in tectonic scenario from one dominated by island-arc volcanism in pre-Caradoc time to a setting marked by tectonic shortening, transcurrent faulting, and terrane accretion near the end of the Ordovician. The complex composition of these sandstones and the fact that they accumulated after island-arc volcanism had ended argue for deposition in a collisional successor basin that formed during the early stages of mountain building along the proto-North American continental margin. This inferred Late Ordovician collisional successor basin may have also been the locus of deposition for other minera-logically complex late Caradoc – Ashgill units exposed in Notre Dame Bay, such as the Sansom Formation.
Permafrost, tectonics, and past and future regional climate change, Yukon and adjacent Northwest Territories
Authors: Burn C. R.
Published: October 2008

Late Tertiary changes in the general circulation of the atmosphere, regionally enhanced by uplift of the Wrangell – Saint: Elias and Coast mountains, were sufficient to promote permafrost development in the western Arctic. Permafrost developed in Yukon Territory and adjacent Northwest Territories during early Pleistocene glacial periods, after continued tectonic activity led to further modification of regional climate, but degraded in the interglacials. Permafrost has been present in northern parts of the region since the Illinoian glaciation, but most ground ice in central Yukon formed in the Late Wisconsinan. The present interglacial is the only one with widespread evidence of permafrost, which is maintained in the valleys of central and southern Yukon by the Saint Elias Mountains blocking continental penetration of maritime air from the Gulf of Alaska. This reduces snow depth in winter, while cold-air drainage in the dissected terrain of the Yukon Plateaus enhances the near-surface inversion, leading to continental minimum temperatures. General circulation models used to simulate climate represent the physiography of northwest Canada crudely. As a result, the simulations are unable to reproduce conditions responsible for the development and preservation of permafrost in the region.
Deep seismic reflection data across the conjugate margins of the Labrador Sea
Authors: Keen C. E. , Potter P. , Srivastava S. P.
Published: October 2008

A deep seismic reflection transect of the conjugate margins of the Labrador Sea is described, which represents one of the few data sets of this kind. A characteristic reflectivity is ascribed to a 120 km wide ribbon of very thin crust that may be either thinned continental crust, which has perhaps been intruded, or oceanic crust, perhaps modified by the proximity of the continent. Most of the major changes in crustal thickness and in the subsidence and sedimentation patterns on the margins occur landward of these transitional zones, which are found on both margins. An interpretation of these regions as continental in origin is compatible with other seismic observations on the west Greenland margin, but does not match the magnetic anomaly interpretation, which requires the transitional crust to be oceanic in origin. Models that satisfy the gravity anomalies and the subsidence history have been used to assist in interpreting the seismic data. The subsidence models include the effects of decompression melting during lithospheric extension and rifting, and we predict the thickness of igneous crust produced. However, the gravity models suggest that a lower crustal layer may extend farther inland below the Labrador shelf than is predicted by magmatic underplating. The present seismic results, combined with the other geophysical data, are consistent with a pure shear model of lithospheric stretching, with faulting confined to the upper crust. Many of the problems raised by this data set are similar to those identified in comparing the nonvolcanic margin of Iberia with the conjugate Grand Banks margin in the North Atlantic. If the transition zone results from stretching the continental lithosphere, then a large component of the very thin crust there must consist of igneous material formed by melting. Under these conditions a sharp, vertical ocean–continent boundary would be unlikely.
The limits of computability
Authors: Lindley David
Published: October 2008

Computational complexity and intractability may help scientists better understand how humans process information and make decisions.
Analyzing online social networks
Authors: Howard Bill
Published: October 2008

Social network analysis explains why some sites succeed and others fail, how physical and online social networks differ and are alike, and attempts to predict how they will evolve.
Privacy and securityA multidimensional problem
Authors: Landau Susan
Published: October 2008

It's not just science or engineering that will be needed to address security concerns, but law, economics, anthropology, and more.
Legally speaking
Quanta
fying the value of patent exhaustion
Authors: Samuelson Pamela
Published: October 2008

Should patents confer power to restrict reuses and redistributions of products embodying the whole or essential parts of inventions?
CTO Roundtable
Authors: Creeger Mache
Published: October 2008

Virtualization technology is hot again, but for the right reasons?
Jim Gray, astronomer
Authors: Szalay Alexander S.
Published: October 2008

How he helped develop the SkyServer, delivering computation directly to terabytes of astronomical data.
PuzzledCircular food
Authors: Winkler Peter
Published: October 2008

Welcome to three new challenging mathematical puzzles. Solutions to the first two will be published next month; the third is as yet unsolved, so you may need extra luck with that one. Here, I concentrate on circular food, so you might want to eat something before jumping in.