bluuebunny/crossref_metadata_2025 huggingface dataset:
Pleasant Bayou Geopressured-Geothermal Reservoir Analysis—October 1991
Authors: Riney T. D.
Published: April 2008

Many sedimentary basins contain formations with pore fluids at pressures higher than hydrostatic value; these formations are called geopressured. The pore pressure is generally well in excess of hydrostatic and the fluids are saline, hot, and contain dissolved methane. The U.S. Department of Energy (DOE) has drilled and tested deep wells in the Texas-Louisiana Gulf Coast region to evaluate the geopressured-geothermal resource. Geological information for the Pleasant Bayou geopressured resource in southeast Texas is most extensive among the reservoirs tested. Testing of the DOE well (Pleasant Bayou No. 2) was conducted during 1979–1983; testing resumed in May 1988. A numerical simulator is employed to synthesize and integrate the geological information, formation rock and fluid properties data from laboratory tests, and well data from the earlier (1979–1983) and the ongoing testing (1988–1991) of the well. A reservoir simulation model has been constructed which provides a detailed match to the well test history to date.
Analysis and Optimization of Thermal Stratification and
Self-Pressurization Effects in Liquid Hydrogen Storage Systems—Part 1: Model
Development
Authors: Gursu S. , Sherif S. A. , Veziroglu T. N. , Sheffield J. W.
Published: April 2008

This paper reports on analyses and optimization studies of problems associated with liquid hydrogen thermal stratification and self-pressurization in cryogenic vessels. Three different pressure rise models were employed to calculate the self-pressurization and boil-off rates. These are a homogeneous model, a surface-evaporation model, and a thermal stratification model. The first two models are based on the assumption that no temperature gradients exist in the tank, while the thermal stratification model takes the temperature distribution into account. Employing the thermal stratification model, temperature gradients and their effect on the pressure rise rates in liquid hydrogen tanks are analyzed.
Formation Permeability Determination by Micro or Mini-Hydraulic Fracturing
Authors: Abousleiman Y. , Cheng A. H.-D. , Gu H.
Published: April 2008

This paper presents a theory and its application for post-fracture pressure-transient analyses. The proposed procedure, known as “impulse fracture test,” is an injection/falloff test designed for the determination of formation permeability and reservoir pressure. The hydraulically induced fracture can pass the near wellbore damaged zone and expose a larger formation area to flow. The permeability and reservoir pressure determined are therefore more representative of the reservoir. The theory is based on the distribution of sources with variable intensity along the fracture trajectory. For field applications, asymptotic solutions are derived to give the “type-curve” capability for the estimation of formation permeability and reservoir pressure. Assorted slope behaviors, such as −1, −2, +1/2 and +1 slopes, are predicted from various pressure and pressure derivative plots. Analyses of data from two wells which were inadvertently fractured support these behaviors.
Environmental and Energy Efficiency Evaluation of Residential Gas and Heat Pump Heating
Authors: Ganji A. R.
Published: April 2008

Energy efficiency and source air pollutant emission factors of gas heaters, gas engine heat pumps, and electric heat pumps for domestic heating have been evaluated and compared. The analysis shows that with the present state of technology, gas engine heat pumps have the highest energy efficiency followed by electric heat pumps and then gas heaters. Electric heat pumps produce more than twice as much NOx, and comparable CO2 and CO per unit of useful heating energy compared to natural gas heaters. CO production per unit of useful heating energy from gas engine heat pumps without any emission control is substantially higher than electric heat pumps and natural gas heaters. NOx production per unit of useful heating energy from natural gas engine heat pumps (using lean burn technology) without any emission control is about the same as effective NOx production from electric heat pumps. Gas engine heat pumps produce about one-half CO2 compared to electric heat pumps.
Selection of Slim Hole Core Rods by Vibratory Analysis
Authors: Eustes A. W. , Mitchell B. J. , Stoner M. S.
Published: April 2008

This paper describes the axial, torsional, and transient buckling vibratory models developed for the selection of optimum core rod size. The axial and torsional vibratory core rod simulator (VCRS) models are coupled by way of a transient buckling wave which propagates over the length of the core rod. This paper reports the frequencies and magnitudes of the stresses in the 101 core rod now in use. In addition, four core bit vibratory forcing functions for thrust and torque were developed. The thrust and torque frequencies and magnitudes for the bit forcing functions were extracted from full-size laboratory core bit tests with fast Fourier transforms. The natural frequencies of the core rod were determined with closed-form solution models and were confirmed with a finite element model. Finally, a selection of core rod sizes were modeled to determine the best size to minimize damaging stress which stems from vibration.
A Two-Temperature Model of the Regenerative Solid-Vapor Heat Pump
Authors: Fuller T. A. , Wepfer W. J. , Shelton S. V. , Ellis M. W.
Published: April 2008

A thermally driven heat pump using a solid/vapor adsorption/desorption compression process is thermodynamically analyzed. Heat regeneration between the two adsorbent beds is accomplished through the use of a circulating heat transfer (HX) fluid. Effective heat regeneration and system performance requires that steep thermal profiles or waves be established in the beds along the path of the HX-fluid flow direction. Previous studies by Shelton, Wepfer, and Miles have used square and ramp profiles to approximate the temperature profiles in the adsorbent beds, which, in turn, enable the thermodynamic performance of the heat pump to be computed. In this study, an integrated heat transfer and thermodynamic model is described. The beds are modeled using a two-temperature approach. A partial differential equation for the lumped adsorbent bed and tube is developed to represent the bed temperature as a function of time and space (along the flow direction), while a second partial differential equation is developed for the heat transfer fluid to represent the fluid temperature as a function of time and space (along the flow direction). The resulting differential equations are nonlinear due to pressure and temperature-dependent coefficients. Energy and mass balances are made at each time step to compute the bed pressure, mass, adsorption level, and energy changes that occur during the adsorption and desorption process. Using these results, the thermodynamic performance of the heat pump is calculated. Results showing the heat pump’s performance and capacity as a function of the four major dimensionless groups, DR, Pe, Bi, and KAr, are presented.
Improved field emission characteristics of individual carbon nanotube coated with boron nitride nanofilm
Authors: Morihisa Yuji , Kimura Chiharu , Yukawa Makoto , Aoki Hidemitsu , Kobayashi Takumi , Hayashi Shigeki , Akita Seiji , Nakayama Yoshikazu , Sugino Takashi
Published: April 2008

An individual multiwall carbon nanotube (CNT) synthesized without a catalyst by an arc discharge method is bonded to a tungsten tip. Field emission characteristics of the individual CNT coated with a boron nitride (BN) nanofilm are investigated. The BN film is synthesized by plasma-assisted chemical vapor deposition method in which boron trichloride (BCl3) and nitrogen (N2) are used as source gases. Deposition of the BN film with a thickness less than 10nm onto the individual CNT is attempted. Field emission characteristics are measured in the chamber evacuated to 2×10−8Pa. An anode electrode is set 25mm away from the CNT sample. The turn-on electric field, designated as an electric field at an emission current of 1.0nA, is compared between individual CNTs with and without the BN nanofilm. A significant reduction in the turn-on electric field is achieved by coating with the BN nanofilm. The turn-on electric field is estimated to be 1.2×10−2V∕μm for the uncoated individual CNT sample, and the turn-on electric field is estimated to be 8.2×10−3V∕μm for the CNT sample coated with BN nanofilm. Moreover, stable operation is demonstrated at an emission current as high as 1×10−5A.
Field emission properties of metallic nanostructures self-assembled on nanoporous alumina and silicon templates
Authors: Cahay M. , Garre K. , Fraser J. W. , Lockwood D. J. , Semet V. , Thien Binh Vu , Kanchibotla B. , Bandyopadhyay S. , Grazulis L. , Das B.
Published: April 2008

Two types of nanoscale field emitter arrays have been self-assembled using either flexible alumina templates containing hexagonal close packed pores that are 50nm wide and 500nm long or nanoporous Si templates. The first type is an array of gold “nanopinetrees” obtained by e-beam evaporation of a few nanometers of gold on bare alumina templates. The second type is a nickel “nanoblade” array formed by e-beam evaporation of a few nanometers of nickel on nanoporous Si templates. The field emission characteristics of both mesoscopic structures were measured using a scanning field emission microscope, and results were analyzed in terms of the cathode material emission. This synthetic approach for producing nanoscale field emitters could lead to a versatile and inexpensive technology for synthesizing flexible arrays of nanoscale cold cathode emitters.
Fabrication and operation of triode electron emitters as ion source for miniature mass spectrometer
Authors: Cho Jung Bin , Lee Soonil , Yoon Hyeun Joong , Yang Sang Sik , Koh Ken Ha
Published: April 2008

We report the fabrication and operation of an ion source that can be incorporated into a micro-time-of-flight mass spectrometer. The ion source consists of an array of triode emitters with carbon-nanoparticle cathodes. We were able to extract an anode current as large as 94.3μA at a gate-bias voltage of 85V with a concomitant gate current of 38nA by using the triode structure having a recessed cathode with no gate overhang. Ion-generation tests with acetone molecules were carried out successfully, and we measured monotonic increases in the ion current and ratio between ion and electron currents with respect to acetone pressure. We also present simulation results that show equipotential and electric-field lines under different electrode-bias configurations.
SiC via fabrication for wide-band-gap high electron mobility transistor/microwave monolithic integrated circuit devices
Authors: Voss L. F. , Ip K. , Pearton S. J. , Shul R. J. , Overberg M. E. , Baca A. G. , Sanchez C. , Stevens J. , Martinez M. , Armendariz M. G. , Wouters G. A.
Published: April 2008

A process for achieving high yield of SiC through wafer via holes without trenching or micromasking and with excellent electrical connection after subsequent metal plating across full wafers was developed for use in high electron mobility transistors (HEMTs) and microwave monolithic integrated circuits (MMICs) using an inductively coupled plasma etch. Consideration was given to the choice of wafer platen, hard mask, gas chemistry, surface treatments, and plasma parameters in order to achieve an acceptable etch rate while at the same time minimizing trenching and micromasking that can harm via yield. In addition, the issue of wafer thickness variation and etch nonuniformity leading to punch through of Au pads at the bottom of the vias was addressed by the addition of a metal layer to the front side of the wafer. The etch rate achieved for 25% of a 2 in. diameter wafer is approximately 3800 Å/min while demonstrating acceptable levels of trenching and micromasking with little or no Au punch through. The final process has been demonstrated to achieve >95% yield across a full 2 in. diameter, 100 μm thick wafer with a high density of vias.
Fabrication of field-emission cathode ray tube with a unique nanostructure carbon electron emitter
Authors: Wang H. X. , Jiang N. , Hiraki H. , Harada Y. , Zhang H. , Wang J. , Haba M. , Hiraki A.
Published: April 2008

A field-emission cathode ray tube (FE-CRT) has been fabricated using a unique nanostructure carbon electron emitter called carbon nanometer electron exit (CNX) which has been developed on stainless rod substrate with a special plasma chemical vapor deposition technique. Field emission from CNX has been investigated in a vacuum of 3×10−6Torr by using a diode configuration with a 5mm diameter anode and an A-K gap of 1mm, which shows that a emission current density of 1mA∕cm2 can be obtained at an electrical field of 0.95V∕μm. When the electrical field was increased to 2.4V∕μm, an emission current density of 1.568A∕cm2 was observed. Scanning electron microscopy images and micro-Raman spectrum were used to characterize the CNX film. The design of the emission system of electronic gun was optimized by simulating the equal-potential lines using a commercial software. Finally, a 4.5in. FE-CRT with a specially designed emission system has been fabricated.
In situ field emission characterization of multiwalled carbon nanotubes
Authors: Smith R. C. , Cox D. C. , Silva S. R. P.
Published: April 2008

The field emission (FE) properties of carbon nanotubes (CNTs) are measured using nanomanipulators fitted within a scanning electron microscope. We initially investigate a group of randomly arranged CNT at the apex of a carbon fiber. Second, we use a CNT polymer composite as a substrate and physically crack it to expose CNTs. We have developed a means of selectively picking up, moving, welding, and even “burning off” unwanted CNTs to leave a fully isolated CNT for FE testing. Using the nanomanipulators, we are able to achieve anode to CNT distances down to 1μm at a minimum step size of 40nm. We show that the location of the anode plays an important role in understanding the emission process of CNTs, which ties in with previously reported work. Finally, we create a bespoke gate electrode by focussed ion beam milling of a tungsten probe and use this in investigating three terminal FE measurements of a single CNT.
Extension of lifetime of silicon field emitter arrays in oxygen ambient by carbon negative ion implantation
Authors: Oowada A. , Takeuchi M. , Sakai Y. , Gotoh Y. , Nagao M. , Tsuji H. , Ishikawa J. , Sakai S. , Kimoto T.
Published: April 2008

Extension of lifetime of silicon field emitter arrays (Si-FEAs) in oxygen ambient was achieved by implanting carbon negative ions into the emitter surface. The authors examined three samples, each of which has 1024 field emission tips and implanted with 5keV carbon negative ions to the doses of 1×1016, 3×1016, and 1×1017ionscm−2. The lifetime, the time when the emission current becomes half the maximum value after starting operation, was extended in accordance with the implantation dose. The lifetime of the sample which was dosed with 1×1017ionscm−2 was 50h, which was about 17 times as long as that of as-fabricated Si-FEA.
Field emission from lanthanum monosulfide thin films grown on the (100) magnesium oxide substrates
Authors: Fairchild S. , Cahay M. , Grazulis L. , Garre K. , Wu X. , Lockwood D. J. , Semet V. , Binh Vu Thien
Published: April 2008

Lanthanum monosulfide (LaS) films were grown by pulsed laser deposition on the (100) magnesium oxide (MgO) substrates at an elevated substrate temperature and in a background gas of H2S. The thin films have been characterized by x-ray diffraction (XRD), atomic force microscopy (AFM), and high resolution transmission electron microscopy. The film surface is composed of grainlike features with an average size of approximately 34nm. The root-mean-square variation of the film surface roughness measured over a 2×2μm2 area by AFM was found to be approximately 1.5nm. XRD data indicate that the average size of the nanocrystalline grains in the film is about 26nm, which is about twice the size of the grains found in LaS thin films deposited at room temperature on Si. The field emission (FE) properties of the films have been characterized by scanning anode field emission microscopy and are interpreted in terms of a recently developed patchwork FE model. The FE data indicate that there is roughly a seven times increase in emission area due to the (100) patch areas outcropping the surface for LaS∕MgO compared to LaS∕Si thin films.
Improvement on cold carbon field-electron emitter for commercial x-ray tube
Authors: Lv Q. N. , Wang D. A. , Li T. X. , Ju Z. M. , Liu G. Y. , Xia S. H. , Ding Y. G. , Li H. Y.
Published: April 2008

A high-temperature-resistant smooth carbon field-electron emitter (SCFE) was proposed for replacing an original high-temperature-resistant carbon field-electron emitter. We compared their electron emission, processes, post-treatment technologies, and life. A comparison shows that the new SCFE has qualities. The SCFE showed a smoother surface, with bulk tightness, improved electron emission properties, decreased emitter thickness, and the contact between electrodes is better than ever. The electron emission area has been concentrated on a thinner edge, and we obtained high precision for the tube’s electrode construction. Initial experiments indicated that those x-ray tubes with the SCFE maintained their properties from August 2006 up to the present.
The effect of added salts on the optical properties of water for high index immersion lithography fluids
Authors: Taylor J. Christopher , Costner Elizabeth A. , Goh Sumarlin , Wojtczak William , Dewulf Dean , Willson C. Grant
Published: April 2008

In immersion lithography, a high index fluid is used to enable increases in the numerical aperture (NA) of the imaging system and decrease the minimum printable feature size. Water has been used in first generation immersion lithography at 193nm to reach the 45nm node. To reach the 38 and 32nm nodes, fluids with a higher index than water are needed. Ionic additives have a higher index than water and can be added to water in high concentration to obtain a high index fluid. Generally, addition of a high index additive leads to a higher absorbance. The next generation immersion fluid should have both a high index and low absorbance. Therefore, both the index and absorbance of a series of ionic additives in water were characterized to identify an additive with a high index and low absorbance at 193nm. This study revealed that the anion dictates the optical properties of the additive. Of the anions studied, the methylsulfonate anion has the desired characteristics and was dissolved in water at high concentration using heavy metal cations. A saturated solution of lanthanum methylsulfonate had the highest index and lowest absorbance identified, n193=1.58 and α193=0.3cm−1. These high index methylsulfonate solutions were used to image line and space patterns at various NAs. Images of 32nm half-pitch were generated at 1.5 NA with the lanthanum solution. The methylsulfonate anion can be paired with microelectronics friendly quaternary ammonium cations to develop an immersion fluid with the target properties.
Field emission properties of single-walled carbon nanotube with amphoteric doping by encapsulation of TTF and TCNQ
Authors: Lee Jungwoo , Lee Wonjoo , Sim Kijo , Han Sung-hwan , Yi Whikun
Published: April 2008

Field emission (FE) currents were measured for prinstine single-walled carbon nanotubes (SWCNTs), and after encapsulation of electron withdrawing and donating molecule, i.e., 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) and tetrathiafulvalene (TTF). X-ray photoelectron spectrometer, infrared, and Raman spectrometer were used to confirm encapsulation. TCNQ-doped SWCNTs (TCNQ-SWCNT) enhanced, and TTF-doped SWCNTs (TTF-SWCNT) decreased FE properties compared with pristine SWCNTs. The turn-on field of the pristine SWCNTs, TCNQ-SWCNT, and TTF-SWCNT were calculated to be 2.5, 2.3, and 3.2V∕μm, respectively, and the maximum currents were obtained, in turn, 180, 329, and 21μA∕cm2 at the electric field of 3.6V∕μm. To explain the FE properties, the work function of doped SWCNTs were calculated from Fowler-Nordheim equation, and also the resistivity of three samples was measured by four-point probe method and compared with each other.
Effect of electrical aging on field emission from carbon nanotube field emitter arrays
Authors: Ryu Je Hwang , Kim Ki Seo , Lee Chang Seok , Jang Jin , Park Kyu Chang
Published: April 2008

We studied the effect of bias aging on the field emission properties of selectively patterned carbon nanotube field emitter arrays (CNT) grown using the resist-assisted patterning process. After electrical aging using an electric field of 6.87V∕μm for 40h, it was observed that the electron emission properties and uniformity were remarkably improved. X-ray photoelectron spectroscopy spectra show a shift of 0.2eV in the O1s peak and the concentration of oxygen is reduced. Also, transmission electron microscopy measurements showed that Ni catalyst was removed from CNT tips after aging. Therefore, after electrical aging, we obtained enhanced and stable electron emission over a wide current range.
Field emission from as grown and nitrogen incorporated tetrahedral amorphous carbon/silicon heterojunctions grown using a pulsed filtered cathodic vacuum arc technique
Authors: Panwar O. S. , Rupesinghe Nalin , Amaratunga G. A. J.
Published: April 2008

This article reports the field emission measurements on as grown tetrahedral amorphous carbon (ta-C) and nitrogen incorporated tetrahedral amorphous carbon (ta-C: N) films grown using a pulsed filtered cathodic vacuum arc technique. The effect of varying thickness on field emission in the as grown ta-C films and the effect of varying nitrogen content in ta-C: N films have also been studied. The values of threshold field of emission (Eturnon) increase with decrease of thickness in the as grown ta-C films. Nitrogen incorporation up to 5.2at.% in ta-C films decreases the value of Eturnon from 9.9to5.1V∕μm and thereafter it starts increasing again. To understand the mechanism of electron emission, a realistic energy band diagram of ta-C:N∕n++Si heterojunction has been proposed from the experimentally measured valence and conduction band offsets, using in situ x-ray photoelectron spectroscopy and optical spectroscopy data already published in DRM 9 (2000) 1148. The data are explained using the Fowler and Nordheim theory. The field emission results obtained reveal that there exists a barrier to emission and the main barrier is at the front surface and this is related to the conduction band offset of the ta-C:N∕n++Si heterojunction.
Relationship between field-emission characteristics and defects measured by Raman scattering in carbon-nanotube cathodes treated by plasma and laser
Authors: Kim W. S. , Oki H. , Kinoshita A. , Murakami K. , Abo S. , Wakaya F. , Takai M.
Published: April 2008

The relationship between field-emission characteristics and defects measured by Raman scattering for printed carbon-nanotube cathodes treated by plasma and laser was investigated. The Raman intensity ratio of the D to G bands (ID/IG) was 0.71 in the case of an untreated sample. With laser irradiation, the ID/IG ratio increased to 0.76, which resulted in the increase of the emission-current density. Moreover, with the plasma and additional laser treatment, the ID/IG ratio further increased to 1.15, which resulted in the much higher increase of the emission current density. This result indicates that the induced defects, acting as emission sites, together with the improved field-enhancement factor by the surface treatment, play important roles for increasing the field-emission current density.
Assessment of the performance of scanning capacitance microscopy for n-type gallium nitride
Authors: Sumner J. , Oliver R. A. , Kappers M. J. , Humphreys C. J.
Published: April 2008

Six GaN-based test structures were grown on sapphire to assess the effectiveness of scanning capacitance microscopy (SCM) in measuring n-type carrier concentrations in GaN. These structures were designed to test the carrier concentration and spatial detection limits of the technique using data obtained from secondary ion mass spectroscopy for comparison. It has been found that, where nonintentionally doped (nid) spacers are present between doped layers, SCM reliably and repeatably distinguished between different carrier concentrations for levels ⩾2×1017cm−3 and detected layers with thicknesses ⩾25nm. Where no nid spacers exist in samples, the spatial resolution improves to 10nm. However, the exact quantitative response of SCM is seen to be highly dependent on the particular probe used, necessitating the use of calibration standards for the quantification of unknown samples. As an example of the application of such a calibration standard, we attempt to quantify the carrier concentration in the conductive layer found adjacent to the GaN/sapphire interface in nid samples.
Picocalorimetric method for DNA sequencing
Authors: Esfandyarpour Hesaam , Pease R. Fabian W. , Davis Ronald W.
Published: April 2008

In this article, the authors present a new method for DNA sequencing based on direct measurement of heat incorporation in the DNA polymerization reaction. This picocalorimetry assay that the authors call thermosequencing is a label-free, direct, and simple technique that enables inexpensive DNA sequencing envisioned to reduce the cost of DNA sequencing by three to four orders of magnitude. The authors discuss some advantages and potentials of this real-time method and its effect on the DNA sequencing market.
Sidewall passivation assisted by a silicon coverplate during Cl2–H2 and HBr inductively coupled plasma etching of InP for photonic devices
Authors: Bouchoule S. , Patriarche G. , Guilet S. , Gatilova L. , Largeau L. , Chabert P.
Published: April 2008

Energy dispersive x-ray (EDX) spectroscopy coupled to transmission electron microscopy (TEM) is used to analyze the passivation layer deposited on the sidewall of InP submicron patterns etched in Cl2–H2 and HBr inductively coupled plasmas. It is shown that a thin Si-containing layer is deposited on the sidewalls of the etched patterns, resulting from the reaction of Cl2 or HBr with the Si wafer used as the sample tray. For Cl2-containing plasma, the deposition layer becomes thicker when hydrogen is added to the gas mixture, leading to highly anisotropic InP etching at an optimized H2 percentage. A similar effect is obtained in HBr plasma by increasing the ICP power. When O2 is added to the gas mixture, the deposited layer is changed from Si rich to more stoichiometric silicon oxide (SiO2) and the passivation effect is enhanced. EDX-TEM analysis has also been carried out on InP samples etched in Cl2–N2 plasma for comparison. A similar impact of the coverplate material on the sidewall profile is evidenced, the InP sidewall being moreover strongly In deficient in this case. These results give useful guidelines to define anisotropic etching processes scalable to large-diameter InP wafers.
Structural Basis of Toll-Like Receptor 3 Signaling with Double-Stranded RNA
Authors: Liu Lin , Botos Istvan , Wang Yan , Leonard Joshua N. , Shiloach Joseph , Segal David M. , Davies David R.
Published: April 2008

Toll-like receptor 3 (TLR3) recognizes double-stranded RNA (dsRNA), a molecular signature of most viruses, and triggers inflammatory responses that prevent viral spread. TLR3 ectodomains (ECDs) dimerize on oligonucleotides of at least 40 to 50 base pairs in length, the minimal length required for signal transduction. To establish the molecular basis for ligand binding and signaling, we determined the crystal structure of a complex between two mouse TLR3-ECDs and dsRNA at 3.4 angstrom resolution. Each TLR3-ECD binds dsRNA at two sites located at opposite ends of the TLR3 horseshoe, and an intermolecular contact between the two TLR3-ECD C-terminal domains coordinates and stabilizes the dimer. This juxtaposition could mediate downstream signaling by dimerizing the cytoplasmic Toll interleukin-1 receptor (TIR) domains. The overall shape of the TLR3-ECD does not change upon binding to dsRNA.
First, Kill the Economists
Authors: Weintraub E. Roy
Published: April 2008

The Dismal Science
. How Thinking Like an Economist Undermines Community.
By Stephen A. Marglin
. Harvard University Press, Cambridge, MA, 2008. 375 pp. $35, £22.95, €26.50. ISBN 9780674026544.

The author argues that his fellow economists' enthusiasm for the market is unwarranted and ignores the corrosive effects market relationships have on communities.
Toward the Dominance of Vision?
Authors: Keller Andreas
Published: April 2008

Sensing the Past
. Seeing, Hearing, Smelling, Tasting, and Touching in History.
By Mark M. Smith
. University of California Press, Berkeley, 2008. 190 pp. $55. ISBN 9780520254954. Paper, $19.95. ISBN 9780520254961.

This short historical survey demonstrates how sensory perception is a cultural as well as physiological act.
Outbreak of OXY-2-ProducingKlebsiella oxytocain a Renal Transplant Unit
Authors: Zárate Mariela Soledad , Gales Ana C. , Picão Renata C. , Pujol Gervasio Soler , Lanza Alejandra , Smayevsky Jorgelina
Published: April 2008

We describe aKlebsiella oxytocainfection outbreak in a renal transplant unit that involved seven patients. All strains belonged to a single pulsed-field gel electrophoresis pattern and were resistant to amoxicillin-clavulanate, cefuroxime, piperacillin-tazobactam, and aztreonam but susceptible to ceftriaxone, ceftazidime, cefepime, and imipenem. Chromosomal β-lactamase hyperproduction was caused by a point mutation in theblaOXY-2gene promoter region.
Rapid Differentiation of Methicillin-Susceptible
Staphylococcus aureus
from Methicillin-Resistant
S. aureus
and MIC Determinations by Isothermal Microcalorimetry
Authors: von Ah Ueli , Wirz Dieter , Daniels A. U.
Published: April 2008

In this study, the use of isothermal microcalorimetry (IMC) for differentiation between methicillin-resistant
Staphylococcus aureus
(MRSA) and methicillin-susceptible
S. aureus
(MSSA) and MIC determination was evaluated. It was possible to differentiate between MRSA and MSSA within 4 h, whereas the standard method required 24 h. The MICs of cefoxitin were successfully determined for MRSA and MSSA by using IMC.
Comparison of DNA Pyrosequencing with Alternative Methods for Identification of Mycobacteria
Authors: Heller Loree C. , Jones Michael , Widen Ray H.
Published: April 2008

Identification of mycobacterial clinical isolates by pyrosequencing within the hypervariable A region of the 16S rRNA gene was compared to other identification methods. For >90% of isolates, these identifications correlated to the level of complex or species. For identification of many mycobacteria, pyrosequencing offers an inexpensive alternative to traditional sequencing.
Accuracy and Potential Usefulness of Triplex Real-Time PCR for Improving Antibiotic Treatment of Patients with Blood Cultures Showing Clustered Gram-Positive Cocci on Direct Smears
Authors: Ruimy Raymond , Dos-Santos Marie , Raskine Laurent , Bert Frédéric , Masson René , Elbaz Sandrine , Bonnal Christine , Lucet Jean-Christophe , Lefort Agnès , Fantin Bruno , Wolff Michel , Hornstein Michele , Andremont Antoine
Published: April 2008

Bacterial identification and antibiotic susceptibility testing currently require 48 h when a first blood culture (BC) is positive for clustered gram-positive cocci on direct smear examination (DSE). Meanwhile, antibiotic treatment is often inadequate, reducing the chances of effective treatment or creating unnecessary selective pressure. A new real-time PCR (RT-PCR) technique that differentiates
Staphylococcus aureus
from coagulase-negative staphylococci (CoNS) and detects methicillin resistance in 90 min in BC bottles could help solve these problems. BC bottles from 410 patients with gram-positive cocci on DSE were processed by current methods, and patients' treatments were prospectively recorded. The RT-PCR assay was performed on aliquots of these BCs, which had been kept frozen. For the 121 patients who had true bacteremia, we established whether the faster availability of RT-PCR results could have led to the initiation of treatments different from those actually given. RT-PCR sensitivity and specificity were 100% for differentiating between
S. aureus
and CoNS and detecting methicillin resistance with two manufacturers' BC bottles. For 31/86 (36%) of the
S. aureus
-infected patients and for 8/35 (23%) of the CoNS-infected patients who either had suboptimal or nonoptimal treatment or were untreated 48 h after positivity was detected, the early availability of RT-PCR results could have allowed more effective treatment. Unnecessary glycopeptide treatments could have been avoided for 28 additional patients. The use of RT-PCR would increase treatment effectiveness in patients with staphylococcal bacteremia and reduce the selective pressure created by glycopeptides.
Basolateral Entry and Release of New and Old World Arenaviruses from Human Airway Epithelia
Authors: Dylla Douglas E. , Michele Daniel E. , Campbell Kevin P. , McCray Paul B.
Published: April 2008

Transmission of arenaviruses from rodent hosts to humans is generally thought to occur through inhalation or ingestion of dust or droplets containing viral particles. Here we demonstrate that two identified arenavirus receptors, α-dystroglycan (α-DG) and transferrin receptor 1 (TfR1), are expressed in polarized human airway epithelia. Lymphocytic choriomeningitis virus strains with high or low α-DG affinity and Junin virus, which binds TfR1, efficiently infected polarized epithelia only when applied to the basolateral surface or when injury compromised tight junction integrity. Viral egress from infected epithelia exhibited basolateral polarity. This study demonstrates that respiratory entry of arenaviruses occurs via basolateral receptors.
Comparative Efficacy of Neutralizing Antibodies Elicited by Recombinant Hemagglutinin Proteins from Avian H5N1 Influenza Virus
Authors: Wei Chih-Jen , Xu Ling , Kong Wing-Pui , Shi Wei , Canis Kevin , Stevens James , Yang Zhi-Yong , Dell Anne , Haslam Stuart M. , Wilson Ian A. , Nabel Gary J.
Published: April 2008

Although the human transmission of avian H5N1 virus remains low, the prevalence of this highly pathogenic infection in avian species underscores the need for a preventive vaccine that can be made without eggs. Here, we systematically analyze various forms of recombinant hemagglutinin (HA) protein for their potential efficacy as vaccines. Monomeric, trimeric, and oligomeric H5N1 HA proteins were expressed and purified from either insect or mammalian cells. The immunogenicity of different recombinant HA proteins was evaluated by measuring the neutralizing antibody response. Neutralizing antibodies to H5N1 HA were readily generated in mice immunized with the recombinant HA proteins, but they varied in potency depending on their multimeric nature and cell source. Among the HA proteins, a high-molecular-weight oligomer elicited the strongest antibody response, followed by the trimer; the monomer showed minimal efficacy. The coexpression of another viral surface protein, neuraminidase, did not affect the immunogenicity of the HA oligomer, as expected from the immunogenicity of trimers produced from insect cells. As anticipated, HA expressed in mammalian cells without NA retained the terminal sialic acid residues and failed to bind α2,3-linked sialic acid receptors. Taken together, these results suggest that recombinant HA proteins as individual or oligomeric trimers can elicit potent neutralizing antibody responses to avian H5N1 influenza viruses.
Construction and Characterization of a Human T-Cell Lymphotropic Virus Type 3 Infectious Molecular Clone
Authors: Chevalier Sébastien Alain , Ko Nga Ling , Calattini Sara , Mallet Adeline , Prévost Marie-Christine , Kehn Kylene , Brady John N. , Kashanchi Fatah , Gessain Antoine , Mahieux Renaud
Published: April 2008

We and others have uncovered the existence of human T-cell lymphotropic virus type 3 (HTLV-3). We have now generated an HTLV-3 proviral clone. We established that
gag, env, pol, pro
, and
tax/rex
as well as minus-strand mRNAs are present in cells transfected with the HTLV-3 clone. HTLV-3 p24

gag

protein is detected in the cell culture supernatant. Transfection of 293T-long terminal repeat (LTR)-green fluorescent protein (GFP) cells with the HTLV-3 clone promotes formation of syncytia, a hallmark of Env expression, together with the appearance of fluorescent cells, demonstrating that Tax is expressed. Viral particles are visible by electron microscopy. These particles are infectious, as demonstrated by infection experiments with purified virions.
Primate Lentivirus Capsid Sensitivity to TRIM5 Proteins
Authors: Kratovac Zerina , Virgen Cesar A. , Bibollet-Ruche Frederick , Hahn Beatrice H. , Bieniasz Paul D. , Hatziioannou Theodora
Published: April 2008

Mammalian cells express several factors that inhibit lentiviral infection and that have been under strong selective pressure. One of these factors, TRIM5, targets the capsid protein of incoming retrovirus particles and inhibits subsequent steps of the replication cycle. By substituting human immunodeficiency virus type 1 capsid, we were able to show that a set of divergent primate lentivirus capsids was generally not susceptible to restriction by TRIM5 proteins from higher primates. TRIM5α proteins from other primates exhibited distinct restriction specificities for primate lentivirus capsids. Finally, we identified novel primate lentiviral capsids that are targeted by TRIMCyp proteins.
Characterization of the Early Steps of Infection of Primary Blood Monocytes by Human Immunodeficiency Virus Type 1
Authors: Arfi Vanessa , Rivière Lise , Jarrosson-Wuillème Loraine , Goujon Caroline , Rigal Dominique , Darlix Jean-Luc , Cimarelli Andrea
Published: April 2008

Blood-circulating monocytes migrate in tissues in response to danger stimuli and differentiate there into two major actors of the immune system: macrophages and dendritic cells. Given their migratory behavior and their pivotal role in the orchestration of immune responses, it is not surprising that cells of the monocyte lineage are the target of several viruses, including human immunodeficiency virus type 1 (HIV-1). HIV-1 replicates in monocytoid cells to an extent that is influenced by their differentiation status and modulated by exogenous stimulations. Unstimulated monocytes display a relative resistance to HIV infection mostly exerted during the early steps of the viral life cycle. Despite intensive studies, the identity of the affected step remains controversial, although it is generally assumed to take place after viral entry. We reexamine here the early steps of viral infection of unstimulated monocytes using vesicular stomatitis virus G protein-pseudotyped HIV-1 virions. Our data indicate that a first block to the early steps of infection of monocytes with these particles occurs at the level of viral entry. After entry, reverse transcription and integration proceed with extremely slow kinetics rather than being blocked. Once completed, viral DNA molecules delay entry into the nucleus and integration for up to 5 to 6 days. The inefficacy of these steps accounts for the resistance of monocytes to HIV-1 during the early steps of infection.
Excess mortality during heat waves and cold spells in Moscow, Russia
Authors: Revich B , Shaposhnikov D
Published: April 2008

Objectives:

To estimate excess mortality during heat waves and cold spells, and to identify vulnerable population groups by age and cause of death.

Methods:

Daily mortality in Moscow, Russia from all non-accidental, cardiovascular and respiratory causes between January 2000 and February 2006 was analysed. Mortality and displaced mortality during cold spells and heat waves were estimated using independent samples t tests.

Results:

Cumulative excess non-accidental mortality during the 2001 heat wave was 33% (95% CI 20% to 46%), or approximately 1200 additional deaths, with short-term displaced mortality contributing about 10% of these. Mortality from coronary heart disease increased by 32% (95% CI 16% to 48%), cerebrovascular mortality by 51% (95% CI 29% to 73%) and respiratory mortality by 80% (95% CI 57% to 101%). In the 75+ age group, corresponding mortality increments were consistently higher except respiratory deaths. An estimated 560 extra deaths were observed during the three heat waves of 2002, when non-accidental mortality increased by 8.5%, 7.8% and 6.1%, respectively. About 40% of these deaths were brought forward by only a few days, bringing net mortality change down to 3.2% (95% CI 0.8% to 5.5%). The cumulative effects of the two cold spells in 2006 on mortality were significant only in the 75+ age group, for which average daily mortality from all non-accidental causes increased by 9.9% (95% CI 8.0% to 12%) and 8.9% (95% CI 6.7% to 11%), resulting in 370 extra deaths; there were also significant increases in coronary disease mortality and cerebrovascular mortality.

Conclusions:

This study confirms that daily mortality in Moscow increases during heat waves and cold spells. A considerable proportion of excess deaths during heat waves occur a short time earlier than they would otherwise have done. Harvesting, or short-term mortality displacement, may be less significant for longer periods of sustained heat stress.
Drought-induced metal release from a wetland at Plastic Lake, central Ontario
Authors: Adkinson Angela , Watmough Shaun A , Dillon Peter J
Published: April 2008

With climate change, droughts may become more frequent in southern Ontario, which could release metals from peat and degrade downstream water quality. Monthly volume-weighted metal (Al, Ba, Be, Cd, Co, Mn, Ni, Pb, Sr, and Zn) concentrations and fluxes in streams and bulk deposition at Plastic Lake were monitored over 20 months in 2002–2003, during which there was a summer drought. Monthly concentrations in the outflow from the wetland (PC1) were variable, with very high concentrations following the drought. With the exception of Pb, statistically significant models of metal concentrations with SO42– and dissolved organic carbon concentrations were developed, and these relationships were used to estimate monthly metal exports between 1980 and 2000. Model predictions for Cd and Zn in PC1 agreed well (p < 0.001) with concentrations measured between 1989 and 1991. Model predictions suggesting peaks in metal concentrations are common in years with pronounced summer droughts. In contrast to ombrotrophic bogs, the PC1 wetland receives the majority of its metal input from the terrestrial catchment, and mass balance approximations indicate no substantial depletion of metal reserves in peat. Drought-induced metal peaks may persist for many decades, potentially contributing to the delayed recovery of surface waters at Plastic Lake, despite declining S deposition.
Long-term trends in zooplankton of Dorset, Ontario, lakes: the probable interactive effects of changes in pH, total phosphorus, dissolved organic carbon, and predators
Authors: Yan Norman D , Somers Keith M , Girard Robert E , Paterson Andrew M , Keller W. (Bill) , Ramcharan Charles W , Rusak James A , Ingram Ron , Morgan George E , Gunn John M
Published: April 2008

Time trends in abundance, body size, species richness, and species composition indicate that crustacean zooplankton communities of southern Canadian Shield lakes changed between 1980 and 2003. Total abundance did not decline despite reductions in total phosphorus, but all other metrics changed. Species richness declined in Harp Lake (Ontario, Canada) following its Bythotrephes invasion, but richness increased in three other lakes. Average cladoceran body length increased from 0.6 to 1.0 mm in seven of the lakes, as larger-bodied taxa replaced smaller ones. Correlations with water quality and fish metrics suggest that cladoceran size increases were attributable to many factors: a decline in food availability following declining phosphorus levels increasing the competitive advantage of larger herbivores, a decline in acidity favouring the larger, acid-sensitive daphniids, and reduced risk of planktivory linked to a rise in dissolved organic carbon levels and changes in predation regimes. Zooplankton communities on the Canadian Shield are changing, and these changes are best viewed in a multiple-stressor context. Key anthropogenic stressors have also changed and may do so again if Ca concentrations continue to decline.
Effect of hypoxia on habitat quality of striped bass (Morone saxatilis) in Chesapeake Bay
Authors: Costantini Marco , Ludsin Stuart A , Mason Doran M , Zhang Xinsheng , Boicourt William C , Brandt Stephen B
Published: April 2008

Eutrophication-induced hypoxia may affect both benthic and pelagic organisms in coastal systems. To evaluate the effect of hypoxia on pelagic striped bass (Morone saxatilis), we quantified the growth rate potential (GRP) of age-2 and age-4 fish in Chesapeake Bay during 1996 and 2000 using observed temperature, dissolved oxygen, and prey abundance information in a spatially explicit bioenergetics modeling framework. Regions of the Bay with bottom hypoxia were generally areas with high quality habitat (i.e., GRP > 0 g·g–1·day–1), primarily because prey fish were forced into warm, oxygenated surface waters suitable for striped bass foraging and growth. In turn, by concentrating fish prey above the oxycline and removing bottom waters as a refuge, hypoxia likely enhanced striped bass predation efficiency and contributed to the recovery of striped bass during the mid-1990s, a time when the striped bass fishery also was closed. This short-term positive effect of hypoxia on striped bass, however, appears to have been counterbalanced by a long-term negative effect of hypoxia in recent years. Ultimately, hypoxia-enhanced predation efficiency, combined with an abundance of striped bass due to restricted harvest, appears to be causing overconsumption of prey fishes in Chesapeake Bay, thus helping to explain poor growth and health of striped bass in recent years.
Long-term changes in phytoplankton composition in seven Canadian Shield lakes in response to multiple anthropogenic stressors
Authors: Paterson Andrew M , Winter Jennifer G , Nicholls Kenneth H , Clark Bev J , Ramcharan Charles W , Yan Norman D , Somers Keith M
Published: April 2008

We examined long-term changes in phytoplankton composition from 1981 to 2003 in seven intensively studied lakes on the southern Canadian Shield in Ontario, Canada. Significant (P < 0.05), temporally coherent increases in the relative biovolume of colonial chrysophytes were observed in six of the seven lakes, with coincident declines in the relative biovolume of diatom algae. Variance partitioning analyses identified water chemistry variables, and the co-variation of water chemistry with physicoclimatic variables, as most important in structuring phytoplankton assemblages through time in the study lakes (variance explained: chemical variables (14%–47%, mean = 28.7%); chemistry and physicoclimatic variables (21%–30%, mean = 25.5%)). With the exception of Harp Lake, which was invaded by Bythotrephes in the early 1990s, grazing variables did not explain a significant portion of the phytoplankton variance. We hypothesize that the long-term changes in phytoplankton species composition is attributable to multiple anthropogenic stressors acting at a regional scale. Our results, coupled with paleoecological studies, indicate that increases in the relative importance of colonial chrysophytes are coincident with water chemistry changes associated with industrial activity since the mid-1900s and physical changes linked to climate indices such as the North Atlantic Oscillation.