bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Transfer From a Cylinder in Crossflow With Transpiration Cooling
Authors: Johnson B. V. , Hartnett J. P.
Published: February 2012

Local heat-transfer measurements are reported for a transpiration-cooled cylinder in crossflow. The stagnation point measurements are found to be in good agreement with results from plane stagnation flow theory. In the laminar region beyond the stagnation point, the equivalent wedge method is found to predict heat-transfer performance within 10 percent of the experimental values. In the separated flow region the experimental results demonstrate that the transpiration process is still very effective in reducing the heat transfer.
A High Pressure Differential Manometer
Authors: Barnett S. C. , Jackson T. W. , Whitsides R. H.
Published: February 2012

A unique manometer has been designed and successfully used to measure pressure drops of a few millimeters of mercury at static pressures up to 10,000 psia. The manometer, which utilizes a column of water and mercury, is a primary standard because the mercury surface is visible at all times. It is designed for static pressures up to 20,000 psi; however, very minor revisions would make the manometer suitable for pressures up to 50,000 psi. A description of the manometer and pertinent equations is included.
Heat Transfer From a Small Isothermal Spanwise Strip on an Insulated Boundary
Authors: Ling S. C.
Published: February 2012

Detailed analysis of heat transfer of an isothermal spanwise strip in a uniform shear field is presented. Solutions for the leading edge and the trailing edge are obtained by method of relaxation. These solutions are exact in that the streamwise heat conduction term, in the differential equation of energy, is not neglected. The results are compared with the Le´veˆque similarity solution, and the ranges where the solution is valid are defined. A similarity solution for the trailing wake is also presented.
Free Convective Heat Transfer to Supercritical Water Experimental Measurements
Authors: Fritsch C. A. , Grosh R. J.
Published: February 2012

Laminar free convective heat transfer from a vertical flat plate has been studied for water close to its critical point where there are marked variations in density and specific heat. All of the trends indicated in the authors’ previous analytical investigation were verified by the experimental data. There was a systematic deviation of about 20 percent—the analytical results being consistently lower than the experimental observations. However, this could easily be due to the lack of precise thermal conductivity and dynamic viscosity data for the region of interest. This investigation has established that the basic conservation and state equations with variable properties may be used to adequately describe laminar free convection heat transfer in supercritical water up to a few tenths of a degree from the critical point.
Effect of Surface Roughness on the Total Hemispherical and Specular Reflectance of Metallic Surfaces
Authors: Birkebak R. C. , Sparrow E. M. , Eckert E. R. G. , Ramsey J. W.
Published: February 2012

Measurements have been made of the hemispherical and specular reflectance of metallic surfaces of controlled roughness. The surfaces, which were ground nickel rectangles, were irradiated at various angles of incidence by a beam of black-body radiation, the temperature of which was also varied. The instrumentation which was devised to perform the experiments is described. The measurements show that beyond a certain surface roughness, the hemispherical reflectance is virtually independent of further increases in roughness. On the other hand, the specular reflectance decreases steadily with increasing roughness. Additionally, the hemispherical reflectance is found to be quite insensitive to the angle of incidence, while the specular reflectance increases with angle of incidence for the rougher surfaces.
Temperature Relations in Shell and Tube Exchangers Having One-Pass Split-Flow Shells
Authors: Jaw Luis
Published: February 2012

Mean temperature difference correction factors are presented in the usual dimensionless groups of P and R for shell and tube heat exchangers where the shell fluid is divided into two streams entering at the center of the shell. Mathematical expressions have been derived for the thermal effectiveness P for both two and four tube passes in terms of UA/wc and wc/WC designated as R. The expressions for the split-flow exchangers with one and with an infinite number of tube passes are also presented. The analysis is further extended so that the correction factor F for split-flow exchangers of four tube passes and an infinite number of tube passes may be used for any even number of tube passes within a practical design range. There is very little difference between correction factors of values above 0.8, for split-flow exchangers with two, four, and infinite number of tube passes, and the conventional 1–2 shell and tube exchanger. An interesting result is noted that for each value of R there is a peak value of P.
Flame-Contact Studies
Authors: Stoll A. M. , Chianta M. A. , Munroe L. R.
Published: February 2012

This paper is composed of three parts: 1 Apparatus and method for determination of heat transfer through fabric during flame contact; 2 experimental validation of mathematical analysis and heat flow; 3 application to determination of thermal properties of materials in thin layers.
Approximate Method for the Study of Heat Conduction in Bars of Arbitrary Cross Section
Authors: Laura Patricio A. , Chi Michael
Published: February 2012

The method to be described consists in use of conformal mapping for solving certain unsteady state temperature distribution problems.
An Analysis of Burnout Conditions for Flow of Boiling Water in Vertical Round Ducts
Authors: Becker K. M. , Persson P.
Published: February 2012

A method of predicting the burnout conditions for flow of boiling water in vertical round ducts is presented. The analysis predicts that the burnout conditions are independent of the L/d-ratio and the inlet temperature, and that the burnout steam quality decreases with increasing surface heat flux and increasing mass velocity. It was also found that the burnout steam quality at low pressures increases with the pressure and reaches a maximum at approximately 70 kg/cm2, and thereafter decreases with a further increase of the pressure. The theoretical result compares very well with experimental data from different sources.
The Influence of Wall Conductance on Magnetohydrodynamic Channel-Flow Heat Transfer
Authors: Snyder W. T.
Published: February 2012

An analysis is made of the influence of finite electrical conductivity of the walls on fully developed magnetohydrodynamic channel-flow heat transfer. The analysis is based on arbitrary external electrical loading and is thus valid for both generator and accelerator modes of operation. Constant properties of the fluid and walls are assumed. It is shown that under certain operating conditions of external electrical loading, the fluid bulk to wall temperature difference for conducting walls differs substantially from that for electrically insulating walls. Representative numerical calculations are presented.
Temperature Distributions in Circular Fins of Rectangular Profile
Authors: Newhouse Keith N.
Published: February 2012

A particular solution is given for the temperature distribution in a thin circular fin of rectangular profile with both circumferential and radial heat flow.
A Generalized Variational Method for Calculating Radiant Interchange Between Surfaces
Authors: Sparrow E. M. , Haji-Sheikh A.
Published: February 2012

A variational expression is devised from which the governing equations are derivable for all problems of radiant interchange between diffusely emitting and reflecting surfaces. This correspondence between the variational expression and the equations of radiant interchange serves as the basis of an approximate solution method for radiation heat transfer problems. The solution method is discussed in general and then applied to specific physical situations. It is shown that the variational method yields results with remarkable ease, especially when compared with the formidable computational task inherent in a direct numerical assault on the governing integral equations.
On Constant Property Turbulent Boundary Layers With Variable Temperature or Heat Flow at the Wall
Authors: Back L. H. , Seban R. A.
Published: February 2012

Recent numerical solutions of Spalding’s form of the thermal energy equation are compared to other, more limited, analytic solutions of the energy equation that have been used for situations in which the temperature at the wall or the heat flux at the wall varies with distance along the wall. For Prandtl numbers near unity the two kinds of solutions are comparable and they predict well the heat transfer for flow along a flat plate. For variable free stream velocity the discrepancies found between experiment and the older solutions remain the same with the new ones. Another model of the thermal boundary layer is presented by which better agreement with experiment is obtained for accelerated flows.
Initial Boundary Layer Effects on Laminar Flows With Wall Slot Injection
Authors: Schetz J. A. , Jannone J.
Published: February 2012

An analytical investigation of the effects of an initial splitter plate boundary layer on the flow field associated with the slot injection of a gas in laminar flow is presented. The analysis is based on the method of collocation, using profiles generated by a modified Oseen approximation to the momentum equation, and the results are presented in terms of the effects on skin friction and heat transfer coefficients. It is shown that the initial boundary layer thickness can be an important parameter in describing the flow field.
The Dip-Forming Process
Authors: Horvay G.
Published: February 2012

A cool slab of metal when dipped into the bath of a molten metal first freezes metal from the bath; then—if kept there long enough—the frozen crust and the slab melt out. The same result is obtained in a continuous process where the slab is pulled through the melt. In this paper a theory is developed for the process, assuming that the material properties of bath and slab are the same. The governing partial differential equation is established, and is approximated by four-node (“3-channel”) and two-node (“1-channel”) difference-differential equations. It is shown that when the slab is passed through the bath at a speed exceeding a value 5 of the Peclet number p, it is adequate to regard the slab in the calculations as suddenly dipped into the bath and then kept there for a time equal to the time of travel through the bath. The solutions of the 1-channel equations are presented in the form of dimensionless curves which give the mean temperature of the slab as function of position and show the growth and decrease of the slab thickness. Good agreement is obtained with available test results for dip-formed copper.
The Effect of Transverse Temperature Gradients on the Heat Transfer and Friction for Laminar Flow of Gases
Authors: Davenport M. E. , Leppert G.
Published: February 2012

The results of an experimental investigation of the frictional and heat transfer effects for gases passing through heated channels with Reynolds numbers from 200 to 2000 and with values of the ratio of the temperature of the wall to the bulk temperature of the gas up to 2.2 are presented. Local friction factors, not previously available, were found to increase much more rapidly with temperature ratio than predicted by existing analysis [1]. Local heat transfer results are compared to and found to agree with the results of Kays and Nicoll [2]. Previous analyses which include the variation of gas properties with temperature are inadequate to explain the substantial increase in friction factor with temperature ratio. The effects of a postulated radial velocity component are examined and are found to be adequate to explain the friction factor and Nusselt number results.
Unsteady Stagnation Point Heat Transfer
Authors: Chao B. T. , Jeng D. R.
Published: February 2012

An analysis is presented for the unsteady laminar, forced-convection heat transfer at a two-dimensional and axisymmetrical front stagnation due to an arbitrarily prescribed wall temperature or heat flux variation. The flow is incompressible and steady. The procedure begins with a consideration of the thermal boundary-layer response caused by either a step change in surface temperature or heat flux. Two appropriate asymptotic solutions, valid for small and large times, respectively, are found and satisfactorily joined for Prandtl numbers ranging from 0.01 to 100. The key to the small time solution is the transformation of the energy equation in the Laplace transform plane to an ordinary differential equation with a large parameter. An essential feature of the large time solution is the use of Meksyn’s transformation variable and the method of steepest descent in the evaluation of integrals. It is found that, for both two-dimensional and axisymmetrical stagnation, the time required for the thermal boundary layer to attain steady condition, for either a step change in surface temperature or heat flux, varies inversely with the free stream velocity and directly with 1/4 power of the Prandtl number of the fluid.
Measured Temperature Profiles Within the Superheated Boundary Layer Above a Horizontal Surface in Saturated Nucleate Pool Boiling of Water
Authors: Marcus B. D. , Dropkin D.
Published: February 2012

Temperature measurements were made within the superheated boundary layer above and adjacent to a horizontal heating surface in saturated, nucleate, pool boiling of water. A microthermocouple probe was used to measure the average temperature profiles and the temperature fluctuations within the boundary layer at heat fluxes from 1000 to 40,000 Btu/hr-sq ft. Correlations are presented for the “extrapolated” thickness of the boundary layer (δ) as well as the temperature distribution within it. It was found that the thickness (δ) could be expressed in terms of the heat-transfer coefficient as: δ = Chd. Also, the behavior of δ with system parameters was found to agree with that predicted by Han and Griffith [3] and Hsu [4] in their theories of nucleation from surface cavities. The temperature distribution in the boundary layer from the surface to 0.57δ was essentially linear and could be expressed: (T − Tb)/(Ts − Tb) = 1 − (y/δ). Above 0.57δ the temperature profile became an inverse power function of the height above the surface: (T − Tb)/(Ts − Tb) = D(y/δ)−a.
Mass Transfer From a Rotating Cone in Axisymmetric Flow
Authors: Salzberg F. , Kezios S. P.
Published: February 2012

The mass-transfer by sublimation from the surface of a stationary or rotating naphthalene cone oriented axisymmetrically in an airstream is experimentally investigated. The cone employed has a 30-deg total included angle and is five in. long. Air velocities ranged up to about 50 ft/sec whereas the ratio of the tangential velocity of the conical surface (at its base) to the mainstream speed ranged up to about 7.2; for the stationary cone air speeds up to about 100 ft/sec were employed. Local mass-transfer rates are determined by measuring the depth of the sublimed naphthalene. Results are correlated in dimensionless form using either the distance along the surface and the local velocity or the spiral length and resultant velocity. The flow pattern about the stationary and rotating cone is photographed using the smoke-filament technique.
Transient Heat Transfer Through a Thin Circular Pipe Due to Unsteady Flow in the Pipe
Authors: Hayasi N. , Inouye K.
Published: February 2012

An analysis of the transient heat transfer between a thin circular tube and the incompressible fluid moving through the tube is made for the case where the temperature of the inlet fluid is kept constant. Both radial conduction of heat in the wall and the heat loss at the outer surface of the cylinder are taken into consideration. It is shown to be especially easy to calculate temperature of both fluid and tube in the initial period by means of the figures. So far, it is common to use the temperature of the wall calculated by the assumption that it is constant radially. It is shown that for the insulated tube in the initial period such temperature is equal to the temperature of the outer surface of the tube. The temperature of the inner surface of the tube may be appreciably different from such temperature even for the metallic tube. The difference is extremely large for the tube made from insulating material.
Influence of Tube Orientation on Combined Free and Forced Laminar Convection Heat Transfer
Authors: Iqbal M. , Stachiewicz J. W.
Published: February 2012

Combined free and forced convection inside inclined circular tubes is studied theoretically. The case considered is that of fully developed laminar flow with constant-pressure gradient and constant-heat flux. Fluid properties are considered constant except for the variation of density in the buoyancy terms. Upward flow only is considered. Velocity and temperature fields are calculated by perturbation analysis in terms of power series of Rayleigh numbers. A detailed analysis of the final equations is made to determine the range of values of nondimensional parameter such as Rayleigh and Reynolds numbers over which the mathematical results are valid. Nusselt numbers are calculated based on bulk temperature difference and in final form are also expressed in terms of power series of Rayleigh numbers. Rayleigh number appears to be the dominant parameter in equations of velocity and temperature fields and Nusselt number. However Rayleigh and Reynolds number product and Prandtl number also influence the equations independently. As the tube inclination varies from horizontal, the Nusselt number increases up to a maximum which may occur before the vertical position is reached. The angle at which this maximum occurs appears to be a function of Rayleigh, Reynolds, and Prandtl number, and in most instances lies between 20 and 60 deg of tube inclination.
Radiative Heat Exchange Between Conducting Plates With Specular Reflection
Authors: Hering R. G.
Published: February 2012

Heat transfer by simultaneous internal conduction and surface radiation is considered for two equal-length thin plates sharing a common edge. The external surfaces of the plates are insulated while the internal surfaces are gray, specular reflectors for thermal radiation. The problem is formulated in terms of a nonlinear integrodifferential equation which is converted to an integral equation and then solved numerically. Solutions have been obtained for a wide range of conditions including those for which diffuse reflection results are available. Temperature and local heat loss distributions as well as total heat loss calculations are presented and compared with those for diffuse reflectors. Temperatures are lower while local and total heat loss are greater for specular reflection than for diffuse reflection. With applications to radiating fins of rectangular profile in mind, fin effectiveness for specularly reflecting fins are presented and compared to the results for diffuse reflection. The effectiveness of specularly reflecting fins is greater than that of diffusely reflecting fins.
Heat-Transfer Effects on the Developing Laminar Flow Inside Vertical Tubes
Authors: Lawrence W. T. , Chato J. C.
Published: February 2012

A numerical method was developed for the calculation of entrance flows in vertical tubes for the cases of upflow or downflow and constant wall heat flux or constant wall temperature. The solutions were in excellent agreement with experimental data obtained with water flowing upward in a vertical heated tube. The results show that both the density and the viscosity have to be treated as nonlinear functions of temperature. Consequently, for the constant heat flux condition, the velocity and temperature profiles constantly change and never reach “fully developed” states. The transition to turbulent flow was also studied. The experimental measurements demonstrated that the transition process depends on the developing velocity profiles. For the constant heat flux case, transition will always occur at some axial position. For a given entrance condition, the distance to transition is fixed by the fluid flow rate and the wall heat flux. For the experimental results, a tentative transition criterion was obtained, which depends only on the velocity profile shape, fluid viscosity, and the entrance Reynolds number.
Simultaneous Radiation, Conduction, and Convection in a Spectrally Selective, Emitting, and Scattering Porous Bed
Authors: Leung A. T. , Edwards D. K.
Published: February 2012

An exact formulation of simultaneous radiation, conduction, and convection heat transfer for steady-state conditions in a one-dimensional, semi-infinite, isotropic, homogeneous, absorbing, and scattering porous bed is presented. Both diffuse and collimated radiant fluxes are incident on the bed causing absorption, scattering, emission, and heating of the bed which in turn heats a transparent, constant-property fluid flowing normal to the surface. Spectral selectivity is allowed for when the source energy is of shorter wavelength than the emitted energy. Exact and approximate numerical solutions and a linearized closed-form solution are given for inflow, as in a solar heat collector, and outflow, as with a heat shield.
Analysis of Two-Phase, One-Component Stratified Flow With Condensation
Authors: Rufer C. E. , Kezios S. P.
Published: February 2012

A physical model is constructed for the stratified two-phase flow pattern with annular, laminar film condensation superimposed and the equivalent mathematical model is analyzed. Utilizing the principle of conservation of mass, energy, and momentum, an equation is derived which gives the slope of the vapor-bulk liquid interface along the tube. By varying the flow rate, inclination of the tube, tube radius, and film temperature difference, the effect of these variables on the flow level is illustrated in a typical example. A special case of this equation, namely, that describing the vapor-liquid interface when the rate of condensation is zero, is compared with several recent empirical horizontal tube holdup correlations and with flow-level data of Gazley for stratified air-water flow.
Turbulent Pipe Flow of an Internally Heat Generating Fluid
Authors: Kinney R. B. , Sparrow E. M.
Published: February 2012

Experimental measurements, supported by analysis, were performed to determine the heat-transfer characteristics of an internally heat generating fluid in the fully turbulent regime. Heat was generated uniformly within the flow by electrical dissipation, the working fluid being an aqueous solution of sodium chloride salt. Measurements were made of the fully developed wall-to-bulk temperature differences for flow in an adiabatic pipe; data were also collected in the thermal entrance region. The Reynolds numbers and the Prandtl numbers, respectively, ranged from 10,000 to 80,000 and from 3 to 4. The small wall-to-bulk temperature differences (between 1 and 2 deg F) necessitated special care and instrumentation beyond that required in conventional turbulent heat-transfer measurements. The fully developed wall-to-bulk temperature differences were in very satisfactory agreement with the analytical calculations. The consistent scatter in the data was no more than ±7 percent over the entire Reynolds number range. The analytical solutions were found to be very sensitive to the choice of the eddy diffusivity for heat. The assumption of equal diffusivities for heat and momentum led to the most satisfactory agreement between the experimental and analytical results. Additional numerical results are presented which include fluids with Prandtl numbers ranging from 1 to 100 for Reynolds numbers from 10,000 to 150,000.
Comparison Between Exact and One-Dimensional Theories for Incipient Melting in Reentry Simulation
Authors: Matula Richard A.
Published: February 2012

The exact transient temperature distribution in a spherical region subjected to an axisymmetric reentry heat flux has been evaluated. The results are presented in terms of nondimensional parameters, therefore they are valid for a wide range of materials, flight conditions, and nose radii. The angular dependence of the surface temperature is given as a function of time. It is also shown that the true radial temperature distribution can be represented by an exponential function. Finally, the solution is applied to reentry ablation onset studies that are being conducted in the free-flight range of the GM Defense Research Laboratories. The exact solution and the one-dimensional theory for the stagnation temperature rise of a model simulating reentry conditions in the free-flight range are compared. It is shown that the validity of the one-dimensional solution is dependent on the flight time, material properties, and nose radius of the model. Assuming that a temperature can be assigned which corresponds to incipient ablation, the present analysis is particularly useful in the prediction of ablation onset.
Electrical properties and stability of an epitaxial alumina film formed on Cu-9 at. % Al(111)
Authors: Yoshitake Michiko , Nagata Takahiro , Song Weijie
Published: February 2012

An ultrathin epitaxial alumina film formed in ultrahigh vacuum on a Cu-9 at. %Al(111) single crystal was characterized by in situ low energy electron diffraction and reflection high energy electron diffraction methods and by ex situ x-ray diffraction and conducting atomic force microscopy (AFM) techniques. Ex situ measurement results on the crystal structure and surface morphology were compared with the in situ results. It was confirmed that the 1.6 nm-thick epitaxial film maintained its crystal structure and atomically flat terrace surface morphology after several months of air exposure. Current–voltage (I–V) measurements on the alumina film were performed using conducting AFM. No electrical breakdown occurred even when an electric field as strong as 2.5 × 109 V/m was applied. The band gap of the alumina film and the band alignment between the film and the substrate were determined from I–V curves.
Diverse Sensitivity Thresholds in Dynamic Signaling Responses by Social Amoebae
Authors: Wang C. Joanne , Bergmann Adriel , Lin Benjamin , Kim Kyuri , Levchenko Andre
Published: February 2012

Dictyostelium
cells with increased responsiveness to chemoattractant may promote propagation of the initial signal across the cell population.
Incidence and Predictors of Nephrotoxicity Associated with Intravenous Colistin in Overweight and Obese Patients
Authors: Gauthier Timothy P. , Wolowich William R. , Reddy Arathi , Cano Ennie , Abbo Lilian , Smith Laura B.
Published: February 2012

Intravenous colistin is used to treat resistant Gram-negative infections and is associated with nephrotoxicity. In overweight and obese adults, a paucity of data exists regarding the incidence and predictors of such toxicity. A retrospective nested case-control study was performed over 35 months for patients receiving intravenous colistin for ≥72 h with a body mass index (BMI) of ≥25 kg/m
2
. The objective was to investigate the incidence and predictors of nephrotoxicity. Severity of acute kidney injury was defined by RIFLE (risk, injury, failure, loss, and end-stage kidney disease) criteria. Dosing and mortality were secondarily investigated. Forty-two patients met the inclusion criteria, and 20 (48%) developed nephrotoxicity. Patients with toxicity were in the risk (15%), injury (5%), and failure (80%) categories based on RIFLE criteria. A logistic regression model identified four predictors of colistin-associated nephrotoxicity: a BMI of ≥31.5 kg/m
2
(odds ratio [OR], 3.1; 95% confidence interval [CI], 1.15 to 8.35), diabetes (OR, 2.11; 95% CI, 0.84 to 5.29), the length of hospitalization in days prior to receipt of colistin (OR, 1.04; 95% CI, 0.99 to 1.08), and age (OR, 1.08; 95% CI, 1.00 to 1.17). Among all of the patients, dosing based on the actual body weight and excessive dosing due to the use of the actual body weight were frequent at 64% and 92%, respectively. The 30-day all-cause in-hospital mortality rate was 40% in the toxicity group and 14% in the nontoxicity group (
P
= 0.14). Patients receiving intravenous colistin should be monitored for nephrotoxicity, especially when the BMI exceeds 31.5 kg/m
2
. Prospective, randomized, controlled trials are warranted to further examine nephrotoxicity incidence and predictors and appropriate dosing strategies in this population.
No Effect of a Single Supratherapeutic Dose of Lersivirine, a Next-Generation Nonnucleoside Reverse Transcriptase Inhibitor, on Corrected QT Interval in Healthy Subjects
Authors: Vourvahis Manoli , Wang Rong , Ndongo Marie-Noella , O'Gorman Melissa , Tawadrous Margaret
Published: February 2012

The objective of this study was to investigate the effect of a supratherapeutic dose of lersivirine (LRV) on corrected QT (QTc) interval using Fridericia's equation (QTcF) in healthy subjects. In this randomized, single-dose, placebo- and active-controlled 3-way crossover study, healthy adult males (
n
= 48) were randomized to receive LRV (2,400 mg), moxifloxacin (400 mg), or placebo for each treatment period. Triplicate 12-lead electrocardiogram measurements were performed, PK samples were collected, and vital signs were measured. Adverse event monitoring and safety laboratory testing were performed. All subjects were white (mean age, 39 years; body mass index [BMI], 25.6 kg/m
2
) and completed the study. Following LRV administration, the upper bound of the 90% confidence interval (CI) for time-matched adjusted mean differences to placebo QTcF at each time point postdose was below the regulatory threshold of 10 ms, satisfying the criteria for a negative thorough QT/QTc study. The highest upper bound of QTcF 90% CI occurred at 6 h for LRV (3.32 ms; 90% CI, 1.47 to 5.17 ms). The study was deemed adequately sensitive as the lower bound of the 90% CI for the adjusted mean QTcF differences between moxifloxacin and placebo at the moxifloxacin historical
T
max
of 3 h was >5 ms (15.29 ms; 90% CI, 13.44 to 17.14 ms). There was no statistically significant relationship between LRV exposure and placebo-adjusted change from baseline QTcF or clinically significant changes in QRS complex, pulse rate (PR) interval, heart rate, or blood pressure. LRV (2,400 mg) did not prolong the QTcF interval, and no clinically relevant electrocardiogram or vital sign changes were observed in healthy subjects.
Detection of Two Zoonotic Babesia microti Lineages, the Hobetsu and U.S. Lineages, in Two Sympatric Tick Species, Ixodes ovatus and Ixodes persulcatus, Respectively, in Japan
Authors: Zamoto-Niikura Aya , Tsuji Masayoshi , Qiang Wei , Nakao Minoru , Hirata Haruyuki , Ishihara Chiaki
Published: March 2012

The species
Babesia microti
, commonly found in rodents, demonstrates a high degree of genetic diversity. Three lineages, U.S., Kobe, and Hobetsu, are known to have zoonotic potential, but their tick vector(s) in Japan remains to be elucidated. We conducted a field investigation at Nemuro on Hokkaido Island and at Sumoto on Awaji Island, where up to two of the three lineages occur with similar frequencies in reservoirs. By flagging vegetation at these spots and surrounding areas, 4,010 ticks, comprising six species, were collected. A nested PCR that detects the 18S rRNA gene of
Babesia
species revealed that
Ixodes ovatus
and
I. persulcatus
alone were positive. Lineage-specific PCR for rRNA-positive samples demonstrated that
I. ovatus
and
I. persulcatus
carried, respectively, the Hobetsu and U.S. parasites. No Kobe-specific DNA was detected. Infected
I. ovatus
ticks were found at multiple sites, including Nemuro and Sumoto, with minimum infection rates (MIR) of ∼12.3%. However, all
I. persulcatus
ticks collected within the same regions, a total of 535, were negative for the Hobetsu lineage, indicating that
I. ovatus
, but not
I. persulcatus
, was the vector for the lineage. At Nemuro, U.S. lineage was detected in 2 of 139 adult
I. persulcatus
ticks (MIR, 1.4%), for the first time, while 48 of
I. ovatus
ticks were negative for that lineage. Laboratory experiments confirmed the transmission of Hobetsu and U.S. parasites to hamsters via
I. ovatus
and
I. persulcatus
, respectively. Differences in vector capacity shown by MIRs at Nemuro, where the two species were equally likely to acquire either lineage of parasite, may explain the difference in distribution of Hobetsu throughout Japan and U.S. taxa in Nemuro. These findings are of importance in the assessment of the regional risk for babesiosis in humans.
Irrigation Differentially Impacts Populations of Indigenous Antibiotic-Producing Pseudomonas spp. in the Rhizosphere of Wheat
Authors: Mavrodi Olga V. , Mavrodi Dmitri V. , Parejko James A. , Thomashow Linda S. , Weller David M.
Published: March 2012

This work determined the impact of irrigation on the seasonal dynamics of populations of
Pseudomonas
spp. producing the antibiotics phenazine-1-carboxylic acid (Phz
+
) and 2,4-diacetylphloroglucinol (Phl
+
) in the rhizosphere of wheat grown in the low-precipitation zone (150 to 300 mm annually) of the Columbia Plateau of the Inland Pacific Northwest. Population sizes and plant colonization frequencies of Phz
+
and Phl
+
Pseudomonas
spp. were determined in winter and spring wheat collected during the growing seasons from 2008 to 2009 from selected commercial dryland and irrigated fields in central Washington State. Only Phz
+
bacteria were detected on dryland winter wheat, with populations ranging from 4.8 to 6.3 log CFU g
−1
of root and rhizosphere colonization frequencies of 67 to 100%. The ranges of population densities of Phl
+
and Phz
+
Pseudomonas
spp. recovered from wheat grown under irrigation were similar, but 58 to 100% of root systems were colonized by Phl
+
bacteria whereas only 8 to 50% of plants harbored Phz
+
bacteria. In addition, Phz
+
Pseudomonas
spp. were abundant in the rhizosphere of native plant species growing in nonirrigated areas adjacent to the sampled dryland wheat fields. This is the first report that documents the impact of irrigation on indigenous populations of two closely related groups of antibiotic-producing pseudomonads that coinhabit the rhizosphere of an economically important cereal crop. These results demonstrate how crop management practices can influence indigenous populations of antibiotic-producing pseudomonads with the capacity to suppress soilborne diseases of wheat.
Timing of Toll-Like Receptor 9 Agonist Administration in Pneumococcal Vaccination Impacts Both Humoral and Cellular Immune Responses as Well as Nasopharyngeal Colonization in Mice
Authors: Jensen Katrine M. , Melchjorsen Jesper , Dagnaes-Hansen Frederik , Sørensen Uffe B. S. , Laursen Rune R. , Østergaard Lars , Søgaard Ole S. , Tolstrup Martin
Published: February 2012

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs, CpG ODN, are Toll-like receptor 9 agonists (TLR9a), which have been used as adjuvants in pneumococcal vaccines to improve antibody responses in immunodeficient patients. Here, we examined whether the coadministration of TLR9a with pneumococcal CRM197-conjugate vaccine enhances protection against pneumococcal colonization, the levels of antipolysaccharide antibodies, and the CD4+T-cell responses. Wild-type BALB/c mice and B-cell-deficient BALB/c Igh-Jtm1Dhumice were immunized twice with the following: (i) PCV alone; (ii) simultaneous PCV and TLR9a; (iii) PCV and then TLR9a, after a 48-h delay; (iv) TLR9a alone; and (v) phosphate-buffered saline. Nasopharyngeal protection, serum antibodies, CD4+T-cell responses, and clearance of bacteremia after intraperitoneal challenge withStreptococcus pneumoniae6B were evaluated. We found decreased nasopharyngeal protection againstS. pneumoniae6B colonization after simultaneous immunization with PCV and TLR9a compared to immunization with PCV alone in wild-type BALB/c mice (P= 0.037). A similar trend was observed in B-cell-deficient BALB/c Igh-Jtm1Dhumice. Simultaneous administration did not enhance antibody levels and lowered the CRM197-specific cytokine release of gamma interferon, interleukin-2 (IL-2), IL-5 and IL-13. Immunization with PCV and then TLR9a, after a 48-h delay, significantly improved nasopharyngeal protection compared to simultaneous administration (P= 0.011). Furthermore, delaying TLR9a delivery increased antibody titers compared to both simultaneous administration (P= 0.001) and PCV immunization alone (P= 0.026). In conclusion, the immunological and clinical impact of adjuvanting a pneumococcal conjugate vaccine (Prevnar; Pfizer) with a TLR9a is highly depended on timing of the adjuvant administration. Thus, careful timing of adjuvant administration may improve novel vaccine formulations.
Characterization of the Structurally Diverse N-Linked Glycans of Campylobacter Species
Authors: Jervis Adrian J. , Butler Jonathan A. , Lawson Andrew J. , Langdon Rebecca , Wren Brendan W. , Linton Dennis
Published: March 2012

The Gram-negative bacteriumCampylobacter jejuniencodes an extensively characterized N-linked protein glycosylation system that modifies many surface proteins with a heptasaccharide glycan. InC. jejuni, the genes that encode the enzymes required for glycan biosynthesis and transfer to protein are located at a singlepglgene locus. Similar loci are also present in the genome sequences of all otherCampylobacterspecies, although variations in gene content and organization are evident. In this study, we have demonstrated that onlyCampylobacterspecies closely related toC. jejuniproduce glycoproteins that interact with both aC. jejuniN-linked-glycan-specific antiserum and a lectin known to bind to theC. jejuniN-linked glycan. In order to further investigate the structure ofCampylobacterN-linked glycans, we employed anin vitropeptide glycosylation assay combined with mass spectrometry to demonstrate thatCampylobacterspecies produce a range of structurally distinct N-linked glycans with variations in the number of sugar residues (penta-, hexa-, and heptasaccharides), the presence of branching sugars, and monosaccharide content. These data considerably expand our knowledge of bacterial N-linked glycan structure and provide a framework for investigating the role of glycosyltransferases and sugar biosynthesis enzymes in glycoprotein biosynthesis with practical implications for synthetic biology and glycoengineering.
Prevalence and risk factors for forced or coerced sex among school-going youth: national cross-sectional studies in 10 southern African countries in 2003 and 2007
Authors: Andersson Neil , Paredes-Solís Sergio , Milne Deborah , Omer Khalid , Marokoane Nobantu , Laetsang Ditiro , Cockcroft Anne
Published: March 2012

Objectives

To study prevalence at two time points and risk factors for experience of forced or coerced sex among school-going youth in 10 southern African countries.

Design

Cross-sectional surveys, by facilitated self-administered questionnaire, of in-school youth in 2003 and 2007.

Setting

Schools serving representative communities in eight countries (Botswana, Lesotho, Malawi, Mozambique, Namibia, Swaziland, Zambia and Zimbabwe) in 2003 and with Tanzania and South Africa added in 2007.

Participants

Students aged 11–16 years present in the school classes.

Main outcome measures

Experience of forced or coerced sex, perpetration of forced sex.

Results

In 2007, 19.6% (4432/25 840) of female students and 21.1% (4080/21 613) of male students aged 11–16 years reported they had experienced forced or coerced sex. Rates among 16-year-olds were 28.8% in females and 25.4% in males. Comparing the same schools in eight countries, in an analysis age standardised on the 2007 Botswana male sample, there was no significant decrease between 2003 and 2007 among females in any country and inconsistent changes among males. In multilevel analysis using generalised linear mixed model, individual-level risk factors for forced sex among female students were age over 13 years and insufficient food in the household; school-level factors were a lower proportion of students knowing about child rights and higher proportions experiencing or perpetrating forced sex; and community-level factors were a higher proportion of adults in favour of transactional sex and a higher rate of intimate partner violence. Male risk factors were similar. Some 4.7% of female students and 11.7% of male students reported they had perpetrated forced sex. Experience of forced sex was strongly associated with perpetration and other risk factors for perpetration were similar to those for victimisation.

Conclusions

Forced or coerced sex remained common among female and male youth in 2007. Experience of sexual abuse in childhood is recognised to increase the risk of HIV infection. The association the authors found between forced sex and school-level factors suggests preventive interventions in schools could help to tackle the HIV epidemic in southern Africa.
Hypnotics' association with mortality or cancer: a matched cohort study
Authors: Kripke Daniel F , Langer Robert D , Kline Lawrence E
Published: February 2012

Objectives

An estimated 6%–10% of US adults took a hypnotic drug for poor sleep in 2010. This study extends previous reports associating hypnotics with excess mortality.

Setting

A large integrated health system in the USA.

Design

Longitudinal electronic medical records were extracted for a one-to-two matched cohort survival analysis.

Subjects

Subjects (mean age 54 years) were 10 529 patients who received hypnotic prescriptions and 23 676 matched controls with no hypnotic prescriptions, followed for an average of 2.5 years between January 2002 and January 2007.

Main outcome measures

Data were adjusted for age, gender, smoking, body mass index, ethnicity, marital status, alcohol use and prior cancer. Hazard ratios (HRs) for death were computed from Cox proportional hazards models controlled for risk factors and using up to 116 strata, which exactly matched cases and controls by 12 classes of comorbidity.

Results

As predicted, patients prescribed any hypnotic had substantially elevated hazards of dying compared to those prescribed no hypnotics. For groups prescribed 0.4–18, 18–132 and >132 doses/year, HRs (95% CIs) were 3.60 (2.92 to 4.44), 4.43 (3.67 to 5.36) and 5.32 (4.50 to 6.30), respectively, demonstrating a dose–response association. HRs were elevated in separate analyses for several common hypnotics, including zolpidem, temazepam, eszopiclone, zaleplon, other benzodiazepines, barbiturates and sedative antihistamines. Hypnotic use in the upper third was associated with a significant elevation of incident cancer; HR=1.35 (95% CI 1.18 to 1.55). Results were robust within groups suffering each comorbidity, indicating that the death and cancer hazards associated with hypnotic drugs were not attributable to pre-existing disease.

Conclusions

Receiving hypnotic prescriptions was associated with greater than threefold increased hazards of death even when prescribed <18 pills/year. This association held in separate analyses for several commonly used hypnotics and for newer shorter-acting drugs. Control of selective prescription of hypnotics for patients in poor health did not explain the observed excess mortality.
Defining impact of a rapid response team: qualitative study with nurses, physicians and hospital administrators
Authors: Benin Andrea L , Borgstrom Christopher P , Jenq Grace Y , Roumanis Sarah A , Horwitz Leora I
Published: March 2012

Objective

The objective of this study was to qualitatively describe the impact of a Rapid Response Team (RRT) at a 944-bed, university-affiliated hospital.

Methods

We analysed 49 open-ended interviews with administrators, primary team attending physicians, trainees, RRT attending hospitalists, staff nurses, nurses and respiratory technicians.

Results

Themes elicited were categorised into the domains of (1) morale and teamwork, (2) education, (3) workload, (4) patient care, and (5) hospital administration. Positive implications beyond improved care for acutely ill patients were: increased morale and empowerment among nurses, real-time redistribution of workload for nurses (reducing neglect of non-acutely ill patients during emergencies), and immediate access to expert help. Negative implications were: increased tensions between nurses and physician teams, a burden on hospitalist RRT members, and reduced autonomy for trainees.

Conclusions

The RRT provides advantages that extend well beyond a reduction in rates of transfers to intensive care units or codes but are balanced by certain disadvantages. The potential impact from these multiple sources should be evaluated to understand the utility of any RRT programme.
Time and temperature effects on geomembrane strain from a gravel particle subjected to sustained vertical force
Authors: Sabir A. , Brachman R.W.I.
Published: February 2012

Experimental data is reported that quantifies how time (up to 10 000 h) and temperature (from 22 to 85 °C) impact tensile strains in a 1.5 mm thick high-density polyethylene geomembrane — with a compressible clay liner beneath it — that are induced by an overlying gravel particle when subjected to a sustained vertical force. At an average applied stress of 250 kPa and clay water content of 16%, tensile strains were found to increase by 1.25 times as the temperature was increased from 22 to 55 °C after 1000 h. Similarly, strains were found to increase by factors between 1.2 to 1.3 as time was increased from 10 to 1000 h. Based on the measured data, time–temperature superposition (tTS) was then used to develop an approach to predict long-term geomembrane strains from gravel indentations. The tTS approach was validated against independent experiments conducted for 10 000 h (1.14 years) as it was found that the predicted strain of 19% was very close to the measured strain of 18%. Provided that the physical properties of the geomembrane do not decrease abruptly, the results suggest that the tTS approach developed can be used to provide estimates of long-term geomembrane strains.
Lower-bound calculations of the bearing capacity of eccentrically loaded footings in cohesionless soil
Authors: Krabbenhoft Sven , Damkilde Lars , Krabbenhoft Kristian
Published: February 2012

Lower-bound calculations based on the finite element method are used to determine the bearing capacity of a strip foundation subjected to a vertical, eccentric load on cohesionless soil with varying surcharges. The soil is assumed perfectly plastic following the Mohr–Coulomb failure criterion. The results are reported as tables and graphs showing the bearing capacity as a function of the eccentricity and surcharge. Normalised interaction diagrams in the vertical force versus moment plane have been produced. The results from the analysis are in reasonable agreement with existing methods for smaller eccentricities, whereas for greater eccentricities (e > 0.25B–0.3B, where B is the width of the foundation), the lower-bound values in general — and especially for greater surcharges — are considerably smaller than the bearing capacities predicted by existing methods. For the special case of no surcharge, the results are in very good agreement with results obtained by the effective-width approach originally proposed by Meyerhof.
OZI-ALLOWED TWO BODY ϒ DECAYS IN THE 3P0 MODEL WITH THE RELATIVISTIC WAVE FUNCTIONS
Authors: FU HUI-FENG , CHEN XIANG-JUN , WANG GUO-LI , WANG TIAN-HONG
Published: March 2012

We combine the Bethe–Salpeter method with the 3P0 model to describe OZI-allowed two body meson decays. In this combined method, the relativistic wave functions defined in the Salpeter equation show up in the decay amplitude of the 3P0 model automatically. We apply the method to OZI-allowed ϒ( 4S, 5S, 6S ) two body decays. The results are roughly consistent with the experimental data and the predictions of ϒ( 6S ) decays are given.
ORDERING GRAPH PRODUCTS OF GROUPS
Authors: CHISWELL I. M.
Published: March 2012

It is shown that a graph product of right-orderable groups is right orderable, and that a graph product of (two-sided) orderable groups is orderable. The latter result makes use of a new way of ordering free products of groups.