bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Jet Impingement on a Free Liquid Surface: PIV Study of the Turbulent Bubbly Two-Phase Flow
Authors: Hammad Khaled J.
Published: March 2011

The turbulent two-phase flow arising from the normal impingement of a round free-surface water jet on a horizontal air-water interface was experimentally studied. Due to the weakly viscous nature of the flow system under consideration, external perturbations or small variations in jet inflow conditions can lead to drastically different flow field characteristics under seemingly similar test conditions. In the current study, a fully developed turbulent jet, exiting a long pipe, ensured properly characterized inflow conditions. The study considered two jet inflow conditions; one entrained air and created a bubbly two-phase flow field while the other did not. Particle image velocimetry (PIV) was used to characterize the flow field beneath the interface, with and without air entrainment, for various nozzle-to-interface separation distances. Turbulent velocity fields of the continuous-phase and dispersed-phase were simultaneously measured in the developing flow region and presented using Reynolds decomposition into mean and fluctuating components. The mean and RMS velocities of the two-phase flow field were compared with velocity measurements obtained under single-phase conditions.
Lumped Parameter Modeling for Microfluidic Networks for Realizing Reconfigurable Nano-Optics Architectures
Authors: Kang Seok-Won , De Los Santos Hector J. , Banerjee Debjyoti
Published: March 2011

The geometry of a microchannel (or nanochannel) has a significant effect on pressure drop due to viscous friction. In this study, we investigate the flow behavior in microfluidic network architectures where the flow occurs from a straight square main channel to tributary channels. The flow phenomena are studied for various geometries such as circular, hexagonal, rectangular, rhombohedra, square, and triangular cross-sections. We calculate the filling time of microchannels by tracking the meniscus position in capillary driven flows. For this calculation, we implement a lumped parameter model based on electrical analogies between flow resistance and viscous friction factor. The simulation of this model is conducted using MATLAB GUI (Graphic User Interface) and it enables an end-user to perform parametric studies such as the effect of hydraulic diameter, length, geometry, number of tributary channels, and properties of the working fluid. The results of simulation are verified via Computational Fluid Dynamics (CFD) simulations (VOF method). The motivation of this study is to develop relevant design tools for predicting the flow behavior in different reconfigurable microfluidic/nanofluidic network architectures for the realization of programmable photonic band gap crystals (PBC).
Characterization and Optimization of a Three-Dimensional T-Type Micromixer for Convective Mixing Enhancement With Reduced Pressure Loss
Authors: Cortes-Quiroz Cesar A. , Azarbadegan Alireza , Zangeneh Mehrdad
Published: March 2011

Numerical simulations and experiments are used to evaluate the flow and mixing characteristics of a proposed convective 3-D T-type micromixer. The study presents a parametric study and performance optimization of this micromixer based on the variation of its geometry. To investigate the effect of design and operation parameters on the device performance, a systematic design and optimization methodology is applied; it combines Computational Fluid Dynamics (CFD) with an optimization strategy that integrates Design of Experiments (DOE), Surrogate modeling (SM) and Multi-Objective Genetic Algorithm (MOGA) techniques. The degree of mixing and the pressure loss in the mixing channel are the performance criteria to identify optimum designs at different Reynolds numbers (Re). The convective flow generated in the 3-D T-type micromixer drastically enhances mixing at Re > 100 by making the two fluids to roll up along the mixing channel. The resulting optimum designs are fabricated on polymethylmethacrylate (PMMA) by CNC micromachining. Experiments are carried out to visualize the streams of de-ionized water and aqueous fluorescein solution, by which the extent of mixing is determined, based on the standard deviation of fluorescein intensities on cross-section images. This study applies a systematic procedure for evaluation and optimization of a proposed 3-D T-mixer which has a configuration of channels that promote convective mixing since the two fluids come into contact. The methodology applied can also be used to efficiently modify and customize current micromixers.
Influence of Surfactants on Bubble Entrainment
Authors: Layman Christopher N. , Allen John S. , Sou In Mei
Published: March 2011

A drop impacting on a liquid surface may entrain a bubble resulting in sounds from the bubble oscillation in addition to that of the initial drop impact. This subject has received considerable interest with respect to the underwater sound produced by rain. The previous optical and acoustical studies have extensively examined the role of drop size and impact velocity as well entrainment formation mechanisms. However, the role of surfactants on the liquid surface has received less attention especially with respect to sound production. One previous study [1] of two different surfactants (Kodak Photoflo and a sulfo detergent) reports that these suppress entrainment resulting in diminished or negligible bubble noise. However, we have found bubble entrainment and acoustic emissions associated with the addition of a heptane layer on the water surface. Using a synchronized hydrophone and a high-speed camera, acoustical and optical data of the bubble drop dynamics were obtained. Particle image velocimetry (PIV) was also utilized to measure the surface velocity produced by the drop. These results show a significant difference in the drop rebound and subsequent fluid column dynamics, which results in a dual acoustic emission for the surfactant case.
Flapping Instability of an Atomized Liquid Jet
Authors: Matas Jean-Philippe , Cartellier Alain
Published: March 2011

We present an experimental study of the flapping instability which appears when a coaxial liquid jet is atomized by a cocurrent fast gas stream. When primary atomization does not lead to a total break-up of the liquid jet, it undergoes a large-wavelength instability, characterized by very large amplitude oscillations, and can break into large liquid fragments whose typical size is the jet diameter. These large liquid fragments, and consequently the flapping instability, are to be avoided in applications related to combustion where liquid droplets need to be as small as possible. We carried out experiments with air and water coaxial jets, with a gas/liquid velocity ratio of order 50. We studied the consequence of the flapping instability on the break-up of the liquid jet. Measurements of the frequency of the instability were carried out. We suggest a mechanism where the flapping instability could be triggered by non axisymmetrical KH modes.
Response Surface Modeling of a Large Break Loss of Coolant Accident With Comparisons to Order Statistics Approaches
Authors: French Andrew B.
Published: March 2011

NUREG/CR-5249 “Quantifying Reactor Safety Margins Application of Code Scaling, Applicability, and Uncertainty Evaluation Methodology to a Large Break, Loss-of-Coolant Accident” provides the general methodologies to be used in the development of realistic loss of coolant safety analyses. The objective of this paper is to start with NUREG/CR-5249 and develop a modified methodology. The modified approach will include a response surface, model adequacy checks, and development of the 95/95% confidence peak clad temperature cumulative distributions function. The response surface model will then be used to develop simulated results and conclusions about the order statistics best estimate approach. All work is conducted using a verified safety analysis input deck and RELAP as the thermal hydraulic best estimate analysis code. The objective of the order statistics comparison is to investigate the number of cases in which the maximum PCT, in a simulated order statistics approach, falls below the 95th percentile value of the distribution and to assess the standard deviation in the maximum peak clad temperature of order statistics sets. Although order statistics may be a more economic approach to satisfying regulatory requirements, response surface models have several benefits that can complement the use of order statistics. The primary benefit is the insight gained into which parameters are most important in determining the peak clad temperature. This is of particular value to the licensee in convincing the regulator that its analysis is robust. The disadvantage is the number of runs required to develop the models. If we examine the main effects, the most significant input parameter is pipe break size. In support of a proposed modification to 10CFR50.46, the U.S. Nuclear Regulatory Commission undertook an expert elicitation to assess the change in frequency of pipe break accidents as a function of break size. The result of that elicitation was a probability density function that decreases approximately as (pipe diameter)−1.5 in the region of large pipe diameters. Because break diameter is shown to be such a large contributor to PCT by the response surface, it is evident that calculated PCT could be substantially reduced if credit were given for this form of the uncertainty distribution rather than for the flat distribution used in the analysis (and industry).
Experimental and CFD Investigations to Evaluate the Effects of Fluid Viscosity and Particle Size on Erosion Damage in Oil and Gas Production Equipment
Authors: Okita Risa , Zhang Yongli , McLaury Brenton S. , Shirazi Siamack A. , Rybicki Edmund F.
Published: March 2011

Zhang et al (2006) utilized CFD to examine the validity of erosion models that have been implemented into CFD codes to predict solid particle erosion in air and water for Inconel 625. This work is an extension of Zhang’s work and is presented as a step toward obtaining a better understanding of the effects of fluid viscosity and sand particle size on measured and calculated erosion rates. The erosion rates of Aluminum 6061-T6 were measured for direct impingement conditions of a submerged jet. Fluid viscosities of 1, 10, 25, and 50 cP and sand particle sizes of 20, 150, and 300 μm were tested. The average fluid speed of the jet was maintained at 10 m/s. Erosion data show that erosion rates for the 20 and 150 μm particles are reduced as the viscosity is increased, while surprisingly the erosion rates for the 300 μm particles do not seem to change much for the higher viscosities. For all viscosities considered, larger particles produced higher erosion rates, for the same mass of sand, than smaller particles. Concurrently, an erosion equation has been generated based on erosion testing of the same material in air. The new erosion model has been compared to available models and has been implemented into a commercially available CFD code to predict erosion rates for a variety of flow conditions, flow geometries, and particle sizes. Since particle speed and impact angle greatly influence erosion rates of the material, calculated particle speeds were compared with measurements. Comparisons reveal that, as the particles penetrate the near wall shear layer, particles in the higher viscosity liquids tend to slow down more rapidly than particles in the lower viscosity liquids. In addition, CFD predictions and particle speed measurements are used to explain why the erosion data for larger particles is less sensitive to the increased viscosities.
Mixing Layer Growth Response to Inflow Forcing With Random Phase Shift
Authors: Ko Jordan , Lucor Didier , Garnier Josselin
Published: March 2011

We study the sensitivity of the formation and the evolution of large-scale coherent structures in spatially developing plane mixing layers to uncertainties in the inflow forcing phase shifts. Instead of examining the mixing layer growth at discrete phase values, a complete response is determined by treating the phase shift as periodic and uniformly distributed random variables. The Fourier Chaos expansion (FCE) is used to decompose the stochastic solution in the abstract random space and the coefficients are determined by the discrete Fourier transformation (DFT). The statistical moments and quantiles of pertinent physical measures were determined. In the bimodal perturbation case, the vortex interactions are sensitive to only a small range of phase differences where large downstream variations in mixing layer growths are observed. In the tri–modal perturbation case, mixing layer growth is especially sensitive to the phase difference between the fundamental and the subharmonic modes immediately downstream from the inlet. Near the downstream location with subharmonic vortices roll up, an increase of the influence of the phase difference between the subharmonic modes can be observed. In both cases, the stochastic phase differences between the perturbation modes are delayed further downstream in comparison to the stochastic perturbation magnitudes. Quantiles of discrete vortex pairing events and different mixing layer length scales are also estimated.
Application of the UMAE Methodology for the Uncertainty Evaluation in Support to the EOP Background Analysis
Authors: Bajs Tomislav , Konjarek Damir , Ivekovic´ Ilijana
Published: March 2011

Validation of EOPs (Emergency Operating Procedures) relies on the best-estimate analysis of the transient scenarios. In order to cover associated uncertainties, usually limited number of sensitivity studies is performed for the development of the EOPs in order to identify possible plant states and associated parameters relevant for operator actions. Recently, developed methodologies for the uncertainty evaluation made it possible to evaluate directly uncertainties with the respect to the scenarios analyzed. UMAE (Uncertainty Methodology based on Accuracy Extrapolation) uncertainty methodology has been applied for development of function restoration EOPs. More specifically, Inadequate Core Cooling (ICC) LOCA (Loss of Coolant Accident) scenario has been analyzed using best estimate transient analysis code RELAP5/SCDAPSIM code. Time window for successful operator action has been evaluated following 4.0″ cold leg break near the Reactor Pressure Vessel (RPV) in a 2-loop PWR plant.
Sinuous Streak Instability and Breakdown in a Blasius Boundary Layer
Authors: Watmuff Jonathan H.
Published: March 2011

A narrow low-speed streamwise streak is deliberately introduced into an otherwise extremely spanwise uniform Blasius boundary layer. The streak shares many of the characteristics of Klebanoff modes known to be responsible for bypass transition at moderate Free Stream Turbulence (FST) levels. However, for the low background disturbance level of the free stream (u/U1 < 0.05%), the layer remains laminar to the end of the test section (Rx = 1.4 × 106) and there is no evidence of bursting or other phenomena associated with breakdown to turbulence. A harmonic disturbance is used to excite a sinuous form of instability, which grows over a considerable streamwise distance before breakdown of the streak occurs, which leads to the formation of a turbulent wedge. Detailed measurements show that new streaks are formed on either side during the breakdown process. The characteristics of the wedge are examined over a considerable streamwise distance. A similar mechanism appears to be responsible for the spanwise growth of the wedge since a span-wise succession of new streaks is observed in the early stages of its development.
Observing Human Blood Cells in Flow Through Microchannels
Authors: Goldsmith Harry L.
Published: March 2011

For the rheologist, blood is essentially a concentrated suspension of biconcave 8-μm diameter red cells (40–45% by volume) that circulates within the body in vessels from 25 mm down to 5 μm diameter. Here, we describe in vitro tracking of blood cells in a traveling microtube apparatus and in a counter-rotating micro cone-plate device at low Reynolds numbers, Re. Observations of the flow behavior of individual red cells reveal a marked and continuously changing deformation and interaction of the cells in shear, and this, together with their migration away from the vessel wall accounts for the low whole blood overall viscosity compared to other concentrated suspensions and emulsions. Red cells also strongly affect the flow behavior and interactions of platelets and of white cells, which although present at much lower concentrations (0.3% by volume), play key roles in thrombosis, hemostasis, and inflammation. Studies of the kinetics of the formation and break-up of receptor-ligand bonds between membranes of platelets and of white cells in shear flow revealed single bond strengths of 50 −200 nN. Such micro particle image velocimetry (μPIV) studies have recently been considerably refined and extended to in vivo vessels such as postcapillary venules. Using submicron fluorescent latex spheres, the existence of an impermeable and hydrodynamically effective surface layer (< 0.5 μm thick) extending out from the vessel endothelium has been confirmed. The lecture is illustrated by movies of blood flow in vitro and in vivo.
Microelectromechanical system-based vacuum gauge for measuring pressure and outgassing rates in miniaturized vacuum microelectronic devices
Authors: Kuljic R. , Chang J. , Jayapratha N. , Dankovic T. , Banerjee K. , Feinerman A. , Busta H.
Published: March 2011

Cr/Au meander-shaped resistors were fabricated on 0.2 μm thick square-shaped silicon nitride diaphragms with diaphragm dimensions ranging from 0.775 to 2.275 mm. The performance of these sensors was measured in a vacuum chamber as a function of resistor powers from 0.5 to 3 mW at pressures ranging from 2×10−4 to 760 Torr. The lengths of the meander-shaped resistors increase from 5.5 mm for the 0.775 mm diaphragm to 33.6 mm for the 2.275 mm diaphragm devices. It is shown that the pressure dependence of the devices is governed by the kinetic gas theory and that the devices can measure pressures from about 10 to 1×10−3 Torr. At a resistor power of 2 mW at 760 Torr, the 2.275 mm diaphragm device, which has the largest sensing area, exhibits the highest sensitivity.
Growth model for plasma-assisted molecular beam epitaxy of N-polar and Ga-polar InxGa1−xN
Authors: Nath Digbijoy N. , Gür Emre , Ringel Steven A. , Rajan Siddharth
Published: March 2011

The authors have developed a comprehensive model for the growth of N-polar and Ga-polar InxGa1−xN by N2 plasma-assisted molecular beam epitaxy. GaN films of both polarities were coloaded and InxGa1−xN was grown in the composition range of 0.14<x<0.59 at different growth temperatures keeping all other conditions identical. The compositions were estimated by triple-axis ω-2θ x-ray diffraction scans as well as by room temperature photoluminescence measurements. The dependence of the In composition x in InxGa1−xN on growth temperature and the flux of incoming atomic species is explained using a comprehensive growth model which incorporates desorption of atomic fluxes as well as decomposition of InN component of InxGa1−xN. The model was found to be in good agreement with the experimental data for InxGa1−xN of both polarities. A N-polar In0.31Ga0.69N/In0.05Ga0.95N multi-quantum-well structure grown with conditions predicted by our growth model was found to match the compositions of the active layers well besides achieving a smooth surface morphology at the quantum-well/barrier interface. The understanding of growth kinetics presented here will guide the growth of InxGa1−xN for various device applications in a wide range of growth conditions.
Processing-structure-property relationships in electron beam physical vapor deposited yttria stabilized zirconia coatings
Authors: Rao D. Srinivasa , Valleti Krishna , Joshi S. V. , Janardhan G. Ranga
Published: March 2011

The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented.
Effect of annealing on the electrical properties of ZnO crystals grown by chemical vapor transport
Authors: Abe Koji , Miura Masaaki , Oiwa Masanori
Published: March 2011

Electrical properties of ZnO crystals annealed at 600 °C in H2, O2, and Ar have been investigated. The two donors (D1 and D2) with the ionization energies of ED1∼0.043 eV and ED2=0.08 eV and a compensating acceptor were observed in the as-grown and annealed samples. There was no significant change in electrical properties of the sample annealed in H2, while annealing in O2 and Ar affected the electron concentration. The decrease of the D1 donor concentration and the increase of the compensating acceptor concentration were observed in the samples annealed in O2. The electron mobility for the sample annealed in O2 decreased because of the increase of the compensating acceptor concentration.
‘It Has to Go Down a Little, in Order to Go Around’ — Revisiting Feynman on the Gyroscope
Authors: Kostov Svilen , Hammer Daniel
Published: March 2011

In this paper we show that with the help of accessible, teaching-quality equipment, some interesting and important details of the motion of a gyroscope, which are typically overlooked in introductory courses, can be measured and compared to theory. We begin by deriving a simple relation between the dip angle of a gyroscope released from rest and its precession velocity. We then describe an experiment that measures these parameters. The data are in excellent agreement with the theoretical prediction. The idea for this project was suggested by the discussion of gyroscopic motion in The Feynman Lectures on Physics. Feynman's (Fig. 1) conclusion (stated in colloquial language and quoted in the title) is confirmed and, in addition, conservation of angular momentum, which underlies this effect, is quantitatively demonstrated.
Can a String's Tension Exert a Torque on a Pulley?
Authors: Krause Dennis E. , Sun Yifei
Published: March 2011

A typical textbook problem in rotational dynamics involves calculating the angular acceleration of a massive pulley due to a string, such as in the example shown in Fig. 1. The string is assumed to be massless and to move without slipping over the pulley, which is mounted on a frictionless axle. If TL and TR are the tensions pulling at the left and right edges of the pulley (see Fig. 1), respectively, the net torque on the pulley is then τnet = (TL - TR)R, where R is the radius of the pulley. (It is assumed that positive torque corresponds to the counterclockwise direction.) While this analysis, which is typical of what is found in many introductory physics texts,1 is correct, it should raise several questions in the mind of a student. First, since most texts argue that the tension everywhere in a massless string is constant,2 why is TL ≠ TR? Second, since tension is an internal force (except at the ends of the string, which are obviously not tied to the pulley),3 how can tension exert a force and torque on a pulley? In this paper, we will address these questions, which are overlooked in most textbook treatments of this problem whose approach appears inconsistent with the concepts presented elsewhere in the text.
What physics principle can I teach with this?
Authors: Dolan Paul
Published: March 2011

If you are a physics teacher, you are already a more critical observer of your surroundings than are most people, wondering what things do and how they work. Many of you may have spent time when you were younger taking apart (and sometimes reassembling) things like clocks, telephones, tractors, computers, and, in my case, a cuckoo clock (which functions at least as well as it did before my dad and I disassembled it—and at least the “cuckoo” function it was missing was recovered).
Complex Multicolor Tilings and Critical Phenomena in Tetraphilic Liquid Crystals
Authors: Zeng Xiangbing , Kieffer Robert , Glettner Benjamin , Nürnberger Constance , Liu Feng , Pelz Karsten , Prehm Marko , Baumeister Ute , Hahn Harald , Lang Heinrich , Gehring Gillian A. , Weber Christa H. M. , Hobbs Jamie K. , Tschierske Carsten , Ungar Goran
Published: March 2011

X-shaped molecules undergo reversible thermal transitions between phase-separated and mixed states.
Creating Favorable Geometries for Directing Organic Photoreactions in Alkanethiolate Monolayers
Authors: Kim Moonhee , Hohman J. Nathan , Cao Yang , Houk Kendall N. , Ma Hong , Jen Alex K.-Y. , Weiss Paul S.
Published: March 2011

Molecules align in molecular overlayers for photodimerization reactions that would be disfavored in solution.
Aerosol Chemistry and the Deepwater Horizon Spill
Authors: Coe Hugh
Published: March 2011

Airborne observations reveal the role of less volatile organic compounds in forming atmospheric aerosols.
The End of the World Is Flat
Cycles of Time
An Extraordinary New View of the Universe

by Roger Penrose

Bodley Head, London, 2010. 300 pp. £25, C$37.95. ISBN 9780224080361. Forthcoming (May) from Knopf, New York. $28.95. ISBN 9780307265906.
Authors: Bousso Raphael
Published: March 2011

From the second law of thermodynamics and the "light-cone geometry of space-time," Penrose argues that the end of our current expanding universe will serve as the big bang of a new one.
Crise de Foie, Redux?
Authors: Moore David D.
Published: March 2011

Two nuclear factors work in concert to regulate circadian expression of metabolic genes.
Listeria
Unwinds Host DNA
Authors: Rohde John R.
Published: March 2011

A bacterium uses a viral strategy to manipulate the host cell immune response and optimize conditions for infection.
The Deep Social Structure of Humankind
Authors: Chapais Bernard
Published: March 2011

Primatology and anthropology converge on the uniqueness of human society.
Rhodopsin as Thermosensor?
Authors: Minke Baruch , Peters Maximilian
Published: March 2011

A molecule that senses light is also important for temperature discrimination.
Celebrating the Culture of Science
Authors: Durant John , Ibrahim Alaa
Published: March 2011

There is an increasing worldwide consensus on the vital importance of Science for personal, social, economic, and political development. This has spurred many countries to increase their investments in science and technology. But funding research is not enough: Nations must also promote cultures that celebrate science and its values of reasoning, openness, tolerance, and respect for evidence, just as they celebrate the arts and humanities that enrich everyone's lives. Not only formal education but informal outreach is critical in achieving this goal. Today, there is a great deal of creative experimentation with different methods of engaging the public with science. Our own experiences in organizing science festivals in the United States and Egypt illustrate the potential of one important form of public engagement.
Counting the Dead in Afghanistan
Authors: Bohannon John
Published: March 2011

A military data set of civilian casualties, provided exclusively to
Science
, indicates that the war has become more lethal to the Afghan population, largely because of indiscriminate insurgent attacks.
War as a Laboratory For Trauma Research
Authors: Bohannon John
Published: March 2011

The military is sending scientists onto the battlefield to find ways to improve emergency medicine, but the research faces a practical and ethical minefield.
Results from a Randomized Clinical Trial of Coadministration of RotaTeq, a Pentavalent Rotavirus Vaccine, and NeisVac-C, a Meningococcal Serogroup C Conjugate Vaccine
Authors: Vesikari Timo , Karvonen Aino , Borrow Ray , Kitchin Nick , Baudin Martine , Thomas Stéphane , Fiquet Anne
Published: March 2011

RotaTeq (Merck & Co. Inc./Sanofi Pasteur MSD) is a three-dose, oral pentavalent rotavirus vaccine for the immunization of infants from 6 weeks of age for the prevention of rotavirus gastroenteritis. The primary objective of the present trial was to demonstrate that RotaTeq can be coadministered with meningococcal serogroup C conjugate vaccine (MenCC; NeisVac-C; Baxter Healthcare) to healthy infants without impairing the protective immune responses to MenCC. This was an open-label, randomized, comparative study conducted in Finland. The study was designed to assess concomitant versus sequential administration of RotaTeq and MenCC on the immune response to both vaccines. Healthy infants (
n
= 247), aged 6 to 7 weeks, were recruited. Coadministration of MenCC with RotaTeq was noninferior to sequential administration for the seroprotection rate against meningococcal serogroup C (the proportion of infants with a serum bactericidal antibody titer using baby rabbit complement of ≥8 was 100% in both groups). The other responses to MenCC (titer of ≥1:128, ≥4-fold increase in titer, and geometric mean titers [GMTs]) and the responses to RotaTeq (IgA and SNA response to G1 to G4 and P1A[8], GMTs, and ≥3-fold increase in titer) were comparable between groups, including a ≥3-fold IgA increase in >96% of the infants in both groups. Concomitant administration of the first doses of MenCC, diphtheria and tetanus toxoids and acellular pertussis vaccine, inactivated poliovirus vaccine, and
Haemophilus influenzae
type b conjugate vaccine (DTaP-IPV-Hib), and RotaTeq was associated with a higher rate of vomiting and diarrhea than concomitant administration of MenCC and DTaP-IPV-Hib, but that was not observed after the second concomitant administration. The convenience of concomitant administration of RotaTeq and MenCC may, however, outweigh the additive effect of mostly mild adverse events reported after the individual administration of each vaccine. These results support the coadministration of RotaTeq and MenCC.
Accurate and Practical Identification of 20 Fusarium Species by Seven-Locus Sequence Analysis and Reverse Line Blot Hybridization, and an In Vitro Antifungal Susceptibility Study
Authors: Wang He , Xiao Meng , Kong Fanrong , Chen Sharon , Dou Hong-Tao , Sorrell Tania , Li Ruo-Yu , Xu Ying-Chun
Published: March 2011

Eleven reference and 25 clinical isolates of
Fusarium
were subject to multilocus DNA sequence analysis to determine the species and haplotypes of the fusarial isolates from Beijing and Shandong, China. Seven loci were analyzed: the translation elongation factor 1 alpha gene (
EF-1
α); the nuclear rRNA internal transcribed spacer (ITS), large subunit (LSU), and intergenic spacer (IGS) regions; the second largest subunit of the RNA polymerase gene (
RPB2
); the calmodulin gene (
CAM
); and the mitochondrial small subunit (mtSSU) rRNA gene. We also evaluated an IGS-targeted PCR/reverse line blot (RLB) assay for species/haplotype identification of
Fusarium
. Twenty
Fusarium
species and seven species complexes were identified. Of 25 clinical isolates (10 species), the
Gibberella
(
Fusarium
)
fujikuroi
species complex was the commonest (40%) and was followed by the
Fusarium solani
species complex (FSSC) (36%) and the
F. incarnatum-F. equiseti
species complex (12%). Six FSSC isolates were identified to the species level as FSSC-3+4, and three as FSSC-5. Twenty-nine IGS, 27
EF-1
α, 26
RPB2
, 24
CAM
, 18 ITS, 19 LSU, and 18 mtSSU haplotypes were identified; 29 were unique, and haplotypes for 24 clinical strains were novel. By parsimony informative character analysis, the IGS locus was the most phylogenetically informative, and the rRNA gene regions were the least. Results by RLB were concordant with multilocus sequence analysis for all isolates. Amphotericin B was the most active drug against all species. Voriconazole MICs were high (>8 μg/ml) for 15 (42%) isolates, including FSSC. Analysis of larger numbers of isolates is required to determine the clinical utility of the seven-locus sequence analysis and RLB assay in species classification of fusaria.
Comparison of Strain Typing Results for Clostridium difficile Isolates from North America
Authors: Tenover Fred C. , Åkerlund Thomas , Gerding Dale N. , Goering Richard V. , Boström Therése , Jonsson Anna-Maria , Wong Edith , Wortman Alan T. , Persing David H.
Published: March 2011

Accurate strain typing is critical for understanding the changing epidemiology of
Clostridium difficile
infections. We typed 350 isolates of toxigenic
C. difficile
from 2008 to 2009 from seven laboratories in the United States and Canada. Typing was performed by PCR-ribotyping, pulsed-field gel electrophoresis (PFGE), and restriction endonuclease analysis (REA) of whole-cell DNA. The Cepheid Xpert
C. difficile
test for presumptive identification of 027/NAP1/BI isolates was also tested directly on original stool samples. Of 350 isolates, 244 (70%) were known PCR ribotypes, 224 (68%) were 1 of 8 common REA groups, and 187 (54%) were known PFGE types. Eighty-four isolates typed as 027, NAP1, and BI, and 83 of these were identified as presumptive 027/NAP1/BI by Xpert
C. difficile
. Eight additional isolates were called presumptive 027/NAP1/BI by Xpert
C. difficile
, of which three were ribotype 027. Five PCR ribotypes contained multiple REA groups, and three North American pulsed-field (NAP) profiles contained both multiple REA groups and PCR ribotypes. There was modest concordance of results among the three methods for
C. difficile
strains, including the J strain (ribotype 001 and PFGE NAP2), the toxin A-negative 017 strain (PFGE NAP9 and REA type CF), the 078 animal strain (PFGE NAP7 and REA type BK), and type 106 (PFGE NAP11 and REA type DH). PCR-ribotyping, REA, and PFGE provide different but overlapping patterns of strain clustering. Unlike the other methods, the Xpert
C. difficile
027/NAP1/BI assay gave results directly from stool specimens, required only 45 min to complete, but was limited to detection of a single strain type.
Recent Amplification of the Kangaroo Endogenous Retrovirus, KERV, Limited to the Centromere
Authors: Ferreri Gianni C. , Brown Judith D. , Obergfell Craig , Jue Nathaniel , Finn Caitlin E. , O'Neill Michael J. , O'Neill Rachel J.
Published: March 2011

Mammalian retrotransposons, transposable elements that are processed through an RNA intermediate, are categorized as short interspersed elements (SINEs), long interspersed elements (LINEs), and long terminal repeat (LTR) retroelements, which include endogenous retroviruses. The ability of transposable elements to autonomously amplify led to their initial characterization as selfish or junk DNA; however, it is now known that they may acquire specific cellular functions in a genome and are implicated in host defense mechanisms as well as in genome evolution. Interactions between classes of transposable elements may exert a markedly different and potentially more significant effect on a genome than interactions between members of a single class of transposable elements. We examined the genomic structure and evolution of the kangaroo endogenous retrovirus (KERV) in the marsupial genusMacropus. The complete proviral structure of the kangaroo endogenous retrovirus, phylogenetic relationship among relative retroviruses, and expression of this virus in bothMacropus rufogriseusandM. eugeniiare presented for the first time. In addition, we show the relative copy number and distribution of the kangaroo endogenous retrovirus in theMacropusgenus. Our data indicate that amplification of the kangaroo endogenous retrovirus occurred in a lineage-specific fashion, is restricted to the centromeres, and is not correlated with LINE depletion. Finally, analysis of KERV long terminal repeat sequences using massively parallel sequencing indicates that the recent amplification inM. rufogriseusis likely due to duplications and concerted evolution rather than a high number of independent insertion events.
Open Reading Frames Carried on UL/b′ Are Implicated in Shedding and Horizontal Transmission of Rhesus Cytomegalovirus in Rhesus Monkeys
Authors: Oxford Kristie L. , Strelow Lisa , Yue Yujuan , Chang W. L. William , Schmidt Kimberli A. , Diamond Don J. , Barry Peter A.
Published: March 2011

Implicit with the use of animal models to test human cytomegalovirus (HCMV) vaccines is the assumption that the viral challenge of vaccinated animals reflects the anticipated virus-host interactions following exposure of vaccinated humans to HCMV. Variables of animal vaccine studies include the route of exposure to and the titer of challenge virus, as well as the genomic coding content of the challenge virus. This study was initiated to provide a better context for conducting vaccine trials with nonhuman primates by determining whether the
in vivo
phenotype of culture-passaged strains of rhesus cytomegalovirus (RhCMV) is comparable to that of wild-type RhCMV (RhCMV-WT), particularly in relation to the shedding of virus into bodily fluids and the potential for horizontal transmission. Results of this study demonstrate that two strains containing a full-length UL/b′ region of the RhCMV genome, which encodes proteins involved in epithelial tropism and immune evasion, were persistently shed in large amounts in bodily fluids and horizontally transmitted, whereas a strain lacking a complete UL/b′ region was not shed or transmitted to cagemates. Shedding patterns exhibited by strains encoding a complete UL/b′ region were consistent with patterns observed in naturally infected monkeys, the majority of whom persistently shed high levels of virus in saliva for extended periods of time after seroconversion. Frequent viral shedding contributed to a high rate of infection, with RhCMV-infected monkeys transmitting virus to one naïve animal every 7 weeks after introduction of RhCMV-WT into an uninfected cohort. These results demonstrate that the RhCMV model can be designed to rigorously reflect the challenges facing HCMV vaccine trials, particularly those related to horizontal transmission.
Delivery technique plays an important role in determining vessel wall apposition of the Enterprise self-expanding intracranial stent
Authors: Heller Robert S , Malek Adel M
Published: March 2011

Background

The Enterprise (EN) vascular reconstruction device is a self-expanding nitinol stent used as adjunctive support in wide-necked aneurysm coiling. We sought to evaluate the effect of deployment technique on how well the EN stent conforms to the vessel wall around a curve.

Methods

A flow model consisting of a 3.5 mm diameter silicone tube forming a 7 mm radius curve was visualized using high-resolution flat-panel CT (FPCT; DynaCT). EN stents (4.5 mm×22 mm) were deployed using three methods: (1) microcatheter pull-back, (2) delivery microwire push and (3) a combination of both methods so as to keep the microcatheter tip centered within the lumen during deployment. FPCT images were visualized using multiplanar reconstruction for evidence of incomplete stent apposition (ISA).

Results

FPCT revealed a critical role for deployment method in stent–wall apposition as noted by the development of a crescent-shaped gap between the stent and the wall. Specifically, the manufacturer-recommended microcatheter pull-back unsheathing technique (method 1) resulted in outer curve ISA, while the microwire push technique (method 2) led to inner curve ISA. Using method 3 in a dynamic push–pull manner minimized both inner and outer curve ISA.

Conclusion

The deployment method used to deliver the EN vascular reconstruction device plays a critical role in determining how well its struts appose the vessel wall in vitro. This characteristic must be taken into account when deploying this flexible low-profile stent to avoid ISA in even mildly tortuous anatomy given the possible link between stent malapposition and thromboembolic complications.
Endotoxin exposure,CD14and wheeze among farmers: a gene–environment interaction
Authors: Smit Lidwien A M , Heederik Dick , Doekes Gert , Koppelman Gerard H , Bottema Renske W B , Postma Dirkje S , Wouters Inge M
Published: March 2011

Objectives

Endotoxin-exposed workers are at an increased risk of non-atopic asthma and lung-function decline. Genetic variants may influence susceptibility to these effects. The objective of the present study was to assess whether the association between occupational endotoxin exposure and wheeze is modified by innate immunity gene variants.

Methods

Twenty-four single nucleotide polymorphisms (SNPs) inCD14, Toll-like receptor 4 (TLR4),TLR2,MD2andMyD88were genotyped in 408 agricultural workers with spirometry and questionnaire data on asthma symptoms available. Personal airborne endotoxin exposure levels were estimated in 249 exposure measurements.

Results

The association between endotoxin exposure and wheeze was modified by threeCD14SNPs: -260 C/T (rs2569190), -1247 T/C (rs2569191) and -1721 A/G (rs2915863), and oneMD2SNP (rs10808798 T/C). In individuals carrying theCD14andMD2major allele variants, the prevalence of wheeze increased with increasing endotoxin concentration, whereas this was the opposite in minor allele homozygotes. Interaction between endotoxin exposure and genotype was statistically significant under the best-fitting recessive model (p=0.05 to 0.006). Correction for multiple comparisons resulted in marginally significant p values for interaction (p<0.06) forCD14-260 C/T and -1247 T/C, and forMD2rs10808798 T/C. TheCD14SNPs appeared to modify associations between endotoxin exposure and forced expiratory volume in 1 s in a similar direction (p interaction=0.07 to 0.15).

Conclusions

The association between occupational endotoxin exposure and wheeze in agricultural workers was significantly modified by genetic variants inCD14andMD2. Our study suggests that carriers of the functionalCD14/-260 C allele are more responsive to endotoxin exposure than T allele homozygotes.
A scientific and psychosocial environmental investigation tool: the Meeting, Understanding, Surveillance, Toxicology, Evaluation and Reporting (MUSTER) model
Authors: Hyland Jackie , Donnelly Peter
Published: March 2011

Background

Although there is a wealth of information on hazards in the environment and robust systems for measuring environmental pollutants, there is limited guidance for practitioners in any field of health which addresses the psychosocial element of environmental investigations. Investigating environmental concerns is, however, necessary. It is possible that health may be affected by a previously unknown contaminate or may potentially be affected if action is not taken.

Methods

To address this, a model for the integration of scientific and psychosocial considerations into a systematic, complainant centred approach for practitioners undertaking environmental investigations has been developed for use by public health professionals, environmental health officers, occupational health professionals, and general practitioners, among others. The process involves Meeting and interviewing individual complainants, Understanding individual and local concerns, reviewing Surveillance and Toxicological data, Evaluating findings, and Reporting on findings—the MUSTER model.

Results

The MUSTER model proposes a method of investigation at an individual level which addresses physical, and psychosocial concerns. It is presented with real life case studies which demonstrate the importance of addressing each aspect. The model incorporates what is already known about health and environmental investigations but presents this in an easy-to-remember mnemonic. While the model has been derived from public health investigations its application is equally suited for any practitioner undertaking a health related environmental investigation.

Conclusions

The MUSTER model should be disseminated widely so that there is a robust, evidence based and consistent approach to environmental investigations which satisfies complainants, enhances practitioner knowledge base, and improves communication.
Hypoglycaemia following a mixed meal in eating disorder patients
Authors: Hart Susan , Abraham Suzanne , Franklin Richard C , Twigg Stephen M , Russell Janice
Published: March 2011

Objective

To describe the incidence of hypoglycaemia, and variables associated with hypoglycaemia, in eating disorder patients following a mixed meal stimulus.

Methods

Postprandial blood glucose values of patients admitted to a specialist eating disorder hospital for treatment of an eating disorder between 2000 and 2006 were reviewed and compared to body mass index (BMI), electrolytes, and weight losing behaviours. Analysis of variance (ANOVA) and stepwise logistic regression were undertaken.

Results

22% of patients had postprandial glucose values ≤3.5 mmol/l (63 mg/dl). Only low BMI significantly predicted postprandial hypoglycaemia.

Conclusion

Clinicians should be aware that postprandial hypoglycaemia is a common finding in eating disorders patients receiving inpatient treatment. As hypoglycaemia is predicted by low BMI, weight restoration is a priority for treatment in patients experiencing hypoglycaemia. Future research should investigate the nutrient composition of refeeding regimens and whether altering the macronutrient composition attenuates the presence of hypoglycaemia. Investigation is warranted in a community sample of eating disorder patients to see if this finding is replicated in non-hospitalised patients.
THERMODYNAMICS OF GAUSS–BONNET–BORN–INFELD BLACK HOLES IN AdS SPACE
Authors: ZOU DECHENG , YANG ZHANYING , YUE RUIHONG , LI PENG
Published: March 2011

We construct solutions of a model which includes the Gauss–Bonnet and Born–Infeld terms for various horizon topologies (k = 0, ±1), and then the mass, temperature, entropy, and heat capacity of black holes are computed. For the sake of simplicity, we perform the stability analysis of five-dimensional topological black holes in AdS space.
THE FRIEDMANN EQUATION IN MODIFIED ENTROPY-AREA RELATION FROM ENTROPY FORCE
Authors: LIU BIN , DAI YUN-CHUAN , HU XIAN-RU , DENG JIAN-BO
Published: March 2011

According to the formal holographic principle, a modification to the assumption of holographic principle in Verlinder's investigation of entropy force is obtained. A more precise relation between entropy and area in the holographic system is proposed. With the entropy corrections to the area-relation, we derivate Newton's laws and Einstein equation with a static spherically symmetric holographic screen. Furthermore, we derived the correction terms to the modified Friedmann equation of the FRW universe starting from the holographic principle and the Debye model.
ALTERNATIVE IMPLEMENTATION OF THE HIGGS BOSON
Authors: FOOT ROBERT , KOBAKHIDZE ARCHIL
Published: March 2011

We discuss an alternative implementation of the Higgs boson within the Standard Model which is possible if the renormalizability condition is relaxed. Namely, at energy scale Λ the Higgs boson interacts at tree-level only with matter fermions, while the full gauge invariance is still maintained. The interactions with the electroweak gauge bosons are induced at low energies through the radiative corrections. In this scenario the Higgs boson can be arbitrarily heavy, interacting with the Standard Model fields arbitrarily weakly. No violation of unitarity in the scattering of longitudinal electroweak bosons occurs, since they become unphysical degrees of freedom at energies Λ ~ TeV.