bluuebunny/crossref_metadata_2025 huggingface dataset:
Bending Behavior of Plain-Woven Fabric Air Beams: Fluid-Structure Interaction Approach
Authors: Cavallaro Paul V. , Sadegh Ali M. , Quigley Claudia J.
Published: April 2008

A swatch of plain-woven fabric was subjected to biaxial tests and its material characterization was performed. The stress-strain relations of the fabric were determined and directly used in finite element models of an air beam, assumed constructed with the same fabric, subjected to inflation and bending events. The structural responses to these events were obtained using the ABAQUS-Explicit[1] finite element solver for a range of pressures including those considered typical in safe operations of air inflated structures. The models accounted for the fluid-structure interactions between the air and the fabric. The air was treated as a compressible fluid in accordance with the Ideal Gas Law and was subjected to adiabatic constraints during bending. The fabric was represented with membrane elements and several constitutive cases including linear elasticity and hyperelasticity were studied. The bending behavior for each constitutive case is presented and discussions for their use and limitations follow.
Comparative Evaluation of the THOR-NT and Hybrid-III in Sled and Vehicle Tests
Authors: Ding Ke , Hassan Joseph , Nusholtz Guy
Published: April 2008

This paper compares the current THOR-NT and the Hybrid III in two different test series: The first series (series A) consisted of sled tests at 56 km per hour and a second series (series B) consisted of vehicle offset deformable barrier tests at 56 km per hour. Series A focused on comparing the repeatability of the impact response of the two dummies, in both full frontal and angled sled tests, for the head accelerations, thorax deflection and accelerations, pelvic accelerations, and neck loads. Series B focused on comparing the two dummies in a vehicle environment. The THOR dummy is considerably more complex than the Hybrid III and requires an increased workload in terms of handling and positioning, especially in a vehicle environment. With the limited data in this study, it was apparent that the THOR and Hybrid III have nominally the same level of repeatability. However, because of the increased instrumentation in the THOR, insights, in terms of impact response, can be obtained that cannot be obtained with the Hybrid III.
A Comparison Between Head Impact Response of Hybrid III and THOR-NT Dummy Heads in FMVSS201 Tests
Authors: Jaradat Waseem , Hassan Joseph , Nusholtz Guy , Taraman Khalil , Taraman Sanaa
Published: April 2008

The impact response of the forehead of both the Hybrid III dummy and THOR dummy was designed to the same human surrogate data. Therefore, when the forehead of either dummy is impacted with the same initial conditions, the acceleration response and consequently the head impact criterion HIC should be similar. If the THOR dummy is used in the FMVSS 201 free motion headform tests, then when it strikes the interior trim of the vehicle, as prescribed by the FMVSS 201 procedure, the acceleration response should be similar to that of the Hybrid III, as long as only the forehead engages the vehicle interior. To compare and contrast the response of the two dummy heads under FMVSS 201 testing, a design of experiments (DOE), that is a function of seven variables, is utilized to develop a mathematical model of the Head Impact Response. These independent parameters include five trim manufacturing process variables that relate to the interior that the dummy head hits in 201 testing: mold temperature, melt temperature, packing pressure, hold pressure, and injection speed. Two operational variables were also considered: free motion Headform approach angle and the dummy head drop calibration. An incomplete block design approach is utilized in order to significantly reduce the number of experiments. The DOE approach determines the response in the form of the Head Impact Criterion (HIC) with respect to the seven variables at 99% confidence level. The results describe the response data of both dummy heads. The response data of the dummy heads is described. Results indicate that the Hybrid III dummy head and the THOR dummy head have significantly different response characteristics in terms of magnitude of response, variation to different input conditions, repeatability, HIC values, and acceleration time history.
Development of New Spatio-Temporal Wind Exergy Maps
Authors: Sahin Ahmet Duran , Dincer Ibrahim , Rosen Marc A.
Published: April 2008

In this paper, energy and exergy characteristics of wind energy are investigated. The effects of wind speed and air temperature and pressure at the inlet of a wind turbine on wind chill temperature are examined. We also investigate energy and exergy efficiencies of the wind energy generating system and verify the models through a case study on a 100-kW wind generating system for 21 climatic stations in the province of Ontario, Canada. New energy and exergy efficiency maps of the wind energy generating system are introduced to provide a common basis for regional assessments and interpretations. These efficiency maps are plotted for two months of the year (January and July), which are taken to be representative months of the winter and summer seasons. The results show that aerial differences between energy and exergy efficiencies are approximately to 20-24% at low wind speeds and approximately to 10-15% at high wind speeds.
The Need for Spray and Aerosol Benchmark Databases
Authors: Presser C.
Published: April 2008

This paper describes a benchmark case suitable for validation of multiphase combustion models and submodels. The benchmark includes a reference spray combustor to provide well-defined input and boundary conditions, enabling measurements to characterize the fuel spray, combustion air, wall temperatures, exhaust gas temperatures and species concentrations. The characteristics (i.e., size, velocity, volume flux, etc.) of the methanol spray were determined using phase Doppler interferometry. Fourier-transform infrared spectroscopy was used to measure species concentrations in the reactor exhaust and the conversion of methanol. The inlet combustion air was characterized using particle image velocimetry and a five-hole pitot probe. The measurements constitute a database sufficiently complete for code validation; subsequently, several research groups have carried out simulations of the facility to varying degrees of success. This paper describes the salient features of the database, and some of the modeling issues and needs.
Influence of Primary and Secondary Flow Interaction on the Near Flow Field Mixing in an Enclosed Space
Authors: Khan Ijaz M. , Gilbert Tony , Barigou Mostafa
Published: April 2008

This paper presents the influence of an induction diffuser ports on a turbulent jet and its effect on the axial mean streamwise velocity decay, mass entrainment, turbulence characteristics and the temperature distribution in the near flow field of an enclosed numerical space. Convergence of the steady state simulations is achieved by RNG kappa-epsilon turbulence model. Comparisons of the axial mean streamwise velocity decay, turbulence characteristics and the temperature distribution in an enclosed space are reported for JETs (Jet Environmental Techniques) nozzle, and another similar simulation was conducted for an induction diffuser box with open ports at specific positions to evaluate its performance. The numerical analysis was validated by prototype experiments using the JETs nozzle geometry in a test room 11 m in length, 5.5 m wide and 2.5 m high. The measurement of the streamwise velocity and temperature distribution was measured inside the room on a grid with the help of a hotwire anemometer and digital thermometer, respectively. From the analysis of the data, it was found that the near flow field air entrainment and diffusion characteristics of the jet were significantly influenced by the air induction diffuser.
Oscillating Magnetic Field Effects on Convective Instability of Ferrofluids
Authors: Kaloni P. N.
Published: April 2008

Convective instability of a ferrofluid layer under gravity and a vertical time periodic magnetic field is investigated. Consideration, at the present, is given to quasistationary ferrohydrodynamic theory and influence of periodic magnetic force modulation on the convective stability is briefly discussed.
Energy Absorbability of Large Scale Inflatable Composite Structures
Authors: Quigley Claudia , Buehler Karen , Cavallaro Paul , Sadegh Ali
Published: April 2008

Airbeams, inflatable composite structures, have traditionally been used solely as structural elements. Modeling and test procedures have been under development by academia, industry and governmental agencies to predict and evaluate an airbeam's structural properties. However, the pneumatic component that gives airbeams their strength and stiffness also provides airbeams the capability to absorb energy. Test procedures and scaling laws that can be used to evaluate the energy absorbing capacity of these structural elements will be described and evaluated. Test data will show that airbeams can reliably absorb sufficient energy for applications such as a pneumatic fender and meet other functional requirements. The paper will also describe textile considerations and other material properties that will enable this application to be successful.
Thermoeconomic Costs of Production Analysis of a Diesel Cycle- Based Cogeneration Power Plant
Authors: Betancourth Jairo A. , Rangel Vi´ctor H. , Pacheco J. Jesu´s , Hernandez Abel , Rubio Jose´ C.
Published: April 2008

In this paper a thermoeconomic costs of production analysis of a diesel cycle-based cogeneration Honduran power plant is presented in order to obtain the total production cost of electricity and to obtain a costs allocation that is more rigorous, based on exergy concepts. These costs provide an idea of the measure of sacrifices of the utilized resources in order to generate the final product. Many papers related with thermoeconomic analysis can be cited. However, there are few articles related to this kind of analysis applied to a diesel cycle-based cogeneration power plant. Here, the Exergy Costs Theory has been applied in order to achieve the objectives. The power plant has 8 internal combustion engines with an 11.340 MW capacity each. Only three of them have a boiler installed which uses the exhaust gases of combustion for vapor generation. The others five emit the exhaust gases to the environment. Some options are explored to commercialize the residual steam since it is ejected still at high temperatures, either as direct sale or cogeneration for power production using micro turbines.
A Complete Computational Model of Ultrasound Vibro-Acoustography
Authors: Malcolm Alison E. , Reitich Fernando , Yang Jiaqi , Fatemi Mostafa , Greenleaf James F.
Published: April 2008

Ultrasound vibro-acoustography is a novel medical imaging modality that combines the high resolution of high-frequency ultrasound with the speckle-free images obtained using low-frequency methods. This imaging modality relies on the non-linear interaction of two high frequency beams at slightly different frequencies. We describe the physics of ultrasound vibro-acoustography and outline a strategy for its modeling, simulation, and optimal design.
Monte Carlo study of the dose rate distributions for the Ir2.A85‐2 and Ir2.A85‐1 Ir‐192 afterloading sources
Authors: Granero D. , Pérez‐Calatayud J. , Ballester F.
Published: April 2008

The two most commonly used modalities of cancer treatment in clinical brachytherapy practice today are high dose rate (HDR) and pulsed dose rate (PDR) brachytherapy. In a clinical treatment, quality dose rate distribution data sets of the brachytherapy sources are required for each source model. The purpose of this study is to obtain detailed dose rate distributions around the new BEBIG HDR and PDR Ir‐192 brachytherapy sources. These distributions will then be used as input data in the treatment planning systems dedicated to brachytherapy and its calculations can be verified. The Monte Carlo method was used to obtain the dose rate distributions around the sources studied, taking into account the AAPM‐ESTRO recent recommendations. A complete dosimetric data set for the BEBIG Ir‐192 HDR and PDR sources, types Ir2.A85‐2 and Ir2.A85‐1, were obtained. This dosimetric data set is composed of the TG‐43 dosimetric functions and parameters and along‐away dose rate table to facilitate quality control of treatment planning systems.
Threshold segmentation for PET target volume delineation in radiation treatment planning: The role of target‐to‐background ratio and target size
Authors: Brambilla M. , Matheoud R. , Secco C. , Loi G. , Krengli M. , Inglese E.
Published: April 2008

A multivariable approach was adopted to study the dependence of the percentage threshold used to define the boundaries of positive tissue on emission scan duration (ESD) and activity at the start of acquisition for different target sizes and target‐to‐background ratios. An anthropomorphic model, at least for counting rate characteristics, was used to study this dependence in conditions resembling the ones that can be encountered in the clinical studies. An annular ring of water bags of 3 cm thickness was fitted over an International Electrotechnical Commission (IEC) phantom in order to obtain counting rates similar to those found in average patients. The scatter fraction of the modified IEC phantom was similar to the mean scatter fraction measured on patients, with a similar scanner. A supplemental set of microhollow spheres was positioned inside the phantom. The NEMA NU 2‐2001 scatter phantom was positioned at the end of the IEC phantom to approximate the clinical situation of having activity that extends beyond the scanner field of view. The phantoms were filled with a solution of water and (12 kBq/mL) and the spheres with various ratios of 22.5, 10.3, and 3.6. Sequential imaging was performed to acquire PET images with varying background activity concentrations of about 12, 9, 6.4, 5.3, and 3.1 kBq/mL. The ESD was set to 60, 120, 180, and 240 s/bed. Data were fitted using two distinct multiple linear regression models for and . The fittings of both models were good with an of 0.86 in both cases. Neither ESD nor resulted as significant predictors of the . For the target size was the most significant predictor of the , followed by the ratio, while for the explanatory power of the target size and ratio were reversed, the ratio being now the most important predictor of the . Both the target size and ratio play a major role in explaining the variance of the , throughout the whole range of target sizes and ratios examined. Thus, algorithms aimed at automatic threshold segmentation should incorporate both variables with a relative weight which critically depends on target size.
Computer‐aided diagnosis of sonographic liver cirrhosis: A spleen‐reference approach
Authors: Yang Pei‐Ming , Chen Chung‐Ming , Lu Tung‐Wu , Yen Chih‐Pin
Published: April 2008

This article aimed to develop a computer‐aided diagnosis (CAD) algorithm for differential diagnosis of cirrhotic and noncirrhotic livers, allowing free adjustment of system settings to obtain the best scanned images. A spleen‐referenced approached was proposed. 505 pairs of images acquired from 322 subjects using three ultrasound imaging systems were evaluated. Each pair consisted of liver and spleen sonograms of the same subject. Medical doctors were free to adjust the system parameters to attain the best scanned images. Of these 322 subjects, 155 subjects were cirrhotic, and 167 subjects noncirrhotic. Four assessments were carried out to evaluate the effectiveness and robustness of the proposed algorithm on the variations of regions‐of‐interest, ultrasound imaging systems, and scanned images. Four feature pairs were proposed. A logistic regression function was used as the classifier. All performances were evaluated by the leave‐one‐out cross‐validation method. The proposed algorithm was compared with two previous CAD algorithms and all performance comparisons were based on paired‐sample tests. The mean values of the receiver operating characteristic curves and classification accuracies ranged as high as from 0.949 to 0.996 and from to , respectively, for the four assessments. At the family‐wise significance level, the proposed algorithm was shown to be superior to the two previous CAD algorithms and their modified versions in terms of the values.
Iterative reconstruction of a region of interest for transmission tomography
Authors: Ziegler Andy , Nielsen Tim , Grass Michael
Published: April 2008

It was shown that images reconstructed for transmission tomography with iterative maximum likelihood (ML) algorithms exhibit a higher signal‐to‐noise ratio than images reconstructed with filtered back‐projection type algorithms. However, a drawback of ML reconstruction in particular and iterative reconstruction in general is the requirement that the reconstructed field of view (FOV) has to cover the whole volume that contributes to the absorption. In the case of a high resolution reconstruction, this demands a huge number of voxels. This article shows how an iterative ML reconstruction can be limited to a region of interest (ROI) without losing the advantages of a ML reconstruction. Compared with a full FOV ML reconstruction, the reconstruction speed is mainly increased by reducing the number of voxels which are necessary for a ROI reconstruction. In addition, the speed of convergence is increased.
Monte Carlo calculations and experimental measurements of dosimetric parameters of the brachytherapy source
Authors: Sadeghi Mahdi , Raisali Gholamreza , Hosseini S. Hamed , Shavar Arzhang
Published: April 2008

This article presents a brachytherapy source having adsorbed onto a cylindrical silver rod that has been developed by the Agricultural, Medical, and Industrial Research School for permanent implant applications. Dosimetric characteristics (radial dose function, anisotropy function, and anisotropy factor) of this source were experimentally and theoretically determined in terms of the updated AAPM Task group 43 (TG‐43U1) recommendations. Monte Carlo simulations were used to calculate the dose rate constant. Measurements were performed using TLD‐GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. Precision machined bores in the phantom located the dosimeters and the source in a reproducible fixed geometry, providing for transverse‐axis and angular dose profiles over a range of distances from 0.5 to 5 cm. The Monte Carlo ‐particle (MCNP) code, version 4C simulation techniques have been used to evaluate the dose‐rate distributions around this model source in water and Perspex phantoms. The Monte Carlo calculated dose rate constant of the source in water was found to be with an approximate uncertainty of . The anisotropy function, , and the radial dose function, , of the source were also measured in a Perspex phantom and calculated in both Perspex and liquid water phantoms.
Monte Carlo simulation of backscatter from lead for clinical electron beams using EGSnrc
Authors: Chow James C. L. , Grigorov Grigor N.
Published: April 2008

In electron radiotherapy of superficial lesions in the eyelid, lip, buccal mucosa, ear, and nose, backscattered electrons are produced from the lead shield used to protect the critical tissue underneath the tumor. In this study, the backscattered electrons, produced by clinical electron beams using a Varian 21 EX linear accelerator, were studied using Monte Carlo simulations. The electron backscatter factor (EBF), defined as the ratio of dose at the tissue‐lead interface to the dose at the same point without the presence of backscatter, was calculated using the Monte Carlo EGSnrc‐based code. The calculated EBFs were verified with measurements using metal–oxide–semiconductor field effect transistor detectors. The effect of the (1) initial electron beam energy, (2) thickness of bolus over the lead shield, (3) beam's angle of incidence, and (4) presence of an aluminum sheet used to absorb backscattered electrons, on the EBF, were studied. It is found that for lead shielding positioned at any fixed depth, the EBF decreases with an increase in initial electron beam energy (4–16 MeV). In addition, for depths within the electron practical range, , and at a particular beam energy, the EBF increases with depth (or thickness of the treatment volume). When the electron beam angle increases from to , the EBF only decreases slightly for all energies. The influence of the beam obliquity on the EBF is important when the treatment surface is not flat and perpendicular to the central beam axis. The use of an aluminum sheet to reduce backscattered electrons was also investigated. For a relatively low electron beam energy (4 MeV), a 2 mm aluminum sheet can reduce backscattering by . While the electron beam energy increased, less backscattered electrons were produced and therefore removed by the same thickness of aluminum (only about for 16 MeV). The Monte Carlo calculated EBFs from this study, characterized by the electron beam energy, depth of bolus above the lead shield, beam obliquity, and presence of an aluminum sheet, may provide important clinical information for radiation oncology staff when considering the effect of electron backscatter on radiotherapy using internal shielding.
Unifying dose specification between clinical BNCT centers in the Americas
Authors: Riley K. J. , Binns P. J. , Harling O. K. , Kiger W. S. , González S. J. , Casal M. R. , Longhino J. , Larrieu O. A. Calzetta , Blaumann H. R.
Published: April 2008

A dosimetry intercomparison between the boron neutron capture therapy groups of the Massachusetts Institute of Technology (MIT) and the Comisión Nacional de Energía Atómica (CNEA), Argentina was performed to enable combined analyses of NCT patient data between the different centers. In‐air and dose versus depth measurements in a rectangular water phantom were performed at the hyperthermal neutron beam facility of the RA‐6 reactor, Bariloche. Calculated dose profiles from the CNEA treatment planning system NCTPlan that were calibrated against in‐house measurements required normalizations of 1.0 (thermal neutrons), 1.13 (photons), and 0.74 (fast neutrons) to match the dosimetry of MIT.
Automated detection of microcalcification clusters for digital breast tomosynthesis using projection data only: A preliminary study
Authors: Reiser I. , Nishikawa R. M. , Edwards A. V. , Kopans D. B. , Schmidt R. A. , Papaioannou J. , Moore R. H.
Published: April 2008

Digital breast tomosynthesis (DBT) is a promising modality for breast imaging in which an anisotropic volume image of the breast is obtained. We present an algorithm for computerized detection of microcalcification clusters (MCCs) for DBT. This algorithm operates on the projection views only. Therefore it does not depend on reconstruction, and is computationally efficient. The algorithm was developed using a database of 30 image sets with microcalcifications, and a control group of 30 image sets without visible findings. The patient data were acquired on the first DBT prototype at Massachusetts General Hospital. Algorithm sensitivity was estimated to be 0.86 at 1.3 false positive clusters, which is below that of current MCC detection algorithms for full‐field digital mammography. Because of the small number of patient cases, algorithm parameters were not optimized and one linear classifier was used. An actual limitation of our approach may be that the signal‐to‐noise ratio in the projection images is too low for microcalcification detection. Furthermore, the database consisted of predominantly small MCC. This may be related to the image quality obtained with this first prototype.
Comparison of fixed‐beam IMRT, helical tomotherapy, and IMPT for selected cases
Authors: Muzik Jan , Soukup Martin , Alber Markus
Published: April 2008

A growing number of advanced intensity modulated treatment techniques is becoming available. In this study, the specific strengths and weaknesses of four techniques, static and dynamic multileaf collimator (MLC), conventional linac‐based IMRT, helical tomotherapy (HT), and spot‐scanning proton therapy (IMPT) are investigated in the framework of biological, EUD–based dose optimization. All techniques were implemented in the same in‐house dose optimization tool. Monte Carlo dose computation was used in all cases. All dose‐limiting, normal tissue objectives were treated as hard constraints so as to facilitate comparability. Five patient cases were selected to offer each technique a chance to show its strengths: a deep‐seated prostate case (for linac‐based IMRT), a pediatric case (for IMPT), an extensive head–and‐neck case (for HT), a lung tumor (for HT), and an optical neurinoma (for noncoplanar linac‐based IMRT with a miniMLC). The plans were compared by dose statistics and equivalent uniform dose metrics. All techniques delivered results that were comparable with respect to target coverage and the most dose‐limiting normal tissues. Static MLC IMRT struggled to achieve sufficient target coverage at the same level of dose homogeneity in the lung case. IMPT gained the greatest advantage when lung sparing was important, but did not significantly reduce the risk of nearby organs. Tomotherapy and dynamic MLC IMRT showed mostly the same performance. Despite the apparent conceptual differences, all four techniques fare equally well for standard patient cases. The absence of relevant differences is in part due to biological optimization, which offers more freedom to shape the dose than do, e.g., dose volume histogram constraints. Each technique excels for certain classes of highly complex cases, and hence the various modalities should be viewed as complementary, rather than competing.
Stochasticity and Cell Fate
Authors: Losick Richard , Desplan Claude
Published: April 2008

Fundamental to living cells is the capacity to differentiate into subtypes with specialized attributes. Understanding the way cells acquire their fates is a major challenge in developmental biology. How cells adopt a particular fate is usually thought of as being deterministic, and in the large majority of cases it is. That is, cells acquire their fate by virtue of their lineage or their proximity to an inductive signal from another cell. In some cases, however, and in organisms ranging from bacteria to humans, cells choose one or another pathway of differentiation stochastically, without apparent regard to environment or history. Stochasticity has important mechanistic requirements. We speculate on why stochasticity is advantageous—and even critical in some circumstances—to the individual, the colony, or the species.
Single-Molecule DNA Sequencing of a Viral Genome
Authors: Harris Timothy D. , Buzby Phillip R. , Babcock Hazen , Beer Eric , Bowers Jayson , Braslavsky Ido , Causey Marie , Colonell Jennifer , DiMeo James , Efcavitch J. William , Giladi Eldar , Gill Jaime , Healy John , Jarosz Mirna , Lapen Dan , Moulton Keith , Quake Stephen R. , Steinmann Kathleen , Thayer Edward , Tyurina Anastasia , Ward Rebecca , Weiss Howard , Xie Zheng
Published: April 2008

The full promise of human genomics will be realized only when the genomes of thousands of individuals can be sequenced for comparative analysis. A reference sequence enables the use of short read length. We report an amplification-free method for determining the nucleotide sequence of more than 280,000 individual DNA molecules simultaneously. A DNA polymerase adds labeled nucleotides to surface-immobilized primer-template duplexes in stepwise fashion, and the asynchronous growth of individual DNA molecules was monitored by fluorescence imaging. Read lengths of >25 bases and equivalent phred software program quality scores approaching 30 were achieved. We used this method to sequence the M13 virus to an average depth of >150Ã and with 100% coverage; thus, we resequenced the M13 genome with high-sensitivity mutation detection. This demonstrates a strategy for high-throughput low-cost resequencing.
Reversible Compartmentalization of de Novo Purine Biosynthetic Complexes in Living Cells
Authors: An Songon , Kumar Ravindra , Sheets Erin D. , Benkovic Stephen J.
Published: April 2008

Purines are synthesized de novo in 10 chemical steps that are catalyzed by six enzymes in eukaryotes. Studies in vitro have provided little evidence of anticipated protein-protein interactions that would enable substrate channeling and regulation of the metabolic flux. We applied fluorescence microscopy to HeLa cells and discovered that all six enzymes colocalize to form clusters in the cellular cytoplasm. The association and dissociation of these enzyme clusters can be regulated dynamically, by either changing the purine levels of or adding exogenous agents to the culture media. Collectively, the data provide strong evidence for the formation of a multi-enzyme complex, the “purinosome,” to carry out de novo purine biosynthesis in cells.
Entrainment of Neuronal Oscillations as a Mechanism of Attentional Selection
Authors: Lakatos Peter , Karmos George , Mehta Ashesh D. , Ulbert Istvan , Schroeder Charles E.
Published: April 2008

Whereas gamma-band neuronal oscillations clearly appear integral to visual attention, the role of lower-frequency oscillations is still being debated. Mounting evidence indicates that a key functional property of these oscillations is the rhythmic shifting of excitability in local neuronal ensembles. Here, we show that when attended stimuli are in a rhythmic stream, delta-band oscillations in the primary visual cortex entrain to the rhythm of the stream, resulting in increased response gain for task-relevant events and decreased reaction times. Because of hierarchical cross-frequency coupling, delta phase also determines momentary power in higher-frequency activity. These instrumental functions of low-frequency oscillations support a conceptual framework that integrates numerous earlier findings.
Confronting Violence Face to Face
Authors: Laitin David D.
Published: April 2008

Violence
. A Micro-sociological Theory.
By Randall Collins
. Princeton University Press, Princeton, NJ, 2008. 579 pp. $45, £26.95. ISBN 9780691133133.

Examining photographic, video, forensic, and ethnographic evidence of a wide range of violent situations (from schoolyard bullying to armed conflict), the author argues that violence is not easily triggered and often injures unintended victims.
Serological Survey for Foot-and-Mouth Disease Virus in Wildlife in Eastern Africa and Estimation of Test Parameters of a Nonstructural Protein Enzyme-Linked Immunosorbent Assay for Buffalo
Authors: Bronsvoort B. M. D. C. , Parida S. , Handel I. , McFarland S. , Fleming L. , Hamblin P. , Kock R.
Published: April 2008

In this study we estimate the seroprevalence of foot-and-mouth disease virus (FMDV) in wildlife from eastern and central Africa. Sera were sourced from between 1994 and 2002 from a rinderpest surveillance program. Our study compared a nonstructural protein enzyme-linked immunosorbent assay (Cedi test) with a virus neutralization test. The study shows that there is only a low seroprevalence of FMDV in sampled nonbuffalo species. The seroprevalence in the Cape buffalo was high for SAT2, lower for SAT1, and lowest for SAT3. As the SAT2 serotype was most prevalent, the Cedi test largely reflected the occurrence of SAT2-positive animals. The results also suggest that SAT2 became dominant around 1998, with a large increase in seroprevalence. The sensitivity and specificity of the Cedi test were estimated by comparison to the combined virus neutralization test results from all three SAT tests. A Bayesian implementation of the Hui-Walter latent class model was used to estimate the test parameters. The model permits estimation in the absence of a gold standard test. The final model, using noninformative priors and assuming conditional independence of test performance, estimated Cedi test sensitivity at 87.7% and specificity at 87.3%. These estimates are similar to those for domestic bovines; they suggest that the Cedi test is a useful tool for screening buffalo for infection with the various serotypes of FMDV.
Catalase-Negative
Staphylococcus aureus
Strain with Point Mutations in the
katA
Gene
Authors: Piau C. , Jehan J. , Leclercq R. , Daurel C.
Published: April 2008

Methicillin-susceptible catalase-negative
Staphylococcus aureus
strain UCN61 was isolated from an arterial leg ulcer. The deduced sequence of the structural
katA
gene for the catalase was 99% identical to those of other
S. aureus
strains. Two mutations were identified in
katA
from
S. aureus
UCN61, including one leading to a substitution of key histidine 58 by a tyrosine.
Different Mutational Pathways to CXCR4 Coreceptor Switch of CCR5-Using Simian-Human Immunodeficiency Virus
Authors: Ho Siu-hong , Trunova Nataliya , Gettie Agegnehu , Blanchard James , Cheng-Mayer Cecilia
Published: April 2008

We report here a second case of coreceptor switch in R5 simian-human immunodeficiency virus SF162P3N (SHIV
SF162P3N
)-infected macaque CA28, supporting the use of this experimental system to examine factors that drive the change in coreceptor preference in vivo. Virus recovered from CA28 plasma (SHIV
CA28NP
) used both CCR5 and CXCR4 for entry, but the virus recovered from lymph node (SHIV
CA28NL
) used CXCR4 almost exclusively. Sequence and functional analyses showed that mutations in the V3 loop that conferred CXCR4 usage in macaque CA28 differed from those described in the previously reported case, demonstrating divergent mutational pathways for change in the coreceptor preference of the R5 SHIV
SF162P3N
isolate in vivo.
The Affinity of EBNA1 for Its Origin of DNA Synthesis Is a Determinant of the Origin's Replicative Efficiency
Authors: Lindner Scott E. , Zeller Krisztina , Schepers Aloys , Sugden Bill
Published: April 2008

Epstein-Barr virus (EBV) replicates its genome as a licensed plasmid in latently infected cells. Although replication of this plasmid is essential for EBV latent infection, its synthesis still fails for 16% of the templates in S phase. In order to understand these failures, we sought to determine whether the affinity of the initiator protein (EBNA1) for its binding sites in the origin affects the efficiency of plasmid replication. We have answered this question by using several engineered origins modeled upon the arrangement of EBNA1-binding sites found in DS, the major plasmid origin of EBV. The human TRF2 protein also binds to half-sites in DS and increases EBNA1's affinity for its own sites; we therefore also tested origin efficiency in the presence or absence of these sites. We have found that if TRF2-half-binding sites are present, the efficiency of supporting the initiation of DNA synthesis and of establishing a plasmid bearing that origin directly correlates with the affinity of EBNA1 for that origin. Moreover, the presence of TRF2-half-binding sites also increases the average level of EBNA1 and ORC2 bound to those origins in vivo, as measured by chromatin immunoprecipitation. Lastly, we have created an origin of DNA synthesis from high-affinity EBNA1-binding sites and TRF2-half-binding sites that functions severalfold more efficiently than does DS. This finding indicates that EBV has selected a submaximally efficient origin of DNA synthesis for the latent phase of its life cycle. This enhanced origin could be used practically in human gene vectors to improve their efficiency in therapy and basic research.
Recombinant Vesicular Stomatitis Virus Vector Mediates Postexposure Protection against Sudan Ebola Hemorrhagic Fever in Nonhuman Primates
Authors: Geisbert Thomas W. , Daddario-DiCaprio Kathleen M. , Williams Kinola J. N. , Geisbert Joan B. , Leung Anders , Feldmann Friederike , Hensley Lisa E. , Feldmann Heinz , Jones Steven M.
Published: April 2008

Recombinant vesicular stomatitis virus (VSV) vectors expressing homologous filoviral glycoproteins can completely protect rhesus monkeys against Marburg virus when administered after exposure and can partially protect macaques after challenge with
Zaire ebolavirus
. Here, we administered a VSV vector expressing the
Sudan ebolavirus
(SEBOV) glycoprotein to four rhesus macaques shortly after exposure to SEBOV. All four animals survived SEBOV challenge, while a control animal that received a nonspecific vector developed fulminant SEBOV hemorrhagic fever and succumbed. This is the first demonstration of complete postexposure protection against an Ebola virus in nonhuman primates and provides further evidence that postexposure vaccination may have utility in treating exposures to filoviruses.
Cyclophilin A Is an Essential Cofactor for Hepatitis C Virus Infection and the Principal Mediator of Cyclosporine Resistance In Vitro
Authors: Yang Feng , Robotham Jason M. , Nelson Heather B. , Irsigler Andre , Kenworthy Rachael , Tang Hengli
Published: April 2008

Cyclosporine (CsA) and its derivatives potently suppress hepatitis C virus (HCV) replication. Recently, CsA-resistant HCV replicons have been identified in vitro. We examined the dependence of the wild-type and CsA-resistant replicons on various cyclophilins for replication. A strong correlation between CsA resistance and reduced dependency on cyclophilin A (CyPA) for replication was identified. Silencing of CyPB or CyPC expression had no significant effect on replication, whereas various forms of small interfering RNA (siRNA) directed at CyPA inhibited HCV replication of wild-type but not CsA-resistant replicons. The efficiency of a particular siRNA in suppressing CyPA expression was correlated with its potency in inhibiting HCV replication, and expression of an siRNA-resistant CyPA cDNA rescued replication. In addition, an anti-CyPA antibody blocked replication of the wild-type but not the resistant replicon in an in vitro replication assay. Depletion of CyPA alone in the CsA-resistant replicon cells eliminated CsA resistance, indicating that CyPA is the chief mediator of the observed CsA resistance. The dependency on CyPA for replication was observed for both genotype (GT) 1a and 1b replicons as well as a GT 2a infectious virus. An interaction between CyPA and HCV RNA as well as the viral polymerase that is sensitive to CsA treatment in wild-type but not in resistant replicons was detected. These findings reveal the molecular mechanism of CsA resistance and identify CyPA as a critical cellular cofactor for HCV replication and infection.
Endoplasmic Reticulum Chaperones Are Involved in the Morphogenesis of Rotavirus Infectious Particles
Authors: Maruri-Avidal Liliana , López Susana , Arias Carlos F.
Published: April 2008

The final assembly of rotavirus particles takes place in the endoplasmic reticulum (ER). In this work, we evaluated by RNA interference the relevance to rotavirus assembly and infectivity of grp78, protein disulfide isomerase (PDI), grp94, calnexin, calreticulin, and ERp57, members of the two ER folding systems described herein. Silencing the expression of grp94 and Erp57 had no effect on rotavirus infectivity, while knocking down the expression of any of the other four chaperons caused a reduction in the yield of infectious virus of about 50%. In grp78-silenced cells, the maturation of the oligosaccharide chains of NSP4 was retarded. In cells with reduced levels of calnexin, the oxidative folding of VP7 was impaired and the trimming of NSP4 was accelerated, and in calreticulin-silenced cells, the formation of disulfide bonds of VP7 was also accelerated. The knockdown of PDI impaired the formation and/or rearrangement of the VP7 disulfide bonds. All these conditions also affected the correct assembly of virus particles, since compared with virions from control cells, they showed an altered susceptibility to EGTA and heat treatments, a decreased specific infectivity, and a diminished reactivity to VP7 with monoclonal antibody M60, which recognizes only this protein when its disulfide bonds have been correctly formed. In the case of grp78-silenced cells, the virus produced bound less efficiently to MA104 cells than virus obtained from control cells. All these results suggest that these chaperones are involved in the quality control of rotavirus morphogenesis. The complexity of the steps of rotavirus assembly that occur in the ER provide a useful model for studying the organization and operation of the complex network of chaperones involved in maintaining the quality control of this organelle.
Effects of petrissage massage on fatigue and exercise performance following intensive cycle pedalling
Authors: Ogai R , Yamane M , Matsumoto T , Kosaka M
Published: April 2008

Objective:

Petrissage is assumed to influence circulation as well as interstitial drainage of both superficial and deep tissues. To study its effect it was applied between consecutive bouts of supramaximal exercise performed by the lower leg muscles.

Methods:

Subjects were 11 healthy female students actively engaged in sports. Exercise bouts of ergometer cycling at loads determined individually (0.075 kp × body weight (kg)) for 5 s repeated eight times at intervals of 20 s had to be performed twice on an experimental day with 35 min intermittent bed rest. Each subject was investigated on two occasions with a minimum interval of 1 week, once without (control, CO) and once with 10 min petrissage (massage, MA) of the exercising lower leg during the bed rest phase. Effects of exercise bouts on blood lactate, muscle stiffness and perceived lower limb fatigue and their recovery before and after the second exercise bout were determined.

Results:

For the first exercise bouts total power did not differ between MA and CO. Courses of blood lactate did not differ between MA and CO. However, recovery from measured muscle stiffness (p<0.05) and perceived lower limb fatigue (p<0.05) were more pronounced and total power during the second exercise bout was enhanced (p<0.01) in MA as compared with CO subjects.

Conclusion:

Petrissage improved cycle ergometer pedalling performance independent of blood lactate but in correlation with improved recovery from muscle stiffness and perceived lower limb fatigue.
Examining the burden of work-related hospitalized injuries: definitional issues
Authors: Mitchell R , Williamson A
Published: April 2008

Background:

Identifying work-related injuries from hospitalization data is not straightforward. How a work-related injury, either acute or non-acute, is defined will affect injury enumeration, injury burden estimates, and subsequent priority setting for prevention activity.

Aim:

To examine the effect of different case identification criteria on the number and rate of hospitalized work-related injuries and to identify the type of pathologies that are recorded for work-related admissions that have an external cause code.

Method:

Identified work-related hospitalization admissions from 1 July 2000 to 30 June 2005 were analysed according to different injury case-selection criteria (ie, a principal diagnosis in the ICD-10-AM range S00–T98 and/or an external cause code in the ICD-10-AM range V01–Y98) and different admission restrictions (ie, exclusion of: transfers and type changes; re-admissions within 28 days; or day-only admissions). The principal diagnosis recorded for work-related admissions that had an external cause code were examined.

Results:

The incidence of identified work-related hospitalized injuries varied widely, from 289 to 611 per 100 000 workers depending on the identification criteria adopted. The exclusion of day-only stays reduced the identified work-related injury admissions by about one-third for each definitional condition. Where only an external cause code was used to identify an injury, the principal diagnoses codes were predominantly injuries, poisoning, and certain other consequences of external causes (74.6%) and diseases of the musculoskeletal system and connective tissue (15.5%).

Conclusions:

Case-selection criteria adopted to identify work-related hospitalized injuries should be carefully considered. It is recommended that inclusion of certain musculoskeletal conditions that are likely to arise from repetitive minor trauma over time (ie non-acute injuries) should be considered in calculating the estimate of the burden of all work-related hospitalized injuries.
Injury control: an opportunity for China
Authors: Hu G , Baker T D , Li G , Baker S P
Published: April 2008

Injury control is an important health issue in China, but has been less well explored than in other countries. To encourage health policy makers to give greater attention to injury control, this report highlights the great damage caused by injuries and the neglected status of injury control in China. China’s situation and the experiences and lessons from industrialized countries, especially the USA, are summarized. Finally, two opportunities to improve injury control in China are identified: establishment of a mechanism for multi-department coordination and collaboration; and improvement of injury data surveillance.
Spatial patterns in taiga plant communities following fire
Authors: Schaefer James A.
Published: April 2008

The scales of spatial patterns of the vascular understorey were examined during postfire succession in the taiga of southeastern Manitoba. Patterns of individual species from analogous burned (5 years old) and old-growth (≥ 90 years old) communities were revealed using Paired Quadrat Variance; multispecies patterns were determined with Moran's I following ordination. The scales of single-species patterns were variable within communities and not significantly different between the two age classes. Similarly, multispecies patterns displayed no consistent differences in scale according to age of the community. The results fail to support the hypothesis that the scale of the spatial pattern in plant communities increases with stand age. Key words: fire, taiga, spatial scale, succession.
Trichothecium roseum, a mycoparasite of Sclerotinia sclerotiorum
Authors: Huang H. C. , Kokko E. G.
Published: April 2008

Among sclerotia of Sclerotinia sclerotiorum collected from diseased bean plants in a field near Lethbridge in 1987 and 1988, 30 and 16%, respectively, were contaminated by Trichothecium roseum. Laboratory studies showed that T. roseum is a mycoparasite of S. sclerotiorum, able to infect and destroy sclerotia in dual cultures on potato dextrose agar. Among sclerotia inoculated with spores of T. roseum and incubated for 4 weeks on moist sand, 54 and 43% were infected and killed by the isolates TR-4 and TR-6, respectively. Transmission electron microscopic studies of infected sclerotia revealed that hyphae of T. roseum entered the rind tissue by penetrating the melanized cell walls or via junctions between cells. Lysis of host cell walls occurred at penetration sites. Hyphae of T. roseum ramified in cortical and medullary tissues, destroying the sclerotium. In sclerotia with light infections of T. roseum, numerous cortical and (or) medullary cells showed cytoplasmic granulation and vacuolization without direct association with the mycoparasitic hyphae. Key words: biocontrol, hyperparasite, mycoparasitism.