bluuebunny/crossref_metadata_2025 huggingface dataset:
Trace‐element concentrations in single circumstellar silicon carbide grains from the Murchison meteorite
Authors: Amari Sachiko , Hoppe Peter , Zinner Ernst , Lewis Roy S.
Published: June 2012

Abstract— Concentrations of the trace elements Mg, Al, Ca, Ti, V, Fe, Sr, Y, Zr, Ba and Ce were determined by ion microprobe mass spectrometry in 60 individual silicon carbide (SiC) grains (in addition, Nb and Nd were determined in 20 of them), from separate KJH (size range 3.4–5.9 μm) of the Murchison carbonaceous meteorite, whose C‐, N‐ and Si‐isotopic compositions have been measured before (Hoppe et al., 1994) and provide evidence that these grains are of stellar origin. The selected SiC grains represent all previously recognized subgroups: mainstream (20 < 12C/13C < 120; 200 < 14N/15N; Si isotopes on slope 1.34 line), grains A (12C/13C < 3.5), grains B (3.5 < 12C/13C < 10), grains X (15N excesses, large 28Si excesses) and grains Y (150 < 12C/13C < 260; Si isotopes on slope 0.35 line). Data on these grains are compared with measurements on fine‐grained SiC fractions. Trace‐element patterns reflect both the condensation behavior of individual elements and the source composition of the stellar atmospheres. A detailed discussion of the condensation of trace elements in SiC from C‐rich stellar atmospheres is given in a companion paper by Lodders and Fegley (1995). Elements such as Mg, Al, Ca, Fe and Sr are depleted because their compounds are more volatile than SiC. Elements whose compounds are believed to be more refractory than SiC can also be depleted due to condensation and removal prior to SiC condensation. Among the refractory elements, however, the heavy elements from Y to Ce (and Nd) are systematically enriched relative to Ti and V, indicating enrichments by up to a factor of 14 of the s‐process elements relative to elements lighter than Fe. Such enrichments are expected if N‐type carbon stars (thermally pulsing AGB stars) are the main source of circumstellar SiC grains. Large grains are less enriched than small grains, possibly because they are from different AGB stars. The trace‐element patterns of subgroups such as groups A and B and grains X can at least qualitatively be understood if grains A and B come from J‐type carbon stars (known to be lacking in s‐process enhancements shown by N‐type carbon stars) or carbon stars that had not experienced much dredge‐up of He‐shell material and if grains X come from supernovae. However, a remaining puzzle is how stars become carbon stars without much accompanying dredge‐up of s‐process elements.
Occurrence of noble metals in aluminum‐ and chromium‐ rich objects in ordinary chondrites and of baddeleyite (ZrO2) in a chromite inclusion
Authors: Michel‐Lévy M. Christophe , Robin E. , Blanc Ph.
Published: June 2012

Abstract— Platinum group elements (PGE) enrichments are found in Fe‐Ni blebs (<1 μm) in Al‐ and Cr‐rich objects in the ordinary chondrites Ste. Marguerite, Forest Vale, Montferré. In Ste. Marguerite, high ZrO2 concentrations (baddeleyite) are also present in a chromite inclusion. Iridium enrichment in this material compared to its metal content is confirmed by INAA. The widespread occurrence of PGE in Al‐ and Cr‐rich objects, mostly present in H‐group chondrites of nearly equilibrated types, must be taken into account to understand their conditions of formation.
Nonequilibrium solidification and microstructures of metal phases in the shock‐induced melt of the Yanzhuang (H6) chondrite
Authors: Ming Chen , Xiande Xie , Goresy A. El
Published: June 2012

Abstract— Dendrites in the metal‐troilite spherules in both shock‐induced melt veins and a melt pocket of the Yanzhuang chondrite show zoning in their microstructures. This feature is indicative of nonequilibrium solidification of the metal phases. Dendrites in the melt pocket have a typical crust‐core structure consisting of martensitic interiors (7.5–8.1 wt% Ni) and Ni‐rich rims (12.5–23.3 wt% Ni). In comparison, the dendrites in melt veins have three microstructural areas: (1) core (6.4–7.3 wt% Ni); (2) martensite between the core and rim (7.4–8.5 wt.% Ni); (3) Ni‐rich rim (12.8–21.4 wt% Ni). It is suggested that the difference in cooling rates following shock‐induced high temperature melting might be an important factor in producing the different dendritic microstructures in melt veins and melt pocket. Cooling rates deduced from measurements of secondary dendritic arm spacings are 100–400 °C/s in the melt veins and 6–30 °C/s in the melt pocket, respectively, and lie in the temperature interval 950 to 1400 °C.
Silica‐rich orthopyroxenite in the Bovedy chondrite
Authors: Ruzicka Alex , Kring David A. , Hill Dolores H. , Boynton William V. , Clayton Robert N. , Mayeda Toshiko K.
Published: June 2012

Abstract— A large (≥4.5 × 7 × 4 mm), igneous‐textured clast in the Bovedy (L3) chondrite is notable for its high bulk SiO2 content (57.5 wt%). The clast consists of normally zoned orthopyroxene (83.8 vol%), tridymite (6.2 %), an intergrowth of feldspar (5.8 %) and sodic glass (3.1 %), pigeonite (1.0 %), and small amounts of chromite (0.2 %), augite, and Fe, Ni‐metal; it is best described as a silica‐rich orthopyroxenite. The oxygen‐isotopic composition of the clast is similar, but not identical, to Bovedy and other ordinary chondrites. The clast has a superchondritic Si/Mg ratio, but has Mg/(Mg + Fe) and Fe/Mn ratios that are similar to ordinary chondrite silicate. The closest chemical analogues to the clast are radial‐pyroxene chondrules, diogenites, pyroxene‐silica objects in ordinary chondrites, and silicates in the IIE iron meteorite Weekeroo Station.

The clast crystallized from a siliceous melt that cooled fast enough to prevent complete attainment of equilibrium but slow enough to allow nearly complete crystallization. The texture, form, size and composition of the clast suggest that it is an igneous differentiate from an asteroid or planetesimal that formed in the vicinity of ordinary chondrites. The melt probably cooled in the near‐surface region of the parent object. It appears that in the source region of the clast, metallic and silicate partial melt were largely‐to‐completely lost during a relatively low degree of melting, and that during a higher degree of melting, olivine and low‐Ca pyroxene separated from the remaining liquid, which ultimately solidified to form the clast. While these fractionation steps could not have all occurred at the same temperature, they could have been accomplished in a single melting episode, possibly as a result of heating by radionuclides or by electromagnetic induction. Fractionated magmas can also account for other Si‐rich objects in chondrites.
Investigating the implicit theories of rape‐prone men using an interpretative bias task
Authors: Blake Emily , Gannon Theresa A.
Published: June 2012

Purpose. Ward (2000) has hypothesized that sexual offenders hold offence supportive implicit theories (ITs) or schemata that function to facilitate or maintain offending behaviour. The present research aimed to determine whether rape‐prone men hold the same offence supportive ITs as those that have been identified in rapists.

Method. This study adopted both an explicit measure of ITs and also an implicit measure of ITs (an interpretative bias task). In the implicit task, participants viewed ambiguous stimuli (one‐sentence statements) that may be interpreted in either a rape‐supportive manner, or a non‐rape‐supportive manner. Participant's interpretation of the stimuli was assessed via a memory recognition task. We predicted that men higher on proclivity to rape – who presumably hold strong mental representations of rape‐supportive themes – would be more likely to interpret stimuli in a rape‐supportive manner relative to non‐rape‐supportive stimuli compared to men lower on rape proclivity.

Results. Using multiple regression to determine the relative contributions of both explicit and implicit measures for predicting rape proclivity, we found that only the explicit, self‐report questionnaire and one of the ITs, ‘women are sex objects’ (as measured by the interpretative bias task), was significantly related to a person's rape proclivity score.

Conclusions. This result indicates that rape‐prone men may not share the same beliefs as convicted rapists, which could be a key difference between men at risk of offending, and those who have been convicted of a sexual offence.
Selective Self-Excitation of Higher Vibrational Modes of Graphene Nano-Ribbons and Carbon Nanotubes Through Magnetomotive Instability
Authors: Nordenfelt A.
Published: June 2012

We demonstrate theoretically the feasibility of selective self-excitation of higher-mode flexural vibrations of graphene nano-ribbons and carbon nanotubes by the means of magnetomotive instability. Apart from the mechanical resonator, the device consists only of a constant voltage source, an inductor, a capacitor, a gate electrode, and a constant magnetic field. Numerical simulations were performed on both graphene and carbon nanotubes displaying an overall similar behavior, but with some differences arising mainly due to the nonlinear forces caused by the mechanical deformation. The advantages and disadvantages of both materials are discussed.
Measurements of Lateral Impedance and Local Characteristics of Solid Oxide Fuel Cells
Authors: Cheng Shih-Wei , Shui Yaw-Hwa , Cheng Yung-Neng , Lee Ruey-Yi
Published: June 2012

Lateral impedance and local characteristics of anode-supported solid oxide fuel cells (SOFCs) are studied in this paper. The testing device, which combines the original cell housing with a four-point probe equipment, is set for measuring SOFC single cell. The current collectors on anode and cathode in the original cell housing are, respectively, replaced by four independent probe units. They are not only to collect current, but also become measuring probes. Therefore, the lateral impedance of anode and cathode can be measured. Furthermore, the local characteristics are examined by open circuit voltage (OCV), I-V curve, and electrochemical impedance spectroscopy (EIS) measurements. The results show that the lateral impedance is substantially varied with temperature, the OCV at the center of the cell are higher than the edge, the central location on cell have better performance and lower impedance than the marginal location.
The role of time and place cues in the detection of frequency modulation by hearing-impaired listeners
Authors: Ernst Stephan M. A. , Moore Brian C. J.
Published: June 2012

Frequency modulation detection limens (FMDLs) were measured for five hearing-impaired (HI) subjects for carrier frequencies fc = 1000, 4000, and 6000 Hz, using modulation frequencies fm = 2 and 10 Hz and levels of 20 dB sensation level and 90 dB SPL. FMDLs were smaller for fm = 10 than for fm = 2 Hz for the two higher fc, but not for fc = 1000 Hz. FMDLs were also determined with additional random amplitude modulation (AM), to disrupt excitation-pattern cues. The disruptive effect was larger for fm = 10 than for fm = 2 Hz. The smallest disruption occurred for fm = 2 Hz and fc = 1000 Hz. AM detection thresholds for normal-hearing and HI subjects were measured for the same fc and fm values. Performance was better for the HI subjects for both fm. AM detection was much better for fm = 10 than for fm = 2 Hz. Additional tests showed that most HI subjects could discriminate temporal fine structure (TFS) at 800 Hz. The results are consistent with the idea that, for fm = 2 Hz and fc = 1000 Hz, frequency modulation (FM) detection was partly based on the use of TFS information. For higher carrier frequencies and for all carrier frequencies with fm = 10 Hz, FM detection was probably based on place cues.
Acoustical and mechanical characterization of poroelastic materials using a Bayesian approach
Authors: Chazot Jean-Daniel , Zhang Erliang , Antoni Jérôme
Published: June 2012

A characterization method of poroelastic materials saturated by air is described. This inverse method enables the evaluation of all the parameters with a simple measurement in a standing wave tube. Moreover, a Bayesian approach is used to return probabilistic data such as the maximum a posteriori and the confidence interval of each parameter. To get these data, it is necessary to define prior probability distributions on the parameters characterizing the studied material. This last point is very important to regularize the inverse problem of identification. In a first step, the direct problem formulation is presented. Then, the inverse characterization is developed and applied to simulated and experimental data.
Application of small-roughness perturbation theory to reverberation in range-dependent waveguides
Authors: Tang Dajun , Jackson Darrell R.
Published: June 2012

A rough-interface reverberation model is developed for range-dependent environments. First-order perturbation theory is employed, and the unperturbed background medium can be layered and heterogeneous with arbitrary range dependence. To calculate the reverberation field, two-way forward scatter due to the slowly changing unperturbed environment is handled by fast numerical methods. Backscatter due to small roughness superimposed on any of the slowly varying interfaces is handled efficiently using a Monte Carlo approach. Numerical examples are presented to demonstrate the application of the model. The primary purpose of the model is to incorporate relevant physics while improving computational speed.
Air-coupled ultrasonic investigation of stacked cylindrical rods
Authors: Liu Jingfei , Declercq Nico F.
Published: June 2012

Measurement of the periodicities of diffraction gratings composed of stacked cylindrical rods is explored using an air-coupled ultrasonic technique. Acoustic Bragg scattering from three periodic structures is investigated by means of a polar scan. Consequently, Bragg angles and corresponding frequencies are obtained from angular spectrograms, using two different data acquisition approaches. According to the principle of Bragg scattering, the periodicities of the three periodic structures, which are equal to the diameter of the cylindrical rods, are determined. In order to evaluate the reliability of the technique and its accuracy, the obtained diameters are compared with those directly measured with a digital caliber. To show the robustness of the technique measurements are done with transducers of different quality.
Investigating the wave-fixed and place-fixed origins of the 2f1-f2 distortion product otoacoustic emission within a micromechanical cochlear model
Authors: Young Jacqueline A. , Elliott Stephen J. , Lineton Ben
Published: June 2012

The 2f1-f2 distortion product otoacoustic emission (DPOAE) arises within the cochlea due to the nonlinear interaction of two stimulus tones (f1 and f2). It is thought to comprise contributions from a wave-fixed source and a place-fixed source. The generation and transmission of the 2f1-f2 DPOAE is investigated here using quasilinear solutions to an elemental model of the human cochlea with nonlinear micromechanics. The micromechanical parameters and nonlinearity are formulated to match the measured response of the cochlea to single- and two-tone stimulation. The controlled introduction of roughness into the active micromechanics of the model allows the wave- and place-fixed contributions to the DPOAE to be studied separately. It is also possible to manipulate the types of nonlinear suppression that occur within the quasilinear model to investigate the influence of stimulus parameters on DPOAE generation. The model predicts and explains a variety of 2f1-f2 DPOAE phenomena: The dependence of emission amplitude on stimulus parameters, the weakness of experiments designed to quantify cochlear amplifier gain, and the predominant mechanism which gives rise to DPOAE fine structure. In addition, the model is used to investigate the properties of the wave-fixed source and how these properties are influenced by the stimulus parameters.
Nonlinear elastic imaging using reciprocal time reversal and third order symmetry analysis
Authors: Ciampa Francesco , Meo Michele
Published: June 2012

This paper presents a nonlinear imaging method for the detection of the nonlinear signature due to impact damage in complex anisotropic solids with diffuse field conditions. The proposed technique, based on a combination of an inverse filtering approach with phase symmetry analysis and frequency modulated excitation signals, is applied to a number of waveforms containing the nonlinear impulse responses of the medium. Phase symmetry analysis was used to characterize the third order nonlinearity of the structure by exploiting its invariant properties with the phase angle of the input waveforms. Then, a “virtual” reciprocal time reversal imaging process, using only one broadcasting transducer and one receiving transducer, was used to insonify the defect taking advantage of multiple linear scattering as mode conversion and boundary reflections. The robustness of this technique was experimentally demonstrated on a damaged sandwich panel, and the nonlinear source, induced by low-velocity impact loading, was retrieved with a high level of accuracy. Its minimal processing requirements make this method a valid alternative to the traditional nonlinear elastic wave spectroscopy techniques for materials showing either classical or non-classical nonlinear behavior.
Estimating the parameters of audible clinical percussion signals by fitting exponentially damped harmonics
Authors: Bhuiyan Moinuddin , Malyarenko Eugene V. , Pantea Mircea A. , Maev Roman Gr. , Baylor Alfred E.
Published: June 2012

Used for centuries in the clinical practice, audible percussion is a method of eliciting sounds by tapping various areas of the human body either by finger tips or by a percussion hammer. Despite its advantages, pulmonary diagnostics by percussion is still highly subjective, depends on the physician’s skills, and requires quiet surroundings. Automation of this well-established technique could help amplify its existing merits while removing the above drawbacks. In this work, clinical percussion signals from normal volunteers are decomposed into a sum of exponentially damped sinusoids (EDS) whose parameters are determined using the Matrix Pencil Method. Some EDS represent transient oscillation modes of the thorax/abdomen excited by the percussion event, while others are associated with the noise. It is demonstrated that relatively few EDS are usually enough to accurately reconstruct the original signal. It is shown that combining the frequency and damping parameters of these most significant EDS allows for efficient classification of percussion signals into the two main types historically known as “resonant” and “tympanic.” This classification ability can provide a basis for the automated objective diagnostics of various pulmonary pathologies including pneumothorax. The algorithm can be implemented on an embedded platform for the battlefield and other emergency applications.
Waveguide characteristics of coupled in-plane waves
Authors: Pan Jie , Lu Jing , Qiu Xiaojun
Published: June 2012

In-plane waves in a waveguide made from a thin plate are described by a superposition of a set of orthogonal functions that satisfy the edge conditions of the waveguide. Due to the Poisson and shear effects, the displacement components of the in-plane waves along the two in-plane orthogonal coordinates are coupled and this coupling affects the propagation and spatial properties of the waveguide modes. The orthogonal functions and their associated wavenumbers represent the characteristics of the uncoupled modes of the waveguide where the above mentioned couplings are ignored. This study demonstrates that the characteristics of the waveguide modes are determined by the couplings of the uncoupled mode pairs, which become significant when the pairs satisfy the conditions of spatial coincidence. At some frequencies, certain waveguide modes can be determined by a single pair of uncoupled modes. For this case, the analytical solution for the waveguide modes exists and provides both a qualitative and quantitative interpretation of the characteristics of the waveguide mode.
Sound field control with a circular double-layer array of loudspeakers
Authors: Chang Ji-Ho , Jacobsen Finn
Published: June 2012

This paper describes a method of generating a controlled sound field for listeners inside a circular array of loudspeakers without disturbing people outside the array appreciably. To achieve this objective, a double-layer array of loudspeakers is used. Several solution methods are suggested, and their performance is examined using computer simulations. Two performance indices are used in this work, (a) the level difference between the average sound energy density in the listening zone and that in the quiet zone (sometimes called “the acoustic contrast”), and (b) a normalized measure of the deviations between the desired and the generated sound field in the listening zone. It is concluded that the best compromise is obtained with a method that combines pure contrast maximization with a pressure matching technique.
Efficient computation of the sound fields above a layered porous ground
Authors: Liu Sheng , Li Kai Ming
Published: June 2012

An efficient computation of sound fields due to a monopole source placed above a porous layer is presented. This paper examines an improved scheme whereby the steepest descent path is selected for the numerical evaluation of the Sommerfeld integral. Along the steepest descent path, a standard Gaussian-Hermite quadrature can be used to calculate the sound fields effectively. The suggested numerical scheme is accurate at all frequencies except in the very near field. The proposed method is more numerically efficient than other computational schemes, especially at long ranges and high source frequencies.
Probabilistic solution of some multi-degree-of-freedom nonlinear systems under external independent Poisson white noises
Authors: Zhu H. T.
Published: June 2012

This paper studies the stationary probability density function (PDF) of the response of multi-degree-of-freedom nonlinear systems under external independent Poisson white noises. The PDF is governed by the high-dimensional generalized Fokker–Planck–Kolmogorov (FPK) equation. The state-space-split (3S) method is adopted to reduce the high-dimensional generalized FPK equation to a low-dimensional equation. Subsequently, the exponential-polynomial closure (EPC) method is further used to solve the reduced FPK equation for the PDF solution. Two illustrative examples are presented to examine the accuracy of the 3S-EPC solution procedure. One example involves a two-degree-of-freedom coupled nonlinear system. The other example is concerned with a ten-degree-of-freedom system with cubic terms in displacement. A Monte Carlo simulation is also performed for simulating the PDF solution of the response. The comparison with the simulated result shows that the 3S-EPC solution procedure can provide satisfactory PDF solutions. The good agreement is also observed in the tail regions of the PDF solutions.
Fast simulation of second harmonic ultrasound field using a quasi-linear method
Authors: Prieur Fabrice , Johansen Tonni Franke , Holm Sverre , Torp Hans
Published: June 2012

Nonlinear propagation of sound has been exploited in the last 15 years in medical ultrasound imaging through tissue harmonic imaging (THI). THI creates an image by filtering the received ultrasound echo around the second harmonic frequency band. This technique produces images of enhanced quality due to reduced body wall reverberation, lower perturbations from off-axis echoes, and multiple scattering of reduced amplitude. In order to optimize the image quality it is essential to be able to predict the amplitude level and spatial distribution of the propagating ultrasound pulse. A method based on the quasi-linear approximation has been developed to quickly provide an estimate of the ultrasound pulse. This method does not need to propagate the pulse stepwise from the source plane to the desired depth; it directly computes a transverse profile at any depth from the definitions of the transducer and the pulse. The computation handles three spatial dimensions which allows for any transducer geometry. A comparison of pulse forms, transverse profiles, as well as axial profiles obtained by this method and state-of-the-art simulators, the KZKTexas code, and Abersim, shows a satisfactory match. The computation time for the quasi-linear method is also smaller than the time required by the other methods.
Sparse Pre-Columbian Human Habitation in Western Amazonia
Authors: McMichael C. H. , Piperno D. R. , Bush M. B. , Silman M. R. , Zimmerman A. R. , Raczka M. F. , Lobato L. C.
Published: June 2012

Population Limits

Extensive pre-Columbian populations inhabited the central and eastern Amazon basin, as evidenced by the clearing and modification of forests.

McMichael
et al.

(p.
1429
) examined how far inland such activities may have extended by sampling soils across western Amazonia, including river bluffs, which were heavily occupied downstream. Little evidence of human disturbance across a wide region was found by looking for charcoal layers (which would suggest use of fire) and phytoliths, which trace local plants and would indicate the presence of crops. Furthermore, no ceramics or tools were found. Thus, pre-Columbian human populations seem to have been sparse in western Amazonia.
The Urban Challenge
Authors: Fisk David
Published: June 2012

Cities race to reconfigure, to extract the most from waste matter and energy, and minimize the overhead of transport.
Science for Sustainable Development
Authors: Wible Brad
Published: June 2012

The Rio+20 United Nations Conference on Sustainable Development provides an opportunity for experts to reflect on progress, challenges, opportunities, and the role of science.
Harnessing New Scientific Capacity
Authors: Abreu Alice
Published: June 2012

Robust technical capacity in developing countries must be cultivated and integrated into research and policy-making.
COX-2 Inhibitors and Cardiovascular Risk
Authors: Cannon Christopher P. , Cannon Paul J.
Published: June 2012

The vascular location of an enzyme accounts for the cardiovascular hazards associated with its inhibition.
Role of Signal-to-Cutoff Ratios in Hepatitis C Virus Antibody Detection
Authors: Moretti Marco , Pieretti Barbara , Masucci Annamaria , Sisti Davide , Rocchi Marco , Delprete Ernesto
Published: June 2012

We reviewed results from 12,800 samples tested for hepatitis C virus (HCV) antibody detection in our laboratory by screening (Ortho chemiluminescence immunoassay [CIA]) and supplemental tests (Chiron recombinant immunoblot assay [RIBA]). We found that a signal-to-cutoff (S/Co) ratio of 10.3 was, in our setting, the most efficient cutoff point to improve the diagnostic algorithm of HCV infection.
Recombinant Protective Antigen Anthrax Vaccine Improves Survival when Administered as a Postexposure Prophylaxis Countermeasure with Antibiotic in the New Zealand White Rabbit Model of Inhalation Anthrax
Authors: Leffel Elizabeth K. , Bourdage James S. , Williamson E. Diane , Duchars Matthew , Fuerst Thomas R. , Fusco Peter C.
Published: June 2012

Inhalation anthrax is a potentially lethal form of disease resulting from exposure to aerosolizedBacillus anthracisspores. Over the last decade, incidents spanning from the deliberate mailing ofB. anthracisspores to incidental exposures in users of illegal drugs have highlighted the importance of developing new medical countermeasures to protect people who have been exposed to “anthrax spores” and are at risk of developing disease. The New Zealand White rabbit (NZWR) is a well-characterized model that has a pathogenesis and clinical presentation similar to those seen in humans. This article reports how the NZWR model was adapted to evaluate postexposure prophylaxis using a recombinant protective antigen (rPA) vaccine in combination with an oral antibiotic, levofloxacin. NZWRs were exposed to multiples of the 50% lethal dose (LD50) ofB. anthracisspores and then vaccinated immediately (day 0) and again on day 7 postexposure. Levofloxacin was administered daily beginning at 6 to 12 h postexposure for 7 treatments. Rabbits were evaluated for clinical signs of disease, fever, bacteremia, immune response, and survival. A robust immune response (IgG anti-rPA and toxin-neutralizing antibodies) was observed in all vaccinated groups on days 10 to 12. Levofloxacin plus either 30 or 100 μg rPA vaccine resulted in a 100% survival rate (18 of 18 per group), and a vaccine dose as low as 10 μg rPA resulted in an 89% survival rate (16 of 18) when used in combination with levofloxacin. In NZWRs that received antibiotic alone, the survival rate was 56% (10 of 18). There was no adverse effect on the development of a specific IgG response to rPA in unchallenged NZWRs that received the combination treatment of vaccine plus antibiotic. This study demonstrated that an accelerated two-dose regimen of rPA vaccine coadministered on days 0 and 7 with 7 days of levofloxacin therapy results in a significantly greater survival rate than with antibiotic treatment alone. Combination of vaccine administration and antibiotic treatment may be an effective strategy for treating a population exposed to aerosolizedB. anthracisspores.
Differential Interleukin-10 (IL-10) and IL-23 Production by Human Blood Monocytes and Dendritic Cells in Response to Commensal Enteric Bacteria
Authors: Manuzak Jennifer , Dillon Stephanie , Wilson Cara
Published: June 2012

Human peripheral blood contains antigen-presenting cells (APC), including dendritic cells (DC) and monocytes, that may encounter microbes that have translocated from the intestine to the periphery in disease states like HIV-1 infection and inflammatory bowel disease. We investigated the response of DC and monocytes in peripheral blood mononuclear cells (PBMC) to a panel of representative commensal enteric bacteria, includingEscherichia coli,Enterococcussp., andBacteroides fragilis. All three bacteria induced significant upregulation of the maturation and activation markers CD40 and CD83 on myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC). However, only mDC produced cytokines, including interleukin-10 (IL-10), IL-12p40/70, and tumor necrosis factor alpha (TNF-α), in response to bacterial stimulation. Cytokine profiles in whole PBMC differed depending on the stimulating bacterial species:B. fragilisinduced production of IL-23, IL-12p70, and IL-10, whereasE. coliandEnterococcusinduced an IL-10-predominant response. mDC and monocyte depletion experiments indicated that these cell types differentially produced IL-10 and IL-23 in response toE. coliandB. fragilis. Bacteroides thetaiotaomicrondid not induce levels of IL-23 similar to those ofB. fragilis, suggesting thatB. fragilismay have unique proinflammatory properties amongBacteroidesspecies. The addition of recombinant human IL-10 to PBMC cultures stimulated with commensal bacteria abrogated the IL-23 response, whereas blocking IL-10 significantly enhanced IL-23 production, suggesting that IL-10 controls the levels of IL-23 produced. These results indicate that blood mDC and monocytes respond differentially to innate stimulation with whole commensal bacteria and that IL-10 may play a role in controlling the proinflammatory response to translocated microbes.
Lethal Monkeypox Virus Infection of CAST/EiJ Mice Is Associated with a Deficient Gamma Interferon Response
Authors: Earl Patricia L. , Americo Jeffrey L. , Moss Bernard
Published: June 2012

Monkeypox virus (MPXV) is endemic in Africa, where it causes disease in humans resembling smallpox. A recent importation of MPXV-infected animals into the United States raises the possibility of global spread. Rodents comprise the major reservoir of MPXV, and a variety of such animals, even those native to North America, are susceptible. In contrast, common inbred strains of mice, including BALB/c and C57BL/6, are greatly resistant to MPXV. However, several inbred strains of mice derived from wild mice, including CAST/EiJ, exhibit morbidity and mortality at relatively low inoculums of MPXV. Elucidating the basis for the susceptibility of CAST/EiJ mice could contribute to an understanding of MPXV pathogenicity and host defense mechanisms and enhance the value of this mouse strain as a model system for evaluation of therapeutics and vaccines. Here we compared virus dissemination and induced cytokine production in CAST/EiJ mice to those in the resistant BALB/c strain. Following intranasal infection, robust virus replication occurred in the lungs of both strains, although a relatively higher inoculum was required for BALB/c. However, while spread to other internal organs was rapid and efficient in CAST/EiJ mice, the virus was largely restricted to the lungs in BALB/c mice. Gamma interferon (IFN-γ) and CCL5 were induced in lungs of BALB/c mice concomitant with virus replication but not in CAST/EiJ mice. The importance of IFN-γ in protection against MPXV disease was demonstrated by the intranasal administration of the mouse cytokine to CAST/EiJ mice and the resulting protection against MPXV. Furthermore, C57BL/6 mice with inactivation of the IFN-γ gene or the IFN-γ receptor gene exhibited enhanced sensitivity to MPXV.
Impact of VP1-Specific Protein Sequence Motifs on Adeno-Associated Virus Type 2 Intracellular Trafficking and Nuclear Entry
Authors: Popa-Wagner Ruth , Porwal Manvi , Kann Michael , Reuss Matthias , Weimer Marc , Florin Luise , Kleinschmidt Jürgen A.
Published: June 2012

Adeno-associated virus type 2 (AAV2) has gained much interest as a gene delivery vector. A hallmark of AAV2-mediated gene transfer is an intracellular conformational change of the virus capsid, leading to the exposure of infection-relevant protein domains. These protein domains, which are located on the N-terminal portion of the structural proteins VP1 and VP2, include a catalytic phospholipase A
2
domain and three clusters of basic amino acids. We have identified additional protein sequence motifs located on the VP1/2 N terminus that also proved to be obligatory for virus infectivity. These motifs include signals that are known to be involved in protein interaction, endosomal sorting and signal transduction in eukaryotic cells. Among different AAV serotypes they are highly conserved and mutation of critical amino acids of the respective motifs led to a severe infection-deficient phenotype. In particular, mutation of a YXXQ-sequence motif significantly reduced accumulation of virus capsids around the nucleus in comparison to wild-type AAV2. Interestingly, intracellular trafficking of AAV2 was shown to be independent of PLA
2
activity. Moreover, mutation of three PDZ-binding motifs, which are located consecutively at the very tip of the VP1 N terminus, revealed a nuclear transport-defective phenotype, suggesting a role in nuclear uptake of the virus through an as-yet-unknown mechanism.
Ovine TRIM5α Can Restrict Visna/Maedi Virus
Authors: Jáuregui P. , Crespo H. , Glaria I. , Luján L. , Contreras A. , Rosati S. , de Andrés D. , Amorena B. , Towers G. J. , Reina R.
Published: June 2012

The restrictive properties of tripartite motif-containing 5 alpha (TRIM5α) from small ruminant species have not been explored. Here, we identify highly similar TRIM5α sequences in sheep and goats. Cells transduced with ovine TRIM5α effectively restricted the lentivirus visna/maedi virus DNA synthesis. Proteasome inhibition in cells transduced with ovine TRIM5α restored restricted viral DNA synthesis, suggesting a conserved mechanism of restriction. Identification of TRIM5α active molecular species may open new prophylactic strategies against lentiviral infections.
Kaposi's Sarcoma-Associated Herpesvirus G-Protein-Coupled Receptor Prevents AU-Rich-Element-Mediated mRNA Decay
Authors: Corcoran Jennifer A. , Khaperskyy Denys A. , Johnston Benjamin P. , King Christine A. , Cyr David P. , Olsthoorn Alisha V. , McCormick Craig
Published: June 2012

During lytic Kaposi's sarcoma-associated herpesvirus (KSHV) infection, host gene expression is severely restricted by a process of global mRNA degradation known as host shutoff, which rededicates translational machinery to the expression of viral proteins. A subset of host mRNAs is spared from shutoff, and a number of these contain
cis
-acting AU-rich elements (AREs) in their 3′ untranslated regions. AREs are found in labile mRNAs encoding cytokines, growth factors, and proto-oncogenes. Activation of the p38/MK2 signal transduction pathway reverses constitutive decay of ARE-mRNAs, resulting in increased protein production. The viral G-protein-coupled receptor (vGPCR) is thought to play an important role in promoting the secretion of angiogenic molecules from KSHV-infected cells during lytic replication, but to date it has not been clear how vGPCR circumvents host shutoff. Here, we demonstrate that vGPCR activates the p38/MK2 pathway and stabilizes ARE-mRNAs, augmenting the levels of their protein products. Using MK2-deficient cells, we demonstrate that MK2 is essential for maximal vGPCR-mediated ARE-mRNA stabilization. ARE-mRNAs are normally delivered to cytoplasmic ribonucleoprotein granules known as processing bodies (PBs) for translational silencing and decay. We demonstrate that PB formation is prevented during KSHV lytic replication or in response to vGPCR-mediated activation of RhoA subfamily GTPases. Together, these data show for the first time that vGPCR impacts gene expression at the posttranscriptional level, coordinating an attack on the host mRNA degradation machinery. By suppressing ARE-mRNA turnover, vGPCR may facilitate escape of certain target mRNAs from host shutoff and allow secretion of angiogenic factors from lytically infected cells.
Suboptimal Provirus Expression Explains Apparent Nonrandom Cell Coinfection with HIV-1
Authors: Brégnard Christelle , Pacini Gregory , Danos Olivier , Basmaciogullari Stéphane
Published: June 2012

Despite the ability of primate lentiviruses to prevent infected cells from being reinfected, cell coinfection has occurred in the past and has shaped virus evolution by promoting the biogenesis of heterozygous virions and recombination during reverse transcription.
In vitro
experiments have shown that cell coinfection with HIV is more frequent than would be expected if coinfection were a random process. A possible explanation for this bias is the heterogeneity of target cells and the preferred infection of a subpopulation. To address this question, we compared the frequency of double-positive cells measured following coincubation with green fluorescent protein (GFP) and DsRed HIV reporter viruses with that of stochastic coinfection calculated as the product of the frequencies of GFP- and DsRed-positive cells upon incubation with either reporter virus. Coinfection was more frequent than would be expected on the grounds of stochastic infection, due to the underestimation of single-infection frequencies, which mathematically decreased the calculated frequency. Indeed, when cells were incubated with either reporter virus, a fraction of the cells were scored as uninfected yet harbored a silent provirus that was reactivated upon coinfection through cross talk between viral elements. When such cross talk was avoided, experimental and calculated coinfection frequencies matched, indicating random coinfection. The proportion of infected cells harboring a silent provirus was estimated from coinfection experiments and was shown to be cell type dependent but independent of the virus entry route.
Younger age of menopause in women with cerebral aneurysms
Authors: Ding Christine , Toll Valerie , Ouyang Bichun , Chen Michael
Published: June 2012

Background

The incidence of subarachnoid hemorrhage in women surges following menopause. Estrogen fluctuations have been implicated in cerebral aneurysm formation, growth and rupture and are thought to explain the well-known gender disparity. The aim of this study was to examine the association between age at menopause, which can determine lifetime estrogen exposure, and the presence of cerebral aneurysms.

Methods

A retrospective case-control study was conducted by interviewing postmenopausal women with intradural cerebral aneurysms about their basic medical and gynecologic histories. This information was compared with the same data points collected from 4682 women contacted through random digit phone dialing in the National Institute of Child Health and Human Development-sponsored Contraceptive and Reproductive Experiences Study published in 2002.

Results

Among 76 consecutive postmenopausal women with cerebral aneurysms who were treated by a single physician and interviewed, multivariate logistic regression showed that later menopause age (OR 0.79, CI 0.63 to 0.996, p=0.046) was significantly associated with a lower aneurysm incidence. Premature menopause (<40 years) was seen in 26% of cases and 19% of controls (p=0.15). Each categorical increase in menopause age (<40, 40–44, 45–49, 50–54, ≥55 years) decreased the likelihood by 21%. Despite a trend towards earlier mean age at menopause in the case group, the difference was not statistically significant.

Conclusion

There is a trend showing that an earlier age at menopause is associated with the presence of a cerebral aneurysm. This suggests that loss of estrogen earlier in a woman's life may contribute to the pathogenesis of cerebral aneurysm. These data may identify a risk factor for cerebral aneurysm pathogenesis and also a potential target for future therapies.
THE ANALYSIS OF THE ATOMIC PAIR DISTRIBUTION FUNCTION OF PMN-BASED NANOPOWDERS BY X-RAY DIFFRACTION
Authors: GHASEMIFARD M. , KHORRAMI GH. H.
Published: June 2012

The three-dimensional atomic-scale structure around Mg , Nb , Ti and Zr atoms in a series ferroelectric material such as PMN, PZT, PMN-PZT and PMN-PT has been studied using X-ray diffraction ( MoK α), Rietveld refinement and the atomic pair distribution function (PDF) technique. The structure and particle size of the powders was determined by X-ray diffraction and TEM observation. The studies show that the materials are disordered at nanometer length distances. The three-dimensional atomic ordering in PMN-based nanopowders may well be described by a cubic structure of the perovskite type, similar to that occurring in the bulk crystals. At the end, the analyzed data show that the sizes of ZrO 6 octahedral are larger than TiO 6 octahedral.
NUMERICAL STUDY OF THE INTERACTION BETWEEN POSITIVE AND NEGATIVE MASS OBJECTS IN GENERAL RELATIVITY
Authors: CAO ZHOUJIAN
Published: June 2012

Based on Baumgarte–Shapiro–Shibata–Nakamura formalism and moving puncture method, we demonstrate the first numerical evolutions of the interaction between positive and negative mass objects. Using the causal property of general relativity, we set our computational domain around the positive mass black hole while excluding the region around the naked singularity introduced by the negative mass object. Besides the usual Sommerfeld numerical boundary condition, an approximate boundary condition is proposed for this nonasymptotically-flat computational domain. Careful checks show that either boundary condition introduces smaller error than the numerical truncation errors. This is consistent with the causal property of general relativity. Except for the numerical truncation error and round-off error, our method gives an exact solution to the full Einstein's equation for a portion of spacetime with two objects whose masses have opposite signs. So our method opens the door for numerical explorations with negative mass objects. Based on this method, we investigate the Newtonian limit of spacetime with two objects whose masses have opposite sign. Our result implies that this spacetime does have a Newtonian limit which corresponds to a negative mass particle chasing a positive mass particle. This result sheds some light on an interesting debate about the Newtonian limit of a spacetime with positive and negative point masses.
THE EFFECT OF MAGNETIC THERAPY AND ACTIVE EXERCISE ON BONE MINERAL DENSITY IN ELDERLY WOMEN WITH OSTEOPOROSIS
Authors: Shanb Al-Sayed A. , Youssef Enas F. , El-Barkouky Mohamed G. , Kamal Rasha M. , Tawfick Ahmed M.
Published: June 2012

Purpose: To evaluate the effect of pulsed electro-magnetic therapy and exercise training on bone mineral density (BMD) in elderly women with osteoporosis. Material and Methods: A total of 30 elderly women with osteoporosis aged from 60 to 70 years old were randomly divided into two groups: A magnetic group consisting of 15 women who received pulsed electro-magnetic therapy at a frequency of 33 Hz and an intensity of 50 gauss for 50 min per session and an exercise group consisting of 15 women who practiced active exercises that included treadmill walking and selected exercises for hip and back muscles for 50 min per session. Both interventions were applied for three sessions/week for three months at a physical therapy clinic. Dual-energy X-ray absorptiometry was used to measure the BMD of the neck of the femur and the lumbar spine (L3-L5) before and after intervention. Results: Statistical analysis revealed that the BMD of the neck of the femur and the lumbar spine significantly increased in the two groups without a significant difference between them. Conclusion: Pulsed electro-magnetic therapy and exercises can increase BMD at the neck of the femur and the lumbar spine in elderly women. Physical therapists could apply pulsed electro-magnetic therapy or exercise training to increase BMD in elderly women.
PRICING OF UNEMPLOYMENT INSURANCE PRODUCTS WITH DOUBLY STOCHASTIC MARKOV CHAINS
Authors: BIAGINI FRANCESCA , WIDENMANN JAN
Published: June 2012

This paper provides a new approach for modeling and calculating premiums for unemployment insurance products. The innovative modeling concept consists of combining the benchmark approach with its real-world pricing formula and Markov chain techniques in a doubly stochastic setting. We describe individual insurance claims based on a special type of unemployment insurance contracts, which are offered on the private insurance market. The pricing formulas are first given in a general setting and then specified under the assumption that the individual employment-unemployment process of an employee follows a time-homogeneous doubly stochastic Markov chain. In this framework, formulas for the premiums are provided depending on the ℙ-numéraire portfolio of the benchmark approach. Under a simple assumption on the ℙ-numéraire portfolio, the model is tested on its sensitivities to several parameters. With the same specification the model's employment and unemployment intensities are estimated on public data of the Federal Employment Office in Germany.
CONSISTENT FACTOR MODELS FOR TEMPERATURE MARKETS
Authors: HELL PHILIPP , MEYER-BRANDIS THILO , RHEINLÄNDER THORSTEN
Published: June 2012

We propose an approach for pricing and hedging weather derivatives based on including forward looking information about the temperature available to the market. This is achieved by modeling temperature forecasts by a finite dimensional factor model. Temperature dynamics are then inferred in the short end. In analogy to interest rate theory, we establish conditions which guarantee consistency of a factor model with the martingale dynamics of temperature forecasts. Finally, we consider a specific two-factor model and examine in more detail pricing and hedging of weather derivatives in this context.