Evaluation of constitutive models for springback prediction in U-draw/bending of DP and TRIP steel sheets

U-draw/bending experiments and simulations were performed to investigate the characteristics of springback in sheet metals. The finite element method is frequently used for the simulation of springback, but the predictions are strongly influenced by the constitutive models such as yield criteria and hardening laws. In the present study, springback of DP and TRIP steel sheets after U-draw/bending was predicted with a finite element analysis. Various yield functions were considered, namely, the isotropic von Mises and anisotropic Hill models. For strain hardening, isotropic, non-linear kinematic and combined isotropic-kinematic hardening models were considered. In order to characterize the isotropic hardening behavior, both uniaxial and balanced biaxial (hydraulic bulge) tension tests were carried out. For the characterization of the combined isotropic-kinematic hardening model, forward-reverse simple shear tests were conducted. The springback predictions were greatly influenced by the choice of the hardening model but slightly affected by the choice of the yield criterion. The kinematic hardening and combined isotropic-kinematic hardening models provided satisfactory predictions for DP590 and TRIP590 sheets, respectively. Due to an extended measurable strain range, the use of the flow curves from the hydraulic bulge test led to more reliable results than those of uniaxial tension.ope

Monte Carlo Simulations of Globular Cluster Evolution. VI. The Influence of an Intermediate Mass Black Hole

We present results of a series of Monte Carlo simulations investigating the imprint of a central intermediate-mass black hole (IMBH) on the structure of a globular cluster. We investigate the three-dimensional and projected density profiles, and stellar disruption rates for idealized as well as realistic cluster models, taking into account a stellar mass spectrum and stellar evolution, and allowing for a larger, more realistic, number of stars than was previously possible with direct N-body methods. We compare our results to other N-body and Fokker-Planck simulations published previously. We find, in general, very good agreement for the overall cluster structure and dynamical evolution between direct N-body simulations and our Monte Carlo simulations. Significant differences exist in the number of stars that are tidally disrupted by the IMBH, which is most likely an effect of the wandering motion of the IMBH, not included in the Monte Carlo scheme. These differences, however, are negligible for the final IMBH masses in realistic cluster models as the disruption rates are generally much lower than for single-mass clusters. As a direct comparison to observations we construct a detailed model for the cluster NGC 5694, which is known to possess a central surface brightness cusp consistent with the presence of an IMBH. We find that not only the inner slope but also the outer part of the surface brightness profile agree well with observations. However, there is only a slight preference for models harboring an IMBH compared to models without.Comment: 37 pages, 10 figures, Accepted for publication in ApJ Supplement. Substantial additions on modeling NGC 5694 since original versio

Artemisinin resistance in Plasmodium falciparum malaria.

BACKGROUND: Artemisinin-based combination therapies are the recommended first-line treatments of falciparum malaria in all countries with endemic disease. There are recent concerns that the efficacy of such therapies has declined on the Thai-Cambodian border, historically a site of emerging antimalarial-drug resistance. METHODS: In two open-label, randomized trials, we compared the efficacies of two treatments for uncomplicated falciparum malaria in Pailin, western Cambodia, and Wang Pha, northwestern Thailand: oral artesunate given at a dose of 2 mg per kilogram of body weight per day, for 7 days, and artesunate given at a dose of 4 mg per kilogram per day, for 3 days, followed by mefloquine at two doses totaling 25 mg per kilogram. We assessed in vitro and in vivo Plasmodium falciparum susceptibility, artesunate pharmacokinetics, and molecular markers of resistance. RESULTS: We studied 40 patients in each of the two locations. The overall median parasite clearance times were 84 hours (interquartile range, 60 to 96) in Pailin and 48 hours (interquartile range, 36 to 66) in Wang Pha (P<0.001). Recrudescence confirmed by means of polymerase-chain-reaction assay occurred in 6 of 20 patients (30%) receiving artesunate monotherapy and 1 of 20 (5%) receiving artesunate-mefloquine therapy in Pailin, as compared with 2 of 20 (10%) and 1 of 20 (5%), respectively, in Wang Pha (P=0.31). These markedly different parasitologic responses were not explained by differences in age, artesunate or dihydroartemisinin pharmacokinetics, results of isotopic in vitro sensitivity tests, or putative molecular correlates of P. falciparum drug resistance (mutations or amplifications of the gene encoding a multidrug resistance protein [PfMDR1] or mutations in the gene encoding sarco-endoplasmic reticulum calcium ATPase6 [PfSERCA]). Adverse events were mild and did not differ significantly between the two treatment groups. CONCLUSIONS: P. falciparum has reduced in vivo susceptibility to artesunate in western Cambodia as compared with northwestern Thailand. Resistance is characterized by slow parasite clearance in vivo without corresponding reductions on conventional in vitro susceptibility testing. Containment measures are urgently needed. (ClinicalTrials.gov number, NCT00493363, and Current Controlled Trials number, ISRCTN64835265.

The Relation Between Halo Shape, Velocity Dispersion and Formation Time

We use dark matter haloes identified in the MareNostrum Universe and galaxy groups identified in the Sloan Data Release 7 galaxy catalogue, to study the relation between halo shape and halo dynamics, parametrizing out the mass of the systems. A strong shape-dynamics, independent of mass, correlation is present in the simulation data, which we find it to be due to different halo formation times. Early formation time haloes are, at the present epoch, more spherical and have higher velocity dispersions than late forming-time haloes. The halo shape-dynamics correlation, albeit weaker, survives the projection in 2D (ie., among projected shape and 1-D velocity dispersion). A similar shape-dynamics correlation, independent of mass, is also found in the SDSS DR7 groups of galaxies and in order to investigate its cause we have tested and used, as a proxy of the group formation time, a concentration parameter. We have found, as in the case of the simulated haloes, that less concentrated groups, corresponding to late formation times, have lower velocity dispersions and higher elongations than groups with higher values of concentration, corresponding to early formation times.Comment: MNRAS in press (10 pages, 10 figures

Dating Violence: Outcomes Following a Brief Motivational Interviewing Intervention Among At‐risk Adolescents in an Urban Emergency Department

Objectives A recent study demonstrated the efficacy of the SafERteens intervention in reducing peer violence among adolescents presenting to the emergency department (ED). The objective of this study was to determine the efficacy of this ED‐based brief intervention (BI) on dating violence 1 year following the ED visit among the subsample of adolescents in the original randomized controlled trial reporting past‐year dating violence. Methods Patients (aged 14 to 18 years) at an ED were eligible for inclusion if they had past‐year violence and alcohol use. Participants were randomized to one of three conditions (BI delivered by a computer [CBI], BI delivered by a therapist and a computer (T+CBI), or control) and completed follow‐ups at 3, 6, and 12 months. In addition to content on alcohol misuse and peer violence, adolescents reporting dating violence received a tailored module on dating violence. The outcome of interest was frequency of moderate and severe dating violence victimization and aggression (baseline and 3, 6, and 12 months after ED visit). Results Among eligible adolescents, 55% ( n  = 397) reported dating violence and were included in these analyses. Compared to the control group (who received a resource brochure only), participants in the CBI showed reductions in moderate dating victimization at 3 months (inter‐rater reliability [IRR] = 0.71; 95% confidence interval [CI] = 0.51 to 0.99; p < 0.05) and 6 months (IRR = 0.56; 95% CI = 0.38 to 0.83; p < 0.01). Models examining interaction effects were significant for the CBI on moderate dating victimization at 3 months (IRR = 0.81; 95% CI = 0.67 to 0.98; p < 0.05) and 6 months (IRR = 0.81; 95% CI = 0.66 to 0.99; p < 0.05). Significant interaction effects were found for the T+CBI on moderate dating violence victimization at 6 months (IRR = 0.81; 95% CI = 0.69 to 0.96; p < 0.01) and 12 months (IRR = 0.76; 95% CI = 0.63 to 0.90; p < 0.001) and severe dating violence victimization at 3 months (IRR = 0.76; 95% CI = 0.59 to 0.96; p < 0.05). Conclusions ED‐based BIs tailored to address multiple risk behaviors (i.e., peer violence, alcohol use, and dating violence) show promise for reducing moderate and severe dating victimization for up to 1 year following an ED visit. Resumen La Violencia de Pareja: Resultados tras una Intervención mediante una Entrevista Breve Motivacional entre los Adolescentes en Riesgo en un Servicio de Urgencias Urbano Objetivos Un estudio reciente demostró la eficacia de la intervención SafERteens en reducir la violencia entre los adolescentes que acuden al servicio de urgencias (SU). El objetivo de este estudio fue determinar la eficacia de esta intervención breve (IB) en los SU en la violencia de pareja al año tras la visita al SU en una muestra de adolescentes del ensayo clínico original controlado y aleatorizado que documentó la violencia de pareja del pasado año. Metodología Se incluyeron los pacientes entre 14 y 18 años de edad del SU que tenían antecedentes de violencia o consumo de alcohol en el pasado año. Los participantes fueron aleatorizados a una de las tres situaciones: IB realizada por un ordenador (IBO), IB realizada por un terapeuta y un ordenador (IBO + T), o control; y completaron 3, 6, y 12 meses de seguimiento. Además de contener abuso de alcohol y violencia entre iguales, los adolescentes que documentaron la violencia de pareja recibieron un módulo adaptado en violencia de pareja. El resultado de interés fue la frecuencia de violencia de pareja moderada o grave como víctima y agresor (basal, 3, 6 y 12 meses tras la visita). Resultados Entre los adolescentes elegibles, el 55% (n=397) documentó datos de violencia de pareja y fueron incluidos en estos análisis. En comparación con el grupo control (que recibieron sólo el recurso de un folleto informativo), los participantes en la IBO mostraron una reducción en la violencia de pareja moderada como víctima a los 3 meses (concordancia entre evaluadores [K] 0,71; IC 95% = 0,51 a 0,99; p < 0,05) y a los 6 meses (K 0,56; IC 95%= 0,38 a 0,83; p < 0,01); los modelos que examinaron los efectos de interacción fueron significativos para la IBO en la violencia de pareja moderada como víctima a los 3 meses (K 0,81; IC 95% = 0,67 a 0,98; p < 0,05) y a los 6 meses (K 0,81; IC 95% = 0,66 a 0,99; p < 0,05). Se hallaron efectos de interacción significativos para la IBO+T en la violencia de pareja moderada como víctima a los 6 meses (K 0,81; IC 95% = 0,69 a 0,96; p < 0,01) y a los 12 meses (K 0,76; IC 95% = 0,63 a 0,90; p < 0,001), y en la violencia de pareja grave como víctima a los 3 meses (K 0.76; IC 95% = 0,59 a 0,96; p < 0,05). Conclusiones Las IB en el SU adaptadas para valorar múltiples comportamientos de riesgo (ej: violencia entre iguales, consumo de alcohol y violencia de pareja) son prometedores para reducir la violencia de pareja moderada y grave como víctima hasta un año tras la visita al SU.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98214/1/acem12151.pd

Biomarkers of browning of white adipose tissue and their regulation during exercise- and diet-induced weight loss

Background: A hypothesis exists whereby an exercise- or dietary-induced negative energy balance reduces human subcutaneous white adipose tissue (scWAT) mass through the formation of brown-like adipocyte (brite) cells. However, the validity of biomarkers of brite formation has not been robustly evaluated in humans, and clinical data that link brite formation and weight loss are sparse. Objectives: We used rosiglitazone and primary adipocytes to stringently evaluate a set of biomarkers for brite formation and determined whether the expression of biomarker genes in scWAT could explain the change in body composition in response to exercise training combined with calorie restriction in obese and overweight women (n = 79). Design: Gene expression was derived from exon DNA microarrays and preadipocytes from obesity-resistant and -sensitive mice treated with rosiglitazone to generate candidate brite biomarkers from a microarray. These biomarkers were evaluated against data derived from scWAT RNA from obese and overweight women before and after supervised exercise 5 d/wk for 16 wk combined with modest calorie restriction (∼0.84 MJ/d). Results: Forty percent of commonly used brite gene biomarkers exhibited an exon or strain-specific regulation. No biomarkers were positively related to weight loss in human scWAT. Greater weight loss was significantly associated with less uncoupling protein 1 expression (P = 0.006, R(2) = 0.09). In a follow-up global analysis, there were 161 genes that covaried with weight loss that were linked to greater CCAAT/enhancer binding protein α activity (z = 2.0, P = 6.6 × 10(−7)), liver X receptor α/β agonism (z = 2.1, P = 2.8 × 10(−7)), and inhibition of leptin-like signaling (z = −2.6, P = 3.9 × 10(−5)). Conclusion: We identify a subset of robust RNA biomarkers for brite formation and show that calorie-restriction–mediated weight loss in women dynamically remodels scWAT to take on a more-white rather than a more-brown adipocyte phenotype

Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances, is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.Comment: 22 pages, 12 figures, review pape

Post-Newtonian SPH calculations of binary neutron star coalescence. II. Binary mass ratio, equation of state, and spin dependence

Using our new Post-Newtonian SPH (smoothed particle hydrodynamics) code, we study the final coalescence and merging of neutron star (NS) binaries. We vary the stiffness of the equation of state (EOS) as well as the initial binary mass ratio and stellar spins. Results are compared to those of Newtonian calculations, with and without the inclusion of the gravitational radiation reaction. We find a much steeper decrease in the gravity wave peak strain and luminosity with decreasing mass ratio than would be predicted by simple point-mass formulae. For NS with softer EOS (which we model as simple $\Gamma=2$ polytropes) we find a stronger gravity wave emission, with a different morphology than for stiffer EOS (modeled as $\Gamma=3$ polytropes as in our previous work). We also calculate the coalescence of NS binaries with an irrotational initial condition, and find that the gravity wave signal is relatively suppressed compared to the synchronized case, but shows a very significant second peak of emission. Mass shedding is also greatly reduced, and occurs via a different mechanism than in the synchronized case. We discuss the implications of our results for gravity wave astronomy with laser interferometers such as LIGO, and for theoretical models of gamma-ray bursts (GRBs) based on NS mergers.Comment: RevTeX, 38 pages, 24 figures, Minor Corrections, to appear in Phys. Rev.