Computational Homogenization of Architectured Materials

Architectured materials involve geometrically engineered distributions of microstructural phases at a scale comparable to the scale of the component, thus calling for new models in order to determine the effective properties of materials. The present chapter aims at providing such models, in the case of mechanical properties. As a matter of fact, one engineering challenge is to predict the effective properties of such materials; computational homogenization using finite element analysis is a powerful tool to do so. Homogenized behavior of architectured materials can thus be used in large structural computations, hence enabling the dissemination of architectured materials in the industry. Furthermore, computational homogenization is the basis for computational topology optimization which will give rise to the next generation of architectured materials. This chapter covers the computational homogenization of periodic architectured materials in elasticity and plasticity, as well as the homogenization and representativity of random architectured materials

Correlation between Bronchoalveolar Lavage (Bal) Fluid Cell Lysate Histamine Content and Bal Fluid Eosinophil Count in Atopic and Nonatopic Asthmatics

We have compared the bronchoalveolar lavage fluid (BAL) cellular composition and the BAL cell lysate histamine content (fluorometric assay) in 28 stable mild to moderate asthmatics (atopic n = 18 and intrinsic n = 10) and 11 control subjects. When compared to control subjects, the whole group of asthmatics had a higher proportion of BAL eosinophils (p < 0.01) and metachromatic cells (p < 0.05). The BAL cell lysate histamine was increased in atopic (p < 0.05) and intrinsic asthmatics (p < 0.05) in comparison with control subjects. In the whole group of asthmatics, the BAL cell lysate histamine content correlated with the percentage of BAL eosinophils (r = 0.58, p < 0.01). This relationship was significant in both atopic (r = 0.48, p < 0.05) and intrinsic (r = 0.70, p < 0.05) asthmatics. For the whole group of asthmatics, both the BAL cell lysate histamine and the percentage of BAL eosinophils inversely correlated with the percent predicted FEV1 (r = -0.42, p < 0.05; r = -0.51, p < 0.05). We conclude that an increased BAL cell lysate histamine content correlates with airway eosinophilic infiltration and lung function impairment in mild to moderate atopic and intrinsic asthmatics. This suggests that BAL mast cells play a key role in recruiting eosinophils in the airways of asthmatics irrespective of the presence of an atopic status

Characterization of acute and chronic myocardial infarcts by multidetector computed tomography: comparison with contrast-enhanced magnetic resonance.

BACKGROUND: We evaluated whether contrast-enhanced multidetector computed tomography (CE-MDCT) might characterize myocardial infarct (MI) with patterns similar to those obtained by contrast-enhanced magnetic resonance (CE-MR) and studied the underlying mechanisms. METHODS AND RESULTS: In vivo infarct characterization by CE-MDCT was shown to be feasible between 4 and 20 minutes after contrast injection in 7 pigs with MI. Subsequently, in 16 patients with acute MI and 21 patients with chronic MI, contrast patterns by CE-MDCT were related to CE-MR. Eighteen patients had hypoenhanced regions on early CE-MDCT images at the time of coronary imaging, and 34 patients had hyperenhanced regions on images acquired 10 minutes later. On a segmental basis, there was moderately good concordance of early hypoenhanced regions (92%, kappa=0.54, P<0.001) and late hyperenhanced regions (82%, kappa=0.61, P<0.001) between CE-MDCT and CE-MR. Absolute sizes of early hypoenhanced (6+/-16 versus 7+/-16 g, P=0.25) and late hyperenhanced (36+/-34 versus 31+/-40 g, P=0.14) regions were similar on CE-MDCT and CE-MR and were highly correlated (r=0.93, P<0.001 and r=0.89, P<0.001 respectively). In 8 retrogradely perfused infarcted rabbit hearts, contrast kinetics of iomeprol were similar to gadodiamide, ie, slow wash in (8.7+/-6.7 versus 1.2+/-0.3 minutes, P<0.001) in infarct core and slow washout (20+/-12 versus 2.5+/-0.5 minutes, P<0.001) in both infarct core and rim compared with the remote region. CONCLUSIONS: Because iodated contrast agents have similar kinetics in infarcted and noninfarcted myocardium as gadolinium DPTA, CE-MDCT can characterize acute and chronic MI with contrast patterns similar to CE-MR. CE-MDCT may thus provide important information on infarct size and viability at the time of noninvasive coronary imaging

Internal stress and opto-electronic properties of ZnO thin films deposited by reactive sputtering in various oxygen partial pressures

In this article, we propose ZnO thin films as a suitable material for piezoresistors in transparent and flexible electronics. ZnO thin films have been deposited by DC reactive magnetron sputtering at room temperature at various oxygen partial pressures. All the films have a wurtzite structure with a strong (0002) texture measured by XRD and are almost stoichiometric as measured by inductively coupled plasma optical emission spectroscopy. The effect of oxygen concentration on grain growth has been studied by in-situ multi-beam optical stress sensor, showing internal stress going from 350 MPa to −1.1 GPa. The transition between tensile and compressive stress corresponds to the transition between metallic and oxidized mode of reactive sputtering. This transition also induces a large variation in optical properties—from absorbent to transparent, and in the resistivity—from 4×10−2Ω.cm to insulating. Finally, the piezoresistance of the thin film has been studied and showed a gauge factor (ΔR/R)/ε comprised between −5.8 and −8.5

Convection and interfacial mass exchange

peer reviewedMass-exchange through fluid interfaces is ubiquitous in many natural and industrial processes. Yet even basic phase-change processes such as evaporation of a pure liquid are not fully understood, in particular when coupled with fluid motions in the vicinity of the phase-change interface, or with microscopic physical phenomena in the vicinity of a triple line (where the interface meets a solid). Nowadays, many industries recognise that this lack of fundamental knowledge is hindering the optimisation of existing processes. Their modelling tools are too dependent on empirical correlations with a limited - and often unknown - range of applicability. In addition to the intrinsic multiscale nature of the phenomena involved in typical industrial processes linked to interfacial mass exchange, their study is highly multi-disciplinary, involving tools and techniques belonging to physical chemistry, chemical engineering, fluid dynamics, non-linear physics, non-equilibrium thermodynamics, chemistry and statistical physics. From the experimental point of view, microgravity offers a unique environment to obtain valuable data on phase-change processes, greatly reducing the influence of body forces and allowing the detailed and accurate study of interfacial dynamics. In turn, such improved understanding leads to optimisation of industrial processes and devices involving phase-change, both for space and ground applications

Multi-level factors are associated with immunosuppressant nonadherence in heart transplant recipients: the international bright study

Factors at the level of family/healthcare worker-, organization- and system are neglected in medication nonadherence research in heart transplantation (HTx). The four-continent, eleven-country cross-sectional BRIGHT study used multi-staged sampling to examine 36 HTx centers, including 36 HTx directors, 100 clinicians, and 1397 patients. Nonadherence to immunosuppressants-defined as any deviation in taking or timing adherence and/or dose reduction-was assessed using the BAASIS® interview. Guided by the Integrative Model of Behavioral Prediction and Bronfenbrenner's ecological model, we analyzed factors at these multiple levels using sequential logistic regression analysis (6 blocks). The nonadherence prevalence was 34.1%. Six multi-level factors were associated independently (either positively or negatively) with nonadherence: patient level: barriers to taking immunosuppressants (OR: 11.48); smoking (OR:2.19); family/healthcare provider level: frequency of having someone to help patients read health-related materials (OR:0.85); organization level: clinicians reporting non-adherent patients were targeted with adherence interventions (OR: 0.66); pick-up of medications at physician's office (OR: 2.31); and policy level: monthly out-of-pocket costs for medication (OR: 1.16). Factors associated with nonadherence are evident at multiple levels. Improving medication nonadherence requires addressing not only the patient, but also family/healthcare provider, organization, and policy levels. This article is protected by copyright. All rights reserved.status: accepte

Control of Dog Mediated Human Rabies in Haiti: No Time to Spare.

The American region has pledged to eliminate dog-mediated human rabies by 2015. As part of these efforts, we describe the findings of a desk and field mission review of Haiti's rabies situation by the end of 2013. While government officials recognize the importance of dog-mediated rabies control, and the national rabies plan adequately contemplates the basic capacities to that effect, regular and sufficient implementation, for example, of dog vaccination, is hampered by limited funding. Compounding insufficient funding and human resources, official surveillance figures do not accurately reflect the risk to the population, as evidenced by the large number of rabid dogs detected by focalized and enhanced surveillance activities conducted by the Ministry of Agriculture, Natural Resources and Rural Development (MARNDR) and the Health and Population Ministry (MSPP) with the technical assistance of the United States Centers for Disease Control and Prevention. Although international support is common, either in the form of on-the-ground technical support or donations of immunobiologicals, it is not comprehensive. In addition, there is limited coordination with MARNDR/MSPP and with other actors at the strategic or operational level due to human resources limitations. Given these findings, the 2015 elimination goal in the region is compromised by the situation in Haiti where control of the disease is not yet in sight despite the best efforts of the resolute national officials. More importantly, dog-mediated rabies is still a threat to the Haitian population

Solar panels at an outpost in Haiti.

<p>Electricity is fed to refrigerators inside the post to ensure cold chain for canine rabies vaccine.</p

Distinctive Effects of CCR5, CCR2, and SDF1 Genetic Polymorphisms in AIDS Progression

The Genetics of Resistance to Infection by HIV-1 (GRIV) cohort represents 200 nonprogressor/slow-progressor (Slowprog) and 90 fast-progressor (Fastprog) HIV-1-infected patients. Using this unique assembly, we performed genetic studies on three recently discovered polymorphisms of CCR5, CCR2, and SDFI, which have been shown to slow the rate of disease progression. The increased prevalence of mutant alleles among Slowprogs from the GRIV cohort was significant for CCR5 (p \u3c .0001) but not for CCR2 (p = .09) or SDF1 (p = .12), emphasizing the predominant role of CCR5 as the major HIV-1 coreceptor. However, the prevalence of the CCR2 mutant allele (64I) was significantly increased among Slowprogs homozygous for wild-type CCR5 compared with Fastprogs (p = .04). The prevalence of double mutants SDF1- 3\u27A/3\u27A genotypes was also increased among Slowprogs homozygous for wild-type CCR5 compared with Fastprogs (p = .05). The effects of the CCR2 and SDF1 mutations are overshadowed by the protective effects of the CCR5 deletion. Predictive biologic markers such as CD4 cell counts or viral load in the Slowprog population did not show significant differences between Slowprog groups with wild-type or mutant alleles for the three genes. Thus, our data suggest that the effects of these genes are exerted earlier in infection and no longer evident in the Slowprog of the GRIV cohort whose average duration of HIV infection is 12 years. We conclude that these genes, whose products serve as viral coreceptors or their ligands, may play a role early in infection and delay the onset of disease. However, among Slowprogs, whose duration of infection is \u3e8 years, they are no longer influential for maintenance of their longterm nonprogression status. Other genetic determinants may be responsible for late protective effects