A Variable Kinematic One-Dimensional Model for the Hygro-Mechanical Analysis of Composite Materials

Composite materials are widely used in many engineering fields. Their mechanical properties allow very stiff structures to be obtained with a mass reduction with respect to metallic materials. These materials are built using a polymeric matrix reinforced with high strength fibres, e.g. carbon fibres. The use of a polymeric matrix makes composite materials subject to aging effects and in particular their properties and performances may be reduced because of the moisture absorption. An accurate prediction of the deformations and of the internal stress field due to the hygro-mechanical effects is mandatory in the design of a composite structure exposed to a moisture concentration. Classical structural models, beams and plates, cannot provide a complete three-dimensional stress field because their kinematic assumption, e.g. rigid crosssection for the beam of constant thickness for the plates. These limitations make the classical models inaccurate when complex three-dimensional stress fields have to be evaluated as in the case of the hygro-mechanical problem, that is, a full three-dimensional model must be used. The present paper proposes to use a refined one-dimensional model with variable kinematic, developed in the frameworks of the Carrera Unified Formulation (CUF), for the hygromechanical analysis of composite structures. Refined one-dimensional models are able to overcome the limitations of the classical beam models thanks to a refined kinematic fields, used over the cross-section, able to provide a full three-dimensional solution. In this work a model based on Lagrange functions is used. The hygro-mechanical model has been derived in the CUF frameworks, that is, the moisture concentration can be considered as a variable of the problem. The moisture concentration has been evaluated solving analytically the Fick law that is able to provide the moisture distribution after a certain time of exposure. The moisture concentration has been used as boundary condition in the hygro-mechanical problem in order to evaluate the displacement and stress fields. The model has been assessed and the results have been compare with those from classical threedimensional FE models. Displacements field, stress field and the volume variation have been used to compare the accuracy of the solution. The results show that the refined one-dimensional models are able to provide an accurate solution with a lower computational cost with respect to the full three-dimensional FE models

Regional and Hemispheric Determinants of Language Laterality: Implications for Preoperative fMRI

Language is typically a function of the left hemisphere but the right hemisphere is also essential in some healthy individuals and patients. This inter-subject variability necessitates the localization of language function, at the individual level, prior to neurosurgical intervention. Such assessments are typically made by comparing left and right hemisphere language function to determine “language lateralization” using clinical tests or fMRI. Here, we show that language function needs to be assessed at the region and hemisphere specific level, because laterality measures can be misleading. Using fMRI data from 82 healthy participants, we investigated the degree to which activation for a semantic word matching task was lateralized in 50 different brain regions and across the entire cortex. This revealed two novel findings. First, the degree to which language is lateralized across brain regions and between subjects was primarily driven by differences in right hemisphere activation rather than differences in left hemisphere activation. Second, we found that healthy subjects who have relatively high left lateralization in the angular gyrus also have relatively low left lateralization in the ventral precentral gyrus. These findings illustrate spatial heterogeneity in language lateralization that is lost when global laterality measures are considered. It is likely that the complex spatial variability we observed in healthy controls is more exaggerated in patients with brain damage. We therefore highlight the importance of investigating within hemisphere regional variations in fMRI activation, prior to neuro-surgical intervention, to determine how each hemisphere and each region contributes to language processing. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc

Motor Outcomes After Neonatal Arterial Ischemic Stroke Related to Early MRI Data in a Prospective Study

OBJECTIVE: We aimed to correlate early imaging data with motor outcomes in a large, homogeneous, cohort of infants with neonatal (diagnosed before 29 days of life) arterial ischemic stroke (AIS).METHODS: From a prospective cohort of 100 children with neonatal AIS, we analyzed the MRI studies performed within the 28 first days of life for 80 infants evaluated at 2 years of age. The relationships between infarction location and corticospinal tract (CST) involvement and motor outcomes were studied RESULTS: Seventy-three infarctions involved the middle cerebral artery (MCA) territory. Of those, 50 were superficial infarctions, 5 deep infarctions, and 18 mixed infarctions. The CST was involved in 24 cases. Nineteen patients with MCA infarctions (26% [95% confidence interval: 16%–34%]) developed hemiplegia. Mixed infarctions (P < .0001) and CST involvement (P < .0001) were highly predictive of hemiplegia. In contrast, 88% of children with isolated superficial MCA infarctions did not exhibit impairment. CONCLUSIONS: Accurate prediction of motor outcomes can be obtained from early MRI scans after neonatal AIS. The absence of involvement of the CST resulted in normal motor development in 94% of cases. CST involvement resulted in congenital hemiplegia in 66% of cases

Carcass characteristics and beef quality of young grass-fed Angus x Salers bovines

To characterize carcass and meat attributes, such as beef eating quality in specific farming conditions, 31 young grass-fed crossbred Angus x Salers cattle in two farming systems (a mono-cattle system versus a mixed system with beef cattle and sheep) were used in this study. Three muscle cuts (striploin—m. longissimus dorsi et thoracis; bolar blade—m. triceps brachii caput longum; internal flank plate—m. obliquus internus abdominis) were used for consumer eating quality testing and striploin was used for panelist eating quality assessment, and objective measurements [Warner–Bratzler shear force (WBSF) and fatty acid (FA) and antioxidant contents]. Results indicated that the farming system had no impact on carcass characteristics or meat quality, but it tended to affect FA content, which is likely explained by between-system differences in animal maturity (assessed by ossification score). Animal gender had significant effects on three eating quality traits evaluated by untrained consumers, with higher flavor liking, overall liking, and overall meat eating quality (MQ4) scores in females than in males. Additionally, FA contents were correlated with sensory quality traits to varying extents: consumer-scored tenderness, flavor, and overall liking were mainly positively correlated with ω-3 and ω-6 polyunsaturated fatty acid (PUFA) contents, and panelist-evaluated tenderness and abnormal flavor were more positively correlated with total lipids, saturated fatty acid (SFA), and monounsaturated fatty acid (MUFA) contents. Overall, this study showed that specific grass-fed crossbred Angus x Salers cattle can produce lean meat rich in ω-3 PUFAs with a low ω-6/ω-3 ratio and with “better than average” beef eating quality

After personalism: rethinking power transfers in Turkmenistan and Uzbekistan

What happens to elites when the personalistic leader they supported for so long suddenly dies? This article tackles comparatively transitions out of first presidencies in Turkmenistan and Uzbekistan, presenting an analytical framework that seeks to explain why these transitions unfolded in relatively smooth fashion. The overall stability defining power transfer processes instigated by the non-violent death of personalistic rulers in both contexts is explained here through the intersection of three key factors: the regimes’ resort to succession practices consolidated in the Soviet era, the emergence of temporary forms of collective decision-making in both transitional contexts, and the implementation of de-personalisation strategies pursuing the obliteration of specific pockets of cadres but stopping short of wider regime re-organisation. The findings of this article contribute to broader debates on the politics of de-personalisation, while putting forward a comprehensive framework to analyse transitions out of personalism in and beyond post-Soviet Eurasia

Typology of seismic motion and seismic engineering design

The paper deals with the influence of the seismic motion typology on the structural response and with engineering design under exceptional actions. Various aspects of seismic motion typology that lead to exceptional actions on the structures are covered. The influence of near fault ground motions, the effect of local site parameters and the magnification of the seismic action on short-period structures are among the parameters identified as dominant for the structural response. The paper presents also a methodology for handling uncertainty in engineering design, based on the mathematical framework of fuzzy analysis. Finally the paper presents various applications of performance based design, which is viewed as a tool as a tool for the analysis of structural behaviour under extreme seismic events. The influence of connection behaviour on the structural response is studied, and applications of the capacity design methodology and of the direct displacement design approach for the evaluation of reinforce concrete structures are presented

Doppler ultrasound in the measurement of pulse wave velocity: agreement with the Complior method

Aortic stiffness is an independent predictor factor for cardiovascular risk. Different methods for determining pulse wave velocity (PWV) are used, among which the most common are mechanical methods such as SphygmoCor or Complior, which require specific devices and are limited by technical difficulty in obtaining measurements. Doppler guided by 2D ultrasound is a good alternative to these methods. We studied 40 patients (29 male, aged 21 to 82 years) comparing the Complior method with Doppler. Agreement of both devices was high (R = 0.91, 0.84-0.95, 95% CI). The reproducibility analysis revealed no intra-nor interobserver differences. Based on these results, we conclude that Doppler ultrasound is a reliable and reproducible alternative to other established methods for the measurement of aortic PWV

Measurement of Creep Deformation across Welds in 316H Stainless Steel Using Digital Image Correlation

Spatially resolved measurement of creep deformation across weldments at high temperature cannot be achieved using standard extensometry approaches. In this investigation, a Digital Image Correlation (DIC) based system has been developed for long-term high-temperature creep strain measurement in order to characterise the material deformation behaviour of separate regions of a multi-pass weld. The optical system was sufficiently stable to allow a sequence of photographs to be taken suitable for DIC analysis of creep specimens tested at a temperature of 545 °C for over 2000 h. The images were analysed to produce local creep deformation curves from two cross-weld samples cut from contrasting regions of a multi-pass V-groove weld joining thick-section AISI Type 316H austenitic stainless steel. It is shown that for this weld, the root pass is the weakest region of the structure in creep, most likely due to the large number of thermal cycles it has experienced during the fabrication process. The DIC based measurement method offers improved spatial resolution over conventional methods and greatly reduces the amount of material required for creep characterisation of weldments

C.E.R.A. once every 4 weeks corrects anaemia and maintains haemoglobin in patients with chronic kidney disease not on dialysis

Background. No previous randomized controlled studies have been reported examining de novo, once every 4 weeks (Q4W) administration of erythropoiesis-stimulating agents in chronic kidney disease (CKD) patients. We report results from a randomized multinational study that compared continuous erythropoietin receptor activator (C.E.R.A.) Q4W with darbepoetin alfa once weekly (QW) or every 2 weeks (Q2W) for the correction of anaemia in non-dialysis CKD patients