An efficient quadrature rule on the cubed sphere

A new quadrature rule for functions defined on the sphere is introduced. The nodes are defined as the points of the Cubed Sphere. The associated weights are defined in analogy to the trapezoidal rule on each panel of the Cubed Sphere. The formula enjoys a symmetry property ensuring that a proportion of 7/8 of all Spherical Harmonics is integrated exactly. Based on the remaining Spherical Harmonics, it is possible to define modified weights giving an enhanced quad-rature rule. Numerical results show that the new quadrature is competitive with classical rules of the litterature. This second quadrature rule is believed to be of interest for applied mathematicians, physicists and engineers dealing with data located at the points of the Cubed Sphere

L'organisation, le climat et les conduites professionnelles

L'objectif de la recherche était d'illustrer la notion de climat social à travers l'étude de deux filiales d'une entreprise multinationale du bâtiment. Des interviews ont été effectuées auprès des ouvriers et de leurs contremaîtres, et 246 questionnaires ont été remplis, dont 188 traités par A.F.C. Le climat varie selon les ateliers et relève d'un équilibre assez fragile résultant de l'interaction de plusieurs variables : niveau de la production et par suite des primes, sentiment d'équité, style du leadership, vécu des tâches et des responsabilités, historique des groupes de travail, projets de vie (ouvriers à tradition industrielle vs ouvriers d'origine agricole).Climat social;Ouvriers;Communications;Equité

Extreme Mountain Ultra-Marathon Leads to Acute but Transient Increase in Cerebral Water Diffusivity and Plasma Biomarkers Levels Changes.

Background: Pioneer studies demonstrate the impact of extreme sport load on the human brain, leading to threatening conditions for athlete's health such as cerebral edema. The investigation of brain water diffusivity, allowing the measurement of the intercellular water and the assessment of cerebral edema, can give a great contribution to the investigation of the effects of extreme sports on the brain. We therefore assessed the effect of supra-physiological effort (extreme distance and elevation changes) in mountain ultra-marathons (MUMs) athletes combining for the first time brain magnetic resonance imaging (MRI) and blood parameters. Methods:This longitudinal study included 19 volunteers (44.2 ± 9.5 years) finishing a MUM (330 km, elevation + 24000 m). Quantitative measurements of brain diffusion-weighted images (DWI) were performed at 3 time-points: Before the race, upon arrival and after 48 h. Multiple blood biomarkers were simultaneously investigated. Data analyses included brain apparent diffusion coefficient (ADC) and physiological data comparisons between three time-points. Results:The whole brain ADC significantly increased from baseline to arrival (p = 0.005) and then significantly decreased at recovery (p = 0.005) to lower values than at baseline (p = 0.005). While sodium, potassium, calcium, and chloride as well as hematocrit (HCT) changed over time, the serum osmolality remained constant. Significant correlations were found between whole brain ADC changes and osmolality (p = 0.01), cholesterol (p = 0.009), c-reactive protein (p = 0.04), sodium (p = 0.01), and chloride (p = 0.002) plasma level variations. Conclusions:These results suggest the relative increase of the inter-cellular volume upon arrival, and subsequently its reduction to lower values than at baseline, indicating that even after 48 h the brain has not fully recovered to its equilibrium state. Even though serum electrolytes may only indirectly indicate modifications at the brain level due to the blood brain barrier, the results concerning osmolality suggest that body water might directly influence the change in cerebral ADC. These findings establish therefore a direct link between general brain inter-cellular water content and physiological biomarkers modifications produced by extreme sport

Simultaneous segmentation of the left and right heart ventricles in 3D cine MR images of small animals

New high resolution image techniques allow to capture the anatomy and movement of the heart of small animals. The availability of these in vivo images can be very useful for medical research, however the amount of generated data for large animal studies makes manual analysis a very tedious task. To cope with the problem of automatic analysis of these images, we propose the use of the Deformable Elastic Template method to perform automatic segmentation of the ventricles. To adapt the method to the specificities of high-resolution MRI, several improvements are presented, including an image-context dependent scheme for more robust segmentation. Qualitative results show that our method is able to correctly retrieve the heart’s contours in 3D. 1

Chemical-Shift-Encoded Magnetic Resonance Imaging and Spectroscopy to Reveal Immediate and Long-Term Multi-Organs Composition Changes of a 14-Days Periodic Fasting Intervention: A Technological and Case Report

Objectives: The aim of this study was to investigate the feasibility of measuring the effects of a 14-day Periodic Fasting (PF) intervention (<200 cal) on multi-organs of primary interest (liver, visceral/subcutaneous/bone marrow fat, muscle) using non-invasive advanced magnetic resonance spectroscopic (MRS) and imaging (MRI) methods.Methods: One subject participated in a 14-day PF under daily supervision of nurses and specialized physicians, ingesting a highly reduced intake: 200 Kcal/day coupled with active walking and drinking at least 3 L of liquids/day. The fasting was preceded by a 7-day pre-fasting vegetarian period and followed by 14 days of stepwise reintroduction of food. The longitudinal study collected imaging and biological data before the fast, at peak fasting, and 7 days, 1 month, and 4 months after re-feeding. Body fat mass in the trunk, abdomen, and thigh, liver and muscle mass, were respectively computed using advanced MRI and MRS signal modeling. Fat fraction, MRI relativity index T2* and susceptibility (Chi), as well as Fatty acid composition, were calculated at all-time points.Results: A decrease in body weight (BW: −9.5%), quadriceps muscle volume (−3.2%), Subcutaneous and Visceral Adipose Tissue (SAT −34.4%; VAT −20.8%), liver fat fraction (PDFF = 1.4 vs. 2.6 % at baseline) but increase in Spine Bone Marrow adipose tissue (BMAT) associated with a 10% increase in global adiposity fraction (PDFF: 54.4 vs. 50.9%) was observed. Femoral BMAT showed minimal changes compared to spinal level, with a slight decrease (−3.1%). Interestingly, fatty acid (FA) pattern changes differed depending on the AT locations. In muscle, all lipids increased after fasting, with a greater increase of intramyocellular lipid (IMCL: from 2.7 to 6.3 mmol/kg) after fasting compared to extramyocellular lipid (EMCL: from 6.2 to 9.5 mmol/kg) as well as Carnosine (6.9 to 8.1 mmol/kg). Heterogenous and reverse changes were also observed after re-feeding depending on the organ.Conclusion: These results suggest that investigating the effects of a 14-day PF intervention using advanced MRI and MRS is feasible. Quantitative MR indexes are a crucial adjunct to further understanding the effective changes in multiple crucial organs especially liver, spin, and muscle, differences between adipose tissue composition and the interplay that occurs during periodic fasting

Impact of obesity on global and regional systolic function in children: a CMR study

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Cardioprotective effects of shock wave therapy: A cardiac magnetic resonance imaging study on acute ischemia-reperfusion injury

IntroductionCardioprotection strategies remain a new frontier in treating acute myocardial infarction (AMI), aiming at further protect the myocardium from the ischemia-reperfusion damage. Therefore, we aimed at investigating the mechano-transduction effects induced by shock waves (SW) therapy at time of the ischemia reperfusion as a non-invasive cardioprotective innovative approach to trigger healing molecular mechanisms.MethodsWe evaluated the SW therapy effects in an open-chest pig ischemia-reperfusion (IR) model, with quantitative cardiac Magnetic Resonance (MR) imaging performed along the experiments at multiple time points (baseline (B), during ischemia (I), at early reperfusion (ER) (∼15 min), and late reperfusion (LR) (3 h)). AMI was obtained by a left anterior artery temporary occlusion (50 min) in 18 pigs (32 ± 1.9 kg) randomized into SW therapy and control groups. In the SW therapy group, treatment was started at the end of the ischemia period and extended during early reperfusion (600 + 1,200 shots @0.09 J/mm2, f = 5 Hz). The MR protocol included at all time points LV global function assessment, regional strain quantification, native T1 and T2 parametric mapping. Then, after contrast injection (gadolinium), we obtained late gadolinium imaging and extra-cellular volume (ECV) mapping. Before animal sacrifice, Evans blue dye was administrated after re-occlusion for area-at-risk sizing.ResultsDuring ischemia, LVEF decreased in both groups (25 ± 4.8% in controls (p = 0.031), 31.6 ± 3.2% in SW (p = 0.02). After reperfusion, left ventricular ejection fraction (LVEF) remained significantly decreased in controls (39.9 ± 4% at LR vs. 60 ± 5% at baseline (p = 0.02). In the SW group, LVEF increased quickly ER (43.7 ± 11.4% vs. 52.4 ± 8.2%), and further improved at LR (49.4 ± 10.1) (ER vs. LR p = 0.05), close to baseline reference (LR vs. B p = 0.92). Furthermore, there was no significant difference in myocardial relaxation time (i.e. edema) after reperfusion in the intervention group compared to the control group: ΔT1 (MI vs. remote) was increased by 23.2±% for SW vs. +25.2% for the controls, while ΔT2 (MI vs. remote) increased by +24.9% for SW vs. +21.7% for the control group.DiscussionIn conclusion, we showed in an ischemia-reperfusion open-chest swine model that SW therapy, when applied near the relief of 50′ LAD occlusion, led to a nearly immediate cardioprotective effect translating to a reduction in the acute ischemia-reperfusion lesion size and to a significant LV function improvement. These new and promising results related to the multi-targeted effects of SW therapy in IR injury need to be confirmed by further in-vivo studies in close chest models with longitudinal follow-up