Méthode de Relaxation Dynamique incrémentale

National audienceSee http://hal.archives-ouvertes.fr/docs/00/59/29/46/ANNEX/r_ZL662YL9.pd

Numerical study of dynamic relaxation with kinetic damping applied to inflatable fabric structures with extensions for 3D solid element and non-linear behavior

International audienceThis work mainly deals with the numerical study of inflatable fabric structures. As implicit integration schemes can lead to numerical difficulties such as singular stiffness matrices, explicit schemes are preferred. Since the final objective of this study is to obtain the final shape of a structure, a dynamic relaxation (DR) method is used. These methods allow us to obtain the final and stable shape of the inflatable fabric structures without doing so many time increments, which is the case when using a classical explicit integration method. Han and Lee [5] proposed an extension of the DR method stated by Barnes [13] suitable for triangular elements and elastic behavior. There are two main contributions in this paper. Firstly, we propose a modification of Han and Lee's method, allowing it to be used with any kind of membrane or solid finite elements and any reversible behavior. Secondly, we propose to rewrite the expression initially introduced by Barnes. Furthermore, these proposals are adapted for incremental loadings, allowing this way to obtain the pseudo-equilibriums of the intermediate phases. Numerical examples from academic problems (rectangular and circular membranes) show the efficiency and the reliability of proposed methods, with linear elasticity behavior, and also with a non-linear incremental behavior and finite deformation states

Stereotactic body radiation therapy for abdominal oligometastases: a biological and clinical review

Advances in imaging and biological targeting have led to the development of stereotactic body radiation therapy (SBRT) as an alternative treatment of extracranial oligometastases. New radiobiological concepts, such as ceramide-induced endothelial apoptosis after hypofractionated high-dose SBRT, and the identification of patients with oligometastatic disease by microRNA expression may yet lead to further developments. Key factors in SBRT are delivery of a high dose per fraction, proper patient positioning, target localisation, and management of breathing–related motion. Our review addresses the radiation doses and schedules used to treat liver, abdominal lymph node (LN) and adrenal gland oligometastases and treatment outcomes. Reported local control (LC) rates for liver and abdominal LN oligometastases are high (median 2-year actuarial LC: 61 -100% for liver oligometastases; 4-year actuarial LC: 68% in a study of abdominal LN oligometastases). Early toxicity is low-to-moderate; late adverse effects are rare. SBRT of adrenal gland oligometastases shows promising results in the case of isolated lesions. In conclusion, properly conducted SBRT procedures are a safe and effective treatment option for abdominal oligometastases

Cost-effectiveness of combination therapy umeclidinium/vilanterol versus tiotropium in symptomatic copd spanish patients

Purpose: Umeclidinium/vilanterol (UMEC/VI) is a novel fixed dose combination of a long-acting muscarinic receptor antagonist (LAMA) and a long-acting beta 2 receptor antagonist (LABA) agent. This analysis evaluated the incremental cost-effectiveness ratio (ICER) of UMEC/VI compared with tiotropium (TIO), from the Spanish National Health System (NHS) perspective. Methods: A previously published linked equations cohort model based on the epidemiological longitudinal study ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points) was used. Patients included were COPD patients with a post-bronchodilator forced expiratory volume in 1 second (FEV1) ≤70% and the presence of respiratory symptoms mea­sured with the modified Medical Research Council dyspnea scale (modified Medical Research Council ≥2). Treatment effect, expressed as change in FEV1 from baseline, was estimated from a 24-week head-to-head phase III clinical trial comparing once-daily UMEC/VI with once-daily TIO and was assumed to last 52 weeks following treatment initiation (maximum duration of UMEC/VI clinical trials). Spanish utility values were derived from a published local observa­tional study. Unitary health care costs (€2015) were obtained from local sources. A 3-year time horizon was selected, and 3% discount was applied to effects and costs. Results were expressed as cost/quality-adjusted life years (QALYs). Univariate and probabilistic sensitivity analysis (PSA) was performed. Results: UMEC/VI produced additional 0.03 QALY and €590 vs TIO, leading to an ICER of €21,475/QALY. According to PSA, the probability of UMEC/VI being cost-effective was 80.3% at a willingness-to-pay of €30,000/QALY. Conclusion: UMEC/VI could be considered as a cost-effective treatment alternative compared with TIO in symptomatic COPD patients from the Spanish NHS perspective

Simulation numérique de recherche de forme : application aux gilets de sauvetage gonflables

Cet article présente une application de la recherche de forme aux gilets de sauvetage gonflables. La recherche de forme est le nom générique désignant le processus de conception de la forme globale des structures légères instables telles que les structures gonflables. L'état d'équilibre statique des gilets gonflables est recherché pour analyser la forme générale, le volume contenu et la localisation des zones de plis. La méthode de relaxation dynamique avec amortissement cinétique permet d'éviter le problème de singularité de la matrice de raideur et le problème d'instabilité locale dans les zones de plis. Sa rapidité de convergence est très dépendante de la formulation de la matrice des masses. Dans cet article, plusieurs expressions des masses sont testées et leurs performances comparées entre elles

Plasma ceramide, a real-time predictive marker of pulmonary and hepatic metastases response to stereotactic body radiation therapy combined with irinotecan

AbstractBackground and purposesEarly biomarkers of tumour response are needed to discriminate between responders and non-responders to radiotherapy. We evaluated the ability of ceramide, a bioactive sphingolipid, to predict tumour sensitivity in patients treated by hypofractionated stereotactic body radiation therapy (SBRT) combined with irinotecan chemotherapy.Materials and methodsPlasma levels of total ceramide and of its subspecies were measured before and during treatment in 35 patients with liver and lung oligometastases of colorectal cancer included in a phase II trial. Cer levels were quantified by LC–ESI-MS/MS and compared to tumour volume response evaluated one year later by CT-scan.ResultsPretreatment plasma ceramide levels were not indicative of tumour response. Nevertheless, the levels of total ceramide and of its 4 main subspecies were significantly higher at days 3 and 10 of treatment in objective responders than in non-responders. According to Kaplan–Meier curves, almost complete tumour control was achieved at 1year in patients with increased total ceramide levels whereas 50% of patients with decreased levels experienced an increase in tumour volume.ConclusionsTotal plasma ceramide is a promising biomarker of tumour response to SBRT combined with irinotecan that should enable to segregate patients with high risk of tumour escape

Predictive Value of Skeletal Muscle Mass in Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma Patients Treated With Immune Checkpoint Inhibitors

Background Reduced muscle mass has been associated with increased treatment complications in several tumor types. We evaluated the impact of skeletal muscle index (SMI) on prognosis and immune-related adverse events (IrAEs) in a cohort of recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) treated with immune checkpoints inhibitors (ICI). Methods A single-institutional, retrospective study was performed including 61 consecutive patients of R/M HNSCC diagnosed between July 2015 and December 2018. SMI was quantified using a CT scan at L3 to evaluate body composition. Median baseline SMI was used to dichotomize patients in low and high SMI. Kaplan-Meier estimations were used to detect overall survival (OS) and progression-free survival (PFS). Toxicity was recorded using Common Terminology Criteria for Adverse Event v4.3. Results Patients were 52 men (85.2%) with mean of age 57.7 years (SD 9.62), mainly oral cavity (n = 21; 34.4%). Low SMI was an independent factor for OS in the univariate (HR, 2.06; 95% CI, 1.14-3.73, p = 0.017) and multivariate Cox analyses (HR, 2.99; 95% CI, 1.29-6.94; p = 0.011). PFS was also reduced in patients with low SMI (PFS HR, 1.84; 95% CI, 1.08-3.12; p = 0.025). IrAEs occurred in 29 (47.5%) patients. There was no association between low SMI and IrAEs at any grade (OR, 0.56; 95% CI, 0.20-1.54; p = 0.261). However, grades 3 to 4 IrAEs were developed in seven patients of whom three had low SMI. Conclusions Low SMI before ICI treatment in R/M HNSCC patients had a negative impact on OS and PFS. Further prospective research is needed to confirm the role of body composition as a predictive biomarker in ICI treatment