Non Linearity of the Ball/Rubber Impact in Table Tennis: Experiments and Modeling

AbstractAlong with comfort, the speed is a key metric used to qualify the performance of a table tennis racket. The restitution coefficient which corresponds to the ratio between the velocities of the ball right before and after normally impacting the racket relates to the speed performance: the higher the restitution coefficient, the greater the speed. Thus, understanding the normal impact problem is key and suggests investigating the effects of the intrinsic properties and architectures of the constituents of the racket. In this work, both experimental and numerical studies were pursued. Experimentally, normal impact tests were performed for varying launching velocities on samples made of isolated or associated constituents of a table tennis racket and the restitution coefficients calculated. Numerically, 3D finite elements simulations were conducted to replicate the normal impact conditions while incorporating the time-dependent constitutive behavior of the polymeric elements contributing during the impact: the racket constituents (the foam and the compact) and the ball. The restitution coefficients are seen to decrease with increasing launching velocity, while being minimum when the two racket polymeric constituents are associated. A fair agreement is obtained with the FE simulations in which the sample/ball contact zone is identified as a ring with its mean radius increasing till the maximum crushing. Ultimately, additional FE calculations confirm that the friction plays a key role in the energy dissipation process, alongside with the rate-dependent behavior and architecture of the polymeric constituents

Reverse pre-symptomatic testing for Huntington disease: double disclosure when 25% at-risk children reveal the genetic status to their parent

International audiencePredictive testing for Huntington disease (HD) in 25% at-risk individuals is testing with full knowledge, and sometimes assuming, that the parent does not want to know his status. The goal of this study was to understand: (1) the differences in the motivation between 25% and 50% at-risk individuals to be tested and (2) the consequences of “double disclosure”, including parental reactions. Test requests from 25% at-risk individuals were rare (155/1611, 10%). We compared their motivation with those of 1456 50% at-risk individuals. The principal motivation to have the test for both groups was “to know” (48% versus 58%, p = 0.049), but the desire to have children was more frequent in the 25% at-risk group (32% versus 17%, p < 0.001). Sixty percent of the 25% at-risk group went through the testing procedure: 15% (n = 14) were variant positive for HD. Testees reported four adverse reactions of their parent (22%): one committed suicide and three became depressed. This result highlights the impact of “double disclosure”, a bad result for the person themselves and the transmitting parent. It is the responsibility of the team to anticipate this outcome with the 25% at-risk individuals: children revealing the genetic status to their parent. They should help the testees and their family to find a satisfactory solution to help prevent adverse reactions. This includes ensuring that the candidate is well-infomed abour the testing options and consequences to her/himself but also to her/his parent. The at-risk parent should be offered to discuss the implications of their child’s testing

Matériaux architecturés à base polymère : Etude des composants polymériques d’une raquette de ping-pong

National audienceEn plus du bois, une raquette de tennis de table se compose d’un revêtement en élastomères qui associe une mousse et un compact formés de picots que viendra impacter la balle en condition de jeu. Les performances globales de la raquette sont décrites (ressenties) par les professionnels de la discipline en termes de « contrôle » et de « rapidité » et la compréhension du rôle du revêtement reste limitée. Aussi, cette étude se concentre sur l’influence des constituants polymériques du revêtement. La seule performance « rapidité » est ici considérée et se quantifie en termes de coefficient de restitution CR, ratio entre les vitesses incidente et réfléchie de la balle impactant un support sous incidence normale. Mesures expérimentales et modélisation par Eléments Finis sont effectuées et confrontées de manière. Les calculs E.F. montrent que le frottement entre la balle et le support représente une contribution non négligeable à la dissipation totale d’énergie (responsable de la diminution du CR), au même titre que l’amortissement interne des composants polymériques, balle comprise

Oligo-astrocytoma in LZTR1-related Noonan syndrome

International audienceMutations in LZTR1, already known to be causal in familial schwannomatosis type 2, have been recently involved in a small proportion of patients with autosomal dominant and autosomal recessive Noonan syndrome. LZTR1 is also a driver gene in non syndromal glioblastoma. We report a 26-year-old patient with typical Noonan syndrome, and the dominantly transmitted c.850C > T (p.(Arg284Cys)) variant in LZTR1. An oligoastrocytoma was diagnosed in the patient at the age of 22 years; recurrence of the tumor occurred at age 26, as a ganglioblastoma. The patient had been transiently treated with growth hormone between ages 15 and 17. Considering the implication of LZTR1 in sporadic tumors of the nervous system, we hypothesize that gliomas are a possible complication of LZTR1-related Noonan syndrome. This report also supports a possible link between occurrence of a cerebral tumor in Noonan syndrome and a previous treatment with growth hormone

Assessment of DNA integrity of Palaemonidae spermatozoa using the alkaline Comet assay: a pertinent tools for environmental biomonitoring

International audienceThe aim of this study was to adapt the comet assay in spermatozoa of the marine prawn Palaemon serratus to use it as a marker of sperm quality. Indeed, due to the characteristics of their spermatozoa, the measurement of DNA integrity is ones of the few markers, which can be transferred to crustaceans to assess the quality of their semen. In first time, the methods to collect and to maintain spermatozoa were optimized. The cell survival was estimated during kinetics of preservation (i.e. 1, 2, 4 and 8 h) in various suspension media to define the artificial seawater (ASW) as optimal. Several methods in the releasing of spermatozoa from the spermatophore of prawns were estimated with regard to their incidence both on the efficiency of extraction and the survival of cells. The pipetting up and down turned out to be the most successful and the least invasive technic. Secondly, the transfer of Comet assay was optimized by studying various times in both cell lysis (i.e. 1, 6, 18 h) and DNA denaturation (i.e. 15, 30 and 45 min), after in vitro exposure of spermatozoa toward a H2O2gradient as model genotoxicant. Results revealed that a minimum of 1 h in cell lysis and 15 min of DNA denaturation was sufficient to obtain valuable results, linked with a low compaction of DNA in spermatozoa of Palaemon sp. Finally, the sensitivity of P. serratus spermatozoa was assessed after in vitro exposures toward model genotoxicants displaying various modes of interaction with DNA (i.e. UV-C, 5-30 sec; H2O2, 5-10 μM and MMS, 0.5-5 mM) and some environmental contaminants known or suspected to be genotoxic (i.e. cadmium and diuron, 0.015-1.5 μg.L-1; carbamazepine, 0.1-10 μg.L-1) toward invertebrates. The low variability of the baseline level of DNA strand breaks recorded in controls highlighted the robustness of the method. P. serratus spermatozoa displayed significant DNA damage from the lowest doses tested for all model genotoxicants, but conversely, no genotoxic effect of tested environmental contaminants was observed. These results could suggest a difference in the response or sensitivity of spermatozoa to environmental genotoxicity between invertebrate species, and therefore the interest of Palaemonidae prawns in ecogenotoxicology. In conclusion, the present study underlines the potential of the Comet assay as a marker to assess the contamination impact on the sperm quality in Palaemonidae prawns in view to a potential application for in situ biomonitoring surveys

Bioaccumulation of Toxoplasma and Cryptosporidium by the freshwater crustacean Gammarus fossarum: Involvement in biomonitoring surveys and trophic transfer

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Homozygous MFN2 variants causing severe antenatal encephalopathy with clumped mitochondria

International audiencePathogenic variants in the MFN2 gene are commonly associated with autosomal dominant (CMT2A2A) or recessive (CMT2A2B) Charcot-Marie-Tooth disease, with possible involvement of the CNS. Here, we present a case of severe antenatal encephalopathy with lissencephaly, polymicrogyria and cerebellar atrophy. Whole genome analysis revealed a homozygous deletion c.1717-274_1734 del (NM_014874.4) in the MFN2 gene, leading to exon 16 skipping and in-frame loss of 50 amino acids (p.Gln574_Val624del), removing the proline-rich domain and the transmembrane domain 1 (TM1). MFN2 is a transmembrane GTPase located on the mitochondrial outer membrane that contributes to mitochondrial fusion, shaping large mitochondrial networks within cells. In silico modelling showed that the loss of the TM1 domain resulted in a drastically altered topological insertion of the protein in the mitochondrial outer membrane. Fetus fibroblasts, investigated by fluorescent cell imaging, electron microscopy and time-lapse recording, showed a sharp alteration of the mitochondrial network, with clumped mitochondria and clusters of tethered mitochondria unable to fuse. Multiple deficiencies of respiratory chain complexes with severe impairment of complex I were also evidenced in patient fibroblasts, without involvement of mitochondrial DNA instability. This is the first reported case of a severe developmental defect due to MFN2 deficiency with clumped mitochondria

Interest of a multispecies approach in active biomonitoring: Application in the Meuse watershed

International audienceA biomonitoring approach based on a single model species cannot be representative of the contaminations impacts on the ecosystem overall. As part of the Interreg DIADeM program (“Development of an integrated approach for the diagnosis of the water quality of the River Meuse”), a study was conducted to establish the proof of concept that the use of a multispecies active biomonitoring approach improves diagnostic of aquatic systems. The complementarity of the biomarker responses was tested in four model species belonging to various ecological compartments: the bryophyte Fontinalis antipyretica, the bivalve Dreissena polymorpha, the amphipod Gammarus fossarum and the fish Gasterosteus aculeatus. The species have been caged upstream and downstream from five wastewater treatment plants (WWTPs) in the Meuse watershed. After the exposure, a battery of biomarkers was measured and results were compiled in an Integrated Biomarker Response (IBR) for each species. A multispecies IBR value was then proposed to assess the quality of the receiving environment upstream the WWTPs. The effluent toxicity was variable according to the caged species and the WWTP. However, the calculated IBR were high for all species and upstream sites, suggesting that the water quality was already downgraded upstream the WWTP. This contamination of the receiving environment was confirmed by the multispecies IBR which has allowed to rank the rivers from the less to the most contaminated. This study has demonstrated the interest of the IBR in the assessment of biological impacts of a point-source contamination (WWTP effluent) but also of the receiving environment, thanks to the use of independent references. Moreover, this study has highlighted the complementarity between the different species and has emphasized the interest of this multispecies approach to consider the variability of the species exposition pathway and sensibility as well as the mechanism of contaminants toxicity in the final diagnosis