Head Impact Situations in Professional Football (Soccer)

To assess head impact incidents (HIIs) and to distinguish diagnosed head injuries from other incidents, a video observation analysis of match HIIs was conducted in the German Bundesliga (2017/18 season). Video recordings of each match were screened to identify the respective events. Head injury data were identified by a prospective injury registry. HII and head injury incidence rates (IR) were calculated with 95 % CIs. The total number of HIIs was 1362 corresponding to an IR of 134.9/1000 match hours (95% CI 127.9–142.2). In 123 HII (IR 12.2, 95% CI 10.2–14.5) the contact was classified as severe. Head contact with the opponent was the most frequent cause (85%). The most frequent mechanism was in 44% (combined) the arm and elbow-to-head, followed by head-to-head and hand-to-head contacts (each 13%). In 58%, the HIIs occurred during header duels. Twenty-nine head injuries were recorded (IR 2.9, 95% CI 2.0–4.1). Concussions/traumatic brain injuries accounted for 48%, head/facial fractures 24%, head/facial contusions 21%, and lacerations/abrasions 7%. The number of HIIs not classified as concussions/more severe trauma was high. Identification of HIIs and head injury severity should be improved during on-field assessment as many head injuries might go unrecognised based on the large number of HIIs

Mesoscopic effects in tunneling between parallel quantum wires

We consider a phase-coherent system of two parallel quantum wires that are coupled via a tunneling barrier of finite length. The usual perturbative treatment of tunneling fails in this case, even in the diffusive limit, once the length L of the coupling region exceeds a characteristic length scale L_t set by tunneling. Exact solution of the scattering problem posed by the extended tunneling barrier allows us to compute tunneling conductances as a function of applied voltage and magnetic field. We take into account charging effects in the quantum wires due to applied voltages and find that these are important for 1D-to-1D tunneling transport.Comment: 8 pages, 7 figures, improved Figs., added Refs. and appendix, to appear in Phys. Rev.

Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci

Background: A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs). Results: We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an `autosomal Barr body' with less compacted chromatin and incomplete RNAP II exclusion. Conclusions: 3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform compaction of the Barr body at the nucleosome level. The localization of distinct Xist RNA foci at boundaries of the rudimentary ANC may be considered as snap-shots of a dynamic interaction with silenced genes. Enrichment of SAF-A within Xi territories and its close spatial association with Xist RNA suggests their cooperative function for structural organization of Xi

Three-dimensional super-resolution microscopy of the inactive X chromosome territory reveals a collapse of its active nuclear compartment harboring distinct Xist RNA foci

Background: A Xist RNA decorated Barr body is the structural hallmark of the compacted inactive X territory in female mammals. Using super resolution three-dimensional structured illumination microscopy (3D-SIM) and quantitative image analysis, we compared its ultrastructure with active chromosome territories (CTs) in human and mouse somatic cells, and explored the spatio-temporal process of Barr body formation at onset of inactivation in early differentiating mouse embryonic stem cells (ESCs). Results: We demonstrate that all CTs are composed of structurally linked chromatin domain clusters (CDCs). In active CTs the periphery of CDCs harbors low-density chromatin enriched with transcriptionally competent markers, called the perichromatin region (PR). The PR borders on a contiguous channel system, the interchromatin compartment (IC), which starts at nuclear pores and pervades CTs. We propose that the PR and macromolecular complexes in IC channels together form the transcriptionally permissive active nuclear compartment (ANC). The Barr body differs from active CTs by a partially collapsed ANC with CDCs coming significantly closer together, although a rudimentary IC channel system connected to nuclear pores is maintained. Distinct Xist RNA foci, closely adjacent to the nuclear matrix scaffold attachment factor-A (SAF-A) localize throughout Xi along the rudimentary ANC. In early differentiating ESCs initial Xist RNA spreading precedes Barr body formation, which occurs concurrent with the subsequent exclusion of RNA polymerase II (RNAP II). Induction of a transgenic autosomal Xist RNA in a male ESC triggers the formation of an `autosomal Barr body' with less compacted chromatin and incomplete RNAP II exclusion. Conclusions: 3D-SIM provides experimental evidence for profound differences between the functional architecture of transcriptionally active CTs and the Barr body. Basic structural features of CT organization such as CDCs and IC channels are however still recognized, arguing against a uniform compaction of the Barr body at the nucleosome level. The localization of distinct Xist RNA foci at boundaries of the rudimentary ANC may be considered as snap-shots of a dynamic interaction with silenced genes. Enrichment of SAF-A within Xi territories and its close spatial association with Xist RNA suggests their cooperative function for structural organization of Xi

Anchoring a Leviathan: How the Nuclear Membrane Tethers the Genome

It is well established that the nuclear envelope has many distinct direct connections to chromatin that contribute to genome organization. The functional consequences of genome organization on gene regulation are less clear. Even less understood is how interactions of lamins and nuclear envelope transmembrane proteins (NETs) with chromatin can produce anchoring tethers that can withstand the physical forces of and on the genome. Chromosomes are the largest molecules in the cell, making megadalton protein structures like the nuclear pore complexes and ribosomes seem small by comparison. Thus to withstand strong forces from chromosome dynamics an anchoring tether is likely to be much more complex than a single protein-protein or protein-DNA interaction. Here we will briefly review known NE-genome interactions that likely contribute to spatial genome organization, postulate in the context of experimental data how these anchoring tethers contribute to gene regulation, and posit several hypotheses for the physical nature of these tethers that need to be investigated experimentally. Significantly, disruption of these anchoring tethers and the subsequent consequences for gene regulation could explain how mutations in nuclear envelope proteins cause diseases ranging from muscular dystrophy to lipodystrophy to premature ageing progeroid syndromes. The two favored hypotheses for nuclear envelope protein involvement in disease are 1) weakening nuclear and cellular mechanical stability, and 2) disrupting genome organization and gene regulation. Considerable experimental support has been obtained for both. The integration of both mechanical and gene expression defects in the disruption of anchoring tethers could provide a unifying hypothesis consistent with both

Franchissement du torrent des Bossons par la route d’accès à Chamonix et au tunnel du Mont-Blanc

Le torrent des Bossons, affluent de rive gauche de l’Arve à l’aval de Chamonix, est issu d’un appareil glaciaire complexe dominé par le Mont Blanc, qui implique des risques d’apports de matériaux et de crues violentes spécifiquement dus au régime glaciaire, et particulièrement intenses. Ces risques, qui se sont historiquement manifestés à de nombreuses reprises, liés notamment aux fluctuations du glacier des Bossons, ont été très amplifiés récemment par le recul important du front glaciaire, et par l’augmentation de la vulnérabilité due à l’urbanisation croissante des zones riveraines. A l’occasion de la rectification de la Route Nationale n° 205, voie essentielle d’accès à Chamonix et au Tunnel du Mont Blanc, la nécessité de modifier le franchissement du torrent, a justifié une analyse précise de ces risques, et a abouti à la conception d’une solution originale d’ouvrage, mise au point au moyen d’un modèle réduit physique

Protection du village du Tour contre le glissement des Posettes à l’amont de la vallée de Chamonix Mont-Blanc (maître d’ouvrage Syndicat mixte d’Aménagement de l’Arve et de ses Affluents)

A l’amont de Chamonix, le glissement des Posettes qui affecte le versant de rive droite de l’Arve, à l’origine de son bassin versant (5 km²), concerne 2 Mm³ environ, sapés en pied par le torrent de l’Arve. Ce glissement et les apports qui en résultent par l’Arve : - menacent le village du Tour immédiatement à l’aval, - engravent et exhaussent le lit de l’Arve jusqu’à Chamonix, - colmatent tout le lit de l’Arve jusqu’à Genève (100 km). La solution retenue consiste à réaliser : - une dérivation souterraine du torrent sur 800 m de longueur, pour supprimer l’action de sape du torrent, - une plage de rétention et de laminage des apports solides potentiels, - une amélioration de la capacité d’évacuation du lit de l’Arve. La mise au point et le dimensionnement des ouvrages ont été étudiés au moyen de deux modèles réduits et les chantiers de réalisation sont actuellement en cours

Le risque d’éboulement des ruines de Séchilienne Étude des modalités de rupture du barrage naturel sur modèle physique

Le versant du mont Sec au lieu dit des ”ruines de Séchilienne” est instable. Des blocs sont susceptibles de tomber. C’est pourquoi de nombreux capteurs surveillent en continu les déplacements de ce versant de montagne. Les experts estiment aujourd’hui qu’il est possible qu’un volume total de l’ordre de trois millions de mètres cubes de matériaux s’éboulent dans les trente à cinquante prochaines années. Dans le pire des cas, il est possible qu’un barrage naturel barre la vallée et donc le cours de la Romanche, d’une hauteur de l’ordre de 6m. Que se passerait-il en cas de crue de la Romanche ? Si le barrage naturel se rompait brusquement, une onde de crue se propagerait rapidement dans la vallée. Pour prévenir ce scénario catastrophe, les premières études de faisabilité prévoyaient la construction de « parades hydrauliques » constituées de casiers et de digues, pour un montant de travaux de plusieurs millions d’Euros. La détermination du débit sortant du barrage naturel est un enjeu majeur pour le choix des parades hydrauliques à adopter. Devant la complexité du phénomène de rupture du barrage naturel, les modélisations mathématiques nécessitent de prendre beaucoup trop d’hypothèses pour obtenir un résultat fiable. Seule une modélisation sur un modèle réduit physique permet de lever ces incertitudes. C’est pourquoi le Syndicat Mixte des Bassins Hydrauliques de l’Isère (Symbhi 38) a décidé de confier une étude sur modèle physique à la CNR. Le modèle respecte les règles classiques de similitude de Froude et de transport solide. Trente essais ont été réalisés pour encadrer tous les scénarios possibles et ont permis de paramétrer une loi d’érosion du barrage naturel

Le franchissement des vallées de l'Isle et de la Dordogne par l'autoroute A89 près de Libourne

Le projet d'implantation de l'autoroute A89 dans les plaines inondables de l'Isle et la Dordogne, prés de Libourne, a nécessité la mise en œuvre d'outils de simulation performants. Un modèle réduit physique de grande dimension (près de 3 000 m²), associé à un modèle numérique bidimensionnel, ont permis d'optimiser les ouvrages en respectant toutes les contraintes réglementaires de transparence hydraulique vis-à-vis de l'écoulement des crues de toutes natures. Le modèle réduit physique s'est également révélé être un outil de communication fondamental vis-à-vis des riverains et différents acteurs du bassin

Spatial separation of Xist RNA and polycomb proteins revealed by superresolution microscopy

In female mammals, one of the two X chromosomes is transcriptionally silenced to equalize X-linked gene dosage relative to XY males, a process termed X chromosome inactivation. Mechanistically, this is thought to occur via directed recruitment of chromatin modifying factors by the master regulator, X-inactive specific transcript (Xist) RNA, which localizes in cis along the entire length of the chromosome. A well-studied example is the recruitment of polycomb repressive complex 2 (PRC2), for which there is evidence of a direct interaction involving the PRC2 proteins Enhancer of zeste 2 (Ezh2) and Supressor of zeste 12 (Suz12) and the A-repeat region located at the 5′ end of Xist RNA. In this study, we have analyzed Xist-mediated recruitment of PRC2 using two approaches, microarray-based epigenomic mapping and superresolution 3D structured illumination microscopy. Making use of an ES cell line carrying an inducible Xist transgene located on mouse chromosome 17, we show that 24 h after synchronous induction of Xist expression, acquired PRC2 binding sites map predominantly to gene-rich regions, notably within gene bodies. Paradoxically, these new sites of PRC2 deposition do not correlate with Xist-mediated gene silencing. The 3D structured illumination microscopy was performed to assess the relative localization of PRC2 proteins and Xist RNA. Unexpectedly, we observed significant spatial separation and absence of colocalization both in the inducible Xist transgene ES cell line and in normal XX somatic cells. Our observations argue against direct interaction between Xist RNA and PRC2 proteins and, as such, prompt a reappraisal of the mechanism for PRC2 recruitment in X chromosome inactivation