472 research outputs found
Prodsimplicial-Neighborly Polytopes
Simultaneously generalizing both neighborly and neighborly cubical polytopes,
we introduce PSN polytopes: their k-skeleton is combinatorially equivalent to
that of a product of r simplices. We construct PSN polytopes by three different
methods, the most versatile of which is an extension of Sanyal and Ziegler's
"projecting deformed products" construction to products of arbitrary simple
polytopes. For general r and k, the lowest dimension we achieve is 2k+r+1.
Using topological obstructions similar to those introduced by Sanyal to bound
the number of vertices of Minkowski sums, we show that this dimension is
minimal if we additionally require that the PSN polytope is obtained as a
projection of a polytope that is combinatorially equivalent to the product of r
simplices, when the dimensions of these simplices are all large compared to k.Comment: 28 pages, 9 figures; minor correction
The congested International Match Calendar in football : views of 1055 professional male players
BACKGROUND : The International Match Calendar congestion affects players recovery. The views of a worldwide cohort of professional football players is shared in this communication.
METHODS : A cross-sectional observational study recruited players through FĂ©dĂ©ration Internationale des Associations de Footballeurs Professionnelâs national members. An electronic survey was shared in English, French, Italian and Spanish with 1055 players consenting and completing it anonymously in November 2021.
RESULTS : A total of 42% of respondents believe back-to-back matches should be limited to three. Most respondents (69%) felt off or in season breaks are infringed by clubs or national teams and 83% believe regulations should protect them. A total of 55% of players believed they sustained one or more injuries due to the overload and it has affected 52% of respondentsâ mental state.
CONCLUSION : The congested International Match Calendar poses a risk to professional footballers physical and mental health. Poor recovery between matches may affect player availability and performance. Players should be represented by active players when International Match Calendar scheduling decisions are made. Administrators should seek medical guidance regarding the effects of overload on performance prior to making decisions. This study allows the opportunity for a larger national team player sample to be studied.https://bmcsportsscimedrehabil.biomedcentral.comhj2023Sports Medicin
Bose-Einstein Condensate in Weak 3d Isotropic Speckle Disorder
The effect of a weak three-dimensional (3d) isotropic laser speckle disorder
on various thermodynamic properties of a dilute Bose gas is considered at zero
temperature. First, we summarize the derivation of the autocorrelation function
of laser speckles in 1d and 2d following the seminal work of Goodman. The goal
of this discussion is to show that a Gaussian approximation of this function,
proposed in some recent papers, is inconsistent with the general background of
laser speckle theory. Then we propose a possible experimental realization for
an isotropic 3d laser speckle potential and derive its corresponding
autocorrelation function. Using a Fourier transform of that function, we
calculate both condensate depletion and sound velocity of a Bose-Einstein
condensate as disorder ensemble averages of such a weak laser speckle potential
within a perturbative solution of the Gross-Pitaevskii equation. By doing so,
we reproduce the expression of the normalfluid density obtained earlier within
the treatment of Landau. This physically transparent derivation shows that
condensate particles, which are scattered by disorder, form a gas of
quasiparticles which is responsible for the normalfluid component
Osteoarthritic changes in the knees of recently retired male professional footballers : a pilot study
BACKGROUND: Knee osteoarthritis (OA) is common amongst retired male professional footballers. There is limited understanding with respect to the interplay between imaging findings, clinical presentation and patient-reported outcome measures (PROMs) in retired professional footballers with knee OA. OBJECTIVES: This pilot study aimed to evaluate the extent of radiological and clinical knee OA in a cohort of retired male professional footballers, and to explore the relationship between these findings and knee-related PROMs. METHODS: Fifteen retired male professional footballers underwent knee radiographs and were surveyed on their history of clinical OA, severe knee injury and previous knee surgery. The Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS) and the Patient-Reported Outcomes Measurement Information System Global Health (PROMIS-GH) were used to assess health outcomes, such as level of function and pain. RESULTS: Radiological knee OA was diagnosed in six out of 15 participants. Seven of the participants had a clinical diagnosis of knee OA. Evidence of clinical and radiological OA was present amongst four participants. Radiological knee OA and clinical OA was significantly associated with a history of severe knee injury and previous knee surgery. Low correlations (Ï<-0.40) were found between knee OA severity and knee-related PROMs. Moderate correlation (Ï=-0.65) was found between clinical knee OA and KOOS-SP. CONCLUSION: Clinical knee OA correlates with PROMs amongst retired professional footballers but radiological OA does not. Further studies are required to understand the relationship between imaging findings, clinical presentation and PROMs amongst retired professional footballers with knee OA.https://journals.assaf.org.za/index.php/sajsmdm2022Sports Medicin
Multi-triangulations as complexes of star polygons
Maximal -crossing-free graphs on a planar point set in convex
position, that is, -triangulations, have received attention in recent
literature, with motivation coming from several interpretations of them.
We introduce a new way of looking at -triangulations, namely as complexes
of star polygons. With this tool we give new, direct, proofs of the fundamental
properties of -triangulations, as well as some new results. This
interpretation also opens-up new avenues of research, that we briefly explore
in the last section.Comment: 40 pages, 24 figures; added references, update Section
Hemodynamic-informed parcellation of fMRI data in a Joint Detection Estimation framework
International audienceIdentifying brain hemodynamics in event-related functional MRI (fMRI) data is a crucial issue to disentangle the vascular response from the neuronal activity in the BOLD signal. This question is usually addressed by estimating the so-called Hemodynamic Response Function (HRF). Voxelwise or region-/parcelwise inference schemes have been proposed to achieve this goal but so far all known contributions commit to pre-specified spatial supports for the hemodynamic territories by defining these supports either as individual voxels or a priori fixed brain parcels. In this paper, we introduce a Joint Parcellation-Detection-Estimation (JPDE) procedure that incorporates an adaptive parcel identification step based upon local hemodynamic properties. Efficient inference of both evoked activity, HRF shapes and supports is then achieved using variational approximations. Validation on synthetic and real fMRI data demonstrate the JPDE performance over standard detection estimation schemes and suggest it as a new brain exploration tool
Modelling the bimodal distribution of indoor gamma-ray dose-rates in Great Britain
Gamma radiation from naturally occurring sources (including directly ionizing cosmic-rays) is a major component of background radiation. An understanding of the magnitude and variation of doses from these sources is important, and the ability to predict them is required for epidemiological studies. In the present paper, indoor measurements of naturally occurring gamma-rays at representative locations in Great Britain are summarized. It is shown that, although the individual measurement data appear unimodal, the distribution of gamma-ray dose-rates when averaged over relatively small areas, which probably better represents the underlying distribution with inter-house variation reduced, appears bimodal. The dose-rate distributions predicted by three empirical and geostatistical models are also bimodal and compatible with the distributions of the areally averaged dose-rates. The distribution of indoor gamma-ray dose-rates in the UK is compared with those in other countries, which also tend to appear bimodal (or possibly multimodal). The variation of indoor gamma-ray dose-rates with geology, socio-economic status of the area, building type, and period of construction are explored. The factors affecting indoor dose-rates from background gamma radiation are complex and frequently intertwined, but geology, period of construction, and socio-economic status are influential; the first is potentially most influential, perhaps, because it can be used as a general proxy for local building materials. Various statistical models are tested for predicting indoor gamma-ray dose-rates at unmeasured locations. Significant improvements over previous modelling are reported. The dose-rate estimates generated by these models reflect the imputed underlying distribution of dose-rates and provide acceptable predictions at geographical locations without measurements
Virtual Compton Scattering and Neutral Pion Electroproduction in the Resonance Region up to the Deep Inelastic Region at Backward Angles
We have made the first measurements of the virtual Compton scattering (VCS)
process via the H exclusive reaction in the nucleon resonance
region, at backward angles. Results are presented for the -dependence at
fixed GeV, and for the -dependence at fixed near 1.5 GeV.
The VCS data show resonant structures in the first and second resonance
regions. The observed -dependence is smooth. The measured ratio of
H to H cross sections emphasizes the different
sensitivity of these two reactions to the various nucleon resonances. Finally,
when compared to Real Compton Scattering (RCS) at high energy and large angles,
our VCS data at the highest (1.8-1.9 GeV) show a striking -
independence, which may suggest a transition to a perturbative scattering
mechanism at the quark level.Comment: 20 pages, 8 figures. To appear in Phys.Rev.
Mise Ă jour des recommandations du GEFPICS pour lâĂ©valuation du statut HER2 dans les cancers du sein en France
En Europe, les patientes atteintes dâun cancer du sein invasif susceptibles de recevoir un traitement ciblĂ© anti-HER2 sont actuellement sĂ©lectionnĂ©es sur la base dâun test immunohistochimique (IHC). Les techniques dâhybridation in situ (HIS) doivent ĂȘtre utilisĂ©es pour lâĂ©valuation des cas IHC ambigus (2+) et pour lâĂ©talonnage de la technique IHC. Les patientes Ă©ligibles au traitement ciblant HER2 prĂ©sentent un statut HER2 positif dĂ©fini par un test IHC 3+ ou un test 2+ amplifiĂ©. Une dĂ©tection correcte du statut HER2 est indispensable Ă une utilisation optimale des thĂ©rapeutiques ciblĂ©es puisque leur efficacitĂ© est limitĂ©e aux patientes surexprimant HER2. Il est capital que lâĂ©valuation du statut HER2 soit optimisĂ©e et fiable. Ces recommandations du groupe dâĂ©tude des facteurs pronostiques IHC dans le cancer du sein (GEFPICS) dĂ©taillent et commentent les diffĂ©rentes Ă©tapes des techniques IHC et HIS, les contrĂŽles utilisables et les rĂšgles gĂ©nĂ©rales de lâapprentissage de la lecture. Une fois acquis, ce savoir-faire doit ĂȘtre pĂ©rennisĂ© par lâobservation de rĂšgles de bonnes pratiques techniques (utilisation rigoureuse de tĂ©moins internes et externes et participation rĂ©guliĂšre Ă des programmes dâAssurance qualitĂ© [AQ])., Summary In Europe, patients who may benefit from an HER2 targeted drug are currently selected by immunohistochemistry (IHC). In situ hybridization (ISH) techniques should be used for complementary assessment of ambiguous 2+ IHC cases and for the calibration of the IHC technique. Eligibility to an HER2 target treatment is defined by an HER2 positive status being IHC test 3+ or 2+ amplified. Reliable detection of HER2 status is essential to the appropriate usage of HER2 targeted drugs because its specificity is limited to tumors overexpressing HER2. It is essential that the IHC evaluation of the HER2 status of a mammary carcinoma is optimized and reliable. This GEFPICSâ guidelines look over the different steps of the IHC technique, the controls and, the rules for interpretation. Once acquired, this knowledge must be perpetuated by the observation of rules of good technical practice (internal and external controls, quality assurance programs)
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