79 research outputs found

    A finite analog of the AGT relation I: finite W-algebras and quasimaps' spaces

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    Recently Alday, Gaiotto and Tachikawa proposed a conjecture relating 4-dimensional super-symmetric gauge theory for a gauge group G with certain 2-dimensional conformal field theory. This conjecture implies the existence of certain structures on the (equivariant) intersection cohomology of the Uhlenbeck partial compactification of the moduli space of framed G-bundles on P^2. More precisely, it predicts the existence of an action of the corresponding W-algebra on the above cohomology, satisfying certain properties. We propose a "finite analog" of the (above corollary of the) AGT conjecture. Namely, we replace the Uhlenbeck space with the space of based quasi-maps from P^1 to any partial flag variety G/P of G and conjecture that its equivariant intersection cohomology carries an action of the finite W-algebra U(g,e) associated with the principal nilpotent element in the Lie algebra of the Levi subgroup of P; this action is expected to satisfy some list of natural properties. This conjecture generalizes the main result of arXiv:math/0401409 when P is the Borel subgroup. We prove our conjecture for G=GL(N), using the works of Brundan and Kleshchev interpreting the algebra U(g,e) in terms of certain shifted Yangians.Comment: minor change

    Estimation of the number of seriously injured road users in France, 2006-2015

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    European Congress of Epidemiology, LYON, FRANCE, 04-/07/2018 - 06/07/2018Background The European Commission requests its member states to provide the number of serious road injuries, according to MAIS 3+=Maximum AIS 3+, where AIS=Abbreviated Injury Scale. This challenges in all countries the issue of under-reporting of road injuries in the official police data and the issue of using a medical trauma scale. Methods In France, as in most countries, police data provide the frequency of road casualties, but they suffer from large under-reporting and strong selection bias (on severity, mode of transport, etc). In the Rhone county (pop 1.6M inhabitants). Other data are available: a road trauma registry has been set up in 1996. It covers fatalities, hospitalized, and those attending the Emergency departments only. All injuries are directly coded into the Abbreviated Injury Scale, by the registry physician. At the Rhône county level, both databases are linked. Annually, on the 2006-2012 period, the police reports 2800 casualties, the road trauma registry 7400 by the registry and 1700 are identified as common to both sources. A capture-recapture approach is then used, so that we can estimate the real number of road casualties (in the Rhône). More importantly the corrections factors between the police data and the estimated real subgroup of road causalities in the Rhône. In particular, to account for some conditions for applying capture-recapture, a multivariate model is used, including the variables that are associated with lower probability of reporting by the police: type of police, road network, severity measured by hospitalised (yes/no), MAIS3+, road user type (pedestrian, cyclist, car occupant...), whether the crash involved a crash opponent or not, etc. The police correction factors are finally applied to the national police data with the assumption that police recording practices are rather homogenous across France, by type of police force, and type of road casualties, This corresponds to indirect standardization, not on age and sex as usual but on the characteristics influencing police reporting. Results The national number of injured road casualties, respectively for all severity, and for MAIS3+, are estimated at 285,000 and 24,000 resp. in 2015. The 2015 frequency of sMAIS3+ roadusers consists of 6850 motorized two-wheel users, 6500 car occupants, 3550 cyclists, 3500 pedestrians and 800 others (van, bus, truck users). This confirms the heavy burden suffered by Motorized two-wheel users. Moreover, they only account for 2% of traveled kilometers whereas car occupants account for 70% of traveled kilometers. Also, these results show a different pattern than the number of fatalities, where it is the number of killed car occupants that is the highest. Conclusions The frequency of injured road users, all severities, has been confirmed by other sources, namely: the French national Travel Survey, and by the annual firemen data (they provide first aid on crash scene). Concerning the number of seriously injured road users, the ratio of the number of MAIS3+ casualties divided by the number of fatalities enables country to country comparison

    Chern character, loop spaces and derived algebraic geometry.

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    International audienceIn this note we present a work in progress whose main purpose is to establish a categorified version of sheaf theory. We present a notion of derived categorical sheaves, which is a categorified version of the notion of complexes of sheaves of modules on schemes, as well as its quasi-coherent and perfect versions. We also explain how ideas from derived algebraic geometry and higher category theory can be used in order to construct a Chern character for these categorical sheaves, which is a categorified version of the Chern character for perfect complexes with values in cyclic homology. Our construction uses in an essential way the derived loop space of a scheme X, which is a derived scheme whose theory of functions is closely related to cyclic homology of X. This work can be seen as an attempt to define algebraic analogs of elliptic objects and characteristic classes for them. The present text is an overview of a work in progress and details will appear elsewhere

    The burden of road traffic accidents in a French Departement: the description of the injuries and recent changes

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    International audienceBACKGROUND: A significant reduction in road traffic accidents has been observed since prevention measures were introduced by the French public authorities in 2002. The goals of this study are to describe the burden of road traffic accidents in a French Departement, and to identify changes if any between the periods 1997-2001 and 2002-2006 on the basis of the disability adjusted life years (DALY). METHODS: Years of lost life (YLL) and years lived with disability (YLD) were calculated for two periods using the mortality and incidence data in the Rhone Departement Registry of Road Traffic Accident Casualties. RESULTS: YLD and YLL that are related to road traffic accidents are at their maximum value between 15 and 24 years of age. For men, intracranial fractures and intracranial injuries dominate, and for women it is spinal cord injuries that account for highest rates of YLD. A reduction in the rates of YLL and YLD has been observed for both genders and all age groups between 1997-2001 and 2002-2006. CONCLUSION: The reduction in DALY between the two periods is explained both by the reduction in the number of fatalities and injuries but also by an increase in the age at which they occur

    The injury epidemiology of cyclists based on a road trauma registry

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    <p>Abstract</p> <p>Background</p> <p>Bicycle use has increased in some of France's major cities, mainly as a means of transport. Bicycle crashes need to be studied, preferably by type of cycling. Here we conduct a descriptive analysis.</p> <p>Method</p> <p>A road trauma registry has been in use in France since 1996, in a large county around Lyon (the Rhône, population 1.6 million). It covers outpatients, inpatients and fatalities. All injuries are coded using the Abbreviated Injury Scale (AIS). Proxies were used to identify three types of cycling: learning = children (0-10 years old); sports cycling = teenagers and adults injured outside towns; cycling as means of transport = teenagers and adults injured in towns. The study is based on 13,684 cyclist casualties (1996-2008).</p> <p>Results</p> <p>The percentage of cyclists injured in a collision with a motor vehicle was 8% among children, 17% among teenagers and adults injured outside towns, and 31% among those injured in towns. The percentage of serious casualties (MAIS 3+) was 4.5% among children, 10.9% among adults injured outside towns and 7.2% among those injured in towns. Collisions with motor-vehicles lead to more internal injuries than bicycle-only crashes.</p> <p>Conclusion</p> <p>The description indicates that cyclist type is associated with different crash and injury patterns. In particular, cyclists injured in towns (where cycling is increasing) are generally less severely injured than those injured outside towns for both types of crash (bicycle-only crashes and collisions with a motor vehicle). This is probably due to lower speeds in towns, for both cyclists and motor vehicles.</p

    Six operations and Lefschetz-Verdier formula for Deligne-Mumford stacks

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    Laszlo and Olsson constructed Grothendieck's six operations for constructible complexes on Artin stacks in \'etale cohomology under an assumption of finite cohomological dimension, with base change established on the level of sheaves. In this article we give a more direct construction of the six operations for complexes on Deligne-Mumford stacks without the finiteness assumption and establish base change theorems in derived categories. One key tool in our construction is the theory of gluing finitely many pseudofunctors developed in arXiv:1211.1877. As an application, we prove a Lefschetz-Verdier formula for Deligne-Mumford stacks. We include both torsion and â„“\ell-adic coefficients.Comment: 62 pages. v5, v4: minor improvements; v3: added a Lefschetz-Verdier formula; v2: moved the appendix in v1 to arXiv:1211.187

    Stacky Abelianization of an Algebraic Group

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    Let G be a connected algebraic group and let [G,G] be its commutator subgroup. We prove a conjecture of Drinfeld about the existence of a connected etale group cover H of [G,G], characterized by the following properties: every central extension of G, by a finite etale group scheme, splits over H, and the commutator map of G lifts to H. We prove, moreover, that the quotient stack of G by the natural action of H is the universal Deligne-Mumford Picard stack to which G maps.Comment: 22 Page

    Experience of road and other trauma by the opiate dependent patient: a survey report

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    Background: Trauma plays an important role in the experience of many patients with substance use disorder, but is relatively under-studied particularly in Australia. The present survey examined the lifetime prevalence of various forms of trauma including driving careers in the context of relevant medical conditions. Methods: A survey was undertaken in a family medicine practice with a special interest in addiction medicine in Brisbane, Australia. Results: Of 350 patients surveyed, 220 were substance dependent, and 130 were general medical patients. Addicted patients were younger (mean ± S.D. 33.72 ± 8.14 vs. 44.24 ± 16.91 years, P < 0.0001) and had shorter driving histories (15.96 ± 8.50 vs. 25.54 ± 15.03 years, P < 0.0001). They had less driving related medical problems (vision, spectacle use, diabetes) but more fractures, surgical operations, dental trauma and assaults. Addicted patients also had significantly worse driving histories on most parameters measured including percent with driving suspensions (O.R. = 7.70, C.I. 4.38-13.63), duration of suspensions (1.71 ± 3.60 vs. 0.11 ± 0.31 years, P < 0.0001), number of motor vehicle collisions (2.00 ± 3.30 vs. 1.10 ± 1.32, P = 0.01), numbers of cars repaired (1.73 ± 3.59 vs. 1.08 ± 1.60, P = 0.042), rear end collisions (O.R. = 1.90, CI 1.13-3.25), running away after car crashes (O.R. = 26.37, CI 4.31-1077.48), other people hospitalized (O.R. = 2.00, C.I. 0.93-4.37, P = 0.037) and people killed (17 vs. 0 P = 0.0005). Upon multivariate analysis group membership was shown to be a significant determinant of both cars repaired and cars hit when controlled for length of driving history. Hence use of all types of drugs (O.R. = 10.07, C.I. 8.80-14.72) was more common in addicted patients as were general (O.R. = 3.64, C.I. 2.99-4.80) and road (O.R.= 2.73, C.I. 2.36-3.15) trauma. Conclusion: This study shows that despite shorter driving histories, addicted patients have worse driving careers and general trauma experience than the comparison group which is not explained by associated medical conditions. Trauma is relevant to addiction management at both the patient and policy levels. Substance dependence policies which focus largely on prevention of virus transmission likely have too narrow a public health focus, and tend to engender an unrealistically simplistic and trivialized view of the addiction syndrome. Reduction of drug driving and drug related trauma likely require policies which reduce drug use per se, and are not limited to harm reduction measures alone
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