1,184 research outputs found

    Khinchin's theorem in Teichmüller dynamics

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    This thesis is concerned with two themes which are strictly linked with each other, and therefore will be developed in parallel. The first one is dynamics in Teichmueller space. The Teichmueller space of a (topological, closed and orientable) surface S is defined as the set of the complex structures one can endow S with, up to isotopies. Such a space can be given a structure of geodesic metric space. The description of this structure requires the notion of flat structures on the underlying surface, i.e. flat Riemannian metrics with conical singularities, such that a foliation in straight lines in each direction is defined. The space of all flat structures is a sort of tangent bundle to the Teichmueller space, and the geodesic flow, knows as Teichmueller flow, has a simple description in these terms. It becomes interesting from a dynamical viewpoint when projected onto the moduli space, namely the set of the complex structures up to diffeomorphisms. Invariant subspaces under the flow are called strata; we are concerned in particular with dynamics in the strata made up by translation structures, a subspecies of the flat structures. The second theme treated in this work are interval exchange maps (i.e.m.s)i.e. injective maps of an interval which are locally a translation except at finitely many singularities. They are completely determined by providing some combinatorial data as well as the length data of the sub-intervals. If one considers an adequate leftmost portion of the considered interval, the first return map of the i.e.m. on this portion is a new i.e.m.. This yields a dynamics on the parameter space for i.e.m.s, called Rauzy dynamics. The themes above are linked on two levels. First of all, if one fixes a translation surface, the first return map induced by the flow in vertical direction on a horizontal segment is an i.e.m.; and a `generic' i.e.m. can always be obtained this way. But a link at a higher level is possible, too: the Teichmueller flow admits a transverse section such that the return map can be interpreted as Rauzy dynamics. Chapter 0 of the thesis is an introduction: it includes the preliminary material from the theory of dynamical systems which will be used in this work, as well as a description of the simplest case of the theory, represented by flat tori and rotations of the circumference. In Chapter 1 Teichmueller dynamics is formally, but rapidly, introduced; whereas Chapter 2 is concerned with the formalism related to interval exchange maps and Rauzy dynamics. Moreover, it is explained how it is possible to switch from this setting to the one of translation structures, and conversely. The first half of Chapter 3 treats, still in an extremely concise manner, classical questions related to the themes above. In particular it deals with ergodicity of i.e.m.s and of the Teichmueller and Rauzy dynamics and briefly introduces the Kontsevich-Zorich cocycle. The chapter ends with a technical discussion needed for the results tackled in the following chapters: its protagonists will be the reduced triples for an i.e.m. T, namely triples (b,a;n) where b is a singular point for T1T^{-1}, a is a singular point for T, and n is a positive integer, such that no singularities for T1,...,TnT^{-1},...,T^-n appears between Tn(b)T^n(b) and a. Chapter 4 thus deals with a first generalisation of a theorem of A.Ya. Khinchin, found by Luca Marchese (2010). The Khinchin theorem in its classical formulation states a condition for a Diophantine inequality to have finitely, or infinitely many, solutions. Its generalisation to i.e.m.s states: Let f(n) be a positive, decreasing sequence. We are concerned with the quantity of solutions (b,a;n) to the condition Tn(a)b<f(n)|T^n(a)-b|<f(n) for a fixed i.e.m. T, where b is a singular point of T1T^-1, and a is a singular point for T. If the sequence f(n) has a finite sum, then solutions are finitely many for almost any T; if nf(n) is still a decreasing sequence, with infinite sum, then solutions are infinitely many for almost any T. This result will be partially proved. It is interesting not only as a property of singularities of an i.e.m., but also because it yields a weaker version of a theorem of Jon Chaika, which states a similar property for generic points. Chapter 5 is again about translation surfaces. The theorem above is restated as a property of lengths of connections, namely segments connecting two singular points on a translation surface. Hence it is possible to gain another result of Chaika, which gives a property of 'strong recurrence' of foliations. And, eventually, this restatement of the generalised Khinchin theorem yields a logarithm law for the Teichmueller flow: Let X be a translation surface, and let Sys(X) be the minimum length of a connection of X. Denote gtg^t the Teichmueller flow. Then, for almost any X, it holds that lim sup[log(Sys(gt(X))]/(logt)=1/2\limsup [-\log (Sys(g^t(X))]/(\log t)=1/2

    Vida y milagros de la bienaventurada santa Catherina de Sena

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    Sign.: A6, B-Q8Autor tomado de h. IXMarca tip. en el v. de la última h.ColofónPort. grab. xil. y a dos tintasGrab. xil., a toda plana, y a dos tintas en A6 v.Errores de fol. Delante de la primera h. numerada (la IX) solo hay seis h.Texto a dos col.Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

    Modelo higro-termo-mecánico para estructuras de hormigón armado expuestas al fuego

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    Cuando una estructura de hormigón armado queda expuesta a la acción del fuego se roducen, tanto en el hormigón como en el acer. un conjunto de fenómenos físico-químicos que pueden comprometer la estabilidad de la misma. Entre los procesos más importantes destaca el de la eclosión (spalling). Se considera que las posibles causas del spalling pueden ser un elevado crecimiento de la presión en los poros (spalling hidraúlico) o un exagerado aumento de las tensiones de compresión debidas a la dilatación térmica restringida. Para poder tener en cuenta en el análisis el spalling hidraúlico es necesario considerar un modelo que tenga en cuenta la componente hídrica del hormigón. En esta monografía se presenta un modelo higro-termo-mecánico que permite representar el comportamiento general del hormigón armado expuesto a elevadas temperaturas y en particular simular el fenómeno de spalling.Postprint (published version

    Single center experience with laparoscopic adrenalectomy on a large clinical series

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    BACKGROUND: Laparoscopic adrenalectomy is considered the gold standard technique for the treatment of benign small and medium size adrenal masses (<6 cm), due to low morbidity rate, short hospitalization and patient rapid recovery. The aim of our study is to analyse the feasibility and efficiency of this surgical approach in a broad spectrum of adrenal gland pathologies. METHODS: Pre-operative, intra-operative and post-operative data from 126 patients undergone laparoscopic adrenalectomy between January 2003 and December 2015 were retrospectively collected and reviewed. Diagnosis was obtained on the basis of clinical examination, laboratory values and imaging techniques. Doxazosin was preoperatively administered in case of pheochromocytoma while spironolactone and potassium were employed to treat Conn's disease. Laparoscopic adrenalectomies were all performed by the same surgeon (CG). First 30 procedures were considered as learning curve adrenalectomies. RESULTS: One hundred twenty-six patients were included in the study. Functioning tumors were diagnosed in 84 patients, 27 patients were affected by pheochromocytomas, 29 by Conn's disease, 28 by Cushing disease. Surgery mean operative time was 137.33 min (range 100-180) during the learning curve adrenalectomies and 96.5 min (range 75-110) in subsequent procedures. Mean blood loss was respectively 160.2 ml (range 60-280) and 90.5 ml (range 50-200) in the first 30 procedures and the subsequent ones. Only one conversion to open surgery occurred. No post-operative major complications were observed, while minor complications occurred in 8 patients (0,79%). In 83 out of 84 functioning neoplasms, laparoscopic adrenalectomy was effective in normalization of endocrine profile. CONCLUSIONS: Laparoscopic adrenalectomy is a safe and feasible procedure, even for functioning masses and pheochromocytomas. A multidisciplinary team including endocrinologists, endocrine surgeons and anaesthesiologists, is recommended in the management of adrenal pathology, and adrenal surgery should be performed in referral high volume centers. A thirty-procedures learning curve is recommended to improve surgical outcomes

    Treatment of de novo femoro-popliteal lesions with a new Drug Coated Balloon: early experience of a single Center in the first 50 patients

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    Angioplasty with drug-coated balloon (DCB) is an emerging and reliable method for the treatment of femoro-popliteal lesions. We report our experience with the Stellarex™ DCB in the first 50 patients. Methods - From July 2015 to November 2017, 50 patients (41 M, 9F), medium age (64 ± 7.4 year) were subject to 33 angioplasties (PTAs) for femoro-popliteal lesions with a paclitaxel-coated balloon (Stellarex™). Based upon clinical data sixteen patients had severe claudication (56% - Rutherford class 3); ten patients suffered from ischemic rest pain (34% - Rutherford class 4); and five presented minor tissue loss (10% - Rutherford class 5). 42% of patients showed femoro-popliteal lesion TASC-II B, and 58% presented lesions pertaining to TASC-II C. Results - Immediate technical success was 100% without perioperative complications. Primary patency rate was 94% at twelve months. In three cases restenosis (6%) was detected within a year from procedure, and a further PTA DCB was performed with primary assisted patency rates of 100% at twelve months. Two patients underwent major lower limb amputation. Three patients died during follow-up and one patient was lost at follow-up. Conclusion - DCB angioplasty with Stellarex™ is a viable alternative to traditional endovascular procedures proving satisfactory primary patency rates at twelve months. Based on our experience, treatment with DCB is a first choice technique for non-complex de novo lesions of the femoro – popliteal tract

    Can Preening Contribute to Influenza A Virus Infection in Wild Waterbirds?

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    Wild aquatic birds in the Orders Anseriformes and Charadriiformes are the main reservoir hosts perpetuating the genetic pool of all influenza A viruses, including pandemic viruses. High viral loads in feces of infected birds permit a fecal-oral route of transmission. Numerous studies have reported the isolation of avian influenza viruses (AIVs) from surface water at aquatic bird habitats. These isolations indicate aquatic environments have an important role in the transmission of AIV among wild aquatic birds. However, the progressive dilution of infectious feces in water could decrease the likelihood of virus/host interactions. To evaluate whether alternate mechanisms facilitate AIV transmission in aquatic bird populations, we investigated whether the preen oil gland secretions by which all aquatic birds make their feathers waterproof could support a natural mechanism that concentrates AIVs from water onto birds' bodies, thus, representing a possible source of infection by preening activity. We consistently detected both viral RNA and infectious AIVs on swabs of preened feathers of 345 wild mallards by using reverse transcription–polymerase chain reaction (RT-PCR) and virus-isolation (VI) assays. Additionally, in two laboratory experiments using a quantitative real-time (qR) RT-PCR assay, we demonstrated that feather samples (n = 5) and cotton swabs (n = 24) experimentally impregnated with preen oil, when soaked in AIV-contaminated waters, attracted and concentrated AIVs on their surfaces. The data presented herein provide information that expands our understanding of AIV ecology in the wild bird reservoir system

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

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    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon μ\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, μμ\mu\mu or eμe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

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    A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction
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