126 research outputs found

    Non Quadratic Local Risk-Minimization for Hedging Contingent Claims in the Presence of Transaction Costs

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    This paper is devoted to the study of derivative hedging in incomplete markets when frictions are considered. We extend the general local risk minimisation approach introduced in [1] to account for liquidity costs, and derive the corresponding optimal strategies in both the discrete- and continuous-time settings. We examplify our method in the case of stochastic volatility and/or jump-diffusion models.

    Extreme events in optics: Challenges of the MANUREVA project

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    International audienceIn this contribution we describe and discuss a series of challenges and questions relating to understanding extreme wave phenomena in optics. Many aspects of these questions are being studied in the framework of the MANUREVA project: a multidisciplinary consortium aiming to carry out mathematical, numerical and experimental studies in this field. The central motivation of this work is the 2007 results from optical physics [D. Solli et al., Nature 450, 1054 (2007)] that showed how a fibre-optical system can generate large amplitude extreme wave events with similar statistical properties to the infamous hydrodynamic rogue waves on the surface of the ocean. We review our recent work in this area, and discuss how this observation may open the possibility for an optical system to be used to directly study both the dynamics and statistics of extreme-value processes, a potential advance comparable to the introduction of optical systems to study chaos in the 1970s

    Dynamique des solitons de Kuznetsov-Ma observée en optique fibrée non-linéaire

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    International audienceLe soliton de Kuznetzov-Ma est une solution de l'équation de Schrödinger non-linéaire qui a été identifiée dès 1977 mais qui à ce jour n'avait encore jamais été observée expérimentalement. Nous décrivons ici une expérience mettant en évidence la dynamique du soliton KM à travers la propagation non-linéaire de breathers dans une fibre optique

    Peregrine soliton in optical fiber-based systems

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    International audienceWe report the first observation in optics of the Peregrine soliton, a novel class of nonlinear localized structure. Two experimental configurations are explored and the impact of non-ideal initial conditions is discussed

    Characteristics of sound production and associated pharyngeal jaws in the tomtate grunt Haemulon aurolineatum (Cuvier, 1830) in Caribbean reefs

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    International audienceThe ability to produce sounds for acoustic communication is well known in different grunt species (Haemulidae). However, most of the sounds have not been described and the sound-producing mechanism of very few grunt species has been deeply studied. Additional data is needed to search for synapomorphy in the sonic mechanism. This study describes acoustic features and branchial anatomy in Haemulon aurolineatum. Correlations were found between some acoustic features and standard length, showing the largest specimens produced shorter, lower-pitched grunts of higher intensity. Examinations of acoustic features and branchial anatomy show that H. aurolineatum uses the same stridulatory mechanism described previously in H. flavolineatum. The unusual feature of Haemulon species concerns the fourth ceratobranchials. These appear to be part of the lower pharyngeal jaws since they possess firmly attached teeth that face the upper pharyngeal jaws. The stridulation results from the rubbing of both pharyngeal and fourth ceratobranchial teeth. This mechanism is probably common to the 23 Haemulon species, but additional information is needed regarding the mechanism of other Haemulinae species to produce stridulatory sounds. Fourth ceratobranchials could constitute a key element of Haemulinae ability to produce sounds providing an eventual synapomorphic aspect of the mechanism in the family

    Results of successive EORTC-CLG 58 881 and 58 951 trials in paediatric T-cell acute lymphoblastic leukaemia (ALL)

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    Outcomes in childhood T-cell acute lymphoblastic leukaemia (T-ALL) are steadily improving due to intensive therapy. Between 1989 and 2008, 599 children with newly diagnosed T-ALL were enrolled in two successive European Organization for Research and Treatment of Cancer - Children's Leukaemia Group trials (58881 and 58951), both based on the Berlin-Frankfurt-Munster protocol and without cranial irradiation. In the latter trial induction chemotherapy was intensified. The most important randomizations were Medac Escherichia coli asparaginase versus Erwinia asparaginase in trial 58881, and dexamethasone (6 mg/m(2)/day) versus prednisolone (60 mg/m(2)/day) and prolonged versus conventional asparaginase duration in trial 58951. 8-year event-free survival (EFS) increased from 65 center dot 1% to 74 center dot 0% in trial 58951. Improvement was most profound for patients with white blood cell (WBC) counts E. coli asparaginase was associated with longer EFS [hazard ratio (HR) 0 center dot 54, P = 0 center dot 0015] and overall survival (HR 0 center dot 51, P = 0 center dot 0018). Induction therapy with dexamethasone did not improve EFS compared to prednisolone. Remarkably, intensification of central nervous system (CNS)-directed therapy in trial 58951 resulted in fewer bone marrow relapses, while the incidence of CNS relapses remained low. In summary, we showed that adequate asparaginase therapy, intensified induction treatment and intensification of CNS-directed chemotherapy can result in an improvement of outcome in T-ALL patients with good prephase response and initial WBC counts <100 x 10(9)/l, representing approximately 50% of T-ALL patients

    Characteristics and outcomes of neonatal SARS-CoV-2 infection in the UK: a prospective national cohort study using active surveillance.

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    BACKGROUND: Babies differ from older children with regard to their exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, data describing the effect of SARS-CoV-2 in this group are scarce, and guidance is variable. We aimed to describe the incidence, characteristics, transmission, and outcomes of SARS-CoV-2 infection in neonates who received inpatient hospital care in the UK. METHODS: We carried out a prospective UK population-based cohort study of babies with confirmed SARS-CoV-2 infection in the first 28 days of life who received inpatient care between March 1 and April 30, 2020. Infected babies were identified through active national surveillance via the British Paediatric Surveillance Unit, with linkage to national testing, paediatric intensive care audit, and obstetric surveillance data. Outcomes included incidence (per 10 000 livebirths) of confirmed SARS-CoV-2 infection and severe disease, proportions of babies with suspected vertically and nosocomially acquired infection, and clinical outcomes. FINDINGS: We identified 66 babies with confirmed SARS-CoV-2 infection (incidence 5·6 [95% CI 4·3-7·1] per 10 000 livebirths), of whom 28 (42%) had severe neonatal SARS-CoV-2 infection (incidence 2·4 [1·6-3·4] per 10 000 livebirths). 16 (24%) of these babies were born preterm. 36 (55%) babies were from white ethnic groups (SARS-CoV-2 infection incidence 4·6 [3·2-6·4] per 10 000 livebirths), 14 (21%) were from Asian ethnic groups (15·2 [8·3-25·5] per 10 000 livebirths), eight (12%) were from Black ethnic groups (18·0 [7·8-35·5] per 10 000 livebirths), and seven (11%) were from mixed or other ethnic groups (5·6 [2·2-11·5] per 10 000 livebirths). 17 (26%) babies with confirmed infection were born to mothers with known perinatal SARS-CoV-2 infection, two (3%) were considered to have possible vertically acquired infection (SARS-CoV-2-positive sample within 12 h of birth where the mother was also positive). Eight (12%) babies had suspected nosocomially acquired infection. As of July 28, 2020, 58 (88%) babies had been discharged home, seven (11%) were still admitted, and one (2%) had died of a cause unrelated to SARS-CoV-2 infection. INTERPRETATION: Neonatal SARS-CoV-2 infection is uncommon in babies admitted to hospital. Infection with neonatal admission following birth to a mother with perinatal SARS-CoV-2 infection was unlikely, and possible vertical transmission rare, supporting international guidance to avoid separation of mother and baby. The high proportion of babies from Black, Asian, or minority ethnic groups requires investigation. FUNDING: UK National Institute for Health Research Policy Research Programme

    Allogreffe de cellules souches hématopoietiques chez les enfants et les adolescents atteints d'une leucémie myéloïde chronique

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    POITIERS-BU Médecine pharmacie (861942103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
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