Dynamics of meromorphic maps with small topological degree I: from cohomology to currents

We consider the dynamics of a meromorphic map on a compact kahler surface whose topological degree is smaller than its first dynamical degree. The latter quantity is the exponential rate at which its iterates expand the cohomology class of a kahler form. Our goal in this article and its sequels is to carry out a conjectural program for constructing and analyzing a natural measure of maximal entropy for each such map. Here we take the first step, converting information about the linear action of the map on cohomology to invariant currents with special geometric structure. We also give some examples and identify some additional properties of maps on irrational surfaces and of maps whose invariant cohomology classes have vanishing self-intersection.Comment: Final version, to appear in Indiana University Mathematics Journal. Among other changes, discussion of polynomial maps is improve

Dynamics of meromorphic maps with small topological degree III: geometric currents and ergodic theory

We continue our study of the dynamics of mappings with small topological degree on (projective) complex surfaces. Previously, under mild hypotheses, we have constructed an ergodic ``equilibrium'' measure for each such mapping. Here we study the dynamical properties of this measure in detail: we give optimal bounds for its Lyapunov exponents, prove that it has maximal entropy, and show that it has product structure in the natural extension. Under a natural further assumption, we show that saddle points are equidistributed towards this measure. This generalize results that were known in the invertible case and is, to our knowledge, one among not very many instances in which a natural invariant measure for a non-invertible dynamical system is well-understood.Comment: v3. Exposition improved. Final version, to appear in Ann. Scient. de l'EN

Presentations of children to emergency departments across Europe and the COVID-19 pandemic: A multinational observational study

During the initial phase of the Coronavirus Disease 2019 (COVID-19) pandemic, reduced numbers of acutely ill or injured children presented to emergency departments (EDs). Concerns were raised about the potential for delayed and more severe presentations and an increase in diagnoses such as diabetic ketoacidosis and mental health issues. This multinational observational study aimed to study the number of children presenting to EDs across Europe during the early COVID-19 pandemic and factors influencing this and to investigate changes in severity of illness and diagnoses. Routine health data were extracted retrospectively from electronic patient records of children aged 18 years and under, presenting to 38 EDs in 16 European countries for the period January 2018 to May 2020, using predefined and standardized data domains. Observed and predicted numbers of ED attendances were calculated for the period February 2020 to May 2020. Poisson models and incidence rate ratios (IRRs), using predicted counts for each site as offset to adjust for case-mix differences, were used to compare age groups, diagnoses, and outcomes. Reductions in pediatric ED attendances, hospital admissions, and high triage urgencies were seen in all participating sites. ED attendances were relatively higher in countries with lower SARS-CoV-2 prevalence (IRR 2·26, 95% CI 1·90 to 2·70, p < 0.001) and in children aged <12 months (12 to <24 months IRR 0·86, 95% CI 0·84 to 0·89; 2 to <5 years IRR 0·80, 95% CI 0·78 to 0·82; 5 to <12 years IRR 0·68, 95% CI 0·67 to 0·70; 12 to 18 years IRR 0·72, 95% CI 0·70 to 0·74; versus age <12 months as reference group, p < 0.001). The lowering of pediatric intensive care admissions was not as great as that of general admissions (IRR 1·30, 95% CI 1·16 to 1·45, p < 0.001). Lower triage urgencies were reduced more than higher triage urgencies (urgent triage IRR 1·10, 95% CI 1·08 to 1·12; emergent and very urgent triage IRR 1·53, 95% CI 1·49 to 1·57; versus nonurgent triage category, p < 0.001). Reductions were highest and sustained throughout the study period for children with communicable infectious diseases. The main limitation was the retrospective nature of the study, using routine clinical data from a wide range of European hospitals and health systems. Reductions in ED attendances were seen across Europe during the first COVID-19 lockdown period. More severely ill children continued to attend hospital more frequently compared to those with minor injuries and illnesses, although absolute numbers fell. ISRCTN91495258 https://www.isrctn.com/ISRCTN91495258

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P &lt; 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Risk of serious treatable neurological emergencies in children with febrile seizure : an example of use of electronical medical records in the purpose of clinical research

Entre 2 et 5% des enfants de 6 mois à 5 ans présentent au moins un épisode de Crise d’Épilepsie en contexte Fébrile (CEF). Bien que généralement bénignes, ces crises sont associées à un risque d’urgences neurologiques graves et curables dont l’élimination requiert la réalisation d’examens complémentaires douloureux et/ou irradiants. Actuellement, ce risque est évalué en fonction de trois facteurs : l’âge de l’enfant, le caractère simple ou complexe de la crise, et l’examen clinique.Cette thèse avait pour objectif de tester l’hypothèse que parmi les enfants consultant pour une CEF, seuls ceux avec un examen clinique anormal présentent un risque d’urgence neurologique grave et urgent. Pour ce faire, nous avons créé un outil informatique permettant une recherche exhaustive de cas parmi un million de dossiers médicaux informatisés dans sept services d’urgences pédiatriques entre 2007 et 2011. Nous avons alors identifié : les visites d’enfants présentant une CEF. Nous avons ensuite évalué le risque d’urgence neurologique grave et curable associé à ces visites, notamment lorsque l’examen clinique au décours était normal. Nous n’avons retrouvé aucune urgence neurologique grave et curable parmi les enfants consultant pour une CEF avec un examen clinique normal au décours, quels que soient l’âge et les caractéristiques de la crise. Ce travail de thèse associé aux données de la littérature confirme notre hypothèse et souligne la nécessité de recommandations quant à la prise en charge de ces enfants. Enfin, cette thèse constitue l’occasion de mener une réflexion méthodologique quant à l’utilisation de dossiers médicaux informatisés pour la recherche clinique.Febrile seizures (FS) affect 2% to 5% of children aged 6 months to 5 years of age. Although FS are usually benign, they are associated with serious treatable neurological emergencies. Nowadays, three factors are used to evaluate this risk: the age of the child, whether the FS is simple or complex and the features of the clinical exam. The performance of a lumbar puncture and an emergent neuroimaging are required in order to rule out these emergencies. However, a lumbar puncture is painful and neuroimaging is irradiant. The objective of this thesis was to investigate the hypothesis that among children experiencing a FS, only those with an abnormal clinical exam are at risk of serious, treatable neurological emergencies. We first created an informatics tool in order to exhaustively search for cases among more than one million electronic medical records from seven pediatric emergency departments (PED) between 2007 and 2011. Then, we identified visits of children with a FS. Finally, we evaluated the proportion of serious, treatable neurological emergencies associated with these visits, and more specifically with visits of children with a normal clinical exam.We found no serious treatable neurological emergencies among children visiting the ED for a FS with a normal clinical exam, whatever the age and the features of the seizure were. The studies described in this thesis associated with the available data in the literature support our hypothesis and highlight the need of guidelines regarding the management of these children. Finally, this thesis gives us the opportunity to discuss some considerations on the use of electronic medical records for clinical research

Risque d'urgence neurologique grave et curable parmi les enfants présentant une crise d'épilepsie en contexte fébrile : un exemple d'utilisation des dossiers médicaux informatisés des urgences pour la recherche clinique

Febrile seizures (FS) affect 2% to 5% of children aged 6 months to 5 years of age. Although FS are usually benign, they are associated with serious treatable neurological emergencies. Nowadays, three factors are used to evaluate this risk: the age of the child, whether the FS is simple or complex and the features of the clinical exam. The performance of a lumbar puncture and an emergent neuroimaging are required in order to rule out these emergencies. However, a lumbar puncture is painful and neuroimaging is irradiant. The objective of this thesis was to investigate the hypothesis that among children experiencing a FS, only those with an abnormal clinical exam are at risk of serious, treatable neurological emergencies. We first created an informatics tool in order to exhaustively search for cases among more than one million electronic medical records from seven pediatric emergency departments (PED) between 2007 and 2011. Then, we identified visits of children with a FS. Finally, we evaluated the proportion of serious, treatable neurological emergencies associated with these visits, and more specifically with visits of children with a normal clinical exam.We found no serious treatable neurological emergencies among children visiting the ED for a FS with a normal clinical exam, whatever the age and the features of the seizure were. The studies described in this thesis associated with the available data in the literature support our hypothesis and highlight the need of guidelines regarding the management of these children. Finally, this thesis gives us the opportunity to discuss some considerations on the use of electronic medical records for clinical research.Entre 2 et 5% des enfants de 6 mois à 5 ans présentent au moins un épisode de Crise d’Épilepsie en contexte Fébrile (CEF). Bien que généralement bénignes, ces crises sont associées à un risque d’urgences neurologiques graves et curables dont l’élimination requiert la réalisation d’examens complémentaires douloureux et/ou irradiants. Actuellement, ce risque est évalué en fonction de trois facteurs : l’âge de l’enfant, le caractère simple ou complexe de la crise, et l’examen clinique.Cette thèse avait pour objectif de tester l’hypothèse que parmi les enfants consultant pour une CEF, seuls ceux avec un examen clinique anormal présentent un risque d’urgence neurologique grave et urgent. Pour ce faire, nous avons créé un outil informatique permettant une recherche exhaustive de cas parmi un million de dossiers médicaux informatisés dans sept services d’urgences pédiatriques entre 2007 et 2011. Nous avons alors identifié : les visites d’enfants présentant une CEF. Nous avons ensuite évalué le risque d’urgence neurologique grave et curable associé à ces visites, notamment lorsque l’examen clinique au décours était normal. Nous n’avons retrouvé aucune urgence neurologique grave et curable parmi les enfants consultant pour une CEF avec un examen clinique normal au décours, quels que soient l’âge et les caractéristiques de la crise. Ce travail de thèse associé aux données de la littérature confirme notre hypothèse et souligne la nécessité de recommandations quant à la prise en charge de ces enfants. Enfin, cette thèse constitue l’occasion de mener une réflexion méthodologique quant à l’utilisation de dossiers médicaux informatisés pour la recherche clinique

Geometric properties of maximal psh functions

International audienc

Visite de non contre-indication à la pratique de la course à pied (pratique médicale et avis des coureurs enquête réalisée au départ du marathon de Lyon 2005)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF