Critically Examining the Claimed Value of Convolutions over User-Item Embedding Maps for Recommender Systems

In recent years, algorithm research in the area of recommender systems has shifted from matrix factorization techniques and their latent factor models to neural approaches. However, given the proven power of latent factor models, some newer neural approaches incorporate them within more complex network architectures. One specific idea, recently put forward by several researchers, is to consider potential correlations between the latent factors, i.e., embeddings, by applying convolutions over the user-item interaction map. However, contrary to what is claimed in these articles, such interaction maps do not share the properties of images where Convolutional Neural Networks (CNNs) are particularly useful. In this work, we show through analytical considerations and empirical evaluations that the claimed gains reported in the literature cannot be attributed to the ability of CNNs to model embedding correlations, as argued in the original papers. Moreover, additional performance evaluations show that all of the examined recent CNN-based models are outperformed by existing non-neural machine learning techniques or traditional nearest-neighbor approaches. On a more general level, our work points to major methodological issues in recommender systems research.Comment: Source code available here: https://github.com/MaurizioFD/RecSys2019_DeepLearning_Evaluatio

Viscoelastometric Testing to Assess Hemostasis of COVID-19: A Systematic Review

Infection by SARS-CoV-2 is associated with a high risk of thrombosis. The laboratory documentation of hypercoagulability and impaired fibrinolysis remains a challenge. Our aim was to assess the potential usefulness of viscoelastometric testing (VET) to predict thrombotic events in COVID-19 patients according to the literature. We also (i) analyzed the impact of anticoagulation and the methods used to neutralize heparin, (ii) analyzed whether maximal clot mechanical strength brings more information than Clauss fibrinogen, and (iii) critically scrutinized the diagnosis of hypofibrinolysis. We performed a systematic search in PubMed and Scopus databases until 31st December 2020. VET methods and parameters, and patients' features and outcomes were extracted. VET was performed for 1063 patients (893 intensive care unit (ICU) and 170 non-ICU, 44 studies). There was extensive heterogeneity concerning study design, VET device used (ROTEM, TEG, Quantra and ClotPro) and reagents (with non-systematic use of heparin neutralization), timing of assay, and definition of hypercoagulable state. Notably, only 4 out of 25 studies using ROTEM reported data with heparinase (HEPTEM). The common findings were increased clot mechanical strength mainly due to excessive fibrinogen component and impaired to absent fibrinolysis, more conspicuous in the presence of an added plasminogen activator. Only 4 studies out of the 16 that addressed the point found an association of VETs with thrombotic events. So-called functional fibrinogen assessed by VETs showed a variable correlation with Clauss fibrinogen. Abnormal VET pattern, often evidenced despite standard prophylactic anticoagulation, tended to normalize after increased dosing. VET studies reported heterogeneity, and small sample sizes do not support an association between the poorly defined prothrombotic phenotype of COVID-19 and thrombotic events

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Serotonin Reduction in Post-acute Sequelae of Viral Infection

Post-acute sequelae of COVID-19 (PASC, Long COVID ) pose a significant global health challenge. The pathophysiology is unknown, and no effective treatments have been found to date. Several hypotheses have been formulated to explain the etiology of PASC, including viral persistence, chronic inflammation, hypercoagulability, and autonomic dysfunction. Here, we propose a mechanism that links all four hypotheses in a single pathway and provides actionable insights for therapeutic interventions. We find that PASC are associated with serotonin reduction. Viral infection and type I interferon-driven inflammation reduce serotonin through three mechanisms: diminished intestinal absorption of the serotonin precursor tryptophan; platelet hyperactivation and thrombocytopenia, which impacts serotonin storage; and enhanced MAO-mediated serotonin turnover. Peripheral serotonin reduction, in turn, impedes the activity of the vagus nerve and thereby impairs hippocampal responses and memory. These findings provide a possible explanation for neurocognitive symptoms associated with viral persistence in Long COVID, which may extend to other post-viral syndromes

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

Violence rurale, réforme agraire et politique en République d'Haïti (chroniques de la plaine de l'Artibonite)

La thèse analyse le rapport entre formes de structuration du pouvoir politique et formes légitimes de tenure foncière en Haïti, dans la plaine de l'Aribonite. Celle-ci a connu de violents conflits terriens suite à des travaux d'irrigation qui ont valorisé les terres rizicoles et entraîné une concentration foncière. La reconstitution des conflits montre la coïncidence entre des pics de violence et des évènements politiques majeurs. Les récits de conflits mêlent histoires familiales, intrigues politiques, clivages idéologiques, juges vénaux et répression armée. À la chute de la dictature duvaliériste en 1986, une génération militante paysanne née au contact du christianisme de libération se bat pour le droit à la terre, la défense des droits humains et contre l'impunité. La réforme agraire bute sur la pression démographique, l'enchevêtrement des formes de tenure et des traditions politiques antidémocratiques. La faillite du processus de transition démocratique conduit à l'échec de la réforme.The thesis analyzes the relationship between forms of the political power and legitimate forms of land tenure in Haiti, in the plain of Artibonite. This district has witnessed violent land conflicts since irrigation works have been carried out, in the fifties, giving greater value to these rice-growing lands and involving a land concentration. The constitution of the conflicts mix family and political intrigues, ideological cleavages, venal judges and armed repression. With the fall of the duvalierist dictatorship in 1986, a new generation of peasant activists born in contact with Theology of Liberation fights for access to land, for human rights and against impunity. The land reform confronts an enormous demographic pressure, the entanglement of land tenure systems and the antidemocratic political traditions. The bankruptcy of the democratic transition led to the failure of the land reform.PARIS3-BU (751052102) / SudocSudocFranceF

Implants mandibulaires (une nécessité actuelle dans la thérapeutique de l'édentement total mandibulaire)

NICE-Antenne de St Jean d'Angely (060882105) / SudocNICE-BU Médecine Odontologie (060882102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Intérêt du score de probabilité clinique de Genève pour limiter le risque de démarche inappropriée (étude rétrospective d'une cohorte de patients admis dans un service d'urgence pour suspicion d'embolie pulmonaire)

INTRODUCTION : La maladie veineuse thrombo-embolique reste une des premières causes de mortalité. L angio-scanner thoracique est l examen diagnostique de référence de l embolie pulmonaire (EP). La prévalence de l EP parmi les patients ayant bénéficié d un angio-scanner thoracique est modeste dans les études de registres, d environ 10 %. L objectif primaire était de comparer la performance diagnostique du score de Genève avec la suspicion clinique de l urgentiste. METHODES : Cette étude de cohorte unicentrique, rétrospective a inclus les patients suspects d EP, admis aux urgences de la clinique mutualiste de Grenoble, du 1er août 2011 au 1er août 2012. L'indication de l angio-scanner thoracique a été réévaluée en réalisant a posteriori, un score de Genève modifié. RESULTATS : L analyse a porté sur 1874 patients. L étude a confirmé la performance évaluée par l aire sous la courbe ROC du score de Genève modifié significativement supérieure à celle de l intuition clinique seule. La prévalence de l EP parmi les angio-scanners thoraciques réalisées était de 13,2% dans notre cohorte en comparaison avec une prévalence de 23 à 26% retrouvée dans la littérature lorsque le score de Genève est utilisé. L'utilisation d'une stratégie diagnostique fondée sur des scores de probabilité clinique aurait probablement permis d'éviter 93 angioscanners inutiles sur les 789 réalisés. DISCUSSION : L utilisation d outils d aide à la stratégie diagnostique par des guides écrits ou en format numérique incluant un score pourrait augmenter la performance des médecins face à une suspicion d EP.INTRODUCTION: Venous thromboembolic disease remains a leading cause of mortality. Chest CT scan is the diagnostic gold standard of pulmonary embolism (PE) . The prevalence of PE among patients who underwent chest CT scan is modest in previous studies, about 10%. The primary objective was to compare the diagnostic performance of the Geneva score with the subjective clinical suspicion in the emergency room . METHODS: This retrospective single-center cohort study, included patients with suspected PE, admitted to the clinique mutualiste s emergency, Grenoble, France, 1 August 2011 to 1 August 2012. The indication of the chest CT scan was reassessed by conducting a score of Geneva modified, a posteriori. RESULTS: The analysis included 1874 patients. The study confirmed the assessed of the modified Geneva score by the area under the ROC curve, significantly higher than subjective clinical intuition performance. The prevalence of PE among chest CT scan made was 13.2 % in our cohort compared with a prevalence of 23-26 % found in the literature when the Geneva s score is used. The use of a diagnostic strategy based on clinical probability scores would probably have avoided the unnecessary 93 of 789 chest CT scan done. DISCUSSION: The use of diagnostic written or digital strategy s guides including a score could increase the performance with suspected PE patients.GRENOBLE1-BU Médecine pharm. (385162101) / SudocSudocFranceF