92 research outputs found
Primal-dual formulation of the Dynamic Optimal Transport using Helmholtz-Hodge decomposition
This work deals with the resolution of the dynamic optimal transport (OT) problem between 1D or 2D images in the fluid mechanics framework of Benamou-Brenier [6]. The numerical resolution of this dynamic formulation of OT, despite the successful application of proximal methods [36] is still computationally demanding. This is partly due to a space-time Laplace operator to be solved at each iteration, to project back to a divergence free space. In this paper, we develop a method using the Helmholtz-Hodge decomposition [23] in order to enforce the divergence-free constraint throughout the iterations. We prove that the functional we consider has better convexity properties on the set of constraints. In particular we explain that in 1D+time, this formulation is equivalent to the resolution of a minimal surface equation. We then adapt the first order primal-dual algorithm for convex problems of Chambolle and Pock [12] to solve this new problem, leading to an algorithm easy to implement. Besides, numerical experiments demonstrate that this algorithm is faster than state of the art methods for dynamic optimal transport [36] and efficient with real-sized images
Semaine d'Etude MathĂ©matiques et Entreprises 6 : Analyse statistique des deÌfauts en eÌlectronique analogique
Nous nous inteÌressons aÌ des donneÌes issues de mesures de tensions sur des circuits eÌlectroniques analogiques. Plus preÌciseÌment, il s'agit de proposer une analyse de courbes repreÌsentant l'eÌvolution en fonction du temps des tensions en diffeÌrents nĆuds d'un circuit eÌlectronique. Notre objectif est de proposer une analyse automatiseÌe de la qualiteÌ des courbes. Plus preÌciseÌment, nous proposons ici des meÌthodes statistiques d'analyse de donneÌes capable de : -- Identifier d'eÌventuels patterns dans les courbes (classification), -- Isoler les courbes preÌsentant des "anomalies" (deÌtection de courbes suspectes)
Primal-dual formulation of the Dynamic Optimal Transport using Helmholtz-Hodge decomposition
This work deals with the resolution of the dynamic optimal transport (OT) problem between 1D or 2D images in the fluid mechanics framework of Benamou-Brenier [6]. The numerical resolution of this dynamic formulation of OT, despite the successful application of proximal methods [36] is still computationally demanding. This is partly due to a space-time Laplace operator to be solved at each iteration, to project back to a divergence free space. In this paper, we develop a method using the Helmholtz-Hodge decomposition [23] in order to enforce the divergence-free constraint throughout the iterations. We prove that the functional we consider has better convexity properties on the set of constraints. In particular we explain that in 1D+time, this formulation is equivalent to the resolution of a minimal surface equation. We then adapt the first order primal-dual algorithm for convex problems of Chambolle and Pock [12] to solve this new problem, leading to an algorithm easy to implement. Besides, numerical experiments demonstrate that this algorithm is faster than state of the art methods for dynamic optimal transport [36] and efficient with real-sized images
Investigation of MALDI-TOF Mass Spectrometry for Assessing the Molecular Diversity of Campylobacter jejuni and Comparison with MLST and cgMLST: A Luxembourg One-Health Study
There is a need for active molecular surveillance of human and veterinary Campylobacter
infections. However, sequencing of all isolates is associated with high costs and a considerable
workload. Thus, there is a need for a straightforward complementary tool to prioritize isolates to
sequence. In this study, we proposed to investigate the ability of MALDI-TOF MS to pre-screen C.
jejuni genetic diversity in comparison to MLST and cgMLST. A panel of 126 isolates, with 10 clonal
complexes (CC), 21 sequence types (ST) and 42 different complex types (CT) determined by the
SeqSphere+ cgMLST, were analysed by a MALDI Biotyper, resulting into one average spectra per
isolate. Concordance and discriminating ability were evaluated based on protein profiles and different
cut-offs. A random forest algorithm was trained to predict STs. With a 94% similarity cut-off, an
AWC of 1.000, 0.933 and 0.851 was obtained for MLSTCC, MLSTST and cgMLST profile, respectively.
The random forest classifier showed a sensitivity and specificity up to 97.5% to predict four different
STs. Protein profiles allowed to predict C. jejuni CCs, STs and CTs at 100%, 93% and 85%, respectively.
Machine learning and MALDI-TOF MS could be a fast and inexpensive complementary tool to give
an early signal of recurrent C. jejuni on a routine basis
Combination of MALDI-TOF Mass Spectrometry and Machine Learning for Rapid Antimicrobial Resistance Screening: The Case of Campylobacter spp.
While MALDI-TOF mass spectrometry (MS) is widely considered as the reference
method for the rapid and inexpensive identification of microorganisms in routine
laboratories, less attention has been addressed to its ability for detection of antimicrobial
resistance (AMR). Recently, some studies assessed its potential application together
with machine learning for the detection of AMR in clinical pathogens. The scope of
this study was to investigate MALDI-TOF MS protein mass spectra combined with
a prediction approach as an AMR screening tool for relevant foodborne pathogens,
such as Campylobacter coli and Campylobacter jejuni. A One-Health panel of 224
C. jejuni and 116 C. coli strains was phenotypically tested for seven antimicrobial
resistances, i.e., ciprofloxacin, erythromycin, tetracycline, gentamycin, kanamycin,
streptomycin, and ampicillin, independently, and were submitted, after an on- and
off-plate protein extraction, to MALDI Biotyper analysis, which yielded one average
spectra per isolate and type of extraction. Overall, high performance was observed
for classifiers detecting susceptible as well as ciprofloxacin- and tetracycline-resistant
isolates. A maximum sensitivity and a precision of 92.3 and 81.2%, respectively, were
reached. No significant prediction performance differences were observed between on and off-plate types of protein extractions. Finally, three putative AMR biomarkers for
fluoroquinolones, tetracyclines, and aminoglycosides were identified during the current
study. Combination of MALDI-TOF MS and machine learning could be an efficient and
inexpensive tool to swiftly screen certain AMR in foodborne pathogens, which may
enable a rapid initiation of a precise, targeted antibiotic treatment
Global assessment of marine plastic exposure risk for oceanic birds
Plastic pollution is distributed patchily around the worldâs oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species
Global assessment of marine plastic exposure risk for oceanic birds
Plastic pollution is distributed patchily around the world's oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.B.L.C., C.H., and A.M. were funded by the Cambridge Conservation Initiativeâs Collaborative Fund sponsored by the Prince Albert II of Monaco Foundation. E.J.P. was supported by the Natural Environment Research Council C-CLEAR doctoral training programme (Grant no. NE/S007164/1). We are grateful to all those who assisted with the collection and curation of tracking data. Further details are provided in the Supplementary Acknowledgements. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Peer reviewe
Global assessment of marine plastic exposure risk for oceanic birds
Plastic pollution is distributed patchily around the worldâs oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species
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 60â109 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:
âTypicalâ 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 (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). 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
IntroducciĂł al turisme sostenible mitjançant un projecte interdisciplinar en el cicle formatiu de grau superior dâagĂšncies de viatge
[cat] Estem vivint una situaciĂł dâemergĂšncia planetĂ ria marcada per greus
problemes estretament relacionats: degradaciĂł i contaminaciĂł dels
ecosistemes, de les culturals locals, esgotament de recursos, desequilibris
insostenibles, conflictes, pĂšrdua de la diversitat biolĂČgica i cultural... Per tant, Ă©s
per aixĂČ que cal assumir un compromĂs perquĂš lâeducaciĂł en general doni
molta importĂ ncia al que estĂ passat en el mĂłn, amb la finalitat de proporcionar
als alumnes de lâĂ mbit del turisme una visiĂł global dels problemes i fomentar
actituds i comportaments favorables per a lâassoliment dâun desenvolupament
sostenible .
El present treball pretĂ©n aportar propostes perquĂš lâeducaciĂł, i en el nostre cas
el cicle formatiu de grau superior dâagĂšncies de viatge, ajudi a formar futurs
professionals del sector turĂstic conscients dels problemes del sector i informats
sobre la importĂ ncia del desenvolupament sostenible del turisme i, per tant,
donar pas a professionals capacitats per millorar aquesta situaciĂł actual.
Pensem que la millor forma dâensenyar als nostre alumnes a entendre i valorar
un tema tan complex com és el turisme sostenible és mitjançant un projecte
didĂ ctic interdisciplinari, on gairebĂ© tots els mĂČduls es vegin involucrats i
tothom treballi de forma col·laborativa i transversal.
Per tant, el que pretenem amb aquest treball Ă©s explicar com desenvoluparĂem
un projecte interdisciplinari amb tema eix El turisme sostenible i que tindria com
a principal objectiu formar futurs professional compromesos amb el turisme
sostenible i els problemes del sector
- âŠ