La Recherche Research Articles

De l’affaire Dreyfus à l’affaire Albertine. Sociopoétique du complot dans À la recherche du temps perdu

French Belle Époque is characterized by a spy mania. During this time, fights against traitors are multiplying. In this article, we would like to show how this social discourse gets into Proust’s novel À la recherche du temps perdu and fuels at the same time an imagination and a poetics of the conspiracy. First, this imagination belongs to armchair conspiracists. Between Dreyfus affair and Eulenburg affair they have indeed a lot to do. This imagination belongs then to the narrator, who is convinced that he is at the heart of a conspiracy, which turns the novel into a paranoid detective story. But he is perhaps the victim of a trick played on him by his imagination. Affected in turn by suspicion, the reader must also become a detective, in search of the traces that form the frame of the conspiracy narrative. More generally, the analysis of the Proustian imagination of conspiracy brings to light a number of interactions concerning a society that also seems to have entered the age of suspicion, fragmented into “little clans” that operate on the model of secret societies.

The impact of Charcot-Leyden Crystal protein on mesothelioma chemotherapy: targeting eosinophils for enhanced chemosensitivity

In mesothelioma (MPM), clinical evidence indicates that the absolute eosinophil count negatively correlates with overall survival and response to standard chemotherapy. Since eosinophils poorly infiltrate MPM tumours, we hypothesised that endocrine rather than paracrine pathways mediate the therapeutic response. We thus studied the effect of eosinophil-associated factors on response to chemotherapy in mesothelioma. The culture supernatant conditioned by primary human eosinophils was added to mesothelioma cells in presence of the standard chemotherapeutic regimen. The effectiveness of an anti-eosinophil treatment was evaluated in a preclinical model of C57BL/6 mice transplanted with mesothelioma tumour cells. Supernatant of eosinophils differentiated from EOL1 cells or directly isolated from peripheral blood inhibited apoptosis induced by cisplatin and pemetrexed in 2D cultures and in spheroids. Transcriptomic analysis indicated that the anti-apoptotic effect mediated by eosinophils involved molecular interactions with the Charcot-Leyden Crystal protein or Galectin-10 (CLC-P/Gal10). The functional relevance of CLC-P/Gal10 was demonstrated by antibody-mediated depletion. Recombinant human CLC-P/Gal10 mimicked the anti-apoptotic activity of eosinophil-derived supernatants. In the mouse model, eosinophilia did not significantly affect tumour growth but altered the response to chemotherapy. Finally, pretreatment of eosinophilia with the anti-Siglec-F antibody before chemotherapy restored the effectiveness of the treatment. This study provides a mechanistic rationale to clinical evidence correlating the poor outcome of patients with mesothelioma and with eosinophil-derived CLC-P/Gal10, opening new prospects for intervention in this fatal solid tumour. Belgian Foundation against Cancer, Fonds National de la Recherche Scientifique (FNRS), Télévie, Foundation Léon Fredericq, ULiège.

Science Mapping of Open-Access Articles on Data Visualisation: A Scopus-based Analysis

The prime objective of the present study is to analyze the impact of open-access publishing on research publications in data visualization journal research papers using scientometric indicators and science mapping techniques. A total of 9,018 publication records were extracted from the Scopus database for five years, from 2018 to 2022. The parameters used for the present study are open-access publication trends and their impact on the number of publications and citations, most prolific authors, organizations, countries, journals, etc. The study results indicate that 60.55% of articles on data visualization were published as open access, and the trend of open-access publication has grown exponentially. The study further found that open-access articles have a better academic impact than overall articles published. Huamin Qu of Hong Kong University of Science and Technology has contributed the highest number (22) of open-access articles on data visualization; the authors affiliated with the Centre National de la Recherche Scientifique (CNRS), Paris, have contributed the highest (116) OA articles; and the United States was the topmost productive country with the highest (1,809) OA articles. IEEE Transactions on Visualization and Computer Graphics was the most preferred journal among researchers on data visualization to publish their research as open-access articles.

Back to the future - 20 years of progress and developments in photonic microscopy and biological imaging.

In 2023, the ImaBio consortium (imabio-cnrs.fr), an interdisciplinary life microscopy research group at the Centre National de la Recherche Scientifique, celebrated its 20th anniversary. ImaBio contributes to the biological imaging community through organization of MiFoBio conferences, which are interdisciplinary conferences featuring lectures and hands-on workshops that attract specialists from around the world. MiFoBio conferences provide the community with an opportunity to reflect on the evolution of the field, and the 2023 event offered retrospective talks discussing the past 20 years of topics in microscopy, including imaging of multicellular assemblies, image analysis, quantification of molecular motions and interactions within cells, advancements in fluorescent labels, and laser technology for multiphoton and label-free imaging of thick biological samples. In this Perspective, we compile summaries of these presentations overviewing 20 years of advancements in a specific area of microscopy, each of which concludes with a brief look towards the future. The full presentations are available on the ImaBio YouTube channel (youtube.com/@gdrimabio5724).

Intra-operative imaging solutions for surgeons

Intra-operative imaging solutions for surgeons Birgitta Dresp from the Centre National de la Recherche Scientifique (CNRS) discusses the challenges associated with intra-operative imaging technology and the quest for gold standards of surgical skill. In minimally invasive interventional procedures such as laparoscopic surgery, surgeons do not have a direct view of the organ or tissue they are interacting with but are constrained to navigate the surgical instruments on the basis of image views provided by dedicated camera systems. Image-guided interventions have been on the rise in recent years as they are less invasive than traditional methods and are believed to enable more accurate surgical gestures. Yet, the surgeon’s brain needs to re-interpret the visual information available in the image given. This has to be achieved swiftly and reliably for controlling the instruments with the greatest ease and accuracy, yielding the most precise surgical gestures in the shortest time possible. How can we assess critical parameters of surgical skill and its evolution with time and training under different conditions imposed by different technological solutions?

Humoral signatures of Caspr2-antibody spectrum disorder track with clinical phenotypes and outcomes.

Immunoglobulin (Ig) G4 auto-antibodies (Abs) against contactin-associated protein-like 2 (Caspr2), a transmembrane cell adhesion protein expressed in the central and peripheral nervous system, are found in patients with a broad spectrum of neurological symptoms. While the adoptive transfer of Caspr2-specific IgG induces brain pathology in susceptible rodents, the mechanisms by which Caspr2-Abs mediate neuronal dysfunction and translate into clinical syndromes are incompletely understood. We use a systems-level approach combined with high-dimensional characterization of Ab-associated immune features to deeply profile humoral biosignatures in patients with Caspr2-Ab-associated neurological syndromes. We identify two signatures strongly associated with two major clinical phenotypes, limbic encephalitis (LE) and predominant peripheral nerve hyperexcitability without LE (non-LE). Caspr2-IgG Fc-driven pro-inflammatory features, characterized by increased binding affinities for activating Fcγ receptors (FcγRs) and C1q, along with a higher prevalence of IgG1-class Abs, in addition to IgG4, are strongly associated with LE. Both the occurrence of Caspr2-specific IgG1 and higher serum levels of interleukin (IL)-6 and IL-15, along with increased concentrations of biomarkers reflecting neuronal damage and glial cell activation, are associated with poorer clinical outcomes at 1-year follow-up. The presence of IgG1 isotypes and Fc-mediated effector functions control the pathogenicity of Caspr2-specific Abs to induce LE. Biologics targeting FcR function might potentially restrain Caspr2-Ab-induced pathology and improve clinical outcomes. This study was funded by a German-French joint research program supported by the German Research Foundation (DFG) and the Agence Nationale de la Recherche (ANR) and by the Interdisciplinary Centre for Clinical Research (IZKF) Münster.

Value-Positivity for Matrix Games

Matrix games are the most basic model in game theory, and yet robustness with respect to small perturbations of the matrix entries is not fully understood. In this paper, we introduce value positivity and uniform value positivity, two properties that refine the notion of optimality in the context of polynomially perturbed matrix games. The first concept captures how the value depends on the perturbation parameter, and the second consists of the existence of a fixed strategy that guarantees the value of the unperturbed matrix game for every sufficiently small positive parameter. We provide polynomial-time algorithms to check whether a polynomially perturbed matrix game satisfies these properties. We further provide the functional form for a parameterized optimal strategy and the value function. Finally, we translate our results to linear programming and stochastic games, where value positivity is related to the existence of robust solutions. Funding: This research was supported by Fondation CFM pour la Recherche, the H2020 European Research Council [Grant ERC-CoG-863818 (ForM-SMArt)], the Austrian Science Fund [Grant 10.55776/COE12], ANID Chile [Grant ACT210005], and Agence Nationale de la Recherche [Grant ANR-21-CE40-0020].

Deep learning based x-ray spectrometer for high repetition rate characterization of betatron radiation

Betatron radiation produced from a laser-wakefield accelerator is a broadband, hard x-ray (>1 keV) source that has been used in a variety of applications in medicine, engineering, and fundamental science. Further development and optimization of stable, high repetition rate (HRR) (>1 Hz) betatron sources will provide a means to extend their application base to include single-shot dynamical measurements of ultrafast processes or dense materials. Recent advances in laser technology used in such experiments have enabled increases in shot-rate and system stability, providing improved statistical analysis and detailed parameter scans. However, unique challenges exist at high repetition rate, where data throughput and source optimization are now limited by diagnostic acquisition rates and analysis. Here, we present the development of a machine-learning algorithm for the real-time analysis of betatron radiation. We report on the fielding of this deep learning algorithm for online source characterization at the Institut National de la Recherche Scientifique's Advanced Laser Light Source. By fine-tuning an algorithm originally trained on a fully synthetic dataset using a subset of experimental data, the algorithm can predict the betatron critical energy with a percent error of 7.2 % with a reconstruction time of 1.5 ms, providing a valuable tool for real-time, multi-objective optimization at HRR.

Impact of financial incentives introduced during the COVID-19 pandemic on nursing staff: a mixed-method protocol

IntroductionThe COVID-19 pandemic has had a major impact on nursing staff, resulting in alarming turnover rates. As part of the Quebec (Canada) government’s response to the pandemic, nurses have been...

Effect of Fertilization on the Severity of Attack by the Defoliator Caterpillar (Noorda blitealis Walker, 1859) and on the Yield of Moringa (Moringa oleifera Lam, Lam. moringa (Moringa oleifera Lam, 1785)

Purpose: Moringa, which is increasingly grown pure in semi-intensive and intensive systems, requires adequate fertilization to produce well. In some cases, this operation can inhibit the development of its bioaggressors. The aim of this study was to determine the effect of different types of fertilization on the defoliator caterpillar (Noorda blitealis) and moringa production. Methodology: The trial was conducted on the Kalapaté experimental station belonging to the Institut ational de la recherche agronomique du Niger over two seasons. The experimental design was a split-plot with 4 replications in which the main plots were represented by fertilizer types (NPK, cattle, poultry and compost). The elementary plots were made up of fertilizer doses (0, 0, 5, 1 and 1.5 kg/ha for organic fertilizers, and 0, 3, 6 and 9 g/package for NPK). The severity of the caterpillar attack and moringa yield were recorded. Findings: The results showed that NPK acted faster than other fertilizers in reducing the severity of attack by N. blitealis. The reduction rate was 28.40% in the first season compared with cattle manure, which is the most attacked. In the second season, compost had a similar effect to NPK. Both reduced this parameter by over 45% each compare to cattle and poultry manure. Their action consequently increased moringa yield compared with cattle manure and poultry droppings. Also, a negative linear relationship was noted between manure dose and severity of attack, while the dose-yield relationship was of the second-degree polynomial type. Unique Contribution to Theory, Practice and Policy: Compost can therefore be used to minimize attacks by Noorda blitealis and can enable sustainable production without any risk of toxicity from synthetic pesticides. In view of these results, moringa growers must compost cattle and poultry manure, and all other organic sources of fertilization, before any application.

Genetic Diversity of Red Onion Using Microsatellite (SSRs) Markers

Onion is one of the most widely grown vegetable crops, but also one of the least genetically characterized. It is diploid (2n=16) and allogamous, which makes its selection program a little more demanding. Molecular markers make selection easier. The variability of individual phenotypes is a peculiarity of the living world. Some of these variations are expressed at the phenotypic level (morphology, physiology, behavior, etc.), while others are hidden, and their detection requires the use of adapted techniques (variability of proteins or DNA sequences). For this purpose, 23 onion varieties collected by INRAN (Institut National de la Recherche Agronomique) from Niger and the three onion powder mixes received from R&D Nestlé Abidjan. The genetic analysis was performed using molecular markers (SSRs). The results demonstrated a large inter variability in the onion varieties obtained from INRAN collection. An equivalent source of genetic diversity is also observed inside the main number of these varieties expertized.

From Folklore to Proust: A Quest across Symbolic Universes

This study explores the intersection of folklore and literature, specifically examining how a methodology developed for interpreting wondertales can be applied to a complex literary corpus, such as Marcel Proust’s À la recherche du temps perdu (In Search of Lost Time). The discussion proposes a case study for the use of allomotifs, or interchangeable motifs, to understand symbolic patterns in Proust’s literary work. The paper lays bare a widespread metaphorical field in wondertales, then follows its complications in the Proustian corpus. It suggests that Proust’s œuvre, much like folklore, operates within a symbolic universe where binary oppositions, such as good and evil or male and female, are fluid and dynamic. The discussion shows that Proust’s literary imagination aligns surprisingly well with the workings of folklore. This hybrid space of the imagination challenges conventional distinctions between folklore and literature, and brings to mind Lévi-Strauss’ erstwhile ruminations on the pensée sauvage.

Islet-after-kidney transplantation versus kidney alone in kidney transplant recipients with type 1 diabetes (KAIAK): a population-based target trial emulation in France

Islet transplantation has been associated with better metabolic control and quality of life than insulin treatment alone, but direct evidence of its effect on hard clinical endpoints is scarce. We aimed to assess the effect of islet transplantation on patient-graft survival in kidney transplant recipients with type 1 diabetes. In this retrospective cohort study, we enrolled all patients with type 1 diabetes who received a kidney graft in France during the study period, identified from the CRISTAL nationwide registry. Non-inclusion criteria included recipients from transplant centres that never proposed islet transplantation during the study period, recipients with a functional pancreas throughout the follow-up duration, recipients with more than two kidney transplants, HLA-sensitised recipients, recipients with less than 1 year of follow-up after kidney transplantation, misclassified recipients with type 2 diabetes, recipients aged over 65 years, recipients of kidney grafts from Donation after Circulatory Death donors, recipient with HIV or hepatitis, recipients with cancer, and recipients of combined liver-kidney transplants. Patients who also received islet-after-kidney (IAK) transplantation were compared with controls who received kidney transplantation alone according to a 1:2 matching method based on time-dependent propensity scores, ensuring patients comparability at the time of islet transplantation. The primary outcome was patient-graft survival, a composite outcome defined by death, re-transplantation, or return to dialysis. Between Jan 1, 2000, and Dec 31, 2017, 2391 patients with type 1 diabetes were identified as having received a kidney transplant, 47 patients of whom also received an islet transplantation. 2002 patients were not eligible for islet transplantation and 62 were excluded due to missing data. 327 eligible recipients from 15 centres were included in the study dataset for the target trial emulation. 40 patients who received IAK transplantation were successfully matched to 80 patients who received kidney transplantation alone. 13 (33%) of 40 patients in the IAK transplantation group returned to dialysis or died, compared with 36 (45%) of 80 patients in the kidney transplantation alone group. We found a significant benefit of islet transplantation compared with kidney transplantation alone on patient-graft survival, with a hazard ratio (HR) of 0·44 (95% CI 0·23-0·88; p=0·022), mainly explained by a protective effect on the risk of death (HR 0·41, 0·13-0·91; p=0·042). There was no meaningful association between IAK and death-censored graft survival (0·73, 0·30-1·89; p=0·36). In kidney transplant recipients with type 1 diabetes, IAK transplantation was associated with a significantly better patient-graft survival compared with kidney transplantation alone, mainly due to a protective effect on the risk of death. These results potentially serve as compelling grounds for advocating wider access to islet transplantation in patients with type 1 diabetes undergoing kidney transplant, as reimbursement of islet transplantation is provided in few countries worldwide. Programme Hospitalier de la Recherche Clinique, Fondation pour la Recherche Medicale, and Fonds de Dotation Line Renaud-Loulou Gasté.

Correlated Equilibria in Large Anonymous Bayesian Games

We consider multipopulation Bayesian games with a large number of players. Each player aims at minimizing a cost function that depends on this player’s own action, the distribution of players’ actions in all populations, and an unknown state parameter. We study the nonatomic limit versions of these games and introduce the concept of Bayes correlated Wardrop equilibrium, which extends the concept of Bayes correlated equilibrium to nonatomic games. We prove that Bayes correlated Wardrop equilibria are limits of action flows induced by Bayes correlated equilibria of the game with a large finite set of small players. For nonatomic games with complete information admitting a convex potential, we prove that the set of correlated and of coarse correlated Wardrop equilibria coincide with the set of probability distributions over Wardrop equilibria and that all equilibrium outcomes have the same costs. We get the following consequences. First, all flow distributions of (coarse) correlated equilibria in convex potential games with finitely many players converge to mixtures of Wardrop equilibria when the weight of each player tends to zero. Second, for any sequence of flows satisfying a no-regret property, its empirical distribution converges to the set of distributions over Wardrop equilibria, and the average cost converges to the unique Wardrop cost. Funding: This work was partially supported by European Cooperation in Science and Technology Action 16228 GAMENET. F. Koessler acknowledges the support of the Agence Nationale de la Recherche [Grant StratCom ANR-19-CE26-0010-01]. M. Scarsini acknowledges the support of the Gruppo Nazionale per l’Analisi Matematica, la Probabilità e le loro Applicazioni project [Grant CUP_E53C22001930001], the Ministero dell’Università e della Ricerca Progetti di Rilevante Interesse Nazionale [Grant 2022EKNE5K], and the European Union-Next Generation EU, component M4C2, investment 1.1 (Ministero dell’Università e della Ricerca Progetti di Rilevante Interesse Nazionale Piano Nazionale di Ripresa e Resilienza) [Grant P2022XT8C8]. T. Tomala gratefully acknowledges the support of the HEC foundation and Agence Nationale de la Recherche/Investissements d’Avenir [Grant ANR-11-IDEX-0003/Labex Ecodec/ANR-11-LABX-0047].

Bibliometric Analysis of a Comprehensive of Culture and Symbol in Character Animation during (2004–2024)

The analysis of academic research on animated characters in the animation industry effectively summarises the current state of scholarly research on animated characters through a variety of software tools such as CiteSpace, VOS viewer, HistCite, and Bibliometrix analysis, and visually charts and formulates this data. Through study and research, it that the United States is (278) the most prolific country, and the United States has the highest intermediary centrality, as well as the most Centre National de la Recherche Scientifique (CNRS) and PEOPLES R CHINA are the most cited organizations and Countries/Regions with the highest intermediary centrality and Countries/Regions with the highest citation explosiveness, respectively. This study also suggests possible challenges and future directions in character design for animated characters.

Diagnostic and prognostic biomarkers in immune checkpoint inhibitor-related encephalitis: a retrospective cohort study

Immune checkpoint inhibitor-related encephalitis (ICI-encephalitis) is not well characterised and diagnostic and prognostic biomarkers are lacking. We aimed to comprehensively characterise ICI-encephalitis and identify diagnostic biomarkers and outcome predictors. This retrospective observational study included all patients with ICI-encephalitis studied in the French Reference Centre on Paraneoplastic Neurological Syndromes (PNS) and Autoimmune Encephalitis (2015-2023). ICI encephalitis was considered definite in case of inflammatory findings at paraclinical tests and/or well-characterised neural antibodies. Predictors of immune-related adverse event (irAE) treatment response, defined as a Common Terminology Criteria for Adverse Events v5.0 grade<3at any time after therapeutic intervention, were assessed by logistic regression analysis, and predictors of mortality by Cox regression analysis. Neurofilament light chain (NfL) was measured by enzyme-linked immunosorbent assay. Sixty-seven patients with definite encephalitis were identified (median age, 69 years; 66% male). A focal syndrome was observed in 43/67 patients (64%; limbic encephalitis, cerebellar ataxia, and/or brainstem encephalitis), while 24/67 (36%) had meningoencephalitis, a non-focal syndrome with altered mental status (22/24 patients, 92%) and pleocytosis (24/24 patients, 100%). Patients with focal encephalitis more frequently had abnormal brain MRI (26/42, 62% versus 8/24, 33%, p=0.025), PNS-related antibodies (36/43, 84% versus 1/24, 4%, p<0.001), and neuroendocrine cancers (22/43, 51% versus 1/24, 4%; p<0.001) than patients with meningoencephalitis. Focal encephalitis patients had a lower rate of irAE treatment response (7/39, 18%) and higher mortality (27/43, 63%) compared to meningoencephalitis patients (12/22, 77% and 5/24, 21%, respectively, p<0.001 each). PNS-related antibodies were associated with less irAE treatment response, independently of age, sex, and baseline severity (adjusted OR 0.05; 95%CI [0.01; 0.19]; p<0.001) as well as higher mortality, independently of age and cancer type (adjusted HR 5.07; 95% CI [2.12; 12.12]; p<0.001). Serum NfL discriminated patients with definite ICI-encephalitis (n=27) from cancer-matched controls (n=16; optimal cut-off >273.5pg/mL, sensitivity 81%, specificity 88%, AUC 0.87, 95% CI [0.76; 0.98]) and irAE treatment responders (n=10) from non-responders (n=17, optimal cut-off >645pg/mL, sensitivity 90%, specificity 65%; AUC 0.75, 95% CI [0.55; 0.94]). ICI-encephalitis corresponds to a set of clinically-recognisable syndromes. Patients with focal encephalitis, PNS-related antibodies, and/or higher serum NfL have low irAE treatment response rates. Research is needed on the underlying immunopathogenesis to foster therapeutic innovations. Agence Nationale de la Recherche.

Son et lumière in Proust

ABSTRACT Marcel Proust’s À la recherche du temps perdu is underpinned by an enduring tension between sight and the other senses. Conventional scholarship on Proust claims that the visual pole of this tension is linked to the intellect, as opposed to the association of the remaining senses with intuition and the unfathomable. This reading, however, presents an oversimplification of the complex economy of the senses explored by Proust insofar as it falls prey to visualism, a theoretical predisposition characterised by a double reduction of the perceptual experience. Challenging this tendency, this article draws on sensorial cross-modality and multisensory processes in order to interrogate the connection between sunlight and song in Proust’s novel. In particular, we focus on the ‘little barometer man’ at the start of La Prisonnière, whom the narrator anticipates singing on his death bed ‘if there is a blink of sun’. We also consider this Proustian connection between song and sunlight in light of a longer tradition, including St Francis of Assisi’s ‘Canticle of Brother Sun’ and the statue of Memnon’s dawn song. Proust’s consequent demythologising of light and his materialist approach to song support an attempt to consider light shorn of its usual metaphorical connotations.

Ex vivo susceptibility to antimalarial drugs and polymorphisms in drug resistance genes of African Plasmodium falciparum, 2016-2023: a genotype-phenotype association study.

Given the altered responses to both artemisinins and lumefantrine in Eastern Africa, monitoring antimalarial drug resistance in all African countries is paramount. We measured the susceptibility to six antimalarials using ex vivo growth inhibition assays (IC50) for a total of 805 Plasmodium falciparum isolates obtained from travelers returning to France (2016-2023), mainly from West and Central Africa. Isolates were sequenced using molecular inversion probes (MIPs) targeting fourteen drug resistance genes across the parasite genome. Ex vivo susceptibility to several drugs has significantly decreased in 2019-2023 versus 2016-2018 parasite samples: lumefantrine (median IC50: 23·0 nM [IQR: 14·4-35·1] in 2019-2023 versus 13·9 nM [8·42-21·7] in 2016-2018, p<0·0001), monodesethylamodiaquine (35·4 [21·2-51·1] versus 20·3 nM [15·4-33·1], p<0·0001), and marginally piperaquine (20·5 [16·5-26·2] versus 18.0 [14·2-22·4] nM, p<0·0001). Only four isolates carried a validated pfkelch13 mutation. Multiple mutations in pfcrt and one in pfmdr1 (N86Y) were significantly associated with altered susceptibility to multiple drugs. The susceptibility to lumefantrine was altered by pfcrt and pfmdr1 mutations in an additive manner, with the wild-type haplotype (pfcrt K76-pfmdr1 N86) exhibiting the least susceptibility. Our study on P. falciparum isolates from West and Central Africa indicates a low prevalence of molecular markers of artemisinin resistance but a significant decrease in susceptibility to the partner drugs that have been the most widely used since a decade -lumefantrine and amodiaquine. These phenotypic changes likely mark parasite adaptation to sustained drug pressure and call for intensifying the monitoring of antimalarial drug resistance in Africa. This work was supported by the French Ministry of Health (grant to the French National Malaria Reference Center) and by the Agence Nationale de la Recherche (ANR-17-CE15-0013-03 to JC). JAB was supported by NIH R01AI139520. JR postdoctoral fellowship was funded by Institut de Recherche pour le Développement.

Improving supercooled liquid water representation in the microphysical scheme ICE3

AbstractMost numerical weather prediction (NWP) models have a significant bias in predicting supercooled liquid water (SLW). For this reason, icing risk diagnostic tools do not use supercooled liquid water forecast by the models as an input parameter, but rather temperature and humidity, which are forecast better than SLW. The main objective of this study is to improve the SLW representation in the microphysical scheme ICE3 (Three Ice categories) used in the operational Applications de la Recherche à l'Opérationnel à Méso‐Echelle (AROME) model. For this purpose, several parametrizations of the microphysical processes were evaluated to find a better representation of SLW in the Mesoscale Non‐Hydrostatic model (MESO‐NH), which also uses ICE3. Elements of the microphysical scheme of the HARMONIE‐AROME model and work carried out by the Centre National de Recherches Météorologiques (CNRM) have been tested and compared with the current scheme. After a preliminary study, three parametrizations of the microphysical scheme were selected, in which the processes of ice initiation, snow and graupel collection of cloud droplets, condensation, Bergeron–Findeisen, and saturation adjustment were modified. Then, MESO‐NH simulations were performed and compared with observations from the In‐Cloud ICing and Large‐drop Experiment (ICICLE) airborne campaign. Three case studies were used with different icing weather conditions such as freezing rain, freezing drizzle, lake effect, etc. The results show a better representation of SLW with a greater presence of cloud droplets for colder temperatures up to 30 C. However, the liquid water content remains underestimated and the ice mass is overestimated. The ice initiation and cloud droplet collection by snow and graupel play a major role in the SLW representation. Parametrizations with restrictive ice initiation criteria reduce cloud droplet consumption and provide better agreement with observations. The results are promising and need to be investigated further with more cases and in the operational model AROME.

On the Convex Formulations of Robust Markov Decision Processes

Robust Markov decision processes (MDPs) are used for applications of dynamic optimization in uncertain environments and have been studied extensively. Many of the main properties and algorithms of MDPs, such as value iteration and policy iteration, extend directly to RMDPs. Surprisingly, there is no known analog of the MDP convex optimization formulation for solving RMDPs. This work describes the first convex optimization formulation of RMDPs under the classical sa-rectangularity and s-rectangularity assumptions. By using entropic regularization and exponential change of variables, we derive a convex formulation with a number of variables and constraints polynomial in the number of states and actions, but with large coefficients in the constraints. We further simplify the formulation for RMDPs with polyhedral, ellipsoidal, or entropy-based uncertainty sets, showing that, in these cases, RMDPs can be reformulated as conic programs based on exponential cones, quadratic cones, and nonnegative orthants. Our work opens a new research direction for RMDPs and can serve as a first step toward obtaining a tractable convex formulation of RMDPs. Funding: The work in the paper was supported, in part, by NSF [Grants 2144601 and 1815275]; and Agence Nationale de la Recherche [Grant 11-LABX-0047].