Robust calibration of numerical models based on relative regret

Classical methods of parameter estimation usually imply the minimisation of an objective function, that measures the error between some observations and the results obtained by a numerical model. In the presence of random inputs, the objective function becomes a random variable, and notions of robustness have to be introduced. In this paper, we are going to present how to take into account those uncertainties by defining a family of calibration objectives based on the notion of relative-regret with respect to the best attainable performance given the uncertainties and compare it with the minimum in the mean sense, and the minimum of variance

Importance Weighting Approach in Kernel Bayes' Rule

We study a nonparametric approach to Bayesian computation via feature means, where the expectation of prior features is updated to yield expected posterior features, based on regression from kernel or neural net features of the observations. All quantities involved in the Bayesian update are learned from observed data, making the method entirely model-free. The resulting algorithm is a novel instance of a kernel Bayes' rule (KBR). Our approach is based on importance weighting, which results in superior numerical stability to the existing approach to KBR, which requires operator inversion. We show the convergence of the estimator using a novel consistency analysis on the importance weighting estimator in the infinity norm. We evaluate our KBR on challenging synthetic benchmarks, including a filtering problem with a state-space model involving high dimensional image observations. The proposed method yields uniformly better empirical performance than the existing KBR, and competitive performance with other competing methods

Synthesis of 1,5‐Anhydrohexitol Building Blocks for Oligonucleotide Synthesis

This unit describes in detail, the optimized preparations of 1,5‐anhydrohexitol and the 1,5‐anhydrohexitol building blocks for oligonucleotide synthesis (hG, hA, hC, hT).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143593/1/cpnc0109.pd

Maximum Likelihood Learning of Unnormalized Models for Simulation-Based Inference

We introduce two synthetic likelihood methods for Simulation-Based Inference (SBI), to conduct either amortized or targeted inference from experimental observations when a high-fidelity simulator is available. Both methods learn a conditional energy-based model (EBM) of the likelihood using synthetic data generated by the simulator, conditioned on parameters drawn from a proposal distribution. The learned likelihood can then be combined with any prior to obtain a posterior estimate, from which samples can be drawn using MCMC. Our methods uniquely combine a flexible Energy-Based Model and the minimization of a KL loss: this is in contrast to other synthetic likelihood methods, which either rely on normalizing flows, or minimize score-based objectives; choices that come with known pitfalls. We demonstrate the properties of both methods on a range of synthetic datasets, and apply them to a neuroscience model of the pyloric network in the crab, where our method outperforms prior art for a fraction of the simulation budget

Evidential uncertainties on rich labels for active learning

Recent research in active learning, and more precisely in uncertainty sampling, has focused on the decomposition of model uncertainty into reducible and irreducible uncertainties. In this paper, we propose to simplify the computational phase and remove the dependence on observations, but more importantly to take into account the uncertainty already present in the labels, \emph{i.e.} the uncertainty of the oracles. Two strategies are proposed, sampling by Klir uncertainty, which addresses the exploration-exploitation problem, and sampling by evidential epistemic uncertainty, which extends the reducible uncertainty to the evidential framework, both using the theory of belief functions

Analyse des Déterminants de la Résilience aux Changements Climatiques des Cultivateurs du Département de Fresco, Côte d’Ivoire

Climate change is a global challenge facing all of humanity. Farmers, in addition to the many problems they already face, are now facing this new phenomenon. Adaptation currently seems to be one of the best alternatives. The analysis of this adaptation called resilience allows us to know the explanatory factors. In this perspective, the objective of this study is to analyse the climate change resilience of farmers in the Fresco department. Based on Bennett's theory of adaptive dynamics, the working hypothesis is that resilient farmers in Fresco department adopt short cycle crops and combine crops to cope with climate change. Two hundred and sixty (260) respondents, determined by judgment sampling, participated in the study. The investigative tools are documentary research, observation and interview. As for data analysis, the processing method is qualitative and quantitative. In terms of results, it is noted that some crops such as maize, rice, cassava, eggplants, tomatoes, etc., improved by the Centre National de Recherche Agronomique (CNRA) allow farmers in the Fresco area through their short production cycle to not only have access to the local market, but also to maximize their income. In addition, the crop associations currently practiced in this area promote the improvement of productivity through optimal soil use and protection of plantations through extended vegetation cover.Les changements climatiques sont un défi mondial auquel toute l’humanité entière est confrontée. Les cultivateurs, en plus des nombreux problèmes auxquels ils sont déjà confrontés, doivent désormais faire face à ce nouveau phénomène. L'adaptation semble être actuellement l'une des meilleures alternatives. L’analyse de cette adaptation appelée résilience permet d’en connaitre les facteurs explicatifs. C’est dans cette perspective que la présente étude s’inscrit, avec pour objectif d’analyser la résilience aux changements climatiques des cultivateurs dans le département de Fresco. Sur la base de la théorie des dynamiques adaptatives de Bennett, l’hypothèse de travail est que les cultivateurs résilients du département de Fresco adoptent des cultures à cours cycle et associent les cultures pour faire face aux changements climatiques. Deux cents soixante (260) personnes enquêtées, déterminées par échantillonnage de jugement ont participé à l’étude. Les outils d’investigation sont la recherche documentaire, l’observation et l’entretien. Quant à l’analyse des données, le mode de traitement est qualitatif et quantitatif. Au niveau desrésultats, on retient que certaines cultures comme le maïs, le riz, le manioc, les aubergines, la tomate, etc., améliorées par le Centre National de Recherche Agronomique (CNRA) permettent aux cultivateurs dans la zone de Fresco par leur cycle de production court d’avoir non seulement accès au marché local, mais aussi de maximiser leurs revenus. Aussi, les associations culturales actuellement pratiquées dans cette zone favorisent l’amélioration de la productivité grâce à une utilisation optimale du sol et une protection des plantations grâce une couverture végétale prolongée

Real bird dataset with imprecise and uncertain values

The theory of belief functions allows the fusion of imperfect data from different sources. Unfortunately, few real, imprecise and uncertain datasets exist to test approaches using belief functions. We have built real birds datasets thanks to the collection of numerous human contributions that we make available to the scientific community. The interest of our datasets is that they are made of human contributions, thus the information is therefore naturally uncertain and imprecise. These imperfections are given directly by the persons. This article presents the data and their collection through crowdsourcing and how to obtain belief functions from the data

Did glacial advances during the Pleistocene influence differently the demographic histories of benthic and pelagic Antarctic shelf fishes? – Inferences from intraspecific mitochondrial and nuclear DNA sequence diversity

<p>Abstract</p> <p>Background</p> <p>Circum-Antarctic waters harbour a rare example of a marine species flock – the Notothenioid fish, most species of which are restricted to the continental shelf. It remains an open question as to how they survived Pleistocene climatic fluctuations characterised by repeated advances of continental glaciers as far as the shelf break that probably resulted in a loss of habitat for benthic organisms. Pelagic ecosystems, on the other hand, might have flourished during glacial maxima due to the northward expansion of Antarctic polar waters. In order to better understand the role of ecological traits in Quaternary climatic fluctuations, we performed demographic analyses of populations of four fish species from the tribe Trematominae, including both fully benthic and pelagic species using the mitochondrial cytochrome b gene and an intron from the nuclear S7 gene.</p> <p>Results</p> <p>Nuclear and cytoplasmic markers showed differences in the rate and time of population expansions as well as the likely population structure. Neutrality tests suggest that such discordance comes from different coalescence dynamics of each marker, rather than from selective pressure. Demographic analyses based on intraspecific DNA diversity suggest a recent population expansion in both benthic species, dated by the cyt b locus to the last glacial cycle, whereas the population structure of pelagic feeders either did not deviate from a constant-size model or indicated that the onset of the major population expansion of these species by far predated those of the benthic species. Similar patterns were apparent even when comparing previously published data on other Southern Ocean organisms, but we observed considerable heterogeneity within both groups with regard to the onset of major demographic events and rates.</p> <p>Conclusion</p> <p>Our data suggest benthic and pelagic species reacted differently to the Pleistocene ice-sheet expansions that probably significantly reduced the suitable habitat for benthic species. However, the asynchronous timing of major demographic events observed in different species within both "ecological guilds", imply that the species examined here may have different population and evolutionary histories, and that more species should be analysed in order to more precisely assess the role of life history in the response of organisms to climatic changes.</p