Ensuring access to high-quality resources reduces the impacts of heat stress on bees

Pollinators are experiencing declines globally, negatively affecting the reproduction of wild plants and crop production. Well-known drivers of these declines include climatic and nutritional stresses, such as a change of dietary resources due to the degradation of habitat quality. Understanding potential synergies between these two important drivers is needed to improve predictive models of the future effects of climate change on pollinator declines. Here, bumblebee colony bioassays were used to evaluate the interactive effects of heat stress, a reduction of dietary resource quality, and colony size. Using a total of 117 colonies, we applied a fully crossed experiment to test the effect of three dietary quality levels under three levels of heat stress with two colony sizes. Both nutritional and heat stress reduced colony development resulting in a lower investment in offspring production. Small colonies were much more sensitive to heat and nutritional stresses than large ones, possibly because a higher percentage of workers helps maintain social homeostasis. Strikingly, the effects of heat stress were far less pronounced for small colonies fed with suitable diets. Overall, our study suggests that landscape management actions that ensure access to high-quality resources could reduce the impacts of heat stress on bee decline.info:eu-repo/semantics/publishedVersio

WorldSense: A Synthetic Benchmark for Grounded Reasoning in Large Language Models

We propose WorldSense, a benchmark designed to assess the extent to which LLMs are consistently able to sustain tacit world models, by testing how they draw simple inferences from descriptions of simple arrangements of entities. Worldsense is a synthetic benchmark with three problem types, each with their own trivial control, which explicitly avoids bias by decorrelating the abstract structure of problems from the vocabulary and expressions, and by decorrelating all problem subparts with the correct response. We run our benchmark on three state-of-the-art chat-LLMs (GPT3.5, GPT4 and Llama2-chat) and show that these models make errors even with as few as three objects. Furthermore, they have quite heavy response biases, preferring certain responses irrespective of the question. Errors persist even with chain-of-thought prompting and in-context learning. Lastly, we show that while finetuning on similar problems does result in substantial improvements -- within- and out-of-distribution -- the finetuned models do not generalise beyond a constraint problem space

Contribution of Cerebellar Sensorimotor Adaptation to Hippocampal Spatial Memory

Complementing its primary role in motor control, cerebellar learning has also a bottom-up influence on cognitive functions, where high-level representations build up from elementary sensorimotor memories. In this paper we examine the cerebellar contribution to both procedural and declarative components of spatial cognition. To do so, we model a functional interplay between the cerebellum and the hippocampal formation during goal-oriented navigation. We reinterpret and complete existing genetic behavioural observations by means of quantitative accounts that cross-link synaptic plasticity mechanisms, single cell and population coding properties, and behavioural responses. In contrast to earlier hypotheses positing only a purely procedural impact of cerebellar adaptation deficits, our results suggest a cerebellar involvement in high-level aspects of behaviour. In particular, we propose that cerebellar learning mechanisms may influence hippocampal place fields, by contributing to the path integration process. Our simulations predict differences in place-cell discharge properties between normal mice and L7-PKCI mutant mice lacking long-term depression at cerebellar parallel fibre-Purkinje cell synapses. On the behavioural level, these results suggest that, by influencing the accuracy of hippocampal spatial codes, cerebellar deficits may impact the exploration-exploitation balance during spatial navigation

Monitoring bee health in European agroecosystems using wing morphology and fat bodies

Current global change substantially threatens pollinators, which directly impacts the pollination services underpinning the stability, structure and functioning of ecosystems. Amongst these threats, many synergistic drivers, such as habitat destruction and fragmentation, increasing use of agrochemicals, decreasing resource diversity, as well as climate change, are known to affect wild and managed bees. Therefore, reliable indicators for pollinator sensitivity to such threats are needed. Biological traits, such as phenotype (e.g. shape, size and asymmetry) and storage reserves (e.g. fat body size), are important pollinator traits linked to reproductive success, immunity, resilience and foraging efficiency and, therefore, could serve as valuable markers of bee health and pollination service potential. This data paper contains an extensive dataset of wing morphology and fat body content for the European honeybee (Apis mellifera) and the buff-tailed bumblebee (Bombus terrestris) sampled at 128 sites across eight European countries in landscape gradients dominated by two major bee-pollinated crops (apple and oilseed rape), before and after focal crop bloom and potential pesticide exposure. The dataset also includes environmental metrics of each sampling site, namely landscape structure and pesticide use. The data offer the opportunity to test whether variation in the phenotype and fat bodies of bees is structured by environmental factors and drivers of global change. Overall, the dataset provides valuable information to identify which environmental threats predominantly contribute to the modification of these traits

Thermomechanical characterization and wear mechanisms identifica- tion of a low-pressure and high-pressure abradable coating under extreme

La réduction des jeux fonctionnels aubes/carter permet d’augmenter le rendement global d’un turboréacteur en limitant les fuites inter-étages. Cependant, les vibrations inhérentes au système ou l’ingestion de corps étrangers tend à produire des interactions aube/carter initiées en bout d’aube qui peuvent mener à la ruine du turboréacteur. L’utilisation de revêtements dits « abradables » permet de limiter la conséquence de ces interactions. En cas de contact avec les parties tournantes, le matériau abradable va « s’abrader » de façon préférentielle par rapport au bout d’aube en limitant les énergies d’interaction. Ces matériaux sont étudiés depuis de nombreuses années sur des bancs expérimentaux dans le but de développer des modèles numériques prédictifs. L’objectif de ces travaux de thèse est la caractérisation expérimentale de deux revêtements abradables du compresseur basse pression – l’AlSi-PE – et haute pression – le Metco 2043 – sur un banc expérimental existant. La configuration adoptée est simplifiée et se dédouane de la dynamique d’aube et du turboréacteur. La caractérisation thermomécanique des deux revêtements de l’étude a été rendue possible grâce à la corrélation des efforts d’interaction, des échauffements produits par le contact et des endommagements induits. Les développements technologiques ont permis de réaliser des essais représentatifs jusqu’à 135 m s−1 et 720 ◦C. Une modélisation semi-analytique basée sur la technique des fonctions de Green a également été mise en place pour estimer la température au contact et les coefficients de répartition du flux thermique dans l’aube et le revêtement abradable. Les résultats numériques ont finalement été corrélés à un essai pilote pour valider l’approche.Reducing gaps between blades and the casing allows an increasing of the aircraft engines effi- ciency. Moreover, blade/casing interactions, mainly due to engine vibrations, may occur. They are localized at the blade tip and may lead to the engine failure. Specific materials called « abradable materials » are used to reduce interactions impact. When an interaction occurs, the abradable ma- terial will be worn preferentialy to the blade and limits the interaction energies. Those materials are studied since many years on experimental devices to develop predictive numerical models. The purpose of this thesis is the experimental characterization of two abradable materials grades from the low-pressure compressor – the AlSi-PE grade – and from the high-pressure compressor – the CoNiCrAlY-hBN grade – on an experimental device. The experimental configuration is simpli- fied and doesn’t take in account the blade’s and casing’s dynamic phenomena. Thermomechanical characterization of two coatings was performed thanks to the correlation between forces, tem- peratures and wear mechanisms. Technological developments allowed representative tests up to 135 m/s and 720 °C. Semi-analytical modeling with Green’s techniques has been used to predict friction temperatures and heat distribution coefficients in the blade and the abradable material. Results have been correlated to an experimental test to approve the model

Performances commerciales de l'Afrique subsaharienne : une diversification nécessaire

(English) This study analyses trade strategies and performances of a sample of seven Sub-Saharan African countries (South Africa, Côte d’Ivoire, Ghana, Madagascar, Mauritius, Nigeria and Senegal), which together represent over two-thirds of Africa’s total exports. Although the poor overall Africa’s trade performance can be explained to a great extent by well known factors (commodity prices, macroeconomic problems, etc.), this does nothing to explain why some countries succeed to increase their exports and not others. This paper attempts to do so, by splitting these countries’ export growth rate during the 1990s, into a demand effect and a competitiveness effect. This allows us to appreciate the impact of specialization on trade performance: if a country is specialised in goods for which there is little world demand, or whose sales prices are falling, its exports will be affected accordingly. According to this breakdown, it is not trade specialisation that explains why certain countries succeeded, but above all their competitiveness, that is their ability to increase their market shares on both traditional and new export products. The analysis also clearly shows that the best performing countries are precisely those which have diversified their exports the most, such as Madagascar (thanks to its export processing zones), South Africa and Ghana. _________________________________ (français) Cette étude analyse les stratégies et les performances commerciales de sept pays d’Afrique subsaharienne (Afrique du Sud, Côte d’Ivoire, Ghana, Madagascar, Maurice, Nigeria et Sénégal) durant les années 1990. Ces pays représentent plus des deux tiers des exportations totales africaines. Bien que les médiocres performances globales de l’Afrique en général puissent être attribuées en grande partie à des facteurs bien connus (baisse du prix des matières premières, problèmes macroéconomiques, etc.), ceci n’explique pas pourquoi certains pays arrivent à accroître leurs exportations et d’autres non. Pour répondre à cette question, on procède à une décomposition comptable de la croissance des exportations de chaque pays entre un effet spécialisation sectorielle et un effet de compétitivité. Le premier effet permet d’évaluer par exemple l’impact d’une baisse des prix ou de la demande pour les secteur s dans lesquels un pays est spécialisé ; le second effet mesure les gains/pertes de parts de marché au niveau de chaque produit traditionnellement ou nouvellement exporté. Cette décomposition montre que les écarts de performances entre pays ne s’expliquent pas par les différences de spécia lisation mais par celles de compétitivité. De manière cohérente, l’analyse menée en termes d’indices de diversification montre que les pays les plus performants sont ceux qui ont réussi à diversifier le plus leurs exportations, à savoir Madagascar (à travers l’essor de ses zones franches), l’Afrique du Sud et le Ghana.

Influence of Risk Factors for Male Infertility on Sperm Protein Composition

Male infertility is a common health problem that can be influenced by a host of lifestyle risk factors such as environment, nutrition, smoking, stress, and endocrine disruptors. These effects have been largely demonstrated on sperm parameters (e.g., motility, numeration, vitality, DNA integrity). In addition, several studies showed the deregulation of sperm proteins in relation to some of these factors. This review inventories the literature related to the identification of sperm proteins showing abundance variations in response to the four risk factors for male infertility that are the most investigated in this context: obesity, diabetes, tobacco smoking, and exposure to bisphenol-A (BPA). First, we provide an overview of the techniques used to identify deregulated proteins. Then, we summarise the main results obtained in the different studies and provide a compiled list of deregulated proteins in relation to each risk factor. Gene ontology analysis of these deregulated proteins shows that oxidative stress and immune and inflammatory responses are common mechanisms involved in sperm alterations encountered in relation to the risk factors

Targeted Analysis of HSP70 Isoforms in Human Spermatozoa in the Context of Capacitation and Motility

HSP70s constitute a family of chaperones, some isoforms of which appear to play a role in sperm function. Notably, global proteomic studies analyzing proteins deregulated in asthenozoospermia, a main cause of male infertility characterized by low sperm motility, showed the dysregulation of some HSP70 isoforms. However, to date, no clear trend has been established since the variations in the abundance of HSP70 isoforms differed between studies. The HSPA2 isoform has been reported to play a key role in fertilization, but its dysregulation and possible relocation during capacitation, a maturation process making the spermatozoon capable of fertilizing an oocyte, is debated in the literature. The aim of the present study was to investigate the fate of all sperm HSP70 isoforms during capacitation and in relation to sperm motility. Using Multiple-Reaction Monitoring (MRM) mass spectrometry, we showed that the relative abundance of all detected isoforms was stable between non-capacitated and capacitated spermatozoa. Immunofluorescence using two different antibodies also demonstrated the stability of HSP70 isoform localization during capacitation. We also investigated spermatozoa purified from 20 sperm samples displaying various levels of total and progressive sperm motility. We showed that the abundance of HSP70 isoforms is not correlated to sperm total or progressive motility.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A Protocol to Assess Insect Resistance to Heat Waves, Applied to Bumblebees (<i>Bombus</i> Latreille, 1802)

<div><p>Insect decline results from numerous interacting factors including climate change. One of the major phenomena related to climate change is the increase of the frequency of extreme events such as heat waves. Since heat waves are suspected to dramatically increase insect mortality, there is an urgent need to assess their potential impact. Here, we determined and compared the resistance to heat waves of insects under hyperthermic stress through their time before heat stupor (THS) when they are exposed to an extreme temperature (40°C). For this, we used a new experimental standardised device available in the field or in locations close to the field collecting sites. We applied this approach on different Arctic, Boreo-Alpine and Widespread bumblebee species in order to predict consequences of heat waves. Our results show a heat resistance gradient: the heat stress resistance of species with a centred arctic distribution is weaker than the heat resistance of the Boreo-Alpine species with a larger distribution which is itself lower than the heat stress resistance of the ubiquitous species.</p></div