Protention and retention in biological systems

This paper proposes an abstract mathematical frame for describing some features of cognitive and biological time. We focus here on the so called "extended present" as a result of protentional and retentional activities (memory and anticipation). Memory, as retention, is treated in some physical theories (relaxation phenomena, which will inspire our approach), while protention (or anticipation) seems outside the scope of physics. We then suggest a simple functional representation of biological protention. This allows us to introduce the abstract notion of "biological inertia".Comment: This paper was made possible only as part of an extended collaboration with Francis Bailly (see references), a dear friend and "ma\^itre \'a penser", who contributed to the key ideas. Francis passed away in february 2008: we continue here our inspiring discussions and joint wor

Impact of controlled neonicotinoid exposure on bumblebees in a realistic field setting

1. Pesticide exposure has been implicated as a contributor to insect pollinator declines. In social bees, which are crucial pollination service providers, the effect of low-level chronic exposure is typically non-lethal leading researchers to consider whether exposure induces sub-lethal effects on behaviour and whether such impairment can affect colony development. 2. Studies under laboratory conditions can control levels of pesticide exposure and elucidate causative effects, but are often criticised for being unrealistic. In contrast, field studies can monitor bee responses under a more realistic pesticide exposure landscape; yet typically such findings are limited to correlative results, and can lack true controls or sufficient replication. We attempt to bridge this gap by exposing bumblebees to known amounts of pesticides when colonies are placed in the field. 3. Using 20 bumblebee colonies, we assess the consequences of exposure to the neonicotinoid clothianidin, provided in sucrose at a concentration of five parts per billion, over five weeks. We monitored foraging patterns and pollen collecting performance from 3282 bouts using either a non-invasive photographic assessment, or by extracting the pollen from returning foragers. We also conducted a full colony census at the beginning and end of the experiment. 4. In contrast to studies on other neonicotinoids, showing clear impairment to foraging behaviours, we detected only subtle changes to patterns of foraging activity and pollen foraging during the course of the experiment. However, our colony census measures showed a more pronounced effect of exposure, with fewer adult workers and sexuals in treated colonies after five weeks. 5. Synthesis and applications. Pesticide induced impairments on colony development and foraging could impact on the pollination service that bees provide. Therefore our findings, that bees show subtle changes in foraging behaviour and reductions in colony size after exposure to a common pesticide, has important implications and helps to inform the debate over whether the benefits of systemic pesticide application to flowering crops outweigh the costs. We propose that our methodology is an important advance to previous semi-field methods and should be considered when considering improvements to current ecotoxicological guidelines for pesticide risk assessment

MAELIA-OWM: agro-environmental and socio-economic modelling and assessment tool for territorial management of organic resources

The use of organic wastes (OW) as fertilizers has various positive effects on ecosystem services such as soil fertility, climate regulation and soil biodiversity. OW use can also have negative effects such as increased nitrogen leaching and heavy metals accumulation. Moreover, OW can affect different aspects of a farming system (workload, yields, fertilizing costs). Optimizing OW management at local level requires an approach that would consider their characteristics (e.g. organic matter stability, fertilizing value), climate, soil and cropping system heterogeneities as well as the multiple feedback relationships that link the system components. OW territorial management could benefit from an Integrated Assessment and Modelling (IAM) tool allowing stakeholders to consider biophysical and socio-economic processes from field to territorial level. To reach this objective, we adapted the IAM MAELIA platform developed for modelling and simulating social-agro-ecosystems at local/regional level. MAELIA-OWM (Organic Wastes Management) provides solutions for assessing ecosystem services, economic and social impacts of scenarios regarding territorial OWM, agricultural activities, agro-environmental policies and climate changes. MAELIA is based on a set of validated models suitable for the simulation of various biophysical contexts. MAELIA-OWM is applied on the Versailles Plain, France (240 km²). This territory is characterized by a high availability but low usage of urban OW. MAELIA-OWM requires multiple sets of spatial data describing the territorial settings (e.g. climate grid, soil map, Land Parcel Identification System) and the agricultural practices of the study area. Different prospective scenarios (greater use of available OW, cover cropping) were compared to a baseline scenario (little use of OW, current practices) through a set of agro-environmental and socio-economic criteria (GHG emissions, carbon storage, nitrogen leaching, gross margins and workload). Actual developments of the model are dedicated to the implementation of an OW-chain model that will consider organic wastes production, transformation and transport

Can one believe in the results of science insofar as doubt is one of the first qualities of the scientist?

Le doute pratiqué par les hommes de sciences n’est pas celui que proposent les sceptiques aux yeux de qui nos savoirs sont des illusions liées à notre crédulité. Les scientifiques ont la conviction que le monde est intelligible et que l’on peut y accéder de façon efficace en mettant en œuvre une méthode critique basée sur l’approche empirique, l’observation, l’expérimentation, l’induction et la mise en équation mathématiques des résultats. Cette pratique rigoureuse permet à l’homme d’anticiper de mieux en mieux la manifestation de certains phénomènes, donc d’augmenter notre confiance vitale et notre sentiment de sécurité face à un monde improbable auquel les êtres vivants sont confrontés.The role of vitamin D in the organism in general and on the liver particularly, firstly depends on the genetic heritage and also on environmental factors, especially sun exposure and in lesser measure on dietary intakes. The main part of vitamin D is related to phosphocalcic and bone metabolism but, as it affects the activity of more than 200 genes, it is also involved in nonspecific acquired immunity in the cardiovascular system, liver and infections. Regarding the liver, deficiency is frequently observed in chronic hepatic diseases and severe deficiency might be involved in the worsening of liver condition. Clinical trials are nevertheless necessary to assess the interest, the efficiency and the optimal mode of supplementation. The HAS reminded in October 2013 the rules of good practice and limits the dosage of vitamin D to well-defined cases: diagnosis of rickets and osteomalacia, some drug prescription against osteoporosis, adult kidney transplant or after obesity surgery, elderly who are victims of repeated falls and eventually at high risk of fractures. In all other situations, currently available data is inadequate to determine the clinical usefulness of vitamin D dosage. Finally, taking into account the frequency of the deficit, it might be interesting to redefine, in a near future, the thresholds of normality and review the recommended daily intake

Génération d’environnements pour la simulation comportementale de vecteurs épidémiques : application à Aedes aegypti, vecteur de la dengue et du virus zika

Le moustique Aedes aegypti est le vecteur principal de la dengue et du virus Zika. Il est surtout présent dans les villes des zones tropicales et intertropicales d’Afrique, d’Amérique et d’Asie (Rodhain 1996). À moyen terme, les vaccins en cours de développement contribueront probablement au recul de ces maladies. Néanmoins, l’émergence ou la réémergence de maladies transmises par ces moustiques (comme la récente réémergence du Zika en Amérique Latine) font des mesures anti-vectorielles des é..

Les cercles fonctionnels de von Uexküll en tant que modes existentiels

L’idée de naturaliser la phénoménologie peut paraître comme une réduction de la perspective transcendantale au rêve d’une science de la nature animée du désir de connaître le réel tel qu’il est. Or, les dérives du positivisme ont montré l’intérêt qu’il y a, pour le scientifique, d’un regard aux conditions subjectives a priori de la libido sciendi. Faut-il rappeler von Uexküll : les vivants se comportent à l’égard de leur environnement comme des sujets équipés pour s’y orienter activement et assurer leur existence ? Vues sous cet angle, les sciences de la nature apparaissent dès lors pour ce qu’elles sont, – des sciences de l’homme !The idea of naturalizing phenomenology might evoque that of reducing the transcendantal viewpoint to the dream of a natural science anxious to know reality as it is. Thus, the former lapses of positivism showed how important it is for the scientist to look at the a priori subjective conditions of libido sciendi. Let’s remember von Uexküll: living beings behave in their environment as agents provided with the necessary means to orient themselves and ensure their living in it. Considered from the same point of view, natural sciences appear as what they are: nothing other than sciences of man

Contamination of wild plants near neonicotinoid seed-treated crops, and implications for non-target insects

Neonicotinoid insecticides are commonly-used as seed treatments on flowering crops such as oilseed rape. Their persistence and solubility in water increase the chances of environmental contamination via surface-runoff or drainage into areas adjacent to the crops. However, their uptake and fate into non-target vegetation remains poorly understood. In this study, we analysed samples of foliage collected from neonicotinoid seed-treated oilseed rape plants and also compared the levels of neonicotinoid residues in foliage (range: 1.4 – 11 ng/g) with the levels found in pollen collected from the same plants (range: 1.4 – 22 ng/g). We then analysed residue levels in foliage from non-target plants growing in the crop field margins (range: ≤ 0.02 – 106 ng/g). Finally, in order to assess the possible risk posed by the peak levels of neonicotinoids that we detected in foliage for farmland phytophagous and predatory insects, we compared the maximum concentrations found against the LC50 values reported in the literature for a set of relevant insect species. Our results suggest that neonicotinoid seed-dressings lead to widespread contamination of the foliage of field margin plants with mixtures of neonicotinoid residues, where levels are very variable and discontinuous, but sometimes overlap with lethal concentrations reported for some insect species. Understanding the distribution of pesticides in the environment and their potential effects on biological communities is crucial to properly assess current agricultural management and schemes with biodiversity conservation aims in farmland

MAELIA-OWM: agro-environmental and socioeconomic modelling and assessment tool for territorial management of organic resources

The use of organic wastes (OW) as fertilizers has various positive effects on ecosystem services such as soil fertility, climate regulation and soil biodiversity. OW use can also have negative effects such as increased nitrogen leaching and heavy metals accumulation. Moreover, OW can affect different aspects of a farming system (workload, yields, fertilizing costs). Optimizing OW management at local level requires an approach that would consider their characteristics (e.g. organic matter stability, fertilizing value), climate, soil and cropping system heterogeneities as well as the multiple feedback relationships that link the system components. OW territorial management could benefit from an Integrated Assessment and Modelling (IAM) tool allowing stakeholders to consider biophysical and socio-economic processes from field to territorial level. To reach this objective, we adapted the IAM MAELIA platform developed for modelling and simulating social-agro-ecosystems at local/regional level. MAELIA-OWM (Organic Wastes Management) provides solutions for assessing ecosystem services, economic and social impacts of scenarios regarding territorial OWM, agricultural activities, agro-environmental policies and climate changes. MAELIA is based on a set of validated models suitable for the simulation of various biophysical contexts. MAELIA-OWM is applied on the Versailles Plain, France (240 km²). This territory is characterized by a high availability but low usage of urban OW. MAELIA-OWM requires multiple sets of spatial data describing the territorial settings (e.g. climate grid, soil map, Land Parcel Identification System) and the agricultural practices of the study area. Different prospective scenarios (greater use of available OW, cover cropping) were compared to a baseline scenario (little use of OW, current practices) through a set of agro-environmental and socio-economic criteria (GHG emissions, carbon storage, nitrogen leaching, gross margins and workload). Actual developments of the model are dedicated to the implementation of an OW-chain model that will consider organic wastes production, transformation and transport