Quantification of contaminants associated with LDEF

The quantification of contaminants on the Long Duration Exposure Facility (LDEF) and associated hardware or tools is addressed. The purpose of this study was to provide a background data base for the evaluation of the surface of the LDEF and the effects of orbital exposure on that surface. This study necessarily discusses the change in the distribution of contaminants on the LDEF with time and environmental exposure. Much of this information may be of value for the improvement of contamination control procedures during ground based operations. The particulate data represents the results of NASA contractor monitoring as well as the results of samples collected and analyzed by the authors. The data from the tapelifts collected in the Space Shuttle Bay at Edwards Air Force Base and KSC are also presented. The amount of molecular film distributed over the surface of the LDEF is estimated based on measurements made at specific locations and extrapolated over the surface area of the LDEF. Some consideration of total amount of volatile-condensible materials available to form the resultant deposit is also presented. All assumptions underlying these estimates are presented along with the rationale for the conclusions. Each section is presented in a subsection for particles and another for molecular films

Migration and generation of contaminants from launch through recovery: LDEF case history

It is possible to recreate the contamination history of the Long Duration Exposure Facility (LDEF) through an analysis of its contaminants and selective samples that were collected from surfaces with better documented exposure histories. This data was then used to compare estimates based on monitoring methods that were selected for the purpose of tracking LDEF's exposure to contaminants. The LDEF experienced much more contamination than would have been assumed based on the monitors. Work is still in progress but much of what was learned so far is already being used in the selection of materials and in the design of systems for space. Now experiments are being prepared for flight to resolve questions created by the discoveries on the LDEF. A summary of what was learned about LDEF contaminants over the first year since recovery and deintegration is presented. Over 35 specific conclusions in 5 contamination related categories are listed

Persistence Effects in Labor Force Participation

This paper examines empirically two facets of labor force participation dynamics that imply quite different interpretations of labor market fluctuations. The first, which underlies equilibrium business cycle models, is that workers time their participation to coincide with periods of high real wages. The second, which implies the existence of involuntary unemployment during cyclical downturns, is that workers' current labor force status is heavily influenced by their work experience in the recent past. The authors' results suggest that these persistence effects are a key feature of labor force behavior, particularly for teenagers, adult women, and older men. In contrast, very little evidence could be found to support the intertemporal substitution hypothesis.

Decoding of cognitive processes involved in the continuous performance task

Decoding of electroencephalogram brain representations is a powerful data driven technique to assess the stream of cognitive information processing. It could promote a more thorough understanding of cognitive control networks. For many years, the continuous performance task has been utilized to investigate impaired proactive and reactive cognitive functions. So far, mainly task performance and univariate electroencephalogram were involved in such investigations. In this study, we benefit from multi-variate pattern analysis of continuous performance task variations to provide a more complete spatio-temporal outline of information processing flow involved in sustained and transient attention and response preparation. Besides effects that are well in line with previous EEG research but could be described in more spatial and temporal detail by the used methods, our results could suggest the presence of a higher order feedback control system when expectations are violated. Such a feedback control is related to modulations of behavior both intra- and inter-individually

Removing the cardiac field artefact from the EEG using neural network regression.

When EEG recordings are used to reveal interactions between central-nervous and cardiovascular processes, the cardiac field artifact (CFA) poses a major challenge. Because the electric field generated by cardiac activity is also captured by scalp electrodes, the CFA arises as a heavy contaminant whenever EEG data are analyzed time-locked to cardio-electric events. A typical example is measuring stimulus-evoked potentials elicited at different phases of the cardiac cycle. Here, we present a nonlinear regression method deploying neural networks that allows to remove the CFA from the EEG signal in such scenarios. We train neural network models to predict R-peak centered EEG episodes based on the ECG and additional CFA-related information. In a second step, these trained models are used to predict and consequently remove the CFA in EEG episodes containing visual stimulation occurring time-locked to the ECG. We show that removing these predictions from the signal effectively removes the CFA without affecting the intertrial phase coherence of stimulus-evoked activity. In addition, we provide the results of an extensive grid search suggesting a set of appropriate model hyperparameters. The proposed method offers a replicable way of removing the CFA on the single-trial level, without affecting stimulus-related variance occurring time-locked to cardiac events. Disentangling the cardiac field artifact (CFA) from the EEG signal is a major challenge when investigating the neurocognitive impact of cardioafferent traffic by means of the EEG. When stimuli are presented time-locked to the cardiac cycle, both sources of variance are systematically confounded. Here, we propose a regression-based approach deploying neural network models to remove the CFA from the EEG. This approach effectively removes the CFA on a single-trial level and is purely data-driven, providing replicable results

Les systèmes agroalimentaires et les courts-circuits dans les régions métropolitaines européennes

Feeding the city is an issue of increasing importance because of the capabilities of urban and peri-urban agri-food systems. In the metropolitan food system a dense urban core with a high food demand, interacts with vaste peri-urban and rural areas that can help in satisfying those needs. This paper proposes a tool for the definition of the metropolitan area and for the analysis of agri-food demand and supply in the same area.Nourrir la m\ue9tropole est un enjeu d'importance croissante en raison des capacit\ue9s des syst\ue8mes agroalimentaires p\ue9riurbaines. Dans le syst\ue8me alimentaire m\ue9tropolitain un noyau urbain plus dense avec une grande demande de bien alimentaires, interagit avec des zones p\ue9riurbaines et rurales qui peuvent contribuer \ue0 r\ue9pondre \ue0 ces besoins. Cet article propose un outil pour la d\ue9finition de la zone m\ue9tropolitaine et pour l'analyse de la demande et de l'offre dans cette zone

Metropolitan Foodsheds as Spatial References for a Landscape-Based Assessment of Regional Food Supply

The Food Planning and Innovation for Sustainable Metropolitan Regions (FOODMETRES) project strives to assess the environmental and socioeconomic impacts of food chains, with regard to the spatial, logistical, and resource dimensions of growing food as well as the questions of food safety and quality as key assets for food planning and governance. Recognizing that food production and consumption are not only linked via food chains in a physical–logistic way, but above all via value chains of social acceptance, FoodMetres is designed to combine quantitative and evidence-based research principles with qualitative and discursive methods, in order to address the wider dimensions of food chains in the context of metropolitan agro-systems. One of the research assets is to assess the location and amount of agriculturally productive land within reach of urban centers, to supply metropolitan populations with regionally grown food. For this purpose, we have developed an accessibility approach that is specifically designed to examine the potential of Metropolitan Agro-Food Systems (MAS) to feed urban populations. Taking into account data on transport infrastructure and land cover as well as the protection status of land, this paper highlights the results for the test cases of Ljubljana, Berlin, London, Milano, and Rotterdam

Socially-mediated arousal and contagion within domestic chick broods

Emotional contagion – an underpinning valenced feature of empathy – is made up of simpler, potentially dissociable social processes which can include socially-mediated arousal and behavioural/physiological contagion. Previous studies of emotional contagion have often conflated these processes rather than examining their independent contribution to empathic response. We measured socially-mediated arousal and contagion in 9-week old domestic chicks (n = 19 broods), who were unrelated but raised together from hatching. Pairs of observer chicks were exposed to two conditions in a counterbalanced order: air puff to conspecifics (AP) (during which an air puff was applied to three conspecifics at 30 s intervals) and control with noise of air puff (C) (during which the air puff was directed away from the apparatus at 30 s intervals). Behaviour and surface eye temperature of subjects and observers were measured throughout a 10-min pre-treatment and 10-min treatment period. Subjects and observers responded to AP with increased freezing, and reduced preening and ground pecking. Subjects and observers also showed reduced surface eye temperature - indicative of stress-induced hyperthermia. Subject-Observer behaviour was highly correlated within broods during both C and AP conditions, but with higher overall synchrony during AP. We demonstrate the co-occurrence of socially-mediated behavioural and physiological arousal and contagion; component features of emotional contagion