295 research outputs found
Particle types and sources associated with LDEF
The particulate contamination history of the Long Duration Exposure Facility (LDEF) can be resolved by careful analysis of particle types, the LDEF time line, evidence of the relationship between particles and the surface of the LDEF, and a consideration of probable sources. This work is far from complete but was initiated as part of the characterization of the condition of experimental trays that were returned to principle investigators for their analysis. The work presented in this photo-essay is continuing and will be updated in subsequent reports to NASA and at future technical meetings
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
Likelihood-Free Dynamical Survival Analysis applied to the COVID-19 epidemic in Ohio
The Dynamical Survival Analysis (DSA) is a framework for modeling epidemics based on mean field dynamics applied to individual (agent) level history of infection and recovery. Recently, the Dynamical Survival Analysis (DSA) method has been shown to be an effective tool in analyzing complex non-Markovian epidemic processes that are otherwise difficult to handle using standard methods. One of the advantages of Dynamical Survival Analysis (DSA) is its representation of typical epidemic data in a simple although not explicit form that involves solutions of certain differential equations. In this work we describe how a complex non-Markovian Dynamical Survival Analysis (DSA) model may be applied to a specific data set with the help of appropriate numerical and statistical schemes. The ideas are illustrated with a data example of the COVID-19 epidemic in Ohio
Heart Rate during Conflicts Predicts Post-Conflict Stress-Related Behavior in Greylag Geese
Background: Social stressors are known to be among the most potent stressors in group-living animals. This is not only manifested in individual physiology (heart rate, glucocorticoids), but also in how individuals behave directly after a conflict. Certain ‘stress-related behaviors ’ such as autopreening, body shaking, scratching and vigilance have been suggested to indicate an individual’s emotional state. Such behaviors may also alleviate stress, but the behavioral context and physiological basis of those behaviors is still poorly understood. Methodology/Principal Findings: We recorded beat-to-beat heart rates (HR) of 22 greylag geese in response to agonistic encounters using fully implanted sensor-transmitter packages. Additionally, for 143 major events we analyzed the behavior shown by our focal animals in the first two minutes after an interaction. Our results show that the HR during encounters and characteristics of the interaction predicted the frequency and duration of behaviors shown after a conflict. Conclusions/Significance: To our knowledge this is the first study to quantify the physiological and behavioral responses to single agonistic encounters and to link this to post conflict behavior. Our results demonstrate that ‘stress-related behaviors’ are flexibly modulated by the characteristics of the preceding aggressive interaction and reflect the individual’s emotional strain, which is linked to autonomic arousal. We found no support for the stress-alleviating hypothesis, but we propose tha
Social and environmental factors modulate leucocyte profiles in free-living Greylag geese (Anser anser)
Background. Blood parameters such as haematocrit or leucocyte counts are indicators of immune status and health, which can be affected, in a complex way, by exogenous as well as endogenous factors. Additionally, social context is known to be among the most potent stressors in group living individuals, therefore potentially influencing haematological parameters. However, with few exceptions, this potential causal relationship received only moderate scientific attention.
Methods. In a free-living and individually marked population of the highly social and long-lived Greylag goose, Anser anser, we relate variation in haematocrit (HCT), heterophils to lymphocytes ratio(H/L) and blood leucocyte counts to the following factors: intrinsic (sex, age, raising condition, i.e. goose- or hand-raised), social (pair-bond status, pair-bond duration and parental experience) and environmental (biologically relevant periods, ambient temperature) factors. Blood samples were collected repeatedly from a total of 105 focal birds during three biologically relevant seasons (winter flock, mating season, summer).
Results. We found significant relationships between haematological parameters and social as well as environmental factors. During the mating season, unpaired individuals had higher HCT compared to paired and family individuals and this pattern reversed in fall. Similarly, H/L ratio was positively related to pair-bond status in a seasonally dependent way, with highest values during mating and successful pairs had higher H/L ratio than unsuccessful ones. Also, absolute number of leucocytes tended to vary depending of raising condition in a seasonally dependent way.
Discussion. Haematology bears a great potential in ecological and behavioural studies on wild vertebrates. In sum we found that HTC, H/L ratio and absolute number of leucocytes are modulated by social factors and conclude that they may be considered valid indicators of individual stress load
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Measuring societal awareness of the rural agrarian landscape: indicators and scale issues
The work presented in this report is part of the effort to define the landscape state and diversity indicator in the
frame of COM (2006) 508 “Development of agri-environmental indicators for monitoring the integration of
environmental concerns into the common agricultural policy”. The Communication classifies the indicators
according to their level of development, which, for the landscape indicator is “in need of substantial
improvements in order to become fully operational”. For this reason a full re-definition of the indicator has been
carried out, following the initial proposal presented in the frame of the IRENA operation (“Indicator Reporting on
the Integration of Environmental Concerns into Agricultural Policy”). The new proposal for the landscape state
and diversity indicator is structured in three components: the first concerns the degree of naturalness, the
second landscape structure, the third the societal appreciation of the rural landscape. While the first two
components rely on a strong bulk of existing literature, the development of the methodology has made evident
the need for further analysis of the third component, which is based on a newly proposed top-down approach.
This report presents an in-depth analysis of such component of the indicator, and the effort to include a social
dimension in large scale landscape assessment
Measuring societal awareness of the rural agrarian landscape: indicators and scale issues
The work presented in this report is part of the effort to define the landscape state and diversity indicator in the frame of COM (2006) 508 “Development of agri-environmental indicators for monitoring the integration of environmental concerns into the common agricultural policy”. The Communication classifies the indicators according to their level of development, which, for the landscape indicator is “in need of substantial improvements in order to become fully operational”. For this reason a full re-definition of the indicator has been carried out, following the initial proposal presented in the frame of the IRENA operation (“Indicator Reporting on the Integration of Environmental Concerns into Agricultural Policy”). The new proposal for the landscape state and diversity indicator is structured in three components: the first concerns the degree of naturalness, the second landscape structure, the third the societal appreciation of the rural landscape. While the first two components rely on a strong bulk of existing literature, the development of the methodology has made evident the need for further analysis of the third component, which is based on a newly proposed top-down approach. This report presents an in-depth analysis of such component of the indicator, and the effort to include a social dimension in large scale landscape assessment.JRC.H.4-Monitoring Agricultural Resource
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
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