Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 290)

This bibliography lists 125 reports, articles and other documents introduced into the NASA scientific and technical information system in October 1986

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 204

This bibliography lists 140 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980

Mathematical models for chemotaxis and their applications in self-organisation phenomena

Chemotaxis is a fundamental guidance mechanism of cells and organisms, responsible for attracting microbes to food, embryonic cells into developing tissues, immune cells to infection sites, animals towards potential mates, and mathematicians into biology. The Patlak-Keller-Segel (PKS) system forms part of the bedrock of mathematical biology, a go-to-choice for modellers and analysts alike. For the former it is simple yet recapitulates numerous phenomena; the latter are attracted to these rich dynamics. Here I review the adoption of PKS systems when explaining self-organisation processes. I consider their foundation, returning to the initial efforts of Patlak and Keller and Segel, and briefly describe their patterning properties. Applications of PKS systems are considered in their diverse areas, including microbiology, development, immunology, cancer, ecology and crime. In each case a historical perspective is provided on the evidence for chemotactic behaviour, followed by a review of modelling efforts; a compendium of the models is included as an Appendix. Finally, a half-serious/half-tongue-in-cheek model is developed to explain how cliques form in academia. Assumptions in which scholars alter their research line according to available problems leads to clustering of academics and the formation of "hot" research topics.Comment: 35 pages, 8 figures, Submitted to Journal of Theoretical Biolog

Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

Aerospace Medicine and Biology. A continuing bibliography (Supplement 226)

This bibliography lists 129 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1981

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 197, September 1979

This bibliography lists 193 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1979

The Oral Tolerance as a Complex Network Phenomenon

Date of Acceptance: 23/05/2015 Funding: MSB acknowledges the Engineering and Physical Sciences Research Council (EPSRC) - UK grant EP/I032606/1. PJM and MD received regular scholarships from the Brazilian the following agency: Higher Education Personnel Training Coordination (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) CAPES http://www.fisica.uepg.br:7080/ppgfisica​/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 331)

This bibliography lists 129 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during December, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Rare event simulation for probabilistic models of T-cell activation

Lipsmeier F. Rare event simulation for probabilistic models of T-cell activation. Bielefeld (Germany): Bielefeld University; 2010.One of the central questions in immunobiology is: How does the immune system reliably distinguish between antigens of our own body and foreign antigens? This ability is critical for our survival. One of the major cell types involved in these decisions are the so called T-cells, which are specialized white blood cells with a detection mechanism that is not fully explained until now. There is not a one to one specificity between T-cells and antigens. T-cells have to be cross-reactive, that is they have to be able to be activated by several antigens. The usual mathematical models in immunobiology are deterministic ones and therefore not applicable to the given problem. We need probabilistic approaches in order to describe the problem properly, because of the huge amount of possible receptor-antigen-combinations and the fact that a given T-cell is not confronted with individual antigens but has to make its decision when being in contact with so called antigen presenting cells (APC) which present a huge amount of antigens on their surface. This thesis deals with the probabilistic modeling and efficient simulation of models which describe the mechanism of T-cell activation and foreign-self discrimination. Because of the complexity of the topic, the first part of the thesis forms a review of the recent experimental findings with regard to T-cell immunology. Afterwards we introduce the already existing first probabilistic model of T-cell activation developed by van den Berg, Rand and Burroughs (BRB). The second part of this thesis is concerned with the simulation and analysis of this model. As T-cell activation is a rare event, that is the probability of T-cell activation is very low, we cannot analyze the model with the usual simple sampling strategies, but rely on the so-called importance sampling approach. With the help of large deviation theory we are able to construct an efficient simulation algorithm, which uses special alternative distributions for sampling for which we can proof asymptotic efficiency. In our analysis of the BRB model we are able to show that it can explain foreign-self discrimination and explain how this comes about in the model. We are also able to show where the defects of the model are, especially with regard to the biological relevance. Consequently, in the third part of this thesis we develop a new model of T-cell activation. One major improvement in this model is, that we are able to integrate negative selection which is a process during T-cell maturation where T-cells that are to self-reactive are induced to die. Again, we have to adapt and develop new simulation algorithms for the analysis of this model. We are then able to show that our new model is able to explain foreign-self discrimination with parameters that are biologically much more plausible than in the BRB model

Aerospace Medicine and Biology: A continuing bibliography, supplement 191

A bibliographical list of 182 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1979 is presented