86,534 research outputs found
Rare event simulation in immunobiology
No full textBaake E, Lipsmeier F. Rare event simulation in immunobiology. In: Proceedings of the 7th International Workshop on Rare Event Simulation RESIM 2008, Rennes, France. 2008
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Rare Event Simulation for T-cell Activation
No full textLipsmeier F, Baake E. Rare Event Simulation for T-cell Activation. JOURNAL OF STATISTICAL PHYSICS. 2009;134(3):537-566.The problem of statistical recognition is considered, as it arises in immunobiology, namely, the discrimination of foreign antigens against a background of the body's own molecules. The precise mechanism of this foreign-self-distinction, though one of the major tasks of the immune system, continues to be a fundamental puzzle. Recent progress has been made by van den Berg, Rand, and Burroughs (J. Theor. Biol. 209:465-486, 2001), who modelled the probabilistic nature of the interaction between the relevant cell types, namely, T-cells and antigen-presenting cells (APCs). Here, the stochasticity is due to the random sample of antigens present on the surface of every APC, and to the random receptor type that characterises individual T-cells. It has been shown previously (van den Berg et al. in J. Theor. Biol. 209:465-486, 2001; Zint et al. in J. Math. Biol. 57:841-861, 2008) that this model, though highly idealised, is capable of reproducing important aspects of the recognition phenomenon, and of explaining them on the basis of stochastic rare events. These results were obtained with the help of a refined large deviation theorem and were thus asymptotic in nature. Simulations have, so far, been restricted to the straightforward simple sampling approach, which does not allow for sample sizes large enough to address more detailed questions. Building on the available large deviation results, we develop an importance sampling technique that allows for a convenient exploration of the relevant tail events by means of simulation. With its help, we investigate the mechanism of statistical recognition in some depth. In particular, we illustrate how a foreign antigen can stand out against the self background if it is present in sufficiently many copies, although no a priori difference between self and nonself is built into the model
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
Maine author Franklin F. Gould recalls his first glimpse of the outside world
No full textMaine author Franklin F. Gould recalls his first glimpse of the outside world as he relates how, as a young farm boy in the late 1800\u27s, he drove his father\u27s horses on an errand to an icebound river
Rare event simulation for probabilistic models of T-cell activation
No full textLipsmeier 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
Mapping the Discipline of the Olympic Games An Author-Cocitation Analysis
No full textThe authors conducted an author cocitation analysis on prominent authors writing about the Olympics during the 1990s. Author cocitation is an established bibliometric technique that can be used to measure the relative similarities of topics written about by the cited authors. This enables a visual representation of the “intellectual space” of the discipline, in this case the Olympics, to be created for the period under review. So core and peripheral research areas are identified, along with their major contributors. The representation appears as a two-dimensional cluster-enhanced map. Subject expertise was then applied to the results to place labels on the generated clusters of authors and their topics
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