The impact of mutation and gene conversion on the local diversification of antigen genes in African trypanosomes

Patterns of genetic diversity in parasite antigen gene families hold important information about their potential to generate antigenic variation within and between hosts. The evolution of such gene families is typically driven by gene duplication, followed by point mutation and gene conversion. There is great interest in estimating the rates of these processes from molecular sequences for understanding the evolution of the pathogen and its significance for infection processes. In this study, a series of models are constructed to investigate hypotheses about the nucleotide diversity patterns between closely related gene sequences from the antigen gene archive of the African trypanosome, the protozoan parasite causative of human sleeping sickness in Equatorial Africa. We use a hidden Markov model approach to identify two scales of diversification: clustering of sequence mismatches, a putative indicator of gene conversion events with other lower-identity donor genes in the archive, and at a sparser scale, isolated mismatches, likely arising from independent point mutations. In addition to quantifying the respective probabilities of occurrence of these two processes, our approach yields estimates for the gene conversion tract length distribution and the average diversity contributed locally by conversion events. Model fitting is conducted using a Bayesian framework. We find that diversifying gene conversion events with lower-identity partners occur at least five times less frequently than point mutations on variant surface glycoprotein (VSG) pairs, and the average imported conversion tract is between 14 and 25 nucleotides long. However, because of the high diversity introduced by gene conversion, the two processes have almost equal impact on the per-nucleotide rate of sequence diversification between VSG subfamily members. We are able to disentangle the most likely locations of point mutations and conversions on each aligned gene pair

Feasibility study of the solar scientific instruments for Spacelab/Orbiter

The feasibility and economics of mounting and operating a set of solar scientific instruments in the backup Skylab Apollo Telescope Mount (ATM) hardware was evaluated. The instruments used as the study test payload and integrated into the ATM were: the Solar EUV Telescope/Spectrometer; the Solar Active Region Observing Telescope; and the Lyman Alpha White Light Coronagraph. The backup ATM hardware consists of a central cruciform structure, called the "SPAR', a "Sun End Canister' and a "Multiple Docking Adapter End Canister'. Basically, the ATM hardware and software provides a structural interface for the instruments; a closely controlled thermal environment; and a very accurate attitude and pointing control capability. The hardware is an identical set to the hardware that flow on Skylab

Consensus statement on improving the mental health of high performance athletes

This consensus statement is the product of an international Think Tank on the initiative of the International Society of Sport Psychology. The purpose of the Think Tank was to unify major sport psychology organizations in a discussion of the current status and future challenges of applied and research aspects of athlete mental health. The contributors present six propositions and recommendations to inspire sport organizations and researchers. The propositions are: Mental health is a core component of a culture of excellence; Mental health in a sport context should be better defined; Research on mental health in sport should broaden the scope of assessment; Athlete mental health is a major resource for the whole athletic career and life post-athletic career; The environment can nourish or malnourish athlete mental health; and Mental health is everybody’s business but should be overseen by one or a few specified members. It is recommended that researchers unite to develop a more contextualized definition of athlete mental health and more comprehensive strategies of assessment, as well as join forces with sporting organizations to investigate sustainable elite sport environments and the role of the mental health officer. Sport organizations are advised to recognize athlete mental health as a core component of a healthy elite sport system and a key indicator of their effectiveness, support research initiatives, and to promote the mental health literacy of all their staff while engaging a mental health officer with the responsibility to oversee a support system

The Turkey Ig-like receptor family: identification, expression and function.

The chicken leukocyte receptor complex located on microchromosome 31 encodes the chicken Ig-like receptors (CHIR), a vastly expanded gene family which can be further divided into three subgroups: activating CHIR-A, bifunctional CHIR-AB and inhibitory CHIR-B. Here, we investigated the presence of CHIR homologues in other bird species. The available genome databases of turkey, duck and zebra finch were screened with different strategies including BLAST searches employing various CHIR sequences, and keyword searches. We could not identify CHIR homologues in the distantly related zebra finch and duck, however, several partial and complete sequences of CHIR homologues were identified on chromosome 3 of the turkey genome. They were designated as turkey Ig-like receptors (TILR). Using cDNA derived from turkey blood and spleen RNA, six full length TILR could be amplified and further divided according to the typical sequence features into one activating TILR-A, one inhibitory TILR-B and four bifunctional TILR-AB. Since the TILR-AB sequences all displayed the critical residues shown to be involved in binding to IgY, we next confirmed the IgY binding using a soluble TILR-AB1-huIg fusion protein. This fusion protein reacted with IgY derived from various gallinaceous birds, but not with IgY from other bird species. Finally, we tested various mab directed against CHIR for their crossreactivity with either turkey or duck leukocytes. Whereas no staining was detectable with duck cells, the CHIR-AB1 specific mab 8D12 and the CHIR-A2 specific mab 13E2 both reacted with a leukocyte subpopulation that was further identified as thrombocytes by double immunofluorescence employing B-cell, T-cell and thrombocyte specific reagents. In summary, although the turkey harbors similar LRC genes as the chicken, their distribution seems to be distinct with predominance on thrombocytes rather than lymphocytes

Component Hiding Using Identification and Boundary Blurring Techniques

Protecting software from adversarial attacks is extremely important for DoD technologies. When systems are compromised, the possibility exists for recovery costing millions of dollars and countless labor hours. Circuits implemented on embedded systems utilizing FPGA technology are the result of downloading software for instantiating circuits with specific functions or components. We consider the problem of component hiding a form of software protection. Component identification is a well studied problem. However, we use component identification as a metric for driving the cost of reverse engineering to an unreasonable level. We contribute to protection of software and circuitry by implementing a Java based component identification tool. With this tool, we can characterize time required for carrying out adversarial attacks on unaltered boolean circuitry. To counter component identification methods we utilize boundary blurring techniques which are either semantic preserving or semantic changing in order to prevent component identification methods. Furthermore, we will show these techniques can drive adversarial cost to unreasonable levels preventing compromise of critical systems