Academic literature on the topic 'STK'

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, September 2003.<br>Thesis advisor(s): Alex Bordetsky, Rex Buddenberg. Includes bibliographical references (p. 45). Also available online.

The aim of this thesis is to analyse a business model that is defined in two ways: company client and company company. The main point is ensuring of vehicle and emission testing of cars. In the first case, car owners are the clients, and in the second case, car repair shops are the clients. The theoretical part includes definitions of terms and descriptions of individual analyses and serves as a basis for the practical part where we can find internal and external analyses as well as descriptions of both forms of the business model. The outcomes of the analyses are then used to create a SWOT matrix. The conclusion of the thesis contains an evaluation of the data and results of all analyses, which can present a useful tool when deciding about any further development of the business idea.

The master’s thesis goal is construction-technological project of the "Technical inspection station for trucks" in the city of Olomouc. The goal is rationaly propose preparation and organization of the main building construction. The thesis includes design of site equipment, budget, schedule, main construction machines, construction stages, cash-flow assessment and technological prescription for bored piles.

The GPS data from Challenging Mini-satellite Payload (CHAMP) is used for its orbit determination for the epoch day of January 1st 2002.  The orbit of CHAMP is computed from the GPS data and ionospheric effects are removed by frequency combination. Further, the orbits of CHAMP for the same epoch day are computed using the satellite tool kit (STK) employing simplified general perturbations (SGP4) and a high precision orbit propagator (HPOP). Results from both techniques (GPS computed orbit and STK computed orbit) are compared. Furthermore, orbits computed using GPS data are also compared with jet propulsion laboratory’s published CHAMP spacecraft orbit and we have found that root mean square difference in ECEF position X component is below 0.01km other than some spikes at poles. The standard deviation of the difference in ECEF position X coordinate is 11.7m. The accuracy of our computed satellite positions (using GPS data) is about 12 metres for other than polar areas. However there are some occasional spikes, especially at poles, having maximum errors (about 0.055 km).

The StkF protein of Salmonella enterica serovar Paratyphi A, a putative adhesion-associated protein, was used to develop a candidate adhesin-based vaccine against Salmonella infections, particularly S. Paratyphi A-associated enteric fever. Subcutaneous immunisation of BALB/c mice with recombinant StkF (rStkF) showed that this protein was strongly immunogenic as revealed by the presence of high-titre (1:50,000) anti-StkF antibody in sera from immunized mice. Furthermore, as IgG1 was the major antibody isotype induced, it would appear that rStkF generates a strong Th2-type humoral immune response. The induction of a Th2-dominant immune response was further confirmed by splenocyte-associated cytokine profile analysis which demonstrated greater up-regulation of IL-4 than that of IFN-γ or IL-12-p70. In terms of the protective potential of this antigen, in vitro assays demonstrated that StkF-specific murine antiserum markedly enhanced opsonophagocytosis-mediated uptake of StkF-expressing Salmonella bacteria by human neutrophils. Augmented antibody-specific complement-mediated lysis targeting StkF-expressing Salmonella specifically was also shown. These data suggest a likely direct contribution of StkF-specific antibodies to in vivo killing and clearance of Salmonella and strongly support further investigation of StkF as a potential Salmonella vaccine candidate. BlastN-based interrogation of the NCBI bacterial genome database and PCR investigation of a larger set of strains has shown that the S. Paratyphi A stkF gene and/or the whole stk fimbrial gene cluster is carried by ~1/3 of examined Salmonella serovars. Additionally, bioinformatics and phenotypic characterisation has revealed that the stk fimbrial operon belongs to the chaperone/usher-γ4-fimbrial clade and that it encodes a mannose-sensitive haemagglutinating fimbrial structure. The latter trait is typical of type 1 fimbriae. ELISAs based on rStkF, rStaF and rSipA showed variable sensitivity and specificity for the serodiagnosis of invasive Salmonella infections depending on the particular UK or region-specific cut off applied for each antigen. Further refinement and/or merging of these assays may allow for development of simple and cost effective tests with higher sensitivity and/or specificity than the Widal test. Importantly, despite some minor reactivity with serum from patients with other Gram-negative bacterial infections, the rStkF-based ELISA exhibited no reactivity with serum from patients with dengue fever supporting its potential as a discriminatory diagnostic tool between fevers caused by S. Paratyphi A and dengue virus.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2016.<br>Environmental remediation of organic and inorganic contaminants such as hydrocarbons has been a research focus area of interest. Chemical surfactants have been extensively used for the remediation of contaminated sites for immobilisation of hydrocarbons from environmental matrices. The focus has been on the impact of chemical surfactants on the environment. These petroleum-based chemical surfactants have raised serious environmental concerns as: 1) they are toxic, 2) they deteriorate the environment owing to their non-biodegradability, 3) they are costly, and 4) most are not intended for environmental applications. As such, alternatives had to be found to mitigate concerns associated with the application of such synthetic surfactants in bioremediation. Biosurfactants produced by microorganisms are a potential alternative to these synthetic surfactants. They have minimal environmental impact, are biodegradable and can withstand extreme conditions. However, biosurfactants are associated with high production costs and low production yield. Currently, large-scale production of biosurfactants cannot be achieved. Most research focuses on improving production yield which will contribute to the reduction in production costs. A lichenysin lipopeptide biosurfactant producing Bacillus sp., which grew exclusively on Beta vulgaris agrowaste, was identified. The microorganism was found to be an effective emulsifier for high molecular weight hydrocarbons such as, lubricant oil and diesel. The aim of this study was to improve biosurfactant production yield from this Bacillus sp., including emulsification efficacy by optimising fermentation conditions by supplementing the broth with biocompatible nanoparticles synthesised using a green chemistry approach with B. vulgaris (B. vulgaris) extracts. This study also aimed at reducing production costs by using B. vulgaris agrowaste exclusively as the production medium, both for the biosurfactant and the nanoparticles.

Myxococcus xanthus, a Gram-negative bacterium with a developmental cycle, displays a type IV pili (TFP) mediated surface motility known as social (S) gliding. Beside the polarly localized TFP, the fibril or extracellular polysaccharide (EPS) is also required for S-motility to function. It is proposed that S-motility, along with the related bacterial twitching motility in other species, is powered by TFP retraction. EPS is proposed to anchor and trigger such retractions in M. xanthus. EPS production is known to be regulated by TFP and the Dif signal transduction pathway. Two genetic screens were performed previously to identify additional genes important for EPS production. The first was for the isolation of pilA suppressors, the second for the identification of mutants underproducing EPS in a difA suppressor background. Both screens identified transposon insertions at the stk locus. In particular, StkA, a DnaK homolog, was identified as a possible negative regulator of EPS production by a stkA transposon insertion that suppressed a pilA mutation. A stkB transposon insertion was found to have diminished EPS production in a difA suppressor background. In this study, in-frame deletion mutants of the five genes at the stk locus, stkY, stkZ, stkA, stkB and stkC, were constructed and examined. In addition, mutations of rbp and bskL, two genes downstream of the stk locus, were constructed. Like transposon insertions, the stkA in-frame deletion resulted in overproduction of EPS. The stkB and to a less extent the stkC mutants underproduced EPS. Mutations in the other genes had no obvious effects on EPS production. Genetic epistasis suggests that StkA functions downstream of TFP and upstream of the Dif sensory proteins in EPS regulation in M. xanthus. Epistasis analysis involving stkB was inconclusive. It is unresolved whether StkB plays a role in the biosynthesis or the regulation of EPS production in M. xanthus.<br>Master of Science

We are in an era of massive spending cuts in educational institutions, aerospace companies and governmental entities. Educational institutions are pursuing more training for less money, aerospace companies are reducing the cost of gaining ight heritage and the government is cutting budgets and their response times. Organizations are accomplishing this improved efficiency by moving away from large-scale satellite projects and developing pico and nanosatellites following the CubeSat specifications. One of the major challenges of developing satellites to the standard CubeSat mission requirements is meeting the exceedingly tight power, data and communication constraints. A MATLAB toolbox was created to assist the CubeSat community with understanding these restrictions, optimizing their systems, increasing mission success and decreasing the time building to these initial requirements. The Toolbox incorporated the lessons learned from the past nine years of CubeSats' successes and Analytical Graphics, Inc. (AGI)'s Satellite Tool Kit (STK). The CubeSat Mission Planning Toolbox (CMPT) provides graphical representations of the important requirements a systems engineer needs to plan their mission. This includes requirements for data storage, ground station facilities, orbital parameters, and power. CMPT also allows for a comparison of broadcast (BC) downlinking to Ground Station Initiated (GSI) downlinking for payload data using federated ground station networks. Ultimately, this tool saves time and money for the CubeSat systems engineer

Ce travail porte sur l’étude des mécanismes de phosphorylation des protéines par les sérine/thréonine kinases chez Staphylococcus aureus. Nous avons, tout d’abord, mis en évidence et caractérisé une seconde Ser/Thr-kinase, nommée Stk2. Cette kinase présente peu d’homologies avec les autres Ser/Thr-kinases bactériennes décrites à ce jour, en particulier avec la première Ser/Thr-kinase mise en évidence précédemment chez S. aureus, Stk1. Nous avons ensuite caractérisé dix sites d’autophosphorylation de Stk2 et nous avons montré que trois sites sont nécessaires à son activité. Enfin, nous avons montré que le régulateur global de virulence, SarA, est phosphorylé à la fois par Stk1 et Stk2. La phosphorylation de SarA influence sa capacité de liaison à l’ADN. Cette étude contribue à mieux appréhender, au niveau moléculaire, le rôle des Ser/Thr-kinases dans le métabolisme des bactéries et, plus particulièrement, dans la régulation de leur virulence<br>We report that protein phosphorylation on serine and threonine is required for controlling staphylococcal virulence. We identified and characterized a second serine/threonine kinase, Stk2, in S. aureus. Biochemical analyses revealed that this enzyme displays autokinase activity on both threonine and serine residues. Stk2 is atypical in the sense that it exhibits a weak similarity with the first Ser/Thr-kinase previously detected, Stk1, and its undergoes a different mechanism of activation compared to the other bacterial Ser/Thr-kinases described so far. We also showed that SarA, a major transcription factor that regulates more than a hundred virulence genes, is phosphorylated by both Stk1 and Stk2. Phosphorylation of SarA leads to strong effects on its ability to bind DNA. The study of Stk1 and Stk2, at the molecular level, provides a better understanding of the role of these staphylococcal Ser/Thr-kinases in bacterial metabolism and, in particular, in the regulation of virulence