156 research outputs found
Interplanetary field and plasma during initial phase of geomagnetic storms
Twenty-three geomagnetic storm events during 1966 to 1970 were studied by using simultaneous interplanetary magnetic field and plasma parameters. Explorer 33 and 35 field and plasma data were analyzed on large-scale (hourly) and small-scale (3 min.) during the time interval coincident with the initial phase of the geomagnetic storms. The solar-ecliptic Bz component turns southward at the end of the initial phase, thus triggering the main phase decrease in Dst geomagnetic field. The By component also shows large fluctuations along with Bz. When there are no clear changes in the Bz component, the By shows abrupt changes at the main phase onset. On the small-scale, behavior of the magnetic field and electric field were studied in detail for the three events; it is found that the field fluctuations in By, Bz and Ey and Ez are present in the initial phase. In the large-scale, the behavior field remains quiet because the small-scale variations are averaged out. It appears that large as well as small time scale fluctuations in the interplanetary field and plasma help to alter the internal electromagnetic state of the magnetosphere so that a ring current could causing a geomagnetic storm decrease
Computer networks for remote laboratories in physics and engineering
This paper addresses a relatively new approach to scientific research, telescience, which is the conduct of scientific operations in locations remote from the site of central experimental activity. A testbed based on the concepts of telescience is being developed to ultimately enable scientific researchers on earth to conduct experiments onboard the Space Station. This system along with background materials are discussed
Data distribution satellite
A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs
Technology Advances for Space Shuttle Processing
The Space Systems Integration and Operations Research Applications (SIORA) Program was initiated in late 1986 as a cooperative applications research effort between Stanford University, NASA Kennedy Space Center (KSC), and Lockheed Space Operations Company (LSOC). One of the major initial SIORA tasks was the application of automation and robotics technology to all aspects of the Shuttle tile processing and inspection system. This effort has adopted a systems engineering approach consisting of an integrated set of rapid prototyping testbeds in which a government/university/industry team of users, technologists, and engineers test and evaluate new concepts and technologies within the operational world of Shuttle. These integrated testbeds include speech recognition and synthesis, LASER imaging systems, distributed Ada programming environments, distributed relational database architectures, distributed computer network architectures, multi-media workbenches, and human factors considerations
Paper Session II-C - Introducing New Technologies Into Space Station Subsystems
In a cooperative effort between Kennedy Space Center, Stanford University and Lockheed Space Operations Company, a new systems engineering methodology has been developed and applied in the operational world of Shuttle processing. The new engineering approach stresses the importance of identifying, quantitatively assessing, and managing system performance and risk related to the dynamic nature of requirements, technology, and operational concepts. Under the cooperative program entitled, Space Systems Integration and Operations Research Applications (SIORA), the modernization of the processing operations for the Shuttle thermal protection system (IPS) or tiles became the first application of the engineering methodology. This effort adopted an approach consisting of an integrated set of rapid prototyping testbeds in which a government/ university/industry team of users, technologists, and engineers tested and evaluated new concepts and technologies within and in parallel to Shuttle processing operations. The integrated set of technologies introduced included speech recognition and synthesis capabilities, laser imaging inspection systems, distributed Ada programming environments, distributed relational database architectures, in addition to distributed computer network architectures, multi-media workbenches, expert system applications, probabilistic risk assessment modeling, and human factors considerations. The successful operational implementation of the integrated prototype, referred to as the Space Shuttle Tile Automation System, has validated the engineering methodology and strongly indicates that the same approach would be a viable systems engineering and project management tool for Freedom Space Station. This paper will address the lessons learned from the Shuttle processing experience and will present concepts which are applicable to the design and development of the Freedom Space Station
California Space Grant Consortium
The organizational and administrative structure of the CaSGC has the Consortium Headquarters Office (Principal Investigator - Dr. John Kosmatka, California Statewide Director - Dr. Michael Wiskerchen) at UC San Diego. Each affiliate member institution has a campus director and an scholarship/fellowship selection committee. Each affiliate campus director also serves on the CaSGC Advisory Council and coordinates CMIS data collection and submission. The CaSGC strives to maintain a balance between expanded affiliate membership and continued high quality in targeted program areas of aerospace research, education, workforce development, and public outreach. Associate members are encouraged to participate on a project-by-project basis that meets the needs of California and the goals and objectives of the CaSGC. Associate members have responsibilities relating only to the CaSGC projects they are directly engaged in. Each year, as part of the CaSGC Improvement Plan, the CaSGC Advisory Council evaluates the performance of the affiliate and associate membership in terms of contributions to the CaSGC Strategic Plan, These CaSGC membership evaluations provide a constructive means for elevating productive members and removing non-performing members. This Program Improvement and Results (PIR) report will document CaSGC program improvement results and impacts that directly respond to the specific needs of California in the area of aerospace-related education and human capital development and the Congressional mandate to "increase the understanding, assessment, development and utilization of space resources by promoting a strong education base, responsive research and training activities, and broad and prompt dissemination of knowledge and technology"
Lærerstuderendes arbejde med didaktisk modellering
Med afsæt i begreberne pædagogisk øvelse og didaktisk modellering analyseres en case, hvor lærerstuderende i campusundervisningen har arbejdet med at konstruere didaktiske planlægningsmodeller. Undersøgelsen har praksisteoretisk reference både i forskningstilgang og som epistemologisk forståelse af professionelles læring. Metodisk er det et casestudie med gruppeinterview analyseret gennem refleksiv tematisk analyse. Analysen viser, at 1) det giver både udfordringer og muligheder at blive kastet ud i modelleringsopgaven, 2) de lærerstuderende bringer deres første praktikobservationer fra skolens arena i spil, 3) de oplever, at dette er en anderledes tilgang, som kaldes mere kreativ, og 4) opgaven bidrager til en begyndende didaktisk modelleringstænkning. Øvelsen med didaktisk modellering fungerer således som en generator for didaktisk refleksion. Kvalitet fremstår gennem de lærerstuderendes dedikation til opgaven som professionelle, og deres demonstration af didaktisk forståelse, hvor de argumenterer for egne modeller og diskuterer andres fx med reference til elevernes lyst til læring og fordybelse
The G140S mutation in HIV integrases from raltegravir-resistant patients rescues catalytic defect due to the resistance Q148H mutation
Raltegravir (MK-0518) is the first integrase (IN) inhibitor to be approved by the US FDA and is currently used in clinical treatment of viruses resistant to other antiretroviral compounds. Virological failure of Raltegravir treatment is associated with mutations in the IN gene following two main distinct genetic pathways involving either the N155 or Q148 residue. Importantly, in most cases, an additional mutation at the position G140 is associated with the Q148 pathway. Here, we investigated the viral DNA kinetics for mutants identified in Raltegravir-resistant patients. We found that (i) integration is impaired for Q148H when compared with the wild-type, G140S and G140S/Q148H mutants; and (ii) the N155H and G140S mutations confer lower levels of resistance than the Q148H mutation. We also characterized the corresponding recombinant INs properties. Enzymatic performances closely parallel ex vivo studies. The Q148H mutation ‘freezes’ IN into a catalytically inactive state. By contrast, the conformational transition converting the inactive form into an active form is rescued by the G140S/Q148H double mutation. In conclusion, the Q148H mutation is responsible for resistance to Raltegravir whereas the G140S mutation increases viral fitness in the G140S/Q148H context. Altogether, these results account for the predominance of G140S/Q148H mutants in clinical trials using Raltegravir
Efficient transduction of LEDGF/p75 mutant cells by complementary gain-of-function HIV-1 integrase mutant viruses
Controlling the specificity of retroviral DNA integration could improve the safety of gene therapy vectors, and fusions of heterologous chromatin binding modules to the integrase (IN)–binding domain from the lentiviral integration host cofactor lens epithelium–derived growth factor (LEDGF)/p75 are a promising retargeting strategy. We previously proposed the utility of IN mutant lentiviral vectors that are selectively activated by complementary LEDGF/p75 variants, and our initial modifications in human immunodeficiency virus type 1 IN and LEDGF/p75 supported about 13% of wild-type vector transduction activity. Here we describe the selection and characterization of the K42E gain-of-function mutation in IN, which greatly improves the efficiency of this system. Both K42E and initial reverse-charge mutations in IN negatively affected reverse transcription and integration, yet when combined together boosted viral transduction efficiency to ∼75% of the wild-type vector in a manner dependent on a complementary LEDGF/p75 variant. Although the K42E mutation conferred functional gains to IN mutant viral reverse transcription and integration, only the integration boost depended on the engineered LEDGF/p75 mutant. We conclude that the specificity of lentiviral retargeting strategies based on heterologous LEDGF/p75 fusion proteins will benefit from our optimized system that utilizes the unique complementation properties of reverse-charge IN mutant viral and LEDGF/p75 host proteins
Udviklingslaboratorier som metode til kompetenceudvikling i teknologiforståelse: Erfaringer med TEKFAG-modellen
Artiklen beskriver forfatternes egne erfaringer med udviklingslaboratorier som metode til kompetenceudvikling af undervisere på læreruddannelsen i teknologiforståelse som delfaglighed i undervisningsfaget dansk og grundfaget pædagogik og lærerfaglighed (PL). Indledningsvis redegøres for teori om udviklingslaboratorier og teknologiforståelse, hvorefter forfatterne redegør for egne ‘didaktiske refleksioner’ over to af de afholdte udviklingslaboratorier. Afslutningsvis diskuteres sigtelinjer for det gode udviklingslaboratorie i en kompetenceudviklingssammenhæng. Artiklens to refleksioner fremhæver især, hvordan udviklingslaboratoriet kan åbne udviklingsrum i veletablerede fag og fagligheder, hvordan de afhænger af deltagernes kompetencer og motivation til at foretage konkrete eksperimenter og ikke mindst hvordan laboratorier kan fremme fagmøder og meningsskabelse mellem de mange fag og fagområder, der er impliceret i teknologiforståelse i dansk og PL.The article describes the intentions behind the TEKFAG-model for competence development in ‘technology comprehension’ as a new subject area on digital technologies nested within other subject areas such as Danish and Pedagogy and Teachers Professionalism. The model is focused on the competence development of teacher educators and designed to manage the specific challenges associated with a subject area (technology comprehension), that is not only nested within other subject areas, but also in itself under development. The TEKFAG-model is based on a method called ‘development laboratories’ and the article investigates the intentions and characteristics of these laboratories in both theory and practice. It is discussed how development laboratories may help develop sustainable competences in technology comprehension as a new and evolving subject area
- …