• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 4
  • 2
  • 1
  • Tagged with
  • 17
  • 6
  • 5
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

”Hela Sveriges dilemma” : SFI:s roll och insatser för etablering av nyanlända

Andersson, Sebastian January 2016 (has links)
Denna studie syftar att undersöka olika insatser för etablering som kan erbjudas nyanlända i samband med SFI-studier samt vilken roll studie- och yrkesvägledarna spelar i processen. Detta görs genom semistrukturerade intervjuer med tre studie- och yrkesvägledare verksamma vid SFI- verksamheter i en specifik kommun där yrkessvenska erbjuds att läsas i form av så kallade Sfx- utbildningar. Resultaten visar att svenskundervisning i kombination med en viss yrkesbakgrund verkar agera stimulerande för såväl genomströmningen i utbildningen såsom möjligheten till etablering inom relevant utbildning/arbetsmarknad. Studie- och yrkesvägledarna spelar en viktig roll i nätverkande med den relevanta bransch- och fackverksamheten vilket ger målgruppen möjlighet till lärande på arbetsplatser och mentorskap. För de SFI-elever som faller utanför ramen för Sfx-utbildning finns istället på vissa skolor yrkesförberedande SFI och möjligheter att själva skaffa etableringsfördelar genom bland annat mentorsprogram. I sitt uppdrag anser sig studie- och yrkesvägledarna arbeta mer som dörröppnare än grindvakter. Potentiella utvecklingsområden inför framtiden anser man vara en vidareutveckling av utbildningar med yrkessvenska inom ramen av de nya lagförändringar som möjliggör kombinationer av SFI och gymnasiekurser men framförallt lyfts samverkan med Arbetsförmedlingen som ett område som behöver utvecklas. I dagsläget pekar man även ut resursbrister i verksamheterna som ett hinder för att erbjuda aktiv vägledning till eleverna.
2

Methods and Instrumentation of Sample Injection for XFEL Experiments

January 2014 (has links)
abstract: ABSTRACT X-Ray crystallography and NMR are two major ways of achieving atomic resolution of structure determination for macro biomolecules such as proteins. Recently, new developments of hard X-ray pulsed free electron laser XFEL opened up new possibilities to break the dilemma of radiation dose and spatial resolution in diffraction imaging by outrunning radiation damage with ultra high brightness femtosecond X-ray pulses, which is so short in time that the pulse terminates before atomic motion starts. A variety of experimental techniques for structure determination of macro biomolecules is now available including imaging of protein nanocrystals, single particles such as viruses, pump-probe experiments for time-resolved nanocrystallography, and snapshot wide- angle x-ray scattering (WAXS) from molecules in solution. However, due to the nature of the "diffract-then-destroy" process, each protein crystal would be destroyed once probed. Hence a new sample delivery system is required to replenish the target crystal at a high rate. In this dissertation, the sample delivery systems for the application of XFELs to biomolecular imaging will be discussed and the severe challenges related to the delivering of macroscopic protein crystal in a stable controllable way with minimum waste of sample and maximum hit rate will be tackled with several different development of injector designs and approaches. New developments of the sample delivery system such as liquid mixing jet also opens up new experimental methods which gives opportunities to study of the chemical dynamics in biomolecules in a molecular structural level. The design and characterization of the system will be discussed along with future possible developments and applications. Finally, LCP injector will be discussed which is critical for the success in various applications. / Dissertation/Thesis / Doctoral Dissertation Physics 2014
3

Time-Resolved Crystallography using X-ray Free-Electron Laser

January 2015 (has links)
abstract: Photosystem II (PSII) is a large protein-cofactor complex. The first step in photosynthesis involves the harvesting of light energy from the sun by the antenna (made of pigments) of the PSII trans-membrane complex. The harvested excitation energy is transferred from the antenna complex to the reaction center of the PSII, which leads to a light-driven charge separation event, from water to plastoquinone. This phenomenal process has been producing the oxygen that maintains the oxygenic environment of our planet for the past 2.5 billion years. The oxygen molecule formation involves the light-driven extraction of 4 electrons and protons from two water molecules through a multistep reaction, in which the Oxygen Evolving Center (OEC) of PSII cycles through 5 different oxidation states, S0 to S4. Unraveling the water-splitting mechanism remains as a grant challenge in the field of photosynthesis research. This requires the development of an entirely new capability, the ability to produce molecular movies. This dissertation advances a novel technique, Serial Femtosecond X-ray crystallography (SFX), into a new realm whereby such time-resolved molecular movies may be attained. The ultimate goal is to make a “molecular movie” that reveals the dynamics of the water splitting mechanism using time-resolved SFX (TRSFX) experiments and the uniquely enabling features of X-ray Free-Electron Laser (XFEL) for the study of biological processes. This thesis presents the development of SFX techniques, including development of new methods to analyze millions of diffraction patterns (~100 terabytes of data per XFEL experiment) with the goal of solving the X-ray structures in different transition states. ii The research comprises significant advancements to XFEL software packages (e.g., Cheetah and CrystFEL). Initially these programs could evaluate only 8-10% of all the data acquired successfully. This research demonstrates that with manual optimizations, the evaluation success rate was enhanced to 40-50%. These improvements have enabled TR-SFX, for the first time, to examine the double excited state (S3) of PSII at 5.5-Å. This breakthrough demonstrated the first indication of conformational changes between the ground (S1) and the double-excited (S3) states, a result fully consistent with theoretical predictions. The power of the TR-SFX technique was further demonstrated with proof-of principle experiments on Photoactive Yellow Protein (PYP) micro-crystals that high temporal (10-ns) and spatial (1.5-Å) resolution structures could be achieved. In summary, this dissertation research heralds the development of the TR-SFX technique, protocols, and associated data analysis methods that will usher into practice a new era in structural biology for the recording of ‘molecular movies’ of any biomolecular process. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2015
4

Life In Motion: Visualizing Biomacromolecules By Time-Resolved Serial Femtosecond Crystallography

January 2018 (has links)
abstract: Time-resolved serial femtosecond crystallography is an emerging method that allows for structural discovery to be performed on biomacromolecules during their dynamic trajectory through a reaction pathway after activation. This is performed by triggering a reaction on an ensemble of molecules in nano- or microcrystals and then using femtosecond X-ray laser pulses produced by an X-ray free electron laser to collect near-instantaneous data on the crystal. A full data set can be collected by merging a sufficient number of these patterns together and multiple data sets can be collected at different points along the reaction pathway by manipulating the delay time between reaction initiation and the probing X-rays. In this way, these ‘snapshot’ structures can be viewed in series to make a molecular movie, allowing for atomic visualization of a molecule in action and, thereby, a structural basis for the mechanism and function of a given biomacromolecule. This dissertation presents results towards this end, including the successful implementations of the first diffusive mixing chemoactivated reactions and ultrafast dynamics in the femtosecond regime. The primary focus is on photosynthetic membrane proteins and enzymatic drug targets, in pursuit of strategies for sustainable energy and medical advancement by gaining understanding of the structure-function relationships evolved in nature. In particular, photosystem I, photosystem II, the complex of photosystem I and ferredoxin, and 3-deoxy-D-manno-2-octulosonate-8-phosphate synthase are reported on, from purification and isolation, to crystallogenesis, to experimental design and data collection and subsequent interpretation of results and novel insights gained. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2018
5

Acoustic Focusing of Lysozyme Crystals / Akustisk fokusering av lysozymkristaller

Junestrand, Måns January 2023 (has links)
Acoustic focusing of microscale protein crystals with acoustophoresis technology could reduce clogs during experiments with the scientific technique serial femtosecond x-ray crystallography (SFX). SFX determines molecular structures of proteins, these structures are valuable in drug discovery and fundamental biomedical research. Lysozyme crystals were focused in their own mother liquor and dilutions with PBS buffer. The aim of these tests were to study how the acoustic contrast factor Φ changes with the medium. Recorded experiments were analyzed using the particle tracking software Trackmate to extract velocities and radii. The lysozyme crystals changed morphologies in large dilutions of PBS buffert, they either became rounder or broke into fragments. The changed forms are likely caused by dissolution behaviors; some dilutions were unstable, but not unstable enough to dissolve the crystals completely.  Measured velocities during focusing of the crystals had large variance. Sinusoidal fits of the velocities had significant increases in amplitudes for larger dilutions of PBS. A change in acoustic contrast factor Φ could be the cause for the increased amplitudes, but the results do not rule out other causes. There are currently major knowledge gaps about using protein crystals as particles with acoustophoresis technologies, hence many ideas for future works have been proposed in this master thesis report. / Akustisk fokusering av mikrometers-stora proteinkristaller med hjälp av ultraljudsteknik skulle kunna reducera proppar under experiment med tekniken seriell femtosekundskristallografi (SFX). SFX kan avgöra vilken struktur proteinmolekyler har, dessa strukturer är värdefulla för industriell utveckling av nya läkemedel och fundamental biomedicinsk forskning. Proteinkristaller av lysozym har fokuserats i sin egen kristalliseringslösning och utspädningar av PBS. Målet med de här experimenten var att se om den akustiska flödeskontrasten Φ kunde bli påverkad. Fokuseringar spelades in och partiklarnas hastigheter vid fokuseringarna mättes med hjälp av Trackmate (en mjukvara för partikelspårning). I de större utspädningarna förändrades lysozymkristallernas former, de blev antingen mer runda eller så blev de små bitar. Förändringen skedde förmodligen på grund av upplösningsmekanismer i instabila utspädningar.  Uppmätta hastigheter vid testerna hade stor varians, men kurvanpassningar av data tyder på att hastigheterna ökar signifikant med utspädningar av PBS. Den akustiska flödeskontrasten Φ kan vara orsaken för ökade hastigheter, men andra hypoteser gick inte att utesluta med resultaten. Stora kunskapshål finns om akustisk fokusering av proteinkristaller, därför har många idéer för framtida experiment och arbeten föreslagits i rapporten.
6

Från grundskola till gymnasium på ett år : Yrkessvenska för invandrade akademiker

Schönning, Anna, Lindgren, Shorok January 2010 (has links)
<p>Många invandrare i Sverige har en akademisk utbildning från sitt hemland. För att tillvarata invandrarakademikers kompetenser har yrkessvenska för invandrare så kallade Sfx- utbildningar startats. Syftet med studien är att belysa hur akademiker med invandrarbakgrund upplever betydelsen av Sfx- utbildningarna för sina möjligheter till etablering på den svenska arbetsmarknaden. En kvalitativ metod har använts och sex intervjuer har genomförts. Deltagarna har visat sitt missnöje med svenskundervisningen inom den reguljära Sfi- skolan. Det framkommer även att yrkessvenskan som Sfx erbjuder är eftertraktat. Att de studerar svenska intensivt samt att de har en gemensam yrkesbakgrund gör att de känner sig motiverade till att lära sig svenska språket. Utifrån deltagarnas humankapital finner vi flera förklaringar till varför de har svårt att få arbete. Det handlar om bristande kunskaper i svenska språket, om bristande kunskaper om samhället men framförallt bristande kunskaper om regler på arbetsmarknaden och i samhället.</p>
7

Från grundskola till gymnasium på ett år : Yrkessvenska för invandrade akademiker

Schönning, Anna, Lindgren, Shorok January 2010 (has links)
Många invandrare i Sverige har en akademisk utbildning från sitt hemland. För att tillvarata invandrarakademikers kompetenser har yrkessvenska för invandrare så kallade Sfx- utbildningar startats. Syftet med studien är att belysa hur akademiker med invandrarbakgrund upplever betydelsen av Sfx- utbildningarna för sina möjligheter till etablering på den svenska arbetsmarknaden. En kvalitativ metod har använts och sex intervjuer har genomförts. Deltagarna har visat sitt missnöje med svenskundervisningen inom den reguljära Sfi- skolan. Det framkommer även att yrkessvenskan som Sfx erbjuder är eftertraktat. Att de studerar svenska intensivt samt att de har en gemensam yrkesbakgrund gör att de känner sig motiverade till att lära sig svenska språket. Utifrån deltagarnas humankapital finner vi flera förklaringar till varför de har svårt att få arbete. Det handlar om bristande kunskaper i svenska språket, om bristande kunskaper om samhället men framförallt bristande kunskaper om regler på arbetsmarknaden och i samhället.
8

Lietuvos akademinių bibliotekų tinklas: Lietuvos magistrantūros studentų baigiamųjų darbų, daktaro disertacijų ir jų santraukų elektroninių dokumentų informacijos sistema / Lithuanian Academic Library Network: Information system of Digital Library of Theses and Dissertation

Franckevičius, Arūnas 12 July 2005 (has links)
Storage, preservation and access of Master's and PhD theses as well as their abstracts in an electronic form provide unique opportunities to the academic community in Lithuania as well as worldwide. The main aims of this project were to establish an archive (Lithuanian ETD IS) of Lithuanian student final year projects, PhD theses and their abstracts in an electronic form (ETD). This archive should become a part of the Lithuanian academic library network (LABT), ensuring registration and storage of ETD documents, and should be accessible by the academic community in Lithuania and the rest of the world. In order to develop the Lithuanian ETD IS, the most widely used formats and methods for access, retrieval and exchange with NDLTD and other national ETD projects were employed. A solution, ensuring efficient ETD registration, preservation, retrieval and access by users, is presented and discussed. Application of the ExLibris programming products (ALEPH500™, MetaLib™, SFX™), developed during the LABT project, was used.
9

The Importance of Radiation Damage for Molecular Reconstruction from FEL Diffraction Experiments

Bjärnhall Prytz, Nicklas January 2018 (has links)
Serial Femtosecond X-ray crystallography (SFX) is a rapidly growing experimental technique by which the structure of a crystalline sample may be determined. The X- rays arrive at the sample in pulse trains of the order of femtoseconds. Each X-ray pulse train hits a unique crystal at a random orientation and produces a diffraction pattern on the detector and series of patterns is obtained, which is the reason for the denomination "serial". Here, the radiation damage done to a sample during an SFX experiment was studied by simulating diffraction patterns including damage. Throughout, a model reference structure in the form of a reflection list was used to simulate patterns. The aim was to minimise the effects of damage through a correction based on available damage data. Firstly, a simulation case with made-up damage data was performed. The made-up data was used to modify the structure factors such that they would appear damaged. After structural reconstruction, the same data was used to correct for the damage. This was done as a validation of the method pipeline. Secondly, a more realistic case, with actual simulated damage data and a distribution of incident intensities was carried out. The expectation value of the distribution was used to correct for damage. It is found for both cases that the damage correction improves the agreement between simulated data and the original model. This is a first step toward successfully correcting for radiation damage which would be a big step forward for SFX.
10

What is the optimum delay between visual and auditory stimuli that is perceived as synchronous for video game SFX? : A methodology for testing synchronization of audiovisual stimuli in video games.

Lyth Waters, Malcolm January 2022 (has links)
Synchronization of visual and auditory stimuli is important for creating a convincing sound designin games. Understanding the factors that constitute synchrony is both a question of synchrony inthe physical space but also an experience based on perception. Developing on a simpleflash-and-click test used by Eijk (2008), a test was designed to determine the point of synchrony in agame engine environment, a system that inherently has latencies. Test subjects were tasked withfinding a point of subjective synchrony (PSS), meaning the point where they perceived auditoryand visual stimuli to be synchronized. The visual stimulus was a commonly occurring rifle modeland three sound designs with different characteristics were implemented into the Unreal 4 Engine.The latencies of the system were calculated and summed with the PSS value of van Eijk’s (2008)flash-and-click test to create a hypothesized PSS. The results showed that the PSS for the testsubject group aligned with the PSS values given by van Eijk (2008) and that this test has potentialfor testing synchrony in game engine environments.

Page generated in 0.0435 seconds