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För att åstadkomma en hållbar utveckling lyfts utbildning, av internationella policydokument för en hållbar utveckling, fram som mänsklighetens bästa hopp och mest effektiva medel[1]. Därför intresserar denna studie sig för hur svensk skola tar ansvar för att den potential som utbildning bär på skall utnyttjas. Studieobjektet i denna studie är läroböcker för den inledande fysikkursen på svenska gymnasieskolan, fysik A eller fysik 1. Vidare har undersökningen, med stöd i forskning om undervisning för hållbar utveckling, avgränsats ytterligare genom att endast rikta sig mot de uppgifter som finns i böckerna. Metoden som använts är en kvantitativ innehållsanalys där frågor om någon, och i så fall vilka, aspekter av hållbar utveckling och vilka kunskapsemfaser som betonas har ställts till böckernas samtliga uppgifter. I analysen av studiens resultat framgår det att fysikböcker, genom att ofta ta upp ämnen med anknytning till hållbar utveckling utan att leda den lärande in i resonemang kring hållbar utveckling, inte tar vara på den potential som fysikämnet har när det gäller undervisning för hållbar utveckling. Enligt samma resultat beror undervisningens fokus på hållbar utbildning väldigt mycket på lärarens kunskaper och engagemang. [1]UNESCO, Education for Sustainability from Rio to Johannesburg: Lessons learnt from a decade of commitment. Paris: The International Work Programme on Education, Public Awareness and Sustainability of the United Nations Commission on Sustainable Development, 2002, s. 8

<p>Measuring the dynamics of a quantum bit (qubit) relies on the accurate detection of the quantum state of the system. A widely used method to measure the state of a solid state Josephson junction qubit is to measure the switching current of a Josephson device.</p><p>This work investigates the measurement of the switching current of SQUID samples by means of fast current pulses. The response of a SQUID to a square current pulse has to be measured at the top of a dilution refrigerator through long cables, resulting in bandwidth limitations. A switch in the last instance of a pulse will not be detected, resulting in uncertainties in the detection. We explain how a square bias pulse that is directly followed by a hold level of lower amplitude can be used to circumvent the bandwidth limitations by latching the state of the system it was in after the bias pulse. This corresponds to a sample and hold measurement.</p><p>Every single measurement in a quantum mechanical probability measurement has to be statistically independent. We show correlation measurements for di erent settings of the pulse parameters and at di erent magnitudes of the switching current. A gure of merit for a quantum detector is its resolution. The measurements show that with the sample and hold technique good current resolutions can be obtained, even at very small magnitudes and short pulse durations. In order to make a fast measurement of the switching current, the switching process must occur during the bias pulse. We show in both measurements and computer simulations that a fast switch pulse can induce switching by the hold level,even when the hold level was initially adjusted to a value where it never switched the sample. The computer simulations show that by choosing the hold amplitude low enough, switching occurs rapidly, determined by the bias pulse alone.</p>

<p>The recent decades of research in molecular biology have resulted in break-throughs concerning our knowledge of the genetic code, protein structures and functions of the different cellular components. With this new information follows an increased interest in constructing computational models of the biological systems. A computational model can range from a description of one specific protein to a complete cell or organism. The aim of a computational model is often to complement the experimental studies and help identify essential mechanisms of a system.</p><p>All processes taking place in our cells, from general metabolic processes to cell specific actions, originates from information encoded in our DNA. The first step in transferring the genetic information to a functional protein or RNA, is through the transcription of a gene. The transcription process is controlled by cellular proteins binding to DNA regions called promoters. The term "genetic switch", used in the title of this thesis, refers to a specific change in transcription activity, where one or several promoters get activated or silenced.</p><p>In this thesis, I present studies of the regulation mechanisms in two different genetic switches. The first is a switch between two central promoters in the Epstein- Barr virus. This human virus is mostly known for causing the ’kissing disease’, but is also coupled to several cancer types. Infected cells can change between a resting and a proliferating phenotype, depending on which viral promoter is active. In order to understand what causes uncontrolled proliferation in tumors, it is important to understand the regulation of these viral promoters. The other switch is present in the phage λ, a bacterial virus. This virus has one specific promoter region, controlling expression of two proteins that determine if the phage will remain silent (lysogenic) in the host cell, or start producing new viral particles (go lytic). For the Epstein- Barr virus we tested, and confirmed, the hypothesis that the regulation of the two central promoters can be obtained by only one viral and one human protein. Further, we studied the cooperative effects on one of the promoters, showing that steric hindrance at the promoter region results in a more effective switching than with only cooperative binding present. For the bacteriophage λ we studied the genetically altered λ- Lac mutants, presented by Little & Atsumi in 2006. We demonstrate that the experimental results cannot, in terms of its equilibria, be explained by the mechanisms generally believed to be in control of the lysogenic/ lytic switch.</p>

<p>This thesis reviews the theory of group extensions, gerbes and twisted K-theory. Application to anomalies in gauge theory is briefly discussed. The main results are presented in two appended scientific papers. In the first paper we establish, by construction, a criterion for when an infinite dimensional abelian Lie algebra extension corresponds to a Lie group extension. In the second paper we introduce the fractional loop group L_qG, construct highest weight modules for the Lie algebra and discuss an application to twisted K-theory on G.</p>

<p>Over the last few years, the available computing power allows us to have a deeper insight into photonics components than we ever had before. In this thesis we use the finite element method (FEM) to explore the behavior of the waves in 2D planar microcavities. We demonstrate the tunability of the cavity over a wide range of frequencies taking into account both the thermo-mechanical and the thermo-optical effect. Geometry and material choices are done so that the latter is predominant. We also demonstrate an odd mode disappearing phenomenon reported here for the first time as far as we know. Using this knowledge, we design two structures with these remarkable properties.</p><p>One of the devices will be used as micro-sized solid-state dye laser with Rhodamine 6G as the active medium and SU-8 polymer as a cavity material in sizes that have never been reached before. This opens new opportunities not only for future implementation for “labs-on-a-chip” (LOC) but also for a higher integration density of optical communication systems. The second device is a wavefront shaper creating plane waves from a point source performing the functions of beam shaper and beam splitter with plane wave as the output result.</p><p>After an introduction to FEM and comparison with a rival algorithm, some issues related to FEM in electromagnetic simulation are resolved and explained. Finally, some fabrication techniques with feature sizes <100 nm, such as electron beam lithography (EBL) and nano-imprint lithography (NIL), are described and compared with other lithographic techniques.</p>

No description available.

Diss. (sammanfattning) Uppsala : Univ., 2009. / Härtill 5 uppsatser.

This thesis contains the results of research in the fields of spectral control, efficiency andlifetime of high-power, rare-earth doped fiber lasers, properties which are of greatimportance for scientific and industrial applications. Volume Bragg gratings (VBGs) has forthe first time been used together with fiber lasers and the laser performance in terms ofspectral purity, thermal stability, and tunability was evaluated. It was found that VBGs arean excellent high-contrast spectral filter for many fiber laser designs where bulk optics arenecessary, or for speciality fibers such as photonic crystal fibers or large-mode area fibers. Itis also shown that they work equally well in low power and very high-power configurations,i.e. for fiber lasers ranging three orders of magnitude in output power, from ~100 mW to &gt;100 W. Furthermore, VBGs are shown to work very well as tunable spectral filters,producing a narrow emission linewidth in a compact setup. Concerning efficiency, it was shown how cryogenic cooling of the fiber gain-mediasubstantially increased the efficiency. The reasons are an increased pump absorption, anincreased gain cross-section, and a decreased threshold. The broad spectral output resultingfrom the low temperatures is shown to be easily mitigated by implementing a VBG as oneof the cavity mirrors. The low operating temperature is also shown to efficiently suppressself-pulsing in the fiber laser, which, if left unchecked, can lead to catastrophic break-downof the fiber end-faces. The increased absorption and suppressed self-pulsing allowed a fiberlength long enough to almost completely absorb the pump, which meant that, for the samepump power, more than 60 % higher output-power was attained. Finally, the lifetime issue of Yb-doped fiber lasers was addressed. It was found that Cecodopingsubstantially reduced the photodarkening-rate while leaving other fiber parametersessentially unchanged. This is especially important for Yb-doped fiber lasers emitting at 980nm, as the high inversion required make them very susceptible to photodarkening. It wasshown that the output power in Yb-doped fiber lasers degraded quickly when no Cecodopingwas present and, conversely, with the right Yb/Ce-codoping ratio, degradationfreelasing could be achieved for many hours. The research results obtained in this work could be of great interest to scientists andengineers working with spectroscopy, display systems, non-linear optics to just name a fewexamples. / QC 20100721

Det stora temat för den här undersökningen är att förstå hur elever i grundskolans senare del uppfattar fysikundervisningen med avseende på svårighetsgrad. I tillägg till detta undersöks elevernas intresse för fysikämnet samt ytterligare några faktorer vilka kan förklara uppfattningen om detta ämne.   Undersökningen består av en enkätundersökning där elever fått ange till vilken grad de håller med om olika påståenden. Slutsatsen av svaren är att det är stor spridning i åsikt om hur svårt fysikämnet är. Detsamma gäller för frågan om hur intresserade eleverna är för ämnet. Slutsatsen är att det inte enkelt går att säga om fysikämnet upplevs svårt eller inte, då spridningen är för stor. Däremot visar undersökningen och analysen att en väsentlig del av eleverna inte tycker att fysik är svårt och att likaså en väsentlig del tycker att det är svårt. Därtill finns det många elever som till viss del håller med om att just fysik är svårt. Däri ligger också en av de stora utmaningarna som lärare. Hur samtidigt tillfredställa dem som tycker att det inte är svårt samtidigt som de som tycker det är svårt också ska bli tillfredsställda?   I tillägg till detta har en regressionsanalys gjorts utifrån svaren i enkätundersökningen. Den kopplar ihop förklaringar till vad som påverkar att elever tycker ämnet är svårt eller intressant. En stark koppling återfinns just mellan intresse och uppfattning om svårighetsgrad. Ju större intresse för ämnet, desto mindre svårt uppfattas det.