The generation of hot electrons characterizing the two-plasmon decay (TPD) instability is investigated experimentally both in and out of the plane of polarization of a CO₂ laser incident on an underdense gas target. The results presented here show that, for high intensities (I > ~ 3.5 x 10¹³ W/cm² for a helium target, 1 > ~ 5.5 x 10¹³ W/cm² for a nitrogen target), the electron plasma waves (EPW's) generated by the TPD instability are modified by the electron decay instability (EDI). The relatively short scale lengths at the onset of TPD for these high intensities (<~0.125mm) cause the EPW's propagating towards the higher density regions of the plasma to undergo the EDI resulting in EPW's which contain a vector component perpendicular to the plane of polarization and accelerate electrons by nonlinear Landau damping up to 55° outside the plane of polarization. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Bakgrund: Våld mot vårdpersonal inom psykiatrin är vanligt förekommande. I dagens lagstiftning finns ett krav på att arbetsgivarna ska utreda och åtgärda risker för hot och våld på arbetsplatsen genom kartläggning, information och utbildning. De-eskaleringsteknikerna är viktiga instrument som utgångspunkt i hanteringen för att öka förutsättningarna för stabilitet i situationen. Syfte: Syftet är att beskriva hur de-eskaleringstekniker fungerar i praktiken för att reducera aggressivitet och våld i psykiatriska slutenvårdsmiljöer. Metod: Litterturstudie innefattande elva kvalitativa artiklar. Resultat: De återkommande uttrycken i studierna har identifierats och sammanställts i nio generiska kategorier: vara på plats, läsa patienten och situationen, självkännedom/trygghet, skapa kontakt, lugnt kroppsspråk, lyssna med genuint intresse, tala på ett lugnt, känsligt och korrekt sätt, stärka patienten (empowerment) samt balans mellan empati och kontroll. Kategorierna har inordnats under tre huvudkategorier: individuella egenskaper, handlingar samt effekt - de-eskaleringen syftar till att stärka patienten i ett eget val om stabilisering. Diskussion: Det har påvisats konkreta resultat i användandet av de-eskaleringstekniker men även att de-eskalering är mycket situationsbundet och kräver en adekvat kompetens hos vårdpersonalen.

The need to increase vehicle performance, particularly fuel efficiency, has led to an increased interest in using lightweight metals for vehicle structural components. Lightweight aluminum alloys offer the potential to significantly reduce vehicle mass when structural components that use steel are replaced. Mass reduction is a very efficient route to increase vehicle performance. In vehicles with traditional powertrains, mass reduction can increase fuel efficiency. In vehicles with electrical powertrains, mass reduction can increase driving range. Regardless of the specific structural application, the best performance of any aluminum alloy is only obtained by achieving a microstructure that produces the best material properties. For wrought aluminum alloys, hot and cold deformation steps are critical to obtaining a desirable microstructure prior to the forming of a final component. For sheet material, the first step in controlling the final microstructure is microstructure evolution during hot rolling the cast ingot material. Hot rolling precedes cold rolling of the sheet to final thickness in most commercial sheet manufacturing operations. Microstructure during hot rolling is difficult to study because it requires a combination of high temperatures, fast strain rates and large strains to do so. Furthermore, specimens for microstructural examination must be extracted from these conditions while retaining the characteristics of the specific conditions that are to be studied. Hot torsion testing is the traditional approach to meeting these experimental requirements. In this investigation, a new hot torsion testing instrument is designed, fabricated and validated to enable future experiments that will elucidate microstructure evolution under conditions pertinent to hot rolling. This new instrument is integrated with computerized control and data acquisition systems. Validation experiments were conducted to characterize its capabilities. It is concluded that the completed instrument meets the requirements necessary to study plastic deformation and microstructure evolution in aluminum alloys under conditions relevant to hot rolling. / text

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