An experimental setup for high resolution 10.5 eV laser-based angle-resolved photoelectron spectroscopy using a time-of-flight electron analyzer

We present an experimental setup for laser-based angle-resolved time-of-flight (LARTOF) photoemission. Using a picosecond pulsed laser, photons of energy 10.5 eV are generated through higher harmonic generation in xenon. The high repetition rate of the light source, variable between 0.2-8 MHz, enables high photoelectron count rates and short acquisition times. By using a Time-of-Flight (ToF) analyzer with angle-resolving capabilities electrons emitted from the sample within a circular cone of up to \pm15 degrees can be collected. Hence, simultaneous acquisition of photoemission data for a complete area of the Brillouin zone is possible. The current photon energy enables bulk sensitive measurements, high angular resolution and the resulting covered momentum space is large enough to enclose the entire Brillouin zone in cuprate high-Tc superconductors. Fermi edge measurements on polycrystalline Au shows an energy resolution better than 5 meV. Data from a test measurement of the Au(111) surface state is presented along with measurements of the Fermi surface of the high-Tc superconductor Bi2212.Comment: 9 pages, 7 figure

Hypothermia as an adjunctive therapy in Acute Myocardial Infarction and Cardiogenic Shock

INTRODUCTION: Reperfusion therapy in patients with an ongoing ST-elevation myocardial infarction (STEMI) is to re-establish coronary flow in the epicardial arteries as soon as possible in order to reduce infarct size and associated complications. Hypothermia has in experimental studies been shown to reduce infarct size. Clinical trials, however, have not been able to show this effect, possibly because a therapeutic temperature was not reached before reperfusion in the majority of the patients allocated to hypothermia treatment. We aimed to evaluate if hypothermia initiated before reperfusion would reduce infarct size. Furthermore, a protocol utilising a combination of an infusion of cold saline and endovascular cooling catheter was evaluated. Finally, the effects of hypothermia in cardiogenic shock were investigated. MATERIAL and METHODS: For paper I-III, an experimental closed chest porcine model was used. Ischemia was induced by occlusion of the LAD using a PCI-balloon. Different hypothermia protocols using cold saline, endovascular cooling in combination or alone were tested. Infarct size and microvascular obstruction were evaluated using ex-vivo MRI. In paper III, endovascular cooling alone was investigated in a porcine model of cardiogenic shock. In paper IV, the safety and feasibility of the hypothermia protocol utilised in paper I, II was tested in a clinical trial in patients with STEMI. RESULTS: Paper I: Combination hypothermia (a combination of an infusion of cold saline and endovascular cooling catheter), if initiated before reperfusion reduced infarct size by 39%, and abolished microvascular obstruction compared to normothermia. Furthermore, the hypothermia protocol achieved a reduction in core body temperature to < 35°C in <10 min. However, hypothermia induced at the onset of reperfusion reduced microvascular obstruction by 66%, but did not affect infarct size. In Paper II, combination hypothermia reduced infarct size by 18% and microvascular obstruction was virtually abolished despite prolonged ischemic time compared to normothermia. Furthermore, an infusion of cold saline alone did not reduce infarct size, but reduced microvascular obstruction by 74%. Prolonged post-reperfusion hypothermia did not offer any additional. In Paper III, endovascular hypothermia improved survival (8/8 vs. 3/8, hypothermia vs. control), improved hemodynamic parameters, and reduced acidosis in cardiogenic shock. Paper IV: Combination hypothermia in patients with STEMI was able to safely reach a core body temperature of < 35°C before reperfusion without delaying primary PCI, and resulted in a 38% reduction in infarct size. CONCLUSIONS: In order for hypothermia treatment to reduce infarct size, it needs to be initiated before reperfusion. The results indicate that it is safe and clinically feasible to induce hypothermia by using a combination of cold saline infusion and endovascular cooling prior to reperfusion in awake STEMI patients without delaying time to reperfusion. Furthermore, hypothermia improves outcome in cardiogenic shock. Larger randomized clinical trials are needed to verify these findings and to assess possible long term clinical benefit for the patients

What Gaia can reveal about the matter distribution in the Milky Way

Context. With the goal to accurately map about a billion of the Milky Way stars, the astrometric satellite Gaia was launched in December 2013. Its high precision and sensitivity will lead to better understanding of the Galactic structure and evolution. Also, it will be possible to probe the matter distribution in the Galaxy. Aims. To study how well the Galactic matter distribution can be determined from Gaia data, using a direct application of the Jeans equations. Methods. An expression for mass density applicable to collisionless gravitational systems can be found by combining the second Jeans equations with Poisson’s equation. Through orbit integration of a few million stars in a potential model of the Milky Way, astrometric data were simulated. Taking into account extinction using a smooth model based on hydrogen observations, measurement errors expected from Gaia were generated for the chosen tracer stars (M-giants). Applying a grid covering the region of the model set by the magnitude limits of Gaia, the mass density was estimated in every grid-bin and thus resolution was achieved. Results. I find that within the region limited by 5.5 < R < 12 kpc and |z| < 200 pc, the mass density can be estimated with better than 35 % accuracy. Within the smaller region limited by 6 < R < 9 kpc and |z| < 50 pc, the estimation error has decreased to a few percent and in the Solar neighbourhood it will be possible to probe the matter distribution with about one percent precision. Both the regions mentioned cover a large part of the Perseus spiral arm and spans over different locations where the individual components of the Galaxy are prominent. Conclusions. The extensive regions probed with this method make it possible to determine the large-scale structure of the Milky Way, including e.g., more accurately determined radial and vertical scale lengths. It will be possible to improve the estimation of the local mass density by about a factor ten compared to the current values. The precision of the method allows to test different scenarios for the distribution of dark matter in the disk and elsewhere in the Galaxy

DET SKA VARA SNYGGT OCKSÅ - om att lära sig bygga för personer med synnedsättning

Riksföreningen Aktiva Synskadade har en kursgård i vacker naturmiljö som jag valt att basera examenarbetet på. Syftet är att redovisa ett gestaltningsförslag som använder förutsättningarna för att skapa god hus- och utemiljö för personer med synnedsättning till att skapa god arkitektur för alla. Litteratursökningen tar både upp specifika faktorer såsom orienterbarhet för personer med synnedsättningar, och mer generella teorier om hur vi människor uppfattar och tolkar position och rörelse i det tredimensionella rummet. Föreningsmedlemmar med synnedsättning har intervjuats där de analyserar inomhusmiljön på kursgården och berättar om erfarenheter, prioriteringar och personlig smak kring arkitektur. Ljushetskontraster är en central del av projektet. Här ingår metod för att mäta färgers ljushet, analys av befintliga inomhusmiljöer och egna principförslag på förbättring av befintliga och nya miljöer. Gestaltningsförslaget består även av principförslag för ledstråk, ombyggnad av befintliga hus och en ny verkstadsbyggnad. Min vilja har varit att göra tillgänglig arkitektur genom hela gestaltningsprocessen utan att estetiska värden går förlorade

Ripples on water : a study about understanding change over time of the Leader method from the perspective of the actors in Bohuslän

Sedan inträdet i EU 1995 har Sverige använt en metod, Leader, för att samordna aktiviteter för ekonomisk utveckling på landsbygden. Metoden bygger på ett trepartnerskap mellan privat, ideell och offentlig sektor. Dessa sektorer skall ta ett gemensamt beslut kring en utvecklingsstrategi och välja ut de projekt som går i linje med målsättningen för området. Syftet med studien var att förstå förändring av arbetet med Leader över tid sett utifrån de olika aktörerna som agerar inom ramen för metoden. För att besvara syftet och frågeställningen har en kvalitativ metod använts. Studien är baserad på intervjuer med de aktörer som har varit aktiva i Leaderområdet för södra Bohuslän, där resultatet har tolkats utifrån de två begreppen governance och flernivåstyre. Studien visade på att det det fanns en samstämmighet i att Leader har blivit ett starkare begrepp och en legitimerad metod. Den strukturella förändringen av Leader upplevdes gå från öppen och flexibel till en mer strikt form. Urvalskriteriena, som används inför beslut, har blivit tydligare och fler och detta har inneburit att projekten ställs inför högre krav i den nuvarande perioden (2014-2020) än vad som upplevdes inledningsvis (2000-2007). De initiala projektmedlen som Leader bistår med uttrycktes ha ett symboliskt värde som stärker projektidén. Det fanns en gemensam vision från aktörerna om att intressen för lokalsamhället skall styra besluten inom den lokala aktionsgruppen, LAG. Flera informanter liksom forskning inom området, framhöll vikten av att se till de samhälleliga intressena för att skapa relevanta projekt. En framgångsfaktor visade sig vara att personer som företrädde de olika sektorerna under fler tidsperioder medförde att erfarenheter kunde tas tillvara på ett bättre sätt. Både flernivåstyre och governance genomsyras av konsensus som fanns integrerat inom beslutsprocessen. Leaderområdet lyckades genomföra projekt som efter avslutad projekttid och drevs vidare i samma regi eller på ett nytt sätt. Leader som metod visade sig ge varaktiga effekter på projekt som hade ett tydligt underifrånperspektiv.Since the entrance in the European union in 1995, Sweden has used a method to coordinate aktivities in accordance to ekonomic development in rural areas, Leader. The method rest on a partnership between private, voluntary and public sector. In agreement, these three sectors decide a strategy of the area and choose project that harmonize with its objectives. The purpose of this study has been to understand changes within the Leadermethod over time and how it has affected the participants within the method. The stude is based on a qualitative analysis of interviews, strategies and evaluations from three selected periods in the south of Bohuslän. The results have been analysed in terms of governance and multilevel governance. The study showed that there is an overal concent that Leader as a method has improved. It has also increased in legitimacy. The participants, from all three sectors, showed that they share a common vision, to let the need of the local society govern decisions. A founding aspect in both governance and multi-level governance is consensus. The study showed that consensus has been well integrated in the periods and futhermore been increased in every period. This is one key element to the development of more well completed projekts, all three sectors share the common vision. The initial grant that Leader contributes with has a symbolic value that enhances the idé of the project. The development of the structure of Leader moves towards a more rigid form. The criteria of what constitute a good projekt have developed to be more distinguished and also widen over these periods, which had the ambition of making it easier for the projects to be more well composed, hence more endouring. The participants ability to see what benifits the local society the most, become the essence of creating a good project. However, Leader has shown good example of that multi-level governance tend to make projects vital and continue after the expire of the projekt in Leader. It becomes clear that the bottum-up approach is a vital ingredient for the projekcts to succeed. One of the key factor of prosperous periods has been to gathered experiences from previous periods through the persons that reprecented the various sectors. It was important to integrate that knowledge into the present Leaderperiod (2014-2020). Longterm effects, rippes on water, are accomplished by allowing projects to be penetrated by the bottum-up approach

New ways to distribute food

Alternative food systems have grown increasingly for the last 20 years and are seen as a reaction to the distant relationship between consumers and the origin of food. The discussion about shorter food systems and short food supply chains (SFSCs) raises the question about finding alternative ways to organize around food systems. In recent years the use of digital ordering systems for buying food has increased in combination with the increased interest of the consumption of locally produced food. In Sweden the virtual food platform REKO-rings is growing, which connect consumers and producers both interested in selling and buying locally produced food using Facebook groups. The master thesis has a dual aim that at one side describes the development and organization of REKO-rings and on the other hand contribute to the understanding of the motives and underpinning values producers and consumers ascribe REKO-rings in Sweden. Based on those purposes I wanted to discuss the potential of REKO-rings to contribute towards alternative ways of distributing food in Sweden. The study used a mixed method approach combination with both qualitative and quantitative features, using an online survey and interviews with nine different REKO-rings in Sweden. The result showed that the number of members was increasing quickly. Throughout the time of the data gathering (ca 2 months) the member share increased from 78,461 members to 92,487 members, an increase of 18 % with five new REKO-rings. It also showed that REKO-rings were an easy way to connect local businesses and consumers using a flexible and social platform of communication. The result demonstrated that REKO-rings strengthen local communities and satisfy consumers and many different types of farmers, ranging from hobby farmers to full-time farmers. The virtual food platform of REKO-rings has the possibility to grow into an extensive social movement with prospects to challenge present conventional food systems.Utvecklingen av alternativa livsmedelssystem har ökat kraftigt de senaste 20 åren, som kan ses som en motreaktion till komplexa och industriella matsystem. Diskussionen om lokala matsystem och korta livsmedelskedjor (SFSCs) väcker frågan om att hitta alternativa sätt att organisera matproduktion. Under de senaste åren har användningen av digitala beställningssystem för att köpa mat ökat, samtidigt som intresset av att köpa lokalt producerad mat expanderat. I Sverige växer den virtuella matplattformen REKO-ringar, som använder Facebookgrupper för att förena konsumenter och producenter att köpa och sälja lokalproducerad mat. Den här magisteruppsatsen genomfördes som en kombinerad kvantitativ och kvalitativ studie. Syftet med studien var att å ena sidan beskriva utvecklingen och organisationen av REKO-ringar och å andra sidan utforska de motiv och underliggande värderingar som producenter och konsumenter tillskriver REKO-ringar. Baserat på dessa syften ville jag diskutera REKOringarnas potential för att bidra till alternativa sätt att distribuera mat i Sverige. Resultatet visade att antalet medlemmar i REKO-ringarna ökar snabbt. Under tiden studien utfördes (ca 2 månader) ökade medlemmens andel från 78 461 medlemmar till 92 487 medlemmar, en ökning med 18% och fem nya REKO-ringar tillkom. REKO-ringar var ett nytt och enkelt sätt att sälja och köpa närproducerade produkter. REKO-ringar inkluderade ett brett spektrum av typer av producenter i olika storlekar, från hobbyodlare till heltidsbönder. Konsumenterna upplevde en tydlig nytta med plattformen då den kopplade samman producenter och konsumenter på ett sätt som bidrog till att stötta lokala företag och därigenom stärka det lokala samhället. Den virtuella matplattformen REKO-ringar, har möjlighet att växa till en omfattande social rörelse som kan utmana nuvarande konventionella matsystem

Direct observation of decoupled Dirac states at the interface between topological and normal insulators

Several proposed applications and exotic effects in topological insulators rely on the presence of helical Dirac states at the interface between a topological and a normal insulator. In the present work, we have used low-energy angle-resolved photoelectron spectroscopy to uncover and characterize the interface states of Bi$_2$Se$_3$ thin films and Bi$_2$Te$_3$/Bi$_2$Se$_3$ heterostuctures grown on Si(111). The results establish that Dirac fermions are indeed present at the topological-normal-insulator boundary and absent at the topological-topological-insulator interface. Moreover, it is demonstrated that band bending present within the topological-insulator films leads to a substantial separation of the interface and surface states in energy. These results pave the way for further studies and the realization of interface-related phenomena in topological-insulator thin-film heterostructures.Comment: 9 pages, 5 figure

The expansion of stripped-envelope stars:Consequences for supernovae and gravitational-wave progenitors

Massive binaries that merge as compact objects are the progenitors of gravitational-wave sources. Most of these binaries experience one or more phases of mass transfer, during which one of the stars loses part or all of its outer envelope and becomes a stripped-envelope star. The evolution of the size of these stripped stars is crucial in determining whether they experience further interactions and their final fate. We present new calculations of stripped-envelope stars based on binary evolution models computed with MESA. We use these to investigate their radius evolution as a function of mass and metallicity. We further discuss their pre-supernova observable characteristics and potential consequences of their evolution on the properties of supernovae from stripped stars. At high metallicity we find that practically all of the hydrogen-rich envelope is removed, in agreement with earlier findings. Only progenitors with initial masses below 10\Msun expand to large radii (up to 100\Rsun), while more massive progenitors stay compact. At low metallicity, a substantial amount of hydrogen remains and the progenitors can, in principle, expand to giant sizes (> 400\Rsun), for all masses we consider. This implies that they can fill their Roche lobe anew. We show that the prescriptions commonly used in population synthesis models underestimate the stellar radii by up to two orders of magnitude. We expect that this has consequences for the predictions for gravitational-wave sources from double neutron star mergers, in particular for their metallicity dependence.Comment: Main text 17 pages, 7 figures, accepted for publication in Astronomy & Astrophysic