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

Blågröngrå system i kallt klimat

Det finns stora möjligheter och behov att kombinera urbaniseringens markanspråk med grön urban infrastruktur och i det arbetet säkra en hållbar dagvattenhantering. Att som landskapsarkitekt arbeta med detta är viktigt eftersom markanspråken ökar mängden hårdgjorda ytor i städer vilket samtidigt reducerar grön urban infrastruktur. Detta innebär i förlängningen förlorade ekosystemtjänster och är problematiskt eftersom vi människor är starkt beroende av dem. Större mängd hårdgjord yta ökar dessutom den urbana avrinningen vilket i sin tur ökar översvämningsrisken och föroreningsgraden i dagvattnet. De rådande klimatförändringarna innebär tillika att Sverige väntas få en ökad nederbördsintensitet och i kallt klimat, där snö, is och tjäle påverkar den urbana marken, är infiltrationsmöjligheterna i dagsläget begränsade under vintern. Därför är syftet med det här arbetet att föreslå klimatanpassade åtgärder för gaturum i kallt klimat gällande dagvattenhantering och grön urban infrastruktur. För att åstadkomma detta sammanfattas dessa åtgärder i ett platsspecifikt gestaltningsförslag på Fabriksgatan i Örnsköldsvik (i härdighetszon fem) med tekniska typsektioner som grund. Ett blågröngrått system möjliggör multifunktionella ytor där flera funktioner kan samexistera. Med dessa system kan trafik, dagvattenhantering och grön urban infrastruktur alla få plats på samma ytor. Huvudkomponenten i ett blågröngrått system är makadam, krossad sten som inte innehåller några nollfraktioner. Porositeten i detta material möjliggör utrymme för växternas rötter, vatten och syre vilket i många fall inte finns i traditionella urbana växtbäddar. När dagvattnet leds ned i makadambäddarna har materialet också en fördröjande, renande och magasinerande förmåga vilket minskar översvämningsrisken i dagvattensystemet och förbättrar vattenkvaliteten i recipienterna. Typsektionerna visar hur regnbäddar, skelettjordar för träd i hårdgjord yta och öppna förstärkningslager under hårdgjord yta skulle kunna byggas upp i kallt klimat. Fabriksgatan, som idag är totalt hårdgjord, skulle med gestaltningsförslaget bli en klimatanpassad gata. Gestaltningen utgår från ett blågröngrått system baserat på typsektionerna och möjliggör för fler och nya växter i Örnsköldsvik. På grund av systemens genomsläpplighet hålls vinterfukt borta från växternas rötter vilket innebär att växter med lägre härdighetsangivelse än zon fem kan presenteras på Fabriksgatan. Gestaltningsförslaget visar också en förbättrad dagvattenhantering eftersom 23% av Fabriksgatans yta utrustats med regnbäddar, detta innebär att gatans nya gestaltning skulle kunna magasinera 306 kubikmeter dagvatten. Detta innebär också att den snö som faller i regnbäddarna inte behöver forslas bort och deponeras och 472 kubikmeter snö skulle magasineras i februari.There are great opportunities and needs to combine the land claim of urbanization with green urban infrastructure (GUI) and in that process ensure sustainable stormwater management. As a landscape architect, it is crucial to work with this since GUI often is replaced by paved surfaces when cities change through densification or expansion. The loss of GUI means that urban ecosystem services, which we humans are strongly dependent on, are lost. A larger amount of paved surfaces also increases the urban runoff, which in turn adds to the risk of flooding as well as the degree of pollution in stormwater. With the climate changes occurring, an increasing precipitation intensity is expected in Sweden and the infiltration capacity of stormwater during winter is low due to snow, ice and frozen ground in the areas in cold climate. The objective of the project is to present climate-sustainable solutions regarding stormwater management and GUI in cold climate. To accomplish this a site-specific design proposal for Fabriksgatan in Örnsköldsvik (in hardiness zone 5) is presented and has technical type solutions as a basis. A blue-green-gray system (BGG-system) enables surfaces where multiple functions can coexist, traffic, stormwater management and GUI for example can all fit in the same area. The main component of a BGG-system is macadam, crushed stone without small fractions. The porosity of the macadam enables space for the plants’ roots, water, and oxygen, which in many cases is not found in traditional urban plant beds. When the stormwater reaches the macadam, the material also has a delaying, purifying, and storing ability of the water, which reduces the risk of flooding in the stormwater system and improves the water quality in the recipients. The type solutions show how rain gardens, skeletal soil for trees in paved surfaces and structural soil under paved surfaces can be built in cold climate. With the design proposal Fabriksgatan, which today is totally paved, would become a climate-adapted street. The design builds upon a BGG-system based on the type solutions and enables more and new vegetation in Örnsköldsvik. Due to high permeability in the systems, a satisfying oxygen level for the plant roots occurs, which means that plants with lower hardinesszone than zone five can thrive on Fabriksgatan. The design proposal also shows improved stormwater management as 23% of Fabriksgatan's area is equipped with rain gardens, this means that the street's new design could store 306 cubic meters of stormwater. During wintertime, snow can also be stored on the rain gardens’ surface which reduces the amount of snow that needs to be removed and deposited. In February, 472 cubic meters of snow would be stored on Fabriksgatan (instead of zero)

A spin- and angle-resolving photoelectron spectrometer

A new type of hemispherical electron energy analyzer that permits angle and spin resolved photoelectron spectroscopy has been developed. The analyzer permits standard angle resolved spectra to be recorded with a two-dimensional detector in parallel with spin detection using a mini-Mott polarimeter. General design considerations as well as technical solutions are discussed and test results from the Au(111) surface state are presented

Hybrid workers describe aspects that promote effectiveness, work engagement, work-life balance, and health

While a significant number of employees want a hybrid workplace solution that combines onsite and remote work, many employers require their employees back to the conventional office. This discrepancy can partly depend on the prevailing knowledge gap regarding success factors for performance and work-life balance (WLB) in the hybrid work context. To fill this knowledge gap, we used a reflexive thematic analysis to explore the suggestions of success factors for collaboration, work-related health, and WLB in 33 hybrid workers. The success factors suggested by our participants were formed into four themes: (i) Combining onsite and remote work environments supports work effectiveness, (ii) Socialization and collaboration onsite and remotely promotes work engagement, (iii) Suitable ICT-solutions, digital maturity, and structured communication promote work engagement and effectiveness, and (iv) Workplace flexibility, empowerment, and personalized strategies promote work-related health and WLB. Overall, our results indicate that employees find that the hybrid work model can be optimal since it overcomes the shortcomings of onsite and remote work environments, respectively. Our results also suggest that a sustainable hybrid work-life can be achieved through a combination of common strategies at the organizational level and individual strategies at the personal level

Naturlig förekomst av arsenik och avskiljning av arsenik från grundvatten

During the last few years the presence of high arsenic (As) concentrations in ground water has been of major concern both internationally and in Sweden. Much evidence has been reported about toxic effects caused by arsenic. The carcinogenic effects and the possibility to measure the toxic impacts at low concentrations made the World Health Organisation (WHO) to reduce the guideline value from 50 to 10 μg l-1 in 1993. In Sweden the corresponding reduction was implemented in 2003. Several surveys in Sweden have shown that high arsenic concentrations may occur in ground water. The National Board of Health and Welfare is responsible for guidance and supervision of health protection. This responsibility covers privately owned wells and drinking water facilities that produce less than 10 m3 drinking water per day or support less than 50 people. In 2006 the National Board published a report in which they stated that the existing knowledge was limited concerning As removal from ground water. The objective of this master's thesis is to test some of the current commercially available filter techniques that are used to remove As from ground water. In addition, the national geographic distribution of arsenic and factors governing that distribution are discussed. Experiments regarding As removal by different filter techniques were carried out in a small water purification plant in the village of Lästringe, located 40 km NE of the city of Nyköping. Only ground water is used in the purification plant. In the experiments, As(III) was added to the water as NaAsO2. Seven different filters of varying size were tested, three of which were based on adsorption to titanium oxide or iron hydroxide, while another two were based on a strong base ion exchanger (SBA) combined with iron or aluminium (hydr)oxide. Finally, two filters were based on reversed osmosis. The filter experiment was set up in two rounds of 30 days each, and no firm conclusions can therefore be made about the endurance of the filters. The incoming water contained 26-40,5 μg As l-1 during the first round and 125-142 μg As l-1during the second round. After the first round the five most efficient filters were selected for the second round. Magnetic valves and timers were used to adjust the daily volume of water put through the filters in order to simulate the water consumption pattern of a household during 24 hours. A chemical analysis of existing As species revealed that almost all As(III) had been oxidized to As(V). The oxidation could have been catalyzed by manganese oxides together with bacteria. Consequently the filters were supplied with water containing both As(III) and As(V). The filters containing TiO2 and Fe(OH)3 granulates and the Fe(OH)3 impregnated anion exchanger had the highest As removal efficiency (³ 97,3 %), resulting in As concentrations well below the guideline value of 10 ug As l-1. The rather large reverse osmosis filter showed a smaller percentage of As removal and the As concentration in the water that had passed the filter was mostly higher than the guideline value whenever the incoming water had an As concentration ³ 125 μg l-1. However, the reverse osmosis filter removed many other substances to a large extent. The lower extent of As removal can probably be explained by a high fraction of As (III) occurring as arsenite. Before choosing the filter technique, it is important to analyse the groundwater with respect to existing As species, total concentration of As and other elements forming oxyanions, dissolved organic carbon (DOC) and pH. Silica (H2SiO40) can compete with arsenic for adsorption sites in filters based on metal (hydr)oxides. Sulphate (SO42-) can be a competitor through anion exchange in filters based on SBA.Under senare år har naturlig förekomst av höga halter arsenik (As) i grundvatten upp-märksammats både internationellt och i Sverige. Flera bevis har lagts fram för arsenikens toxiska effekter i dricksvatten. Den cancerogena effekten och nya möjligheter att mäta låga halter gjorde att WHO 1993 sänkte det rekommenderade gränsvärdet från 50 till 10 μg As l-1. I Sverige genomfördes motsvarande sänkning 2003. Flera undersökningar har visat att höga As-halter kan förekomma i grundvatten. I Sverige har Socialstyrelsen ansvaret för tillsynsvägledning rörande hälsoskydd. Det innebär bland annat ett ansvar för dricksvatten producerat i enskilda brunnar samt dricksvattenanläggningar och vattenverk som i genomsnitt använder mindre än 10 m3 dricksvatten per dygn eller försörjer mindre än 50 personer. Socialstyrelsen publicerade 2006 en rapport där man bland annat redogör för befintlig kunskap om rening av arsenikhaltigt grundvatten och drar slutsatsen att kunskapen är begränsad. Detta examensarbete syftade till att genomföra en undersökning av avskiljningsgraden hos de på marknaden existerande filtertyperna för rening av arsenikhaltigt grundvatten och dricksvatten. Dessutom har arsenikens geografiska fördelning i Sverige samt de faktorer som är viktiga för dess förekomst och spridning sammanfattats i en litteratur-studie. Undersökningen av arsenikavskiljning genomfördes i Lästringe vattenverk cirka 4 mil NO om Nyköping. Råvattnet ifrån vattenverket var ett naturligt grundvatten som genomgick viss förbehandling innan uttag till testet utfördes. As (III) tillsattes därefter i form av en nyberedd NaAsO2-lösning. Sju olika filter med varierande storlek testades. Tre filter var baserade på adsorption till titanoxid eller järnhydroxid och ytterligare två filter hade en starkt basisk jonbytarmassa (SBA) i kombination med järn- eller aluminiumoxid. De återstående två filtren byggde på omvänd osmos. Filtertestet lades upp i två omgångar om vardera 30 dagar. Inga säkra slutsatser kan därför dras om deras uthållighet. Ingående As-halt var 26-40,5 μg As l-1 under den första omgången och 125-142 μg As l-1 under den andra omgången. Efter första omgången valdes de fem mest effektiva filtren ut till andra omgången. Med hjälp av magnet-ventiler och tidur reglerades volymen vatten genom filtren per dygn så att flödet skulle efterlikna ett hushålls konsumtionsmönster över dygnet. En analys av vilka As-former som förekom i ingående vatten visade att i princip all As (III) hade oxiderats till As (V). Oxidationen kan ha påskyndats av förekommande Mn-oxider och mikroorganismer. Därmed antas att filtren försågs med ett vatten innehållande både As (III) och As (V). Filtren med TiO2 - och Fe(OH)3 -granulat, samt Fe(OH)3 -impregnerad anjonbytare visade tillfredställande avskiljning av As (³ 97,3 %) med halter väl under riktvärdet (10 ug l-1). Det stora filtret med omvänd osmos visade en lägre reningsgrad av As. Utgående As-halt var i flertalet fall högre än riktvärdet då den ingående As-halten var ³125 μg l-1. Detta filter av-skiljde däremot flera andra ämnen i hög grad. Det sämre resultatet berodde sannolikt på att As tillsattes i trevärd form. Det är viktigt att analysera grundvatten eller råvatten som ska användas som dricksvatten med avseende på förekommande As-former, total As-halt, halter av andra ämnen i anjonform, såsom DOC samt pH värdet inför valet av filterteknik. Kisel kan vara en konkurrent till As i filter baserade på adsorption till (hydr)oxider, och sulfat kan utgöra en konkurrent i anjonbytesfilter som bygger på SBA

The effect of mutated cysteine residues in von Willebrand factor

Von Willebrand factor (VWF) plays an important role in both primary and secondary hemostasis as a molecular glue between platelets and subendothelial structures, and as a carrier of FVIII. Mutations in VWF may cause von Willebrand disease (VWD), which is the most common bleeding disorder. It is characterized by symptoms ranging from very mild to severe bleeding. Mutations may influence the level of VWF (quantitative defect; type 1 or type 3) or may affect the function of VWF. Especially important for the generation of functional VWF is the formation of disulfide linked bonds. Firstly, intrachain linking is essential for the monomer structure. Secondly, interchain linking is necessary for both dimerization and multimerization of VWF. All 169 cysteine residues in the mature VWF subunit (8.2%) participate in these intra- or interchain disulfide bonds. The interaction between proVWF dimers ultimately yields high-molecular weight VWF that is active in primary hemostasis in the bloodstream.The main aims of the studies reported in this thesis were to examine how loss of cysteines located in different domains of VWF results in quantitative and qualitative VWF defects; how these mutations interfere with dimerization and multimerization; and how they influence intracellular routing, secretion and clearance of VWF.UBL - phd migration 201

Optimizing Wind Power Hosting Capacity of Distribution Systems Using Cost Benefit Analysis

The penetration of wind power into the electricity grid is growing significantly. A significant portion of this wind power is being installed in distribution systems, of which most are passively operated. Under this operating practice, wind power can only be admitted based on minimum load and maximum generation consideration. This severely limits the wind power hosting capacity of the system. Hence, the use of active-management strategies (AMSs) has been proposed to increase the hosting capacity of distribution systems. This paper incorporates AMSs into two optimization models whose objectives are to maximize the net benefit of distribution system operator and wind farm owner, respectively. The AMSs considered are wind energy curtailment, coordinated on-load tap changer voltage control, and reactive power compensation. The models development is based on a typical medium-voltage distribution system in Sweden although it can easily be adapted to other cases. The application of the model to a distribution system in Sweden shows an increase in hosting capacity of the distribution system by 78% with mere 2.6% curtailed energy. That is, the hosting capacity of the distribution system has almost been doubled by using AMSs