1,275 research outputs found
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
BlÄgröngrÄ system i kallt klimat
Det finns stora möjligheter och behov att kombinera urbaniseringens markansprĂ„k med grön urban infrastruktur och i det arbetet sĂ€kra en hĂ„llbar dagvattenhantering. Att som landskapsarkitekt arbeta med detta Ă€r viktigt eftersom markansprĂ„ken ökar mĂ€ngden hĂ„rdgjorda ytor i stĂ€der vilket samtidigt reducerar grön urban infrastruktur. Detta innebĂ€r i förlĂ€ngningen förlorade ekosystemtjĂ€nster och Ă€r problematiskt eftersom vi mĂ€nniskor Ă€r starkt beroende av dem. Större mĂ€ngd hĂ„rdgjord yta ökar dessutom den urbana avrinningen vilket i sin tur ökar översvĂ€mningsrisken och föroreningsgraden i dagvattnet. De rĂ„dande klimatförĂ€ndringarna innebĂ€r tillika att Sverige vĂ€ntas fĂ„ en ökad nederbördsintensitet och i kallt klimat, dĂ€r snö, is och tjĂ€le pĂ„verkar den urbana marken, Ă€r infiltrationsmöjligheterna i dagslĂ€get begrĂ€nsade under vintern. DĂ€rför Ă€r syftet med det hĂ€r arbetet att föreslĂ„ klimatanpassade Ă„tgĂ€rder för gaturum i kallt klimat gĂ€llande dagvattenhantering och grön urban infrastruktur. För att Ă„stadkomma detta sammanfattas dessa Ă„tgĂ€rder i ett platsspecifikt gestaltningsförslag pĂ„ Fabriksgatan i Ărnsköldsvik (i hĂ€rdighetszon fem) med tekniska typsektioner som grund.
Ett blÄgröngrÄtt system möjliggör multifunktionella ytor dÀr flera funktioner kan samexistera. Med dessa system kan trafik, dagvattenhantering och grön urban infrastruktur alla fÄ plats pÄ samma ytor. Huvudkomponenten i ett blÄgröngrÄtt system Àr makadam, krossad sten som inte innehÄller nÄgra nollfraktioner. Porositeten i detta material möjliggör utrymme för vÀxternas rötter, vatten och syre vilket i mÄnga fall inte finns i traditionella urbana vÀxtbÀddar. NÀr dagvattnet leds ned i makadambÀddarna har materialet ocksÄ en fördröjande, renande och magasinerande förmÄga vilket minskar översvÀmningsrisken i dagvattensystemet och förbÀttrar vattenkvaliteten i recipienterna.
Typsektionerna visar hur regnbĂ€ddar, skelettjordar för trĂ€d i hĂ„rdgjord yta och öppna förstĂ€rkningslager under hĂ„rdgjord yta skulle kunna byggas upp i kallt klimat. Fabriksgatan, som idag Ă€r totalt hĂ„rdgjord, skulle med gestaltningsförslaget bli en klimatanpassad gata. Gestaltningen utgĂ„r frĂ„n ett blĂ„gröngrĂ„tt system baserat pĂ„ typsektionerna och möjliggör för fler och nya vĂ€xter i Ărnsköldsvik. PĂ„ grund av systemens genomslĂ€pplighet hĂ„lls vinterfukt borta frĂ„n vĂ€xternas rötter vilket innebĂ€r att vĂ€xter med lĂ€gre hĂ€rdighetsangivelse Ă€n zon fem kan presenteras pĂ„ Fabriksgatan. Gestaltningsförslaget visar ocksĂ„ en förbĂ€ttrad dagvattenhantering eftersom 23% av Fabriksgatans yta utrustats med regnbĂ€ddar, detta innebĂ€r att gatans nya gestaltning skulle kunna magasinera 306 kubikmeter dagvatten. Detta innebĂ€r ocksĂ„ att den snö som faller i regnbĂ€ddarna 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 Ărnsköldsvik (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 plantsâ 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 Ărnsköldsvik. 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 gardensâ 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 frÄn 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 ĂÂŒg 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 LÀstringe, 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 ĂÂŒg As l-1 during the first round and 125-142 ĂÂŒg 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 (Âł 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 Âł 125 ÎŒg 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 Är har naturlig förekomst av höga halter arsenik (As) i grundvatten upp-mÀrksammats
bÄde internationellt och i Sverige. Flera bevis har lagts fram för arsenikens toxiska effekter i
dricksvatten. Den cancerogena effekten och nya möjligheter att mÀta lÄga halter gjorde att WHO
1993 sĂ€nkte det rekommenderade grĂ€nsvĂ€rdet frĂ„n 50 till 10 ÎŒg As l-1. I Sverige genomfördes
motsvarande sÀnkning 2003.
Flera undersökningar har visat att höga As-halter kan förekomma i grundvatten. I Sverige har
Socialstyrelsen ansvaret för tillsynsvÀgledning rörande hÀlsoskydd. Det innebÀr bland annat ett
ansvar för dricksvatten producerat i enskilda brunnar samt dricksvattenanlÀggningar och vattenverk
som i genomsnitt anvÀnder mindre Àn 10 m3 dricksvatten per dygn eller försörjer mindre Àn 50
personer. Socialstyrelsen publicerade 2006 en rapport dÀr man bland annat redogör för befintlig
kunskap om rening av arsenikhaltigt grundvatten och drar slutsatsen att kunskapen Àr begrÀnsad.
Detta examensarbete syftade till att genomföra en undersökning av avskiljningsgraden hos de pÄ
marknaden existerande filtertyperna för rening av arsenikhaltigt grundvatten och dricksvatten.
Dessutom har arsenikens geografiska fördelning i Sverige samt de faktorer som Àr viktiga för dess
förekomst och spridning sammanfattats i en litteratur-studie.
Undersökningen av arsenikavskiljning genomfördes i LÀstringe vattenverk cirka 4 mil NO om
Nyköping. RÄvattnet ifrÄn vattenverket var ett naturligt grundvatten som genomgick viss
förbehandling innan uttag till testet utfördes. As (III) tillsattes dÀrefter i form av en nyberedd
NaAsO2-lösning. Sju olika filter med varierande storlek testades. Tre filter var baserade pÄ
adsorption till titanoxid eller jÀrnhydroxid och ytterligare tvÄ filter hade en starkt basisk
jonbytarmassa (SBA) i kombination med jÀrn- eller aluminiumoxid. De ÄterstÄende tvÄ filtren
byggde pÄ omvÀnd osmos. Filtertestet lades upp i tvÄ omgÄngar om vardera 30 dagar. Inga sÀkra
slutsatser kan dĂ€rför dras om deras uthĂ„llighet. IngĂ„ende As-halt var 26-40,5 ÎŒg As l-1 under den
första omgĂ„ngen och 125-142 ÎŒg As l-1 under den andra omgĂ„ngen. Efter första omgĂ„ngen valdes de
fem mest effektiva filtren ut till andra omgÄngen. Med hjÀlp av magnet-ventiler och tidur reglerades
volymen vatten genom filtren per dygn sÄ att flödet skulle efterlikna ett hushÄlls
konsumtionsmönster över dygnet. En analys av vilka As-former som förekom i ingÄende vatten
visade att i princip all As (III) hade oxiderats till As (V). Oxidationen kan ha pÄskyndats av
förekommande Mn-oxider och mikroorganismer. DÀrmed antas att filtren försÄgs med ett vatten
innehÄllande bÄde As (III) och As (V).
Filtren med TiO2 - och Fe(OH)3 -granulat, samt Fe(OH)3 -impregnerad anjonbytare visade
tillfredstÀllande avskiljning av As (³ 97,3 %) med halter vÀl under riktvÀrdet (10 ug l-1).
Det stora filtret med omvÀnd osmos visade en lÀgre reningsgrad av As. UtgÄende As-halt var i
flertalet fall högre Ă€n riktvĂ€rdet dĂ„ den ingĂ„ende As-halten var Âł125 ÎŒg l-1. Detta filter av-skiljde
dÀremot flera andra Àmnen i hög grad. Det sÀmre resultatet berodde sannolikt pÄ att As tillsattes i
trevÀrd form.
Det Àr viktigt att analysera grundvatten eller rÄvatten som ska anvÀndas som dricksvatten med
avseende pÄ förekommande As-former, total As-halt, halter av andra Àmnen i anjonform, sÄsom
DOC samt pH vÀrdet inför valet av filterteknik. Kisel kan vara en konkurrent till As i filter baserade
pÄ adsorption till (hydr)oxider, och sulfat kan utgöra en konkurrent i anjonbytesfilter som bygger pÄ
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
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