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71 Uppsatser om Gradient - Sida 4 av 5

Increased growth in Norway spruce (Picea abies (L.) Karst.) through small annual additions of nitrogen (N) fertilizer

This project investigated how elevation and vegetation type influences variation in plant litter phenolic content and protein precipitation capacity among and within common plant species for two different vegetation types, heath and meadow, in a subarctic ecosystem in the Abisko region of northern Sweden. As nutrient availability generally decreases with increasing elevation as a result of decreasing temperature, I hypothesised that phenolic content would increase with elevation and be higher on the heath than the meadow. To test this, the total phenolic content and protein precipitation capacity was estimated in leaf litter from 13 species in both heath and meadow vegetation across an elevational Gradient ranging from 500 to 1000 meters above sea level (m.a.s.l.) in the study region. The results showed that elevation and vegetation type both had a strong impact on both variables. Total phenolic concentrations decreased with elevation for the meadow, and were greater for the heath than the meadow.

Simulering av inomhusklimat i lågenergihus

Värmeförbrukningen för småhus minskar varje år genom att hus med allt tätare och bättre klimatskal byggs. Vid en lägre värmeförbrukning är frågan om de traditionella metoderna för värme och ventilation är ett bra alternativ för att upprätthålla ett bra inomhusklimat eller kan nya effektivare metoder erhålla ett liknande inomhusklimat med mindre investeringskostnader.Detta examensarbete är en förstudie där inomhus klimatet studerats genom datorbaserade flödessimuleringar. I studien har en modell för att på ett enkelt sätt använda CFD simuleringar (datorstödda flödessimuleringar) för att studera inomhusklimatet genom att en modell har byggs upp i tre steg för att erhålla stabila resultat av ett lågenergihus framtaget av Glommershus med avseende på konvergens krav och turbulensmodell.Studier på olika lösningar för distribution av värme har undersökts genom att resultat från modeller med radiatorer, golvvärme samt en luftvärmepump för tre olika fall på utomhus temperatur. Resultatet betraktas med hänsyn till boverkets regler för nybyggnationer av småhus.I resultatet framkom att bygga upp modellen i tresteg är att föredra vid CFD-simuleringar för ett lågenergihus genom att en rad tidsbesparande detaljer görs. Även att CFD som simulerings verktyg kan användas för att utvärdera olika lösningar för värme och ventilation på ett smidigt sätt.Vid radiatorer och golvvärme visar resultatet på att temperatur Gradienterna horisontellt varierar mycket lite.

Avrinning från körbanor och hydrauliken hos stenfyllda dagvattendiken.

För ett regn med 10-års återkomsttid och 10 minuters varaktighet kommer att få en nederbördsökning på 4 % enligt den modell som används i P104 jämfört med modellen i P90 som användes vid projekteringen. Om intensitets och varaktighetskurvor ritas upp med hjälp av regndata från Uppsala, kommer det att medföra en nederbördsökning på 24 % jämfört med P90. Ökningar mellan P90 och P104 kommer inte att göra att kapaciteten hos magasinen överskrids eftersom ökningen är så liten. Dock så tyder studierna på att vattnet inte alls tar de vägar som har antagits vid projekteringen och som normalt antas vid dagvattenprojekteringar av detta slag. Det troliga är att större delen av den nederbörd som faller aldrig kommer att nå fram till dikena och infiltrera ner i dessa.Vid små nederbördsmängder kommer större delen av vattnet att infiltrera i stödremsan nära asfaltskanten.

Markanvändning och ekosystemtjänster i en gradient från borealt till alpint landskap ? Vilhelmina Model Forest

Begreppet ekosystemtjänster kan användas för att tydliggöra värdet av landskapets funktioner och därmed underlätta kommunikation mellan markanvändare då olika intressen konkurrerar. Emellertid finns det få studier som inkluderar en kvantitativ eller kvalitativ värdering av ekosystemtjänster på landskapsnivå. I detta arbete har markanvändning och ekosystemtjänster studerats i ett landskapsperspektiv, med Vilhelmina Model Forest (VMF) som studieområde. Den övergripande frågan i VMF är hur rennäring kan kombineras med andra markanvändningsintressen, huvudsakligen skogsbruk. Syftet med studien var att göra en kvantitativ värdering av markanvändningsintressen och ekosystemtjänster.

Värmeöverföring i bergvärmesystem : En numerisk analys av den ringformade koaxiala borrhålsvärmeväxlaren

The borehole heat exchangers of today suffer from poor thermal and hydrodynamic performance. The purpose of this thesis is to improve the performance of ground source heat pump systems and thermal energy storages by increasing the energy efficiency of the borehole heat exchangers. For this reason, the annular coaxial borehole heat exchanger (CBHE) has been analyzed. This type of heat exchanger is interesting in terms of both thermal and hydrodynamic performance. A model has been set up in the program Comsol Multiphysics in order to investigate the heat transfer characteristics along the borehole.

Översvämningskartering av Vombs ängar

Vomb meadows is an area well knows for its rich bird life. During the 19:thcentury until mid 20:th century, the meadows were flooded annually in order toincrease the hay yield. The river Klingavälsån situated along the west side of themeadows, used to be a shallow river, meandering across the landscape. In the1940?s the river was straightened and made deeper.

Selen och incidens av typ 2-diabetes - en systematisk översiktsartikel

Background: Type 2 diabetes is a disease which causes vascular damage, stroke and premature death.Oxidative stress may play a role in the development of insulin resistance and diabetes. Selenium is amineral involved in the protection against oxidative stress, and has been thought to be favorable in theprevention of the disease. However, this has changed since trials observed positive correlationsbetween high selenium levels and incidence of type 2 diabetes.Objective: To examine the studies that investigates seleniums effect on the incidence of typ 2 diabetesSearch strategy: Searches have been done in PubMed and Scopus.Selection criteria: Included studies were human studies in English/Swedish with RCT or cohortdesign with the aim to investigate the correlation between selenium and incidence of type 2 diabetes.Excluded studies were studies whose aim was to investigate the role of selenium in patients withexisting diabetes. Studies regarding pregnant women, animals or children and with in vitro design werealso excluded. Of the studies found in Scopus where MeSH terms were available, the ones who did notinclude relevant terms were excluded.Data collection and analysis: Studies were collected according to the aforementioned criteria.

Utveckling av en LC-MS-metod för analys av gamma-hydroxibutyrat, gamma-butyrolakton, 1,4-butandiol, amfetamin och metadon

In this project a LC-MS-method for the analysis of gamma-hydroxybutyrate, gamma-butyrolactone, 1,4-butanediol, amphetamine and methadone was developed.Initially, the efficiency of the ionisation of the analytes was evaluated with respect to the ionisation technique (ESI, APCI and APPI) and the composition of the mobile phase. In the next step a number of different columns was tested in order to find the one with the greatest potential for separation of the substances in question. Using the selected column, the separation was optimised by means of experimental design and the software The Unscrambler 7.8. The parameters studied were the flow rate, the column temperature and the mobile phase composition. The response variables were the resolution between the target compounds and the retention time of the last eluting compound.These experiments showed that, in order to obtain the best ionisation, the mobile phase should consist of 5 mM formic acid in water and acetonitrile.

Utveckling av beslutsstöd för kreditvärdighet

The aim is to develop a new decision-making model for credit-loans. The model will be specific for credit applicants of the OKQ8 bank, becauseit is based on data of earlier applicants of credit from the client (the bank). The final model is, in effect, functional enough to use informationabout a new applicant as input, and predict the outcome to either the good risk group or the bad risk group based on the applicant?s properties.The prediction may then lay the foundation for the decision to grant or deny credit loan.Because of the skewed distribution in the response variable, different sampling techniques are evaluated. These include oversampling with SMOTE, random undersampling and pure oversampling in the form of scalar weighting of the minority class.

En undersökning av framtidametoder för att säkra förband i produktion

The thesis is an examination of the methods that are appropriate and long-term choice to obtain clamping force and secure screw joints in production. The employer, Scania CV AB, transmission manufactures axle gears to all trucks produced in Södertälje. One of the most common assembly elements is screw joints, where the clamping force is essential to achieve a secure joint. Current methods to secure the joint is due much of the friction effect and is an indirect method to measure the clamping force. The clampforce accuracy becomes more widely with torque angle control.

Structure and tree diversity of lowland limestone forest on Seram Island, Indonesia

There have previously been very few studies of forests on Seram Island in the Eastern Indonesian archipelago and none before on lowland limestone primary forests. The COLUPSIA project on collaborative land use planning has therefore chosen Seram as one of two project sites. The objective of the COLUPSIA project is to establish collaborative and equitable land use planning. In order to achieve its objective the COLUPSIA project aims to improve understanding of traditional resource management and how it interacts with governmental systems, as well as enhancing knowledge about tropical landscapes and ecosystem services.The aim of this study was to contribute to the COLUPSIA project through describing lowland limestone forest on Seram Island in respect to (1) forest structure, (2) tree species richness and (3) tree species composition. We set up 5 plots, each of 0.2 ha, at one site, Mawalai, and collected data on tree variables (tree diameter ?10 cm) as well as for some other life forms and environmental data.

Development of real-time RT-PCR for the detection of human sapovirus in foods

Food-poisoning is a major health problem and an estimated half a million Swedes are food-poisoned annually, with acute gastroenteritis as a consequence. One of the major causes of contaminated foods is related to food- and waterborne viruses. To be able to trace back the source of contaminant, the method of detecting viruses must be specific and sensitive. No standardized method for detecting foods for sapovirus exists today. The aim of the work described in this bachelor thesis is to implement and opti-mize a real-time RT-PCR method for the detection of all genogroups of human sapovirus in foods.

Interactions between some plant-parasitic nematodes and Rhizoctonia solani in potato fields

The pathogenic fungus Rhizoctonia solani causes major economic losses for potato producers in Sweden. The producers, as well as advisors, have reported possible increases in severity of R. solani when free-living plant parasitic nematodes are present and active. There are several examples in the literature of interactions between pathogens where one, or both species, support or increase the damage made by the other organism. These complexes are important to investigate and to be able to forecast, since even low incidences of fungi or nematodes may result in an interaction of significance.

Rostfärgat slam i dränagesystem vid vattenkraftsanläggningar : orsaker och åtgärder

From embankment dams is something that has long been noticed and given rise to different questions. The most serious question is if the sludge is a result of inner erosion through the dam, and thus consists of material transported from the dam. Concerns have also been raised whether the sludge could interfere with the systems drainage capacity and thereby lead to high pore pressure in the dam, or if the measurement of seepage is disturbed, as the measuring is usually made via Thomson weirs, which could risk being blocked. The result of this investigation shows that the sludge is a result of the oxidation of iron by iron bacteria, and to the greater part consists of these oxides as well as the bacteria?s own structures. The iron oxidizing bacteria, FeOB, oxides ferrous iron to ferric as a part of their metabolism, and thereby create large quantities of iron(oxy)hydroxides.

Solljusbilder : Artificiella solljuseffekter i rum

Artificiella solljusbilder kan ge positiva ka?nslor och upplevas som naturligt solljus i interio?ra miljo?er. I en tid da?r ljusniva?er och standardva?rden prioriteras blir det unika och intressanta allt viktigare i ljusdesignen. Utifra?n ma?nniskans tendens att fo?redra det naturliga kan ett artificiellt ljus som imiterar det naturliga ocksa? ge va?lma?ende och harmoni fo?r oss.

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