• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 39
  • 30
  • 1
  • Tagged with
  • 72
  • 72
  • 18
  • 13
  • 12
  • 11
  • 9
  • 8
  • 8
  • 8
  • 8
  • 8
  • 7
  • 7
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Arkeologisk Textil : Om Norra Sveriges Textilier under Järnålder och Medeltid / Archaeological Textile : About Northern Swedens Textiles during the Iron Age and Middle Ages

Bergqvist, Madelene January 2020 (has links)
The aim of this essay is to get a wider perspective on the early production and usage of textiles in Northern Sweden during the Iron Age and Middle Ages (up until the 17th century). The work consists of collecting digital data of finds, their location and approximate date, and then place them in l'chaîne opératiore, and group the finds accordingly. The groups of the production chain is presented on distribution maps. The lack of finds in large areas shows that, from this study, everyone using textiles were not necessarily creating them from their own raw material.
42

Comparison of CO2 and DIC concentrations in bays with and without river discharge in an ice-covered lake

Rosendahl, Anna January 2020 (has links)
Many of the world’s lakes are located at high latitudes in the northern hemisphere where seasonal ice cover is common. The ice restricts lake-atmosphere gas exchange, causing an under-ice accumulation of CO2. However, there are few spatial under-ice CO2 studies of river influence on lakes. Here, I examine the river plume of a river-influenced bay and compare it to a control bay without river influence in lake Örträsk, a humic of 7 km2 lake in boreal Sweden. There was no relationship between CO2 or DIC and distance from the Vargån river outlet in Vargån bay, even though the CO2 and DIC concentration of the river was found lower in Vargån river (median CO2: 53,2 µM; DIC: 178 µM) than in Vargån bay (median CO2: 84,7 µM; DIC: 301 µM). The median values of the control bay were CO2: 92,7 µM and DIC: 345 µM. There was a negative relationship in CO2 concentration with distance in the control bay, but not in DIC. The control bay had a higher concentration of CO2 at 0-60 m distance than Vargån bay, but there was no difference at 70-180 m. The DIC concentration was higher in the control bay than in Vargån bay. I have reported lower CO2 and DIC concentrations in the river than in the lake, which is not in accordance with literature and is probably due to an earlier ice-melt in the river than in the lake. The negative CO2 relationship in the control bay is likely due to sediment respiration.
43

Norrbotniabanans möjligheter till ökad arbetspendling - En kvantitativ studie om Botniabanans effekter kan förutsäga Norrbotniabanans framtid

Berlinder Sjömark, Siri January 2023 (has links)
Passenger traffic for train journeys has been limited in northern Sweden due to the fact that the railway has mainly been used in industrial business. The establishment of Botniabanan enabled passenger traffic by train and created a train connection between the cities in the region. A continuation of Botniabanan quickly began to be planned so that the railway would continue along the Norrland coast, and the so-called Norrbotniabanan came into being. Today, northern Norrland is also facing one of the largest industrial investments in Sweden's history, which will require an increased workforce and supply of skills. In order to meet the demand for labor, Norrbotniabanan can provide a good opportunity for increased work commuting. An efficient and improved transport supply can in turn increase work commuting without people having to move to work. This in turn can create regional enlargement.  The purpose of the study is to investigate and analyze the effects Botniabanan had on commuting and further analyze and compare these with the effects that can be expected to occur with commuting through the establishment of Norrbotniabanan. The study is based on predictions about Norrbotniabanan and whether these can be expected to be achieved. This is then compared with whether the expected effects of Botniabanan were fulfilled. The establishment of Norrbotniabanan is then presented in a context of regional enlargement. The study has been carried out based on a quantitative method by processing quantitative data (register data) as well as carrying out literature studies and content analysis.  The study found that commuting has increased since the establishment of Botniabanan and that commuting mostly increased to Umeå municipality but also to Kramfors, which may be due to the municipality not belonging to Umeå's area of influence. In relation to this, commuting can be expected to increase with the establishment of Norrbotniabanan and in the same way that commuting mainly takes place to the larger municipalities such as Umeå, Luleå and Skellefteå. In order for Norrbotniabanan to achieve a greater increase in commuting than Botniabanan, the travel times need to be well planned. Provided that Norrbotniabanan has taken into account the reasons why the journey times for Botniabanan were not achieved, Norrbotniabanan has a good opportunity for a greater increase in commuting. Botniabanan can be declared to have achieved a regional enlargement, which Norrbotniabanan also makes possible. With the industrial investments in northern Sweden, Norrbotniabanan can create a stronger regional expansion than what Botniabanan did.
44

Utmaningar med passivhusstandard : En studie om små enbostadshus i norra Sverige / Challenges with passive house-standard : A study of small single-family homes in the north of Sweden

Ignberg, Johan January 2019 (has links)
Som följd av EUs direktiv om nya byggnaders energiprestanda ökar kraven på det svenska byggnadsbeståndet. Passivhusstandard är ett energiklassningssystem som kan nyttjas som verktyg för att nå energieffektiva byggnader. Att nå denna standard i små byggnader innebär dock enligt tidigare studier en utmaning och i Sveriges norra halva finns få passivhus, särskilt sådana som uppförts av egnahemsbyggare. Det gör det svårt att bedöma vad standarden innebär för den private beställaren av små enbostadshus, utifrån tidigare erfarenheter av motsvarande projekt. Denna studie syftar till att öka förståelsen för utmaningar vid byggande av små enbostadshus med passivhusstandard i norra Sverige. Det övergripande målet är att ta fram rekommendationer till beställare i norr som står inför val av energiprestandanivå för sina små enbostadshus, utifrån insikter som genereras av ett studieprojekt. Vilken energiprestanda som är rimlig för enbostadsbyggnader < 70 m2 i norr, är en av de frågor som svar söks på. Bedömningen görs utifrån svensk klassning av passivhus från Forum för Energieffektivt byggande, FEBY 18. Vidare ställs frågan hur utmaningarna ser ut för projekt av motsvarande omfattning där passivhusstandard eftersträvas. För att besvara frågorna har ett skarpt projekt valts som studieprojekt och utgångspunkt. Studieprojektet innebär en komplementbyggnad i ett plan om 55 m2 Atemp som planeras av egnahemsbyggare i Skellefteå för totalentreprenad. I studien ingår litteraturgenomgång om passivhusteknik och dess tillämpning i projekt samt fallstudie om Studieprojektet innefattande gestaltningsförslag, anbudsförfrågan till entreprenörer och intervjuer med dem. För kompletterande insikter till det studerade området, små enbostadshus med strävan mot passivhusstandard i norra Sverige,har även samtal skett med personer med erfarenhet av liknande projekt och personer med expertkunskap om passivhusstandarden. En av utmaningarna som identifierats är de tekniska lösningar som krävs för att teoretiskt uppnå energiprestanda motsvarande passivhus, FEBY Guld. Dessa fordrar en investeringskostnad som inte bedöms vara rimlig för byggnader av så liten skala. I studiens resultat framgår att den lägre nivån FEBY Silver är en mer rimlig målsättning för enbostadsbyggnader < 70 m2 i norr men att även den nivån kan innebära en utmaning för beställare. Hängivenhet hos beställare till energieffektiviserande lösningar är centralt för möjligheten att nå FEBY Silver. När dessa tekniska lösningar efterfrågas från en totalentreprenör med begränsad erfarenhet av energieffektiva småhus kan det vara svårt att fånga entreprenörers intresse. Dessutom kräver entreprenadformen relativt mycket arbete av entreprenörer vid kostnadskalkylering. Här identifieras utmaningar som spåras till att entreprenören bär funktionsansvaret som totalentreprenör vilket leder det till slutsatsen att beställare bör välja utförandeentreprenad för enbostadshus under 70 m2 i norra Sverige, med strävan mot passivhusstandard. Förslag på vidare studier innefattar att jämföra förutsättningar för låg energianvändning i olika, små byggnadstyper. Ytterligare förslag är att genomföra en ny anbudsförfrågan för Studieprojektet med utgångspunkt i resultatet från denna studie, för djupare insikter i kostnadsrelaterade utmaningar. / Stricter requirements for energy performance in buildings in Sweden is a result of a directive from EU. Passive house-standard is an energy classification system which can be used as a tool to reach energy efficiency in buildings. However, achieving passive house standard for small buildings is a challenge according to previous studies. Further, passive houses are few in the northern parts of Sweden, especially those built byprivate homeowners. Therefore, it’s difficult to assess what the standard means to private buyers of small single-family homes, based on previous experiences. This study aims to increase the understanding of challenges when building small single-family homes of passive house-standard in the north of Sweden. The main goal is to make recommendations to buyers of small single-family homes in the north who are facing the decision of what energy performance level to target, based on insights generated by a study project. One of the questions asked is -What is an appropriate level of energy performance of single-family homes <70 m2 in the north? The assessment is based is based on the Swedish classification system for passive houses, FEBY 18. The second question asked is -What are the challenges facing projects of this scale, where the passive house standard is sought? To answer the questions, a real project has been chosen for study and reference point. The Study Project is a 55 m2 Atemp single-storey house which is planned by private home-owners for a turnkey contract, on a real estate with an existing residence in Skellefteå. The study includes a literature review on passive house technology and its application in projects, as well as a case study of the Study Project containing a design proposal, a request for turnkey proposals from selected contractors and further contact with these through interviews. People with experience of relevant projects and people with expert knowledge of passive house standard have been contacted to reach additional insights within the studied area. Among the identified challenges are the building solutions and techniques which are required to reach passive house-standard, “FEBY Gold”. These solutions entail an investment cost that’s not considered to be reasonable for buildings of such a small scale. The study’s result shows that the lower energy level “FEBY Silver” is an attainable objective but still, this level as target can pose a challenge to the buyer.  A buyer’s dedication to energy efficient solutions is central for the prospect of having the Silver level within reach. When these building solutions are requested from a turnkey contractor with limited experience of energy-efficient, small houses, obstacles arise in making the project attractive for contractors as relatively much work is required when calculating costs. Here, challenges are identified that relates to the contractor being responsible for the function of the finished product, the house. This leads to the conclusion that private buyers should opt for other contract types than turnkey, for single-family homes < 70 m2in northern Sweden, when aiming for passive house standard.  Suggestions for further studies includes comparing the conditions for low energy use in different, small building types. Another suggestion is to carry out a new request for proposal of the Study Project and make adaptions according to the insights given by this study and thus, investigate the cost-related challenges further.
45

Characterising copy number polymorphisms using next generation sequencing data

Li, Zhiwei January 2019 (has links)
We developed a pipeline to identify the copy number polymorphisms (CNPs) in the Northern Swedish population using whole genome sequencing (WGS) data. Two different methodologies were applied to discover CNPs in more than 1,000 individuals. We also studied the association between the identified CNPs with the expression level of 438 plasma proteins collected in the same population. The identified CNPs were summarized and filtered as a population copy number matrix for 1,021 individuals in 243,987 non-overlapping CNP loci. For the 872 individuals with both WGS and plasma protein biomarkers data, we conducted linear regression analyses with age and sex as covariance. From the analyses, we detected 382 CNP loci, clustered in 30 collapsed copy number variable regions (CNVRs) that were significantly associated with the levels of 17 plasma protein biomarkers (p < 4.68×10-10).
46

I jordbrukets periferi : En studie om utvecklingen av agrar bebyggelse i marginella miljöer från stenåldern till järnåldern i Norra Sverige / In the periphery of agriculture : An approach to the development of agrarian farmsteads in marginal environments through the Stone Age to the Iron Age located in Northern Sweden

Eriksson, Love January 2019 (has links)
The development and establishment of agriculture in Northern Sweden has since long been believed to appear during the Late Iron Age, close to the Viking period, but recent finds from the Bronze Age in Umeå has opened up new discussion of when agriculture first emerged. Although too early to discuss where and when it developed, the material currently available on the topic allows for discussion for how it developed. By looking at sediment and soil conditions surrounding the settlements in combination with palaeoenvironments and past climate one aim was to try and search for settlement patterns in relation to agricultural potential, this was however unsuccessful. Cultivation practices were analysed using weed and wetland flora as well as agricultural indicators in pollen diagrams. Most settlements appear to focus firstly on animal husbandry and secondarily on cultivating crops, and they might have because of their coastal positioning also relied on fishing. The results confirmed previous hypothesis about the development of agriculture and cultivation practices in Northern Sweden during the Bronze and Iron Age, however, some issues remain concerning the lacking osteological material. / Utvecklingen och etableringen av jordbruk i Norrland har sedan länge verkat förekomma först under yngre järnåldern, nära vikingatiden, men nya fynd från bronsåldern i Umeå har öppnat upp diskussionen igen om när jordbruket först etablerade sig. Fastän det är för tidigt att behandla var och när, så tillåter det nuvarande materialet att börja till att diskutera hur jordbruket utvecklade sig. Kringliggande jordförhållanden har undersökts runtom bosättningar i relation till palaeomiljöer och forntida klimat med målet att söka efter bosättningsmönster i relation till potentialen att etablera jordbruk, men inga mönster framkom. Odlingsmetoder undersöktes genom ogräs och våtmarksväxter såväl som indikatorer på jordbruk och betning i pollendiagram. De flesta bosättningarna uppvisade ett fokus i första hand på djurhållning och i andra hand odling, samt att dess närhet till kusten och havet troligen såg ett utvecklat fiske. Resultaten bekräftade tidigare hypoteser om jordbrukets utveckling och odlingsmetoder i Norrland under Brons- och Järnåldern, dock återstår vissa problem beträffande det bristande osteologiska materialet.
47

Vegetation and climate during Weichselian ice free intervals in northern Sweden : Interpretations from fossil and modern pollen records

Hättestrand, Martina January 2008 (has links)
<p>In this thesis the Weichselian history of northern Sweden is investigated, with emphasis on vegetation and climate during ice-free intervals. The main method used has been pollen analysis of sediments from pre-Late Weichselian landforms. To interpret fossil pollen assemblages, comparisons with modern pollen spectra were made. Modern pollen data were retrieved through monitoring of annual pollen deposition at seven sites in northern Sweden, from the boreal forest to above the present forest-line of birch. Eight years of pollen monitoring is described and put in a larger context through comparison with monitoring data from Iceland, Svalbard, Norway and Finland. A study of sediment cores from the Riipiharju esker shows evidence of two ice free phases during the Weichselian glacial; Tärendö I and Tärendö II. The Tärendö II ice free interval includes large climatic shifts, previously not recognized, from relatively warm conditions with <i>Betula</i> as the dominating pollen taxon to cold conditions with dominance of <i>Artemisia</i> and Gramineae and back to warmer conditions again. Correlation alternatives of the north Swedish ice free intervals Tärendö I and II are: 1/ Brörup (MIS 5c; c. 105-93 ka BP) and Odderade (MIS 5a; c. 85-74 ka BP), respectively, or 2/ Odderade and early Middle Weichselian time (MIS 3; c. 59-40 ka BP). Of these, alternative 2 is regarded as the most likely. Interstadial sediments deposited in a Veiki moraine plateau during downwasting of a pre-Late Weichselian ice sheet include only <i>Betula</i> dominant pollen spectra, showing that the climate during formation of the Veiki moraine was relatively warm. According to stratigraphical correlation there are three possible alternatives for Veiki moraine formation. Either it was formed during 1/ early Tärendö I, 2/ early Tärendö II, or 3/ late Tärendö II. Alternative 3 implies growth of an intermediate ice sheet reaching the eastern limit of Veiki moraine distribution during the cold phase of Tärendö II.</p>
48

Diatoms as indicators of Holocene climate and environmental change in northern Sweden

Bigler, Christian January 2001 (has links)
<p>The objective of the thesis was to explore the potential of diatoms (<i>Bacillariophyceae</i>) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. Transfer functions based on unimodal species response models (WA-PLS) were developed for lake-water pH and mean July air temperature (July T), yielding coefficients of determination of 0.77 and 0.70, and prediction errors based on leave-one-out cross-validation of 0.19 pH units and 0.96 °C for lake-water pH and July T, respectively. The transfer functions were validated with monitoring data covering two open-water seasons (lake-water pH) and meteorological records covering the 20th century (July T). The good agreement between diatom-based inferences and measured monitoring data confirmed the prediction ability of the developed transfer functions. </p><p>Analysing a Holocene sediment core from a lake nearby Abisko (Vuoskkujávri), diatoms infer a linearly decreasing July T trend (1.5 °C) since 6,000 cal. BP, which compares well with inferences based on chironomids and pollen from the same sediment core. The lake-water pH inference shows a pattern of moderate natural acidification (c. 0.5 pH units) since the early Holocene, reaching present-day pH values at c. 5,000 cal. BP. By fitting fossil diatom samples to the modern calibration set by means of residual distance assessment within canonical correspondence analysis (CCA), the early Holocene (between 10,600 and 6,000 cal. BP) was identified as a problematic time-period for diatom-based inferences and, consequently, reconstructions during this period are tentative. Pollen-based inferences also show 'poor' fit between 10,600 and 7,500 cal. BP and chironomids probably provide the most reliable July T reconstruction at Vuoskkujávri, with 'poor' fit only during the initial part of the Holocene (between 10,600 and 10,250 cal. BP). </p><p>Possible factors confounding diatom-based July T inferences were investigated. Using detrended CCA (DCCA), Holocene sediment sequences from five lakes indicate that during the early Holocene, mainly physical factors such as high minerogenic erosion rates, high temperature and low light availability may have regulated diatom assemblages, favouring <i>Fragilaria</i> species. In all five lakes, diatom assemblages developed in a directional manner, but timing and scale of development differed substantially between lakes. The differences are attributed primarily to the geological properties of the lake catchments (with strong effects on lake-water pH), but other factors such as climatic change, vegetation, hydrologic setting and in-lake processes appear to regulate diatom communities in each lake differently. The influence of long-term natural acidification on diatom assemblages progressively declined during the Holocene with corresponding increase of the influence of climatic factors.</p>
49

Brood sex ratio and sex differences in Tengmalm’s owl : (Aegolius funereus)

Hipkiss, Tim January 2002 (has links)
<p>Males and females differ in morphology and behaviour, so that selection acts differently on the two sexes. This changes the relative reproductive success of males and females, and it is beneficial for parents to bias the sex ratio of their broods in favour of the sex with the best survival and breeding prospects. Differences between the sexes and brood sex ratio in Tengmalm’s owl (Aegolius funereus) in northern Sweden were investigated, using a molecular sexing technique based on PCRamplification of sex-linked CHD1 genes. Among owls caught during autumn migration, females were commoner than males, especially within juveniles. However, in contrast to earlier studies, it was shown that adult males sometimes undertake migratory movements indicatory of nomadism. Measurements of these owls revealed that sexual size dimorphism in Tengmalm’s owl is not as great as previously reported from studies carried out during the breeding season. Females were slightly larger (4% by mass) than males, probably owing to the different roles of males and females during breeding, when this dimorphism is greater. The size difference between male and female nestlings was found to be similar to that for adults in autumn, and to investigate whether this led to differential mortality, the effect of supplementary feeding on mortality of male and female nestlings was studied. Supplementary feeding reduced male mortality when vole abundance was low, and it was concluded that larger female nestlings out-competed their smaller brothers, who then suffered increased mortality when food was scarce. Recruitment of male nestlings into the breeding population declined with decreasing food supply at the time of fledging, a pattern not observed in females. Juvenile males were therefore more vulnerable to food shortage than females, both in the nest and after fledging. Mean brood sex ratio varied significantly among years characterized by different phases of the vole cycle and associated vole abundance. Broods were male-biased (63% males) in a year when the food supply was favourable during spring and summer, neutral (50%) in a year with an intermediate food supply, and female-biased (35% males) in a year when food was in short supply. Parents appeared to adaptively adjust the sex ratio of their broods according to the relative mortality risk and reproductive potential of sons and daughters.</p>
50

Diatoms as indicators of Holocene climate and environmental change in northern Sweden

Bigler, Christian January 2001 (has links)
The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. Transfer functions based on unimodal species response models (WA-PLS) were developed for lake-water pH and mean July air temperature (July T), yielding coefficients of determination of 0.77 and 0.70, and prediction errors based on leave-one-out cross-validation of 0.19 pH units and 0.96 °C for lake-water pH and July T, respectively. The transfer functions were validated with monitoring data covering two open-water seasons (lake-water pH) and meteorological records covering the 20th century (July T). The good agreement between diatom-based inferences and measured monitoring data confirmed the prediction ability of the developed transfer functions. Analysing a Holocene sediment core from a lake nearby Abisko (Vuoskkujávri), diatoms infer a linearly decreasing July T trend (1.5 °C) since 6,000 cal. BP, which compares well with inferences based on chironomids and pollen from the same sediment core. The lake-water pH inference shows a pattern of moderate natural acidification (c. 0.5 pH units) since the early Holocene, reaching present-day pH values at c. 5,000 cal. BP. By fitting fossil diatom samples to the modern calibration set by means of residual distance assessment within canonical correspondence analysis (CCA), the early Holocene (between 10,600 and 6,000 cal. BP) was identified as a problematic time-period for diatom-based inferences and, consequently, reconstructions during this period are tentative. Pollen-based inferences also show 'poor' fit between 10,600 and 7,500 cal. BP and chironomids probably provide the most reliable July T reconstruction at Vuoskkujávri, with 'poor' fit only during the initial part of the Holocene (between 10,600 and 10,250 cal. BP). Possible factors confounding diatom-based July T inferences were investigated. Using detrended CCA (DCCA), Holocene sediment sequences from five lakes indicate that during the early Holocene, mainly physical factors such as high minerogenic erosion rates, high temperature and low light availability may have regulated diatom assemblages, favouring Fragilaria species. In all five lakes, diatom assemblages developed in a directional manner, but timing and scale of development differed substantially between lakes. The differences are attributed primarily to the geological properties of the lake catchments (with strong effects on lake-water pH), but other factors such as climatic change, vegetation, hydrologic setting and in-lake processes appear to regulate diatom communities in each lake differently. The influence of long-term natural acidification on diatom assemblages progressively declined during the Holocene with corresponding increase of the influence of climatic factors.

Page generated in 0.301 seconds