• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 420
  • 228
  • Tagged with
  • 648
  • 601
  • 569
  • 559
  • 48
  • 47
  • 47
  • 44
  • 41
  • 39
  • 38
  • 38
  • 35
  • 32
  • 30
  • 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.
221

En bortprioriterad grupp : En kvalitativ studie kring de biologiska barnens betydelse i familjehem utifrån familjehemssekreterarnas arbete.

Kristiansson, Louise, Linder, Mikaela January 2017 (has links)
The purpose of this study is to illustrate how family home secretaries are discussing the conditions and importance of the biological children in foster families. Through this we want to gain an understanding of the subject and contribute with knowledge that can generate further research. Previous research shows that biological children are under prioritized in foster care. We were curious about what foster care secretary’s actually do for this group of individuals in their work. To get this information we interviewed six social workers who works with foster care. Our six informants were located in different municipalities in southern Sweden. The theoretical perspective we used were the norm of the core family, from private to public and the last theory we used were risk- and protection factors. The qualitative method for the study was semi- structured interviews that we transcribed and coded for our results. The results shows that the biological children gets often overridden due to the lack of resources and that the different municipalities argue differently about the need to support the biological children. The biological children in fosterfamilies has an important roll and meaning for the fosterchildren’s wellbeeing. Another result show that familychanges affects the biological children but the social workers dont’t reflect about that.
222

Water hyacinths (Eichornia crassipes) and their presence in Shire River, Malawi : Problems caused by them and ways of utilise them elsewhere

Mellhorn, Malin January 2013 (has links)
Malawi is one of many countries throughout the world struggling with massive amounts of water hyacinths (Eichornia crassipes) in the country’s fresh water resources.  In nutrient-rich ecosystems where the aquatic weed has no natural enemies it will reproduce very rapidly with the consequence that lakes become overgrown, water flow in rivers is reduced, and other water organisms becomes excluded. At the same time, the plants form a good breeding place for species carrying tropical diseases for example Malaria and Bilharzia. Water hyacinths are usually more of a problem for poorer countries since there are often great economic losses caused by the weed and to control their relative abundance is costly. In Malawi, 99 % of the produced electricity is based on water resources, mainly through hydropower turbines in the main river, Shire River. Water hyacinths, aggregated as islands, floating along the river and clogging the turbines cause repeated electricity black-outs and approximately 140 megawatt power is lost every day. To counter the weed interference with the electricity supply, there are great amounts of water hyacinths harvested every day and dumped along the road, with no further disposal plan. In this report, soil from one local dumping area is analysed to determine if such places are leaching nutrients or metals to the surrounding environment.  Water hyacinths contain naturally high values of nutrients and farmers use these harvested plants as a green manure to improve soil properties on agricultural land. This paper aims to examine levels of metal in water hyacinths used as green manure. This is of interest since water hyacinths have the ability to effectively absorb substances from the water body which could pose a risk for potentially toxic elements (PTEs) to accumulate in the agricultural soil and subsequently in crops. Sampling and analyses were carried out with standard methods. Metal and nutrient levels in the analysed samples were obtained through detection with atomic absorption spectrophotometry (AAS), ion chromatography (IC) and UV/VIS spectrophotometry at the Department of Chemistry of Chancellor College in Zomba, Malawi. None of the investigated metal ions (Cr, Pb, Cd) were found in the analysed water hyacinths and since soil sampling was done during the dry season this thesis cannot determine if the dumping areas are leaching nutrients. Relatively high amounts of total phosphorus were found in the plants. Overall, the conclusion is that there is no risk of using water hyacinths harvested in Shire River as a green manure on agricultural land.
223

Direct poly(A) RNA nanopore sequencing on the freshwater duck mussel Anodonta anatina following exposure to copper : A pilot study

Engström, Erik January 2019 (has links)
Aquatic ecotoxicology is the study of toxic chemicals and its effects on aquatic biological systems with the aim of minimising threats to human health and ensure self-sustained ecosystems. Freshwater bivalves are excellent sentinels for use in ecotoxilogical research due to their filter feeding properties, stationary lifestyle and inability to regulate body temperature. This project aimed to assess the feasibility and use of nanopore sequencing, a real-time single-molecule sequencing technology in comparative expression analysis by sequencing transcriptomic RNA from the freshwater mussel Anodonta anatina following exposure to copper. RNAs were extracted from 80 mg hepatopancreas tissue, followed by poly(A) RNA selection. Furthermore, the poly(A) RNA was used to construct a nanopore sequencing library. Sequencing a total amount of 560 ng poly(A) RNA over the course of two separate runs generated 239,448 reads, in which 75% of the reads were obtained during the first run (control) and 25% of the reads were obtained during the second run (case). The median read lengths ranged between 534-650 nucleotides, with a base call accuracy <90%. Due to the big differences in sequence data output between the two sequencing runs, the data was ineligible for comparative analysis. The findings conclude that nanopore sequencing is capable of generating longer read lengths when compared to other sequencing platforms. However, the technology is error-prone in terms of accurate base call identifications and relies on other platforms for error corrections. Future advances include de novo transcriptome assembly for efficient use of Anodonta anatina as a bioindicator in aquatic ecotoxicology.
224

DNA extraction comparisons between  fresh and boiled Atlantic Salmon (S. salar) tissues.

Bernal, Victoria January 2019 (has links)
Barcode identification is a method that uses genetic information to differentiate species. Because of its general versatility it can be applied to contexts from archaeology to the food industry. Atlantic salmon (Salmo salar) is a fish species commonly hunted in modern times and has been found in archaeological settings. However, barcoding requires enough quality DNA for amplification and abiotic exposure tends to degrade it. High temperatures, such as when boiling, can diminish DNA quality. The extent of DNA degradation between fresh and boiled tissues and whether all tissues retain the same amount of DNA is unclear. In this study DNA was extracted from S. salar tissues fins, muscle, bones and scales without treatment and with boiling treatment. DNA concentrations between fresh and boiled bones were not significantly different, nor were comparisons between samples with the same treatments. Muscles had higher DNA concentrations when boiled and fins had higher when fresh. These findings show that regarding certain tissue types can be expected to better retain DNA concentrations after boiling.
225

Aggressionsbeteendet mellan harr, lax och öring – potentiellpåverkan på återutsättning av lax / The agonistic behavior between grayling, salmon and trout – potential effectsrelated to the reintroduction of salmon

Nylund, Rebecca January 2019 (has links)
Det finns många studier på hur främmande arter påverkar en arts återinförsel, men det finns fåsom har gjorts om infödda arters påverkan. Atlantlax (Salmo salar) kunde en gång i tidenmigrera från Vänern i Sverige till Klarälven på den norska sidan. Det kan den inte idag, menidag talas det om att återinföra laxen till Klarälven i Norge så att den kan utföra hela sinmigrationsrutt igen. I den älven har laxen en gång i tiden koexisterat med sina konkurrenterharr (Thymallus thymallus), och öring (Salmo trutta) men idag är frågan hur denkonkurrensen mellan dessa tre arter kan komma att påverka återinförseln av lax. För att få enbättre bild av hur utgången för en potentiell återintroduktion kan se ut, så var syftet meddenna undersökning att ta reda på mot vilken art dessa tre arter främst riktade sinaaggressionsbeteenden mot. I akvarieförsök med juvenila individer av dessa tre arter harundersökningarna tagit plats och aggressiva beteenden filmades när arterna var i olikakombinationer. Resultatet visade att harr var den mest aktiva av de tre arterna och lax denminst aktiva, samt att lax blev dominerad utav både harr och öring. Resultatet i denna studietyder på att en återintroduktion av lax kan innehålla svårigheter, men i naturen är ett habitatmer komplext än i ett akvarium vilket kan ge ett annat resultat som kanske gör enåterintroduktion mer framgångsrik. / There are many studies about how the effects from exotic species could affect a reintroductionof a species, but there are only a few that have been made about the effects from nativespecies. The Atlantic salmon (Salmo salar) could historically speaking, migrate from lakeVänern in Sweden to the River Klarälven in Norway. Today it cannot do this, but there is anongoing discussion about reintroducing the salmon to the Norwegian side of River Klarälven,so it once again can swim along its entire migration route. In that river, the salmon used tocoexist with its competitors, grayling (Thymallus thymallus) and trout (Salmo trutta), buttoday the question is how competition between these three species could affect thereintroduction of salmon. To get a better understanding of the outcome of a possiblereintroduction, the purpose of this study was to ascertain which species these three speciesmainly directed their agonistic behavior towards. The study took place in aquariums withjuvenile individuals of the three species. Agonistic behavior was filmed when the specieswere together in different combinations. The results show that grayling is the most active ofthe three species, while salmon is the least active, and salmon was dominated by both graylingand trout. The results from this study indicates that a reintroduction of salmon might befraught with problems, but in nature a habitat is more complex than in an aquarium, whichmeans that in nature the results could be different, which might make a reintroduction moresuccessful.
226

Visual reactions to auditory stimulus by the jumping spider Phidippus princeps (Araneae, Salticidae)

Denbaum, Philip January 2019 (has links)
Jumping spiders (Family Salticidae) are known for their exceptional vision, including color vision and spatial acuity. Salticids use their vision in many behaviors, including predation and courtship. Recently evidence of their ability to sense airborne vibrations, i.e. sound, was published. I used a specialized jumping-spider-specific eyetracker to study the visual reaction of the retinas of the jumping spider Phidippus princeps when exposed to the sound of a predator. I used a generic wasp sound, previously shown to induce a startle response, as stimulus and played it from different directions. The spiders showed strong reactions to the sound stimulus by large increases in retinal movement when exposed to the stimulus, and they showed no habituation to the stimulus over three rounds of exposure. However, I found no indication that the direction of retinal movement corresponded to the location of the sound source. Future experiments may examine whether spiders are primed to search for particular types of images by cross-modal cues such as sound and if they can determine the direction of a sound source.
227

Skogsmyror (Formica rufa-gruppen) i monokulturell granskog och i nyckelbiotoper med hög andel gran i södra Sverige

Petersson, Germund January 2019 (has links)
Ants belonging to the Formica rufa group (wood ants) and their mounds have a large impact on forest ecosystems. This makes them considered keystone species. Several species of wood ants are threatened globally according to the IUCN red list. In this degree project mound densities and mound volumes were evaluated and compared between Norway spruce monocultures and high part Norway spruce woodland key habitats (WKHs) in southern Sweden. There were no significant differences in neihter mound densities nor mound volumes between the two stand types. However, mounds were distributed differently within the stand types and tree density correlated negatively to mound density in both stand types. Wood ant mounds were absent in the interior of monoculture stands, except in light gaps, while several mounds where located in the interior of WKHs. My results suggest that there is not enough light in the interior of monocultures in southern Sweden for wood ants to be able to colonize. Large monoculture areas may lack wood ants if gaps are missing. Therefore, gaps inside monocultures should be made more common in Swedish forests in order to benefit wood ants in production forests. Small clearcuts seem to benefit wood ant dispersal in monocultural stands. Therefore, smaller clearcuts should be preferred over the large areas presently clearcutted due to the negative effects of large clearcuts on wood ants.
228

The limits of species recognition: heterospecific song learning in pied flycatchers

Triantafyllidou, Maria January 2016 (has links)
The closely related species pied flycatcher (Ficedula hypoleuca) and collared flycatcher (F. albicollis) co-occur on the Swedish island of Öland, where they compete over similar resources. The majority of male pied flycatchers have been found to incorporate elements of the collared flycatcher song in their repertoire. Given that birdsong is partly inherited and partly learned, the relative contribution of genetic predispositions versus acoustic stimuli varies across different species. The results show that in pied flycatchers, song acquisition is tightly correlated with imprinting, and can therefore be greatly influenced by heterospecific tutors in their surroundings, i.e. male collared flycatchers. I found that pied males are capable of not only memorizing collared song elements, but also producing them with high fidelity. Thus, I infer that pied flycatchers are characterized by a high degree of vocal plasticity.
229

Arbete kring barn vid familjehemsplacering : Socialsekreterares förhållningssätt gällande arbete kring barns utveckling vid familjehemsplacering / Relationships during foster care : Social service work with a child’s identity formation and development during foster care

Boström, Isak, Koivisto, Alexander January 2019 (has links)
The aim of this study was to examine how the social service workers reflect on their work in cases when a child is placed in foster care. Both with people who works with the child before the decision and the placement is made and the people who works with it after after the placement. The study examined how social workers worked with the aspects of relationships and contact, both between social worker and the biological parent but also between the child and the child's biological parents. This study provides a understanding of how social workers reflect on concepts such as attachment and relationships during the process of foster care, both before and after the placement is done. The investigation has a qualitative approach and contains eight semi-structured interviews with social workers who are a part of the process either before or after the placement is done. Four interviews have been conducted with social workers that are involved before the placement and four interviews have been conducted with social workers who are involved after the placement. In the thematic data analysis of the empirical interview material was coded. At first, an initial coding was done. After that a selective coding was carried out where the codes that were recurrent and significant for the study was made into the themes that made the results of the study.   The results of the study show that the process of placing a child in foster care is complex. Attachment, relationships and the juridical process was aspects of this process that the participants considered important. A child's attachment was something they considered important because it was of great importance for a child's development. The relationships were something that the participants considered to be a challenge to work with. The clients need to get a new social worker after the placement which complicates the work regarding relationships. There is also a conflict of interest and a difficulty to cooperate between the parties. The juridical process is an aspect were the participants considered needed improvement. The participants considered them to have to minimal of an influence on the process. They considered that they needed more influence because the people who works in the legal system do not have the same amount of knowledge considering a child’s development that the participant have.
230

Population dynamics and management strategies of stray and free-ranging dogs in Bor, Serbia

Skrijelj, Lejla January 2019 (has links)
Dogs are one of the most widespread carnivore and the third most invasive mammal, after cats and rodents. Stray dogs affect wildlife negatively by predation, disturbance, disease spreading, competition and hybridization with other wild canids. Even in urban environments stray dogs cause problems such as disturbance, pollution, traffic accidents, bites and risk of disease spreading. Serbia is one of many countries in the Balkan region that has a problem with overpopulation of stray dogs. The aim of this study is to investigate the population dynamics of stray dogs in Bor, Serbia and discuss different dog population management strategies. A total of 361 stray dogs were registered, 111 male dogs, 85 female dogs and 165 dogs with undetermined sex. 55 dogs (15.23%) were estimated to be older than 7 years old, 262 dogs (72.57%) were estimated to be between 3-7 years old, 30 dogs (8.31%) were estimated to be between 6-24 months old and 14 dogs (3.87) were estimated to be between 0-6 months old. No dogs showed any signs of rabies or CDV (canine distemper virus) and 241 stray dogs (66.75%) seemed healthy. 120 stray dogs (33.25%) did however have some kind of impaired health. To achieve a stop in the population increase,70% sterilisation rate is required and to teach responsible dog ownership. The stray dogs showed different reactions towards people, 164 dogs (45.42%) were neutral and 100 dogs (27.70%) showed no fear or aggression towards humans and gladly interacted. Since the dogs are highly accessible, they would be acceptable for a TNR (trap-neuter-release) program and male dogs need to be prioritised considering their dispersal patterns. / Hundar är en av de mest spridda karnivorerna och det tredje mest invasiva däggdjuret, efter katter och gnagare. Gatuhundar påverkar vilda djur negativt genom predation, störning, spridning av sjukdomar, konkurrens och hybridisering med andra vilda hunddjur. Även i urbana miljöer har gatuhundar en negativ påverkan, genom störning, förorening, trafikolyckor, bett och sjukdomsrisk. Serbien är ett av många länder i Balkanregionen som har för stora populationer av gatuhundar. I detta arbete undersöks populationsdynamiken hos gatuhundar i Bor, Serbien och diskuterar olika metoder för att hantera gatuhundpopulationen. Totalt inventerades 361 gatuhundar, 111 hanar, 85 honor och 165 med obestämt kön. 55 hundar (15.23%) uppskattades vara äldre än 7 år, 262 hundar (72.57%) uppskattades vara mellan 3-7 år, 30 hundar (8.31%) uppskattades vara mellan 6-24 månader gamla och 14 hundar (3.87) uppskattades vara mellan 0-6 månader gamla. Inga hundar visade tecken på rabies eller CDV (canine distemper virus) och 241 gatuhundar (66.75%) föreföll friska. Däremot visade 120 hundar (33.25%) någon typ av nedsatt hälsa. För att uppnå ett stopp i populationsökningen krävs minst 70% steriliseringstakt samt att man lär ut ansvarsfullt hundägande. Gatuhundarna visade olika reaktioner mot människor, 164 hundar (45.42%) var neutrala och 100 hundar (27.70%) visade ingen rädsla eller aggression för människor och interagerade gärna. Eftersom gatuhundarna är lättillgängliga, skulle de kunna ingå i populationshanteringar som TNR (trap-neuter-release) och hanhundar bör prioriteras med tanke på deras spridningsmönster.

Page generated in 0.0321 seconds