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  • 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.
71

Behavioural differences between and within retriever breeds

Brodd, Louise January 2016 (has links)
The retriever breeds have the same origin and have long been used as a gundog for hunting of game, mostly birds. However, recently the retriever breeds have become a popular pet and show dog. This have affected the breeding of the dogs as the same traits are not bred for a gundog and a pet or show dog. Breeds as the Labrador retriever consists of a field- and common-type. The aim of this study is to investigate any differences between and within five of the retriever breeds in behaviours as retrieving, search and game reaction. 64 dogs undergoing the field trial Description of Function- Retriever was video recorded and scores from 430 dogs that have undergone field trials was obtained. Both differences between and within breeds were found when analysing both the videos and scores. In the video analysis, the Flatcoated retriever showed the most retrieving behaviours and was the most passive. The Nova scotia duck tolling retriever was in both the video and score analyses the most active breed. The Labrador retriever scored high in game reaction. The field- and mixed-types had almost always higher scores in behaviours linked to hunting, compared to the common-type. This supports findings that recent selection in breeding have a larger effect on behaviour than the origin uses of the dogs.
72

Production of canine hepatocyte-like cells from stem cell sources

Gow, Adam George January 2014 (has links)
The cost of drug development is high with many drugs failing during toxicity testing. This is a particular problem in veterinary medicine where the pharmaceutical market size is so small that it may not be economically viable to develop drugs. The liver and specifically hepatocytes have a crucial role in drug metabolism via oxidation by cytochrome enzymes (CYP), conjugation and excretion into the biliary system. This drug metabolism is unpredictable between species as each has unique CYP profiles. Furthermore there is breed variation of CYP profiles within the canine species. The ability to produce an in vitro source of canine hepatocytes to model drug metabolism in this species and in different breeds would greatly reduce the expense of candidate drug testing. If an unlimited supply could be produced in vitro this would reduce the number of animals required in pre-clinical testing. The aim of this thesis was to produce an in vitro supply of canine hepatocyte-like cells from stem cell sources, namely hepatic progenitor cells (HPC), mesenchymal stem cells (MSC) or induced pluripotent stem cells (iPSC). Cultures of canine primary hepatocytes were produced to use as a gold standard, but also to develop and refine tests of hepatocyte characterisation and function. A panel of primers was developed for use in real time polymerase chain reaction (PCR) as well as optimising tests for low density lipoprotein (LDL) and indocyanine green uptake, albumin production, periodic acid- Schiff staining for glycogen and CYP activity using a luciferase-based system. As primary hepatocytes rapidly lost their defining characteristics and function in vitro, methods of maintaining function using CYP inducers and culture substrates were assessed. Isodensity centrifugation and magnetic-activated cell sorting was employed to isolate HPCs. Selection of cells from the non-parenchymal cell fraction with stem cell marker Prominin 1 demonstrated that these were keratin 7 positive, a HPC marker. Cells morphologically consistent with HPC appeared and expanded in culture after 2 weeks. On passaging, these cells failed to continue expanding, despite plating onto collagen, laminin, SNL feeder cells or using Kubota’s medium (known to allow rapid expansion of rodent and human HPCs). Canine adipose (Ad-MSC) and bone marrow-derived mesenchymal stromal cells (BM-MSC) were isolated post mortem. These were characterised as CD45, 105 and STRO-1 positive, CD11b, 19 and 45 negative cells which could be differentiated into adipocytes, chondrocytes and osteocytes based on staining characteristics and relative gene expression. Protocols published for other species were used to differentiate both Ad-MSC and BM-MSC towards a hepatocyte phenotype. Although a dramatic change in morphology and a reduction in vimentin gene expression were noted, suggesting a loss of mesenchymal phenotype, these protocols did not induce a hepatocyte phenotype. Pre-treatment with 5-Aza-2′-deoxycytidine to cause DNA demethylation and valproic acid to inhibit histone deacetylation also failed to allow transdifferentiation. A polycistronic vector containing Oct-4, c-Myc, Sox2 and Klf4 was successfully transfected into canine epidermal keratinocyte progenitor cells which became alkaline phosphatase positive and assumed a morphology consistent with iPSC. After colony selection and expansion, PCR evidence of plasmid presence was lost, colony morphology changed, and alkaline phosphatase activity reduced, consistent with vector expression factor and pluripotency loss. Canine iPSCs produced by lentiviral method were then differentiated towards hepatocyte phenotype using a published protocol for mouse and human iPSC. These cells were then assessed for hepatocyte characteristics using the developed reagents and primers. These cells demonstrated increased gene expression and morphology consistent with differentiation towards a hepatocyte-like phenotype. This thesis demonstrates successful culture of canine primary hepatocytes and validation of tests of hepatocyte phenotype. This provides a basis for optimising primary hepatocyte function in vitro and assessment of the success of differentiation protocols on stem cell sources. Canine mesenchymal stromal cells do not appear to transdifferentiate towards a hepatocyte-like phenotype using published protocols for other species. Canine iPSC are a promising candidate for an in-vitro source of hepatocyte-like cells.
73

Análise da expressão de MMP-2 e MMP-9 na pele de cães com Leishmaniose visceral /

Jacintho, Ana Paula Prudente. January 2012 (has links)
Orientador: Rosemeri de Oliveira Vasconcelos / Coorientador: Gisele Fabrino Machado / Banca: Daniel Cortes Beretta / Banca: Rosangela Zacarias Machado / Resumo: Os cães infectados pelo protozoário Leishmania (Leishmania) chagasi podem ou não apresentar sinais clínicos dessa zoonose e são a principal fonte de infecção para o homem. A pele é o primeiro órgão infectado pelo parasito na LVC. As enzimas metaloproteinases da matriz (MMPs) atuam na degradação da matriz extracelular (MEC) e na modulação da resposta inflamatória, frente a vários tipos de injúrias. O objetivo deste estudo foi avaliar a expressão de MMP-2 e MMP-9, por meio da técnica de imuno-histoquímica e zimografia na pele de cães naturalmente acometidos por LVC e comparar estes resultados com a imunodetecção das citocinas TNF- e TGF- e do protozoário Leishmania, com as possíveis alterações da matriz extracelular dermal. A alteração da composição de fibras colágenas da derme foi avaliada pela coloração PicroSirius. O método foi usado para diferenciar fibras colágenas dos tipos I e III, nas regiões do focinho, orelha e abdômen. A carga parasitária, intensidade de inflamação e a produção de MMP 2 e 9 foram maiores nas regiões cutâneas da orelha e focinho. Os macrófagos, linfócitos e plasmócitos predominaram no infiltrado inflamatório da derme superficial, formando granulomas, associados a degradação do colágeno maduro (tipo I) e a discreta deposição de colágeno jovem (tipo III), com maior intensidade nos cães com elevada carga parasitária cutânea. O TGF-β foi detectado nos três grupos de cães infectados (assintomático, oligossintomático e sintomático), sem diferenças significativas entre eles. O TNF-α não foi detectado na maioria dos animais infectados e no grupo controle. Conclui-se que quanto maior a carga parasitária e a intensidade de inflamação na pele, maior a degradação do colágeno maduro, produção de MMPs 2 e 9 e produção de TGF-β. A MMP-9 ativa poderia ser utilizada... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Dogs infected by Leishmania (Leishmania) chagasi may or may not show clinical signs of the zoonosis and they are the main source of infection for man. The skin is the first organ infected by the parasite in the LVC. The enzyme matrix metalloproteinases (MMPs) act on the degradation of extracellular matrix (ECM) and in the inflammatory response modulation against many kinds of injuries. The aim of this study was to evaluate the expression of MMP-2 and MMP-9 by immuno-histochemistry and zymography in the skin of dogs naturally affected by LVC and the immunodetection of TNF- and TGF- and of Leishmania and compare these results with the possible alterations of dermal extracellular matrix. The method was used to differentiate collagen fibers in the dermis was evaluated by Picrosirius red staining to differentiate collagen types I and III, in regions of the nose, ear and abdomen. The parasite load, intensity of inflammation, increased production of MMP 2 and 9 were higher in regions of the ear and muzzle. Macrophages, lymphocytes and plasma cells predominated in the inflammatory infiltrate of the superficial dermis, forming granulomas, associated with degradation of mature collagen (type I) and the discrete deposition of the young collagen (type III), with greater intensity in dogs with high parasite load skin. The TGF-β was detected in all groups of infected dogs (asymptomatic, oligosymptomatic and symptomatic), no significant differences among them. The TNF-α was not detected in most infected animals and the control group. It follows that the greater is the intensity of parasitic load and inflammation of the skin, the greater is the degradation of mature collagen, the production of MMPs and 2 and 9, production of TGF-β. Active MMP-9 could be used as a marker of inflammation in infected dogs. This profile of the... (Complete abstract click electronic access below) / Mestre
74

An Economic Analysis of Prairie Dog Control

Collins, Alan Robert 01 May 1981 (has links)
Prairie dog control was found to be economically feasible on the Conata basin in South Dakota with future annual maintenance control to prevent re-invasions. The large difference between the present net worth values of the two viewpoints ($2587 for the U.S. Forest Service acting as an agent of the sovereign and $109,011 for the ranchers ) was due to the added costs of environmental considerations included in the U.S. Forest Service control program, but assumed not to be included in control by ranchers. In order for prairie dog control to remain economically feasible, annual maintenance control for the U.S. Forest Service must be below 5 percent of the total initially controlled acreage in the control program (9 percent for the rancher viewpoint). Sun sedge (Carex heloiphila) constituted the major cattle forage increase from control in this study while western wheatgrass (Agropyron smithii), the dominant mid-grass in the area, showed no increase in production after five years of prairie dog elimination. Overall, 84 pounds per acre of usable cattle forage was gained from control.
75

"Kvinnan - hundens bästa vän" : Två experiment om empati

Angantyr, Malin January 2009 (has links)
<p>Två experiment undersökte empati och empatiträning. I Experiment 1 fick 130 deltagare läsa en berättelse där ett barn, en bebis eller en hundvalp for illa. Därefter skattade deltagarna sina känslor. Resultatet visade att kvinnor hade mer empati än män oavsett offer. Föräldrar hade mer empati än andra för barn/bebis. Hundägare hade mer empati än andra för hund. I Experiment 2, som gick vidare och undersökte empatiträning, deltog 38 elever i årskurs 3 och 4. Pojkar som fått empatiträning i form av REDE-projektet visade en tendens till mer empati än pojkar som inte använt projektet. Ingen effekt påvisades hos flickorna. Flickor verkar utveckla sin empati på egen hand medan pojkar verkar behöva lite hjälp.</p> / <p> </p><p>Two experiments investigated empathy and empathy training. In Experiment 1, 130 participants read a story where either a child, an infant or a puppy had been abused. The result showed that women had more empathy for all the victims than men. Parents had more empathy for a child/an infant than those who weren´t parents. Dog owners also showed more empathy for the puppy than those who didn´t own a dog. In Experiment 2, which consisted of 38 students in grades 3 and 4, boys who had used the REDE-project had a tendency to more empathy than boys who hadn´t used the project. No effect was demonstrated with the girls. Girls seem to develop their empathy on their own while boys seem to need some help.</p>
76

"Kvinnan - hundens bästa vän" : Två experiment om empati

Angantyr, Malin January 2009 (has links)
Två experiment undersökte empati och empatiträning. I Experiment 1 fick 130 deltagare läsa en berättelse där ett barn, en bebis eller en hundvalp for illa. Därefter skattade deltagarna sina känslor. Resultatet visade att kvinnor hade mer empati än män oavsett offer. Föräldrar hade mer empati än andra för barn/bebis. Hundägare hade mer empati än andra för hund. I Experiment 2, som gick vidare och undersökte empatiträning, deltog 38 elever i årskurs 3 och 4. Pojkar som fått empatiträning i form av REDE-projektet visade en tendens till mer empati än pojkar som inte använt projektet. Ingen effekt påvisades hos flickorna. Flickor verkar utveckla sin empati på egen hand medan pojkar verkar behöva lite hjälp. / Two experiments investigated empathy and empathy training. In Experiment 1, 130 participants read a story where either a child, an infant or a puppy had been abused. The result showed that women had more empathy for all the victims than men. Parents had more empathy for a child/an infant than those who weren´t parents. Dog owners also showed more empathy for the puppy than those who didn´t own a dog. In Experiment 2, which consisted of 38 students in grades 3 and 4, boys who had used the REDE-project had a tendency to more empathy than boys who hadn´t used the project. No effect was demonstrated with the girls. Girls seem to develop their empathy on their own while boys seem to need some help.
77

Problemhundar : En studie inriktad på hundar med grava aggressions- och rädsleproblem

Sundberg, Linn January 2011 (has links)
Dogs with behavioral problems This study was made to investigate if there was a problem in today’s society regarding dogs showing for example excessive aggression and/or anxiety. The main questions in this study was "is there a problem today" and "if there is a problem, what can we do to prevent it". To investigate these questions interviews were made with six different professions concerning the dog domain. The result of the study shows that three of the interviewed considered it to be a problem, one did not have an opinion on the matter and two choose not to call it a dog related problem because it mostly depends on the owner. Today about 20 – 25 % of the euthanasia’s in Denmark depends on aggressions or anxiety problems. It is the second most common reason for euthanasia. In Sweden 27 dogs were taken into custody during 2010, by the police in Stockholm, when they were considered dangerous to the society because of their aggression and anxiety problems. To prevent the problems from occurring we need to control the breeding more extensively and to be more careful selecting animals on which we choose to breed. Socialization is also an important factor to prevent aggression. Extensive socialization at an early age prevents aggressive behavior towards humans and also other animals. Anders Hallgren, a dog physiologist in Sweden estimates that about 75 % of the dogs that are sent to him for training can be well again.
78

Hunden-människans bästa arbetskamrat? : En kvalitativ studie om hundens inverkan på arbetsmiljön

Molin, Pernilla, Höglund, Sabina January 2012 (has links)
The study examines the meaning of having a dog in the workplace of personnel who work with therapy. The purpose was to examine the personnel’s view of dogs in their work envi-ronment. The study uses two theories. One is ‘psychosocial work environment’ and the other theory used is ‘symbolic interactionism’. The first theory aims to see the personnel in the con-text of their work environment. The second theory aims to examine the symbolic meaning of the dog for the personnel. The method used is a semi-structured qualitative interview with eight personnel that work in a place where they use therapy dogs as a part of therapy for the clients. The study showed that good work environment is very important to the personnel and that bad work environment affects them negatively both at work as well as at home. The study also showed that having a dog at a workplace has many advantages as cheering up the per-sonnel and clients, making the workload easier and makes the clients motivated for therapy. A negative aspect was that there are risks for allergic people and that the dog could be distract-ing to the clients.
79

none

Lin, Min-hun 09 October 2002 (has links)
none
80

A review and synthesis of dog cognition research : the world from a dog’s point of view

Bensky, Miles Kuiling 21 November 2013 (has links)
Driven by both applied and theoretical goals, scientific interest in canine cognition has experienced a rapid surge in popularity, especially over the last 15 years (Morell, 2009). Here we provide the most comprehensive review to date of dog cognition research, capturing all the articles (285) we could find on the subject going back to 1911. We begin by summarizing general research trends, first documenting the rapid recent growth in dog cognition research (particularly in the domain of social cognition), and then identifying a number of trends in terms of the cognition topics and dog populations studied. Next, we summarize and synthesize the substantive conclusions emerging from research on non-social (discrimination learning, object permanence, object learning, categorization, object manipulation, quantitative understanding, spatial cognition, memory) and social (responses to human cues, perspective taking, dog-human communication, social learning) cognition. In light of burgeoning research on individual differences in cognition and on the biological organization of cognitive domains, we highlight the potential impact of these topics on dog cognition. Finally, based on our syntheses, we outline some ideas for future research, including recommendations that studies focus on: (1) incorporating multiple sensory modalities (most notably olfaction); (2) using more diverse populations of subjects; (3) replicating studies where current knowledge is based on small study sets or on small samples; (4) identifying fundamental developmental patterns of cognitive development; (5) identifying individual differences in cognitive ability; and (6) identifying potential cognitive constraints (e.g., cognitive abilities that are non-independent due to pleiotropic biological organization). / text

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