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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.
41

Cryptocurrencies and Investor Disparities : A research paper about demographic factors’ effect on investment purpose and herd behavior among Swedish cryptocurrency investors

Lundström, Oscar, Pettersson Spångäng, Måns January 2022 (has links)
Cryptocurrencies have since the creation in 2008 constituted a unique and modern addition tothe financial setting throughout the world. Such assets are commonly known to be associatedwith great risk but also the possibility of great reward. The corresponding research field hasadapted to the evolution of cryptocurrencies and has for over a decade undergone a constantexpansion. Despite this, there is still plenty of unexplored territory within the particular researcharea and this report seeks to examine a part of it. The central topic of this paper concernscryptocurrencies in relation to Swedish retail investors’ different demographic factors and theeffect those have on investment strategy and behavior. To examine this, the report centersaround two main aspects, the investment purpose which cryptocurrency investors associatetheir investments with and investors’ exposure to herd behavior. Additionally, both aspectswere put in relation to various demographic factors to allow an analysis of whether demographicfactors affect the investors’ strategy and behavior. A quantitative method was used for theprocess of collecting data whereby a survey was constructed and replied to by Swedish retailinvestors active in the cryptocurrency market. The primary data obtained was analyzed andpresented through descriptive statistics, t-Tests, and regression models. By interpreting theresults, it was evident that demographic factors were found to not influence the investmentpurpose or the herd behavior of investors. This contradicts previous findings regardingtraditional markets e.g., the stock market where demographic factors are established as factorsaffecting both aspects. Hence, this report suggests that there are differences between thecryptocurrency market and traditional markets. Further, the research conducted in this paperindicates that a majority of investors associate cryptocurrency investments with speculativetrading and there is also a strong bias toward herd behavior among Swedish retail investorsactive in the cryptocurrency market.
42

Yellowstone's Northern Elk Herd: Critical Evaluation of the "Natural Regulation" Paradigm.

Kay, Charles Edward 01 May 1990 (has links)
Prior to 1968, the National Park Service contended that an unnaturally large population of elk had severely damaged Yellowstone Park's northern winter range, including aspen and willow communities. However, under "natural regulation" management adopted in the earl y 1970s the agency now believes that vegetation changes in the park are due to normal plant succession, climatic change, or fire suppression, not ungulates. The agency also believes that large numbers of elk (12, 000 - 15, 000) have wintered on the park's northern range for the last several thousand years. This study tested several of the major assumptions or predictions of the Park Service's "natural regulation" paradigm by collecting vegetational data, reviewing historical source materials, and analyzing archaeological reports. The available evidence suggests that observed changes in Yellowstone's tall willow and aspen communities are due primarily to ungulate browsing, not other factors. The future of sexually reproducing willow and aspen communities on the park's northern range appears to be in jeopardy. Under current management, their extinction is only a matter of time. Moreover, entire plant and animal communities have been affected, not just aspen and willows. Historical accounts and archaeological data indicate that few elk inhabited Yellowstone prior to creation of that national park in 1872. These results do not support the "natural regulation" paradigm. Prior to European influence, predation by Native Americans and carnivores limited elk, as well as other ungulate numbers throughout the Greater Yellowstone area.
43

A Management Study of the Cache Elk Herd

Hancock, Norman V. 01 May 1955 (has links)
American elk, by virtue of their distributio.n, were the most cosmopolitan members of the cervid family at the time of white settlement of North America. At this early date elk were present in every major region of what is now continental United States, as well as in northern Mexico. They likewise were abundant in upper and lower Canada, though records do not corroborate their presence too far north on the Atlantic coast. Although generally existent throughout the western states, elk were sparsely distributed in Nevada, southern Utah, and most of Arizona and New Mexico. Paucity of elk was also noted in eastern portions of Washington and Oregon.
44

Management, Foraging Behavior, Diet Composition and Forage Quality of Free-Ranging But Herded Camels in Ceeldheer District, Central Somalia

Elmi, Ahmed A. 01 May 1989 (has links)
In Somalia, camel (Camelus dromedarius) survivability and milk production has been higher than for other domestic livestock and contributes substantially to the subsistence of Somali pastoralists. The objective of this research was to study management, foraging behavior and nutrition of camels in their natural habitat to determine how production continues under seasonal nutritional stress. Management systems of Ceeldheer pastoralists are based on available natural pasture and water. The natural rotation grazing system maintained an ecological equilibrium in the District. Pastoralists manipulate their herds to suit existing environmental conditions, family needs and labor availability for herding. In herd management, control of breeding males and preferential treatment to increase the female component of the herd are geared to secure continuous milk supply for the family. Camels were watered only in the dry seasons. They foraged continuously throughout the day the first few days after watering, but foraged mostly in the morning and evening as watering days approached. The quantity of water camels consumed in summer and winter dry seasons were similar. In winter, milking camels foraged more, travelled shorter distance and rested less than dry ones. In fall, 1986, and spring, 1987, lactating camels spent less time foraging than non-milking animals. Foraging time was the same for both groups in summer 1986, 1987 and fall, 1987. Camels spent more time chewing bones in summer of 1986 in Xarar foraging area than other seasons. Low or high relative humidity together with hot temperature apparently reduced foraging time, increased rumination and idling times in winter and spring seasons. As forage availability declined, camels ingested a broader array of dietary items in the dry seasons and consumed large amounts of herbaceous plants. The diets of milking and dry camels were similar. Lactating camels consumed more green forage than dry camels in the dry seasons. Shrubs and trees comprised major components of the diets (80.9%). Physical structures of plant species did not prevent feeding on the plants. Camel diets were rich in crude protein (cp), calcium (Ca), potassiuim and sodium. Phosphorus (P) was deficient. Ca:P ratios were extremely low. Neutral detergent fiber and acid detergent lignin were high. CP intake seemed adequate year round assuming camel protein requirements are similar to other livestock requirements. Digestible energy was deficient in dry seasons. Low energy intake, inadequate phosphorous availability and water deprivation were probably responsible for the weight loss of camels as the dry season progressed.
45

Assessing the microbiological profile of raw goat milk and understanding producer practices and perceptions

Leopard, Jacinda Skye 13 May 2022 (has links)
Raw milk sales are legal in 30 states, including Mississippi, where regulations are largely management-based and not food-safety related. The research objectives were to analyze the microbial profile of raw goat milk from Mississippi farms and assess food safety practices and perceptions of dairy goat farmers. Deficiencies and opportunities for improvement in raw goat milk safety were identified. Staphylococcus spp. was present in most (70%) milk samples but aligned with drying-off. E. coli, Enterobacteriaceae, and coliforms were observed in 4, 10, and 12 samples, respectively; no Salmonella spp. or Listeria monocytogenes were detected. The survey highlighted farmers' need for educational opportunities on safe milk handling with emphasis on handwashing. Most producers (80.8%) are willing to invest more in their farms, creating strategic opportunities for extension outreach to help with market expansion and sustainability. Overall, training accessibility could help producers nationwide by encouraging safe milk handling and best management practices.
46

Two Layers of Selfish-Herds in Spawning Aggregations of Chub (Nocomis Sp.) and its Nest Associates

Betts, Madison 18 August 2023 (has links)
Many species have evolved to live in groups. Gregarious behavior was believed to be adaptive for whole-population survival and predator evasion until selfish-herd theory was introduced. It proposed that individuals congregate not as a method of protection for the entire population, but instead to better the individual's chance of survival, thereby using the group to benefit itself (i.e., "selfishness"). Selfish behavior is a common part of mutualisms, which are complex, dynamic interactions that often change with biotic or abiotic circumstance. Here, I investigate potential selfish behavior within the mixed-species spawning aggregations hosted by bluehead chub (Nocomis leptocephalus). I hypothesized that the host benefits more directly from the aggregation it supports than previous research suggests – specifically, by using nest associates to decrease its own risk of predation (creating a selfish-herd) and simultaneously forcing associate embryos into marginal nest locations while locating its own embryo in the safer locations within the nest (creating an "embryonic selfish-herd"). In Chapter 1, I investigated the adult spawning aggregation for possible selfishness by monitoring the chub's spatial location within the aggregation and vigilance behavior under varying associate abundances. I found that the host occupied the central location within the aggregation and was less vigilant when associate abundance was high. In Chapter 2, I examined the "embryonic herd" contained within Nocomis nests for possible embryonic selfishness orchestrated by the chub host, leading to increased embryonic survival for chub young and elevated fitness for chub parents. I found that deeper nest sections support higher embryonic survival than shallower sections, and that chub embryo make up a disproportionate percentage of embryos found in those deeper sections. I also conducted a preliminary study investigating embryo-predation by host on associate embryo which produced evidence for embryo-predation by both host and two associates on each other's offspring. Cohesively, my results support the identification of the host as a selfish participant and confirm the presence of both an adult and embryonic selfish-herd in this mutualism. This is the first study to demonstrate selfish behavior on the part of the host in this system and the first to prove the existence of an embryonic selfish-herd. / Master of Science / A fish has three goals: to survive, to grow, and to reproduce. Mutualisms – when all participants experience a net benefit from interacting – arise when two or more species rely on each other to meet these objectives. In many mutualisms, however, not all participants benefit equally. Selfish-herd theory identifies those that maximize their own benefit while minimizing or negating any cost as "selfish" individuals. I examined the mutualistic mixed-species spawning aggregations hosted by a freshwater minnow, bluehead chub (Nocomis leptocephalus), for possible selfish behavior. I found that bluehead chubs disproportionately benefit from the aggregations they host and use the aggregation to improve their own survival, improve their offspring's survival, and obtain food (by eating others' offspring). Thus, I identify bluehead chub as a selfish participant and provide evidence for the existence of two selfish herds in this mutualism – one among the adult fishes and one among their young – both orchestrated by and benefiting the bluehead chub. This study is the first to identify the bluehead chub as such and rewrites our previous understanding of this mutualism, which largely denied bluehead chub as a direct beneficiary. This work contributes to the global discussion of mutualisms by attesting the complexity of these relationships and offers support for re-examination of the classification of many known interspecific interactions, such as those cursorily termed nest parasitisms.
47

Comparisons of Holstein, Brown Swiss, and Jersey cows for age at first calving, first calving interval, and true herd-life up to five years in seven regions of the United States

Garcia-Peniche, Teresa Beatriz 11 January 2005 (has links)
The objectives of this research were to evaluate breed differences for heat-stress resistance using age at first calving and first calving interval, and to assess breed by region interactions for seven regions of the United States for survival-related traits up to five years of age in Brown Swiss, Holstein, and Jersey cows. Age at first calving and first calving interval were studied in farms with two breeds, with Holstein and Brown Swiss or Holstein and Jersey cows. The survival-related traits were analyzed in farms with one or two breeds. Seven regions within the United States were defined: Northeast, Northwest, Central north, Central, Central south, Southwest and Southeast. The fertility traits were also analyzed in seven individual states: Wisconsin, Ohio, Oregon, California, Arizona, Florida, and Texas. Brown Swiss were older than Holsteins at first calving (833 ± 2.4 d vs. 806 ± 2.0 d in regions, and 830 ± 3.1 d vs. 803 ± 2.4 d in states), but Holsteins and Brown Swiss did not differ for first calving interval. Jerseys were younger than Holsteins at first calving and had shorter first calving intervals (P < 0.01). In data from individual states, Holsteins housed with Brown Swiss were older at first calving than Holsteins housed with Jerseys (800 ± 2.7 d vs. 780 ± 2.5 d). Holsteins housed with Jerseys had slightly shorter first calving intervals than Holsteins housed with Brown Swiss, and the interaction of "type of Holstein: with season of the first calving was highly significant (P < 0.01). Region and season effects were smaller for Jerseys than for Holsteins, thus, Jerseys showed evidence of heat-stress resistance with respect to Holsteins. Management modified age at first calving in Holsteins, depending on the type of herd they were located in. Longer calving intervals might have been partly due to voluntary waiting period to breed the cows. The survival-related traits were evaluated up to five years of age. They consisted of stayability, number of completed lactations, days lived, herd-life, and total days in milk. For herds with one breed, the order for stayability to five years of age, from longer to shorter-lived breed was: Brown Swiss, Jersey and Holstein, but for the ratio of days in milk to herd-life the order was: Holstein, Jersey and Brown Swiss, and for the ratio of days in milk to days lived, it was: Jersey, and Holstein and Brown Swiss tied. This last ordering was the same for number of lactations completed by five years of age. The results for two-breed herds were similar since Brown Swiss and Jerseys had larger (Chi-square P < 0.01) probabilities of living past five years of age than Holsteins, and for days in milk and number of lactations completed, Jerseys had higher values than Holsteins (P < 0.01), but Holsteins and Brown Swiss tied in some analyses. Breed by region interaction was always significant. If all other conditions were assumed equal, Jerseys would give fastest returns by five years of age. The overall conclusion is that Jerseys performed better for the traits analyzed, all of them highly influenced by environmental conditions. / Ph. D.
48

Cheating and Selfishness in Reproductive Interactions among Nest Associative Cyprinids

Floyd Jr, Stephen Preston 13 June 2016 (has links)
Mutualism is an understudied interaction in ecosystems throughout the world. Within the eastern United States, one fish-fish mutualism is the nest association between Nocomis and other cyprinids. I assessed the role of host parental care while testing for the selfish-herd effect. Additionally, I examined multiple nest associates in order to elucidate potential cheaters. I utilized gonadosomatic index (GSI) to compare reproductive condition among the bluehead chub Nocomis leptocephalus and its putative nest associates in Catawba Creek, Virginia. GSI of potentially obligate associates tracked host GSI more closely than weak associates, while weak associates spawned prior to Nocomis spawning. Given their GSI patterns and behavior, central stonerollers Campostoma anomalum may be cheaters in the interaction. I used multiple experiments to test for the selfish-herd effect, the role of parental care, and how relative risk influences reproductive decisions of associates. Most eggs were located in the bottom upstream quarter of nests, and a molecular analysis revealed that stonerollers and chubs constituted the majority of identified individuals. A comparison of host-associate ratios from four nest sections failed to identify the selfish herd effect. Another experiment found that host egg covering significantly reduced egg predation. Lastly, I assessed relative egg predation risk at four potential spawning locations; predation levels did not differ significantly at any location. While GSI patterns suggest that stonerollers may be cheaters, genetic evidence indicates that stonerollers spawn on Nocomis nests. Because GSI does not completely assess reproduction, secondary stoneroller reproduction on Nocomis nests may have been overlooked. / Master of Science
49

Utilisation des données de contrôles élémentaires pour la modélisation et l'estimation des interactions génotype x milieu : Etude en bovins laitiers / *

Huquet, Bérénice 08 October 2012 (has links)
La France présente une grande diversité de conditions pédoclimatiques et par conséquent des systèmes d'élevage très variés. Pourtant, les schémas de sélection actuels en bovins laitiers considèrent que les meilleurs reproducteurs sont les mêmes quel que soit le type de système d'élevage, c'est-à-dire qu'il n'existe pas d'interactions Génotype*Milieu. L'objectif de cette thèse est de mesurer les interactions Génotype*Milieu en France sur les caractères laitiers et fonctionnels dans les 3 races bovines laitières principales (Normande, Montbéliarde, Holstein).Un point crucial dans ce type d'étude est la façon de définir le milieu. L'innovation de cette thèse est l'utilisation des profils Troupeau-Jour de Contrôle. Ce sont des coproduits du modèle génétique basé sur les contrôles élémentaires. Ils reflètent la production permise par la conduite de troupeau au cours du temps. Ils présentent l'avantage d'être disponibles à partir des bases de données nationales et d'être uniquement le reflet de la conduite, contrairement à d'autres définitions qui mêlent effet génétique et effet d'environnement au sein de la définition du milieu ou qui se focalisent sur certains points précis de la conduite sans prendre en compte son effet global. La description des profils Troupeau-Jour de Contrôle de plus de 15000 élevages normands, montbéliards et holsteins par des méthodes de lissage de séries temporelles, d'analyses factorielles et de classification a permis de créer 2 définitions du milieu en vue de l'étude des interactions Génotype*Milieu : des milieux définis comme des groupes d'élevages aux conduites distinctes ou un milieu défini comme un continuum à travers une ou des variables synthétiques.L'importance des interactions Génotype*Milieu a été estimées à partir de 2 types de modèles : un modèle multicaractères qui valorise la définition du milieu sous forme de groupes d'élevages et un modèle de norme de réaction qui valorise, quant à lui, le milieu défini comme un continuum. Les avancées méthodologiques proposées dans cette thèse concernent les modèles de normes de réaction. Des approches permettant de prendre en compte plusieurs variables d'environnement au sein d'un même modèle et de les résumer au sein d'une matrice génétique de rang réduit sont mises en avant.Aucun reclassement n'a été mis en évidence : les meilleurs reproducteurs sont les mêmes quel que soit le système d'élevage. Les schémas des sélections actuels sont donc performants. Il existe tout de même une interaction Génotype*Milieu significative sous forme d'effet d'échelle : la variabilité des valeurs génétiques des animaux est plus importante dans les systèmes d'élevage plus intensifs. Cet effet d'échelle ne sera pas pris en compte dans les modèles d'évaluation génétique, en revanche, il est possible d'imaginer un indicateur utilisable sur le terrain pour mesurer les écarts de performances, dus à cet effet, auxquels il faut s'attendre. / Because of the diversity of pedoclimatic conditions in France, dairy farms have very diversified herd management systems. For this reason, some breeders question the efficiency of the existing breeding schemes for their own management system. To overcome these concerns, a genotype by environment interaction study at the French national level has been considered necessary. The aim of this thesis is to assess the presence of genotype by environment interactions in Normande, Montbéliarde and Holstein breeds for production and functional traits.A tricky point in genotype by environment interaction studies is the environmentdefinition. The innovation of this thesis deals with the use of Herd-Test Day profiles.They are co-products of the French test day model. They reflect the production dueto herd management over time. They are available in national databases and only reflect herd management effect contrary to other definitions in which there is a confusion between genetic and environmental effects in the environment definition or which focus on specific features of the herd management without taking into account its global effect. Herd Test Day profiles of more than 15,000 herds have been studied through time series smoothing, factor analysis and clustering methods. It led to 2 definitions of the environment for the genotype by environment interaction study : environments defined as herd groups or one to several environmental gradients.Genotype by environment interactions were assessed with 2 models : the multitrait model and the reaction norm model. The first one uses herd groups as definition of the environment whereas reaction norm model considers the environment as a gradient. Several methodological improvements have been suggested for reaction norm models : taking into account several environmental gradients in a reaction norm model and summarizing them through a reduced rank genetic matrix.No reranking has been shown : the best parents are the same whatever the herd management system. Consequently, current breeding schemes are relevant. However, a scale effect exists : the variability of animal breeding values is higher in intensive herds. Genetic models will not account for this scale effect. However, a tool useful for breeders could indicate the deviation between expected performances and actual performances due to this scale effect.
50

Energy-saving biomass stove / Bếp tiết kiệm năng lượng dùng nguyên lý khí hóa trấu

Hoang, Tri 09 December 2015 (has links) (PDF)
This paper introduces an energy-saving biomass stove. The principle of energy-saving biomass stove is gasification. It is a chemical process, transforms solid fuel into a gas mixture, called (CO + H2 + CH4) gas. Emission lines in the stove chimneys typically remain high temperatures around 900 to 1200C. The composition of the flue gas consists of combustion products of rice husk which are mainly CO2, CO, N2. A little volatile in the rice husk, which could not burn completely, residual oxygen and dust will fly in airflow. The amount of dust in the outlet gas is a combination of unburnt amount of impurity and firewood, usually occupied impurity rate of 1 % by weight of dry husk. Outlet dust of rice husk furnace has a normal size from 500μm to 0.1 micron and a particle concentration ranges from 200-500 mg/m3. Gas emissions is created when using energy-saving stove and they will be used as the main raw material in combustion process Therefore the CO2 emission into the environment when using the stove will be reduced up to 95% of a commonly used stove. / Bài báo giới thiệu một bếp tiết kiệm dùng năng lượng sinh khối. Bếp tiết kiệm năng lượng thực hiện nguyên lý khí hóa sinh khối. Đó là một quá trình hóa học, chuyển hóa các loại nhiên liệu dạng rắn thành một dạng hỗn hợp khí đốt, gọi là khí Gas (CO + H2 + CH4). Dòng khí thải ra ở ống khói của bếp thông thường có nhiệt độ vẫn còn cao khoảng 900 ~ 1200C. Thành phần của khói thải bao gồm các sản phẩm cháy của trấu, chủ yếu là các khí CO2, CO, N2, một ít các chất bốc trong trấu không kịp cháy hết, oxy dư và tro bụi bay theo dòng khí. Lượng bụi tro có trong khói thải chính là một phần của lượng không cháy hết và lượng tạp chất không cháy có trong củi, lượng tạp chất này thường chiếm tỷ lệ 1% trọng lượng trấu khô.Bụi trong khói thải lò đốt trấu thông thường có kích thước hạt từ 500μm tới 0,1μm, nồng độ dao động trong khoảng từ 200-500 mg/m3. Lượng khí thải được sinh ra khi sử dụng bếp tiết kiệm năng lượng, sẽ được dùng làm nguyên liệu đốt cháy chính của quá trình đó. Do đó lượng khí CO2 thải ra môi trường khi sử dụng bếp tiết kiệm sẽ được giảm xuống 95 % so với sử dụng bếp thường.

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