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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.
91

Rye and vetch intercrops for reducing corn in fertilizer requirements and providing ground cover in the Mid-Atlantic region

Sullivan, Preston 13 October 2005 (has links)
Winter-annual cover crops reduce soil erosion by providing ground cover, while producing energy-cheap N for a subsequent crop. Incorporated cover crops or those left as no-till mulch can enhance soil structure and water infiltration. A series of studies was designed to test agronomic advantages of growing mixtures of rye plus hairy vetch and hairy plus bigflower vetches. Plots were arranged in randomized complete blocks and the study conducted for two consecutive cover crop/corn sequences. I measured N yield of cover crops, their ground-covering ability, and their influence on soil structure and a subsequent corn crop. Nitrogen yields ranged from 53 to 187 kg/ha using either pure stands of hairy vetch or mixtures of hairy vetch plus bigflower vetch. Nitrogen yields for rye plus hairy vetch mixtures ranged from 90 to 179 kg/ha. Rye growing in association with vetch had lower C:N ratios (47:1) than pure rye (59:1), apparently deriving additional N from vetch. Vetches were poor at covering the ground in the fall (< 15% cover) as compared to rye (> 41% cover) or mixtures of rye and vetch (25 to 45% cover). When compared to vetch pure stands, corn yields were suppressed 5 to 42% by including rye with vetch due to N immobilization from the rye component and reduced N yield from the vetch component. Corn yields from hairy vetch or hairy: bigflower vetch mixtures were 15.5 Mg/ha and 16.2 Mg/ha respectively and statistically similar to rye + 140 kg N/ha (16.7 Mg/ha). Corn following the two-vetch mixture took up 129 kg N/ha, while corn following hairy vetch took up 114 kg N/ha. Using N fertilizer, corn N uptake was 183 kg N/ha following 140 kg N/ha fertilizer and 213 kg/ha following 210 kg/ha N fertilizer. Increased soil moisture seemed to be related to the presence of a surface mulch. I was unable to detect any changes in water-stable soil aggregates in the upper 15 cm after 2 years of cover cropping. During 1988, water infiltration in no-till plots was lower than in plots that had been disk incorporated, but a tillage effect was not seen in 1989. / Ph. D.
92

Processo alternativo de catch-up em indústrias intensivas em recursos naturais: uma análise empírica da trajetória tecnológica da indústria de bioetanol de cana-de-açúcar no Brasil

Gonzalez, Rafael Kuramoto January 2016 (has links)
Submitted by Rafael Kuramoto Gonzalez (rafael_k_gonzalez@yahoo.com.br) on 2016-03-23T14:48:48Z No. of bitstreams: 1 Tese_Final_Rafael_Kuramoto_Gonzalez.pdf: 7373873 bytes, checksum: 4e120ff57a6ae6198920ff7722bd7d8f (MD5) / Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2016-03-23T18:45:26Z (GMT) No. of bitstreams: 1 Tese_Final_Rafael_Kuramoto_Gonzalez.pdf: 7373873 bytes, checksum: 4e120ff57a6ae6198920ff7722bd7d8f (MD5) / Approved for entry into archive by Maria Almeida (maria.socorro@fgv.br) on 2016-03-30T14:42:35Z (GMT) No. of bitstreams: 1 Tese_Final_Rafael_Kuramoto_Gonzalez.pdf: 7373873 bytes, checksum: 4e120ff57a6ae6198920ff7722bd7d8f (MD5) / Made available in DSpace on 2016-03-30T14:42:51Z (GMT). No. of bitstreams: 1 Tese_Final_Rafael_Kuramoto_Gonzalez.pdf: 7373873 bytes, checksum: 4e120ff57a6ae6198920ff7722bd7d8f (MD5) Previous issue date: 2015 / This thesis concerns about the technological development and innovation in natural resources’ intensive industries in the context of emerging economies. The thesis explores how the accumulation of technological capabilities and the learning mechanisms influenced the technological trajectory in the sugarcane bioethanol industry in Brazil, during the period from mid-1970 to 2014. Much progress has been made in understanding the technological catch-up process of firms and industries in emerging economies. However, these studies often explore the process of technological catch-up related to technological trajectories already mapped by world leaders in manufacturing and processing industries. Part of this studies ignore that the development of industrial activities could occur in natural resources’ intensive industries. In addition, between academic researchers and policy makers, natural resources’ intensive industries are encapsulated as commodities and low-tech, characterized by a limited opportunity for technological learning and accumulation of technological capabilities. However, the process of industrialization in natural resources’ intensive industries in regions such as Latin America is poorly understood and there are scarce research investigating the process of technological catch-up systematically in industrial level, with rare exceptions. Based on evidence from sugarcane bioethanol industry in Brazil, this research explores a process of technological catch-up that has received little attention in the literature. To examine this issue, this research adopts a qualitative design based on a case study strategy at industry level, with extensive fieldwork and collection of firsthand empirical evidence with long-term coverage on 20 organizations. This research found that: (1) The technological trajectory’s evolution of sugarcane bioethanol industry in Brazil was characterized by the opening of a different direction from that mapped by existing technology leaders. This qualitative shift process of the dominant technological trajectory started during the early stages of technology development. So, the industry went through a trajectory of early entry in path-creating; (2) The evolution of this technological trajectory did not happen in a homogeneous way. Were found three relatively distinct patterns of accumulation of technological capabilities for specific technological functions (or areas): feedstock, agricultural processes and industrial processes. In feedstock and industrial processes technological functions there an accumulation of technological capabilities of global leadership, while in the agricultural processes technological function the accumulation of technological capabilities has not evolved beyond the intermediate level; (3) These capabilities were accumulated in a disperse way among industry’s actors (producer firms, research institutes, universities, suppliers, biotechnology companies and etc.) and made possible the opening of exploration of new businesses, albeit modestly exploited; (4) The subtle heterogeneity found in the patterns of technological capabilities accumulation was influenced by a combination of technological learning processes used by the industry over time. Finally, the research also found that this technological trajectory contributed to generate significant implications and was also influenced by other factors. Nevertheless, these results deserve more systematic research effort. Therefore, this research concludes that relevant technological positions, especially for industries from emerging economies, can be achieved through technological trajectories that are not based necessarily on dominant technologies, already exploited by world leaders in advanced economies. Thus, alternative processes of catch-up may be highly relevant for obtaining industrial progress. Furthermore, the research concludes that natural resources’ intensive industries offer opportunities for significant innovations and can be protagonists in this alternative catch-up process, particularly in the context of countries with abundance of natural resources. Therefore, this research contributes to generate new evidence and explanations that help us expand the notion of alternatives to the industrial and economic development in the context of emerging economies. In the debate on industrial and economic development, alternative technological trajectories, as well as intensive industries in natural resources, should receive special attention by public policy makers and business actions. / Esta tese diz respeito ao desenvolvimento tecnológico e inovação em indústrias intensivas em recursos naturais no contexto de economias emergentes. A tese explora como a acumulação de capacidades tecnológicas e os mecanismos de aprendizagem influenciaram a trajetória tecnológica na indústria de bioetanol de cana-de-açúcar no Brasil, durante o período de meados da década de 1970 a 2014. Muito se avançou na compreensão do processo de catch-up tecnológico de empresas e indústrias de economias emergentes. Contudo, essas pesquisas geralmente exploram o processo de catch-up tecnológico relacionado às trajetórias tecnológicas já mapeadas pelos líderes mundiais em indústrias de manufatura e transformação. Parte desses estudos ignora que o desenvolvimento de atividades industriais poderia ocorrer em indústrias intensivas em recursos naturais. Além disso, indústrias intensivas em recursos naturais são geralmente encapsuladas como commodities e low-tech, caracterizadas por uma limitada oportunidade de aprendizagem tecnológica e acumulação de capacidades tecnológicas. Entretanto, o processo de industrialização em indústrias intensivas em recursos naturais em regiões como a América Latina ainda é pouco compreendido e são escassas as pesquisas que investigam o processo de catch-up tecnológico em nível de indústria, com raras exceções. Baseando-se em evidências da indústria de bioetanol do Brasil, esta pesquisa explora um processo de catch-up tecnológico que tem recebido pouca atenção na literatura. Esta pesquisa adotou um desenho qualitativo com base em uma estratégia de estudo de caso em nível de indústria, com extensivo trabalho de campo e coleta de evidências empíricas de primeira mão com cobertura de longo prazo em 20 organizações. Esta pesquisa encontrou que: (1) a evolução da trajetória tecnológica da indústria de bioetanol no Brasil caracterizou-se pela abertura de uma direção distinta daquela mapeada por líderes tecnológicos existentes. Esse processo de desvio qualitativo da trajetória tecnológica dominante iniciou durante os primeiros estágios de desenvolvimento tecnológico. Assim, a indústria percorreu uma trajetória de entrada precoce em path-creating; (2) a evolução dessa trajetória tecnológica não se deu de maneira homogenia. Foram encontrados três padrões relativamente distintos de acumulação de capacidades tecnológicas para funções (ou áreas) tecnológicas específicas: feedstock, processos agrícolas e processos industriais. Nas funções de feedstock e processos industriais, houve acumulação de capacidades tecnológicas de liderança mundial, enquanto na função processos agrícolas a acumulação de capacidades tecnológicas não evoluiu além do nível intermediário; (3) essas capacidades foram acumuladas de forma dispersa entre os atores da indústria (empresas produtoras, institutos de pesquisa, universidades, fornecedores, empresas de biotecnologia etc.) e possibilitaram a abertura de oportunidades de exploração de novos negócios, ainda que modestamente aproveitadas; e (4) a sutil heterogeneidade encontrada nos padrões de acumulação de capacidades tecnológicas foi influenciada pela combinação de mecanismos de aprendizagem tecnológica utilizados pela indústria ao longo do tempo. Por fim, constatou-se também que essa trajetória tecnológica contribuiu para gerar implicações significativas e foi também influenciada por fatores outros. Não obstante, esses resultados merecem esforço de investigação mais sistemático, uma vez que foram examinados aqui de forma superficial. Concluiu-se, portanto, que posições tecnológicas relevantes, especialmente por indústrias de economias emergentes, podem ser alcançadas por meio de trajetórias tecnológicas que não se baseiam, necessariamente, em tecnologias dominantes, já exploradas por líderes mundiais, de economias avançadas. Assim, os processos alternativos de catch-up podem ser altamente relevantes para a obtenção de progresso industrial. Ademais, a pesquisa concluiu que as indústrias intensivas em recursos naturais oferecem oportunidades para inovações significativas, e podem ser protagonistas nesse processo de catch-up alternativo, particularmente no contexto de países abundantes em recursos naturais. Assim sendo, esta pesquisa contribui para gerar novas evidências e explicações que nos ajudem a ampliar a noção de alternativas para o desenvolvimento industrial e econômico no contexto de economias emergentes. No debate sobre desenvolvimento industrial e econômico, as trajetórias tecnológicas alternativas, bem como as indústrias intensivas em recursos naturais, deveriam receber uma atenção especial por parte de decisores de políticas públicas e de ações empresariais.
93

Influence of vaccination dose and catch-up campaign on antibody titers against measles and rubella among university students / 大学生における麻疹および風疹のウイルス抗体価に対するワクチン接種回数およびワクチン追加接種キャンペーンの影響

Takeuchi, Jiro 24 March 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18173号 / 医博第3893号 / 新制||医||1003(附属図書館) / 31031 / 京都大学大学院医学研究科医学専攻 / (主査)教授 中山 健夫, 教授 木原 正博, 教授 一山 智 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM
94

När bok blir film… : En jämförande analys av boken och filmen Catch me if you can

Juniku, Majlinda January 2008 (has links)
<p>Abstract</p><p>Title: When book becomes film... – a comparative analysis of the book and film Catch me if you can (När bok blir till film…En jämförande analys av boken och filmen Catch me if you can)</p><p>Number of pages: 46</p><p>Author: Majlinda Juniku</p><p>Tutor: Amelie Hössjer</p><p>Course: Media and Communication Studies C</p><p>Period: Autumn term 2007</p><p>University: Division of Media and Communication, Department of Information Science, Uppsala University.</p><p>Purpose/Aim: To study what model of dramaturgy belongs to the film Catch me if you can and to see what has been crossed out, altered and added from the book so the narrative will fit this model.</p><p>Material/Method: The film Catch me if you can and the book with the same name has been used to analyze the differences between them. I have divided the differences into three categories: Crossed out, Altered and Added. In the analysis section these have been presented in each section of the film.</p><p>Main results: Catch me if you can is definetly a film made with the design of the Anglosaxon model, mostly because of its timestructure and that it portrays an action and not just a condition which is normal in the epic-lyric model. Big parts of the story have been crossed out, altered and added to make the film more acceptabel to the audience. Most of the changeshad been done to make the story shorter to fit the timeframe of a film. Events had been joinedtogether to save time but not miss anything. A character, Hanratty, has been reinforced to create a cat-and-mouse story and add excitement to the film. Other changes have been made to make the main character seem more likeable to the audience.</p><p>Keywords: book, film, dramaturgy, Catch me if you can, anglo-saxon, epic-lyric</p>
95

Agroecosystem Optimization by Crop Rotation, Catch Crop and Manure in Organic Farming / Agroekosistemų optimizavimas augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje

Balnytė, Skirmantė 02 September 2011 (has links)
To analyse the influence of crop rotations with a different ratio of nitrogen-fixing crops, catch crops and fertilisation with organic fertilisers on the following: 1. Soil enzyme activity; 2. Agrochemical properties of the soil and nitrogen balance; 3. Weed response; 4. Weed seed bank in the soil; 5. Crop yield and productivity. / Agroekosistemų optimizavimo augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje tyrimai vykdyti 2004–2009 m., Lietuvos žemės ūkio universiteto Bandymų stotyje, sertifikuotame ekologinės žemdirbystės lauke, karbonatingame sekliai glėjiškame išplautžemyje (IDg8-k) – Calcari-Epihypogleyic Luvisol (LVg-p-w-cc). Tyrimų hipotezė. Optimizuoti agroekosistemas ekologinėje žemdirbystėje galima taikant priemonių kompleksą: parenkant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius bei tręšiant organinėmis trąšomis. Tyrimų tikslas – įvertinti agroekosistemų optimizavimo galimybes ekologinėje žemdirbystėje derinant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius ir tręšiant organinėmis trąšomis. Tyrimų uždaviniai: Ištirti sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių ir tręšimo organinėmis trąšomis įtaką: 1. dirvožemio fermentų aktyvumui; 2. dirvožemio agrocheminėms savybėms ir azoto balansui; 3. pasėlių piktžolėtumui; 4. dirvožemio armens užteršimui piktžolių sėklomis; 5. augalų derlingumui ir bendrosios energijos kiekiui. Mokslinio darbo naujumas. Ekologinės žemdirbystės sąlygomis kompleksiškai įvertintas sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių bei tręšimo organinėmis trąšomis poveikis agroekosistemoms. Tai suteikia naujų žinių apie potencialaus dirvožemio derlingumo palaikymo, pasėlių ir dirvos piktžolėtumo kontrolės... [toliau žr. visą tekstą]
96

Sėjomainų ir tarpinių pasėlių įtaka dirvos piktžolėtumui ir fermentų aktyvumui ekologinėje žemdirbystėje / The influence of crop rotations and catch crops on weed seed-bank and soil enzymes activity in the organic farming

Jasionė, Vaidutė 03 June 2011 (has links)
Tyrimai atlikti 2008–2009 m. Lietuvos žemės ūkio universiteto Bandymų stotyje. Dirvožemis – karbonatingas sekliai glėjiškas išplautžemis (Calc(ar)i-Epihypogleyic Luvisol). Tyrimo A veiksnys – 4 septynių narių sėjomainų rotacijos su nevienoda azotą fiksuojančių augalų dalimi: I – 43 proc. (daugiametės žolės → daugiametės žolės → žieminiai kviečiai → vasariniai miežiai → žirniai → žieminiai kviečiai → miežiai), II – 43 proc. (daugiametės žolės → žieminiai kviečiai → žirniai → vasariniai miežiai su įsėliu → daugiametės žolės → žieminiai kviečiai → miežiai), III – 29 proc. (daugiametės žolės → bulvės → belukštės avižos → vasariniai miežiai → žirniai → žieminiai kviečiai → miežiai), IV – 14 proc. (daugiametės žolės → žieminiai kviečiai → bulvės → vasariniai miežiai → žieminiai rapsai → žieminiai kviečiai → miežiai). Veiksnys B – tarpinis pasėlis žaliajai trąšai: 1) be tarpinio pasėlio, 2) tarpinis pasėlis žaliajai trąšai. Nustatyta, kad sėjomainos piktžolių sėklų atsargoms dirvoje esminės įtakos neturėjo. Tarpinis pasėlis žaliajai trąšai, lyginant su jo nenaudojimu, turėjo tendenciją mažinti nuo 5,4 iki 44,2 proc. piktžolių sėklų atsargas dirvoje. Piktžolės pasiskirstė į 4 ekologines grupes pagal poreikį dirvožemio pH, azotui ir drėgnumui. Didžiausias sėklų kiekis dirvoje nustatytas indiferentiškų pagal poreikį dirvožemio pH ir drėgnumui, mažo rūgštumo ir silpnai šarminių dirvožemių piktžolių rūšių, azoto turtinguose dirvožemiuose augančių dažniau negu neturtinguose bei... [toliau žr. visą tekstą] / Field experiments were carried out in 2008 and 2009 at the Experimental Station of Lithuanian University of Agriculture. The objective of this investigation was to determine the influence of crop rotations and catch crops for green manure on weed seed-bank and soil enzymes urease and saccharase activity in the organic farming. Soil – Calc(ar)i-Epihypogleyic Luvisol. Factor A of the experiment – crop rotations with a different ratio of nitrogen fixing crops: I – 43% (grass-clover→grass-clover→winter wheat→spring barley→peas→winter wheat→spring barley), II – 43% (grass-clover→winter wheat→peas→spring barley→grass-clover→winter wheat→spring barley), III – 29% (grass-clover→potato→oat→spring barley→peas→winter wheat→spring barley), IV – 14% (grass-clover→winter wheat→potato→spring barley→winter rape→winter wheat→spring barley). Factor B – catch crop: 1) without catch crop, 2) with catch crop. Crop rotations had no significant effect on weed seed-bank. Catch crop for green manure, compared to without catch crop, decreased from 5.4 to 44.2% the amount of weed seeds. Weeds distributed into 4 ecological groups according to soil pH, nitrogen and soil moisture demand. The highest amount of weed seeds belonged to indifferent to soil pH and moisture, slightly acid and slightly alkaline soil, more frequent on nitrogen rich soil than on poor and moderately nitrogen rich soil and very nitrogen rich soil, dry and moderately moist soil weed species. Qualitative distribution of weeds into... [to full text]
97

Mitybos įtaka žiurkių palikuonių fizinei būklei / The influence of maternal nutrition on physical status in rat offspring

Araminaitė, Violeta 27 June 2014 (has links)
Nepakankama mityba iki nėštumo ir per nėštumą gali lemti palikuonio svorio pokyčius, vėlesnę brandą ar lėtines neinfekcines ligas suaugus. Darbo tikslas: Įvertinti mitybos iki nėštumo ir per nėštumą įtaką žiurkių palikuonių fizinei būklei. Uždaviniai: 1. Nustatyti ir palyginti žiurkių palikuonių svorio kitimo tendencijas tarp pirmos ir antros palikuonių kartų. 2. Įvertinti morfologinius pirmos ir antros kartos palikuonių išvaizdos ir elgsenos pokyčius. Tyrime naudotos 12 motininių žiurkių patelių ir 121 palikuonis. Žiurkių maitinimas vyko nustatytomis eksperimento sąlygomis: I eksperimentinės grupės (N=5) žiurkės buvo 50 proc. ribotos maisto 1 mėnesį iki nėštumo ir per visą nėštumo laikotarpį, II eksperimentinės grupės (N=5) žiurkės buvo ribotos 50 proc. maisto 1 mėnesį iki nėštumo, III eksperimentinė grupė (N=2) – kontrolinė, buvo maitinama ad libitum (apie 20 g/p). Vėliau visų grupių žiurkės šertos ad libitum. Palikuonys sverti kartą per savaitę, vertinta metabolinį stresą patyrusių ir nepatyrusių žiurkių palikuonių išvaizda, elgsena ir kiti metabolinio streso požymiai: domėjimasis aplinka, bailumas, agresyvumas, nervingumas. Rezultatai: 1. &#9642; Suaugę pirmos kartos iki nėštumo ir per nėštumą maisto medžiagų ribojimą patyrusių žiurkių vyriškos lyties palikuonys sveria reikšmingai daugiau už kitas grupes; &#9642; Suaugę antros kartos tik iki nėštumo maisto medžiagų ribojimą patyrusių žiurkių vyriškos lyties palikuonys sveria reikšmingai daugiau nei kitų grupių palikuonys... [toliau žr. visą tekstą] / Unsufficient diet before pregnancy or in time of pregnancy can lead to inadequate weight of offspring, delayed maturation as well as obesity and greater risk of noncommunicable diseases in adulthood. The main objective of this study was to explore if there is a change in rat offspring’s body weight that can be attributed to maternal nutrition. Materials and methods. The animals were housed under standard conditions in the vivarium of the Institute of Biochemistry. All animal procedures are in accordance with the The State Food and Veterinary Service. The cohort of 12 mature female Wistar rats was divided into 3 groups with respect to nutritional restriction. The rats were fed either a control (1 group) or restricted diet (2 groups): one experimental group was food-restricted prior to pregnancy and the other - one month prior and through the pregnancy period. Both food-restricted rat groups received 50 percent less of the feed eaten in the control group. After 1 month maternal rats were mated. After weaning all pups were fed with control diet ad libitum. Pups were weighted weekly with the same, calibrated scales. After 4 months female offspring were mated following a standard above mentioned procedure. 2nd offspring generation was kept and weighted under the same standardized conditions. We also observed and evaluated offspring appearance, behavior and other signs of metabolic stress: interest in the environment, fear, aggressiveness, nervousness. Results show that 1... [to full text]
98

Accounting for potential nonlinearity between catch and effort using meta-analysis and applying GLM and GLMM to fishing data from deployments of fixed and mobile gear

Aljafary, Michelle 12 April 2016 (has links)
My thesis examines nonlinearity between catch and effort. I use a meta-analysis of published literature and generalized linear mixed-effects models (GLMM) on both fixed and mobile gear fisheries of Atlantic Canada. The meta-analysis examines the proportionality of catch to effort using the slope of the reduced major axis (RMA) log-log regression, which accounts for “errors-in-variables”. The GLMMs explored proportionality while accounting for variation among fishing vessels. Both analyses found evidence for disproportionality between catch and effort. Catch that increases disproportionally to effort could result from either facilitation or recruitment of effort into the fishery. Catch increases that are less than proportional are expected from competitive interactions among fishers or gear saturation. The GLMM also revealed that the level of aggregation (by set, trip, monthly, or annually) can affect the apparent proportionality between catch and effort. In general, catch and effort should not be considered to be proportional. / May 2016
99

Rybářské obhospodařování Slapské údolní nádrže / Angling Management in the Slapy Riverine Lake

Babický, Jan January 2018 (has links)
The master's thesis focuses on Slapy valley reservoir which is first described as a suitable location for fishing and recreation. Special attention is also paid to its history. The main body of the thesis features the enumeration and characteristics of individual fish species which occur in the reservoir. Furthermore, the thesis deals with the evaluation of the fishing management of the reservoir from 1962 to 2016 considering fish stock and catches of individual species. Factors influencing the development and dynamics of the fish stock are also evaluated. The summary management of Slapy valley reservoir is analyzed in terms of fish stocking and fishing yields. In addition, the population dynamics trends of predatory and non-predatory fish species are analyzed on the basis of fishing catches. In the conclusion, the current condition of the fish stock is evaluated and some minor recommendations for optimizing the fishing management of the reservoir are proposed. KEYWORDS: fish, Slapy, valley reservoir, sport fishing, catch, fish stock, fishing management
100

Transition de poursuite oculaire chez l'homme : vers une compréhension de la constitution d'un modèle interne d'un <<mouvement externe au corps>> / Switching of smooth pursuit in humans : towards an understanding of the constitution of internal model of an "external moving object"

Hainque, Elodie 26 September 2016 (has links)
Afin de poursuivre une cible en mouvement, le système nerveux central (SNC) utilise deux types de mouvements oculaires: la poursuite et les saccades. Les saccades sont des mouvements rapides et brefs de redirection de l’axe visuel d’un centre d’intérêt à un autre. La poursuite est un mouvement lent qui tend à maintenir la cible d’intérêt sur la fovéa. La vitesse de l’œil étant toujours inférieure à celle de la cible, une erreur positionnelle entre l’œil et la cible va croître en l’absence de mouvement correctif. Des saccades de rattrapage sont déclenchées par le SNC pour corriger cette erreur. Alors qu’il est largement reconnu que le système de la poursuite utilise un modèle interne du mouvement de la cible pour améliorer ses capacités, la modalité de contrôle de l’amplitude des saccades de rattrapage est sujette à controverse quant au rôle direct d’afférences sensorielles ou d’un modèle interne de la cible en mouvement. Nous avons développé un nouveau paradigme de transition de poursuite oculaire appliqué à l’Homme sain, dans lequel la cible change de manière imprévisible d’un profil de vitesse non constant périodique à un profil de vitesse non constant apériodique. Nos résultats confirment que le SNC utilise un modèle interne de la cible en mouvement pour contrôler l’amplitude des saccades de rattrapage. Ce modèle se construit progressivement à partir de 168 millisecondes après le changement de profil de vitesse et est utilisé conjointement par les systèmes de la poursuite et saccadique. Le substrat neuronal potentiel de ce modèle interne sera discuté à la lumière des connaissances issues de la littérature concernant le contrôle moteur et oculomoteur. / Two types of eye movements are combined while tracking a moving object: smooth pursuit and saccades. Saccades are rapid redirections of the visual axis between two centers of interest. Because pursuit gain is smaller than one, the eye would increasingly lag behind the target without any correcting movements. Thus, “catch-up saccades” are triggered by the central nervous system (CNS) to cancel this growing position error between the eye and the target. It is widely accepted that an internal model of target motion is used by the CNS to cancel inherent delays between visual input and smooth pursuit motor output, ensuring accurate tracking of moving targets. The amplitude of catch-up saccades triggered during smooth pursuit could be corrected by a delayed sensory signal to account for the ongoing target displacement during catch-up saccades. Yet, recent studies suggested that the correction of catch-up saccade amplitude must also be done through an internal model of target motion. We developed a new paradigm in which the target switches unexpectedly from one target with a non-constant periodic velocity profile to another with a non-constant aperiodic velocity profile. Our results in healthy humans confirm that the CNS uses an internal model of target motion to correct catch-up saccade amplitude. Internal model is being built gradually from 168 ms after the target switch. We show that a common internal model of target motion is shared within the CNS to control smooth pursuit and to correct catch-up saccade amplitude. The potential neuronal substrate of such an internal model will be discussed in the light of the knowledge from the literature on motor and oculomotor control.

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