• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 282
  • 192
  • 21
  • 18
  • 15
  • 4
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 615
  • 237
  • 182
  • 166
  • 114
  • 52
  • 51
  • 51
  • 48
  • 39
  • 39
  • 38
  • 37
  • 33
  • 33
  • 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.
411

A estrutura competitiva da indústria ervateira do Rio Grande do Sul

Antoni, Verner Luis January 1995 (has links)
No presente trabalho descrevem-se e analisam-se as cinco forças competitivas na indústria ervateira do Rio Grande do Sul, segundo o modelo de análise elaborado por Michael Porter e apresentado na obra Estratégia Competitiva de 1986. O método utilizado para a análise da indústria foi o de estudos de caso. Em relação a indústria ervateira do Rio Grande do Sul, constatou-se que apresenta uma estrutura altamente fragmentada, caracterizando-se as empresas, em torno de 70%, como de micro e pequeno porte, sem a presença de líderes no mercado. Empresas de maior porte, médias e grandes, tentam adotar abordagens estratégicas diferenciadas, apoiadas na fixação de marca, na qualificação dos processos de industrialização e de distribuição. Em relação às cinco forças competitivas que afetam a rentabilidade da indústria, constatouse que, por ordem de importância, o poder de barganha dos clientes, o poder de barganha dos fornecedores e a rivalidade dos concorrentes na disputa por grandes clientes devem ser as áreas a que as empresas devem dedicar maior atenção para obterem melhor posicionamento e melhores resultados. / In the present work the five competitive forces in Rio Grande do Sul's Paraguay-tea Industry, according to the analysis model elaborated by Michael Porter and presented in the work "Competitive Strategies" of 1986 are described and analyzed. The method used for the analysis of the industry was case studies. In relation to the Paraguay-tea Industry of Rio Grande do Soul it was noted that it present a highly fragmented structure, around 70% of the companies were characterized as micro and small sized, without the presence of leaders in the market. Larger sized business, try to adopt differenciated boarding strategies locked by the fixation of brands the qualification of industrial processes and distribution. In relation to the five competitive forces that affect the Industry's rentability, it was noted that , by order of importance, the bargaining powers of the clients, the bargaining power of the suppliers and the rivalry of the competitors in the dispute of large clients should be the areas to which companies should dedicate more attention in order to obtain better placement and better results.
412

A governança na cadeia agro-industrial da erva-mate na região do Alto Uruguai Rio-grandense, sob a ótica da cadeia de suprimentos

Mosele, Sérgio Henrique January 2002 (has links)
O setor ervateiro, na microrregião de Erechim, compreende 9.363 famílias de produtores rurais, que têm na atividade ervateira uma importante fonte de renda e 42 empresas agroindústrias que produzem e comercializam erva-mate para diversas regiões do Brasil e também para exportação. Para o desenvolvimento do trabalho foram selecionadas, de sete estabelecimentos varejistas, seis agroindústrias privadas, uma agroindústria privada cooperativa e vinte e quatro produtores rurais. No presente estudo, buscou-se: Caracterizar as cadeias de suprimentos de seis empresas privadas e uma empresa privada cooperativa. Descrever os fluxos de informações, de produtos, de recursos e de serviços. Verificar se existe uma lógica de mercado ou um maior poder de barganha de alguns elos sobre outros nas cadeias de suprimentos. Verificar a influência do fluxo de informações, de produtos, de recursos e de serviços na governança das cadeias estudadas, verificar a estrutura de governança nas cadeias de suprimentos em estudo. O trabalho conclui que o conhecimento dos fluxos de informações, de produtos, de recursos e de serviços, associados ao conhecimento do canal de distribuição, permite uma melhor compreensão da cadeia de suprimentos e da cadeia genérica, de seus potenciais e de seus gargalos. Também se concluiu que o custo de colheita é um dos problemas mais relevantes para os produtores e que, associado a dificuldades no fluxo de informações, cria dificuldades que precisam ser resolvidas. Quanto às agroindústrias, elas têm diversas dificuldades, entre elas, o maior poder de barganha do varejo sobre as agroindústrias como na comercialização com as grandes redes de hipermercados, que impõe uma série de normas as quais acabam por elevar os custos destas empresas. Espera-se que os conhecimentos gerados neste trabalho possam contribuir para a elaboração de políticas setoriais, estratégias empresariais e proposições de ferramentas gerenciais que possam melhorar a eficiência e a eficácia desta cadeia na região do Alto Uruguai Rio-grandense.
413

Compostos fenolicos em erva-mate e frutas / Phenolic compounds in ¿erva-mate¿ and fruits

Ribani, Rosemary Hoffmann 22 February 2006 (has links)
Orientador: Delia Rodriguez-Amaya / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T17:12:33Z (GMT). No. of bitstreams: 1 Ribani_RosemaryHoffmann_D.pdf: 594684 bytes, checksum: 21a6d1bcc7111e6b7565998243867631 (MD5) Previous issue date: 2006 / Doutorado / Doutor em Ciência de Alimentos
414

Não mate a mata: visões ambientais precursoras na obra musical de Adelson Santos

Saunier, Karine Aguiar de Sousa, (11) 94141-2851 31 March 2017 (has links)
Submitted by Alisson Leda (alisson-brasil@outlook.com) on 2018-04-27T18:04:57Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Karine A S SAUNIER_ Não mate a mata [2017].pdf: 45983303 bytes, checksum: d270799e84723fc541372e72bfd0c2e6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-04-30T13:11:10Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Karine A S SAUNIER_ Não mate a mata [2017].pdf: 45983303 bytes, checksum: d270799e84723fc541372e72bfd0c2e6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-04-30T13:16:45Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Karine A S SAUNIER_ Não mate a mata [2017].pdf: 45983303 bytes, checksum: d270799e84723fc541372e72bfd0c2e6 (MD5) / Made available in DSpace on 2018-04-30T13:16:45Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Karine A S SAUNIER_ Não mate a mata [2017].pdf: 45983303 bytes, checksum: d270799e84723fc541372e72bfd0c2e6 (MD5) Previous issue date: 2017-03-31 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / For at least 35 years, Argumento has become one of the best-known works of the Amazonian songbook by the name of Nao Mate a mata, since it received its first record in the Simple Compact LP Adelson (1980) and was played in the main Amazonian radios. Authored by the singer-songwriter, Adelson Santos, the work is recognized by artists and lovers of local music as a true ode to environmental conservation in the Amazon. The song reached social recognition only in 1980, positioning Adelson Santos as the most representative Amazon composer. The sociocultural context in which this artist began to reflect on the environmental problem through his music was marked by a series of important events for the consolidation of the Ecological Movement around the world. In its more than 40 years of creation, this musical piece has demonstrated its pioneering and timeless character, metamorphosing in arrangements from Boi-bumbá to instrumental jazz, re-readings performed by artists from different generations and different musical segments in the State of the Amazon. With the accomplishment of this study, we aim much more than to make just an inventory of the ecological songs of Adelson Santos, to analyze from the perspective of ethnomusicology and anthropology of the musical performance his most important work Argument, or simply to reconstruct configurative traits of his biography for prove its condition as an ecological subject. The radical critique of the environmental crisis contained in the work of Adelson Santos is seen by us as another possibility to reaffirm the position of centrality of Culture in the discussion on Sustainable Development worldwide in the post 2015. In seeking to establish an interface between the production of musical sounds, nature and sustainability, we are also creating a space for the valorization of multiple discourses and knowledge, as well as the many ecological subjects existing outside a naturalistic tradition, since Ecology, in present day, is assumed as a migrant idea, finding itself very close to social movements. In revealing these ecological subjects outside the areas of knowledge of naturalistic tradition, we want to provoke a discussion about the interdisciplinary and aggregating vocation of Environmental Sciences, as well as Music itself, based on the new theoretical orientation proposed by Ecomusicology and also of the already consolidated field of ethnomusicology. We promote a discussion of the ecology of knowledge and new perspectives for the reform of scientific thought and the deconstruction of the old models of technoscience that still prevent the existence of a reciprocity between the various forms of reproduce and know the world we live in. / Há pelo menos 35 anos a composição Argumento tornou-se uma das mais conhecidas obras do cancioneiro amazonense pelo nome de Não mate a mata, desde que recebeu seu primeiro registro fonográfico no LP Compacto Simples Adelson (1980) e passou ser tocada nas principais rádios amazonenses. De autoria do cantautor manauara Adelson Santos, a obra é reconhecida por artistas e apreciadores da música local como uma verdadeira ode à conservação ambiental na Amazônia. A canção atingiu reconhecimento social apenas em 1980, posicionando Adelson Santos como o mais representativo “cantautor ecológico” amazonense. O contexto sociocultural no qual este artista começou a refletir sobre a problemática ambiental por meio de sua música, esteve marcado por uma série de eventos importantes para a consolidação do Movimento Ecológico em todo o mundo. Em seus mais de 40 anos de criação, a referida peça musical tem demonstrado seu caráter precursor e atemporal, metamorfoseando-se em arranjos desde o Boi-bumbá ao Jazz instrumental, de releituras de realizadas por artistas de diversas gerações e segmentos musicais distintos no Estado do Amazonas. Com a realização deste estudo, objetivamos muito mais do que realizar apenas um inventário das canções ecológicas de Adelson Santos, analisar sob a perspectiva da etnomusicologia e da antropologia da performance musical sua mais importante obra Argumento, ou simplesmente, reconstruir traços configurativos de sua biografia para comprovar a sua condição de sujeito ecológico. A crítica radical à crise ambiental contida na obra de Adelson Santos é vista por nós como mais uma possibilidade para reafirmar a posição de centralidade da Cultura na discussão sobre o Desenvolvimento Sustentável em todo o mundo no pós-2015. Ao buscarmos estabelecer uma interface entre a produção de sons musicais, natureza e sustentabilidade, estamos também criando um espaço para a valorização de múltiplos discursos e saberes, bem como dos inúmeros sujeitos ecológicos existentes fora de uma tradição naturalista, uma vez que a Ecologia, nos dias atuais, se assume como ideia migrante, encontrando-se em posição bastante próxima aos movimentos sociais. Ao revelarmos estes sujeitos ecológicos fora das áreas do conhecimento de tradição naturalista, queremos provocar uma discussão acerca vocação interdisciplinar e agregadora das Ciências do Ambiente, bem como, da própria Música a partir da novíssima orientação teórica proposta pela Ecomusicologia e, também, do já consolidado campo da Etnomusicologia. Fomentamos com isto uma discussão acerca da ecologia de saberes e, ainda, novas perspectivas para a reforma do pensamento científico e a desconstrução dos velhos modelos da tecnociência que ainda impedem a existência de uma reciprocidade entre as diversas formas de reproduzir e conhecer o mundo em que vivemos.
415

Efeitos da ingestão de cafeína, café (Coffea arabica) e chá mate (Ilex paraguariensis) sobre a atividade lipolítica do tecido adiposo e parâmetros metabólicos em ratos submetidos ao exercício físico / Effects of the ingestion of caffeine, coffee (Coffea arabica) and roasted maté tea (Ilex paraguariensis) on the adipose tissue lipolytic activity and metabolic parameters on rats submitted to physical exercise

Luciane Arias Saldanha 04 May 2012 (has links)
Introdução. O estoque excessivo de lipídeos no organismo está associado à diversas doenças crônicas não transmissíveis. O exercício físico aumenta a utilização dos lipídeos. A mobilização dos ácidos graxos (AG) é a primeira etapa para que eles sejam utilizados como fonte energética pelo músculo esquelético. Para otimizar esse processo, têm sido estudadas substâncias que poderiam aumentar a lipólise, como a cafeína. O café e o chá-mate contêm cafeína em sua composição. Objetivo. Comparar os efeitos da ingestão de cafeína, café e chá-mate sobre o desempenho físico, parâmetros metabólicos e lipólise em resposta ao exercício físico agudo em esteira rolante, em ratos Wistar. Métodos. O estudo foi divido em etapas 1 (exercício até a exaustão, n=15) e 2 (exercício com duração de 60 minutos, n=45). A amostra foi composta por cinco grupos: controle (C), controle exercício (CE), cafeína exercício (CFNE), café exercício (CAFE) e chá-mate exercício (CME). Na etapa 1, foram comparados o desempenho, as diferenças na massa corporal e na glicemia (pós versus pré-exercício) e a atividade lipolítica. Na etapa 2, foram comparadas as diferenças na massa corporal e na glicemia (pós versus pré-exercício), a atividade lipolítica, o lactato sanguíneo e o glicogênio muscular. Os dados foram apresentados segundo a estatística descritiva (média ± erro padrão). Os dados foram analisados através de modelos gerais lineares e os deltas através da técnica de contrastes ortogonais. Para verificar associação entre as variáveis de interesse foi utilizada a correlação linear de Pearson. Resultados. Na etapa 1 não foram observadas diferenças entre os grupos com relação ao desempenho. A massa corporal pós-exercício, quando comparada à pré-exercício, diminuiu nos grupos CE (188 por cento ), CFNE (273 por cento ), CAFE (319 por cento ) e CME (204 por cento ), quando comparados ao C. Não houve diferença para a variação de glicemia entre os grupos. Observou-se aumento de 92 por cento da lipólise no grupo CAFE, quando comparado ao grupo C. Na etapa 2, houve diminuição da massa corporal (pós versus pré-exercício) nos grupos CE e CFNE (263 por cento ), CAFE (230 por cento ) e CME (183 por cento ), quando comparados ao C. A glicemia aumentou nos grupos CFNE (variação pós versus pré-exercício de 343 por cento e 220 por cento , quando comparada aos grupos C e CE, respectivamente) e CME (179 por cento , quando comparada ao C). A lipólise estava aumentada nos grupos CFNE e CAFE, quando comparados aos grupos C (150 por cento e 233 por cento , respectivamente) e CE (51 por cento e 101 por cento , respectivamente). Não foram observadas diferenças significantes entre os grupos para a concentração sanguínea de lactato e para o conteúdo de glicogênio muscular. Não houve correlação entre as variáveis, em ambas as etapas. Conclusão. Após o exercício até a exaustão, o grupo que ingeriu café apresentou aumento da atividade lipolítica. Após 60 minutos de exercício, o grupo que ingeriu cafeína, assim como o que ingeriu chá-mate, apresentou aumento da glicemia. A cafeína e o café promoveram aumento da lipólise / Introduction. The excess of body fat is associated with the development of chronic non-communicable diseases. Physical exercise enhance lipolysis. The mobilization of fatty acids (FA) is the first stage for the use of lipids as a source of energy by skeletal muscle. In order to increase the use of FA, substances have been used. Objective. This work compared the effects of caffeine, coffee and maté tea on the performance, metabolic parameters and lipolysis in response to acute physical exercise on a treadmill, in Wistar rats. Methods. The study was developed in stage 1 (exercise until exhaustion, n=15) and stage 2 (exercise lasting for 60 minutes, n=45). The design consisted of groups: control (C), control exercise (CE), caffeine exercise (CFNE), coffee exercise (CAFE) and maté tea exercise (CME). For stage 1, the performance, the differences in the total body mass and glucose (post- versus pre-exercise), and lipolytic activity were compared. For the stage 2, comparisons were made among the differences in the total body mass and glucose (post- versus pre-exercise), lipolytic activity, blood lactate level and muscular glycogen content. The data were presented as average ± standard error. The data were analyzed by means of general linear models and the deltas by the orthogonal contrasts technique. Pearsons linear correlation was used to check the association between the variables of interest. Results. In stage 1, no differences were observed between the groups in terms of performance. The post-exercise total body mass, when compared to the pre-exercise, decreased for the CE (188 per cent ), CFNE (273 per cent ), CAFE (319 per cent ) e CME (204 per cent ) groups, when compared to C. There was no difference for glucose (post- versus pre-exercise) between groups. An increase of 92 per cent in lipolysis was observed in the CAFE group, when compared to C. In stage 2, there was a decrease in the post-exercise total body mass, when compared with pre-exercise, in the CE and CFNE (263 per cent ), CAFE (230 per cent ) and CME (183 per cent ) groups. An increase in post-exercise glucose, in comparison with the pre-exercise, was observed in groups CFNE (343 per cent and 220 per cent , when compared to C and CE, respectively) and CME (179 per cent ), when compared to C. Lipolysis increased for the CFNE and CAFE groups when compared to groups C (150 per cent and 233 per cent , respectively) and CE (51 per cent and 101 per cent , respectively). No significant differences were observed between the groups for the blood lactate and the muscular glycogen levels. It wasn\'t observed correlation between the different variables, for stage 1 and 2. Conclusion. Following exercise until exhaustion, the group which ingested coffee presented an increase in the lipolytic activity. After exercise lasting 60 minutes, the group which ingested caffeine, as well as that which ingested maté tea, presented increased levels of glucose. The animals which ingested caffeine or coffee presented increased levels of lipolysis
416

Évolution et mécanismes d’évitement de la consanguinité chez un hyménoptère parasitoïde Venturia canescens / Evolution and mechanisms of inbreeding avoidance in a parasitoid wasp, Venturia canescens

Collet, Marie 20 December 2017 (has links)
La consanguinité est connue par les biologistes pour diminuer la valeur sélective des individus en diminuant par exemple leur survie ou leur fertilité. De ce fait, la sélection naturelle devrait favoriser l'apparition de comportements permettant l'évitement des accouplements entre apparentes pour limiter les conséquences néfastes dues à la dépression de consanguinité. Cette dépression de consanguinité est particulièrement visible chez les Hyménoptères avec un système de détermination du sexe appelé single-locus Complementary Sex Determination (sl-CSD), où elle amène à la production de males diploïdes non viables ou stériles. Mon travail de thèse a ainsi consiste à étudier le phénomène d'évitement d'accouplements entre apparentes dans des populations naturelles d'un hyménoptère parasitoïde avec sl-CSD, Venturia canescens, ainsi que des signaux utilisés par les femelles pour déterminer l'apparentement qu'elles ont avec les individus qu'elles rencontrent. Nous avons d'abord étudié le lien unissant type d'habitat (continental, iles ou laboratoire), diversité génétique et production de males diploïdes dans 11 populations de V. canescens. En effet, un cadre théorique nomme "Vortex d'extinction du aux males diploïdes" prédit une corrélation négative entre isolations des populations, diversité génétique et production de males diploïdes pouvant amener à l'extinction de populations d'Hyménoptères. Nous avons ainsi démontré une corrélation négative entre diversité génétique et production de males diploïdes dans les populations isolées de V. canescens. Ensuite, il a été montré précédemment que les femelles de cette espèce étaient capables de discriminer les males qui leur étaient apparentes et d'éviter les accouplements entre apparentes en laboratoire. Nous nous sommes ainsi intéressés à ce phénomène d'évitement d'accouplement entre apparentes dans des populations naturelles grâce au génotypage de 450 individus du terrain et leur descendants. Nous avons montré que les femelles toléraient les accouplements entre apparentes sur le terrain ainsi qu'en laboratoire en présence de plusieurs males, nous permettant de mettre en lumière l'importance des conditions environnementales sur le choix du partenaire sexuel. Nous nous sommes enfin concentrés sur le système de reconnaissance des apparentes au niveau mécanistique en étudiant les signaux chimiques utilisés par les femelles pour reconnaitre leurs apparentes dans deux contextes écologiques différents, le choix du partenaire sexuel et l'évitement du superparasitisme lors de la ponte. Nous avons ainsi montré des similitudes entre les compositions chimiques de ces deux signaux mais aussi qu'ils n'étaient pas interchangeables entre les deux contextes écologiques étudiés. Au final, les résultats obtenus apportent un nouvel éclairage sur les conditions nécessaires à l'apparition d'un évitement d'accouplements entre apparentes dans des populations naturelles ainsi que sur les signaux utilisés lors de la reconnaissance de parentèle chez un hyménoptère parasitoïde / Inbreeding is well known by biologists to lower the fitness of individuals by or example decreasing survival or fertility. Therefore, natural selection should favour behaviours preventing the reproduction of genetically-related individuals or mitigating harmful consequences, called inbreeding depression. Inbreeding depression is particularly visible in Hymenoptera with a sex-determination system called single-locus Complementary Sex Determination (sl-CSD), where it leads to the production of diploid males that are either unviable or sterile. My PhD work has thus been devoted to the study of sib-mating avoidance in natural populations of a parasitoid with sl-CSD, Venturia canescens, and to understand the cues used by females recognize their kin. We first studied the link between habitat type (continental, island or captive), genetic diversity and diploid male production in 11 V. canescens populations. Indeed, a theoretical framework called "Diploid male extinction vortex" predict a negative correlation between populations’ isolation, genetic diversity and diploid male production that could lead to the extinction of hymenopteran populations.We actually showed a negative correlation between genetic diversity and diploid male production in isolated populations. Previous studies have furthermore demonstrated kin discrimination and sib-mating avoidance by V. canescens females in the laboratory. We therefore studied the sibmating avoidance behaviour in natural populations of this species by genotyping more than 450 wild individuals and their offsprings. We demonstrated that females tolerated inbreeding in the wild as well as in the laboratory when several males were present. We highlighted the importance of environmental conditions on mate choice. At last, we were interested in the kin recognition system and researched the chemical cues used by females in two ecological contexts, mate choice and superparasitism avoidance. This allowed us to identify similarities in the composition of the two chemical signals and that they were not interchangeable between the two studied ecological contexts. In the end, the results we obtained shed new light on the necessary conditions for the apparition of sib-mating avoidance in natural populations, as well as on the cues used for kin recognition in a parasitoid
417

Coevolution of male signals and female preferences in <em>Drosophila montana</em> and <em>D. virilis</em>

Saarikettu-Känsälä, M. (Mari) 30 November 2011 (has links)
Abstract Divergence of behavioral traits (e.g. courtship rituals, habitat choice) has had a major impact on species formation and isolation. Species-specific courtship rituals preventing species hybridization may arise as a by-product of natural selection during spatial isolation or through direct action of natural selection to prevent species hybridization after a secondary contact. Coordination leading to the assumption of coevolution of signals and preferences is a prerequisite for effective courtship signaling between a male and a female of the same species. We found a reasonable amount of variation in the mate traits within the Drosophila montana and D. virilis species, but our findings did not reveal evidence of the coevolution between the male courtship signals and female preference for these signals. Variation also did not cause isolation within species. The form of female preference for carrier frequency of male song was found to be stabilizing even in changing environments, when female preference for the carrier frequency and pulse length of the male song was measured at ambient temperature. D. montana females always preferred males with high frequency songs, which probably advertises the male condition. The frequency of male song decreased due to male aging, although males with larger body size were able to maintain frequencies better. Ageing also had a deterioration effect on male reproductive success. The importance of male courtship song was not only highlighted in mate choice, but also in species-recognition. We were able to persuade D. montana females to copulate with alien D. lummei species by playing them simulated song resembling the song of conspecific males. Simulated courtship songs were demonstrated to be a practical tool in studies of preference between sexually isolated Drosophila species. / Tiivistelmä Kosintapiirteiden (esim. kosintarituaalit, habitaatin valinta) vaihtelevuudella on ollut suuri vaikutus lajien muodostumisessa ja eriytymisessä. Lajien välisiä risteytymisiä estäviä lajispesifisiä kosintarituaaleja voi syntyä luonnonvalinnan sivutuotteena spatiaalisen eristäytymisen aikana tai luonnonvalinnan suoralla vaikutuksella estämään lajiristeymät lajien uudelleen kohdatessa. Tehokkaan koiraan ja naaraan välisen kosintaviestinnän edellytyksenä on koordinointi, minkä vuoksi on oletettavaa, että signaalien ja vasteiden välillä on yhteisevoluutiota. Löysimme kohtuullisen määrän vaihtelevuutta kosintapiirteissä Drosophila montana – ja D. virilis – lajeilla, mutta emme löytäneet todisteita koiraan kosintasignaalien ja naaraan näihin signaaleihin kohdistamien vasteiden välisestä yhteisevoluutiosta. Vaihtelu ei myöskään aiheuttanut isolaatiota lajien välille. Naaraan koiraan kosintalaulun kantofrekvenssiin osoittaman vasteen funktion muodon havaittiin olevan tasapainottava jopa vaihtelevissa ympäristöissä, kun naaraan kantotaajuuteen osoittamaa vastetta mitattiin eri lämpötiloissa. D. montana naaraat suosivat koiraita, joilla oli korkeataajuinen kosintalaulu. Laulun korkea taajuus kertoo luultavasti naaraalle koiraan fyysisestä kunnosta. Koiraan laulun frekvenssin havaittiin laskevan koiraan ikääntyessä, mutta isommat koiraat pystyivät paremmin säilyttämään korkean taajuuden laulussaan. Ikääntyminen heikensi myös koiraan lisääntymismenestystä. Koiraan kosintalaulun tärkeys ei korostunut pelkästään parinvalinnassa, vaan myös lajintunnistuksessa. Pystyimme suostuttelemaan D. montana –naaraat parittelemaan vieraan D. lummei –lajin kanssa käyttämällä simuloituja kosintalauluja, jotka osoittautuivat käytännöllisiksi välineiksi tutkittaessa naaraan vasteita seksuaalisesti eriytyneillä Drosophila-lajeilla.
418

Factors affecting the demography of a lek-mating bird: the greater prairie-chicken

Nooker, Jacqueline Kay January 1900 (has links)
Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Sexual selection via female choice and male-male aggression leads to elaboration of male traits. If male traits correlated with reproductive success are honest signals of male quality, survival costs may be associated with the expression of those traits. Testosterone (hereafter ‘T’) may enhance male breeding success, but T can also reduce immunocompetence and survival. Socially monogamous male birds with higher circulating T experience reproductive advantages, but the role of T in lek mating systems is largely unknown. To address these issues, I individually marked and conducted focal behavioral observations of greater prairie-chickens (Tympanuchus cupido) at five lek sites over a 5-year period. Females were fitted with radio-telemetry to monitor nesting success and survival. I examined the relationship between male traits and mating success using multinomial discrete choice models, a statistical method not previously applied to studies of sexual selection. Male mating success was highly skewed at greater prairie-chicken leks with 18.5% of males obtaining 87.2% of all successful copulations (n = 108 males; 85 copulations). Mating success was influenced most by male behavior, followed by several morphological attributes. The role of T was quantified using blood samples and by experimentally implanting a subset of males with T. T did not consistently affect mating success. Non-territorial males had lower T levels than territorial males. Among territory holders, T was unexpectedly negatively correlated with mating success. However, the odds of receiving a copulation were 4.3 times (0.42 to 45.3) greater for T-implanted males than males with sham implants. Future work should explore the interactions among the immune system, parasite load, and mating success of prairie-chickens. Annual survival of male prairie-chickens was not related to mating success, behavior, age or T level, suggesting there is no cost of increased male mating success. Like males, reproductive success of females was also highly skewed because < 10% of nests successfully hatched young. Comparisons of seasonal and annual survival rates indicate that females experience increased mortality during the breeding season relative to the nonbreeding season. Synthesis of field estimates of demographic parameters indicates prairie-chicken populations will decline without changes in rangeland management to reduce predator numbers or provide more nesting cover.
419

Les éléments de l'attractivité féminine et leurs variations / Women's attractiveness components and their variations

Bovet, Jeanne 09 December 2014 (has links)
Dans le cadre du choix de partenaire, les préférences sont des mécanismes psychologiques permettant aux individus de choisir un (ou une) partenaire susceptible d'augmenter leur succès reproducteur. Comme le nombre de descendants d'un homme dépend largement de la fertilité de la (ou des) partenaire(s) qu'il choisit, la capacité à détecter et à préférer les femmes ayant une fertilité importante a été sélectionnée. Et puisque la fertilité d'une femme est en partie déductible de certaines caractéristiques physiques, l'attractivité féminine est en grande partie physique. Une approche expérimentale a été utilisée afin d'identifier les traits physiques influençant l'attractivité féminine, ainsi que les composantes de la fertilité desquelles ils sont les indices. En plus des indices connus de fertilité immédiate (c'est à dire la capacité d'une femme à engendrer un descendant à un moment donné), nos résultats montrent que les hommes sont également sensibles à des indices de fertilité résiduelle (nombre potentiel d'enfants qu'une femme pourra avoir dans le futur), partiellement définie par l'âge à la ménopause. Les moyens de détection de ces traits par les hommes ont également été analysés, démontrant l'importance de la vision périphérique lors de l'évaluation de l'attractivité d'un corps féminin. La question de l'universalité de ces critères d'attractivité a ensuite été abordée. Les différentes études montrent que les préférences masculines varient temporellement (la silhouette idéale, mesurée par le ratio taille/hanche, varie depuis le XVe siècle), géographiquement (les préférences pour la fertilité résiduelle diffèrent entre la France et l'Indonésie) et individuellement (on observe une préférence pour l'homogamie pour les traits du visage). Si nos résultats réfutent donc l'idée d'une beauté unique, universelle et biologiquement fixée, ces variations sont loin d'être arbitraires. Les variations des préférences s'expliquent par différents compromis et enjeux évolutifs, variant en fonction de conditions environnementales, culturelles, et individuelles. / In a context of mate choice, preferences are psychological mechanisms allowing individuals to choose a partner who can enhance their reproductive success. As a man's number of children greatly depends on the fertility of his mate(s), the ability to detect and prefer women with a high fertility has been selected. Moreover, as a woman's fertility is linked to various physical features, female attractiveness is largely physical. An experimental approach has been used to identify the physical traits influencing women's attractiveness, as well as the fertility characteristics of which they are the cues. In addition to well known cues of current fertility (i.e. a woman's ability to conceive a child at that given time), our results show that men are also sensitive to cues for residual fertility (i.e. the potential number of children a woman could have in the future), which is partially determined by age at menopause. Male means of detecting these features have been analysed too, highlighting the crucial role of the peripheral vision when judging the attractiveness of a woman's body. Furthermore, the issue of whether these attractiveness standards are universal has been addressed. Our studies show that men's preferences vary through time (the ideal body shape, determined by the waist-to-hip ratio, has changed since the 15th century), geographically (preferences concerning the residual fertility differ between France and Indonesia), and individually (a preference for homogamy has been found within facial features). Thus, our results disprove the notion of a single, universal and biologically fixed idea of beauty. But these variations of preferences are not arbitrary, and can be explained by evolutionary stakes and trade-offs, linked to environmental, cultural and individual conditions.
420

Identificação da procedência geográfica da erva mate (llex paraguariensis) mediante análise elementar, reflexão no infravermelho próximo e quimiometria

Marcelo, Marcelo Caetano Alexandre January 2013 (has links)
Neste trabalho foi desenvolvido um método de análise de erva mate mediante as técnicas de espectroscopia no infravermelho próximo (NIR), espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) e espectrometria de massa com plasma indutivamente acoplado (ICP-MS), com o intuito de classificar a erva mate por país de origem da América do Sul. Para isto, foram utilizados métodos de análise multivariada supervisionada e não supervisionada, como a análise hierárquica por agrupamentos (HCA), a análise por componentes principais (PCA), o método do k-ésimo vizinho mais próximo (kNN), soft independent modeling class analogy (SIMCA), análise discriminante por mínimos quadrados parciais (PLS-DA) e análise discriminante por máquinas de vetor de suporte (SVM-DA). Foram analisadas 54 amostras de erva mate provenientes da América do Sul (Argentina, Brasil, Paraguai e Uruguai). As amostras foram cominuídas em moinho criogênico e diretamente analisadas para a obtenção dos espectros de reflexão no NIR. Para a determinação dos elementos Ca, K, Mg, Al, Fe, Mn, Ba, Cu, P, Sr e Zn por ICP OES e Li, Be, Ti, V, Cr, Ni, Co, As, Se, Rb, Mo, Ag, Cd, Sb, La, Ce, Pb, Bi e U por ICP-MS, foi realizada a decomposição das amostras por via úmida em bloco digestor em sistema fechado. A classificação da erva mate por país de origem foi possível, sendo que a melhor classificação para todos os métodos de análise multivariada foi obtida por NIR e para as concentrações dos elementos avaliados, a SVM-DA foi o melhor. Conclui-se que a erva mate pode ser avaliada por país de origem mediante a técnicas de ICP OES, ICP-MS e NIR. / A method of yerba mate analyzis using near infrared spectroscopy (NIR), inductively coupled plasma optical emission spectrometry ( ICP OES ) and inductively coupled plasma mass spectrometry (ICP-MS) was developed in order to classify yerba mate by country of origin in South America. To this end, principal components analysis (PCA), k-nearest neighbor (KNN), soft independent modeling class analogy (SIMCA), partial least square discriminant analysis (PLSDA), discriminant analysis by vector machine (SVM-DA) were used for multivariate analysis of the NIR spectra and element concentrations found in 54 samples of yerba mate from South America (Argentina, Brazil, Paraguay and Uruguay ). The samples were ground in cryogenic mill and directly analyzed in order to obtain the reflectance spectra in the NIR region. For elements determination (Ca, K, Mg, Al, Fe, Mn, Ba, Cu, P, Sr and Zn by ICP OES and Li, Be, Ti, V, Cr, Ni, Co, As, Se, Rb, Mo, Ag, Cd, Sb, La, Ce, Pb, Bi and U by ICP-MS), the samples were acid digested in closed vessel in digestion block. The classification of the yerba mate by country of origin was possible, whereas the best classification using all multivariate analysis methods was obtained for NIR. For the element concentrations, the best classification was obtained by SVM-DA. It was concluded that yerba mate classification by country of origin can be assessed through ICP OES, ICP-MS and NIR.

Page generated in 0.0347 seconds