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| Registros recuperados: 76 | |
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| León Herrera, Albert. |
| El objetivo de esta investigación fue comparar el método propuesto por Harry Markowitz (media y varianza) y el método propuesto por Javier Estrada (media-semivarianza), en la elección de un portafolio de inversión, conformado por una mezcla diversificada de cultivos agrícolas. Los datos trabajados fueron rentabilidades de cinco productos agrícolas, mismos que fueron deflactados y de ellos se obtuvieron las ganancias del periodo 1979-2009. Ganancias que nos permitieron calcular la matriz de covarianzas de los productos agrícolas por ambos métodos. Posteriormente se realizo una simulación de 100 repeticiones de tamaño n=30, para obtener las rendimientos de cada producto mediante ambos métodos de solución, para presentar un histograma de frecuencias de cada... |
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Palavras-chave: Portafolio de inversión; Diversificación; Rentabilidad; Ganancia; Portfolio investment; Diversification; Profitability; Profit; Desarrollo rural; Maestría. |
| Ano: 2012 |
URL: http://hdl.handle.net/10521/664 |
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| Blythe, Jessica L.; University of Victoria; jessica.blythe@jcu.edu.au; Murray, Grant; Vancouver Island University; grant.murray@viu.ca; Flaherty, Mark; University of Victoria; flaherty@office.geog.uvic.ca. |
| Change is a defining characteristic of coastal social-ecological systems, yet the magnitude and speed of contemporary change is challenging the adaptive capacity of even the most robust coastal communities. In the context of multiple drivers of change, it has become increasingly important to identify how threatened communities adapt to livelihood stressors. We investigate how adaptation is negotiated in two coastal fishing communities by documenting livelihood stressors, household assets, adaptive strategies, and factors that facilitate or inhibit adaptation. Declining catch is the most common stressor being experienced in both communities, however, socioeconomic, e.g., disease or theft, and ecological, e.g., severe storms and drought, changes are also... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptation; Africa; Diversification; Intensification; Livelihoods; Small-scale fisheries. |
| Ano: 2014 |
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| The concept of resilience is widely promoted as a promising notion to guide new approaches to ecosystem and resource management that try to enhance a system's capacity to cope with change. A variety of mechanisms of resilience specific for different systems have been proposed. In the context of resource management those include but are not limited to the diversity of response options and flexibility of the social system to adaptively respond to changes on an adequate scale. However, implementation of resilience-based management in specific real-world systems has often proven difficult because of a limited understanding of suitable interventions and their impact on the resilience of the coupled social-ecological system. We propose an agent-based modeling... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive management; Agent-based model; Amudarya; Diversification; Fisheries; Irrigation; Mechanism; Resilience; River basin; Social-ecological system; Water use.. |
| Ano: 2007 |
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| Chalmandrier, Loic; Albouy, Camille; Descombes, Patrice; Sandel, Brody; Faurby, Soren; Syenning, Jens-christian; Zimmermann, Niklaus E.; Pellissier, Loic. |
| Reconstructing the processes that have shaped the emergence of biodiversity gradients is critical to understand the dynamics of diversification of life on Earth. Islands have traditionally been used as model systems to unravel the processes shaping biological diversity. MacArthur and Wilson's island biogeographic model predicts diversity to be based on dynamic interactions between colonization and extinction rates, while treating islands themselves as geologically static entities. The current spatial configuration of islands should influence meta-population dynamics, but long-term geological changes within archipelagos are also expected to have shaped island biodiversity, in part by driving diversification. Here, we compare two mechanistic models providing... |
| Tipo: Text |
Palavras-chave: Allopatric speciation; Continental drift; Dispersal; Diversification; Meta-population model; Neutral model. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00602/71377/69825.pdf |
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| Thebaud, Olivier; Innes, James; Norman-lopez, Ana; Slade, Stephanie; Cameron, Darren; Cannard, Toni; Tickell, Sharon; Kung, John; Kerrigan, Brigid; Williams, Lew; Little, L. Richard. |
| An economic survey of the commercial operators currently active in the Queensland Coral Reef Fin-Fish Fishery has been carried out, as part of a research project aimed at evaluating alternative management options for this fishery. This paper presents the background analysis used as a basis to develop the sampling design for this survey. The background analysis focuses on activity patterns of the fleet based on effort and catch information, as well as patterns of quota ownership. Based on this information, a fishing business profile describing the micro-economic structure of fishing operations is developed. This profile, in conjunction with the qualitative information gained in undertaking the economic surveys, allows preliminary understanding of the key... |
| Tipo: Text |
Palavras-chave: Commercial fishing; Queensland Coral Reef Fin-Fish Fishery; Great Barrier Reef; Business structures; ITQs; Diversification. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00250/36166/34749.pdf |
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| Fontaine, Pascal; Legendre, Marc; Vandeputte, Marc; Fostier, Alexis. |
| How may fish domestication participate in sustainable development of aquaculture? The development of fish farming currently compensates for the stagnation of fishery catches while the market demand continues to increase. The development of fish farming relies on an active diversification of farmed fish species. A diversification based on the farming of native species could reduce the environmental impact of fish culture and could better fit to needs of local markets. Such development could also favour a more integrated local economy. In this context, the building of a generic approach for multi-species domestication is required to optimise the use of the technical and financial means available for fish culture diversification. |
| Tipo: Text |
Palavras-chave: Sustainable development; Fish culture; Domestication; Diversification. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6557.pdf |
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| Méro, David. |
| Finfish farming diversification is a reality nowadays in France: this work brings the interest of the whole commodity chain for new fish species. This report identifies the species criterions of choice from inquiries beside professionals of the commodity chain, proposes a selection method and tackles, in example, the choice of new species for fish farming in cages on the west coasts of France, from Bay of Biscay to the North Sea. ' Method is divided in two stages: firstly an elimkation stage, which aims are to select from the 25 000 fish species, potential species by using redhibitory postulates, secondly a position stage which classifies the remaining species. A list of 53 species is proposed. Selection has been stopped because of the shortage of data.... |
| Tipo: Text |
Palavras-chave: Aquaculture; Pisciculture; Diversification; Nouvelles espèces; Poissons marins; Aide à la décision; Sélection multicritère; Marché; Transformation. |
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00622/73448/72687.pdf |
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| Quemener, Loic; Suquet, Marc; Mero, David; Gaignon, Jean-louis. |
| At present, European marine fish farming is based on sea bream and sea bass. A trend for diversification is sustained by the diversity of environmental conditions, by the availability of new production techniques such as recirculating systems, by an increase in rearing yields, by new market trends and by the possibilities to reduce risks of disease outbreak. Already reared fish species were chosen considering a limited number of criteria such as a high selling price and the availability of juveniles or breeders in the wild. This paper proposes a new selection method of fish species as candidates for aquaculture development on the French Atlantic, the Channel and the North Sea coasts. Using a three-phase procedure, candidates were selected among 20 000 fish... |
| Tipo: Text |
Palavras-chave: Gadiforms; Cod; Diversification; Species selection; New species. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-567.pdf |
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| Donati, Giulia Francesca Azzurra; Parravicini, Valeriano; Leprieur, Fabien; Hagen, Oskar; Gaboriau, Theo; Heine, Christian; Kulbicki, Michel; Rolland, Jonathan; Salamin, Nicolas; Albouy, Camille; Pellissier, Loïc. |
| Habitat dynamics interacting with species dispersal abilities could generate gradients in species diversity and prevalence of species traits when the latter are associated with species dispersal potential. Using a process‐based model of diversification constrained by a dispersal parameter, we simulated the interplay between reef habitat dynamics during the past 140 million years and dispersal, shaping lineage diversification history and assemblage composition globally. The emerging patterns from the simulations were compared to current prevalence of species traits related to dispersal for 6315 tropical reef fish species. We found a significant spatial congruence between the prevalence of simulated low dispersal values and areas with a large proportion of... |
| Tipo: Text |
Palavras-chave: Biodiversity; Dispersal; Diversification; Mechanistic models; Reef fish; Traits. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00516/62750/67136.pdf |
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| Lixa,Alice T; Campos,Juliana M; Resende,André L S; Silva,Joice C; Almeida,Maxwell M T B; Aguiar-Menezes,Elen L. |
| Studies show that Apiaceae may provide concentrated vital resources for predator insects, stimulating their abundance, diversity and persistence in agricultural systems, thereby increasing their efficiency as biological control agents. Among the predatory insects, Coccinellidae (Coleoptera) on many different species both as larvae and adults, complementing their diet with pollen and/or nectar. This study aimed to determine the diversity and relative abundance of Coccinellidae species visiting plants of Anethum graveolens (dill), Coriandrum sativum (coriander) and Foeniculum vulgare (sweet fennel) (all Apiaceae), particularly in their blooming seasons, and to evaluate the potential of these aromatic species for providing the resources for survivorship and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ladybeetle; Food source; Conservation biological control; Diversification. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2010000300007 |
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| Ramírez,Claudio C.; Salazar,Marcela; Palma,R. Eduardo; Cordero,Cecilia; Meza-Basso,Luís. |
| Neotropical Rhagoletis species are arranged in four groups: nova,psalida,striatella and ferruginea, which include 18 species. On both sides of the Andes, the evolution of morphological differences among these groups has been suggested to be related to the Andes uplift process. In order to test this hypothesis, a phylogenetic analysis of morphological and molecular data was performed. The results suggest that: 1) Neotropical species of Rhagoletis constitute a separate group from Paleartic and North American species, with the only exception being a member of the striatella group having a certain association with the northern species. 2) Neotropical species seem to form a monophyletic clade, although statistical support for this is weak. 3) The split of South... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Fruit fly; Diversification; Phylogeny; South América. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1519-566X2008000600005 |
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| Bloom,Devin D.; Egan,Joshua P.. |
| ABSTRACT Clupeiformes (herring, sardines, shad, anchovies and allies) are a globally distributed clade with nearly 400 marine, freshwater, and diadromous species. Although best known as filter feeding fishes that form large schools, this group occupies a diverse array of trophic guilds and habitats. Theory suggests that species richness in clades is modulated by ecological limits, which results in diversity-dependent clade growth, a pattern that most clades exhibit. As a trans-marine/freshwater clade that has undergone repeated transitions between marine and freshwaters, Clupeiformes are an excellent system for investigating the interplay between ecological diversity and macroevolutionary dynamics. In this study we review the systematics of Clupeiformes... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Congruence; Comparative methods; Discordance; Diversification; Diversity-dependent. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252018000300201 |
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| Registros recuperados: 76 | |
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