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| Registros recuperados: 45 | |
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| Peña-Gómez,Francisco T; Bustamante,Ramiro O. |
| In this study, we compared demographic responses of Eschscholzia californica populations located at different altitude, under the basic assumption that altitudinal gradients impose environmental limitation to the spread at the upper edge of the gradient. We detected significant differences among populations either in terms of life history attributes and the finite rate of increase. In general, coastal population expressed higher finite population rates than mountain populations, although these differences were not statistically significant. Mountain populations (Corral Quemado and Farellones) expressed a finite population rate not significant different of 1. These result suggest that at the upper front of invasion the species is in a demographic... |
| Tipo: Journal article |
Palavras-chave: Populations; Invasions; Heterogeneity; Demographic matrix. |
| Ano: 2012 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432012000100011 |
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| Siddiqui, Numair A.; Ramkumar, Mu.; Rahman, Abdul Hadi A.; Mathew, Manoj J.; Santosh, M.; Sum, Chow W.; Menier, David. |
| Advances in photogrammetry have eased the acquisition of high-resolution digital information from outcrops, enabling faster, non-destructive data capturing and improved reservoir modeling. Geocellularmodels for flow dynamics with in the virtual outcrop in siliciclastic deposits at different sets of sandstone facies architecture remain, however, a challenge. Digital maps of bedding, lithological contrast, spatial-temporal variations of bedding and permeability characteristics make it more easy to understand flow tortuosity in a particular architecture. An ability to precisely model these properties can improve reservoir characterization and flow modeling at different scales. Here we demonstrate the construction of realistic 2D sandstone facies based models... |
| Tipo: Text |
Palavras-chave: Siliciclastic sandstone facies; Connectivity; Heterogeneity; Digital outcrop model; Flow dynamics. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00637/74937/76048.pdf |
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| Raimonet, Melanie; Ragueneau, Olivier; Andrieux Loyer, Francoise; Philippon, Xavier; Kerouel, Roger; Le Goff, Manon; Memery, Laurent. |
| The high heterogeneity of silica cycling in coastal margins and the lack of silica data (compared to nitrogen and phosphorus) prevent the estimation of global silica retention in estuaries. In this study, the spatial and temporal variability of porewater silicic acid (Si(OH)4) profiles e that integrate benthic transport and reaction processes e was investigated at different spatial (metre, longitudinal and crosssection, intra-estuary) and temporal (tidal, seasonal) scales in two macrotidal estuaries, very close geographically but essentially differing in their shape. Studying the spatial and temporal variability of Si(OH)4 concentrations in porewaters provided evidence for the importance of transport processes, e.g. bio-irrigation, tidal pumping,... |
| Tipo: Text |
Palavras-chave: Heterogeneity; Season; Silicate; Sediment; Land-sea interface; Upscaling. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00124/23529/22370.pdf |
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| Benhaim, David; Pean, Samuel; Brisset, Blandine; Leguay, Didier; Begout, Marie-laure; Chatain, Beatrice. |
| This study aims to test the influence of size grading on self-feeding behaviour, social structure (measured by the percentage of triggering acts per individual), growth performances, and blood physiological variables of individually passive integrated transponder (PIT)-tagged sea bass juveniles, using a computerized on-demand feeding system coupled with a PIT tag monitoring device. Three consecutive periods of 27 days each were compared: a first period (P1) before grading (6 tanks of 100 fish; 40.2 +/- 8.9 g) followed by a second period (P2) after grading. The protocol applied aimed to create two groups of fish of similar mean weight but with either a low or a high coefficient of variation of weight (CV(w)) corresponding to an imposed difference in social... |
| Tipo: Text |
Palavras-chave: Feeding behaviour; Self feeder; Triggering activity; Heterogeneity; Growth; Grading. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00057/16858/14340.pdf |
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| Dillen, Koen; Demont, Matty; Tollens, Eric. |
| After more than a decade of GM crops, literature reports farmers and consumers can gain significantly from the technology, despite the intellectual property rights assigned to the innovator. In this paper we assess the effect of heterogeneity on this distribution of benefits. A two dimensional framework is created to assess the ex ante benefits of an innovation. Given this setting and the scarce data often available, a parametric modelling approach is taken. The two dimensions of heterogeneity, spatial and temporal, are explicitly modelled as they have a different importance for different technologies. Using this framework we can simulate different corporate pricing strategies and evaluate the benefits generated under changing heterogeneity. The framework... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Heterogeneity; Parametric modelling; Ex ante; Research and Development/Tech Change/Emerging Technologies. |
| Ano: 2008 |
URL: http://purl.umn.edu/43945 |
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| Eija, Pouta; Sami, Myyra; Kyosti, Pietola. |
| Land improvements with long pay-back periods are often delayed on leased agricultural land, resulting in social costs through land degradation, decreased land productivity and environmental problems. An important question is thus how landowners would respond to regulations and mandates concerning land improvements. Based on a landowner survey, we analyse landowner choices under certain land improvement regulations, using the currently dominant choice of leasing land for agricultural use as the benchmark. The results indicated that land leasing will continue to increase in the future, but if the landowner mandate to co-finance costly land improvements is increased, landowners are predicted to respond significantly to these mandates and search for other land... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Contingent behaviour; Latent class model; Landlord; Land use; Heterogeneity; Land Economics/Use; Q15; Q24; Q28. |
| Ano: 2011 |
URL: http://purl.umn.edu/114770 |
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| Dubois, Pierre; Vukina, Tomislav. |
| The objective of this paper is to develop an analytical framework for estimation of the parameters of a structural model of an incentive contract under moral hazard, taking into account agents heterogeneity in preferences. We show that allowing the principal to strategically distribute the production inputs across heterogenous agents as part of the contract design, the principal is able to change what appears to be a uniform contract into individualized contracts tailored to fit agents' preferences or characteristics. Using micro level data on swine production contract settlements, we find that contracting farmers are heterogenous with respect to their risk aversion and that this heterogeneity affects the principal's allocation of production inputs across... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Agency Contracts; Optimal Incentives; Moral Hazard; Risk Aversion; Heterogeneity; Production Economics; D82; L24; Q12; K32; L51. |
| Ano: 2006 |
URL: http://purl.umn.edu/25568 |
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| Bignebat, Celine; Rouviere, Elodie. |
| Collective quality management systems are well known instruments to manage the quality and/or the safety of foodstuffs. They can be considered as voluntary approaches to food safety. In environmental economics some empirical studies emphasize that firms entering into a collective voluntary program behave differently because their motivations differ. To the best of our knowledge, there is no formal discussion on the effectiveness of a collective voluntary program in which firms adopt different behaviour once they entered the program. Starting from this two strand of literature, we extend the analytical framework of collective voluntary approaches considering heterogeneous firms and applying it to food safety issues. We show that according to firms... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Voluntary Approaches; Food Safety; Collective Action; Heterogeneity; Food Consumption/Nutrition/Food Safety; Q18; L51; L81. |
| Ano: 2007 |
URL: http://purl.umn.edu/9441 |
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| Lapple, Doris; Kelley, Hugh. |
| Whilst the adoption of agricultural techniques has received considerable attention in the literature, the ability and willingness of potential adopters to change their current farming system is often overlooked. This paper is concerned with the intention of conventional farmers to convert to organic farming by using the social-psychology theory of planned behaviour. Drivers and barriers of conversion to organic farming are identified by applying a belief based concept, which is confirmed using principal component analysis. In addition, accounting for heterogeneity regarding farmers‟ environmental attitudes masks considerable differences, notably at intention, attitudes and control perceptions. Overall, results reveal that conversion is indeed affected by... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Organic farming; Theory of planned behaviour; Principal component analysis; Heterogeneity; Production Economics. |
| Ano: 2010 |
URL: http://purl.umn.edu/91949 |
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| Persitz, Dotan. |
| The heterogeneous connections model is a generalization of the homogeneous connections model of Jackson and Wolinsky (1996) in which the intrinsic value of each connection is set by a discrete, positive and symmetric function that depends solely on the types of the two end agents. Core periphery networks are defined as networks in which the agents' set can be partitioned into two subsets, one in which the members are completely connected among themselves and the other where there are no internal links. A two-type society is defined as "power based" if both types of agents prefer to connect to one of the types over the other, controlling for path length. An exhaustive analysis shows that core periphery networks, in which the "preferred" types are in the... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Network Formation; Heterogeneity; Pairwise Stability; Institutional and Behavioral Economics; D85; L14. |
| Ano: 2009 |
URL: http://purl.umn.edu/52338 |
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| Beville, Stephen; Kerr, Geoffrey N.. |
| Recreational anglers are known to seek different types of experiences in different settings. Such preference and behavioural diversity has important management implications. Research methods which assume only a limited degree of preference heterogeneity and impose rigid substitution patterns can impair understanding of individual’s unique decision process and lead to misguided management and policy recommendations. This paper reports results from an internet-based stated preference survey of recreational trout anglers in the North Canterbury Region of New Zealand. A mixed logit model, which simultaneously specifies random parameters plus error components, is used to capture the extent of random preference heterogeneity in systematic utility along with... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Random utility model; Latent class; Mixed logit; Error component; Heterogeneity; Recreational angler. |
| Ano: 2009 |
URL: http://purl.umn.edu/48038 |
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| Registros recuperados: 45 | |
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