SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Mécanismes sous-jacents du contrôle bottom-up des populations de sardines dans le Golfe du Lion : enseignements tirés des expériences et de la modélisation

Morvan, Barthelemy; Priour, Daniel; Guede, Zakoua; Bles, G..

The evaluation of the mesh resistance to opening of fishing nets is an important issue in assessing the selectivity of trawls by numerical methods. Sala et al. (2007) proposed a method using a relatively expensive experimental device ensuring the 2D deformation of net sample. De la Prada and Gonzales (2015) proposed a simple uni-axial experimental set-up, which stretches a sample in the transverse direction of the meshes while leaving free its deformation in the normal direction. Both authors (Sala and De la Prada) assumed that the deformation is uniform in the sample. The present study aims at developing a finite element model taking into account the mesh resistance to opening of nets, allowing the simulation of non-uniform deformation. Mechanical...

Tipo: Text

Palavras-chave: Netting; Mesh resistance to opening; Bending stiffness; Experiment; Numerical model.

Ano: 2016

URL: http://archimer.ifremer.fr/doc/00347/45813/49043.pdf

Experimental study of the turbulence intensity effects on marine current turbines behaviour. Part I: One single turbine

Queiros, Quentin.

The Gulf of Lions has faced a sharp drop in the catches of its two main small pelagic exploited species, the sardine Sardina pilchardus and the anchovy Engraulis encrasicolus since the mid-2000s, despite both population abundances remaining high. This situation has been due to a severe decrease in individual body condition and size as a result of both lower growth and the disappearance of the oldest and largest individuals. While overfishing, predation or disease outbreaks have been refuted to explain this situation, one major hypothesis remained to be investigated. A potential shift in sardine and anchovy diet towards smaller planktonic prey indeed suggested bottom-up control as the main driver of these populations in the Gulf of Lions. The first aim of...

Tipo: Text

Palavras-chave: Poissons petits pélagiques; Expérience; Processus bottom-up; Modélisation; Traits d'histoire de vie; Small pelagic fish; Experiment; Bottom-Up processes; Modeling; Life history traits.

Ano: 2019

URL: https://archimer.ifremer.fr/doc/00692/80420/83556.pdf

Three tidal turbines in interaction: An experimental study of turbulence intensity effects on wakes and turbine performance

Mycek, Paul; Gaurier, Benoit; Germain, Gregory; Pinon, Gregory; Rivoalen, Elie.

The ambient turbulence intensity in the upstream flow plays a decisive role in the behaviour of horizontal axis marine current turbines. Experimental trials, run in the IFREMER flume tank in Boulogne-Sur-Mer (France) for two different turbulence intensity rates, namely 3% and 15%, are presented. They show, for the studied turbine configuration, that while the wake of the turbine is deeply influenced by the ambient turbulence conditions, its mean performances turn out to be slightly modified. The presented conclusions are crucial in the view of implanting second generation turbines arrays. In addition, complete and detailed data sets (wake profiles and performance graphs) are made available to the scientific community in order to encourage further...

Tipo: Text

Palavras-chave: Marine current turbine; Performance; Wake; Turbulence; Experiment; Flume tank.

Ano: 2014

URL: http://archimer.ifremer.fr/doc/00175/28647/27171.pdf

Some notes on taxonomic methodology

Gaurier, Benoit; Carlier, Clement; Germain, Gregory; Pinon, Grégory; Rivoalen, Elie.

The development of marine current turbine arrays depends on the understanding of the interaction effects that exist between turbines in close proximity. Moreover, the ambient turbulence intensity also plays a major role in the behaviour of tidal turbines. Thus it is necessary to take ambient turbulence into account when studying interaction effects between several turbines. In order to highlight these interaction effects, experiments have been carried out in the IFREMER flume tank. These experiments focus on interactions between three horizontal axis turbines. This paper presents the experimental results obtained for three configurations with two ambient turbulence intensity rates. The results are presented in terms of turbine wakes and performance. The...

Tipo: Text

Palavras-chave: Marine current turbine; Performance; Wake; Turbulence; Array interaction; Experiment.

Ano: 2020

URL: https://archimer.ifremer.fr/doc/00588/69992/67900.pdf

Naturalis

Hammen, L. van der.

The present paper constitutes an introduction to taxonomic methodology. After an analysis of taxonomic practice, and a brief survey of kinds of attributes, the paper deals with observation, description, comparison, arrangement and classification, hypothesis construction, deduction, model, experiment, abstraction, and synthesis. The methodological aspects of the species-concept and of biological classification are dealt with in two final sections.

Tipo: Article / Letter to the editor

Palavras-chave: Abstraction; Classification; Comparison; Deduction; Description; Experiment; Hypothesis; Methodology; Model; Observation; Species-concept; Synthesis; Systematics; Taxonomy; 42.03; 42.70.

Ano: 1986

URL: http://www.repository.naturalis.nl/record/318283

Experimental assessment of the effects of a Neotropical nocturnal piscivore on juvenile native and invasive fishes

Neotropical Ichthyology

Santos,Alejandra F. G. N.; Alcaraz,Carles; Santos,Luciano N.; Hayashi,Carmino; García-Berthou,Emili.

We experimentally examined the predator-prey relationships between juvenile spotted sorubim Pseudoplastystoma corruscans and young-of-the-year invasive and native fish species of the Paraná River basin, Brazil. Three invasive (peacock bass Cichla piquiti, Nile tilapia Oreochromis niloticus, and channel catfish Ictalurus punctatus) and two native (yellowtail tetra Astyanax altiparanae and streaked prochilod Prochilodus lineatus) fish species were offered as prey to P. corruscans in 300 L aquaria with three habitat complexity treatments (0%, 50% and 100% structure-covered). Prey survival was variable through time and among species (C. piquiti < O. niloticus < A. altiparanae < P. lineatus < I. punctatus), depending largely on species-specific prey...

Tipo: Info:eu-repo/semantics/article

Palavras-chave: Behavior; Experiment; Habitat Complexity; Predator-Prey Interactions; Pseudoplatystoma corruscans.

Ano: 2012

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252012000100016

Do Static Externalities Offset Dynamic Externalities? An Experimental Study of the Exploitation of Substitutable Common-Pool Resources

Giordana, Gaston A.; Montginoul, Marielle; Willinger, Marc.

Overexploitation of coastal aquifers may lead to seawater intrusion, which irreversibly degrades groundwater. The seawater intrusion process may imply that its consequences would not be perceptible until after decades of accumulated overexploitation. In such a dynamic setting, static externalities may enhance the users’ awareness about the resource’s common nature, inducing more conservative individual behaviors. Aiming to evaluate this hypothesis, we experimentally test predictions from a dynamic game of substitutable common-pool resource (CPR) exploitation. The players have to decide whether to use a free private good or to extract from one of two costly CPRs. Our findings do not give substantial support to the initial conjecture. Nevertheless, the...

Tipo: Journal Article

Palavras-chave: Common-pool resources; Substitutable goods; Dynamic externalities; Survival data; Proportional hazard; Experiment; Institutional and Behavioral Economics; Resource /Energy Economics and Policy.

Ano: 2010

URL: http://purl.umn.edu/90842

Constrained School Choice: An Experimental Study

Calsamiglia, Caterina; Haeringer, Guillaume; Klijn, Flip.

The literature on school choice assumes that families can submit a preference list over all the schools they want to be assigned to. However, in many real-life instances families are only allowed to submit a list containing a limited number of schools. Subjects' incentives are drastically affected, as more individuals manipulate their preferentes. Including a safety school in the constrained list explains most manipulations. Competitiveness across schools plays an important role. Constraining choices increases segregation and affects the stability and efficiency of the final allocation. Remarkably, the constraint reduces significantly the proportion of subjects playing a dominated strategy.

The Effects of Penalty Design on Market Performance: Experimental Evidence from an Emissions Trading Scheme with Auctioned Permits

Palavras-chave: School Choice; Matching; Experiment; Gale-Shapley; Top Trading Cycles; Boston Mechanism; Efficiency; Stability; Truncation; Truthtelling; Safety School; Institutional and Behavioral Economics; C72; C78; D78; I20.

Ano: 2009

URL: http://purl.umn.edu/50480

Restiani, Phillia; Betz, Regina.

This paper investigates the behavioural implications of penalty designs on market performance using an experimental method. Three penalty types and two penalty levels are enforced in a laboratory permit market with auctioning, including the Australian Carbon Pollution Reduction Scheme proposed design of tying the penalty rate to the auction price. Compliance strategies are limited to undertaking irreversible abatement investment decisions or buying permits. We aim to assess how penalty design under the presence of subjects‟ risk preferences might affect compliance incentives, permit price discovery, and efficiency. In contrast to theory, we find that penalty levels serve as a focal point that indicates compliance costs and affects compliance strategies....

Tipo: Report

Palavras-chave: Emissions trading; Penalty design; Experiment; Auction; Irreversible investment; Abatement; Compliance; Environmental Economics and Policy; Resource /Energy Economics and Policy.

Ano: 2010

URL: http://purl.umn.edu/107586

Myopic or Farsighted? An Experiment on Network Formation

Mantovani, Marco; Kirchsteiger, Georg; Mauleon, Ana; Vannetelbosch, Vincent.

Pairwise stability (Jackson and Wolinsky, 1996) is the standard stability concept in network formation. It assumes myopic behavior of the agents in the sense that they do not forecast how others might react to their actions. Assuming that agents are farsighted, related stability concepts have been proposed. We design a simple network formation experiment to test these theories. Our results provide support for farsighted stability and strongly reject the idea of myopic behavior.

Consumer Preferences for Olive Oil in Tirana, Albania

Palavras-chave: Network Formation; Experiment; Myopic and Farsighted Stability; Environmental Economics and Policy; D85; C91; C92.

Ano: 2011

URL: http://purl.umn.edu/108256

Chan-Halbrendt, Catherine; Zhllima, Edvin; Sisior, Gwendalyn; Imami, Drini; Leonetti, Luciano.

Increase in urban middle income consumers along with consolidation of the retail sector has created changes in olive oil consumption preferences in Albania. The objective of this study is to inform stakeholders in the olive oil industry about consumer preferences. A Conjoint Choice Experiment (CCE) was used to design the survey and latent class approach used to analyze the data. The results show a strong preference for domestic olive oil and small niche markets that cater to specific consumers. The study also shows a gap between preference and reality that needs to be addressed by the stakeholders in the olive oil industry.

Tipo: Journal Article

Palavras-chave: Olive oil; Albania; Latent Class; Consumer preference; Conjoint choice; Experiment; Consumer/Household Economics; Crop Production/Industries; Research Methods/ Statistical Methods.

Ano: 2010

URL: http://purl.umn.edu/93559

Buying Time: Real and Hypothetical Offers

Smith, V. Kerry; Mansfield, Carol.

This paper provides the results of a field test of contingent valuation estimates within a willingness to accept framework. Using dichotomous choice questions in telephone mail-telephone interviews, we compare responses to real and hypothetical offers to survey respondents for the opportunity to spend time in a second set of interviews on an undisclosed topic. Five hundred and forty people were randomly split between the real and hypothetical treatments. Our findings indicate no significant differences between people's choices with real and hypothetical offers. Choice models indicate the size of the offer and income were significant determinants of respondents' decisions, and these models were not significantly different between real and hypothetical offers.

Palavras-chave: Contingent value; Real and hypothetical offer; Willingness to accept; Experiment; Institutional and Behavioral Economics; C93; D12; Q2.

Ano: 1996

URL: http://purl.umn.edu/10719

Strategic Self-Ignorance

Thunstrom, Linda; Nordstrom, Jonas; Shogren, Jason F.; Ehmke, Mariah D..

This paper analyzes if people use ignorance as an excuse to pursue immediate gratification, at the expense of future wellbeing, a behavior we label ‘strategic self-ignorance’. In a theoretical model we show that present-biased individuals benefit from choosing ignorance of the potentially negative impact of present consumption, and that ignorance leads to over consumption of harmful goods. In an experiment we empirically test for strategic self-ignorance. The experiment entails prepared meals, for which subjects may be familiar with the taste (immediate utility) but are uninformed of the calorie content (potential harm to future health). Subjects are offered costless information on the calorie content of the meal alternatives. A majority of subjects (58...

Tipo: Presentation

Palavras-chave: Strategic ignorance; Harmful consumption; Experiment; Demand and Price Analysis; Food Consumption/Nutrition/Food Safety; Health Economics and Policy.

Ano: 2012

URL: http://purl.umn.edu/123949

Effects of Natural Shocks on Risk Behavior. Experimental Evidence from Cameroon

Balgah, Roland Azibo; Buchenrieder, Gertrud.

Increasing occurrence of devastating natural shocks has stimulated research interest in the economics of natural disasters. Much of this scholarly work concentrates on effects of shocks on poverty, risk and vulnerability, and very little on understanding the effects of natural shocks on risk behavior. Referring to a 25 year-old disaster, we use unique survey data and experiment results from two disaster affected communities in rural Cameroon to test two hypotheses: (1) Natural shocks affect long term risk behavior; and (2) self-relocation into risk-prone areas is an explicit demonstration of risk taking. The results reveal differentiated risk behavior in self-relocated and state-resettled households, with the former taking higher risks compared to...

Tipo: Conference Paper or Presentation

Palavras-chave: Shocks; Risk behavior; Experiment; Cameroon; Risk and Uncertainty.

Ano: 2011

URL: http://purl.umn.edu/114215

Polarized Preferences In Homegrown Value Auctions

Hurley, Terrance M.; Yue, Chengyan; Anderson, Neil O..

Incentive compatible auction experiments, often referred to as homegrown value auctions, have become a popular tool for exploring how controversial product attributes and knowledge of these attributes affect consumer willingness to pay. A common observation in these experiments is a prevalence of zero bids and bimodal bid distributions. One possible explanation is that individuals have polarized preferences: find all products with a particular attribute desirable (positive polarization) or undesirable (negative polarization). The purpose of this paper is to explore three questions. Do polarized preferences exist? If they do exist, can they be identified? If they can be identified, does their identification provide useful information? To answer these...

Tipo: Conference Paper or Presentation

Palavras-chave: Experiment; Auctions; Polarized Preferences; Invasive Plants; Homegrown Values; Demand and Price Analysis; Environmental Economics and Policy; Research Methods/ Statistical Methods; D01; C18; C19; Q13.

Ano: 2011

URL: http://purl.umn.edu/103596

Zahlungsbereitschaften für Frischmilch aus der Region: Ergebnisse einer Kontingenten Bewertung und einer experimentellen Untersuchung

Schroeder, Carsten; Burchardi, Henrike; Thiele, Holger D..

In this paper we present the results of a contingent valuation study and an experimental approach to estimating the willingness to pay for fresh milk produced in the consumer's own region. In contrast to the fictitious contingent valuation study, responses in the experimental investigation are connected with real demand decisions and real financial payoffs in an incentive-compatible way. The experimental setup allows to quantify the bias in stated willingness to pay that results from the contingent valuation’s hypothetical character. In essence, the data suggest that there exists a considerable demand for milk from the consumers` home region. Yet, significantly less demand is found in the experimental investigation. At the same time, subjects accept...

Tipo: Journal Article

Palavras-chave: Willingness-to-pay; Contingent valuation; Experiment; Incentive compatibility; Food of the own region; Demand and Price Analysis; Marketing.

Ano: 2005

URL: http://purl.umn.edu/97323

In Search of Stars: Network Formation among Heterogeneous Agents

Ule, Aljaz; Goeree, Jacob K.; Riedl, Arno.

This paper reports results from a laboratory experiment on network formation among heterogeneous agents. The experimental design extends the Bala-Goyal (2000) model of network formation with decay and two-way flow of benefits by allowing for agents with lower linking costs or higher benefits to others. Furthermore, agents' types may be common knowledge or private information. In all treatments, the (efficient) equilibrium network has a "star" structure. With homogeneous agents, equilibrium predictions fail completely. In contrast, with heterogeneous agents stars frequently occur, often with the high-value or low-cost agent in the center. Stars are not born but rather develop: with a high-value agent, the network's centrality, stability, and efficiency all...

Auction Experiments and Simulations of Milk Quota Exchanges

Palavras-chave: Network Formation; Experiment; Heterogeneity; Private Information; Institutional and Behavioral Economics; C72; C92; D82; D85.

Ano: 2007

URL: http://purl.umn.edu/9099