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| Registros recuperados: 25 | |
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| Bacher, Cedric; Deslous-paoli, Jean-marc; Heral, Maurice; Prou, Jean. |
| The expansion of shellfish culture businesses (oysters, mussels, clams...) gives way to a competition for the use of limited food resources, especially in the Marennes-Oléron basin where water circulation is slow. Increasing the amount of cultivated molluscs leads, from a biological point of view, to:- a drop in growth performances- a rise in chronic mortalities, higher and higher, due to a weakness in the physiological state with a lack of stocks which would have compensated the habitat seasonal shortages (end of winter, etc...)- a greater weakness to diseases, linked to a deficient physiological state and a density rise which increases the proximity rate and thus, parasite propagation speed.For these primary reasons, and for the future of oyster culture,... |
| Tipo: Text |
Palavras-chave: Modélisation; Estimation; Echantillonnage; Mollusques; Marennes Oléron; Evaluation stocks. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/1986/rapport-3841.PDF |
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| Beliaeff, Benoit; Burgeot, Thierry. |
| Activity of 7-ethoxyresorufin-O-deethylase (EROD) in fish is certainly the best-studied biomarker of exposure applied in the field to evaluate biological effects of contamination in the marine environment. Since 1991, a feasibility study for a monitoring network using this biomarker of exposure has been conducted along French coasts. Using data obtained during several cruises, this study aims to determine the number of fish required to detect a given difference between 2 mean EROD activities, i.e. to achieve an a priori fixed statistical power (l-beta) given significance level (alpha), variance estimations and projected ratio of unequal sample sizes (k). Mean EROD activity and standard error were estimated at each of 82 sampling stations. The... |
| Tipo: Text |
Palavras-chave: Biomonitoring; Estimation; EROD activity; Statistical power; Sample size; Sampling design. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44787/44483.pdf |
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| Huthnance, John M.; Coelho, Henrique; Griffiths, Colin R.; Knight, Philip J.; Rees, Andrew P.; Sinha, Bablu; Vangriesheim, Annick; White, Martin; Chatwin, Paul G.. |
| The physical context for ocean margin exchange at Goban Spur is described. Observations adjacent to, prior to and during the Ocean Margin EXchange (OMEX) project of 1993-1996 are used. They include currents measured on moorings, drogued-buoy tracks; temperature and other data from CTD profiles, especially as indicators of vertical mixing; evidence from models, particularly for turbulence causing vertical mixing. These data are combined in estimates of (seasonally dependent) mean flow, tidal currents, other current variability, exchange and mixing over the main cross-slope section studied in OMEX and in nearby and contrasted locations (aided by the use of earlier and adjacent measurements). Causative physical processes are discussed: potentially northward... |
| Tipo: Text |
Palavras-chave: Estimation; Physical process; Tidal current; Mixing; Ocean margin exchange; Physical oceanography. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-740.pdf |
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| Heral, Maurice; Goulletquer, Philippe; Razet, Daniel; Prou, Jean; Ravail, Brigitte; Maestrini, Serge. |
| Different sampling strategies have been tested for estimation of phytoplanktonic biomasses in a bay submitted to estuarine conditions and high velocity of currents. Daily variations showed that for a precision of 5% of the daily mean, it is necessary to sample with a 1 hour and a half time scale. Systematic sampling appears to be more preceise than the random sampling. A sampling during 35 days at low tide and at high tide, during the phytoplanktonic bloom, showed the large variability between the days. A precision of 30% of the mean biomass of the month is obtained with a 8 days time scale. Comparison between tidal cycle sampling (10% of precision) with a punctual sample in the middle of the day did not show large differences. As the main variability is... |
| Tipo: Text |
Palavras-chave: Marennes Oleron; Phytoplanktonic biomasses; Estimation. |
| Ano: 1988 |
URL: http://archimer.ifremer.fr/doc/1988/acte-2877.pdf |
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| Bacher, Cedric; Baud, Jean-pierre; Bodoy, Alain; Deslous-paoli, Jean-marc; Dreno, Jean-paul; Heral, Maurice; Maurer, Daniele; Prou, Jean. |
| An assessment of the reared stocks of the Pacific oyster (Crassostrea gigas ) has been recently conducted on the major French areas of molluscs culture. The methodology proposed included both estimates of densities obtained by subsampling in the field, and aerial photographs which covered the cultivated, intertidal area. The size and the number of samples were designed to reach a precision of 10% on the final assessment in each area. The field work consisted in weighing and counting the oyster in unit areas of 0.5 m2 for the bottom culture or in trays or bags, for the off bottom technique. These results give a better knowledge of the technique evolution and of the general structures in the cultivated areas. |
| Tipo: Text |
Palavras-chave: Modeling; Estimation; Stocks; Crassostrea gigas; Oysters. |
| Ano: 1986 |
URL: http://archimer.ifremer.fr/doc/1986/acte-2864.pdf |
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| Bordeyne, François; Robert, Stephane; Le Moine, Olivier; Leaute, Jean-pierre. |
| On French coast, Manila clam is a bivalve subject of a large activity recreational and professional hand harvest. Two species are represented in France, European Manila clam Ruditapes decussatus (native) and Japanese Manila clam Ruditapes philippinarum (introduced). Predominance of this last species (more than 90 % of number and biomass), earn them the status of invasive species. Contrary to Arcachon bay, Pont l’Abbé River or Morbihan bay, an estimation campaign of Manila clams stock on Marennes-Oléron bay had never been carried out. The objective of this study: estimate, in number and biomass, the Manila clams stock of two areas. The first affect recreational hand harvest, on Saint-Trojan shore (0.8 km²) whereas the second scopes professional hand... |
| Tipo: Text |
Palavras-chave: Palourde; Ruditapes philippinarum; Ruditapes decussatus; Estimation; Stock; Marennes–Oléron.; Manilla clam; Ruditapes philippinarum; Ruditapes decussatus; Estimation; Stock; Marennes–Oleron. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00415/52621/53459.pdf |
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| Chauvaud, Laurent; Lorrain, Anne; Dunbar, Robert; Paulet, Yves; Thouzeau, Gérard; Jean, Frédéric; Guarini, Jean-marc; Mucciarone, David. |
| We investigate the environmental and biological controls on oxygen isotope ratios in the shells of modern Pecten maximus bivalves collected alive in the Bay of Brest (France). Seasonal delta(18)O profiles, obtained by drilling the daily calcite ridges deposited at the surface of the left valve, were compared with in situ measurements of temperature and salinity. We show that P. maximus delta(18)O values accurately track seasonal variations in bottom water temperature. Shell growth rate has no significant effect on shell delta(18)O values. Our study demonstrates that daily variations in water temperature can be reconstructed within about 0.5 degrees C. Temperatures estimated with the paleotemperature equation established in this study were compared with... |
| Tipo: Text |
Palavras-chave: Pecten Maximus; Brittany; Paleoenvironment; Estimation; Daily varition; Water temperature; Isotope; Calcite; Shell; Ëecten maximus; Paleotempérature; Variation saisonnière; Température eau; Strie croissance; Isotope; Coquille. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-643.pdf |
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| Jouffre, D.; Borges, M.; Bundy, A.; Coll, M.; Diallo, I.; Fulton, E.A.; Guitton, J.; Labrosse, P.; Mohamed Abdellahi, K.O.; Masumbuko, D.; Thiaro, D.. |
| Tipo: Journal Contribution |
Palavras-chave: Scientific research; Estimation; Trawling; Ices. |
| Ano: 2010 |
URL: http://hdl.handle.net/1834/4985 |
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| Preckel, Paul V.. |
| Mathematical measures of entropy as defined by Shannon (1948) and Kullback and Leibler (1951) are currently in vogue in the field of econometrics, primarily due to the comprehensive work by Golan, Judge, and Miller (1996). In this paper, an alternative interpretation of the entropy measure as a penalty function over deviations is presented. Using this interpretation, a number of parallels are drawn with least squares estimators, and it is demonstrated that, with a minor modification of the traditional least squares estimator, both approaches may be applied to the general linear model. The advantages and disadvantages of each approach are discussed, and a philosophical approach to the selection of estimation technique is suggested. |
| Tipo: Working or Discussion Paper |
Palavras-chave: Entropy; Econometrics; Penalty functions; Estimation; Research Methods/ Statistical Methods. |
| Ano: 1998 |
URL: http://purl.umn.edu/28625 |
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| Kikuchi, Masao; Weligamage, Parakrama; Barker, Randolph; Samad, Madar; Kono, Hiroichi; Somaratne, H.M.. |
| The use of shallow wells, equipped with small pumps, to lift groundwater has spread rapidly in many agricultural regions of tropical monsoonal Asia. In Sri Lanka, the rapid and pervasive invasion of agro-wells and pumps drew the attention of policymakers and researchers, but many questions were left unanswered due to lack of research in the area. This study aims to fill this gap in knowledge, based on observations and data obtained in field surveys conducted in major and minor irrigation schemes in the dry zone of Sri Lanka. This report gives the key findings of this study into the pattern, extent and causes of the spread and use of agro-wells and pumps in traditional villages and irrigated settlement schemes. It investigates farmer investments in... |
| Tipo: Report |
Palavras-chave: Wells; Construction technology; Pumps; Arid zones; Investment; Irrigation systems; Irrigation programs; Rice; Estimation; Agribusiness; Agricultural Finance; Crop Production/Industries; Financial Economics; Marketing; Public Economics. |
| Ano: 2003 |
URL: http://purl.umn.edu/44558 |
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| Niemi, Jyrki S.; Huan-Niemi, Ellen. |
| China's accession to the WTO means significant increases in export opportunities for China's trading partners. This study attempts to identify and measure quantitatively the effects of changing economic environment and trade policies on China's agricultural imports from the European Union (EU). The approach is to estimate demand functions for China's agri-food imports from the EU using semi-annual data from 1980 to 2000. The demand functions are used to measure the impacts of relative-price and trade policy changes on EU agricultural exports to China. The results suggest that in China, there is a relatively strong demand response for agrifood imports to changes in income and prices. Furthermore, the results indicate that relative-price variations affect... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: China; WTO; Agricultural trade; Tariffs; Demand functions; Estimation; International Relations/Trade. |
| Ano: 2002 |
URL: http://purl.umn.edu/24839 |
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| Pizaia, Marcia Goncalves; Alves, Rozane. |
| Partindo-se da tarifa de água cobrada dos consumidores residenciais de baixa renda no município de Cambe, Estado do Paraná, considerando-se o esquema de tarifas em bloco praticado pelas companhias de água, da renda familiar, do número de habitantes por domicílio, e dos custos marginais de produção de água, este estudo objetiva estimar, através da função demanda residencial por água, quanto os aumentos efetuados nas tarifas cobradas aos usuários residenciais de renda baixa influenciam na quantidade de água demandada por esses usuários. Concluiu-se que a demanda residencial por água explica, para a classe analisada, a hipótese que deveria ser provada. Ou seja, mudanças efetuadas nas tarifas cobradas aos usuários, afetam as quantidades de água demandadas por... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Estimação; Função demanda; Baixa renda; Estimation; Demand function; Resource /Energy Economics and Policy. |
| Ano: 2008 |
URL: http://purl.umn.edu/108928 |
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| Registros recuperados: 25 | |
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