No abstract

The methodology for mapping and for global and cutoff estimation of autocorrelated exploitable resources is presented, based on stationary geostatistical methods. Use and performance of these methods in marine ecology are illustrated with an application to northern shrimp (Pandalus borealis) abundance data, collected in 1989 at 137 stations in the western Gulf of St. Lawrence. Nonstationarity of the biomass data, a proportional increase of the local variance with the local mean, and the presence of outliers all violated the stationarity assumption and strongly hindered the modeling of the spatial structure. Cross-validation tests showed that kriging estimates were better when interpolating within very local neighborhoods using a small number of points. Kriging always performed better than polygonal tessellation. A stratification scheme produced better estimations than the whole-region approach using traditional or relative variograms. The spatial organization of the shrimp biomass was composed of a trend superimposed onto mesoscale patches of 30–50 km in diameter. The area under study contained about 22 000 tonnes of northern shrimp; 70% of this biomass was concentrated in less than 30% of its surface. The spatial information is used to derive guidelines for optimizing future sampling programs.

Although perceived as a benign childhood disease by the general population, varicella may be accompanied by severe complications. Morbidity associated with varicella is one of the elements that must be considered when evaluating the usefulness of varicella vaccine.

Two diploid clones of self-incompatible Solanum chacoense Bitt. with androgenetic ability were tested for anther and leaf disc culture response together with eight of their reciprocal F1 hybrids. Large differences were found among genotypes in frequency of anther induction as well as in the phase of plant regeneration. Anthers harvested in June showed a significantly higher percentage of response (17.5%) at the induction phase than those collected in July (13.8%) or August (12.7%). The lowest induction frequency was observed in May (7.3%). By contrast, plant regeneration from induced anthers did not vary during this time. Genotypic differences were also observed in leaf disc response. The two parental clones and two of their hybrids failed to produce any shoots. Among the remaining genotypes, two had only sporadic occurrence of shoot formation, two gave an intermediate response (15% and 24% of their discs carried shoots), whereas the discs of the two remaining genotypes responded well to culture (68% and 77%). The genetic analysis performed on the reciprocal hybrids revealed that a positive significant correlation existed between anther induction and leaf disc response (Spearman's r = 0.82; p = 0.01). This suggests that, under our conditions, these two aspects of tissue culture might share a common system of genetic control. Estimates of broad sense heritabilities, for leaf disc culture, 83% were obtained and the number of effective factors involved in the control of tissue culture response, indicated a relatively simple genetic control. Finally, considering the potentialities opened by the use of RFLP analysis, it might be possible to find probes that are linked with genes involved in tissue culture competence.

[eng] As a whole, government programmes for farmers have not succeeded in stabilizing prices of agricultural products at a level considered acceptable. Because the federal Agricultural Stabilization Act was not adequate, some provinces, including Quebec, passed their own legislation in this domain. Though aware that administrative price stabilization reduces the signification of market prices, Quebec believes that it must guarantee minimum returns to its farm producers in order that they may enjoy benefits comparable to those available to citizens in general. Through the financial security it ensures, Quebec's act allows for better planning of agricultural operations and proves a valid tool in the development of the agro- food sector. [fre] L'ensemble des programmes gouvernementaux offerts aux producteurs agricoles ne sont pas parvenus à stabiliser les -prix des produits agricoles à un niveau jugé acceptable. Parce que Ha loi fédérale de stabilisation des prix n'était pas adéquate, un certain nombre de provinces, dont le Québec, se sont dotées de leur propre législation en ce domaine. Tout en étant conscient que la stabilisation administrative des prix dimiinue l'importance de ila signification des prix du marché, le Québec croit qu'il doit garantir des revenus minimums à ses producteurs agricoles afin de leur permettre des avantages comparables à ceux accessibles à l'ensemble des citoyens. Par la sécurité financière qu'elle assure, la loi québécoise permet une meilleure planification des opérations agricoles et s'inscrit comme un outil valable de développement du secteur agro- alimentaire.