110 resultados para Abelian groups.
Resumo:
The qualitative aspects of the Contingent Valuation Method (CVM) are largely ignored by (environmental) economists. This paper aims to instigate a discussion on (a) the usefulness of qualitative data to the contingent valuation process in general; and (b) the use and applicability of the focus group method in particular. We consider the range and uses of focus groups within the CVM and highlight problems with their analysis that have, to date, largely been ignored. A potential solution to circumvent the problem of non-independence of group data is suggested. While there are several distinct and worthwhile uses for qualitative data, focus groups should not automatically be taken as the only or best method to produce these insights even though they are the major one considered in this article. (C) 1999 Elsevier Science B.V. All rights reserved.
Resumo:
The O-specific lipopolysaccharide side chains of Escherichia coli O7 and Shigella boydii type 12 possess similar but not identical chemical structures. We investigated the genetic relatedness between the O-specific side chain genes in members of these two species. Examination of outer membrane protein and lipopolysaccharide (LPS) banding patterns demonstrated that five strains which had been identified as S. boydii type 12 fell into two clonal groups, SB1 and SB2. Hybridizations with O7-specific radiolabeled probes derived from the chromosomal DNA of an E. coli O7 strain detected identical fragments among the three SB1 strains of S. boydii type 12 and the two E. coli O7 reference isolates. The two other S. boydii type 12 strains, which belonged to the SB2 clone, did not show homologies with the O7 probe under high-stringency conditions of hybridization. The homology between the O7 and type 12 LPS gene regions from the SB1 strains was further confirmed by the construction of O-specific side chain-deficient mutations in these strains by homologous recombination of a suicide plasmid containing O7-specific DNA sequences. Immunoblot experiments with O7 antiserum gave a weak cross-reaction with LPS purified from the SB2 strains but a very strong cross-reaction with the LPS from SB1 isolates. Antiserum raised to one of the SB2 strains cross-reacted only with S. boydii type 12 LPS from the SB1 clone but failed to react with O7 LPS.
Resumo:
The incidence of the aerobactin system and the genetic location of aerobactin genes were investigated in Escherichia coli K1 neonatal isolates belonging to different clonal groups. A functional aerobactin system was found in all members of the O7 MP3, O1 MP5, O1 MP9, and O18 MP9 clonal groups examined and also in K1 strains having O6, O16, and O75 lipopolysaccharide types, which are less frequently associated with neonatal infections. In contrast, the aerobactin system was not detected in strains from the O18 MP6 clone. The combined results of plasmid and colony hybridization experiments showed that the aerobactin genes were located on the chromosome in the majority (75%) of the aerobactin-producing K1 isolates, the genetic location of the aerobactin genes was closely correlated with the outer membrane protein profile rather than the O lipopolysaccharide type, the K1 strains harboring a chromosome-mediated aerobactin system did not possess colicin V genes, and five of six K1 isolates possessing a plasmid-borne aerobactin system contained colicin V genes which were located on the same plasmids carrying the aerobactin genes. The comparison of hemolysin production with possession of the aerobactin system in virulent clones of E. coli K1 strains showed that all of the aerobactin-producing strains from the O18 MP9 and O7 MP3 clonal groups did not synthesize hemolysin, whereas 11 of 12 aerobactin-nonproducing O18 MP6 isolates were hemolytic. Of the K1 strains examined, 92.5% possessed either the aerobactin system or the ability to produce hemolysin or both.
Resumo:
In this article we take advantage of the availability of European Union Statistics on Income and Living Conditions (EU-SILC) data to address both weak and strong versions of the Europeanization of reference groups thesis. The former proposes that common standards of evaluation emerge as a consequence of knowledge of conditions in other societies. The latter argues that people increasingly perceive themselves as part of a larger European stratification system. Our analysis leads us to reject both versions of the thesis. Material deprivation rather than having a uniform effect is highly dependent on national context. If a process of convergence is underway, it is one that as yet has had a limited impact. In circumstances where the Europeanization of inequality is raising issues relating to both national and transnational forms of legitimacy, it is important to understand that there is no necessary relationship between such Europeanization and the Europeanization of reference groups.