2,138 research outputs found
Managerial Competencies for Organizational Flexibility:The Luxury Goods Industry between Tradition and Postmodernism
Luxury goods are selling well and the growth of the industry has barely been slowed down by the Asian crisis (Les Echos, 04-30-1998, 09-25-1998; Le Figaro, 04-06-1998; Financial Times, 04-24-1999). As in many other growth markets, though, good results are coming together with a fair amount of turmoil. Many changes are redefining environmental conditions and new challenges are creating significant turbulence for players in the industry at a global level (Ecole de Paris, 1998; Womanâs Wear Daily, 02-10-1998; LibĂ©ration, 03-06/07-1999). Our question in this paper is whether, in the face of such global trends, luxury goods companies have reacted and attempted to adapt. We are interested by changes and evolutions with an impact on organizational structures but also by the potential redefinition of managerial roles and competencies. [First paragraph
Query Rewriting with Disjunctive Existential Rules and Mappings
We consider the issue of answering unions of conjunctive queries (UCQs) with
disjunctive existential rules and mappings. While this issue has already been
well studied from a chase perspective, query rewriting within UCQs has hardly
been addressed yet. We first propose a sound and complete query rewriting
operator, which has the advantage of establishing a tight relationship between
a chase step and a rewriting step. The associated breadth-first query rewriting
algorithm outputs a minimal UCQ-rewriting when one exists. Second, we show that
for any ``truly disjunctive'' nonrecursive rule, there exists a conjunctive
query that has no UCQ-rewriting. It follows that the notion of finite
unification sets (fus), which denotes sets of existential rules such that any
UCQ admits a UCQ-rewriting, seems to have little relevance in this setting.
Finally, turning our attention to mappings, we show that the problem of
determining whether a UCQ admits a UCQ-rewriting through a disjunctive mapping
is undecidable. We conclude with a number of open problems.Comment: This report contains the paper accepted at KR 2023 and an appendix
with full proofs. 24 page
Tungsten-enhanced growth of Methanosphaera stadtmanae
Background: The methanogenic Archaea Methanosphaera stadtmanae has been detected in the human gut microbiota by both culture and culture-independent methods. Its growth reaches an exponential phase after 5 to 7-day culture in medium 322 (10% vol). Our recent successful isolation of Methanomassiliicoccus luminyensis, a tungstate-selenite-requiring Archaea sharing similar metabolism characteristics with M. stadtmanae prompted us to study the effects of tungsten and selenium on M. stadtmanae growth.Findings: Addition of 0.2 mg/L sodium tungstate to medium 322 yielded, 48 hours after inoculation, a growth rate equivalent to that obtained after 6 days with control culture as measured by methane monitoring and optical density measurement. Addition of 50 ÎŒg/mL sodium selenate had no effect on M. stadtmanae growth. Quantitative real-time PCRs targeting the M. stadtmanae 16S rRNA confirmed these data.Conclusions: These data provide new information regarding the poorly known nutritional requirements of the human gut colonizing organisms M. stadtmanae. Adding sodium tungstate to basal medium may facilitate phenotypic characterization of this organism and additionally aid the isolation of new Archaeafrom complex host microbiota
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