Biominerals - source and inspiration for novel advanced materials

Biomineralization seems an odd sort of word. How can you combine biology and minerals? However, a quick look around brings to light many familiar objects that are examples of biominerals. Most dramatic are the coral reefs and sea shells of the marine environment (calcium carbonate) and human bone and teeth (calcium hydroxyapatite) but there are many other examples. In the past 10 years, an increasing number of biominerals has been reported (Table 1). Interest in the biological and chemical processes that lead to biomineralization, howeyer, has only developed rather recently. Early observations were made by paleontologists who were interested in the preservation, through geological time, of the hard parts of organisms such as shells and skeletons but only in 1989 did the field really come of age with the almost simultaneous publication of three monographs covering current knowledge of the biological, biochemical, chemical and taxonomic aspects of biomineralization (Mann et al. 1989; Lowenstam & Weiner 1989; Simkiss & Wilbur 1989)

Drivers of Demand for Imported Horticultural Commodities: A Cross-Country Comparison

International trade of horticultural commodities is increasingly important in many regions of the world, yet relatively little research has studied import patterns of key horticultural crops. Using data between 1991 and 2005, we find that import demand for horticultural commodities in developed countries has been driven primarily by prices and the level of trade openness while income and diet considerations were more important in emerging countries. Furthermore, our results show that the determinants of import demand differed across the selected crops, and therefore information can be lost if data for horticultural commodities are aggregated.Emerging markets, Horticultural commodities, Import demand, International trade, International Relations/Trade, Marketing, Q10, Q13, Q17,

Import Demand for Horticultural Commodities in Developed and Emerging Countries

International trade of horticultural commodities is increasingly important in many regions of the world, yet import patterns of key horticultural crops are understudied in the agricultural economics literature. Using data between 1991 and 2005, we estimate the drivers of per capita import demand for six of the most highly traded horticultural commodities. The own price elasticity estimates were negative in all import demand models and, in most cases, the effects were statistically stronger for importers in emerging countries. Import demand for horticultural commodities in developed countries has been driven primarily by prices and the level of trade openness while income and diet considerations were more important in emerging countries. Furthermore, our results show that the determinants of import demand differed across the six models, and therefore, information can be lost when data for horticultural commodities are aggregated.Emerging markets, Horticultural commodities, Import demand, International trade, Agricultural and Food Policy, International Relations/Trade, Q17,

De l’alliance à la gouvernance : logiques d’action et logiques d’acteurs dans un centre financieraux entreprises Desjardins

Cet article rend compte d’une démarche originale pour analyser une stratégie d’alliance dans le secteur coopératif financier québécois (St-Pierre, 2003). On propose un cadre d’analyse inhabituel qui combine deux écoles de pensées traditionnellement opposées l’une à l’autre, soit l’approche des économies de la grandeur (Boltanski et Thévenot, 1991 ; Boltanski et Chiapello, 1999) qui met l’accent sur les « logiques d’action », la « coordination » et le « compromis », et l'analyse stratégique (Crozier et Friedberg, 1977 ; Francfort et a., 1995) qui utilise les concepts de « logiques d’acteurs », de « pouvoir » et d’« enjeux ». Comme nous le montre Amblard et al (1996), ces deux écoles sont éminemment compatibles. Toutefois, à notre connaissance, aucune étude n’a démontré empiriquement cette réconciliation. Le cas d’un centre financier aux entreprises Desjardins nous semble un excellent terrain de recherche puisque plusieurs tensions pèsent sur ce type d’organisation, ce qui nous permettra de mettre en lumière les différentes logiques d’action et logiques d’acteurs. Ce faisant, nous découvrirons de nouveaux modes de gouvernance en contexte coopératif. JulieCette recherche a été entreprise grâce, en partie, au soutien financier du Programme des chaires de recherche du Canada

Modèle québécois de développement et gouvernance : entre le partenariat et le néolibéralisme ?

Depuis les années 1960, on voit se déployer trois modèles de développement successifs au Québec : fordiste, partenarial et, tout récemment, néolibéral. Nous présentons d'abord les particularités québécoises de ces trois modèles et les modes de gouvernance qui y sont associé. Le fordisme y prend une coloration particulière puisque des compromis entre l'État, le patronat et les syndicats s'établissent pour favoriser la modernisation des entreprises et le développement régional. Les bases du partenariat s'élargissent ensuite, notamment sous la pression des mouvements sociaux. Aujourd'hui, le partenariat État-marché-société civile prend un nouveau sens, sous l'influence d'un gouvernement de tendance néo-libérale. Nous illustrons ensuite ces divers modèles par deux exemples, celui du développement économique communautaire (DEC) et celui du logement communautaire (coopératif et associatif). Ces deux secteurs ont ceci de particulier qu'ils articulent le développement économique au développement social. En ce sens, ils remettent en question le cloisonnement des politiques publiques. Ceci, en grande partie grâce au rôle joué par des groupes sociaux émanant de la société civile dans la construction du modèle partenarial. Celui-ci prend un dynamique ascendante (bottom-up), favorisant un nouvel arrangement entre l'État, le marché et la société civile. Cette articulation du développement économique et du développement social se recrée sur une base locale, à l'initiative des citoyens, souvent conjuguée à celle des administrations publiques. Les acquis de ce modèle sont aujourd'hui mis à risque par une conception étroite des dynamiques de développement, notamment la négation des effets d'externalités et de « spillover » de ces externalités sur la communauté dans son ensemble. Nous concluons sur les leçons à tirer de ces expériences

A renormalization fixed point for Lorenz maps

A Lorenz map is a Poincar\'e map for a three-dimensional Lorenz flow. We describe the theory of renormalization for Lorenz maps with a critical point and prove that a restriction of the renormalization operator acting on such maps has a hyperbolic fixed point. The proof is computer assisted and we include a detailed exposition on how to make rigorous estimates using a computer as well as the implementation of the estimates.Comment: 29 pages, 2 figure

Suppression of mitochondrial respiration through recruitment of p160 myb binding protein to PGC-1α : modulation by p38 MAPK

The transcriptional coactivator PPAR gamma coactivator 1 α (PGC-1α) is a key regulator of metabolic processes such as mitochondrial biogenesis and respiration in muscle and gluconeogenesis in liver. Reduced levels of PGC-1α in humans have been associated with type II diabetes. PGC-1α contains a negative regulatory domain that attenuates its transcriptional activity. This negative regulation is removed by phosphorylation of PGC-1α by p38 MAPK, an important kinase downstream of cytokine signaling in muscle and β-adrenergic signaling in brown fat. We describe here the identification of p160 myb binding protein (p160MBP) as a repressor of PGC-1α. The binding and repression of PGC-1α by p160MBP is disrupted by p38 MAPK phosphorylation of PGC-1α. Adenoviral expression of p160MBP in myoblasts strongly reduces PGC-1α's ability to stimulate mitochondrial respiration and the expression of the genes of the electron transport system. This repression does not require removal of PGC-1α from chromatin, suggesting that p160MBP is or recruits a direct transcriptional suppressor. Overall, these data indicate that p160MBP is a powerful negative regulator of PGC-1α function and provide a molecular mechanism for the activation of PGC-1α by p38 MAPK. The discovery of p160MBP as a PGC-1α regulator has important implications for the understanding of energy balance and diabetes

Collagen-mimetic peptide-modifiable hydrogels for articular cartilage regeneration

Regenerative medicine strategies for restoring articular cartilage face significant challenges to recreate the complex and dynamic biochemical and biomechanical functions of native tissues. As an approach to recapitulate the complexity of the extracellular matrix, collagen-mimetic proteins offer a modular template to incorporate bioactive and biodegradable moieties into a single construct. We modified a Streptococcal collagen-like 2 protein with hyaluronic acid (HA) or chondroitin sulfate (CS)-binding peptides and then cross-linked with a matrix metalloproteinase 7 (MMP7)-sensitive peptide to form biodegradable hydrogels. Human mesenchymal stem cells (hMSCs) encapsulated in these hydrogels exhibited improved viability and significantly enhanced chondrogenic differentiation compared to controls that were not functionalized with glycosaminoglycan-binding peptides. Hydrogels functionalized with CS-binding peptides also led to significantly higher MMP7 gene expression and activity while the HA-binding peptides significantly increased chondrogenic differentiation of the hMSCs. Our results highlight the potential of this novel biomaterial to modulate cell-mediated processes and create functional tissue engineered constructs for regenerative medicine applications

Import Demand for Horticultural Commodities in Developed and Emerging Countries

WP 2008-24 December 2008JEL Classification Codes: Q17International trade of horticultural commodities is increasingly important in many regions of the world, yet import patterns of key horticultural crops are understudied in the agricultural economics literature. Using data between 1991 and 2005, we estimate the drivers of per capita import demand for six of the most highly traded horticultural commodities. The own price elasticity estimates were negative in all import demand models and, in most cases, the effects were statistically stronger for importers in emerging countries. Import demand for horticultural commodities in developed countries has been driven primarily by prices and the level of trade openness while income and diet considerations were more important in emerging countries. Furthermore, our results show that the determinants of import demand differed across the six models, and therefore, information can be lost when data for horticultural commodities are aggregated