3,947 research outputs found
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 lâalliance Ă la gouvernance : logiques dâaction et logiques dâacteurs dans un centre financieraux entreprises Desjardins
Cet article rend compte dâune dĂ©marche originale pour analyser une stratĂ©gie dâalliance dans le secteur coopĂ©ratif financier quĂ©bĂ©cois (St-Pierre, 2003). On propose un cadre dâanalyse inhabituel qui combine deux Ă©coles de pensĂ©es traditionnellement opposĂ©es lâune Ă lâautre, soit lâapproche des Ă©conomies de la grandeur (Boltanski et ThĂ©venot, 1991 ; Boltanski et Chiapello, 1999) qui met lâaccent sur les « logiques dâaction », la « coordination » et le « compromis », et l'analyse stratĂ©gique (Crozier et Friedberg, 1977 ; Francfort et a., 1995) qui utilise les concepts de « logiques dâacteurs », de « pouvoir » et dâ« enjeux ». Comme nous le montre Amblard et al (1996), ces deux Ă©coles sont Ă©minemment compatibles. Toutefois, Ă notre connaissance, aucune Ă©tude nâa dĂ©montrĂ© empiriquement cette rĂ©conciliation. Le cas dâun centre financier aux entreprises Desjardins nous semble un excellent terrain de recherche puisque plusieurs tensions pĂšsent sur ce type dâorganisation, ce qui nous permettra de mettre en lumiĂšre les diffĂ©rentes logiques dâaction et logiques dâacteurs. Ce faisant, nous dĂ©couvrirons de nouveaux modes de gouvernance en contexte coopĂ©ratif.
JulieCette recherche a été entreprise grùce, en partie, au soutien financier du Programme des chaires de recherche du Canada
ModÚle québécois de développement et gouvernance : entre le partenariat et le néolibéralisme ?
Depuis les annĂ©es 1960, on voit se dĂ©ployer trois modĂšles de dĂ©veloppement successifs au QuĂ©bec : fordiste, partenarial et, tout rĂ©cemment, nĂ©olibĂ©ral. Nous prĂ©sentons d'abord les particularitĂ©s quĂ©bĂ©coises de ces trois modĂšles et les modes de gouvernance qui y sont associĂ©. Le fordisme y prend une coloration particuliĂšre puisque des compromis entre l'Ătat, le patronat et les syndicats s'Ă©tablissent pour favoriser la modernisation des entreprises et le dĂ©veloppement rĂ©gional. Les bases du partenariat s'Ă©largissent ensuite, notamment sous la pression des mouvements sociaux. Aujourd'hui, le partenariat Ătat-marchĂ©-sociĂ©tĂ© civile prend un nouveau sens, sous l'influence d'un gouvernement de tendance nĂ©o-libĂ©rale. Nous illustrons ensuite ces divers modĂšles par deux exemples, celui du dĂ©veloppement Ă©conomique communautaire (DEC) et celui du logement communautaire (coopĂ©ratif et associatif). Ces deux secteurs ont ceci de particulier qu'ils articulent le dĂ©veloppement Ă©conomique au dĂ©veloppement social. En ce sens, ils remettent en question le cloisonnement des politiques publiques. Ceci, en grande partie grĂące au rĂŽle jouĂ© par des groupes sociaux Ă©manant de la sociĂ©tĂ© civile dans la construction du modĂšle partenarial. Celui-ci prend un dynamique ascendante (bottom-up), favorisant un nouvel arrangement entre l'Ătat, le marchĂ© et la sociĂ©tĂ© civile. Cette articulation du dĂ©veloppement Ă©conomique et du dĂ©veloppement social se recrĂ©e sur une base locale, Ă l'initiative des citoyens, souvent conjuguĂ©e Ă celle des administrations publiques. Les acquis de ce modĂšle sont aujourd'hui mis Ă risque par une conception Ă©troite des dynamiques de dĂ©veloppement, notamment la nĂ©gation des effets d'externalitĂ©s et de « spillover » de ces externalitĂ©s sur la communautĂ© dans son ensemble. Nous concluons sur les leçons Ă tirer de ces expĂ©riences
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 ÎČ-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
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