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Search Results: 1 - 10 of 138840 matches for " Roxane K. Boonstra "
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Fast Growth May Impair Regeneration Capacity in the Branching Coral Acropora muricata
Vianney Denis, Mireille M. M. Guillaume, Madeleine Goutx, Stéphane de Palmas, Julien Debreuil, Andrew C. Baker, Roxane K. Boonstra, J. Henrich Bruggemann
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072618
Abstract: Regeneration of artificially induced lesions was monitored in nubbins of the branching coral Acropora muricata at two reef-flat sites representing contrasting environments at Réunion Island (21°07′S, 55°32′E). Growth of these injured nubbins was examined in parallel, and compared to controls. Biochemical compositions of the holobiont and the zooxanthellae density were determined at the onset of the experiment, and the photosynthetic efficiency (Fv/Fm) of zooxanthellae was monitored during the experiment. Acropora muricata rapidly regenerated small lesions, but regeneration rates significantly differed between sites. At the sheltered site characterized by high temperatures, temperature variations, and irradiance levels, regeneration took 192 days on average. At the exposed site, characterized by steadier temperatures and lower irradiation, nubbins demonstrated fast lesion repair (81 days), slower growth, lower zooxanthellae density, chlorophyll a concentration and lipid content than at the former site. A trade-off between growth and regeneration rates was evident here. High growth rates seem to impair regeneration capacity. We show that environmental conditions conducive to high zooxanthellae densities in corals are related to fast skeletal growth but also to reduced lesion regeneration rates. We hypothesize that a lowered regenerative capacity may be related to limited availability of energetic and cellular resources, consequences of coral holobionts operating at high levels of photosynthesis and associated growth.
Duality and asymptotic geometries
H. J. Boonstra,B. Peeters,K. Skenderis
Physics , 1997, DOI: 10.1016/S0370-2693(97)01008-3
Abstract: We consider a series of duality transformations that leads to a constant shift in the harmonic functions appearing in the description of a configuration of branes. This way, for several intersections of branes, we can relate the original brane configuration which is asymptotically flat to a geometry of the type $adS_k \xx E^l \xx S^m$. The implications of our results for supersymmetry enhancement, M(atrix) theory at finite N, and for supergravity theories in diverse dimensions are discussed.
The domain-wall/QFT correspondence
H. J. Boonstra,K. Skenderis,P. K. Townsend
Physics , 1998, DOI: 10.1088/1126-6708/1999/01/003
Abstract: We extend the correspondence between adS-supergravities and superconformal field theories on the adS boundary to a correspondence between gauged supergravities (typically with non-compact gauge groups) and quantum field theories on domain walls.
Aorto-ventricular tunnel
Roxane McKay
Orphanet Journal of Rare Diseases , 2007, DOI: 10.1186/1750-1172-2-41
Abstract: In their original description of aorto – left ventricular tunnel, Edwards and Burchell [1] considered the malformation a "separation between the aorta and the heart", or type of aneurysm which "lay against the outflow tract of the right ventricle and origin of the pulmonary trunk". The term "aortico-left ventricular tunnel" was used subsequent to Levy's publication in 1963 [2], and "aorto-left ventricular tunnel" was introduced about ten years later by Ross and colleagues [3]. Recognizing that the tunnel may extend to either the left or the right ventricular cavity, the more general designation "aorto-ventricular tunnels" has recently been applied to this group of malformations [4]. The defect is not a component of any described genetic syndrome, although cystic medial degeneration has been observed in an ascending aortic aneurysm resected fifteen years after tunnel repair [5].An aorto-ventricular tunnel is an extracardiac channel which connects the ascending aorta above the sinutubular junction to the cavity of the left or right ventricle. Among 130 cases reported in the literature, more than 90% communicated with the left ventricle (Figure 1). It differs from a ruptured sinus of Valsalva aneurysm (sinus of Valsalva fistula) in having its vascular orifice in the tubular aorta, rather than a sinus of the aortic valve, and in passing outside the heart into the tissue plane between the muscular subpulmonary infundibulum and the aortic valvar sinuses. The aortic opening of most tunnels lies above the right coronary sinus of Valsalva. In these cases, the tunnel virtually always communicates with the left ventricle in the fibrous triangle beneath the left – right coronary commissure, or the right ventricle immediately above or below the subpulmonary infundibulum. In aorto-left ventricular tunnel, the right coronary aortic leaflet is thus unsupported for a variable portion of its hinge-point and may appear to arise from a bar of fibrous tissue spanning the aortic root [5]
O letramento escolar e os textos da divulga??o científica - a apropria??o dos gêneros de discurso na escola
Rojo, Roxane;
Linguagem em (Dis)curso , 2008, DOI: 10.1590/S1518-76322008000300009
Abstract: in this paper we define school literacy based on the approach of multiple and situated literacies (multiliteracies) and, from a bakhtinian perspective, we briefly describe some pop science genres (dictionary/encyclopedia entries, papers, reportages) that are frequently taught. viewing the process of genre appropriation as an important aspect of school literacy practices and processes, in the second part of the paper we analyze how the process appropriation of pop science genres occurs in classrooms, examining expositions (seminars) of secondary school students (7th and 8th grades). the results show that pop science texts, although very frequent in school textbooks and discursive practices, are not effectively approached and their appropriation by the students occurs by language immersion, which raises difficulties specifically related to specialized languages.
O letramento escolar e os textos da divulga o científica – a apropria o dos gêneros de discurso na escola
Roxane Rojo
Linguagem em (Dis)curso , 2008,
Abstract: Neste ensaio, define-se letramento escolar na perspectiva dos letramentos múltiplos e situados e, a partir de uma discuss o sobre os textos da divulga o científica, caracterizam-se brevemente, na perspectiva bakhtiniana, alguns dos gêneros discursivos da divulga o científica didatizados na escola (verbetes, artigos, reportagens). Entendendo o processo de apropria o de gêneros discursivos como um aspecto importante das práticas e dos processos de letramento escolar, o ensaio, em sua segunda parte, traz uma análise de como este processo de apropria o dos gêneros da divulga o científica se dá nas salas de aula, a partir de seminários realizados por alunos do Ensino Fundamental II (EFII). Os resultados indicam que, embora muito presentes nos livros e práticas discursivas escolares, os textos da divulga o científica n o s o efetivamente abordados no ensino, e sua apropria o se faz por imers o, colocando especialmente problemas em rela o às linguagens especializadas.
Simone Mazauric, Fontenelle et l'invention de l'histoire des sciences à l'aube des Lumières
Roxane Argyropoulos
Historical Review , 2009,
Abstract: No abstract
Les "Lettere ateniesi" de Markos Réniéris. Une herméneutique des ruines
Roxane Argyropoulos
Historical Review , 2010,
Abstract: No abstract
Conceptualising intangible heritage in the Tropenmuseum, Amsterdam: the Layla and Majnun story as a case study
Sadiah Boonstra
International Journal of Intangible Heritage , 2009,
Abstract: The Tropenmuseum in Amsterdam, in the Netherlands, was founded as a colonial museum in the 19th century in which experts (‘outsiders’) presented their view of other cultures. In the 20th century the Netherlands became a multicultural society. As a result, the museum had to redefine its function in society. In an attempt to rethink therelation between the content of its exhibitions and its audience, the Tropenmuseum refurbished all the museum galleries between 1990 and 2008. During the refurbishment the museum started to experiment with intangible heritage for which the story of Layla and Majnun was chosen as a case study. The museum collected four separate contemporary cultural expressions of the story, accompanied by audiovisual recordings of performances.The experiment was so successful that it functioned as a catalyst for the final refurbished gallery, entitled Travelling Tales, which is entirely devoted to intangible heritage.Based on research into the Layla and Majnun collection, I argue that the voices and views of the artists mirror the manifold perspectives that people have to various forms of intangible and tangible culture. The presentation of this multitude of views in the exhibition reflects the complexity of identification processes and therefore goes beyond notions of ‘self’ and ‘other’. In this respect, the Tropenmuseum functions as a forum where variousopinions meet and as a space for intercultural encounters.
National savings and the international investment position: what does the current account tell us?
Wim Boonstra
Zbornik Radova Ekonomskog Fakulteta u Rijeci : ?asopis za Ekonomsku Teoriju i Praksu , 2008,
Abstract: This article discusses the relation between the balance of payments and the international investment position of countries. It starts with the observation that the net international investment position of many countries is developing independently from their current account balances. This phenomenon can be explained by valuechanges of cross border assets and liabilities that are not registered on the balance of payments. These value changes have impact on the net external investment position of a country as soon as the returns on its external assets and liabilities start to diverge. Such divergent developments can be attributed to currency developments,differences of composition of external assets and liabilities and performance effects. These mechanisms are discussed, followed by two case studies, viz. the case of the ‘black hole’ (the Netherlands) and the case of ‘dark matter’(the US). Understanding the relation between the international investment position of a country and its balance of payments becomes more and more relevant as countries prepare for ageing of the population. Some countries explicitly aim at the creation of a national savings surplus in order to create a net international asset position. The consequences of the failure of such a policy are discussed in a concluding paragraph.
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