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Different Histories (different + history)
Selected AbstractsViscous behaviour of dry sandINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2007D. Pham Van Bang Abstract Tests on air-dried Hostun sand were performed on a newly developed triaxial apparatus, which allows static and dynamic measurements at ,Département Génie Civil et Bâtiment' (DGCB) of ENTPE. The prototype was designed to perform tests in order to investigate the viscous effects of sand from small strain (some 10,5m/m) up to intermediate strain (some 10,3m/m). The accuracy of the measuring system is ensured by the use of local non-contact displacements transducers and by the use of an internal load cell. The viscous behaviour of sand is experimentally studied for loose and dense specimens for confining pressure values from 80 up to 400 kPa and considering different histories of loading. Three types of viscous loading: creep periods; stress relaxation periods; and paths with stepwise changes in the strain rate are specifically analysed. The proposed viscous modelling is issued from a three-component general framework and is able to reproduce the experimental observations. More specifically, the peculiar behaviour of sand observed during a stepwise increase or decrease in the strain rate is detailed and modelled by the viscous evanescent (VE) model, developed at DGCB/ENTPE. Based on the three types of viscous tests, a simple relation is finally proposed for the viscous parameters of the VE model. Comparisons between data and simulations validate the approach. Copyright © 2007 John Wiley & Sons, Ltd. [source] Contrasting phylogeographies inferred for the two alpine sister species Cardamine resedifolia and C. alpina (Brassicaceae)JOURNAL OF BIOGEOGRAPHY, Issue 1 2009Judita Lihová Abstract Aim, We use Cardamine alpina and C. resedifolia as models to address the detailed history of disjunctions in the European alpine system. These species grow on siliceous bedrock: C. alpina in the Alps and Pyrenees, and C. resedifolia in several mountain ranges from the Sierra Nevada to the Balkans. We explore differentiation among their disjunct populations as well as within the contiguous Alpine and Pyrenean ranges, and compare the phylogeographical histories of these diploid sister species. We also include samples of the closely related, arctic diploid C. bellidifolia in order to explore its origin and post-glacial establishment. Location, European alpine system, Norway and Iceland. Methods, We employed amplified fragment length polymorphisms (AFLPs). AFLP data were analysed using principal coordinates analysis, neighbour joining and Bayesian clustering, and measures of diversity and differentiation were computed. Results, For the snow-bed species C. alpina (27 populations, 203 plants) we resolved two strongly divergent lineages, corresponding to the Alps and the Pyrenees. Although multiple glacial refugia were invoked in the Pyrenees, we inferred only a single one in the Maritime Alps , from which rapid post-glacial colonization of the entire Alps occurred, accompanied by a strong founder effect. For C. resedifolia (33 populations, 247 plants), which has a broader ecological amplitude and a wider distribution, the genetic structuring was rather weak and did not correspond to the main geographical disjunctions. This species consists of two widespread and largely sympatric main genetic groups (one of them subdivided into four geographically more restricted groups), and frequent secondary contacts exist between them. Main conclusions, The conspicuously different histories of these two sister species are likely to be associated with their different ecologies. The more abundant habitats available for C. resedifolia may have increased the probability of its gradual migration during colder periods and also of successful establishment after long-distance dispersal, whereas C. alpina has been restricted by its dependence on snow-beds. Surprisingly, the arctic C. bellidifolia formed a very divergent lineage with little variation, contradicting a scenario of recent, post-glacial migration from the Alps or Pyrenees. [source] Historic and contemporary levels of genetic variation in two New Zealand passerines with different histories of declineJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2007S. S. TAYLOR Abstract We compared historic and contemporary genetic variation in two threatened New Zealand birds (saddlebacks and robins) with disparate bottleneck histories. Saddlebacks showed massive loss of genetic variation when extirpated from the mainland, but no significant loss of variation following a severe bottleneck in the 1960s when the last population was reduced from ,1000 to 36 birds. Low genetic variation was probably characteristic of this isolated island population: considerably more genetic variation would exist in saddlebacks today if a mainland population had survived. In contrast to saddlebacks, contemporary robin populations showed only a small decrease in genetic variation compared with historical populations. Genetic variation in robins was probably maintained because of their superior ability to disperse and coexist with introduced predators. These results demonstrate that contemporary genetic variation may depend more greatly on the nature of the source population and its genetic past than it does on recent bottlenecks. [source] Subjective realities: Perceptions of identity and conflict in Ghana and NigeriaJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 4 2009Arnim Langer Abstract Drawing on perceptions survey research conducted in Ghana and Nigeria, this article explores whether differences in the salience of ethnic and religious identities and interethnic and religious attitudes and interaction, might contribute to explaining the different histories of violence and conflict in these two countries. Based on the finding that ethnic identities are more salient in the Nigerian sampled communities than in the Ghanaian ones, whereas national and occupational identities are more salient in Ghana than in Nigeria, the authors suggest that ethnic mobilisation is more likely to be successful in Nigeria than in Ghana. The authors argue that this finding could possibly explain why Nigeria has experienced more incidents of violent conflicts along ethnic lines than Ghana; although the causality is likely to go both ways. Copyright © 2009 John Wiley & Sons, Ltd. [source] The creation of coevalness and the danger of homochronismTHE JOURNAL OF THE ROYAL ANTHROPOLOGICAL INSTITUTE, Issue 1 2008Kevin Birth Johannes Fabian's Time and the Other criticized anthropology for creating representations that placed the Other outside the flow of time. Fabian offered the ethnographic portrayal of coevalness as a solution to this problem. This article explores four challenges to the representation of coevalness: the split temporalities of the ethnographer; the multiple temporalities of different histories; the culturally influenced phenomenological present; and the complicated relationship between culturally variable concepts of being and becoming and cultural concepts of time. Based on these challenges, this article argues that some attempts at ethnographic coevalness have fostered a temporal framework of homochronism which subsumes the Other into academic discourses of history. To achieve coevalness and to avoid homochronism and allochronism, it is necessary to represent the temporal frameworks that research subjects use to forge coevalness with ethnographers, and to place these frameworks in relationship to commonly used academic representations of time and history. Résumé Dans son livre Le Temps et les Autres, Johannes Fabian critiquait la création par l'anthropologie de représentations plaçant l'Autre en dehors du flux du temps. Selon lui, la description ethnographique de la contemporanéité pourrait être la solution à ce problème. Le présent article explore les quatre difficultés que pose la représentation de la contemporanéité : temporalités dissociées de l'ethnographe, temporalités multiples des différentes histoires, présent phénoménologique culturellement informé, relation complexe entre les concepts culturellement variables de l'être et du devenir et les concepts culturel du temps. Sur la base de ces difficultés, l'auteur avance que certaines tentatives de contemporanéité ethnographique ont suscité un cadre temporel d'homochronie qui subsume l'Autre dans les discours académiques sur l'histoire. Pour parvenir à la contemporanéité et éviter homochronie et allochronie, il est nécessaire de représenter les cadres temporels utilisés par les enquêtés pour forger la contemporanéité avec les ethnographes et de resituer ces cadres en relation avec les représentations académiques du temps et de l'histoire qui prévalent habituellement. [source] Consistent geographic structure among multiple nuclear sequences and cpDNA polymorphisms of Cardamine nipponica Franch. et Savat. (Brassicaceae)MOLECULAR ECOLOGY, Issue 13 2008HAJIME IKEDA Abstract Molecular phylogeography has inferred the history of differentiation between regions and/or among populations following the Pleistocene climatic oscillations, mostly based on the genetic structure of organelle DNA. However, such genetic structure only reflects the history of a single gene, and studies based on single-copy genes of nuclear DNA (nDNA) are required for phylogeography, although their efficiency remains unclear. To examine the utility of nDNA loci, the genetic structures of three genes from Cardamine nipponica, which is closely related to the model species Arabidopsis thaliana, were elucidated: the nDNA genes DET1, PHYA, PHYE, as well as chloroplast DNA (cpDNA). In 279 individuals collected from throughout the range of the species, strong genetic differentiation between northern and central Japan was found for all loci. This result suggested that populations in central Japan experienced a different history from those in northern Japan during the Pleistocene climatic oscillations. In addition, the evidence of refugia at the edges of the distribution, where the genetic structure was less influenced by colonization following range expansion, was shown for several loci. The specific genetic structure within the southernmost populations of northern Japan suggested that this region was also isolated during range expansion. Hence, the consistent history among loci and a more detailed history from several loci indicated that cpDNA can represent the history of vicariance and demonstrated the efficiency of single-copy nuclear genes in phylogeography. [source] Complete nucleotide sequence of mitochondrial DNA in White Leghorn and White Plymouth Rock chickensANIMAL SCIENCE JOURNAL, Issue 5 2003Masahide NISHIBORI ABSTRACT Among the chicken breeds, White Leghorn (WL) and White Plymouth Rock (WR) are major breeds and have different history in their establishments. Whole mitochondrial DNA of the breeds were sequenced in order to elucidate the genetic relationship between the breeds. The lengths of the two WL and two WR mitochondrial DNA were found to be 16 788 and 16 785 base pairs, respectively. When the DNA sequences were compared, the similarity was found to be 99.96% (six nucleotide differences). In addition, the present study conformed the existence of an extra nucleotide ,C' in NADH dehydrogenase subunit 3 (ND3) of the chicken mitochondrial DNA, which has been consistently observed in Galliformes. [source] Mangrove Distribution during the Holocene in Tribugí Gulf, Colombia,BIOTROPICA, Issue 1 2000Carlos Jaramillo ABSTRACT Neotropical mangrove ecosystems have undergone drastic changes in terms of extension and floristic composition during Plio,Pleistocene times. It is unclear if the northern Pacific coast of Colombia has been occupied continuously by mangroves during the last 5000 years, or if their presence is a recent phenomenon. Two basic questions were asked: (1) is the establishment of mangroves recent?; and (2) what were the dominant floral taxa during the late Holocene? In the Gulf of Tribugí, northern Colombian Pacific, 22 sediment cores were drilled to a maximum depth of 2 m in a diverse suite of mangrove substrates and positions relative to the shoreline. Data were gathered from sedimentological descriptions, palynological analyses, and radiocarbon dating of these cores. During the last 4500 years, mangroves in the southern area of the Tribugí Gulf have remained floristically stable and dominated by Rhizophora. The abundant presence of Acrostichum aureum is recent, probably related to human activities. In contrast, two areas in the northern part of the Gulf show a different history. In the first area, the establishment of mangrove has been relatively recent (ca 2600 yr), probably a result of local subsidence due to tectonic faulting; this mangrove forest was and is dominated by Pelliciem rhizophorae. In the second area, mangrove pollen was not found in sediments younger than 2500 years, suggesting that the scarce presence of mangrove in the area is a result of recent colonization, and not due to logging as previously thought. RESUMEN Ecosistemas Neotropicales de manglar han sufrido cambios dramáticos tanto en su extensión como en su composición florística asociados con cambios climáticos y variaciories del nivel del mar durante el Plio-Pleistoceno. No es claro si la costa norte del Pacífico Colombiano ha sido ocupada por manglares durante los últimos 5000 años. Quisimos responder dos preguncas básicas: Es el establecimiento del manglar un fenómeno reciente? y Cuales fueron las especies que dominaron el mangle durante el Holoceno? Para responder estas preguntas extrajimos 22 corazones de sedimento cn el Golfo de Tribugá, costa norte del Pacífico Colombiano. Los corazones, de máximo dos metros de profundidad, fueron analizados con méttodos palinológicos, sedimentológicos y dataciones radiométricas. El tipo de sedimento más común fué lodo arenoso verde altamente bioperturbado por actividad infaunal. Los manglares mostraron ser muy estables y doniinados por Rhizophora en la mayoría de los sitios estudiados, con excepción de los manglares en la Chunga (Utría) y El Valle. Allí 10s manglares se establecieron recientemente. En la Chunga, un ascenso relativo del nivel del mar hace aproximadamente 2600 años a.p., probablemente local y asociado con la falla de Utría, posibilitó la colonización del sustrato por Pelliciera rhizophorae; es incierto determinar si este ascenso aún se esta produciendo. En el Valle, el escaso establecimiento del manglar es un proceso reciente de colonización y no una reducción en la cobertura del manglar producto de actividades humanas como previamente se asumía. [source] | |||||||||||||