2,703 research outputs found

    Archaeological Investigations between Cayenne Island and the Maroni River

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    Stratigraphic archaeological research in French Guiana is barely 50 years old and has been conducted primarily in the coastal zone, stretching approximately between 5 and 50 kilometres from the Atlantic coast to the Precambrian Shield. This bias, mainly caused by means of modern infrastructure, has sketched an archaeological record concerning pre-Columbian French Guiana focussing on the Late Ceramic Age (AD 900-1500) of Cayenne Island as well as the western Holocene coastal plains. The present study contains the results of six archaeological investigations, conducted from a compliance archaeological perspective, in order to enhance our knowledge of the afore-mentioned coastal area. It not only presents us with fresh archaeological data on the (Late) Archaic and Early Ceramic Age, a hiatus that is now partially filled up, but also sheds new light on the Late Ceramic Age of this specific region concerning funerary rites, ceramic series and subsistence economy. Martijn van den Bel studied History and Archaeology of Indigenous America at Leiden University and graduated in 1995 with an ethnoarchaeological study on the Palikur potters of French Guiana. Currently he works as a project leader for Inrap in French Guiana. He carries out compliance archaeological research in the French Guiana and the French Lesser Antilles. Next to archaeology, Martijn is interested in the early history of the Guianas and the Lesser Antilles, notably the encounter between Amerindians and Europeans during the 16th and 17th century, resulting in various publications

    The Tapuia of Northeastern Brazil in Dutch sources (1628–1648)

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    This book presents the transcriptions and annotated translations of fifteen key historical documents concerning the Tapuia indigenous people written just before and during the Dutch occupation of northeastern Brazil. The selected documents vary widely in type, including letters, descriptions, reports, first-person declarations, diaries, and transcripts of interrogations, thereby showcasing different perspectives and audiences. Some of the documents were authored by European writers, while others register indigenous voices somewhat more directly in the form of interviews or declarations.These texts provide important first-hand information about the Tapuia and other indigenous peoples during the Dutch conquest, revealing their cultural practices and knowledge while also detailing their strategic engagements with each other and with different European colonizers.Horizon 2020(H2020)ERC Agreement No. 715423Heritage of Indigenous People

    Nouveaux apports sur l’archéologie du littoral de Guyane : de la préhistoire à la conquête

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    En Guyane française, les recherches archéologiques structurées ne datent que du début des années 1970. Elles furent synthétisées par Stéphen Rostain au début des années 1990. Le cadre chrono-culturel établi alors se concentrait surtout sur la bande littorale entre les rivières de Kourou et de l’Oyapock et sur la période entre 900 et 1700 de notre ère. Cette étude résume les résultats de six fouilles archéologiques préventives plus récentes. Celles-ci permettent d’abord d’étoffer le cadre chrono-culturel de la préhistoire de ce département français. En effet des données nouvelles élargissent substantiellement ce cadre sur l’Âge archaïque et sur la période céramique ancienne, deux époques inconnues jusque-là. De nouveaux éléments renouvellent aussi certaines perspectives de la période céramique récente, en particulier sur les pratiques funéraires, les complexes céramiques et l’alimentation des Amérindiens.In French Guiana, structured archaeological research only started in the early 1970s. Its results have been synthesized by Stéphen Rostain twenty year later. The proposed chronocultural framework focused mainly on the coastal plains situated between the Oyapock and Kourou Rivers for the Late Ceramic Age, between AD 900 and 1700. This study presents the condensed results of six recent compliance archaeological excavations. They permit us firstly to enrich the existing framework of this overseas French department by presenting new data concerning the Archaic and Early Ceramic Ages, hitherto undiscovered episodes, substantially enlarging this framework. Furthermore, new elements concerning the Late Ceramic Age renew certain aspects, notably concerning funerary practices, ceramic complexes and food consumption of the prehistoric Amerindians.Na Guiana Francesa, pesquisas arqueológicas estruturadas só começaram no início da década de 1970 e seus resultados foram sintetizados por Stéphen Rostain no início dos anos 1990. O quadro cronocultural proposto focava principalmente nas planícies costeiras situadas entre os rios Oiapoque e Kourou para o Período Cerâmico tardio, entre 900 e 1700 AD. Este estudo apresenta os resultados condensados de seis escavações de arqueologia preventiva. Eles nos permitem, primeiramente, enriquecer o quadro existente deste departamento ultramarino francês; além disso, são apresentados aqui novos dados sobre os Períodos Cerâmicos arcaico e inicial, episódios até então não descobertos, ampliando substancialmente esse panorama. Finalmente, novos elementos relativos ao Período Cerâmico tardio renovam certos aspectos, notadamente, sobre práticas funerárias, complexos cerâmicos e consumo de alimentos das populações ameríndias pré-históricas

    Archaeological investigations between Cayenne Island and the Maroni river : a cultural sequence of western coastal Franche Guiana from 5000 BP to present

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    2 septembre 2015 Université de Leyde  Membres du Jury Directeurs de thèseCorinne L. Hofman, Professeure, université de LeydeArie Boomert, Chercheur, université de LeydeRapporteurs Maarten E.R.G.N. Jansenn, Professeur, université de LeydeEduardo Góes Neves, Professeur, Musée d’archéologie et d’ethnologie de l’université de São PauloEithne B. Carlin, Chercheuse, université de LeydeExaminateurs Humphrey H. H. Kanhai, Professeur, université de LeydeDavid R. Fontijn, Professeur, université de Leyd..

    On the classification of type D spacetimes

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    We give a classification of the type D spacetimes based on the invariant differential properties of the Weyl principal structure. Our classification is established using tensorial invariants of the Weyl tensor and, consequently, besides its intrinsic nature, it is valid for the whole set of the type D metrics and it applies on both, vacuum and non-vacuum solutions. We consider the Cotton-zero type D metrics and we study the classes that are compatible with this condition. The subfamily of spacetimes with constant argument of the Weyl eigenvalue is analyzed in more detail by offering a canonical expression for the metric tensor and by giving a generalization of some results about the non-existence of purely magnetic solutions. The usefulness of these results is illustrated in characterizing and classifying a family of Einstein-Maxwell solutions. Our approach permits us to give intrinsic and explicit conditions that label every metric, obtaining in this way an operational algorithm to detect them. In particular a characterization of the Reissner-Nordstr\"{o}m metric is accomplished.Comment: 29 pages, 0 figure

    Bioinformatics-based assessment of the relevance of candidate genes for mutation discovery

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    The bioinformatics resources provide a wide range of tools that can be applied in different areas of mutation screening. The enormous and constantly increasing amount of genomic data obtained in plant-oriented molecular studies requires the development of efficient techniques for its processing. There is a wide range of bioinformatics tools which can aid in the course of mutation discovery. The following chapter focuses mainly on the application of different tools and resources to facilitate a Targeting-Induced Local Lesions in Genomes (TILLING) analysis. TILLING is a technique of reverse genetics that applies a traditional mutagenesis to create DNA libraries of mutagenised individuals that are then subjected to high-throughput screening for the identification of mutations. The bioinformatics tools have shown to be useful in supporting the process of candidate gene selection for mutation screening. The availability of bioinformatics software and experimental data repositories provides a powerful tool which enables a process of multi-database mining. The existing raw experimental data (genomics-related information, expression data, annotated ontologies) can be interpreted in terms of a new biological context. This may help in selecting the proper candidate gene for mutation discovery that is controlling the target phenotype. The mutation screening using a TILLING strategy requires a former knowledge of the full genomic sequence of the gene which is of interest. Depending on whether a fully sequenced genome of a particular species is available, different bioinformatics tools can facilitate this process. Specific tools can be also useful for the identification of possible gene paralogs which may mask the effect of mutated gene. Bioinformatics resources can also support the selection of gene fragments most prone to acquire a deleterious nucleotide change. Finally, there are available tools enabling a proper design of oligonucleotide primers for the amplification of a gene fragment for the purpose of mutation screening

    Detailed Radio to Soft Gamma-ray Studies of the 2005 Outburst of the New X-ray Transient XTE J1818-245

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    XTE J1818-245 is an X-ray nova that experienced an outburst in 2005, first seen by the RXTE satellite. The source was observed simultaneously at various wavelengths up to soft gamma-rays with the INTEGRAL satellite, from 2005 February to September. X-ray novae are extreme systems that often harbor a black hole, and are known to emit throughout the electromagnetic spectrum when in outburst. We analyzed radio, (N)IR, optical, X-ray and soft gamma-ray observations and constructed simultaneous broad-band X-ray spectra. Analyzing both the light curves in various energy ranges and the hardness-intensity diagram enabled us to study the long-term behavior of the source. Spectral parameters were typical of the Soft Intermediate States and the High Soft States of a black hole candidate. The source showed relatively small spectral variations in X-rays with considerable flux variation in radio. Spectral studies showed that the accretion disc cooled down from 0.64 to 0.27 keV in 100 days and that the total flux decreased while the relative flux of the hot medium increased. Radio emission was detected several times, and, interestingly, five days after entering the HSS. Modeling the spectral energy distribution from the radio to the soft gamma-rays reveals that the radio flares arise from several ejection events. XTE J1818-245 is likely a black hole candidate transient source that might be closer than the Galactic Bulge. The results from the data analysis trace the physical changes that took place in the system at a maximum bolometric luminosity of (0.4-0.9)e38 erg/s (assuming a distance between 2.8-4.3 kpc) and they are discussed within the context of disc and jet models.Comment: Accepted for publication in Astronomy and Astrophysics. 11 Figures, 3 Table

    Complete classification of purely magnetic, non-rotating and non-accelerating perfect fluids

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    Recently the class of purely magnetic non-rotating dust spacetimes has been shown to be empty (Wylleman, Class. Quant. Grav. 23, 2727). It turns out that purely magnetic rotating dust models are subject to severe integrability conditions as well. One of the consequences of the present paper is that also rotating dust cannot be purely magnetic when it is of Petrov type D or when it has a vanishing spatial gradient of the energy density. For purely magnetic and non-rotating perfect fluids on the other hand, which have been fully classified earlier for Petrov type D (Lozanovski, Class. Quant. Grav. 19, 6377), the fluid is shown to be non-accelerating if and only if the spatial density gradient vanishes. Under these conditions, a new and algebraically general solution is found, which is unique up to a constant rescaling, which is spatially homogeneous of Bianchi type VI0VI_0, has degenerate shear and is of Petrov type I(M∞)M^\infty) in the extended Arianrhod-McIntosh classification. The metric and the equation of state are explicitly constructed and properties of the model are briefly discussed. We finally situate it within the class of normal geodesic flows with degenerate shear tensor.Comment: 12 pages; introduction partly rewritten, notation made more clear, table of results adde

    Phloem loading in the sucrose-export-defective (SXD-1) mutant maize is limited by callose deposition at plasmodesmata in bundle sheath-vascular parenchyma interface

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    Using Lucifer Yellow we have demonstrated that the phloem-loading pathway from the mesophyll to the bundle sheath-vascular parenchyma interface in Zea mays source leaves follows a symplasmic route in small and intermediate vascular bundles in control as well as in the green sections of mutant sucrose-export-defective (SXD-1) plants. In the anthocyanin-rich mutant leaf sections, Lucifer Yellow transport was prohibited along the same path, at the bundle sheath-vascular parenchyma interface in particular. Plasmodesmata at the latter interface in SXD-1 anthocyanin-rich leaf sections appear to be structurally altered through callose deposition at the plasmodesmal orifices. We suggest that a transport bottleneck at the bundle sheath-vascular parenchyma interface is thus orchestrated and regulated through callose formation, preventing symplasmic transport across this important loading interface
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