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The Galois closure of the Garcia-Stichtenoth tower  [PDF]
Alexey Zaytsev
Mathematics , 2005,
Abstract: We describe the Galois closure of the Garcia-Stichtenoth tower and prove that it is optimal.
Diversity and Distribution of Symbiodinium Associated with Seven Common Coral Species in the Chagos Archipelago, Central Indian Ocean  [PDF]
Sung-Yin Yang, Shashank Keshavmurthy, David Obura, Charles R. C. Sheppard, Shakil Visram, Chaolun Allen Chen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035836
Abstract: The Chagos Archipelago designated as a no-take marine protected area in 2010, lying about 500 km south of the Maldives in the Indian Ocean, has a high conservation priority, particularly because of its fast recovery from the ocean-wide massive coral mortality following the 1998 coral bleaching event. The aims of this study were to examine Symbiodinium diversity and distribution associated with scleractinian corals in five atolls of the Chagos Archipelago, spread over 10,000 km 2. Symbiodinium clade diversity in 262 samples of seven common coral species, Acropora muricata, Isopora palifera, Pocillopora damicornis, P. verrucosa, P. eydouxi, Seriatopora hystrix, and Stylophora pistillata were determined using PCR-SSCP of the ribosomal internal transcribed spacer 1 (ITS1), PCR-DDGE of ITS2, and phylogenetic analyses. The results indicated that Symbiodinium in clade C were the dominant symbiont group in the seven coral species. Our analysis revealed types of Symbiodinium clade C specific to coral species. Types C1 and C3 (with C3z and C3i variants) were dominant in Acroporidae and C1 and C1c were the dominant types in Pocilloporidae. We also found 2 novel ITS2 types in S. hystrix and 1 novel ITS2 type of Symbiodinium in A. muricata. Some colonies of A. muricata and I. palifera were also associated with Symbiodinium A1. These results suggest that corals in the Chagos Archipelago host different assemblages of Symbiodinium types then their conspecifics from other locations in the Indian Ocean; and that future research will show whether these patterns in Symbiodinium genotypes may be due to local adaptation to specific conditions in the Chagos.
The geomorphic structure of the runoff peak
R. Rigon, P. D'Odorico,G. Bertoldi
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: This paper develops a theoretical framework to investigate the core dependence of peak flows on the geomorphic properties of river basins. Based on the theory of transport by travel times, and simple hydrodynamic characterization of floods, this new framework invokes the linearity and invariance of the hydrologic response to provide analytical and semi-analytical expressions for peak flow, time to peak, and area contributing to the peak runoff. These results are obtained for the case of constant-intensity hyetograph using the Intensity-Duration-Frequency (IDF) curves to estimate extreme flow values as a function of the rainfall return period. Results show that, with constant-intensity hyetographs, the time-to-peak is greater than rainfall duration and usually shorter than the basin concentration time. Moreover, the critical storm duration is shown to be independent of rainfall return period as well as the area contributing to the flow peak. The same results are found when the effects of hydrodynamic dispersion are accounted for. Further, it is shown that, when the effects of hydrodynamic dispersion are negligible, the basin area contributing to the peak discharge does not depend on the channel velocity, but is a geomorphic propriety of the basin. As an example this framework is applied to three watersheds. In particular, the runoff peak, the critical rainfall durations and the time to peak are calculated for all links within a network to assess how they increase with basin area.
The geomorphic structure of the runoff peak
R. Rigon,P. D'Odorico,G. Bertoldi
Hydrology and Earth System Sciences Discussions , 2011, DOI: 10.5194/hessd-8-1031-2011
Abstract: This paper develops a theoretical framework to investigate the core dependence of peak flows on the geomorphic properties of river basins. Based on the theory of transport by travel times, and simple hydrodynamic characterization of floods, this new framework invokes the linearity and invariance of the hydrologic response to provide analytical and semi-analitical expressions for peak flow, time to peak, and area contributing to the peak runoff. These results are obtained for the case of constant-intensity hyetograph using the Intensity-Duration-Frequency (IDF) curves to estimate extreme flow values as a function of the rainfall return period. Results show that, with constant-intensity hyetographs, the time-to-peak is greater than rainfall duration and usually shorter than the basin concentration time. Moreover, the critical storm duration is shown to be independent of rainfall return period. Further, it is shown that the basin area contributing to the peak discharge does not depend on the channel velocity, but is a geomorphic propriety of the basin. The same results are found when the effects of hydrodynamic dispersion are accounted for. As an example this framework is applied to three watersheds. In particular, the runoff peak, the critical rainfall durations and the time to peak are calculated for all links within a network to assess how they increase with basin area.
Reef bioconstructors of the Rocas Atoll, Equatorial South Atlantic
Marcelo de Oliveira Soares,Carlos Augusto Oliveira de Meirelles,Valesca Brasil Lemos
Biotemas , 2011,
Abstract: This study presents an analysis of reef bioconstructors at the Rocas Atoll, Brazil’s Northeast, sampled in January and February 2008. The results showed the presence of a community made up mainly of calcareous algae (Porolithon pachydermum, Sporolithon sp., Lithoporella sp., Lithophyllum sp.), corals (Siderastrea stellata, Favia gravida), vermetid mollusks (Dendropoma irregulare, Petaloconchus varians), and foraminifers (Homotrema rubrum) in the reef formation. This taxonomic survey shows the importance of a different species during the carbonate growth process of the only atoll in the Equatorial South Atlantic.
Links Between Z Sources and Atoll Sources  [PDF]
J. Wang,H. -K. Chang
Physics , 2012, DOI: 10.1017/S1743921312020261
Abstract: It is known that the Z and atoll sources are two typical types of neutron-star sources in low mass X-ray binaries (LMXBs), which present very different Q-$\nu$ relations of lower kHz QPOs. We propose that the Z and atoll sources are two different phases in the evolutionary track of neutron star in LMXBs, instead of two types of distinct sources.
On cubic Kummer towers of Garcia, Stichtenoth and Thomas type  [PDF]
M. Chara,R Toledano
Mathematics , 2014,
Abstract: In this paper we initiate the study of the class of cubic Kummer type towers considered by Garcia, Stichtenoth and Thomas in 1997 by classifying the asymptotically good ones in this class.
Object-Oriented France: The Philosophy of Tristan Garcia  [cached]
Graham Harman
continent. , 2012,
Abstract: Tristan Garcia has garnered significant attention over the last several years. Winner of the 2008 Prix de Flore for his debut novel, La meilleure part des hommes (Gallimard), Garcia has been a prolific writer and is an exciting new philosophical voice. Harman presents a lengthy discussion of Garcia's Forme et objet (PUF); an introduction to a text certain to significantly impact English-speaking thinkers for decades to come.
Estimating the Ground Water Resources of Atoll Islands  [PDF]
Ryan T. Bailey,John W. Jenson,Arne E. Olsen
Water , 2010, DOI: 10.3390/w2010001
Abstract: Ground water resources of atolls, already minimal due to the small surface area and low elevation of the islands, are also subject to recurring, and sometimes devastating, droughts. As ground water resources become the sole fresh water source when rain catchment supplies are exhausted, it is critical to assess current groundwater resources and predict their depletion during drought conditions. Several published models, both analytical and empirical, are available to estimate the steady-state freshwater lens thickness of small oceanic islands. None fully incorporates unique shallow geologic characteristics of atoll islands, and none incorporates time-dependent processes. In this paper, we provide a review of these models, and then present a simple algebraic model, derived from results of a comprehensive numerical modeling study of steady-state atoll island aquifer dynamics, to predict the ground water response to changes in recharge on atoll islands. The model provides an estimate thickness of the freshwater lens as a function of annual rainfall rate, island width, Thurber Discontinuity depth, upper aquifer hydraulic conductivity, presence or absence of a confining reef flat plate, and in the case of drought, time. Results compare favorably with published atoll island lens thickness observations. The algebraic model is incorporated into a spreadsheet interface for use by island water resources managers.
Geomorphic and archaeological -historical evidence for past ealihquakes in Greece
K. Gaki-Papanastassiou,D. Papanastassiou,H. Maroukian
Annals of Geophysics , 1996, DOI: 10.4401/ag-3994
Abstract: Geomorphic observations focused on landforms of marine and fluvial origin such as notches, beachrocks, stream channel shifts, alluvial terraces and knickpoints, when combined with historical and archaeological information are able to date seismic events that took place in the past in some places of the Peloponnesus. At thc Eastern Gulf of Corinth, a seismically active area, all the geomorphic observations fit quite well with the deformation field induced by the action of an offshore fault. At Mycenae, a seismically inactive area with no historical evidence of earthquakes, the archaeological information is the only evidence for past earthquakes while geomorphic data indicate the most probable activated fault. At Sparta, an area of low seismicity but with historical evidence of destructive earthquakes, the geomorphic evidence helps to identify the most likely ruptured fault. At Eliki, a seismically active area with well documented historical activity, the geomorphic data serve to define the causative fault.This paper shows that although historical and archaeological data provide evidence far the occurrence of past earthquakes and often their date, geomorphic observations must be used to identify the causative fault.
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