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Search Results: 1 - 10 of 481583 matches for " Paul A. Tyler "
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BIOGEOGRAPHY OF DEEP-WATER CHEMOSYNTHETIC ECOSYSTEMS (CHESS): EXPLORING THE SOUTHERN OCEANS
Ramírez Llodra,Eva; Tyler,Paul A; German,Christopher R;
Gayana (Concepción) , 2003, DOI: 10.4067/S0717-65382003000200006
Abstract: the vast majority of the mid-ocean ridge system and of the continental margins around the globe have not yet been explored. a relatively small number of vent and seep sites have been analysed and are the focus of long-term research programmes. however, the exploration of new areas will certainly provide the discovery of new vent and seep sites. furthermore, the study of these key locations will lead to the description of new species and improve our understanding of the abundance, diversity, and distribution of species from chemosynthetically-driven systems around the world's oceans. it is the aim of chess to develop an exploration field phase to discover new deep-water hydrothermal vents and cold seeps at key locations, to describe their fauna, and to study the processes driving these ecosystems. the main objective is to obtain a thorough understanding of the biogeography of chemosynthetic ecosystems at a global scale. this goal can only be reached through international cooperation, which will be coordinated by the chess scientific steering committee. the southern oceans are the less studied regions for deep-water chemosynthetic sites. mainly, the indian ocean ridges, the southern mid-atlantic ridge, the east scotia ridge, and the chile rise for vents; and the continental margins of brazil, peru, chile and africa for seeps, are crucial for the biogeographic puzzle of chemosynthetic systems.
BIOGEOGRAPHY OF DEEP-WATER CHEMOSYNTHETIC ECOSYSTEMS (CHESS): EXPLORING THE SOUTHERN OCEANS BIOGEOGRAFIA DE ECOSISTEMAS QUIMIOSINTETICOS PROFUNDOS (ChEss): EXPLORANDO EL HEMISFERIO SUR
Eva Ramírez Llodra,Paul A Tyler,Christopher R German
Gayana (Concepción) , 2003,
Abstract: The vast majority of the mid-ocean ridge system and of the continental margins around the globe have not yet been explored. A relatively small number of vent and seep sites have been analysed and are the focus of long-term research programmes. However, the exploration of new areas will certainly provide the discovery of new vent and seep sites. Furthermore, the study of these key locations will lead to the description of new species and improve our understanding of the abundance, diversity, and distribution of species from chemosynthetically-driven systems around the world's oceans. It is the aim of ChEss to develop an exploration field phase to discover new deep-water hydrothermal vents and cold seeps at key locations, to describe their fauna, and to study the processes driving these ecosystems. The main objective is to obtain a thorough understanding of the biogeography of chemosynthetic ecosystems at a global scale. This goal can only be reached through international cooperation, which will be coordinated by the ChEss scientific steering committee. The southern oceans are the less studied regions for deep-water chemosynthetic sites. Mainly, the Indian Ocean Ridges, the southern Mid-Atlantic Ridge, the East Scotia Ridge, and the Chile Rise for vents; and the continental margins of Brazil, Peru, Chile and Africa for seeps, are crucial for the biogeographic puzzle of chemosynthetic systems. La mayor parte del sistema de dorsales oceánicas y los márgenes continentales de nuestro planeta todavía no han sido explorados. Un número limitado de fuentes hidrotermales y frías han sido estudiadas y son el objeto de programas de investigación a largo término. Sin embargo, la exploración de nuevas áreas quimiosintéticas llevará sin lugar a dudas a descubrir nuevas fuentes hidrotermales y coladuras frías. Además, el estudio de estas localidades llevará a descripciones de nuevas especies, así como a un mayor y más completo conocimiento sobre la abundancia, la diversidad y la distribución de especies de sistemas quimiosintéticos, alrededor de los oceános del mundo. Uno de los componentes principales de ChEss es un programa de campo a largo término para el descubrimiento y la exploración de nuevas fuentes hidrotermales y surgencias frías en áreas claves, así como la descripción de su fauna y el estudio de los procesos que dirigen a dichas comunidades. El objetivo principal es obtener un conocimiento sólido sobre la biogeografía de ecosistemas quimiosintéticos de profundidad a escala global. Este objetivo sólo se puede alcanzar a través de cooperación internacional, la
Spatial Variation in the Population Structure and Reproductive Biology of Rimicaris hybisae (Caridea: Alvinocarididae) at Hydrothermal Vents on the Mid-Cayman Spreading Centre
Verity Nye, Jonathan T. Copley, Paul A. Tyler
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0060319
Abstract: The dynamics and microdistribution of faunal assemblages at hydrothermal vents often reflect the fine-scale spatial and temporal heterogeneity of the vent environment. This study examined the reproductive development and population structure of the caridean shrimp Rimicaris hybisae at the Beebe and Von Damm Vent Fields (Mid-Cayman Spreading Centre, Caribbean) using spatially discrete samples collected in January 2012. Rimicaris hybisae is gonochoric and exhibits iteroparous reproduction. Oocyte size-frequency distributions (21-823 μm feret diameters) varied significantly among samples. Embryo development was asynchronous among females, which may result in asynchronous larval release for the populations. Specimens of R. hybisae from the Von Damm Vent Field (2294 m) were significantly larger than specimens from the Beebe Vent Field. Brooding females at Von Damm exhibited greater size-specific fecundity, possibly as a consequence of a non-linear relationship between fecundity and body size that was consistent across both vent fields. Samples collected from several locations at the Beebe Vent Field (4944–4972 m) revealed spatial variability in the sex ratios, population structure, size, and development of oocytes and embryos of this mobile species. Samples from the Von Damm Vent Field and sample J2-613-24 from Beebe Woods exhibited the highest frequencies of ovigerous females and significantly female-biased sex ratios. Environmental variables within shrimp aggregations may influence the distribution of ovigerous females, resulting in a spatially heterogeneous pattern of reproductive development in R. hybisae, as found in other vent taxa.
Deep-Water Chemosynthetic Ecosystem Research during the Census of Marine Life Decade and Beyond: A Proposed Deep-Ocean Road Map
Christopher R. German,Eva Ramirez-Llodra,Maria C. Baker,Paul A. Tyler
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0023259
Abstract: The ChEss project of the Census of Marine Life (2002–2010) helped foster internationally-coordinated studies worldwide focusing on exploration for, and characterization of new deep-sea chemosynthetic ecosystem sites. This work has advanced our understanding of the nature and factors controlling the biogeography and biodiversity of these ecosystems in four geographic locations: the Atlantic Equatorial Belt (AEB), the New Zealand region, the Arctic and Antarctic and the SE Pacific off Chile. In the AEB, major discoveries include hydrothermal seeps on the Costa Rica margin, deepest vents found on the Mid-Cayman Rise and the hottest vents found on the Southern Mid-Atlantic Ridge. It was also shown that the major fracture zones on the MAR do not create barriers for the dispersal but may act as trans-Atlantic conduits for larvae. In New Zealand, investigations of a newly found large cold-seep area suggest that this region may be a new biogeographic province. In the Arctic, the newly discovered sites on the Mohns Ridge (71°N) showed extensive mats of sulfur-oxidisng bacteria, but only one gastropod potentially bears chemosynthetic symbionts, while cold seeps on the Haakon Mossby Mud Volcano (72°N) are dominated by siboglinid worms. In the Antarctic region, the first hydrothermal vents south of the Polar Front were located and biological results indicate that they may represent a new biogeographic province. The recent exploration of the South Pacific region has provided evidence for a sediment hosted hydrothermal source near a methane-rich cold-seep area. Based on our 8 years of investigations of deep-water chemosynthetic ecosystems worldwide, we suggest highest priorities for future research: (i) continued exploration of the deep-ocean ridge-crest; (ii) increased focus on anthropogenic impacts; (iii) concerted effort to coordinate a major investigation of the deep South Pacific Ocean – the largest contiguous habitat for life within Earth's biosphere, but also the world's least investigated deep-ocean basin.
SOUSA: the Swift Optical/Ultraviolet Supernova Archive
Peter J. Brown,Alice A. Breeveld,Stephen Holland,Paul Kuin,Tyler Pritchard
Physics , 2014, DOI: 10.1007/s10509-014-2059-8
Abstract: The Ultra-Violet Optical Telescope on the Swift spacecraft has observed hundreds of supernovae, covering all major types and most subtypes. Here we introduce the Swift Optical/Ultraviolet Supernova Archive (SOUSA), which will contain all of the supernova images and photometry. We describe the observation and reduction procedures and how they impact the final data. We show photometry from well-observed examples of most supernova classes, whose absolute magnitudes and colors may be used to infer supernova types in the absence of a spectrum. A full understanding of the variety within classes and a robust photometric separation of the groups requires a larger sample, which will be provided by the final archive. The data from the existing Swift supernovae are also useful for planning future observations with Swift as well as future UV observatories.
The equation of state in two-, three-, and four-color QCD at non-zero temperature and density
Tyler Gorda,Paul Romatschke
Physics , 2014, DOI: 10.1103/PhysRevD.92.014019
Abstract: We calculate the equation of state at non-zero temperature and density from first principles in two-, three- and four-color QCD with two fermion flavors in the fundamental and two-index, antisymmetric representation. By matching low-energy results (from a `hadron resonance gas') to high-energy results from (resummed) perturbative QCD, we obtain results for the pressure and trace anomaly that are in quantitative agreement with full lattice-QCD studies for three colors at zero chemical potential. Our results for non-zero chemical potential at zero temperature constitute predictions for the equation of state in QCD-like theories that can be tested by traditional lattice studies for two-color QCD with two fundamental fermions and four-color QCD with two two-index, antisymmetric fermions. We find that the speed of sound squared at zero temperature can exceed one third, which may be relevant for the phenomenology of high-mass neutron stars.
Precision studies of v_n fluctuations
Tyler Gorda,Paul Romatschke
Physics , 2014, DOI: 10.1103/PhysRevC.90.054908
Abstract: The power spectrum of heavy ion collisions is investigated by studying initial state fluctuations on top of a smooth hydrodynamic flow. In particular, the stability of the location of the first minimum of the power spectrum and the dependence of the hydrodynamic response v_n / epsilon_n on n and on eta / s are discussed. In our study we develop a new Green's function method for the analytic hydrodynamic flow by S. Gubser and make use of a fully non-linear hydrodynamics code. We find that there will be no well-defined first minimum of the response for n < 10, due to the fact that all minima in that region are found to be sensitive to the location of the initial perturbations. Also, we find that the often proposed form of the hydrodynamical response, that ln ( v_n / epsilon_n ) depend quadratically on n and linearly on eta / s, should not hold once many events have been averaged over.
Family Conflict Resolution: Its Measurement and Relationship with Family Conflict and Psychological Adjustment  [PDF]
P. Tyler Roskos, Paul J. Handal, Megan E. Ubinger
Psychology (PSYCH) , 2010, DOI: 10.4236/psych.2010.15046
Abstract: Based on family conflict literature, there is a need for the development of a measure of family conflict resolution. This study aimed to develop items based on established instruments and rationally construct new items in order to pilot a measure of family conflict resolution. Preliminary reliability and validity data were obtained using a sample of young adults. Results indicate that the proposed measure of conflict resolution produced valid factor analytic solutions, adequate internal consistency, and construct validity. The results of this study also revealed avoidance of conflict as a factor that is related to adjustment. Future research into conflict avoidance as a salient contributor to psychological adjustment appears warranted.
A Picture on the Wall: Innovative Mapping Reveals Cold-Water Coral Refuge in Submarine Canyon
Veerle A. I. Huvenne, Paul A. Tyler, Doug G. Masson, Elizabeth H. Fisher, Chris Hauton, Veit Hühnerbach, Timothy P. Le Bas, George A. Wolff
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028755
Abstract: Cold-water corals are azooxanthellate species found throughout the ocean at water depths down to 5000 m. They occur in patches, reefs or large mound structures up to 380 m high, and as ecosystem engineers create important habitats for a diverse fauna. However, the majority of these habitats are now within reach of deep-sea bottom trawling. Many have been severely damaged or are under threat, despite recent protection initiatives. Here we present a cold-water coral habitat type that so far has been overlooked – quite literally – and that has received minimal impact from human activities. Vertical and overhanging cliffs in deep-sea canyons, revealed using an innovative approach to marine habitat mapping, are shown to provide the perfect substratum for extensive cold-water coral-based communities. Typical canyon-related processes, including locally enhanced internal tides and focussed downslope organic carbon transport, provide favourable environmental conditions (current regime, food input) to sustain the communities, even outside the optimal depth and density envelopes reported elsewhere in the NE Atlantic. Our findings show that deep-sea canyons can form natural refuges for faunal communities sensitive to anthropogenic disturbance, and have the potential to fulfil the crucial role of larval sources for the recolonisation of damaged sites elsewhere on the margin.
Microdistribution of Faunal Assemblages at Deep-Sea Hydrothermal Vents in the Southern Ocean
Leigh Marsh, Jonathan T. Copley, Veerle A. I. Huvenne, Katrin Linse, William D. K. Reid, Alex D. Rogers, Christopher J. Sweeting, Paul A. Tyler
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048348
Abstract: Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal vents, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered vent fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of vent biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal activity in a vent field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal activity, and a mosaic image of >250 m2 of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from vent sources and peak temperatures. Assemblages closest to vent sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m?2), followed by a peltospiroid gastropod (>1,500 individuals m?2), eolepadid barnacle (>1,500 individuals m?2), and carnivorous actinostolid anemone (>30 individuals m?2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of activity suggests a possible successional sequence for vent fauna in this new biogeographic province. An increase in δ34S values of primary consumers with distance from vent sources, and variation in their δ13C values also indicate possible zonation of nutritional modes of the vent fauna. By using ROV videography to obtain a high-resolution representation of a vent environment over a greater extent than previous studies, these results provide a baseline for determining temporal change and investigations of processes structuring faunal assemblages at Southern Ocean vents.
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