A protocol standard for heterogeneous telescope networks     

A. Allan  F. Hessman  K. Bischoff  M. Burgdorf  B. Cavanagh  D. Christian  N. Clay  R. Dickens  F. Economou  M. Fadavi  S. Fraser  T. Granzer  S. Grosvenor  T. Jenness  A. Koratkar  M. Lehner  C. Mottram  T. Naylor  E. Saunders  N. Solomos  I. Steele  G. Tuparev  T. Vestrand  R. White  S. Yost 《Astronomische Nachrichten》2006,327(8):744-750

The scientific need for a standard protocol permitting the exchange of generic observing services is rapidly escalating as more observatories adopt service observing as a standard operating mode and as more remote or robotic telescopes are brought on‐line. To respond to this need, we present the results of the first interoperability workshop for Heterogeneous Telescope Networks (HTN) held in Exeter. We present a draft protocol, designed to be independent of the specific instrumentation and software that controls the remote and/or robotic telescopes, allowing these telescopes to appear to the user with a unified interface despite any underlying architectural differences. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Energy ejection in the collapse of a cold spherical self-gravitating cloud     

M. Joyce  B. Marcos  F. Sylos Labini 《Monthly notices of the Royal Astronomical Society》2009,397(2):775-792

When an open system of classical point particles interacting by Newtonian gravity collapses and relaxes violently, an arbitrary amount of energy may, in principle, be carried away by particles which escape to infinity. We investigate here, using numerical simulations, how this released energy and other related quantities (notably the binding energy and size of the virialized structure) depend on the initial conditions, for the one-parameter family of starting configurations given by randomly distributing N cold particles in a spherical volume. Previous studies have established that the minimal size reached by the system scales approximately as   N ^1/3  , a behaviour which follows trivially when the growth of perturbations (which regularize the singularity of the cold collapse in the   N  →∞  limit) is assumed to be unaffected by the boundaries. Our study shows that the energy ejected grows approximately in proportion to   N ^1/3  , while the fraction of the initial mass ejected grows only very slowly with N , approximately logarithmically, in the range of N simulated. We examine in detail the mechanism of this mass and energy ejection, showing explicitly that it arises from the interplay of the growth of perturbations with the finite size of the system. A net lag of particles compared to their uniform spherical collapse trajectories develops first at the boundaries and then propagates into the volume during the collapse. Particles in the outer shells are then ejected as they scatter through the time-dependent potential of an already re-expanding central core. Using modified initial configurations, we explore the importance of fluctuations at different scales and discreteness (i.e. non-Vlasov) effects in the dynamics.  相似文献   

Sinking ships: conservation options for endemic taxa threatened by sea level rise     

Joyce Maschinski  Michael S. Ross  Hong Liu  Joe O��Brien  Eric J. von Wettberg  Kristin E. Haskins 《Climatic change》2011,107(1-2):147-167

Low-elevation islands face threats from sea level rise (SLR) and increased storm intensity. Evidence of endangered species?? population declines and shifts in vegetation communities are already underway in the Florida Keys. SLR predictions indicate large areas of these habitats may be eliminated in the next century. Using the Florida Keys as a model system, we present a process for evaluating conservation options for rare and endemic taxa. Considering species characteristics and habitat, we assess central issues that influence conservation options. We contrast traditional and controversial options for two animal and two plant species giving special emphasis to perceptions of ecological risk and safety from SLR and suggest courses of action. Multiple strategies will be required to spread extinction risk and will be effective for different time periods. Global climate change presents an uncertain, perhaps no-analog future that will challenge land managers and practitioners to re-evaluate equilibrium-state-conceived laws and policies not only for these taxa, but for many facing similar threats. To embrace conservation in a changing world will require a new dialogue that includes controversial ideas, a review of existing laws and policies, and preparation for the oncoming change.  相似文献   

The interaction of migrating grain boundaries with fluid inclusions in rock analogues: the effect of wetting angle and fluid inclusion velocity     

Joyce Schmatz  Oliver Schenk  Janos L. Urai 《Contributions to Mineralogy and Petrology》2011,162(1):193-208

The distribution of fluids in grain boundaries, fluid inclusion morphology and kinetics have important effects on the evolution of microstructure and transport properties and should be understood for correct interpretations for studies of thermobarometry and paleorheology. We compare results of in situ annealing experiments on rock analogues in the presence of different pore fluids in transmitted light: bischofite with saturated brine, camphor with ethanol, and camphor with ethylene glycol. The solid–liquid systems vary in terms of wettability and solubility, while homologous temperatures, strain rates, annealing times, and the initial textures are similar. In agreement with earlier work and theory, we observe different types of grain boundary–fluid inclusion interaction at sufficiently low grain boundary velocity such as drag and drop, necking, and the break up into arrays of smaller inclusions. In all three systems the maximum possible velocity of a fluid inclusion being dragged by a moving grain boundary is dependent on the fluid inclusion size. We interpret this to reflect the fluid inclusion mobility, and compare the trend with theoretical models which suggest that for all three systems the rate-limiting process is bulk diffusion and not surface diffusion or solution-precipitation.  相似文献   

The struggles for survival of street traders in Umtata,Transkei, 1980–89     

Joyce N. Nduna 《GeoJournal》1990,22(3):315-319

Within the broad theoretical context provided by debates on the subordination of the informal sector to capital, the paper investigates the struggles between communities of street traders and the municipal authorities of Umtata, capital city of Transkei. The study spans the period 1980–89. Themes of concern in the paper are objections to street traders and the adoption of repressive policies towards them, the resistance of street traders and the changing attitudes of the Transkei government and Umtata local authorities towards the operations of hawkers.  相似文献   

A new 40Ar/39Ar eruption age for the Mount Widderin volcano,Newer Volcanic Province,Australia, with implications for eruption frequency in the region     

E. L. Matchan  E. B. Joyce  D. Phillips 《Australian Journal of Earth Sciences》2016,63(2):175-186

The Mount Widderin shield volcano is located near Skipton, western Victoria, in the Western Plains subprovince of the monogenetic Pliocene–Holocene Newer Volcanic Province (NVP). Radiometric ages for lavas in the Hamilton–Skipton–Derrinallum area are few, owing to limited suitable outcrop for K–Ar or ⁴⁰Ar/³⁹Ar geochronology studies. Existing age constraints for flows in this area have been inferred from Regolith Landform Units (RLUs), complemented by a small number of K–Ar studies on ≥1 Ma flows. Although the RLU approach provides a valuable overview of relative eruption ages across the NVP, it is of limited use in eruption frequency studies. Additional radio-isotopic ages are required to refine age ranges for individual RLUs, and to validate previous assignment of individual flows to specific RLUs. We report a new, high-precision ⁴⁰Ar/³⁹Ar age of 389 ± 8 ka (2σ) for a Mount Widderin basalt sample. Based on this age and geomorphic observations, we propose that both the Widderin and Elephant lava flows be reassigned from the Eccles RLU to the Rouse RLU. We use the 389 ± 8 ka (2σ) age for Widderin, along with published K–Ar ages, to anchor a stratigraphic sequence of 15 individual flows in the Hamilton–Skipton–Derrinallum area, demonstrating that intermittent volcanism has occurred in this area from ≥3 Ma to ≤0.389 Ma. Within the limits of available data for the NVP, this time span of volcanic activity is second only to that of the Melbourne area. We consider the significance of the Widderin eruption age, in conjunction with published age constraints for maars and scoria cones of the Western Plains subprovince, building on previous studies that have focused solely on lava flow ages. The inclusion of the additional data weakens the argument for a decrease in volcanic activity after ca 0.9 Ma as implied by published ages for lava flows only. Additional detailed combined geochronology–geomorphology studies of lavas, scoria cones and maars in strategically selected small areas are advocated to better understand eruption frequency across the NVP.  相似文献   

Practices in disaster mitigation in the case of the 2015 Typhoon Koppu debris flows in Nueva Ecija,Philippines     

Llanes  Francesca V.  Eco  Rodrigo  Herrero  Tatum Miko  Briones  Jo Brianne Louise  Escape  Carmille Marie  Sulapas  Jolly Joyce  Galang  Jan Albert Macario  Ortiz  Iris Jill  Sabado  Jasmine May  Lagmay  Alfredo Mahar Francisco  Rodolfo  Kelvin 《Natural Hazards》2022,114(1):665-690

Natural Hazards - In October 2015, heavy rains brought by Typhoon Koppu generated landslides and debris flows in the municipalities of Bongabon, Laur, and Gabaldon in Nueva Ecija province....  相似文献   

Reconstructing past fire regimes: methods,applications, and relevance to fire management and conservation     

Marco Conedera  Willy Tinner  Christophe Neff  Manfred Meurer  Angela F. Dickens  Patrik Krebs 《Quaternary Science Reviews》2009,28(5-6):555-576

Biomass burning and resulting fire regimes are major drivers of vegetation changes and of ecosystem dynamics. Understanding past fire dynamics and their relationship to these factors is thus a key factor in preserving and managing present biodiversity and ecosystem functions. Unfortunately, our understanding of the disturbance dynamics of past fires is incomplete, and many open questions exist relevant to these concepts and the related methods. In this paper we describe the present status of the fire-regime concept, discuss the notion of the fire continuum and related proxies, and review the most important existing approaches for reconstructing fire history at centennial to millennial scales. We conclude with a short discussion of selected directions for future research that may lead to a better understanding of past fire-regime dynamics. In particular, we suggest that emphasis should be laid on (1) discriminating natural from anthropogenic fire-regime types, (2) improving combined analysis of fire and vegetation reconstructions to study long-term fire ecology, and (3) overcoming problems in defining temporal and spatial scales of reference, which would allow better use of past records to gain important insights for landscape, fire and forest management.  相似文献   

Persistent blooms of surf diatoms along the pacific coast,U.S.A.: I. Physical characteristics of the coastal region in relation to the distribution and abundance of the species     

Janice Lee Garver  Joyce Lewin 《Estuarine, Coastal and Shelf Science》1981,12(2):217-229

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Comparison of the Climate during Marine Isotope Stage 9 and 11 Inferred from a Speleothem Isotope Record from Northern Norway     

Ida M. Berstad  Joyce Lundberg  Stein-Erik Lauritzen  Henriette C. Linge 《Quaternary Research》2002,58(3):361

A stalagmite from northern Norway is dated with 12 thermal ionization mass spectrometry U-Th dates, and at least four separate growth periods are identified that correspond with marine isotope stages 9, 11, 13, and probably 15. The calcite is tested for isotopic equilibrium with the Hendy test. Oxygen isotope measurements on 231 subsamples on a vertical transect are used as a paleotemperature proxy. The detailed isotopic record from MIS 9 show apparent similarities to a Holocene record from the same cave, both in the climatic evolution and the overall temperatures: both show temperature oscillations changing from high-frequency, low-amplitude cycles in the beginning of the interglacial period to lower frequency, higher amplitude cycles in the later part of the interglacial period. The isotope record from MIS 11 shows a distinct isotopic event toward heavier values. The isotopic record together with the porous, humus-rich calcite are interpreted as indicating a warmer than present interglacial period with several episodes of heavy rainfall.  相似文献