Acute toxicity of copper to sea catfish     

Craig W. Steele 《Marine pollution bulletin》1983,14(5):168-170

Sea catfish (Arius felis) were exposed to aqueous solutions of reagent grade cupric chloride in artificial seawater ($\text{30.0±2.0‰}$, 21–23°C) in four static bioassays. The 24, 48, 72 and 96 h LC₅₀ were calculated and found to be 5.43, 4.17, 3.57 and 2.40 mg l.^?1 copper, respectively. Experimental concentrations of copper producing subtle behavioral changes in this species correspond to less than 0.3% of the 72 h LC₅₀. Based on this comparison with literature values, a new, maximum ‘safe’ concentration for copper in marine waters of 0.01 mg l.^?1 is proposed.  相似文献   

Comparison of the behavioural and acute toxicity of copper to sheepshead,Atlantic croaker and pinfish     

Craig W Steele 《Marine pollution bulletin》1983,14(11):425-428

Sheepshead (Archosargus probatocephalus), Atlantic croaker (Micropogon undulatus) and pinfish (Lagodon rhomboides) were each exposed to aqueous solutions of reagent grade cupric chloride in artificial seawater in four static bioassays. The 24, 48, 72 and 96-h TL_m were determined to be, respectively, 4.17, 3.02, 2.19 and 1.14 mg Cu²⁺·I^?1 for sheepshead, 9.15, 7.55, 7.20 and 5.66 mg Cu²⁺·I^?1 for croaker, and 7.33, 4.43, 4.14 and 2.75 mg Cu²⁺·I^?1 for pinfish. These results are compared with literature values of experimental concentrations of copper producing subtle behavioural changes in these species.  相似文献   

Telescope and instrument robotization at Dome C     

K. G. Strassmeier  K. Agabi  L. Agnoletto  A. Allan  M. I. Andersen  W. Ansorge  F. Bortoletto  R. Briguglio  J.‐T. Buey  S. Castellini  V. Coud du Foresto  L. Dam  H. J. Deeg  C. Eiroa  G. Durand  D. Fappani  M. Frezzotti  T. Granzer  A. Grschke  H. J. Krcher  R. Lenzen  A. Mancini  C. Montanari  A. Mora  A. Pierre  O. Pirnay  F. Roncella  F.‐X. Schmider  I. Steele  J. W. V. Storey  N. F. H. Tothill  T. Travouillon  L. Vittuari  M. Weber 《Astronomische Nachrichten》2007,328(6):451-474

This article reviews the situation for robotization of telescopes and instruments at the Antarctic station Concordia on Dome C. A brain‐storming meeting was held in Tenerife in March 2007 from which this review emerged.We describe and summarize the challenges for night‐time operations of various astronomical experiments at conditions “between Earth and Space” and conclude that robotization is likely a prerequisite for continuous astronomical data taking during the 2000‐hour night at Dome C. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Identifying granite sources by SHRIMP U-Pb zircon geochronology: an application to the Lachlan foldbelt   总被引：24，自引：1，他引：23  

Sue Keay  David Steele  William Compston 《Contributions to Mineralogy and Petrology》1999,137(4):323-341

The potential genetic link between granites and their host sediments can be assessed using zircon age inheritance patterns. In the Lachlan fold belt, southeastern Australia, granites and associated high-grade metasedimentary rocks intrude low-grade Ordovician country rock. This relationship is well-exposed in the Tallangatta region, northeast Victoria (part of the Wagga-Omeo Metamorphic Complex). In this region granites (two I-types and two S-types) have intruded during the mid-late Silurian between approximately 410–430 Ma based on the ages of magmatic zircons. The age spectra for inherited zircons from the granites have been compared with those of detrital zircons from the enclosing low- and high-grade metasediments. In broad terms, both for detrital zircons in all four sediments and for inherited zircons in three of the four granites, the dominant ages are early Paleozoic and Late Precambrian, with sporadic older Precambrian ages extending up to 3.5 Ga. The ages of the youngest detrital zircons from the low-grade Lockhart and Talgarno terranes limit the time of sedimentation to ca. 466 Ma or younger. The youngest detrital zircons from two samples of the high-grade Gundowring terrane are 473 Ma, making these sediments Ordovician or younger, not Cambrian as originally suggested. However, the individual age spectra for the four selected metasediments are not well matched when closely examined. The age spectra of the inherited zircons in the granites also do not adequately match those in any of the metasediments. Thus, the metasediments might not be representative of the actual source rocks of the granites. While the exact source of the granites cannot be identified from the analysed samples, the existence of a large population of ca. 495 Ma inherited zircon grains in the S-type granites requires that the granite source contains a significant proportion of Cambrian or younger material. This does not preclude the existence of a Precambrian basement to the Lachlan fold belt but indicates that at the level of S-type magma generation, a Cambrian and/or younger protolith is required. Received: 28 August 1998 / Accepted: 7 July 1999  相似文献   

Use of advanced directional wave spectra analysis methods     

M. D. Earle  K. E. Steele  D. W. C. Wang 《Ocean Engineering》1999,26(12):2853

Frequency-dependent cross-spectral parameters for pitch-roll buoy data and parameters that describe directional wave spectra based on a directional Fourier series are developed by the National Data Buoy Center (NDBC) and other organizations that collect wave data. The World Meteorological Organization (WMO) specifies wave data product formats in its Wave Observation (FM 65 WAVEOB) code. Other organizations, such as the US Army Corps of Engineers Field Wave Gaging Program (FWGP), have similar specifications. A directional Fourier series has poor directional resolution compared with advanced methods such as those based on maximum likelihood and maximum entropy. Transformations are developed for applying the advanced methods and working with directional wave information stored in the WMO's FM 65 WAVEOB code, the FWGP's Wave Data Analysis Standard (WDAS) format, and similar codes and formats. Using the transformations, a directional Fourier series expansion method, a Maximum Likelihood Method (MLM), and a Maximum Entropy Method (MEM) are each applied to 115 sets of NDBC directional wave data. The MEM and MLM provide better directional resolution, but the MEM produces artificial double peaks. There are considerable differences for the three used methods. The developed transformation equations enable wave data users to apply the method that best suits their applications.  相似文献   

IZ photometry of L dwarfs and the implications for brown dwarf surveys     

I. A. Steele  L. Howells 《Monthly notices of the Royal Astronomical Society》2000,313(4):L43-L45

The I − Z colour has recently been shown to be a good temperature indicator for M dwarfs. We present the first IZ photometry of a small sample of L dwarfs ranging in spectral type from L0.5V to L6.0V. We find that the I − Z colour is not a good temperature indicator for objects between L1V and L5V, such objects having colours that overlap with mid M dwarfs. We attribute this to the reduction in the strength of the TiO and VO bands in the L dwarfs, which are the dominant opacity source in the I band for late M dwarfs. Beyond L5V, I − Z appears to be a reasonable indicator. This has important implications for the planning of optical surveys for cool objects in clusters and the field. For example, I − Z will cease to be a good method of identifying brown dwarfs in the Pleiades below around 0.04 M_⊙, and at around 0.075 M_⊙ in the Hyades and Praesepe.  相似文献   

RoboNet‐II: Follow‐up observations of microlensing events with a robotic network of telescopes     

Y. Tsapras  R. Street  K. Horne  C. Snodgrass  M. Dominik  A. Allan  I. Steele  D.M. Bramich  E.S. Saunders  N. Rattenbury  C. Mottram  S. Fraser  N. Clay  M. Burgdorf  M. Bode  T.A. Lister  E. Hawkins  J.P. Beaulieu  P. Fouqu  M. Albrow  J. Menzies  A. Cassan  D. Dominis‐Prester 《Astronomische Nachrichten》2009,330(1):4-11

RoboNet‐II uses a global network of robotic telescopes to perform follow‐up observations of microlensing events in the Galactic Bulge. The current network consists of three 2 m telescopes located in Hawaii and Australia (owned by Las Cumbres Observatory) and the Canary Islands (owned by Liverpool John Moores University). In future years the network will be expanded by deploying clusters of 1 m telescopes in other suitable locations. A principal scientific aim of the RoboNet‐II project is the detection of cool extra‐solar planets by the method of gravitational microlensing. These detections will provide crucial constraints to models of planetary formation and orbital migration. RoboNet‐II acts in coordination with the PLANET microlensing follow‐up network and uses an optimization algorithm (“web‐PLOP”) to select the targets and a distributed scheduling paradigm (eSTAR) to execute the observations. Continuous automated assessment of the observations and anomaly detection is provided by the ARTEMiS system (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search): A possible expert‐system based cooperative effort to hunt for planets of Earth mass and below     

M. Dominik  K. Horne  A. Allan  N.J. Rattenbury  Y. Tsapras  C. Snodgrass  M.F. Bode  M.J. Burgdorf  S.N. Fraser  E. Kerins  C.J. Mottram  I.A. Steele  R.A. Street  P.J. Wheatley  &#x;. Wyrzykowski 《Astronomische Nachrichten》2008,329(3):248-251

The technique of gravitational microlensing is currently unique in its ability to provide a sample of terrestrial exoplanets around both Galactic disk and bulge stars, allowing to measure their abundance and determine their distribution with respect to mass and orbital separation. Thus, valuable information for testing models of planet formation and orbital migration is gathered, constituting an important piece in the puzzle for the existence of life forms throughout the Universe. In order to achieve these goals in reasonable time, a well‐coordinated effort involving a network of either 2m or 4×1m telescopes at each site is required. It could lead to the first detection of an Earth‐mass planet outside the Solar system, and even planets less massive than Earth could be discovered. From April 2008, ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) is planned to provide a platform for a three‐step strategy of survey, follow‐up, and anomaly monitoring. As an expert system embedded in eSTAR (e‐Science Telescopes for Astronomical Research), ARTEMiS will give advice for follow‐up based on a priority algorithm that selects targets to be observed in order to maximize the expected number of planet detections, and will also alert on deviations from ordinary microlensing light curves by means of the SIGNALMEN anomaly detector. While the use of the VOEvent (Virtual Observatory Event) protocol allows a direct interaction with the telescopes that are part of the HTN (Heterogeneous Telescope Networks) consortium, additional interfaces provide means of communication with all existing microlensing campaigns that rely on human observers. The success of discovering a planet by microlensing critically depends on the availability of a telescope in a suitable location at the right time, which can mean within 10 min. To encourage follow‐up observations, microlensing campaigns are therefore releasing photometric data in real time. On ongoing planetary anomalies, world‐wide efforts are being undertaken to make sure that sufficient data are obtained, since there is no second chance. Real‐time modelling offers the opportunity of live discovery of extra‐solar planets, thereby providing “Science live to your home”. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Evaluation of cell lysis procedures and use of a micro fluidic system for an automated DNA-based cell identification in interplanetary missions     

J.A. Hall  E. Felnagle  M. Fries  S. Spearing  L. Monaco  A Steele   《Planetary and Space Science》2006,54(15):1600-1611

A Modular Assay System for Solar System Exploration (MASSE) is being developed to include sample handling, pre-treatment, separation and analysis of biological target compounds by both DNA and protein microarrays. To better design sensitive and accurate initial upstream sample handling of the MASSE instrument, experiments investigating the sensitivity and potential extraction bias of commercially available DNA extraction kits between classes of environmentally relevant prokaryotes such as gram-negative bacteria (Escherichia coli), gram-positive bacteria (Bacillus megatarium), and Archaea (Haloarcula marismortui) were performed. For extractions of both planktonic cultures and spiked Mars simulated regolith, FTA^® paper demonstrated the highest sensitivity, with detection as low as 1×10¹ cells and 3.3×10² cells, respectively. In addition to the highest sensitivity, custom modified application of FTA^® paper extraction protocol is the simplest in terms of incorporation into MASSE and displayed little bias in sensitivity with respect to prokaryotic cell type. The implementation of FTA paper for environmental microbiology investigations appears to be a viable and effective option potentially negating the need for other pre-concentration steps such as filtration and negating concerns regarding extraction efficiency of cells. In addition to investigations on useful technology for upstream sample handling in MASSE, we have also evaluated the potential for μTAS to be employed in the MASSE instrument by employing proprietary lab-on-a-chip development technology to investigate the potential for microfluidic cell lysis of different prokaryotic cells employing both chemical and biological lysis agents. Real-time bright-field microscopy and quantitative PMT detection indicated that that gram positive, gram negative and archaeal cells were effectively lyzed in a few seconds using the microfluidic chip protocol developed. This included employing a lysis buffer with components including lysozyme, Protease, Proteinase K, Tween-20 and TritonX-100. The effectiveness of antibiotics and other chemical lysis agents were also screened and demonstrated partial effectiveness on all three cell types. This work demonstrates a step wise approach to evaluating the efficacy and sensitivity of commercial macro-scale technology and state-of-the-art developmental microfluidic technology under consideration for incorporation into the remotely operated MASSE instrument currently under development at the Carnegie Institution of Washington.  相似文献   

Finding benchmark brown dwarfs to probe the substellar initial mass function as a function of time     

D. J. Pinfield  H. R. A. Jones  P. W. Lucas  T. R. Kendall  S. L. Folkes  A. C. Day-Jones  R. J. Chappelle  I. A. Steele 《Monthly notices of the Royal Astronomical Society》2006,368(3):1281-1295

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