The Type IIn supernova 1994W: evidence for the explosive ejection of a circumstellar envelope     

Nikolai N. Chugai  Sergei I. Blinnikov  Robert J. Cumming  Peter Lundqvist  Angela Bragaglia  Alexei V. Filippenko  Douglas C. Leonard  Thomas Matheson  Jesper Sollerman 《Monthly notices of the Royal Astronomical Society》2004,352(4):1213-1231

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A Very Small Array search for the extended Sunyaev–Zel''dovich effect in the Corona Borealis supercluster     

Ricardo Génova-Santos  José Alberto Rubiño-Martín  Rafael Rebolo †  Kieran Cleary ‡  Rod D. Davies  Richard J. Davis  Clive Dickinson §  Nelson Falcón ‡‡  Keith Grainge  Carlos M. Gutiérrez  Michael P. Hobson  Michael E. Jones ¶  Rüdiger Kneissl &#;  Katy Lancaster  Carmen P. Padilla-Torres  Richard D. E. Saunders  Paul F. Scott  Angela C. Taylor ¶  Robert A. Watson †† 《Monthly notices of the Royal Astronomical Society》2005,363(1):79-92

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First results from the Very Small Array – I. Observational methods     

Robert A. Watson  Pedro Carreira  Kieran Cleary  Rod D. Davies  Richard J. Davis  Clive Dickinson  Keith Grainge †  Carlos M. Gutiérrez  Michael P. Hobson  Michael E. Jones  Rüdiger Kneissl  Anthony Lasenby  Klaus Maisinger  Guy G. Pooley  Rafael Rebolo  José Alberto Rubiño-Martin ‡  Ben Rusholme §  Richard D. E. Saunders  Richard Savage  Paul F. Scott  An&#;e Slosar  Pedro J. Sosa Molina  Angela C. Taylor  David Titterington  Elizabeth Waldram  Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065

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Survival under chronic stress from sediment load: spatial patterns of hard coral communities in the southern islands of Singapore     

Dikou A  van Woesik R 《Marine pollution bulletin》2006,52(1):7-21

Six reef sites were chosen along the west coasts of Singapore's southern islands, to: (1) quantitatively assess and compare coral community composition and structure, and recruitment rates, (2) assess the relationship between the aforementioned patterns and the environmental conditions, and (3) provide insights on potential processes that incorporate history at these study sites. Chronic exposure to high sediment load was the most obvious form of anthropogenic stress. Recruitment rates on ceramic tiles were low (1.4+/-1.0-20+/-14.7 recruits m(-2)year(-1)) but decreased towards the main island of Singapore as did hard coral cover and coral density. Coral fauna consisted of genera generally found in deeper waters (e.g., fungiids, foliose Oxypora, Leptoseris, and Echinopora) or those well adapted to turbid waters (e.g., Porites, Pectinia, Leptastrea, Montipora). Light extinction coefficient (K) and % live coral cover (%LCC) showed a strong and inverse curvilinear relationship (%LCC=13.60 *K(-3.40)). Similarly, the rate of sediment deposition (DFSPM) (Recruitment rate, RR=1.51-0.17 *DFSPM) and water clarity (RR=3.56-2.92 *K) exhibited strong and inverse relationships with recruitment rates. Although measured levels of the down-ward flux of suspended particulate matter and suspended solids were well within "normal" levels recorded in the literature, it was the proportion of benthic space, generic coral composition, and site history that offered compelling evidence of chronic exposure to increased sediment load. Clearly a reduction in both water clarity and live-coral cover has taken place since monitoring efforts began in the early 1970s, in fact coral cover has more than halved at all sites examined since the 1980s and benthic space was predominantly occupied by dead corals covered with sediment and filamentous algae.  相似文献   

Use of biliary PAH metabolites as a biomarker of pollution in fish from the Baltic Sea   总被引：2，自引：0，他引：2  

Vuorinen PJ  Keinänen M  Vuontisjärvi H  Barsiene J  Broeg K  Förlin L  Gercken J  Kopecka J  Köhler A  Parkkonen J  Pempkowiak J  Schiedek D 《Marine pollution bulletin》2006,53(8-9):479-487

During field campaigns of the BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems) in 2001-2002, metabolites of polycyclic aromatic hydrocarbons (PAHs) were determined in bile samples from three fish species, flounder (Platichthys flesus), perch (Perca fluviatilis) and eelpout (Zoarces viviparus), from four separate areas in the Baltic Sea. Two determination methods were applied: fixed wavelength fluorescence (FF) for pyrene-type metabolites and high-performance liquid chromatography with fluorescence detection (HPLC). There was a good correlation between the FF method and 1-OH pyrene determined by HPLC. Normalisation of the FF data for absorbance at 380 nm or bile protein concentrations greatly increased variance in one third and decreased it in two thirds of the cases and resulted in a loss of significant differences (protein normalisation) between the sampling stations, but normalisation of the HPLC data had little effect on the results. The biliary PAH metabolite content was usually higher in males than in females. In perch and eelpout the biliary PAH contents were at similar levels, whereas in flounder the levels were lower. The sampling areas arranged in decreasing order of biliary PAH contents were: Wismar Bay > Gulf of Gdansk > Lithuanian coast > Kvadofj?rden (reference area). It is concluded that FF with un-normalised data is a reliable and simple method for monitoring purposes and only one sex of a selected species should be used.  相似文献   

Effect of growth on active biomonitoring with terrestrial mosses     

J. Angel Fernández  Angela Ares  Ana Rey-Asensio  Alejo Carballeira  Jesus R. Aboal 《Journal of Atmospheric Chemistry》2009,63(1):1-11

The effects of growth of autoirrigated, shaded transplants of Pseudoscleropodium purum on the quantification of tissue concentrations of Cd, Cu, Hg, V and Zn, were investigated in 4 exposure periods, each of 56 days, at 7 sampling sites (contaminated and uncontaminated). Concentrations of the elements in the basal portions of the moss shoots were compared with the concentrations in the portions of the shoots that grew during the exposure period. Mercury and V were present at lower concentrations in the new portions of the shoots than in the basal portions, whereas the opposite was true for Cd, Cu and Zn. The magnitude of error introduced by growth was not negligible, and in some cases was higher than 40%, relative to the results obtained by analysis of the whole shoot. Devitalization of moss prior to its use as transplant material is recommended to avoid growth of the plant during the exposure period.  相似文献   

Metal absorption systems in spectra of pairs of QSOs: how absorbers cluster around QSOs and other absorbers     

David Tytler  Mark Gleed  Carl Melis  Angela Chapman  David Kirkman  Dan Lubin  Pascal Paschos  Tridivesh Jena  Arlin P. S. Crotts 《Monthly notices of the Royal Astronomical Society》2009,392(4):1539-1572

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Conflating Privilege and Vulnerability: A Reflexive Analysis of Emotions and Positionality in Postgraduate Fieldwork   总被引：1，自引：0，他引：1  

Martina Angela Caretta  Johanna Carolina Jokinen 《The Professional geographer》2017,69(2):275-283

Grounded in a self-reflexive, intersectional analysis of positionality, we examine emotions in fieldwork through the autobiographical accounts that we gathered during our postgraduate ethnographic research in the Global South. We show how we, two female early-career geographers, emotionally coped with instances that put us in a vulnerable position due to loneliness, commitment to the field, insistent questioning, violence, and violent threats. We argue that a culture of silence surrounding fieldwork difficulties and their emotional consequences tend to permeate our discipline. We contend that geography departments ought to provide mentorship that takes into account doctoral candidates' different positionalities, conflated vulnerability and privilege, and embodied intersectional axes. This renewed awareness will help not only to reveal possible risks and challenges connected with fieldwork but also ultimately to enrich the overall academic discussions within our discipline.  相似文献   

Late Pleistocene outburst floods from Issyk Kul,Kyrgyzstan?          下载免费PDF全文

Swenja Rosenwinkel  Angela Landgraf  Wolfgang Schwanghart  Friedrich Volkmer  Atyrgul Dzhumabaeva  Silke Merchel  Georg Rugel  Frank Preusser  Oliver Korup 《地球表面变化过程与地形》2017,42(10):1535-1548

Elevated shorelines and lake sediments surrounding Issyk Kul, the world's second largest mountain lake, record fluctuating lake levels during Quaternary times. Together with bathymetric and geochemical data, these markers document alternating phases of lake closure and external drainage. The uppermost level of lake sediments requires a former damming of the lake's western outlet through the Boam gorge. We test previous hypothesised ice or landslide dam failures by exploring possible links between late Quaternary lake levels and outbursts. We review and recompile the chronology of reported changes in lake site, and offer new ages of abandoned shorelines using ¹⁴C in bivalve and gastropod shells, and plant detritus, as well as sand lenses in delta and river sediments using Infrared Stimulated Luminescence. Our dates are consistent with elevated lake levels between ~45 ka and 22 ka. Cosmogenic ¹⁰Be and ²⁶Al exposure ages of fan terraces containing erratic boulders (>3 m) downstream of the gorge constrain the timing of floods to 20.5–18.5 ka, postdating a highstand of Issyk Kul. A flow‐competence analysis gives a peak discharge of >10⁴ m³ s^–1 for entraining and transporting these boulders. Palaeoflood modelling, however, shows that naturally dammed lakes unconnected to Issyk Kul could have produced such high discharges upon sudden emptying. Hence, although our data are consistent with hypotheses of catastrophic outburst floods, average lake‐level changes of up to 90 mm yr^–1 in the past 150 years were highly variable without any outbursts, so that linking lake‐level drops to catastrophic dam breaks remains ambiguous using sedimentary archives alone. This constraint may readily apply to other Quaternary lakes of that size elsewhere. Nonetheless, our reconstructed Pleistocene floods are among the largest reported worldwide, and motivate further research into the palaeoflood hydrology of Central Asia. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

The impact of climate change on extreme precipitation in Sicily,Italy          下载免费PDF全文

Angelo Forestieri  Elisa Arnone  Stephen Blenkinsop  Angela Candela  Hayley Fowler  Leonardo V. Noto 《水文研究》2018,32(3):332-348

Increasing precipitation extremes are one of the possible consequences of a warmer climate. These may exceed the capacity of urban drainage systems, and thus impact the urban environment. Because short‐duration precipitation events are primarily responsible for flooding in urban systems, it is important to assess the response of extreme precipitation at hourly (or sub‐hourly) scales to a warming climate. This study aims to evaluate the projected changes in extreme rainfall events across the region of Sicily (Italy) and, for two urban areas, to assess possible changes in Depth‐Duration‐Frequency (DDF) curves. We used Regional Climate Model outputs from Coordinated Regional Climate Downscaling Experiment for Europe area ensemble simulations at a ~12 km spatial resolution, for the current period and 2 future horizons under the Representative Concentration Pathways 8.5 scenario. Extreme events at the daily scale were first investigated by comparing the quantiles estimated from rain gauge observations and Regional Climate Model outputs. Second, we implemented a temporal downscaling approach to estimate rainfall for sub‐daily durations from the modelled daily precipitation, and, lastly, we analysed future projections at daily and sub‐daily scales. A frequency distribution was fitted to annual maxima time series for the sub‐daily durations to derive the DDF curves for 2 future time horizons and the 2 urban areas. The overall results showed a raising of the growth curves for the future horizons, indicating an increase in the intensity of extreme precipitation, especially for the shortest durations. The DDF curves highlight a general increase of extreme quantiles for the 2 urban areas, thus underlining the risk of failure of the existing urban drainage systems under more severe events.  相似文献