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V. Stanishev 《Astronomische Nachrichten》2007,328(9):948-952
An empirical method for correcting low‐resolution astronomical spectra for second‐order contamination is presented. The method was developed for correcting spectra obtained with grism#4 of the ALFOSC spectrograph at the Nordic Optical Telescope and the performance is demonstrated on spectra of two nearby bright Type Ia supernovae. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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A. Pastorello S. Taubenberger N. Elias-Rosa P. A. Mazzali G. Pignata E. Cappellaro G. Garavini S. Nobili G. C. Anupama D. D. R. Bayliss S. Benetti F. Bufano N. K. Chakradhari R. Kotak A. Goobar H. Navasardyan F. Patat D. K. Sahu M. Salvo B. P. Schmidt V. Stanishev M. Turatto W. Hillebrandt 《Monthly notices of the Royal Astronomical Society》2007,376(3):1301-1316
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Derk C. Bergquist Jason P. Andras Tim McNelis Sarah Howlett Mark J. van Horn & Charles R. Fisher 《Marine Ecology》2003,24(1):31-44
Abstract. The slow rate of change in hydrocarbon seep communities on the upper Louisiana slope prevents the use of direct observation in studying successional trends. We used a chronosequence consisting of three presumed stages – juvenile, adult and senescent – to test a previous model which proposed that sulfide availability and vestimentiferan growth and physiological health decline over the lifespan of a vestimentiferan aggregation. We replicated the chronosequence at two sites to simultaneously explore the influence of spatial heterogeneity on the characteristics of these communities. We determined environmental sulfide concentrations and vestimentiferan growth and condition in at least two vestimentiferan aggregations representative of each stage at each of these two sites. Hydrogen sulfide concentrations were highly variable both above and below the sediment's surface, and sulfide was present in high concentrations to sediment depths of 70 cm. Vestimentiferan growth and condition varied significantly on multiple spatial scales from sites separated by tens of kilometers, to aggregations separated by tens to hundreds of meters within a site, to individual vestimentiferans separated by tens of centimeters within an aggregation. The striking variability in both environmental sulfide and vestimentiferan growth and condition within individual aggregations suggests a crucial role for microhabitat variability in the persistence of vestimentiferan aggregations at these sites. Few significant successional trends in environmental sulfide or vestimentiferan growth and condition were found over the three stages tested. 相似文献
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The life history of the amphipod Orchestia sp. cf. cavimana (Heller, 1865) was studied throughout the course of a year with monthly samplings and the use of pitfall traps along the shores of Lake Albano in central Italy. The data thus obtained showed two peaks in abundance (the first in June and the second in October) and a minimum capture frequency in February. Egg-bearing females were recorded in spring and late summer, whilst recruitment occurred from spring to autumn, with maximum in June and October. The data collected also indicated the presence of a positive correlation between the abundance of talitrids and both temperature and sediment moisture. Morphological analysis enabled the identification of four different cohorts (with a lifespan of the species of approximately 12–15 months) all four of which remained distinguishable throughout the course of the year. It, moreover, enabled sex determination in individuals of 5 or more millimetres. The subsequent distribution indicated that, when significant, the sex ratio was female biased and that maximum size was greater in males. In particular, maximum sizes were recorded in spring for both males and females and were of 17.5 and 13.0 mm, respectively. Furthermore, the total body length recorded for egg-bearing females was positively correlated with the number of eggs in their brood pouch. 相似文献
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Rapid societal change as a proxy for regional environmental forcing: Evidence and explanations for Pacific island societies in the 14–15th centuries 
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下载免费PDF全文 Given the unquestioned impacts of recent/future environmental changes on human societies, it is reasonable to posit that past societal responses could be used as proxies of contemporaneous environmental forcing and might help identify the drivers of these, particularly where independent evidence of the effects of these events is inadequate. Such areas include Pacific oceanic islands for most of which there is evidence of a societal perturbation in the 14th and 15th centuries that saw the outbreak of region‐wide conflict, abandonment of coastal settlements and the abrupt end of long‐distance cross‐ocean voyaging networks. The contemporaneity of these effects across a vast region requires a driver that is external to particular island groups with the only possibility that of oceanic origin, most likely large waves (tsunamis or storm surges) or rapid sea‐level change. The explanation is less important than the principle that societal changes can be used as proxies for environmental activity. 相似文献
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描述了河北省赤城县寺梁山土城子(后城)组一例极可能的兽脚类恐龙蹲伏迹及相关的足迹,该蹲伏迹也是该组地层目前发现的最大的兽脚类足迹。虽然缺乏前足迹和尾迹,但因保存了左跖骨印、关联的坐骨及可能的耻骨胼胝印被定为蹲伏迹。该蹲伏迹是世界上第三例非对称的兽脚类恐龙蹲伏迹。 相似文献