Detecting filaments in the ultra-high energy cosmic ray distribution     

Diego Harari  Silvia Mollerach  Esteban Roulet   《Astroparticle Physics》2006,25(6):412-418

We propose and test new statistical tools to study the distribution of cosmic rays based on the use of the minimal spanning tree. The method described is particularly sensitive to filamentary structures, as those expected to arise from strong sources of charged cosmic rays which get deflected by intervening magnetic fields. We also test the method with data available from the AGASA and SUGAR surface detector arrays.  相似文献   

A palaeomagnetic study of the Builth Wells-Llandrindod Wells Ordovician Inlier, Wales: palaeogeographic and structural implications     

Allan Trench  Trond H. Torsvik  Mark A. Smethurst  Nigel H. Woodcock  Richard Metcalfe 《Geophysical Journal International》1991,105(2):477-489

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Human geo-ecological interactions in Kuh Daman,a South Asian mountain valley     

Nigel J.R. Allan 《Applied geography (Sevenoaks, England)》1985,5(1):13-27

A meso-scale methodology for obtaining and analysing primary data from an isolated mountain environment is described. By combining village cropping data with irrigation water supply and tribal affiliation, the systemic relationships between these features are delineated for 410 villages in a Hindukush mountain valley. The emergent highly variable cropping systems indicate congruity with tribal affiliation and also with agronomy. This inclusion of cultural factors in regional mountain research appears to be a necessary precondition for microscale geo-ecological research.  相似文献   

The Sun,An Introduction,by M. Stix,Astronomy and Astrophysics Library,Springer Berlin,Heidelberg, New York,Barcelona, Hong Kong,London, Milan,Paris, Tokyo, 2nd ed. 2002, XVI+490 pp., EUR 79,95, hardback (ISBN: 3-540-42886-0)     

Nigel Weiss 《地球物理与天体物理流体动力学》2013,107(5):421-423

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Overbank block-and-ash flow deposits and the impact of valley-derived, unconfined flows on populated areas at Merapi volcano, Java, Indonesia     

Ralf Gertisser  Nigel J. Cassidy  Sylvain J. Charbonnier  Luigia Nuzzo  Katie Preece 《Natural Hazards》2012,60(2):623-648

Merapi, an andesitic volcanic complex in Central Java, is one of the most frequently erupting volcanoes in Indonesia and poses a permanent threat to the surrounding population of over 1 million people. With frequently recurring volcanic activity, the sixty or so reported eruptions since the mid-1500s have caused ~7,000 fatalities and destroyed numerous villages in the region. In June 2006, an eruption affected the densely populated area on the volcano’s southern and south-eastern flanks for the first time in almost a century. The resultant block-and-ash flows (BAFs) travelled down an incised river valley (Kali Gendol) to a distance of 7 km from the source, breaking out of the main channel at four main locations. Unconfined (overbank) BAFs were generated, which covered the interfluve regions on either side of the main valley and buried buildings and other infrastructure features in the village of Kaliadem, situated on the western bank of the Gendol valley ~5 km from the summit of Merapi. Using traditional volcanological field-based methods and non-invasive, high-resolution ground-penetrating radar techniques, the morphology and internal architecture of these overbank deposits were studied in detail in order to evaluate the destructive impact of these flows in a local context. The results show that complex, local-scale variations in flow dynamics and deposit architectures are apparent and that BAFs are capable of transporting significant numbers of large blocks (>1–2 m) out of the valley confines. We propose a conceptual model for the escape of these channelised BAFs onto the interfluvial terrace at Kaliadem and show, through a stratigraphic analysis of the pyroclastic successions underlying the village and adjacent areas on the volcano’s southern flank, that the area has been affected repeatedly by overbank BAFs and explosive eruptions over the past few 100 years (and more).  相似文献   

Kolmogorov–Smirnov test as a tool to study the distribution of ultra-high energy cosmic ray sources     

D. Harari  S. Mollerach  E. Roulet 《Monthly notices of the Royal Astronomical Society》2009,394(2):916-922

We analyse in detail the two-dimensional Kolmogorov–Smirnov test as a tool to learn about the distribution of the sources of the ultra-high energy cosmic rays. We confront, in particular, models based on active galactic nuclei observed in X-rays, galaxies observed in H  i and isotropic distributions, discussing how this method can be used not only to reject isotropy but also to support or reject specific source models, extending results obtained recently in the literature.  相似文献   

A method for incorporating climate variability in climate change impact assessments: Sensitivity of river flows in the Eden catchment to precipitation scenarios   总被引：1，自引：1，他引：0  

Ralph Ledbetter  Christel Prudhomme  Nigel Arnell 《Climatic change》2012,113(3-4):803-823

Interest in the impacts of climate change is ever increasing. This is particularly true of the water sector where understanding potential changes in the occurrence of both floods and droughts is important for strategic planning. Climate variability has been shown to have a significant impact on UK climate and accounting for this in future climate change projections is essential to fully anticipate potential future impacts. In this paper a new resampling methodology is developed which includes the variability of both baseline and future precipitation. The resampling methodology is applied to 13 CMIP3 climate models for the 2080s, resulting in an ensemble of monthly precipitation change factors. The change factors are applied to the Eden catchment in eastern Scotland with analysis undertaken for the sensitivity of future river flows to the changes in precipitation. Climate variability is shown to influence the magnitude and direction of change of both precipitation and in turn river flow, which are not apparent without the use of the resampling methodology. The transformation of precipitation changes to river flow changes display a degree of non-linearity due to the catchment’s role in buffering the response. The resampling methodology developed in this paper provides a new technique for creating climate change scenarios which incorporate the important issue of climate variability.  相似文献   

Editorial     

Nigel John Cook  Editor-in-Chief  Ore Geology Reviews 《Ore Geology Reviews》2010,38(4):1

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Textural variation in the pyrite-rich ore deposits of the Røros district, Trondheim Region, Norway: implications for pyrite deformation mechanisms     

Craig D. Barrie  Nigel J. Cook  Alan P. Boyle 《Mineralium Deposita》2010,45(1):51-68

The Røros district is a pyrite-rich polymetallic sulfide orefield in the southeastern part of the Trondheim region, Central Norwegian Caledonides. All of the ore deposits at Røros are hosted within a Cambrian to Silurian succession that was deformed and metamorphosed at lower greenschist to lower amphibolite facies conditions during the Caledonian orogeny. Samples from five individual deposits across the orefield have been analyzed using a combination of reflected light petrographic observation, orientation contrast imaging, and electron backscatter diffraction. Results indicate that, whereas samples from each ore deposit have a variety of different textures, all of them preserve plastic deformation in pyrite grains that occurred at peak metamorphic conditions characterized by the development of internal lattice misorientation within pyrite grains and low-angle (～2°) dislocation walls. These observations indicate that the principal deformation mechanisms at peak metamorphic conditions were dislocation glide and creep. The preservation of brittle fracturing represents later overprinting events.  相似文献   

Subsurface lithofacies analysis of the Fluvial Early Permian Warchha Sandstone, Potwar Basin, Pakistan     

Shahid Ghazi  Nigel P. Mountney 《Journal of the Geological Society of India》2010,76(5):505-517

The Early Permian Warchha Sandstone is well preserved in subsurface in the Potwar Basin and the Punjab Plain of Pakistan. However, this succession is only exposed in the Salt Range, and within this region, only a modest number of the many outcrops are of sufficient quality to enable the preparation of lateral and vertical log profiles. From the subsurface, data from five wells drilled in the Salt Range and Potwar Basin have been analysed. Although they are of restricted coverage, these subsurface data — which take the form of gamma ray logs and well cuttings — provide a valuable addition to the outcrop dataset of the Warchha Sandstone as they provide useful information about vertical textural changes, type and thickness of bedding and the nature of sandbody contacts with underlying strata. Overall, the Warchha Sandstone succession is composed of repeated fining-upwards cycles indicative of a meandering fluvial succession. Sub-components of each cycle are themselves classified into six subsurface sedimentary facies. Through comparison with outcropping parts of the succession, the origin and significance of these subsurface facies can be related to specific architectural elements within the meandering fluvial system responsible for generating the Warchha Sandstone succession.  相似文献