bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controls on the stability and inclinations of hillslopes formed on hard rock
Authors: Selby M. J. 
Published: February 2007

AbstractIn identifying controls on rock slope form a distinction is made between: (1) rock slopes with joints which dip steeply out of a cliff and hence are subject to mass failure of the rock mass above a critical joint; and (2) rock slopes with inclinations which are either in equilibrium with the mass strength of their rocks, or have profiles which will develop towards strength equilibrium as cross joints open. In the first class of slope, stability results not just from the basic frictional resistance of the rock but also from the frictional roughness along the critical joint and from the normal stress acting across that joint. Stability may be reduced by weathering and loss of strength of the joint wall rock. As a result of normal stress variations with depth, induced by overburdens, high cliffs which are not undercut have a concave profile. The second group of slopes includes those with inclinations controlled at the scale of individual joint blocks, buttressed slopes and those on unjointed rock masses. Buttressed and unjointed rock masses develop towards a condition of mass strength equilibrium as cross joints open. Strength equilibrium slopes may be recognized by application of a rock mass strength classification proposed for geomorphic purposes. Eleven propositions are formulated which identify controls on rock slope development and some consequences of these controls.
‘frost and salt’ weathering: Further experimental results
Authors: McGreevy J. P. 
Published: February 2007

AbstractA laboratory experiment has been conducted to examine the effects of ‘frost and salt’ weathering (i.e. physical breakdown by the freezing of salt solutions) on a limestone. Results show that the presence of certain salts in solution can inhibit frost damage. These findings are in direct conflict with those presented by Goudie (1974) and, more recently, Williams and Robinson (1981).Comparison of the experimental methods used in each of these three studies suggests that opposing results can be explained in terms of the different experimental procedures which were employed. If salt supply is frequent and plentiful then it seems likely that rock breakdown will be enhanced‐this is the case represented by the experiment of Williams and Robinson. Conversely if the salt supply is limited and the amounts of salt remain more or less constant then rock breakdown will be inhibited‐the case of the present experimental study. Caution is therefore advocated when attempting to extrapolate laboratory‐derived results to infer on the behaviour of rocks under natural conditions.Several environmental situations in which ‘frost and salt’ weathering may be a possibility are dsiscussed, but it is concluded that further field data, especially concerning temperature regimes and salt availability at and below rock surfaces in cold regions, would be necessary before more definite statements could be made about the efficacy of this process.
A model of two‐phase bedload transport in an oregon coast range stream
Authors: Jackson W. L. , Beschta R. L. 
Published: February 2007

AbstractA descriptive model for bed material routing in small sand and gravel bedded channels with sequences of pools and armoured riffles was developed. Aspects of the model are demonstrated at Flynn Creek, a 202‐ha, third‐order drainage in the Oregon Coast Range. Assuming that channel geometry, sediment transport competence, and the availability of sediments for transport are all non‐uniform in the downstream direction, the model described bedload transport as occurring in two phases. Phase I involves the transport of fine, predominantly sand‐sized bed materials over stable gravel‐armoured riffles. Phase II occurs at higher flows that can entrain riffle armour and transport riffle sediments, in addition to Phase I sediments. Phase I bedload transport was sampled during three moderate flow events. A power function related Phase I bedload transport to water discharge. The relationship was consistent between storms and between two successive years. Phase II bedload transport, sampled during a 1.8‐yr return period streamflow event in February, 1979, proved non‐uniform in a downstream direction and unsteady over time at a given stream discharge. Transport rates closely correlated with the rapid scour and redeposition of the riffle at the bedload sampling cross‐section; transport peaks corresponded to scour and transport decreased greatly during deposition. The transport of large (> 12.5 mm diam.) bed material increased up to 12‐fold during riffle scour.
Medium‐term effects of two landsliding episodes on channel storage of sediment
Authors: Pearce Andrew J. , Watson Alex 
Published: February 2007

AbstractTwo landsliding episodes between late 1973 and early 1975 delivered about 60000 m3 of sediment to six small deeply incised streams draining a 2·7 km2 area. About 4700 m3 of logs in the landslide debris formed major log jams in five streams, which impounded large volumes of landslide‐derived sediment. Five years after the landsliding, 42 per cent (25000 m3) of sediment was still in storage behind 35 log jams ranging from 1·4–8·2 m high. The landsliding episodes have produced multi‐stepped stream profiles, aggradation of channel reaches up to 150 m long to mean depths between 1·2 and 4·1 m, reductions in gradient, fining of bed material size, and related changes in bedforms and channel width:depth ratios that seem likely to persist for at least several decades. Sediment presently stored behind log jams is equivalent to between 50 and 220 years normal supply of sediment from hillslopes to stream channels. Long‐delayed, large magnitude impacts on higher‐order channels may occur if sudden failure of log jams is induced by a large storm at some future date.
On the estimation of spatial autocorrelation in geomorphology
Authors: Cox Nicholas J. 
Published: February 2007

AbstractAttention is drawn to the existence of different estimators of autocorrelation in one‐dimensional series. It is shown that variation between estimates for series which appear only mildly nonstationary may be of the same order as sampling variation expected under stationarity. Hence it is important that investigators choose estimators carefully and state their choices explicitly.
Pore water pressure and stability conditions on a motorway embankment
Authors: Anderson Malcolm G. , Kneale Pauline E. 
Published: February 2007

AbstractPrior to the occurrence of a shallow surface slip on a clay embankment a tensiometer system was installed to continuously monitor pore water conditions. It is shown that high pore water pressures can develop in clay embankments after periods of continuous low intensity precipitation. Using stability analyses it is demonstrated that for this first time slide, the clay fill material had a shear strength above residual values and a small but finite cohesion.
The permanence of stream networks in Britain
Authors: Ovenden J. C. , Gregory K. J. 
Published: February 2007

AbstractStream networks used in studies of basin morphometry, network topology, flood hydrology, and sediment production should be defined as precisely as possible. Previous work has drawn attention to the way in which stream network definition varies on maps of different scales, on maps employing different conventions devised in relation to the dynamic network, and according to whether maps, remote sensing or field survey sources are used. Networks also vary in extent according to the date of survey and after considering the instructions to surveyors it is shown that such changes, over periods of 100 years reflect changes in network extent. For three areas of Britain, network change can be identified by comparison of maps of different dates, by comparison of these changes with the results of field survey, and by reference to dateable features such as inclosure boundaries. Changes of drainage networks since the nineteenth century are shown to be significant in extent and they have often occurred as a result of the replacement of flushes by clearly defined stream channels. This transformation has often occurred as a result of new or modified systems of stormwater drainage from roads, tracks or farms, and the planning of the future disposal of road drainage should be considered carefully in relation to such stream network changes. The changes of drainage networks identified from maps of different dates and editions can provide a useful data base for studies of network topology and may also be significant in relation to palaeohydrological investigations.
Magnitude and distribution of rates of river bank erosion
Authors: Hooke J. M. 
Published: February 2007

AbstractMeasurements of bank erosion on rivers in Devon over a 2½ year period produced mean rates ranging from 0.08 to 1.18 metres per year and a maximum rate of 2.58 metres per year. These values are compared with rates derived from maps for various time periods between 1840 and 1975. The map rates are generally lower than the field rates and the question of whether this difference is due to the method of measurement, the magnitude‐frequency of events, a change in discharge conditions or the inherent variation in channel activity is discussed. Published data on bank erosion rates are reviewed and the Devon rates are found to coincide with the worldwide distribution. An analysis of factors likely to influence the spatial distribution of erosion rates reveals a square‐root relationship to catchment area and the importance of bank material. Implications of the measured rates for development of flood plains are examined.
Hydrochemical aspects of the negro river, patagonia, argentina
Authors: Depetris Pedro J. 
Published: February 2007

AbstractWater samples collected in the Negro River drainage basin (Patagonia, Argentina) during two different field trips—the first in May 1972 and the second in January 1973—were analysed for the major dissolved inorganic constituents. Q‐mode factor analyses demonstrate that two factors account for over 98 per cent of the variance in both sample suites. They represent: a) the direct influence of solution of evaporites and associated carbonate rocks in an arid environment‐type; b) the influence of the weathering products of metamorphic, igneous rocks, and varied non‐calcareous sediments. R‐mode factor analyses of the two sets of data suggest that although the main mechanisms controlling water chemistry were essentially the same, the principal sources of dissolved solids differed significantly in each separate occasion. Further, the major mechanisms controlling its water chemistry are within a wide spectrum of the so‐called ‘rock dominance’.
Field studies of sediment transport by overland flow
Authors: Morgan R. P. C. 
Published: February 2007

AbstractField studies on sandy soils of the Cottenham Series in mid‐Bedfordshire show that the mean annual rate of sediment transport by overland flow on an 11° mid‐slope is 98 g cm1. The feasibility of using sediment transport equations to predict erosion by overland flow on a storm basis is examined by comparing the observed values of sediment yield with values predicted by four sediment transport equations and a regression equation which relates soil loss to runoff energy and rainfall energy. An expression combining Engelund's sediment transport capacity equation and the Manning equation for flow velocity, as modified by Savat for disturbed flow, best reflects field conditions. Although there is a significant correlation (r = 0.69; n 30) between the observed and predicted values using this expression, the coefficient of determination is too low for predictive purposes. Reasons for this are presented.
Forms of bluffs degraded for different lengths of time in emmet county, Michigan, U.S.A.
Authors: Nash David 
Published: February 2007

AbstractDistinct differences in morphology are found among bluffs cut and abandoned by Glacial Lake Algonquin and by the Nipissing Great Lakes in Emmet County, Michigan and modern, active bluffs presently being eroded by Lake Michigan in Mason and Manistee Counties, Michigan. The Algonquin, Nipissing, and modern bluffs are all composed of a sandy, morainic material. Because the composition and mode of formation of the three sets of bluffs are similar, it is assumed that the abandoned bluffs had the same initial configuration as the modern bluff. The morphologic differences are likely a function of the different periods of time each bluff has degraded. With time, the angle of the bluff midsection decreased, the extent of the convex crest and the concave base increased, and the angle of the crest increased. This course of hillslope degradation is believed similar to that occurring elsewhere on heavily vegetated hillslopes underlain by cohesionless material and situated in temperate, humid climates. The morphologic changes may be understood in terms of an analytical model which assumes that the rate of change in elevation at a point on a hillslope profile is proportional to the profile curvature at that point.
Channel morphology and sediment movement in a tidal river, pitt river, British Columbia
Authors: Ashley Gail M. 
Published: February 2007

AbstractThe Pitt River is a meandering river channel linking the Fraser River estuary and Pitt Lake. The lake acts as a temporary reservoir for tidally diverted Fraser River flow. Stage level can fluctuate 2 m in Pitt River and as much as 1.2 m in Pitt Lake on a tidal cycle. Stage data from three locations in the system, used in conjunction with velocity measurements (profiles and tethered meter), revealed large tidal and seasonal variations in discharge. Calculations indicate that during the flood, basal shear stress peaks earlier in the cycle and reaches higher values than during the ebb. Thus, sediment moves farther forward on a flood flow than it moves back on the succeeding ebb. An upstream movement of sediment in Pitt River from the Fraser River is indicated by: (1) the identical mineralogy of the two rivers, (2) a decrease in median grain size from the Fraser to Pitt Lake, and (3) a predominance of flood‐oriented bedforms in the river channel. A delta, 12 km2 area, has accumulated at the lower (draining) end of the lake.Studies of the river channel using hydrographic charts revealed regular meanders (λM = 6100 m) and evenly spaced riffles and pools which appear to be scaled to the strongest flow, winter flood current (2400 m3/s). The winter flood is thus considered to be the effective discharge. Meander point bars are accreting on the ‘upstream’ side indicating deposition by the flood‐oriented flow. The three dimensional geometry of the large‐scale bedforms which cover the sandy thalweg of both river and delta channel was determined by echo sounding and side‐scan sonar. Three distinct sizes (height/spacing = 0.8 m/10–15 m; 1.5 m/25–30m; 3m/50–60 m) of large‐scale bedforms (sand waves) were found; their linear relationship of height vs. spacing on a log‐log plot suggests a common genesis. Their occurrence by size does not appear to be related to depth of flow but rather to their position in the channel with respect to large scale features which alter flow.
An efficient approximation method for American exotic options
Authors: Chang Geunhyuk , Kang Jangkoo , Kim Hwa‐Sung , Kim In Joon 
Published: February 2007

AbstractThe authors suggest a modified quadratic approximation scheme, and apply this scheme to American barrier (knock‐out) and floating‐strike lookback options. This modified scheme introduces an additional parameter into the quadratic approximation method, originally suggested by G. Barone‐Adesi and R. Whaley (1987), to reduce pricing errors. When the barrier is close to the underlying asset's current price, the approximation formula is more accurate than lattice methods because the optimal exercise boundary is independent of the underlying asset's current price. That is, the proposed method overcomes the “near‐barrier” problem that occurs in lattice methods. In addition, the pricing error decreases when the underlying asset's volatility is high. This approximation scheme is more efficient than B. Gao, J. Huang, and M. Subrahmanyam's (2000) method. As a second application of the modified approximation scheme, the authors provide an approximation formula for American floating‐strike lookback options which is the first approximation formula ever suggested in the literature. Compared to S. Babbs' (2000) binomial approach, our approximation method is more efficient after controlling for pricing errors, and is more accurate after controlling for computing time. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:29–59, 2007
Back to the future: Futures margins in a future credit default swap index futures market
Authors: Byström Hans N. E. 
Published: February 2007

AbstractThe introduction of exchange‐traded credit default swap (CDS) index futures is eminent and this development in the credit market is the subject of this article. A theoretically appealing and practically implementable approach to computing accurate futures margins based on extreme value theory is suggested. The approach is then exemplified with a study of the increasingly popular iTraxx Europe CDS index market. Although this market is not organized through an exchange and is not a futures market, the empirical results together with an arbitrage argument nonetheless suggest margin levels in a future exchange‐traded CDS index futures market computed using extreme value theory to be superior to those computed using the traditional normal distribution or the actual historical distribution. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:85–104, 2007
Extreme volatility, speculative efficiency, and the hedging effectiveness of the oil futures markets
Authors: Switzer Lorne N. , El‐Khoury Mario 
Published: February 2007

AbstractThis study investigates the efficiency of the New York Mercantile Exchange (NYMEX) Division light sweet crude oil futures contract market during recent periods of extreme conditional volatility. Crude oil futures contract prices are found to be cointegrated with spot prices and unbiased predictors of future spot prices, including the period prior to the onset of the Iraqi war and until the formation of the new Iraqi government in April 2005. Both futures and spot prices exhibit asymmetric volatility characteristics. Hedging performance is improved when asymmetries are accounted for. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:61–84, 2007
Characterization of t(6;11)(p21;q12) in a renal‐cell carcinoma of an adult patient
Authors: Pecciarini Lorenza , Cangi M. Giulia , Lo Cunsolo Crocifissa , Macri' Ettore , Dal Cin Elena , Martignoni Guido , Doglioni Claudio 
Published: February 2007

AbstractRenal‐cell carcinoma (RCC) constitutes a heterogeneous group of tumors with specific chromosome aberrations. Recently, a new small group of RCC, occurring in children and young adults, has been described as characterized by t(6;11)(p21;q12). It has been shown that this translocation results in the fusion of the 5′ portion of the ALPHA gene (11q12) with the transcription factor gene TFEB (6p21). Herewith, we report the first complete cytogenetic and molecular characterization of a t(6;11)‐positive RCC of an adult patient, a 54‐year‐old woman. The tumor was histologically defined as RCC with peculiar features and it was negative for epithelial markers and positive for melanocytic markers. Chromosome QFQ banding analysis of short‐term cultured cells from the RCC showed t(6;11)(p21;q12) as the sole cytogenetic abnormality. The translocation was confirmed by FISH analysis. RT‐PCR analysis, performed on total RNA isolated from both neoplastic and normal tissue samples, revealed an ALPHA–TFEB chimeric transcript in the tumor sample; sequencing of the RT‐PCR product defined a novel TFEB gene breakpoint cluster region, broader than the one reported thus far. Western blot analysis showed a band at the expected size of wild‐type TFEB in the neoplastic tissue compared to the normal sample, supporting that the fusion gene does not encode for a chimeric protein but it causes an upregulation of the wild‐type TFEB. Our data contribute to define better this rare RCC type, which is typical not only of childhood but can also be found in adulthood. © 2007 Wiley‐Liss, Inc.
Cytogenetic patterns in ETV6/RUNX1‐positive pediatric B‐cell precursor acute lymphoblastic leukemia: A Nordic series of 245 cases and review of the literature
Authors: Forestier Erik , Andersen Mette K. , Autio Kirsi , Blennow Elisabeth , Borgström Georg , Golovleva Irina , Heim Sverre , Heinonen Kristina , Hovland Randi , Johannsson Johann H. , Kerndrup Gitte , Nordgren Ann , Rosenquist Richard , Swolin Birgitta , Johansson Bertil ,   on behalf of the Nordic Society of Pediatric Hematology and Oncology (NOPHO),   the Swedish Cytogenetic Leukemia Study Group (SCLSG),   and the NOPHO Leukemia Cytogenetic Study Group (NLCSG)
Published: February 2007

AbstractBetween 1992 and 2004, 1,140 children (1 to <15 years) were diagnosed with B‐cell precursor acute lymphoblastic leukemia (ALL) in the Nordic countries. Of these, 288 (25%) were positive for t(12;21)(p13;q22) [ETV6/RUNX1]. G‐banding analyses were successful in 245 (85%); 43 (15%) were karyotypic failures. The modal chromosome numbers, incidence, types, and numbers of additional abnormalities, genomic imbalances, and chromosomal breakpoints in the 245 karyotypically informative cases, as well as in 152 previously reported cytogenetically characterized t(12;21)‐positive ALLs in the same age group, were ascertained. The most common modal numbers among the 397 cases were 46 (67%), 47 (16%), 48 (6%), and 45 (5%). High‐hyperdiploidy, triploidy, and tetraploidy were each found in ∼1%; none had less than 40 chromosomes. Secondary chromosomal abnormalities were identified by chromosome banding in 248 (62%) of the 397 ALLs. Of these, 172 (69%) displayed only unbalanced changes, 14 (6%) only balanced aberrations, and 26 (10%) harbored both unbalanced and balanced abnormalities; 36 (15%) were uninformative because of incomplete karyotypes. The numbers of secondary changes varied between 1 and 19, with a median of 2 additional aberrations per cytogenetically abnormal case. The most frequent genomic imbalances were deletions of 6q21‐27 (18%), 8p11‐23 (6%), 9p13‐24 (7%), 11q23‐25 (6%), 12p11‐13 (27%), 13q14‐34 (7%), loss of the X chromosome (8%), and gains of 10 (9%), 16 (6%), and 21 (29%); no frequent partial gains were noted. The chromosome bands most often involved in structural rearrangements were 3p21 (2%), 5q13 (2%), 6q12 (2%), 6q14 (2%), 6q16 (2%), 6q21 (10%), 6q23 (6%), 6q25 (3%), 9p13 (2%), 11q13 (2%), 11q23 (2%), 12p11 (6%), 12p12 (7%), 12p13 (25%), 21q10 (6%), and 21q22 (6%). Considering that the t(12;21) is known to arise in utero and that the postnatal latency period is protracted, additional mutations are most likely necessary for overt ALL. The frequently rearranged chromosome regions may harbor genes of importance for the transformation and/or progression of an initial preleukemic t(12;21)‐positive clone. © 2007 Wiley‐Liss, Inc.