bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal variations in bedload transport rates: The effect of progressive bed armouring
Authors: Gomez Basil 
Published: February 2007

AbstractThe quantitative bedload transport data that are presently available confirm that the generalized bedload transport rate‐stream power relationship is applicable to natural streams. However, the bedload transport rate is not solely dependent upon hydraulic parameters, but also upon the inter‐relationship between bed material characteristics and flow properties. Segregation of the surficial bed material, as expressed through the development of an armour coat, limits the availability of transportable material. Under such circumstances observed bedload transport rates are less than the predicted values.The effect which the development of an armoured surface has upon the bedload transport rate is described with reference to bedload and bed material sampling in the Borgne d'Arolla, Valais, Switzerland. The data refer to two periods when the resumption of baseflow conditions following flood events which were of a sufficient magnitude to transport all but the coarsest (0·3–0·5 m) particles on the streambed, provided the opportunity for the bed to adjust to a comparatively stable flow regime. Observed and predicted bedload transport rate‐stream power relationships are compared. The theoretical relationship does not adequately describe conditions in some gravel‐bed channels, since it fails to take into account the effect which armouring may have upon the supply of transportable material.
The geomorphological effectiveness of floods—a contribution stimulated by two recent events in mid‐wales
Authors: Newson Malcolm 
Published: February 2007

AbstractThe occurrence of two ‘rare’ floods (August 1973, August 1977) in the Plynlimon experimental catchments has confirmed the susceptibility of small upland catchments to summer flooding and provided clues to complications in the geomorphological interpretation of floods in terms of their magnitude and frequency. Magnitude may be treated both in terms of work and effectiveness; the emphasis here is on effectiveness, as revealed by simple surveys. The first Plynlimon flood was more effective on slopes and the second in channels, despite peak discharges of similar return periods and almost identical rates of work revealed by bedload trapping. Effectiveness/frequency studies are likely to require a much more detailed approach, subdividing both the characteristics of the flood and the spatial elements of the affected catchments; a simple slope/channel subdivision is found to be suitable for accounts of effectiveness found in the literature on British floods this century. Effectiveness studies also require regular surveys throughout the recovery period following major flooding; in upland catchments these surveys should concentrate on identifying threshold phenomena and illustrating the relationship between effectiveness and work assessments of magnitude.
Hydrologic and sediment modelling studies in the environmental impact assessment of a major tropical dam project
Authors: Pickup G. 
Published: February 2007

AbstractA computer‐based study of the impact of the proposed Wabo hydroelectric scheme on the Purari River, Papua New Guinea was carried out. The HEC‐6 model, Scour and Deposition in Rivers and Reservoirs developed by the Hydrologic Engineering Centre was used to simulate the effect of the dam on sediment transport and erosion in the lower Purari. Two runs with the model were carried out. The first one was used to establish baseline conditions and the second modelled dam impact.Before the study was carried out, data had to be collected on channel geometry, sediment input, river bed material size composition and hydraulic conditions in the river. Supplementary models also had to be developed to fill in gaps in runoff records and to describe flow in the river during power generation.Results of the investigation indicate that limited erosion will occur because of bed‐armouring and the river will adjust towards a new equilibrium condition quite rapidly. The sediment output of the river into the Purari delta will change, load in the clay, silt and sand/gravel fractions decreasing by 22, 53 and 78 per cent respectively.
Resistance to flow past deformable boundaries
Authors: Davies T. R. , Sutherland A. J. 
Published: February 2007

AbstractAn hypothesis from which a general principle covering deformation of alluvial boundaries may be developed is proposed, namely—flow of fluid past a deformable boundary will deform the boundary so as to increase the resistance to flow. Upon attainment of a local maximum of resistance to flow the boundary shape will cease to change. Evidence from channel bed forms, meander geometry and armoured beds is presented to support the hypothesis. One implication of the hypothesis is that channels will adjust so that sediment movement is maximized. The authors would like geomorphologists to test this in their work on landscape evolution.
Stream channel stability and forest drainage in the new forest, hampshire
Authors: Tuckfield C. G. 
Published: February 2007

AbstractThe Forestry Commission carry out drainage work in the uninclosed portion of the New Forest which includes cutting artificial drains and deepening and straightening natural channels. This paper, based on observation of operations on 53 channels for periods up to eight years between 1962 and 1975, examines the geomorphic results of such work. Of 24,000 metres of channel inspected, 24 per cent by length showed erosion, 40 per cent deposition and 36 per cent no apparent change since the work was executed. The subsequent pattern of erosion and deposition within the channels is governed largely by channel slope, but also by the nature of the superficial material and the width: depth ratio of the excavated channel. It is suggested that the choice of some preferred width: depth ratio for a given channel slope might reduce erosion. Instances are given where erosion might be described as severe, 0.5 cubic metres of material per metre of channel per year in two cases, but it appears that after a few years channels stabilize and erosion is also arrested by growth of vegetation.
Co‐amplification of 8p12 and 11q13 in breast cancers is not the result of a single genomic event
Authors: Paterson Anna L. , Pole Jessica C. M. , Blood Katherine A. , Garcia Maria J. , Cooke Susanna L. , Teschendorff Andrew E. , Wang Yanzhong , Chin Suet‐Feung , Ylstra Bauke , Caldas Carlos , Edwards Paul A. W. 
Published: February 2007

AbstractEpithelial cancers frequently have multiple amplifications, and particular amplicons tend to occur together. These co‐amplifications have been suggested to result from amplification of pre‐existing junctions between two chromosomes, that is, translocation junctions. We investigated this hypothesis for two amplifications frequent in breast cancer, at 8p12 and 11q13, which had been reported to be associated in Southern blot studies. We confirmed that both genomic amplification and expression of genes was correlated between the frequently‐amplified regions of 8p and 11q, in array CGH and microarray expression data, supporting the importance of co‐amplification. We examined by FISH the physical structure of co‐amplifications that we had identified by array CGH, in five breast cancer cell lines (HCC1500, MDA‐MB‐134, MDA‐MB‐175, SUM44, and ZR‐75‐1), four breast tumors, and a pancreatic cancer cell line (SUIT2). We found a variety of arrangements: amplification of translocation junctions; entirely independent amplification of the two regions on separate chromosomes; and separate amplification of 8p and 11q sequences in distinct sites on the same rearranged chromosome. In this last arrangement, interphase nuclei often showed intermingling of FISH signals from 8p12 and 11q13, giving a false impression that the sequences were interdigitated. We conclude that co‐amplification of the main 8p and 11q amplicons in breast tumors is not usually the result of a preceding translocation event but most likely reflects selection of clones that have amplified both loci. This article contains supplementary material available at http://www.interscience.wiley.com/jpages/1045‐2257/suppmat. © 2007 Wiley‐Liss, Inc.
Calcareous nannofossils from the Late Jurassic‐Early Cretaceous of Northwest Anatolia, Turkey
Authors: Özkan Sevinç 
Published: February 2007

AbstractWithin the framework of an integrated stratigraphy, a detailed biostratigraphic study of Late Jurassic‐Early Cretaceous (Tithonian‐Valanginian) calcareous nannofossils was carried out in north‐west Anatolia, Turkey.Samples were collected from nine sections spanning the Yosunlukbayiri and Sogukçam Limestone formations. The Yosunlukbayiri Formation consists of alternating green to cream coloured marl and micritic limestone that becomes detrital (calciturbidites) in the upper part. The Sogukçam Limestone Formation, which overlies the Yosunlukbayiri Formation, consists of white to pink, porcellaneous micritic limestone. A semi‐quantitative analysis of calcareous nannofossils was performed mainly using light microscopy. This revealed the first and last occurrences of important marker species, together with fluctuations of abundance and species diversity.Nannofossil assemblages are generally dominated by the most abundant and solution resistant taxa, such as Conusphaera spp., Faviconus multicolumnatus, Nannoconus spp. and Watznaueria spp., and occur in rock‐forming quantities. Five zones (Conusphaera mexicana mexicana Zone, Microstaurus chiastius Zone, Nannoconus steinmannii steinmannii Zone, Retecapsa angustiforata Zone, Calcicalathina oblongata Zone) and 37 biohorizons were recognized from the Tithonian to Valanginian and calibrated to the Calpionellid (Altiner and Özkan 1991) and the foraminiferal‐algal zonation schemes (Altiner 1991).
Identification of genes preferentially expressed by microglia and upregulated during cuprizone‐induced inflammation
Authors: Bédard Andréanne , Tremblay Pierrot , Chernomoretz Ariel , Vallières Luc 
Published: February 2007

AbstractMicroglia, monocytes, and peripheral macrophages share a common origin and many characteristics, but what distinguishes them from each other at the level of gene expression remains largely unknown. In this study, we compared the transcriptional profiles of freshly purified microglia, monocytes, and spleen macrophages using Affymetrix Mouse Genome arrays to identify genes predominantly expressed by microglia. Among tens of thousands of genes assayed, 127 potential candidates were found, including nine newly discovered genes encoding plasma membrane and extracellular proteins. In the brain, the latter were selectively expressed by microglia, as revealed by in situ hybridization. Three of them were confirmed to be exclusively (MSR2) or predominantly (GPR12, GPR34) expressed in the brain compared to the other tissues examined. Furthermore, all of these genes were upregulated in activated microglia after treatment with the demyelinating toxin cuprizone, suggesting that they play roles in neuroinflammation. In conclusion, this study reports the identification of new selective markers for microglia, which should prove useful not only to identify and isolate these cells, but also to better understand their distinctive properties. © 2007 Wiley‐Liss, Inc.
A functional MRI study of happy and sad affective states induced by classical music
Authors: Mitterschiffthaler Martina T. , Fu Cynthia H.Y. , Dalton Jeffrey A. , Andrew Christopher M. , Williams Steven C.R. 
Published: February 2007

AbstractThe present study investigated the functional neuroanatomy of transient mood changes in response to Western classical music. In a pilot experiment, 53 healthy volunteers (mean age: 32.0; SD = 9.6) evaluated their emotional responses to 60 classical musical pieces using a visual analogue scale (VAS) ranging from 0 (sad) through 50 (neutral) to 100 (happy). Twenty pieces were found to accurately induce the intended emotional states with good reliability, consisting of 5 happy, 5 sad, and 10 emotionally unevocative, neutral musical pieces. In a subsequent functional magnetic resonance imaging (fMRI) study, the blood oxygenation level dependent (BOLD) signal contrast was measured in response to the mood state induced by each musical stimulus in a separate group of 16 healthy participants (mean age: 29.5; SD = 5.5). Mood state ratings during scanning were made by a VAS, which confirmed the emotional valence of the selected stimuli. Increased BOLD signal contrast during presentation of happy music was found in the ventral and dorsal striatum, anterior cingulate, parahippocampal gyrus, and auditory association areas. With sad music, increased BOLD signal responses were noted in the hippocampus/amygdala and auditory association areas. Presentation of neutral music was associated with increased BOLD signal responses in the insula and auditory association areas. Our findings suggest that an emotion processing network in response to music integrates the ventral and dorsal striatum, areas involved in reward experience and movement; the anterior cingulate, which is important for targeting attention; and medial temporal areas, traditionally found in the appraisal and processing of emotions. Hum Brain Mapp 2007. © 2006 Wiley‐Liss, Inc.
Relationship among neuroimaging indices of cerebral health during normal aging
Authors: Kochunov Peter , Thompson Paul M. , Coyle Thomas R. , Lancaster Jack L. , Kochunov Valeria , Royall Donal , Mangin Jean‐Fransçois , Rivière Denis , Fox Peter T. 
Published: February 2007

AbstractSensitive measures of brain aging show great promise for gauging factors that affect aging and degenerative processes, such as risk genes or therapy. Here we examined age‐related trends for three indices of cerebral health: gyral gray matter (GM) thickness, dilation of sulcal spaces with CSF, and the volume of T2‐hyperintense white matter (HWM) lesions. The study involved 31 healthy adults age 57–82 years old. Measurements of average GM thickness, average sulcal span and HWM volume were performed using high‐resolution 3D T1‐ and T2‐weighted brain MR images. Age‐related trends for the three cerebral health indices were consistent with previously published work though the analysis of their covariance led to a previously unreported relationship. Simultaneous multiple regression found that dilation of cortical sulci were primarily (t = 2.59, P < 0.01) related to the increases in HWM volume and secondarily related (t = −2.51, P < 0.01) to the reductions of the cortical GM thickness. The are‐corrected correlation between reduction in GM thickness and increases in HWM volume, was not significant (P = 0.34). These findings are of interest in designing quantitative measures of brain aging for monitoring individual patients and in large‐scale clinical trials. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
Rapid drainage response to precipitation
Authors: Germann Peter F. 
Published: February 2007

AbstractRapid drainage flow increases at the 2·4 m depth in the Coshocton lysimeters were related to the storms that most likely initiated them. The time lapsed between the onset of the storm and rapid drainage response was less than 2 days in 98 per cent of the 389 cases observed in five lysimeters between 1976 and 1982.A pronounced seasonal variation in the frequency of rapid responses was found, with the first quarter of the year comprising the highest number of events. During winter, when soil moisture is generally high, a storm yielding 6 mm/d was already sufficient to initiate this response while summer storms producing more than 50 mm/d did not always initiate a drainage response. Average drainage yield per event was found to be more closely related to the type and usage of a soil than to seasonal effects.
An isotopic and geochemical study of snowmelt runoff in a small arctic watershed
Authors: Obradovic Milan M. , Sklash Michael G. 
Published: February 2007

Abstract‘Old’ water contributions to snowmelt runoff in a stream can be defined as water which was stored in the catchment prior to the start of the runoff event in question. We used mass balance techniques for natural oxygen‐18 and several chemical parameters (electrical conductivity, Ca and Mg) to estimate the magnitude and timing of ‘old’ water contributions to snowmelt runoff in the Apex River watershed during the 1983 field season. The Apex River catchment is located in the southern part of Baffin Island, Northwest Territories, Canada. The watershed has an area of 60 km2, it is in the zone of continuous permafrost, and the geology is dominantly Precambrian gneiss with sporadic, thin, glacial overburden. The isotopic data indicate that for the snowmelt season of 1983 (third highest peak discharge of 11 years of record), approximately 50 per cent of the peak stream discharge consisted of ‘old’ water. Our data also suggest that about 60 per cent of the entire 1983 hydrograph was ‘old’ water. The chemical parameters give old water contributions which are at least 10 per cent less than the isotopically‐derived estimate, but they are consistent with the isotopic estimate during peak flow.
The identification of conceptual hydrological models for surface water acidification
Authors: Wheater H. S. , Bishop K. H. , Beck M. B. 
Published: February 2007

AbstractAmbiguity in parameter identification represents a potentially serious limitation to the application of models of surface water acidification. Previous work has concentrated on manipulation of two of the three factors affecting model identifiability, namely model structure and estimator properties. A new technique is proposed which uses different modes of response within the data to improve parameter identification. Preliminary results, obtained using the Birkenes model of surface water acidification, appear to show promise. The technique is robust in recovering model parameters from synthetic data, with and without error, and in assimilating problems of structural error.
Unstable flow in layered soils: A review
Authors: Hillel Daniel 
Published: February 2007

AbstractRelease of water from the soil in the process of internal drainage, and its continued downward movement through the vadose zone, constitute the main mechanism of groundwater recharge. Water released from the soil generally contains solutes, and these are conveyed to the groundwater via the same pathways as the drained water. Knowledge of those pathways is essential in any attempt to minimize the likelihood of groundwater pollution. Solutes generally interact with the medium in which they reside or travel, and the spatial and temporal pattern of their movement influences the nature and extent of their interactions.For many years, the assumption had prevailed that flow in the vadose zone is a steady‐state, uniform process. Hence the vadose zone can serve to filter, attenuate, as well as degrade, potential pollutants. Recently, however, the existence of preferred pathways has come to light. Such pathways might connect the soil's upper zone directly to the water‐table, thus bypassing the greater volume of the vadose zone and evading its filtering mechanisms. Groundwater recharge models that ignore the possibility of such spurts of contamination may be highly misleading.Preferred flow path may be cracks, animal burrows, or decayed root channels. Less easily discernible are transient and random paths associated with the phenomenon of ‘unstable flow’, which is most likely to occur in layered soils during infiltration. The wetting front, instead of remaining horizontal and advancing continuously from one layer to the next, may begin (particularly in transition from a fine‐textured to a coarse‐textured layer) to form bulges, called ‘fingers’, which propagate downwards and may become, in effect, vertical pipes. At present we are aware only of the occasional occurrence and potential importance of such phenomena, but as yet have neither the systematic empirical data, nor a proven comprehensive theoretical framework, by which to assess where, when, and according to what pattern, they are likely to occur.
A revised procedure for discharge measurement by means of the salt dilution method
Authors: Hongve Dag 
Published: February 2007

AbstractDischarge measurement by means of injection of a NaCl‐solution and integration of the electrical conductivity as a function of time is a traditional and well‐documented method for use in turbulent streams. The ease of the chemical measurements permits results to be calculated in the field. This work has shown that dry fine‐grained salt may substitute the salt solution. Correction factors for water temperature and background conductivity are derived from experiments. A simple procedure for calculation of the discharge is described.
The mechanism of unsaturated flow through a volcanic ash layer under humid climatic conditions
Authors: Shimada Jun 
Published: February 2007

AbstractIt is very interesting and meaningful to investigate the rainfall‐groundwater recharge process under the humid climatic condition of Japan, where mean annual precipitation is about 1600 mm. The present study has investigated soil water movement in the unsaturated zones of a volcanic ash layer, called the ‘Kanto Loam formation’, using environmental tritium as a tracer. The site selected is a flat ground surface on a terraced upland which has a deep unsaturated zone (about 20 m) with a relatively high water content (about 70 per cent) consisting of nearly uniform Kanto Loam formation.The tritium concentrations in groundwater, soil waters having different matric potentials, precipitation, and the seepage water moving through the formation into a man‐made cave were measured to characterize the rainfall‐groundwater recharge process and the effect of large pore spaces in the formation mentioned by previous studies.Because of the humid climate of Japan, there appears to be a unique soil water flow characteristic which may involve percolation through large pore spaces during heavy rainfall. However, in a fine grained and high water content soil like the Kanto Loam formation, the existence of this flow through large pore spaces does not have a significant effect upon the whole recharge process. The recharge model of displacement flow with dispersion is useful in estimating the tritium concentration profile of soil water. The calculated result shows a recharge rate of 2.5 mm/day. The value obtained reflects the hydrological characteristics of the uplands covered with volcanic ash.