bluuebunny/crossref_metadata_2025 huggingface dataset:
Rainwash experiments on the erodibility of loose sediments
Authors: Poesen J.
Published: February 2007

Laboratory experiments using simulated rainfall, splash boards and trays were conducted in order to obtain information on the erodibility of loose sediments as a time‐dependent phenomenon. In all, ten different sediments ranging from silt (D50= 24μm) to coarse sand (D50= 593 μm) were studied. The effect of three different initial states of the sediments, namely the air dry state T1, the field capacity state T2, and the desiccated state T3, on the erodibility was also assessed.

Variations in detachability during a rain erosion experiment can be explained by change in water content (including liquefaction and the development of a water layer on the surface), cohesion, and granulometric composition of the top layer. The coarsest sandy sediments almost always yielded the highest detachability when starting from an initial field capacity state, T2. For the finer sediments, the highest detachability was found for the homogeneous and not yet compacted initial air dry state, T1. The effect of the initial desiccated state T3 on the detachability of the finer sediments was also a function of the rainfall duration.

The relationship between detachability and median grain size of the sediments was very similar to the relation between grain size and the susceptibility to runoff and wind erosion established by other investigators. The highest detachability was found for a fine very well sorted sand with a median grain size of 96 μm.
The assessment of chemical weathering rates within an upland catchment in north‐east Scotland
Authors: Reid J. M. , Macleod D. A. , Cresser M. S.
Published: February 2007

A study has been made of weathering in Glendye, an upland catchement of heather moorland underlain mainly by granite with some gneiss in north‐east Scotland. The concentrations of a range of elements and ions in precipitation and river water were measured over a twelve‐month period. The total input and output of each element or ion was calculated. The resulting balances show net outputs of all species except hydrogen ion. Large net outputs of silicon (38.5 kg ha−1 a−1) and bicarbonate (48 kg ha−1 a−1) indicate considerable chemical weathering. A large net output of chloride (32 kg ha−1 a−1) indicates the importance of dry deposition of oceanic aerosols. When this is allowed for the rate of output of elements due to weathering is.

Si>Ca>Na>Mg>K>Fe>Al.

These results were compared with the abundance of elements in bedrock and differential weathering ratios calculated. These are compared with data from the Hubbard Brook study in New Hampshire. In both cases calcium is by far the most mobile element. The relative importance of the atmosphere and of chemical weathering as sources of each element was calculated, and the results compared with those of a study at Wet Sleddale in the Lake District. Similar patterns emerge in both cases.
Sediment yield studies of headwater catchments in Sussex, S.E. England
Authors: Collins M. B.
Published: February 2007

The transport of sediment from six small (0.2 to 17.6 km2) headwater catchments is described. The catchments under investigation were located in relation to predominant lithological deposits within the Cretaceous rock succession; two of the areas were underlain by (Weald) clay, two by sandstone (Ashdown Sand and Tunbridge Wells Sand) and two by chalk. The climate of the region under investigation is temperate, with an average annual precipitation (850 mm) in excess of potential evapotranspiration (450 mm).

The transport of suspended material from within the catchments was examined by collecting samples of the water‐sediment mixture draining the areas, using hand held depth‐integrating and permanently installed stage sampling systems. The results of the regularly maintained sampling programme, over a two‐year period, are described. Attempts were made to both measure and compute bed load transport.

Suspended sediment concentrations are compared between catchments and related to hydrological characteristics. The nature of the material in transit is examined.

Sediment rating curves are derived for each of the headwater catchments, defining the relationship in the form y = Axb (where y = suspended sediment concentration (mg/1) and x = water discharge (m3/s)). Annual rating curves are used to derive annual suspended sediment loads by combination with water discharge data, using a log‐incremental computerized approach. Multiple regression techniques have been used to examine annual loads in terms of hydrological and morphological characteristics of the headwater catchments.

Based on the field information available, a generalized model for the relationship between suspended sediment concentration and water discharge is described.

Finally, the derived annual loads from the headwater catchments are combined with both limited observations from the larger Sussex rivers and data available for other catchment investigations in the British Isles, to produce a series of prediction equations for catchment yield under temperate climatic conditions.
Mangos shale‐associated alluvium
Authors: Laronne Jonathan B.
Published: February 2007

Inquiry into the dissolution kinetics of naturally occurring geologic materials, rather than individual mineral species, has been relatively neglected. This is especially true of surface processes, the realm of surface water hydrology and geomorphology. This paper focuses attention at a laboratory study of the rate of such complex reactions.

Functions defining the dissolution rates of saline (0.1–20 per cent salt content) Mancos Shale‐associated alluvium in distilled water follow varying patterns. Dissolution is characterized by an initial (<5 min) high rate constant, by a following phase (20 min‐57 h) where rates are reduced drastically, and by a final period of encroachment to equilibrium. Initial dissolution rates increase with increase in salt content and sediment: water ratio. The time necessary to approach equilibrium is, however, found to be directly proportional to the sediment; water ratio. The concentration of Na+, Mg2+, Ca2+, SC2−4 and HCO−3, and the relative abundance of Ca2+ and HCO−3 increase continuously with contact time, indicating that the hydrated sodium and magnesium sulphate minerals provide most of the initial solutes, though not necessarily most of the total solute bulk.

The results obtained in this study indicate that the high initial dissolution rate of soluble minerals from alluvium, and particularly from shales in contact with aqueous solutions, is too short‐lived to account for most of the solutes occurring in heavily sediment‐laden surface flow. Excluding input from slower, usually supersaturated subsurface flow, dissolution from sediment in transport should be a major source of solutes in originally undersaturated and kinetically unequilibrated surface water in semiarid and arid regions.
The effect of a new zealand beech forest canopy on the kinetic energy of water drops and on surface erosion
Authors: Mosley M. P.
Published: February 2007

Rain and throughfall drops were sampled during rain events in a New Zealand beech forest and the frequency distributions of drop mass and kinetic energy calculated. The kinetic energy of throughfall under the canopy was always greater than that of rainfall in the open, notwithstanding interception losses. During a typical rain event in which 51 mm fell in 36 h, the total kinetic energy of throughfail was 1.5 times greater than that of rainfall, and the mean amount of sand splashed from sample cups was 3.1 times greater under the canopy than in the open. It appears that where mineral soil is exposed at the surface, by animal trampling or burrowing for example, rates of soil detachment by splash under a forest canopy will probably exceed those in the open.
The geormorphology of subalpine snow avalanche runout zones: San juan mountains, colorado
Authors: Huber Thomas P.
Published: February 2007

A comparison was made between the distal ends of twenty‐two avalanche and fifteen non‐avalanche slopes in the San Juan Mountains of Colorado, U.S.A. All slopes occurred in the subalpine zone. Six characteristics were used for analysis: type of slope, surface material, longitudinal profile, perched debris or debris tails, avalanche impact on opposite valley wall, and transverse profile. Both fan and roadbank avalanche slope types were found along with the non‐avalanche slopes. Almost all slopes were turf covered rather than talus since the work was done below treeline. Twenty avalanche slopes had a distinctive concave longitudinal profile. Little debris of any kind was found since the slopes were in an area of insignificant amounts of detritus. Many of the larger and two of the smaller avalanche slopes showed evidence of impact upon the opposite slope. Eighteen of the avalanche slopes had convex transverse profiles.
Asymmetry of river channel cross‐sections: Part II. mode of development and local variation
Authors: Knighton A. D.
Published: February 2007

A five‐stage model of the development of cross‐sectional asymmetry is proposed in which alternating bar deposition and bed scour are important elements. Quasi‐periodic reversals in the sense of asymmetry and a progressive increase in the magnitude of asymmetry at sections which develop an asymmetry initially are major features of the model. Application of Bridge's (1977) model confirms several features of the model and suggests that the degree of asymmetry is directly related to bend curvature. After the initial stages, subsequent changes to the cross‐sectional and planimetric form of the channel may be intensified by the developing asymmetry through a system of positive feedbacks in which the levels of form and flow distortion are interrelated. Asymmetry appears to provide an important link between cross‐sectional and plan form adjustment.

Spatial series of asymmetry obtained for three lengths along a mountain stream contain features predicted by the model. In particular, the dominant peak in spectral density functions occurs at a frequency with a corresponding wavelength close to 4πw which has significance in terms of the meander wavelength‐width relationship (Richards, 1976a). This consistency is remarkable considering local differences. In addition, sections in curved reaches tend to be more asymmetric, especially when sited at pools. However, contrary to expectation, channel width is not significantly correlated with asymmetry.
Aspect‐induced differences in hillslope processes
Authors: Churchill Robert R.
Published: February 2007

The type and relative rate of geomorphic process activity on residual hillslopes in the White River Badlands of South Dakota were found to vary as a function of aspect‐induced differences in topoclimate. Drainage densities on north‐facing slopes several orders of magnitude greater than those on slopes facing south indicate that north‐facing slopes experience greater fluvial erosion. Comparative analysis of mass movement features suggests that north‐facing slopes are prone to relatively high‐magnitude, low‐frequency failures, whereas south‐facing slopes experience far more frequent but much smaller movements.

Variations in process activity can be explained in large part by aspect‐induced differences in moisture regime. Field monitoring of moisture conditions indicates that north‐facing slopes maintain higher and less variable moisture levels. South‐facing slopes are not only drier in‐ general but are subject to more frequent and intense episodes of wetting and drying. Differences in moisture conditions promote differences in weathering activity as evidenced by thicknesses of slope regoliths. Higher moisture levels on north‐facing slopes lead to more rapid dissolution of binding cements and consequently, thicker regolith covers. On south‐facing slopes, however, regolith covers are virtually non‐existent due to both drier conditions and episodic desiccation, which triggers small rockfalls. Greater fluvial erosion on north‐facing slopes is a consequence of higher antecedent moisture levels, which retard infiltration. Further, the unconsolidated regolith cover is more erodible than the relatively unweathered materials exposed on the surfaces of south‐facing slopes. Resistance to slumps and mudflows is lower on north‐facing slopes because the weathered regolith is less cohesive than the unweathered parent material and also because the regoliths are periodically saturated.
A wave tank experiment on the erosional mechanism at a cliff base
Authors: Sunamura Tsuguo
Published: February 2007

A laboratory experiment using a two‐dimensional wave tank was designed to investigate the mechanism of erosion at a cliff base by waves armed with rock fragments. The experiment was performed under constant wave conditions by systematically changing the amount of beach sand at the foot of steep model cliffs of the same slope and strength. Cliff erosion occurred when the beach material at the cliff/beach junction was moved by waves. Turbulence created by bores rushing up on the beach mobilized the sand and exerted a mechanical shearing force on the cliff face using the sand as an abrasive. The analysis of results indicated that the effect of the abrasive doubled when the cliff/beach junction was located above Still Water Level (SWL) as compared to when it was below SWL. The assailing force of the sediment‐laden water masses was proportional to the square of the bore speed immediately in front of the cliff face. The factor of proportionality is related to the quantity of beach sand entrapped in the turbulent fluid.
Small channels: Their experimental formation, nature, and significance
Authors: Moss A. J. , Green Patricia , Hutka J.
Published: February 2007

The manner in which small channels are generated, from plane beds beneath sheet flows, has been experimentally elucidated. On plane, erodible, sand beds, the transition from thin, supercritical sheet flows to the channelled condition was studied over ranges of discharge, slope, and temperature. Secondary flow of the second kind, its action facilitated by steep vertical velocity gradients in the primary flows, caused sheet‐flow instability. Along junctions between neighbouring secondary cells, both either raised or lowered elements of the primary flow. In the latter case, fast surface water was lowered to the bed, causing relatively intense, local, longitudinal scour. Dislodged grains were moved divergently to either side, leaving straight, central trenches. Development of positive feedback between cells and trenches led to rapid enlargement of the latter and concomitant growth of paired levees. The resulting structures, ‘protochannels’, were themselves ephemeral, developing two types of instability associated with secondary flow of the first kind. Firstly, small deviations from bilateral symmetry were enhanced, causing evolution into meandering channels. Secondly, headcutting led to multiple tributary development and, at resulting confluences, the action of strong pairs of secondary cells led to the development of braiding channels. Because they are shortlived, protochannels are but rarely seen in nature. Their seeding is markedly temperature‐sensitive, reflecting their frictional origin.

The erosive power of shallow overland flow largely depends on flow‐energy concentration by secondary flow, firstly into channels, then within the channels themselves. Suppression of secondary flow, as by intense raindrop bombardment, can stabilize sheet flows.

In deeper water, the effects of secondary flow appear relatively less dramatic. However, even if such motion is weak, bedload divergence from attachment lines can favour entrainment locally and thus affect bed geometry. Analogy between our results and river behaviour appears close and. on continental shelves where water must often flow as sheets, structures resembling giant protochannels evidently persist.
The relation of chain length to chain curvature in natural channel networks
Authors: Abrahams Athol D.
Published: February 2007

Analyses of three different areas indicate that chain curvature controls chain length indirectly through valley‐side plan form. It follows that, since concave chains on one side of a stream are usually matched by convex chains on the other side, tributary development and abstraction do not occur independently along either side of a stream, as has hitherto been assumed.
Discussion of: Experimental test of autosuspension (southard and mackintosh, 1981)
Authors: Parker Gary
Published: February 2007

The use of a pipe‐flow experiment for testing autosuspension criteria is criticized. It is argued that the proposed criterion for autosuspension is a necessary but not a sufficient condition, and that an analysis of turbidity currents can fill this gap.
The contribution of throughflow to storm runoff: An evaluation of a chemical mixing model
Authors: Anderson M. G. , Burt T. P.
Published: February 2007

The contribution of throughflow to storm runoff is examined using a chemical mixing model. The results predict that throughflow is an important component of storm runoff particularly during the period of stream recession. Supporting hydrological data suggests that a major throughflow input occurs coincident with the stream discharge peak. The two sets of results therefore conflict in the predicted timing of the throughflow response.
Dunes on the skeleton coast, Namibia (South West Africa): Geomorphology and grain size relationships
Authors: Lancaster N.
Published: February 2007

Simple, and locally compound, transverse and barchanoid dunes dominate the 2000 km2 Skeleton Coast dunefield in northwestern Namibia/South West Africa. Dune height and spacing are closely correlated (r = 0‐89) and decrease across the dunefield from southwest to northeast, with an accompanying change from transverse to barchanoid ridges and ultimately barchans.

The dunes are aligned transverse to the dominant strong south and south southwest onshore winds. Alignment patterns indicate that surface roughness changes between coastal plain and dunes cause dune‐forming winds to swing to the right over the dunes, but resume their original direction beyond.

Grain size and sorting vary at three scales: the dune, the dune landscape and through the dunefield. Overall the sands, derived from three localities by deflation from beaches supplied by vigorous longshore drift, become progressively finer and better sorted across the dunefield paralleling changes in dune height and spacing.

A statistically significant relationship (r = −0−65) was established between dune spacing and the phi grain size of the coarser fraction of the dune sands, demonstrating the importance of the protective effects of coarse grains, and suggesting that the morphometry of simple transverse dunes may be controlled by the scale of turbulence associated with the threshold wind speed required to move the coarsest fraction of the dune sand.
Grand canyon—a quantitative approach to the erosion and weathering of a stratified bedrock
Authors: Aronsson Gunnar , Linde Krister
Published: February 2007

A new method is proposed for solving a differential equation arising from weathering‐limited development of a valley. Allowance is made for horizontal stratification and overhang can be allowed to develop. The model is applied to the Grand Canyon and comments are included on its relevance.
Threshold of coarse sediment transport in broad and narrow natural streams
Authors: Carling P. A.
Published: February 2007

The threshold of coarse sediment transport has been examined in natural streambeds in an upland Pennine (U.K.) area. Threshold values of the total boundary shear stress (T0) (for a given grain size), in a narrow natural stream (W/D < 11) are considerably higher than values of T0 in a broad stream (W/D > 11). Efficiency in the entrainment process is related not only to the overall channel geometry, but also varies as a function of discharge in channels characterized by compound roughness.

Empirical curves relating T0 and a mean grain size (d5) are presented, but are limited in application to streams of similar physical and hydraulic characteristics as the ones examined in this investigation. Considerable divergence is noted between these empirical functions and a summary empirical function for general application obtained from a published source. The reasons for this divergence are discussed.

The influence of grain shape was found not to be important in the initiation of motion criterion. This conclusion may reflect the limited range of natural grain shapes in the study streams, but might reasonably apply to other field investigations of similar streams.

Modifications of the Shields' and Yalin diagrams are suggested for practical applications in shallow streams with poorly‐graded bed material. The Shields' parameter may be regarded as an inverse function of the relative protrusion of individual grains in the shallow flow depth (d5/D). The increased importance of augmented drag forces, in the entrainment process in shallow flows, is suggested as the physical explanation for the reduced values of the Shields' parameter. However, the relationships presented should not be applied to laboratory experiments concerned with well‐graded sediments (therefore beds with little deviation in level), in which the Shields' parameter may be regarded as constant at high Reynolds' grain numbers.

Consistent estimated field values of ϵ, a threshold sediment transport parameter, might be used to compare field data to threshold values derived from statistical arguments and laboratory experiments reported in the literature.
Temporal variations in bedload transport rates: The effect of progressive bed armouring
Authors: Gomez Basil
Published: February 2007

The 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

The 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

A 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

An 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

The 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

Epithelial 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

Within 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

Microglia, 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

The 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

Sensitive 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

Rapid 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

‘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

Ambiguity 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

Release 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

Discharge 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

It 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.
One year irrigation experiment to assess losses and runoff volume relationships for a residential road in hertfordshire, England
Authors: Hollis G. E. , Ovenden J. C.
Published: February 2007

Six sections of a residential road (75 mm bituminous macadam over 200mm lean mix concrete over 100 mm hoggin with a recent surface dressing of 10 mm granite chippings and K1‐70 binder) that drain to individual instrumented gully pots were irrigated along the kerb and then over the whole road approximately monthly for a year. The aim was the determination of terminal infiltration losses, initial losses, percentage runoff, and infiltration curves for the kerb and road surface. The results were not as expected from the literature.

There is an annual cycle of infiltration losses at the kerb with a winter peak caused by frost action that is 3.2 times greater than the terminal loss rate at kerbs in summer. The terminal loss rate for an ‘average catchment’ was 6.4251 min−1 from the road surface and 14.251 min−1 in summer and 46.281 min−1 in winter at the kerb. Evaporation was usually more than an order of magnitude less significant than infiltration.

The wide variation in initial losses before runoff commenced was inexplicable. Two sections of road behaved in the classic manner with initial losses averaging 0.8 mm, two other catchments had highly variable initial losses in the range 1.2 to 8.8mm, and the last two pieces of road were even more erratic.

The percentage runoff for those irrigations of over 15 mm of equivalent rainfall was never more than 10 per cent. The maximum per cent runoff was around 50 per cent following 10 mm of equivalent rainfall for kerbside irrigation and only 5 mm of irrigation over the whole road. There were no significant simple or multiple regression relationships between percentage runoff from the kerb or the whole road irrigations and irrigation amount, slope, UCWI, and SMD.

Infiltration curves, for kerb and road irrigation, were so diverse that they do not represent the ‘simple impervious surfaces’ envisaged at the start of the experiment and described in the literature. Since the artificial irrigation of kerbs and roads has failed to substantiate existing theory, these experiments should be repeated at a variety of sites with a high rate of irrigation.
Three instruments used in rainfall—runoff simulation experiments
Authors: Kai Wu , Changming Liu
Published: February 2007

Three instruments recently developed for use in the Runoff Formation Laboratory of the Institute of Geography, Academia Sinica are briefly described. The experimental data obtained indicate that all of them meet the design requirements and they are being successfully used in the Laboratory.
Chloride in precipitation and streamwater for the upland catchment of river severn, mid‐wales; some consequences for hydrochemical models
Authors: Neal Colin , Christophersen Nils , Neale Richard , Smith Christopher J. , Whitehead Paul G. , Reynolds Brian
Published: February 2007

Variations in the concentration of Cl in rainfall and stream runoff are presented for two catchments in the Hafren forest of mid‐Wales, Great Britain. Despite the large fluctuations in rainfall concentrations, Cl in the streamwater remains relatively constant. Using the two‐reservoir Birkenes model, an attempt was made to simulate observed Cl in streamwater. The original model was unable to reproduce the observations and several modifications are suggested to provide better simulations. The resulting model is not the only one capable of reproducing the observations; other hydrochemical models will most probably also achieve this although emphasis will in each case be placed on different aspects. In this paper, it is suggested that the stochastic properties of water movement and chemical processes can account for the streamwater chemistry responses observed. On the catchment scale these processes will lead to an apparently deterministic behaviour that may well be described by simple relationships.