Abstract Groundwater models are used to manage water resources in carbonate aquifers throughout the UK. These models often utilize non-linear modifications of equivalent porous media (EPM) assumptions to simulate the observed head-flow relationships. This paper describes the application of similar principles to time-variant water balance modelling of a karstified aquifer: the Carboniferous Limestone in SW England. The non-linear model successfully simulates the large changes in bulk hydraulic conductivity required to adequately model flows from two karstic spring catchments. Model results illustrate that the rate of drainage from the vadose zone is affected by the extent and thickness of soil cover. In a catchment with mixed soil cover, vadose zone drainage is shown not to be significant in sustaining summer low flows at the spring. The performance of the model is limited in some cases: summer storm flows in particular are poorly simulated. The limitations suggest that the true response of the system is dependent on recharge intensity (rate) as well as antecedent water levels and that the EPM assumption of good connection between conduits and the diffuse flow zone is not always valid in this aquifer. This may have implications for groundwater model design in other carbonate aquifers.

Igumale shale and its inclusion were analyzed using scanning electron microscopy (SEM) with its accessory, energy dispersive X-ray (EDX) system. The samples were also subjected to transmission electron microscopy (TEM) while subsidiary chemical analyses were made for allophane test. X-ray diffraction (XRD) and X-ray fluorescence (XRF) tests were conducted on the samples to complement the findings of the electron microscopy. The shale was found to have a general open structure with a crinkled lettuce effect, which suggests the appearance of montmorillonitic or mixed-layer clay. The inclusion was identified to be gypsum. It is concluded that the underlying shale was responsible for cracks on the floors and walls of buildings in the study area. The results also explain the very considerable broadening of peak in the X-ray diffraction pattern. Keywords: Microscopy, X-ray, Shale, Analysis, Diffraction.Global Journal of Engineering Research Vol. 7 (1) 2008: pp. 29-36

A study was undertaken to determine the geotechnical properties of Makurdi shale. Seven disturbed soil samples were collected from two sites in Makurdi and subjected to engineering classification tests and X-ray diffraction analysis. Results of the simple index tests suggest that the soils have medium to high swelling potential while X-ray diffraction analysis showed that the soils contain a high percentage of mixed-layer illite/smectite, high percentage of kaolinite and a small percentage of illite. The mineralogical analyses explained the expansive nature of the soil and suggest the causes of cracks in buildings. Ten disturbed soil samples were collected from a third site of a proposed site for a light building and subjected to engineering classification tests. Based on the outcome of the second set of experiments, a foundation other than the conventional strip footing was proposed and constructed. The performance of the foundation was observed for 5 cycles of rainy and dry seasons and found to be very satisfactory; as very few cracks were observed compared to light buildings founded on similar sites. It can be concluded that the proposed foundation appears to be suitable for light buildings on expansive clays and is therefore recommended as a solution to the problem of foundations on such soils.

Thirty-one undisturbed samples were collected from depths of 1.5 to 3.0 m on clayey hill slopes in the Pliocene and Allochthonous geological formations of Tuscany and Abruzzi in central Italy. Thin sections were made from each of the samples and the micromorphological aspects described semi-quantitatively using both microscopic and image analyses. The results were compared with the three, broad hill slope profiles – straight, convex and concave. The study showed that hill slope evolution by both creeping and surface and subsurface runoff has changed the conditions within the clay fabric and that linear voids due to tension and shear processes have formed in the soil. The data suggest that clayey hill slope form evolves from convex to concave via a linear shape.

Geothermal convection of seawater deep in carbonate platforms could provide the necessary supply of magnesium for dolomitization at temperatures high enough to overcome kinetic limitations. We used reactive-transport simulations to predict the rates and spatial patterns of dolomitization during geothermal convection in a platform that was 40 km across and 2 km thick. In the simulations, porosity and permeability decrease with depth to account for sediment compaction.Dolomitization of a platform consisting of medium grained (similar to0.05 mm) sediments occurred in a broad band ranging from similar to2.5 km depth near the margin to similar to1.5 km depth near the platform center. The area of dolomitization is deep enough that temperatures exceed similar to50degreesC but not so deep that low permeabilities restrict mass transport. Complete dolornitization in the center of this zone is estimated to require at least 60 my. Incorporation of permeability contrasts, permeable beds, and reactive beds focused dolomitization strongly and reduced the estimated time required for dolornitization by as much as 50 percent. Dolomitization created magnesium-depleted, calcium-rich fluids in less than 10 ky, and results support a link between dolomitization and anhydrite precipitation where adequate sulfate is available.

Geothermal convection in carbonate platforms could drive massive dolomitization by supplying mass transport of magnesium over long periods and at temperatures high enough to overcome kinetic limitations. Reactive-transport simulations based on Enewetak Atoll show dolomitization in a thin band at a permeability contrast near the base of the platform, which is consistent with field observations of dolomitized Eocene deposits. Dolomitization is predicted at approximately 6% per My at temperatures of 45–60°C, and complete dolomitization could be accomplished in ∼16My. Calcium enrichment of pore fluids and upward transport of these fluids is established early, prior to 30ky.

Two types of regional-scale seawater circulation have been proposed to explain the formation of Enewetak Atoll dolomites: geothermal and reflux circulation. We have used a finite element groundwater flow model to examine the pattern, magnitude and dynamic interaction of these two different circulation mechanisms in Enewetak Atoll. Geothermal circulation is concentrated around the atoll-margin whereas refluxing mesosaline brines flow from the atoll interior towards the margin to restrict and eventually shut off geothermal circulation. Refluxing brines of 36–80‰ can account for the salinity signature recorded in dolomite fluid inclusions. Distributions of fluid flux and Mg mass-balance calculations suggest that both geothermal and reflux circulation mechanisms could account for the observed distribution of dolomite in Enewetak Atoll. Furthermore, the atoll interior may be extensively dolomitized as observed in other atolls.

We have used a new coupled two-dimensional diagenetic and sedimentological model to investigate the evolution of a simple aggrading carbonate platform subject to glacio-eustatic sealevel fluctuations, The model employs variable hydrological zones, internally defined from platform exposure and climate, to provide a framework within which diagenetic processes are simulated at specified rates. Simulations show a clear stacked sequence of diagenetic zones, which are readily recognizable because of their lateral continuity and distinct trends in diagenetic evolution from platform interior to margin. However, spatial associations between unconformity surfaces and underlying diagenetic zones that suggest causality are misleading. The interaction between high amplitude sea-level fluctuations and subsidence results in substantial overprinting and a complex diagenetic history that could not be unraveled by traditional stratigraphic and sedimentological methods.

Arabian Archaeology and EpigraphyVolume 7, Issue 2 p. 214-239 Husn Awhala: A late prehistoric settlement in southern Fujairah D.T. POTTS, Corresponding Author D.T. POTTS School of Archaeology, The University of Sydney, NSW AustraliaAddress: D. T. Potts School of Archaeology University of Sydney NSW 2006 AustraliaSearch for more papers by this authorL. WEEKS, L. WEEKS School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorP. MAGEE, P. MAGEE School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorE. THOMPSON, E. THOMPSON School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorP. SMART, P. SMART School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this author D.T. POTTS, Corresponding Author D.T. POTTS School of Archaeology, The University of Sydney, NSW AustraliaAddress: D. T. Potts School of Archaeology University of Sydney NSW 2006 AustraliaSearch for more papers by this authorL. WEEKS, L. WEEKS School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorP. MAGEE, P. MAGEE School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorE. THOMPSON, E. THOMPSON School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this authorP. SMART, P. SMART School of Archaeology, The University of Sydney, NSW AustraliaSearch for more papers by this author First published: November 1996 https://doi.org/10.1111/j.1600-0471.1996.tb00102.xCitations: 3Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume7, Issue2November 1996Pages 214-239 RelatedInformation

The combination of synchronous rotation of the polars in an optical microscope and digital image analysis provides orientation distributions and detailed maps of the directions of orientation in the micrographs. La combinaison de la rotation synchrone des pol-ariseurs d'un microscope optique et de l'analyse d'image digitalisée permet d'obtenir la distribution des orientations et des cartes détaillées des directions d'orientation.

Primary linitis plastica carcinoma of the colon is an uncommon morphological type of colorectal carcinoma. Linitis plastica of the stomach may spread to the colon producing a similar lesion to primary colonic linitis plastica. This case report describes a case of linitis plastica of the colon that had many of the clinical, endoscopic, radiological and operative features of Crohn's colitis. The precise origin of the linitis plastica carcinoma was not clear: it may have been clonic or gastric, although the former is favoured. This case illustrates a number of facets of this unusual colonic carcinoma.

In studying soil microstructure, the orientations of soil particles and of the voids between them are two of the most important factors. In this Paper, the directed vein method and the convex hull method are proposed for automatic orientation analysis of soil microstructure. In the directed vein method a directed vein image of the boundaries of the particles in an electron micrograph of soil structure is constructed using a chain code, and the expected directions of a directed vein are calculated to provide the orientation of the vein. In the convex hull method simple polygons are constructed from the boundaries, the convex hulls of the simple polygons are built up, and the longest diagonal of each convex hull is selected, the direction of which is taken as the orientation of the particle. Before either method can be applied, image preprocessing must be carried out to find the boundaries of the particles. Both methods involve simpler programming, faster computing and less storage than do other methods. Les orientations des particules du sol et des vides entre ces particules représentent deux des facteurs les plus importants dans I'étude de la microstructure des sols. L'article propose pour I'analyse automatique des orientations dans la microstructure des sols une méthode dite à veine dirigée et une méthode dite à enveloppe convexe. Dans la méthode à veine dirigée on construit, à I'aide d'un code à chaîne une image à veine dirigée des limites des particules dans un micrographe électronique de la structure du sol, après quoi on calcule les directions attendues d'une veine dirigée pour fournir I'orientation de la veine. Dans la méthode à enveloppe convexe on construit des polygones simples à partir des limites, on construit des enveloppes convexes de polygones simples et on choisit la diagonale la plus longue de chaque enveloppe convexe, sa direction est admise comme I'orientation de la particule. Avant I'application de I'une ou de I'autre de ces méthodes il faut prétraiter I'image afin d'obtenir les limites des particules. En comparaison avec d'autres méthodes, ces deux méthodes présentent I'advantage de programmes simplifiés, de calculs plus rapides et de mémoires réduites.

SUMMARY Samples from 70 horizons from UK soils were tested for structural stability, and a comparison was made between the results from the following six tests: (i) Emerson, (ii) Janse & Koenigs, (iii) Thorburn, (iv) Childs (soil moisture characteristic), (v) Williams & Cooke slump test, and (vi) wet sieving. Both correlations and systematic differences were observed between the tests, suggesting that different aspects of stability were emphasized by different test procedures. The tests leading to classes (i), (ii) and (iii) were found to be more subjective than those leading to indices. It is suggested that (v) may be applicable to less stable soils, and (vi) to more stable soils. Childs’ test was time consuming and subject to some erratic results; two new indices of stability are proposed to increase the reliability of this test.

Understanding the rheology of colloidal suspensions is crucial in the formulation of a wide selection of industry-relevant products, such as paints, foods and inks. To characterise the viscoelastic behaviour of these soft materials, one can analyse the microscopic dynamics of colloidal tracers diffusing through the host fluid and generating local deformations and stresses. This technique, referred to as microrheology, links the bulk rheology of fluids to the microscopic dynamics at the particle scale. If tracers are subjected to external forces, rather than freely diffusing, it is called active microrheology. Motivated by the impact of microrheology in providing information on local structure in complex systems such as colloidal glasses, active matter or biological systems, we have extended the dynamic Monte Carlo (DMC) technique to investigate active microrheology in colloidal suspensions. The original DMC theoretical framework, able to accurately describe the Brownian dynamics of colloids at equilibrium, is here reconsidered and expanded to describe the effects of an external force pulling a tracer embedded in isotropic colloidal suspensions at different densities. To this end, we studied the dynamics of a spherical tracer dragged by a constant external force through a bath of spherical and rod-like particles of comparable size. We could extract valuable details on its effective friction coefficient, being constant at small and large values of the external force, but otherwise displaying a nonlinear behaviour that indicates the occurrence of a force-thinning regime. Our DMC simulation results are in excellent quantitative agreement with past Langevin dynamics simulations and theoretical works for the bath of spherical colloids. The bath of rod-like particles is studied in the isotropic phase, and displays an example where DMC is more convenient than Brownian or Langevin dynamics, in this case, in dealing with particle rotation.

Females of Dacus tryoni, booby-trapped by topical application of 400 µg of N,N'-tetramethylenebis( 1-aziridinecarboxamide), sterilized males with which they copulated. Sterility in the males was complete and persisted for at least 10 days after mating contact. Booby-trapped females were less attractive to males than untreated females when the sterilant was applied before the flies reached sexual maturity. Attractiveness was not significantly impaired when the females were treated after reaching sexual maturity. Sterile males were as effective as fertile males in winning mates. The introduction of a small proportion (one-tenth) of booby-trapped females into a cage population caused a considerable drop in overall fertility, but the sterilant was probably spread more by attempted matings rather than by actual copulation.

Of a number of candidate sterilants tested against Dacus tryoni, three mutagens (HMPA, TEPA and TMAC) were effective against both sexes. With HMPA the margin between sterilizing and lethal doses was narrow, but with the others it was wide. Males sterilized by HMPA or TEPA taken by mouth were slightly less effective than untreated males in securing mates. Males sterilized by TMAC applied topically appeared to be hypercompetitive, but this result was probably caused by the sterilant having been spread to the untreated flies with which they were caged. Reserpine produced a slight reduction in both the fecundity and fertility of the females. With repeated application, ketodecenoic acid slightly reduced female fecundity, but two other growth regulators β-ecdysone and the juvenile hormone analogue Altosid, were ineffective.

N,N'-tetramethylene-bis-(1-aziridinecarboxamide), applied topically, sterilized male and female Lucilia cuprina (Wiedemann) at a dose of 10 µg per fly. Females tolerated 800 µg per fly. A female 'booby-trapped' with 400 µg of sterilant could transfer a sterilizing dose to a male during copulation. Booby-trapped females were sexually attractive and sterile males were as sexually vigorous as fertile males. The introduction of either booby-trapped females or sterilized males into cage populations caused a greater drop in fertility than expected, but the effect was probably due more to unspecific contact between flies than to mating contacts.

An approximate analysis of the deformation of an ideal model of weathered rock, consisting of cubical blocks of intact rock set in a continuous clay matrix, leads to expressions for the anisotropic constitutive constants of an equivalent continuum in terms of the degree of weathering. The rigidity of the massif is seen to decrease rapidly during the early stages of weathering. A comparison with some field data is included; and the analysis is extended, tentatively, to the onset of yield.