bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of soil compaction parameters by means of Atterberg limits
Authors: Al-Khafaji A. N.
Published: November 2007

This Technical Note examines the relationship between the Atterberg limits and soil compaction as measured by use of the standard proctor compaction test. The relations of liquid limit,
W
L
, and plastic limit,
W
p
, to proctor maximum dry density,
P
d
, and optimum moisture content,
W
opt
, are determined quantitatively for soils from Iraq and USA. Using curve fitting techniques, empirical equations are derived and charts are prepared. From these it is possible to estimate the potential optimum moisture content and maximum dry density for standard proctor compaction from the knowledge of Atterberg limits only. The accuracy of these charts is considered in relation to the basic data. The compaction parameters of the Iraqi and the United States soils are also compared.
Some hydrogeophysical properties of the Chalk of Humberside and Lincolnshire
Authors: Barker R. D.
Published: November 2007

The results of laboratory measurements of various hydrological and physical properties of the Chalk of Lincolnshire and Humberside are presented. The measured parameters include density, porosity, hydraulic conductivity and formation factor. The equations governing their inter-relationships have been determined. Examination of the manner in which these properties vary with stratigraphic level shows that porosity increases upwards from the stratigraphic base of the Chalk while density and formation factor decrease.
Groundwater modelling with limited data: a case study in a semi-arid dunefield of northeast Nigeria
Authors: Carter R. C. , Morgulis E. D. , Dottridge J. , Agbo J. U.
Published: November 2007

Groundwater and other hydrological models are usually used only in situations where large amounts of historical and spatially distributed data are available. There are however good arguments for using models (a) to test conceptual models and assess the controls on system behaviour, and (b) to assist in planning data collection. The paper describes the application of a finite difference groundwater model to an area of dune fields and oases in northeast Nigeria. Limited field data provided inputs and the basis for calibration of the model, and model output gave useful insights into the functioning of the hydrological system. Conclusions are drawn on overall system behaviour, the relative merits of different recharge hypotheses (specifically addressing the controversy over whether present groundwater levels are the result of current recharge or fossil gradients), and the requirements for future data collection and monitoring.
Discussion on ‘Acidisation: borehole development and rehabilitation’
Authors: Banks D. , Cosgrove T. , Harker D. , Howsam T. , Thatcher J. P.
Published: November 2007

R. A. Monkhouse writes: This paper essentially states that for borehole development, simply to remove the wall-cake (slurry) from a freshly constructed (Chalk) well, very much smaller quantities of hydrochloric acid are required than are generally employed in this form of borehole development. It is also said that, when larger quantities are used, these are to develop fissures in the surrounding aquifer rather than to remove wall-cake. What is not said is what amount of acid should be used (in particular, the borehole depth is not considered) and how to define the circumstances in which the lesser treatment is preferable to the larger. Stow & Renner (1965) recommended an injection of 20 kg (rounded to the nearest kilogram) per square metre of wall face exposed within the saturated chalk in order to remove the wall-cake. This ratio was determined for an acid strength of 30° Twaddell. for treatment of the aquifer, no particular amount of acid was recommended, but there was an implication of some 2 to 2½ times the volume of water contained within the borehole below the plain lining tubes. I have been able to identify in the Geological Survey well record collection five of those boreholes listed in Table 1 as having been acidised commercially (which I call here group A), and all seven of those treated by the Anglian Water staff (Group B). From these records, I obtained additional details of depth, length of lining tubes and depths to rest water level and from these calculate
Dispersive soils: a review from a South African perspective
Authors: Bell F. G. , Maud R. R.
Published: November 2007

Dispersive soils deflocculate in the presence of relatively pure to form colloidal suspensions and are therefore highly susceptible to erosion and piping. Such soils contain a higher content of sodium in their pore water than other soils. However, there are no significant differences in the clay contents of dispersive and non-dispersive soils. Unfortunately no one test is successful in identifying these soils in every instance. Because the principal chemical factors influencing dispersive behaviour in a soil are exchangeable sodium and cation exchange capacity, these two parameters are frequently used in South Africa to help distinguish between dispersive and non-dispersive soils. Nonetheless it is recommended that more than one test is used to identify these soils and pehaps a rating system could be adopted. Dispersive soils are widely distributed in South Africa and are derived from a variety of rock types. They are commonly found in regions where the annual rainfall is less than 850 mm. Suspicion of their presence is indicated by the occurrence of erosion gullies and piping. In some parts of South Africa dispersive soils have to be used for construction purposes since no other soil material is available. Hence dispersive soils have been used in the construction of earth dams and embankments. Serious piping and failures have occurred, especially when they have been used for earth dams. However, if an earth dam is properly constructed, incorporating filters, impermeable core and, in particular, correctly compacted, then it should perform satisfactorily. Dispersive soils sometimes can be stabilized by treatment with lime or gypsum.
Mechanical properties of jet grouted soilcrete
Authors: Fang Yung-Show , Liao Jyh-Jong , Lin Ta-Kang
Published: November 2007

To investigate the mechanical properties of jet grouted soilcrete, uniaxial compression tests, Brazilian tests and ultrasonic tests were conducted on a number of samples. It was found that the uniaxial compressive strength, modulus of elasticity, failure strain, tensile strength and P-wave velocity of soilcrete increase with increasing dry density. Dry density should be one of the critical criteria to control the quality of jet grouting. Significant variation of strength was monitored for soilcrete from the same depth because of the non-uniform mix of soil and grout with a high-pressure jet. The maximum axial and lateral strain at failure were found to be 0.62% and 0.20%, respectively. These values are relatively close to the failure strains for concrete, rather than for soil. The Brazilian tensile strength varied between 1/10 and 1/30 of the uniaxial compressive strength.
The effect of crystal size on geotechnical properties of Neogene gypsum in Crete
Authors: Papadopoulos Z. , Kolaiti E. , Mourtzas N.
Published: November 2007

The gypsum deposits to the southwest of the city of Heraklion, northern Crete, have been widely used as a construction material from early times either as structural or ornamental stone or foundation rock. In the study area, they were exploited and used extensively for the construction of the Knossos Palace. Although gypsum is considered as a basically weak and soluble material, it has withstood the test of time and the occasional failure problems have been observed only recently after the excavations and especially after the completion of the early restoration works. The paper attempts to highlight the geotechnical properties of gypsum and relate them to the various gypsum formation mechanisms and environments.
Estimating aggregate properties from the unconfined compressive strenght of rock
Authors: West Graham
Published: November 2007

A method is given for estimating the aggregate strength properties from the unconfined compressive strength of rock. It is envisaged that this will prove useful to those who may wish to infer aggregate properties from rock strength data in site investigation reports, in the absence of aggregate test results.
Discussion on ‘Engineering Geology of North Lantau’ by C. A. M. Franks & N. W. Woods
Authors: Franks C. A. M. , Woods N. W.
Published: November 2007

M. D. Howat writes: The authors' review is admirably complete yet makes no mention of the sensitivity of the marine clays, especially in relation to the problems posed by the so-called “lower marine deposits” which could be attributed either to the base of the Hang Hau or the top of the Chek Lap Kok Formations.

The sensitivity of the marine soils of Hong Kong, first reported by Holt (1962), was noted in North Lantau boreholes by Fung
et al.
(1984) and observed in situ by Howat (1985, 1987) in excavations and tunnels for the Island Line of the Hong Kong Mass Transit Railway. The sensitivity can be gauged on Fig. 1 which compares the Chek Lap Kok liquidities with those of the sensitive clays analysed by Skempton & Northey (1952). There was at the time of publication some discussion on its engineering significance (Endicott 1984; Howat 1984).

While this sensitivity may not pose a particular problem for the very weak upper marine deposits, whose yield stresses are exceeded during large-scale reclamation allowing consolidation to occur (Koutsoftas & Cheung 1985), it could be vital for the stiffer lower marine deposits whose higher yield stresses are approached, but not exceeded, and can therefore find themselves in a rather delicate metastable condition after a considerable thickness of fill has been placed. The gradual breakdown of the resulting highly stressed soil structure with time can explain the 'stagnation of pore pressure dissipation' (continuous regeneration of excess pore pressures?) to which the authors allude.

The
Review of Transport Research Laboratory research on highway drainage
Authors: Farrar D. M.
Published: November 2007

Drainage measures are an important means of ensuring the stability of highways and associated structures. Much of the TRL research on highway drainage has been directed towards examining the field performance of drainage systems, usually over extended periods. This paper describes studies mainly by TRL on edge of pavement drainage, slope drainage, drainage to retaining structures, and drainage blankets. The results are described in relation to current UK practice.
Swelling behaviour of calcareous clays from the Eastern Province of Saudi Arabia
Authors: Abduljauwad S. N.
Published: November 2007

The development of heave and swelling pressure in the natural calcareous expansive soils in the Eastern Province of Saudi Arabia causes major damage to structures constructed on or in them. The behaviour of expansive soil depends on the predominant type of clay minerals present, the cementing agents that bind these clay minerals and other physical and chemical properties. This paper presents the problems and the geotechnical and physicochemical properties of the calcareous expansive soil deposits in the Eastern Province of Saudi Arabia. X-ray, thermal and chemical analyses and scanning electron microscopy were used to estimate the type and quantity of clay and non-clay minerals and fabric of the investigated soil. The swelling potential was determined using a conventional oedometer test. A field test conducted for measurement of heave was compared with heave estimated from laboratory- tests, Results showed that the investigated soil had moderate to very high swelling potential and the heave estimated from the suction method was very close to the value measured from the field test.
Landslide and erosion hazard mapping at Ok Tedi copper mine, Papua New Guinea
Authors: Hearn G. J.
Published: November 2007

Landslides and erosion pose significant hazards to mining and engineering activity in the remote mountainous terrain of Western Province, Papua New Guinea. The investigation and containment of these hazards have been the concern of the Ok Tedi open-cast copper mine since engineering feasibility studies began in 1978. Subsequent terrain hazard mapping has identified numerous landslides and rock avalanche deposits in the Ok Tedi catchment and in the immediate vicinity of the mine, ranging from very low frequency, catastrophic rock avalanches through to mudslides and mudflows that recur on a daily or weekly basis. This mapping formed part of a multidisciplinary geotechnical study instigated by Ok Tedi Mining Limited and comprised detailed slope inventory, geomorphological mapping combined with air photograph interpretation nd a review of pre-existing structural geological and geotechnical data. The study area was sub-divided into 245 zones and assigned hazard and risk categories or levels derived from the field data. These classifications were presented in map form at 1:10 000 scale along with prioritized recommendations for further investigation, monitoring and remedial action, where appropriate.
The geomorphological controls on seismically triggered landslides during the 1908 Straits of Messina earthquake, Southern Italy
Authors: Murphy W.
Published: November 2007

Investigation of landslides which have been located from contemporary accounts of the Straits of Messina earthquake of 1908 reveals that a failure envelope for the slopes may be drawn on the basis of slope height-slope angle relationships for static and dynamnic stresses. As would be expected there is a decrease in stability during the earthquake to a degree which is almost certainly linked to the generation of pore water pressures. However, a region of the failure envelope shows much greater decrease in stability; this section of the curve describes the stability of low slope height-high slope angle forms. The area for which this stability curve has been calculated is affected by a nearfield earthquake. It is suggested that these slopes are suffering from forced vibration from high-frequency accelerations. In support of such a hypothesis of a geomorphological control is the observations that many of the landslides along this section of coastline occurred at topographic irregularities.
Engineering performance of some coarse-grained arid soils in the Libyan Fezzan
Authors: Fookes P. G. , Gahir J. S.
Published: November 2007

Arid engineering soils are those whose properties have been conditioned by an arid climate: they differ from soils in temperate or humid climates mainly in the role played by water. In temperate climates coarse-grained materials having less than 12 0.000000ines will generally behave as free draining soils. This case study shows that in a hot desert environment some sands with up to 30 0.000000ines, of low plasticity or no plasticity, also demonstrate behaviour which is consistent with that of free draining soils.

The near-surface materials studied were the subject of a small investigation by the contractor during Phase II of the Great Man-made River Project, Libya. They were mainly rounded to subrounded granular particles resulting from mechanical action of wind and water. The particles are predominantly limestone and quartz fragments derived from the local Cretaceous and Palaeocene shallow marine, carbonate-rich bedrock sources: mid-Tertiary basic volcanics and younger Tertiary continental deposits also contribute.

Windblown, mainly carbonate, silt-sized dust is characteristic of the local desert conditions. It is generally angular and often mixed with the sands. Occasional wetting and subsequent evaporation have resulted in a very weak cementation (calcite and occasionally gypsum) of the granular particles. This holds the grains, preventing them from being free-flowing, and the resulting soil has some special properties, including for example, large variations in grain size distribution between dry and wet sieving; low plasticity index of the fines in predominantly granular soils; high dry density upon compaction and good load bearing characteristics.

These sands are considered typical of hot arid, coarse grained deposits in a carbonate rich geomorphological environment. Vast areas of sands in the Middle East and elsewhere with carbonate bedrocks are likely to be similar to these and their behaviour is also likely to be influenced by a carbonate fines content.
Effect of fly ash with lime and cement on the behavior of a soft clay
Authors: Indraratna A. S. , Balasubramanian A. K. , Khan M. J.
Published: November 2007

The effect of fly ash on the strength and deformation characteristics of Bangkok clay is discussed in the paper. Lime or cement has been added as secondary constituents to further enhance self-hardening of the blended mix. For example, unconfined compression tests reveal that after two weeks of curing, a 18 0.000000ly ash and a 5 0me treated Bangkok Clay attains a compressive strength 2-3 times greater than that of the natural clay. However, if lime is replaced by cement, the initial rate of strength development increases significantly. Excessive fly ash contents (greater than 25%) cause tensile splitting of unconfined specimens. The compressibility of fly ashcement treated soil is considerably less than that of the natural clay. As the fly ash content exceeds 10 0.000000or a constant cement content of 5%, the increase of the equivalent yield pressure becomes significant. The reduction in compressibility is also associated with a corresponding increase in the coefficient of consolidation. The triaxial tests confirmed that fly ash-lime and fly ashcement treated specimens indicate a much higher sheafing resistance by improving the apparent friction angle, although the effect on the cohesion intercept is marginal. The stressstrain response changes from a normally consolidated state to an over-consolidated state as a function of the fly ash content. The findings of this study present a rational basis for the development of appropriate constitutive models for chemically modified soils.
Engineering geology of the Bukit Timah Granite for cavern construction in Singapore
Authors: Zhao J. , Zhou Y. , Sun J. , Low B. K. , Choa V.
Published: November 2007

The Bukit Timah Granite forms one-third of the surface area of Singapore. In recent studies, the engineering geology and hydrogeology as well as the rock mass properties of the granite formation were investigated to assess its potential as a host medium for large rock caverns. This paper presents the results of the recent field and laboratory investigations, including engineering and mechanical properties, weathering characteristics, discontinuity systems, groundwater regime and general rock mass quality. The results conclude that the Bukit Timah Granite has good potential for underground cavern construction.
The survey and recording of historic monuments
Authors: Emerick Keith
Published: November 2007

Historic monuments are a valuable asset and provide information on man's past activities. They also provide the engineering geologist with useful guidance on rates of weathering. Man has, at a known time, taken rocks from the ground and combined them with other building materials such as mortars and renders. All of these materials have been exposed to weathering, which is now well advanced in some stones or structures. The work of the conservation bodies records,
inter alia
, the present status of the weathering process.

The photographs were all taken at Fountains Abbey, near Ripon in Yorkshire. The Abbey was founded in 1132 but has been without a roof or windows since the Dissolution of the Monasteries in 1539. Some remarkable contrasts in weathering are apparent. The severe weathering shown in Fig. 4 is probably related to winds coming in through the large open East window; conversely the render and limewash seen in Fig. 7 is still in very good condition after over 400 years of exposure, albeit in a less exposed location. The records of such a building provide documentation on rates of weathering in engineering time, and also provide insights into the effect of various processes on a range of different materials.

The obligation to record historic monuments satisfies a number of criteria. The survey produced is known as an ‘as found’ record of the building, i.e. its appearance before works take place. This can be used as a record of archive standard and also as the base for detailing
Engineering in weathered rock
Authors: Hencher S. R. , McNicholl D. P.
Published: November 2007

The potential problems to be faced when engineering in zones of weathered rock are reviewed. Difficulties in formulating realistic geotechnical models by standard methods of site investigation and routine testing are emphasized and the consequences of being wrong are illustrated by examples. Alternative approaches for delineating weathered zones for design are presented. The constraining influence of particular characteristics of weathered zones on methods of construction are discussed with reference to brief case histories.
The Erzincan Earthquake, Friday, 13 March 1992
Authors: Hencher S. R. , Acar I. A.
Published: November 2007

A shallow (15 to 30 km) magnitude (M
s
) 6.8 earthquake occurred on 13 March 1992 close to Erzincan city in northeast Turkey (Fig. 1). The earthquake caused the deaths of over 500 people together with severe damage to many thousands of properties. Erzincan is sited towards the northern edge of the alluvial plain of the River Euphrates; the basin is infilled with hundreds of metres of sediments and surrounded by mountains which rise to more than 3000m to the north and south (Figs 2 & 3). The geology and evolution of the basin are described by Barka & Gülen (1989). Peak measured accelerations at the meteorological station, close to the centre of Erzincan, were approximately 0.5
g
(E-W), 0.4
g
(N-S) and 0.25
g
vertically. Predominant periods were 0.31 s (E-W), 0.95 s (N-S) and 0.16 s (vertical) (EEFIT 1992).

The earthquake was focused on the North Anatolian Fault (NAF), shown in Fig. 4. Damage was highly localized within the region. As indicated in Fig. 2, the majority of damage from the earthquake occurred within a narrow zone, south of, and parallel to, the NAF, yet north of the epicentre. Close to the city centre, many municipal, concrete framed buildings of more than three storeys such as schools, public housing and hospitals, were severely damaged (Figs 5 & 6). However, vertical cuttings through silty sands with some clay, in the same area, survived with little apparent distress (Fig. 7). To the north of the city, on rising ground, concrete-framed and more flimsy
Honeycomb weathering of Carboniferous sandstone in a sea wall at Weston-super-Mare, UK
Authors: Pye K. , Mottershead D. N.
Published: November 2007

Blocks of Forest of Dean Stone, an arkosic, clay-rich sandstone of Lower Carboniferous age, which were used in the construction of a sea wall at Weston-super-Mare in the 1880s, now display extensive honeycomb weathering features. Spatial variations in the degree of weathering, together with geochemical evidence, suggest that marine salt spray has played a key role in the development of the honeycombs. Petrographic microscope and SEM studies indicate that the principal weathering mechanisms involved are granular disintegration and micro de-lamination induced by chemical alteration along inter-grain boundaries and differential swelling and contraction of clays within the rock.

Salt crystallization and hydration pressures within the rock pores appear to have played a minor role in this case. The formation of alveoli has been favoured by initial irregularities on the surfaces of the stone blocks which allowed differential ingress and retention of saline solutions. Progressive enlargement of the alveoli continues until the boundary walls between adjacent cavities are breached and the honeycomb layer disintegrates. Over the past century the maximum rate of surface lowering of the honeycombed surfaces at Weston-super-Mare has exceeded 1 mm a
-1
.
Three-dimensional geomodelling for offshore aggregate resources assessment
Authors: Orlić B. , Rösingh J. W.
Published: November 2007

Use of a three-dimensional geoscienfific modelling system in offshore sand resources analysis is described. The benefits of a three-dimensional approach to geological modelling are that geologists can concentrate on geological interpretation without the constraints embodied in a two-dimensional approach and geological models can be used directly for aggregate volume assessment, in terms of global and local estimates, with no need to construct isopachytes. An algorithm has been developed which, on the basis of the geological model and variable extraction criteria, yields parameters required for detailed extraction design: depth of dredging, volume of aggregate and ratio of aggregate to waste in the total extracted volume. In addition, the algorithm also accepts as input a three-dimensional geostatistical model of aggregate resource. Data from an offshore site investigated in relation to land reclamation for the Chek Lap Kok Airport, Hong Kong, are modelled, and results are presented for demonstration.
Borehole performance in alluvial aquifers: particulate damage
Authors: Blackwell, I. M. , Howsam P. , Walker M. J.
Published: November 2007

Particulate damage is often cited as a cause of permeability impairment around boreholes, producing a decline in well performance. The mobility of particles within a formation, with respect to both damage and recovery mechanisms, is not easy to quantify

Removal of such damage from the formation has been attempted using water and a variety of low concentration drilling fluids. The results demonstrate that, in normal stable media, the fluids' formation sealing properties outwiegh any special viscosity and particle carrying abilities they may have compared to water, even at low concentrations. Only where the medium was fluidized did the polymers show any advantages over water.

Particulate movement and redistribution under borehole operating conditions has been assessed for a range of artificial and natural formations. It has been shown that movement is limited mainly to formations with a bimodal particle size distribution. In formations with a log-normal distribution, particle movement is restricted to all but the finest particles. The key factor governing particle mobility is therefore the structure of the porous medium.

Particulate damage, however caused, cannot always be effectively removed using normal development and rehabilitation techniques, and should therefore be avoided in the first place, by taking greater care during the drilling, sample collection and analysis, design, construction and development of a borehole.
Reappraisal of time-dependent subsidence due to longwall coal mining
Authors: Goulty N. R. , Al-Rawahy S. Y. S.
Published: November 2007

Subsidence due to longwall coal mining may conveniently be considered as taking place in two phases: active subsidence as the face advances, and residual subsidence after it has come to a halt. Published data show that the dynamic subsidence profile at low face advance rates is independent of the advance rate itself. This finding is incompatible with the common practice of modelling subsidence as a simple viscoelastic process. Qualitative consideration of the mechanical processes taking place during active and residual subsidence shows that different timedependent behaviour during the two phases of subsidence is to be expected. We infer from reported observations of timedependent subsidence that the relaxation times involved during active subsidence are of the order of days, whereas the relaxation times involved during residual subsidence are of the order of one year. As different mechanical processes are involved during each phase, one should not attempt to predict the duration of residual subsidence from observations of active subsidence.
The hydrogeology of Western Europe: a basic framework
Authors: Crampon N. , Custodio E. , Downing R. A.
Published: November 2007

The principal hydrogeological provinces are identified and briefly described. The main aquifers are in the Mesozoic and Cenozoic cover which overlies the Hercynian basement. North of the Hercynian Front, an older cover of the Devonian and Carboniferous rocks, resting on Caledonian basement, contains aquifers of secondary importance. Groundwater is a very essential component of freshwater supplies in Western Europe.
Discussion on ‘The Chalk as a karstic aquifer: evidence from a tracer test at Stanford Dingley, Berkshire, UK’
Authors: Banks D. , Davies C. , Davies W.
Published: November 2007

M. Price writes: Banks
et al.
(1995) address the nature of the permeability of parts of the Chalk aquifer, provide useful data from a tracer test, and draw attention to the potential dangers of disposing of agricultural and road run-off to swallow holes. The paper includes a calculation of fissure conductivity and aperture from the results of the tracer test. In this it has to be emphasized that the calculations relate to Darcian flow in an equivalent smooth, plane, parallel-plate opening, not the more likely turbulent flow in a natural fissure. The true average aperture of the fissure is therefore likely to be significantly greater than that calculated (Price 1987, 1996).

The situation described at Stanford Dingely is one where drainage originating from impermeable Tertiary strata flows onto the Chalk and sinks into the aquifer. The majority of active Chalk sinks appear to be of this type; the drainage sinking into them originates as run-off from other strata. Rain falling anywhere on the outcrop of the Chalk is normally able to infiltrate, so water flowing across the Chalk outcrop is almost invariably allogenic drainage or water that has infiltrated the Chalk and emerged as baseflow. Drainage to sinks is therefore a minor component of recharge to the Chalk.

The tracer test undertaken into at Stanford Dingley involved introducing tracer into a known point of entry in the aquifer, and observing its arrival at a known point of emergence. Such tests almost inevitably measure the speed of groundwater movement along a
Land subsidence in drained peat areas of the Province of Friesland, The Netherlands
Authors: Nieuwenhuis H. S. , Schokking F.
Published: November 2007

The Holocene peat areas in the Province of Friesland consisting of peat and clay deposits are used extensively for agriculture and are drained by maintaining a low surface water level in polder ditches. Considerable rates of land subsidence (1 to 12mrrdyear) result from processes such as soil shrinkage, consolidation and peat oxidation, the last named being the major contributor.

In the Province of Friesland studies of the future effects of continuous long-term land subsidence have been made as part of the hydrological masterplan. For these studies the Geological Survey of The Netherlands (RGD) has compiled maps showing the estimated subsidence over a 50-year period for three scenarios of freeboard (difference in elevation between surface water level and the ground surface). Data sources consist of recent ground surface levels measured for the construction of utility lines, to be used for the transport of water, gas or sewage, earlier topographical maps, historical surface water level records and soil profiles.

Maximum estimates for rates of subsidence for peat with and without clay cover have been established by evaluation of the data with subsequent subsidence process analysis for various situations of drainage, duration of drainage, soil and hydrological conditions. Three maps showing the estimated land subsidence over a 50-year period for freeboards of 0.4, 0.8 and 1.2 m have been compiled using a two-dimensional Geographical Information System (2D-GIS), coupled with the RGD database, and have been presented in 1 km2 grids. A comprehensive map of estimated land subsidence is being compiled by the Province, taking into account the actual freeboards at each location. The presented study forms a new approach to the estimation of future land subsidence in peat areas on a regional scale.
The Chalk as a karstified aquifer: closed circuit television images of macrobiota
Authors: Waters A. , Banks D.
Published: November 2007

The use of closed circuit television (CCTV) imaging in the Chalk aquifer of the Thames catchment of southern England, has shed much light on the aquifer's flow mechanisms. CCTV images indicate that flow to a Chalk abstraction borehole is typically via a limited number of highly transmissive solutionenhanced fracture features. These bear some similarities to conduits found in true karstic aquifer systems, and have implications for the modelling of mass transport in the Chalk aquifer. Another feature, typical of karst aquifers, noted during CCTV surveys is the occasional presence of macroscopic biota, arthropods and annelids, apparently inhabiting the Chalk aquifer system.
Aquifers as environments for microbiological activity
Authors: West J. M. , Chilton P. J.
Published: November 2007

The ability of an aquifer to support microbiological activity depends on several factors: the availability of nutrients and energy sources for microbial use; the physical characteristics of the aquifer itself (such as the groundwater flow regime); and the environmental conditions experienced by the organisms (such as temperature and pH). These factors will be reviewed and their implications discussed in relation to groundwater quality and to the geological disposal of radioactive wastes.
Increased Mortality, Postoperative Morbidity, and Cost After Red Blood Cell Transfusion in Patients Having Cardiac Surgery
Authors: Murphy Gavin J. , Reeves Barnaby C. , Rogers Chris A. , Rizvi Syed I.A. , Culliford Lucy , Angelini Gianni D.
Published: November 2007

Background—

Red blood cell transfusion can both benefit and harm. To inform decisions about transfusion, we aimed to quantify associations of transfusion with clinical outcomes and cost in patients having cardiac surgery.

Methods and Results—

Clinical, hematology, and blood transfusion databases were linked with the UK population register. Additional hematocrit information was obtained from intensive care unit charts. Composite infection (respiratory or wound infection or septicemia) and ischemic outcomes (myocardial infarction, stroke, renal impairment, or failure) were prespecified as coprimary end points. Secondary outcomes were resource use, cost, and survival. Associations were estimated by regression modeling with adjustment for potential confounding. All adult patients having cardiac surgery between April 1, 1996, and December 31, 2003, with key exposure and outcome data were included (98%). Adjusted odds ratios for composite infection (737 of 8516) and ischemic outcomes (832 of 8518) for transfused versus nontransfused patients were 3.38 (95% confidence interval [CI], 2.60 to 4.40) and 3.35 (95% CI, 2.68 to 4.35), respectively. Transfusion was associated with increased relative cost of admission (any transfusion, 1.42 times [95% CI, 1.37 to 1.46], varying from 1.11 for 1 U to 3.35 for >9 U). At any time after their operations, transfused patients were less likely to have been discharged from hospital (hazard ratio [HR], 0.63; 95% CI, 0.60 to 0.67) and were more likely to have died (0 to 30 days: HR, 6.69; 95% CI, 3.66 to 15.1; 31 days to 1 year: HR, 2.59; 95% CI, 1.68 to 4.17; >1 year: HR, 1.32; 95% CI, 1.08 to 1.64).

Conclusions—

Red blood cell transfusion in patients having cardiac surgery is strongly associated with both infection and ischemic postoperative morbidity, hospital stay, increased early and late mortality, and hospital costs.
Dynamic Regulation of Phosphoinositide 3-Kinase-γ Activity and β-Adrenergic Receptor Trafficking in End-Stage Human Heart Failure
Authors: Perrino Cinzia , Schroder Jacob N. , Lima Brian , Villamizar Nestor , Nienaber Jeffrey J. , Milano Carmelo A. , Naga Prasad Sathyamangla V.
Published: November 2007

Background—

Downregulation of β-adrenergic receptors (βARs) under conditions of heart failure requires receptor targeting of phosphoinositide 3-kinase (PI3K)–γ and redistribution of βARs into endosomal compartments. Because support with a left ventricular assist device (LVAD) results in significant improvement of cardiac function in humans, we investigated the effects of mechanical unloading on regulation of PI3Kγ activity and intracellular distribution of βARs. Additionally, we tested whether displacement of PI3Kγ from activated βARs would restore agonist responsiveness in failing human cardiomyocytes.

Methods and Results—

To test the role of PI3K on βAR endocytosis in failing human hearts, we assayed for PI3K activity in human left ventricular samples before and after mechanical unloading (LVAD). Before LVAD, failing human hearts displayed a marked increase in βAR kinase 1 (βARK1)–associated PI3K activity that was attributed exclusively to enhanced activity of the PI3Kγ isoform. Increased βARK1-coupled PI3K activity in the failing hearts was associated with downregulation of βARs from the plasma membrane and enhanced sequestration into early and late endosomes compared with unmatched nonfailing controls. Importantly, LVAD support reversed PI3Kγ activation, normalized the levels of agonist-responsive βARs at the plasma membrane, and depleted the βARs from the endosomal compartments without changing the total number of receptors (sum of plasma membrane and early and late endosome receptors). To test whether the competitive displacement of PI3K from the βAR complex restored receptor responsiveness, we overexpressed the phosphoinositide kinase domain of PI3K (which disrupts βARK1/PI3K interaction) in primary cultures of failing human cardiomyocytes. Adenoviral-mediated phosphoinositide kinase overexpression significantly increased basal contractility and rapidly reconstituted responsiveness to β-agonist.

Conclusions—

These results suggest a novel paradigm in which human βARs undergo a process of intracellular sequestration that is dynamically reversed after LVAD support. Importantly, mechanical unloading leads to complete reversal in PI3Kγ and βARK1-associated PI3K activation. Furthermore, displacement of active PI3K from βARK1 restores βAR responsiveness in failing myocytes.
Left Ventricular Untwisting Rate by Speckle Tracking Echocardiography
Authors: Wang Jianwen , Khoury Dirar S. , Yue Yong , Torre-Amione Guillermo , Nagueh Sherif F.
Published: November 2007

Background—

Recent studies validated the measurement of left ventricular (LV) untwisting rate (UR) by speckle tracking echocardiography. A few reports suggest that it may provide additional noninvasive insight into LV diastolic function.

Methods and Results—

Simultaneous echocardiographic imaging and LV pressure measurements (7F Millar catheters) were performed in 8 adult dogs. Loading conditions were altered by caval occlusion, whereas lusitropic state was changed by dobutamine and esmolol infusion. Inferior vena cava occlusion at all experimental stages (baseline, dobutamine, esmolol) led to a significant decrease (
P
≤0.01) in LV end-systolic volume (ESV) and a significant increase in UR (
P
=0.03). The best relation was observed between LV UR and ESV (
r
=−0.8,
P
<0.001). The clinical study was conducted in 67 patients (age 57±17 years, 19 women) undergoing simultaneous right heart catheterization and echocardiographic imaging, with 20 healthy subjects as a control group. There were 34 patients with ejection fraction (EF) <50% (25±9%), and 33 patients with normal EF and diastolic dysfunction (64±7%). Patients with LV systolic dysfunction had a significantly lower UR (−55 ο/s) in comparison with the control group (−89 ο/s) and patients with normal EF (−104 ο/s,
P
<0.05), and the determinants of LV UR were twist, ESV, and τ (r
2
=0.83,
P
<0.001). In patients with diastolic dysfunction and normal EF, twist and ESV were the independent predictors (r
2
=0.71,
P
<0.001).

Conclusions—

LV UR is reduced in patients with depressed EF, but not in those with diastolic dysfunction and normal EF, and is primarily determined by twist and ESV.
Individual Differences in Sentence Comprehension: A Functional Magnetic Resonance Imaging Investigation of Syntactic and Lexical Processing Demands
Authors: Prat Chantel S. , Keller Timothy A. , Just Marcel Adam
Published: November 2007

Language comprehension is neurally underpinned by a network of collaborating cortical processing centers; individual differences in comprehension must be related to some set of this network's properties. This study investigated the neural bases of individual differences during sentence comprehension by examining the network's response to two variations in processing demands: reading sentences containing words of high versus low lexical frequency and having simpler versus more complex syntax. In a functional magnetic resonance imaging study, readers who were independently identified as having high or low working memory capacity for language exhibited three differentiating properties of their language network, namely, neural efficiency, adaptability, and synchronization. First, greater efficiency (defined as a reduction in activation associated with improved performance) was manifested as less activation in the bilateral middle frontal and right lingual gyri in high-capacity readers. Second, increased adaptability was indexed by larger lexical frequency effects in high-capacity readers across bilateral middle frontal, bilateral inferior occipital, and right temporal regions. Third, greater synchronization was observed in high-capacity readers between left temporal and left inferior frontal, left parietal, and right occipital regions. Synchronization interacted with adaptability, such that functional connectivity remained constant or increased with increasing lexical and syntactic demands in high-capacity readers, whereas low-capacity readers either showed no reliable differentiation or a decrease in functional connectivity with increasing demands. These results are among the first to relate multiple cortical network properties to individual differences in reading capacity and suggest a more general framework for understanding the relation between neural function and individual differences in cognitive performance.
Neural Correlates of Morphological Decomposition during Visual Word Recognition
Authors: Gold Brian T. , Rastle Kathleen
Published: November 2007

Considerable behavioral research has demonstrated that the visual word recognition system is sensitive to morphological structure. It has typically been assumed that analysis of morphologically complex words occurs only when the meaning of these words can be derived from the meanings of their constituents (e.g., hunter = hunt + er). However, results from recent behavioral research using the masked priming technique have demonstrated that morphological analysis can occur at an earlier orthographic level, in cases in which the meanings of complex words cannot be derived from their constituents (e.g., corner = corn + er). Here, we combine the logic of behavioral masked priming with the neurophysiological phenomenon of functional magnetic resonance imaging priming suppression to look for evidence of nonsemantic morphological priming at the neural level. Both behavioral and functional magnetic resonance imaging results indicated priming effects associated with the mere appearance of morphological structure (corner—CORN). In addition, these effects were distinguishable from lexical-semantic effects (bucket—PAIL) and orthographic effects (brothel—BROTH). Three left-lateralized occipito-temporal regions showed sensitivity to early morphological components of visual word recognition. Two of these regions also showed orthographic priming (∼BA 37, peak: −48 −60 −17; ∼BA 19, peak: −40 −77 −1), whereas one was sensitive only to morphological similarity between primes and targets (∼BA 19, peak: ∼37 ∼67 ∼7). These findings provide a neurobiological basis for a purely structural morphemic segmentation mechanism operating at early stages of visual word recognition.
Performance Monitoring in the Anterior Cingulate is Not All Error Related: Expectancy Deviation and the Representation of Action-Outcome Associations
Authors: Oliveira Flavio T. P. , McDonald John J. , Goodman David
Published: November 2007

Several converging lines of evidence suggest that the anterior cingulate cortex (ACC) is selectively involved in error detection or evaluation of poor performance. Here we challenge this notion by presenting event-related potential (ERP) evidence that the feedback-elicited error-related negativity, an ERP component attributed to the ACC, can be elicited by positive feedback when a person is expecting negative feedback and vice versa. These results suggest that performance monitoring in the ACC is not limited to error processing. We propose that the ACC acts as part of a more general performance-monitoring system that is activated by violations in expectancy. Further, we propose that the common observation of increased ACC activity elicited by negative events could be explained by an overoptimistic bias in generating expectations of performance. These results could shed light into neurobehavioral disorders, such as depression and mania, associated with alterations in performance monitoring and also in judgments of self-related events.
On the Tip-of-the-Tongue: Neural Correlates of Increased Word-finding Failures in Normal Aging
Authors: Shafto Meredith A. , Burke Deborah M. , Stamatakis Emmanuel A. , Tam Phyllis P. , Tyler Lorraine K.
Published: November 2007

Tip-of-the-tongue (TOT) experiences are frustrating word-finding failures where people are temporarily unable to produce a word they are certain they know. TOT frequency increases with normal aging during adulthood, and behavioral evidence suggests that the underlying deficit is in retrieving the complete phonology of the target word during production. The present study investigated the neural correlates of this phonological retrieval deficit. We obtained 3-D T1-weighted structural magnetic resonance images (MRI) for healthy participants between 19 and 88 years old and used voxel-based morphometry to measure gray matter density throughout the brain. In a separate session, participants named celebrities cued by pictures and descriptions, indicating when they had a TOT, and also completed Raven's Progressive Matrices (RPM), a task that does not involve phonological production. The number of TOTs increased with age and also with gray matter atrophy in the left insula, an area implicated in phonological production. The relation between TOTs and left insula atrophy cannot be attributed to the correlation of each variable with age because TOTs were related to insula atrophy even with age effects removed. Moreover, errors on the RPM increased with age, but performance did not correlate with gray matter density in the insula. These results provide, for the first time, an association between a region in the neural language system and the rise in age-related word-finding failures and suggest that age-related atrophy in neural regions important for phonological production may contribute to age-related word production failures.
Does Social Assistance Recipiency Influence Unemployment?
Authors: Brännström Lars , Stenberg Sten-Åke
Published: November 2007

Has the frequency of unemployment a tendency to increase the number of social assistance recipients, or does the relationship work the other way round? This article utilizes Swedish monthly data on aggregated open unemployment and means-tested social assistance recipiency in the period 1991—2004 and proposes a multiple time-series approach based on vector error-correction modelling in order to distinguish between theories about the direction of influence. First, we show that rates of unemployment and receipt of social assistance are co-integrated. Second, we demonstrate that adjustments to the long-run equilibrium are made through adjustments to the receipt of means-tested social assistance. This indicates that the frequency of social assistance recipiency reacts to changes in unemployment rather than vice versa. It is also shown that lagged changes in the number of social assistance recipients do not predict changes in rates of unemployment in the short term. Together, these findings demonstrate that the number of social assistance recipients does not increase the number of unemployed.