bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic Stimulation of the Left Vagal Nerve in Children: Effect on Swallowing
Authors: Schallert Gloria , Foster Jeffrey , Lindquist Nancy , Murphy Jerome V. 
Published: August 2005

Summary: Purpose: To learn whether stimulation of the left vagal nerve would influence swallowing. Methods: Eight children receiving intermittent left vagal nerve stimulation (VNS) for their pharmacoresistant epilepsy underwent barium swallow studies with their generators off, on, and at maximally tolerated settings. Results: Laryngeal penetration of barium was present in three patients without stimulation, and was caused by VNS in one other patient. Aspiration never occurred. Conclusions: Stimulation of the left vagal nerve under conditions used to treat epilepsy does not cause aspiration.
Evidence of Enhanced Kindliig and Hippocampal Neuronal Injury in Immature Rats with Neuronal Migration Disorders
Authors: Germano Isabelle M. , Sperber Ellen F. , Ahuja Shalini , Moshé Solomon L. 
Published: August 2005

Summary: Purpose: Neuronal migration disorders (NMD) are often found in patients with epilepsy. However, the mechanisms linking these two pathologies are not yet fully understood. In this study, we evaluated whether NMD increased kindling seizure susceptibility and seizure‐induced acute neuronal damage in the immature brain. Methods: Experimental NMD were produced by exposing pregnant rats (gestation day 15) to methylazoxymethanol acetate (MAM, 25 mg/kg, ip). Seizures were induced in rat pups (postnatal day 15) transplacentally exposed to MAM and controls by hippocampal kindling. Afterdischarge (AD) threshold and duration, seizure stage, and number of stimulations required to reach each seizure stage were recorded. Acute seizure‐induced damage was histologically assessed in Nissl‐stained and silver‐impregnated hippocampal tissue 24 h after kindling. Results: Rat pups with NMD had a significantly lower AD threshold than controls (91 ± 18 vs. 163 ± 23 μA; p < 0.05). Furthermore, rats with NMD required fewer stimulations to reach seizure stage 3.5 and 4 than did controls. Additionally, rats with NMD had longer AD the second day of stimulation (2,094 ± 416 s vs. 1,755 ± 353 s; p < 0.05). Histologic examination revealed that in rats with NMD, acute seizure‐induced neuronal hippocampal damage occurred bilaterally in CA3 hippocampal neurons. Conclusions: The lowered AD threshold and more rapid kindling to stages 3.5 and 4 indicate that in the presence of severe NMD, hippocampal kindling is facilitated. Furthermore, this study suggests that in the immature brain, seizure‐induced hippocampal neuronal damage occurs if there is an underlying pre‐existing pathology.
Chronic Intracranial EEG Monitoring for Localizing the Epileptogenic Zone: An Electroclinical Correlation
Authors: Schiller Yitzhak , Cascino Gregory D. , Sharbrough Frank W. 
Published: August 2005

Summary: Purpose: To evaluate the diagnostic yield and identify predictive factors of the surgical outcome in patients with intractable partial epilepsy undergoing chronic intracranial EEG monitoring (CIEM). Methods: The clinical, magnetic resonance imaging (MRI) and electrophysiologic data of 108 patients that underwent CIEM were retrospectively reviewed. The discharge pattern and spatial extent of the initial ictal discharge were determined by blinded visual inspection and computerized analysis. Results: The main predictive indicator for epilepsy surgery outcome in patients that underwent CIEM was the presurgical MRI findings. Most patients with hippocampal atrophy or complete lesionectomy were rendered seizure free after epilepsy surgery (83 and 80%, respectively), whereas only a small minority of patients with partial lesipectomy or no detected MRI lesion had seizure–free operative outcomes (21 and 22%, respectively). Multifocal independent initiation of the initial ictal discharge was associated with a poor surgical outcome. In contrast, the pattern and local spatial extent of the initial ictal discharge observed with CIEM failed to predict the surgical outcome. Conclusions: The main predictor of the surgical outcome in patients that underwent CIEM was the MRI findings, whereas CIEM had only limited use in localizing the epileptogenic zone in the absence of an MRI lesion. The reported findings indicate a low specificity of CIEM in defining the site of seizure onset, which in turn significantly impairs the reliability of CIEM in delineating the epileptogenic zone for epilepsy surgery. Further studies are required to define the indications and patient sub–populations who can benefit from CIEM before epilepsy surgery.
Double‐Blind, Placebo‐Controlled, Lamotrigine in Treatment‐Resistant Generalised Epilepsy
Authors: Beran R. G. , Berkovic S. F. , Dunagan F. M. , Vajda F. J. E. , Danta G. , Black A. B. , Mackenzie R. 
Published: August 2005

Summary: Purpose: Lamotrigine (LTG) is recognised as effective add‐on therapy for focal epilepsies, but this is the first double‐blind, placebo‐controlled, crossover study in treatmentresistant generalised epilepsy. Methods: The study consisted of 2 × 8‐week treatment periods followed by a 4‐week washout period. Patients received doses of either 75 or 150 mg daily, depending on their concomitant antiepileptic drugs (AEDs). Long‐term continuation was offered at the end of the study with open‐label LTG. Results: Five centres in Australia recruited 26 patients who were having absence, myoclonic, or generalized tonic‐clonic seizures or a combination of these. Twenty‐two patients completed the study. There was a significant reduction in frequency of both tonic‐clonic and absence seizure types with LTG. A 250% decrease in seizures was observed for tonic‐clonic seizures in 50% of cases and for absence seizures in 33% of evaluable cases. Rash was the only adverse effect causing discontinuation. Twenty‐three of 26 opted for open‐label LTG, with 20 still receiving LTG for a mean of 26 months. In these 20, 80% had 250% seizure reduction and five (25%) were seizure free. Conclusions: This study shows that LTG is effective add‐on therapy in patients with refractory generalised epilepsies. Statistically significant reduction in seizures in both absence and tonic‐clonic seizure types was seen even with low doses of LTG.
Infiltration and Hydraulic Conductivity of a Compacted Earthen Liner
Authors: Albrecht K. A. , Cartwright K. 
Published: August 2005

ABSTRACTInfiltration through a small (3 × 9 × 1 m) experimental earthen liner, similar to those used for waste disposal was evaluated. The liner was constructed using full‐size compaction equipment, and in‐situ ponded infiltration rates were measured using two large (1·5‐m diameter) sealed double‐ring infiltrometers. An average apparent steady‐flux density of 1·5 × 10−7 cm/s was achieved after two to three weeks. Wetting front depths of 7·3 cm and 9·6 cm after 46 days were calculated assuming a Green‐Ampt piston flow infiltration system. One of the infiltrometers was ponded with water containing rhodamine dye and after the 46‐day infiltration test, a uniform rhodamine dye front was observed at about the 4‐cm depth. Sharpness of the dye front suggests that the piston flow assumption is a reasonable one. Apparent saturated hydraulic conductivity of the liner was estimated from the infiltration data to be no more than 3·6 × 10−8 cm/s, meeting the present EPA permeability requirement for earthen liners of no more than 1 × 10−7 cm/s. Transit time for the wetting front to reach the liner bottom at the 0·91‐m depth was predicted to be about three years. Seepage flux after liner saturation was estimated at 4·8 × 10−8 cm/s for a liner ponded with 30 cm of water.
Creation of an Artificially Produced Fracture Zone to Prevent Contaminated Ground‐Water Migration
Authors: Begor Kristen Franz , Miller Michael A. , Sutch Rodney W. 
Published: August 2005

ABSTRACTRecovery of contaminated ground water in a fractured bedrock system presents some unique problems. Typically, the most common problem occurs from the inability to adequately characterize the discrete fractures through which contaminants may be migrating. Without adequate characterization, difficulties arise in properly positioning recovery wells and verifying the performance of the system. To overcome these difficulties at a site in Upstate New York, an innovative approach was developed involving the creation of an artificial fracture zone through controlled blasting to intercept contaminated ground‐water flow.Site investigations delineated the extent of a ground‐ water contamination plume migrating within a fractured bedrock aquifer (Medina sandstone) which underlies approximately 15 ft of glacial till. A 72‐hr aquifer test involving one recovery well resulted in a low yield (3.5 gpm with 20 ft of drawdown). Data collected from adjacent observation wells indicated poor interconnection among the naturally occurring fractures. Although the response of some observation wells mirrored that of the recovery well, others showed little or no response to pumping. Therefore, achieving the corrective action objectives (i.e., preventing further contaminant migration and removing and treating contaminated ground water) would be difficult using a “traditional” multiple recovery well system. It was decided that controlled linear blasting could provide the enhanced fracture interconnection necessary to successfully intercept the contaminated ground‐water plume, which would then be captured and removed by judicious placement of recovery well(s) installed within the fracture zone.Using a carefully controlled single line pattern blasting technique, a 6‐ft wide, 300‐ft long fracture zone was created in the upper 25 ft of the bedrock aquifer perpendicular to the centerline of the plume. Following fracturing, a second 72‐hr aquifer test was conducted at the same location and under conditions similar to the first test. The second test indicated that the single recovery well located in the newly created fracture zone should be fully capable of recovering contaminated ground water and preventing further migration of the plume. The recovery well produced a substantially higher yeild of 18.5 gpm with only 11.2 ft of drawdown. Futhermore, all of the nearby observation wells showed significant response to pumping.Success at this site is promising, and the approach may prove useful at other sites involving contaminated bedrock aquifers.
Determination of Aquitard/Aquiclude Hydraulic Properties from Arbitrary Water‐Level Fluctuations by Deconvolution
Authors: Neuman Shlomo P. , Gardner David A. 
Published: August 2005

ABSTRACTA deconvolution method is proposed for the estimation of aquitard/aquiclude vertical hydraulic diffusivities on the basis of water‐level measurements in piezometers completed both in the confining layer(s) and in neighboring aquifers. The water levels may fluctuate in an arbitrary manner which is not necessarily caused by a prescribed pumping regime (as required in conventional pumping tests). A simple formula from the literature can be used to correct the measured water levels for time lag in the piezometer response. If the specific storage of the confining material is known from laboratory consolidation tests, the hydraulic diffusivity estimates can be translated into vertical hydraulic conductivities. The method is illustrated with the aid of a case study from southern California and is shown to yield robust parameter estimates.
Modeling Ground‐Water Management Options for Small Limestone Islands: the Bermuda Example
Authors: Thomson James A.M. 
Published: August 2005

ABSTRACTSmall oceanic limestone islands represent a unique hydrogeological environment. High transmissivities and small land areas cause the average water‐table relief to be of the order of cm, while permitting larger diurnal and barometric sea‐level changes to penetrate the aquifer. Extremely accurate surveying and monitoring at observation wells and tedious data reduction are necessary to obtain representative water levels.Numerical modeling of island aquifers, while largely in its infancy, can be an excellent focus for research, and ultimately a useful management tool. Essential inputs to an island model are barometric changes in oceanic base level and a thorough assessment of recharge.In Bermuda, the main ground‐water lens provides 4500 m3/d of ground water for public supply. Because of the importance of this resource, the Bermuda Public Works Department has invested in a ground‐water monitoring and research program. As part of this, a well‐evaluated example of an island aquifer model has been developed.Bermuda is generally typical of this hydrogeological environment, but differs from other small islands in two ways: (1) internal marshes, major discharge areas elsewhere, act as barriers to ground‐water flow; and (2) development of a high density of housing (typical of only a few small oceanic islands) has significantly increased Bermuda's recharge, because of domestic waste water and road drainage contributions.A number of aquifer management options were tested by the Bermuda model. Steady‐state modeling results suggest that an increase in abstraction to 8500 m3/d without serious derogation is possible. Such a policy would increase the vulnerability of the lens to point‐source pollution, and should therefore be gradual, monitored, and combined with stronger measures for pollution prevention.
The Geohydrology of Mars
Authors: Risner Jeffrey K. 
Published: August 2005

ABSTRACTThe recent advances in space science have now made it possible to construct models of the existence. volume, and hydrologic cycle of the ground water of the planet Mars.Outgassing models of water vapor indicate that the surface of Mars should be covered with water to a depth of 10 to 100 meters (1·4 × 1015 to 1·4 × 1016m3). Geomorphic evidence suggests a depth of at least 500 meters (7 × 1016 m3) of water should occur over much of the planet, yet no surface water, other than glacial ice at the poles (2·3 × 1015 to 9 × 1015 m3), exists today. Martian gravity, though only 40 percent of Earth's, would keep water from escaping the planet. A survey of surface and atmospheric water volumes indicates that the majority of water, 1·2 × 1016 to 6 × 1016 m3, is hidden as ground water.Hydrologic cycle models indicate that Mars has an active but near static hydrologic cycle, dominated by water discharge in desert lowlands and water recharge at the ice‐ covered poles. Ground‐water flow plays a major role in this system.
Characterization of Ground‐Water Flow by Field Mapping and Numerical Simulation, Ross Creek Basin, Alberta, Canada
Authors: Ophori D. U. , Tóth J. 
Published: August 2005

ABSTRACTHydrogeological mapping and numerical simulation techniques have been used to characterize the flow of ground water in Ross Creek Basin, Alberta, Canada. Forty percent of the basin's ground water is recharged in the Cypress Hills and discharged through local, intermediate, and regional flow systems at lower topographic elevations north of the hills. The remaining 60 percent is recharged through randomly distributed areas of restricted sizes. The similarity between the flow patterns mapped in the field and simulated numerically is an indication that the mapping technique is useful in determining ground‐water flow patterns throughout the various climatic regions in the Alberta prairies. Ground‐water discharge was found not to be restricted to the thalwegs of the main drainage ways, Ross and Gros Ventre Creeks, and their tributaries. Consequently, measurable base flow cannot represent the total discharge of ground water, which is estimated to be 2·0 × 10−4 m3/s or 22 percent of the total precipitation in the basin. There is evidence that soil development has been influenced by ground water in this area.
Preliminary Evaluations of Regional Ground‐Water Quality in Relation to Land Use
Authors: Cain Doug , Helsel Dennis R. , Ragone Stephen E. 
Published: August 2005

ABSTRACTThe U.S. Geological Survey through its Toxic‐Waste— Ground‐Water Contamination Program began studies during 1984 to evaluate the degradation of regional ground‐water quality as a result of human activities. The studies are designed to quantitatively relate human activities, expressed as land use, to the quality of ground water at a regional scale.Preliminary results from six of the studies in New York, New Jersey, Connecticut, Florida, Nebraska, and Colorado summarized in this paper indicate that regional ground‐water quality has been affected by human activities. The frequencies of detection of volatile organic compounds and some trace elements were larger in ground water underlying urban or industrial areas in comparison to undeveloped areas. Ground water in agricultural areas generally had larger concentrations of nitrate and had an increased frequency of detection of pesticides in comparison to undeveloped areas. Effects of human activities on water quality increased as the intensity of urbanization or irrigation increased. Ground‐water pumpage, waste‐water discharges into a stream that is hydraulically connected to an alluvial aquifer, and consumptive use of ground water affected the ground‐water quality in one study area to a greater extent than land‐use practices.These preliminary results indicate that in specific areas, surficial nonpoint sources, expressed as land use, have altered regional ground‐water quality. Additional studies are being made to determine if these results are consistent and widespread.
Storage Basin Volume and Drainage Basin Dynamics: Camas Prairie, South‐Central Idaho
Authors: Cluer Brian L. 
Published: August 2005

ABSTRACTA recent tectonic model and subsequent gravity survey and basement modeling have raised questions concerning the size of the Camas Prairie ground‐water storage basin and the hydrodynamic properties of the Camas Creek drainage basin. This paper addresses storage basin dimensions using an anomalous mass determination from a plot of residual gravity, and presents estimates of recharge and underflow from a mass‐balance study. Underflow may transport much of the water [2·73 (105) acre‐feet/yr] (ac‐ft/yr) calculated as residual in the mass‐balance study, and transport is from the Camas Prairie storage basin south to the Snake Plain Aquifer via permeable strata in the Mount Bennett Hills surface drainage divide. Results of the anomalous mass study suggest that the volume of ground water stored in the Camas Prairie basin is 39 (106) ac‐ft, considerably greater than previously estimated. Similarly, recharge to the Camas Prairie basin is estimated at over 7(105) ac‐ft/yr, one order of magnitude greater than earlier estimates.
Unified Management of Surface‐ and Ground‐Water Quality Through Clean Water Act Authorities
Authors: Duda Alfred M. 
Published: August 2005

ABSTRACTExisting institutions for protecting surface‐ and ground‐water quality provide uneven results across the nation. Pollutants are transferred across media and political boundaries, important contaminants are not addressed, important sources of pollution are not controlled, and accountability in achieving measurable objectives is not assured. Examples from the seven‐state region served by the Tennessee Valley Authority (TVA) document the wide range of ground‐water contamination issues facing the nation and the importance of interconnections between subsurface and surface waters–both hydrologically and institutionally. National legislation seems imminent to overcome institutional barriers that promote fragmented, ineffective, and expensive approaches.Unified management of subsurface‐ and surface‐water quality makes both hydrologic and institutional sense for dealing with cross‐media, cross‐agency linkages causing water pollution. Congressional testimony presented by TVA suggests that this unified water quality management can be achieved through a narrow amendment to the Clean Water Act requiring state adoption of (1) surface‐ and subsurface‐water classification systems, (2) surface and subsurface numerical standards, and (3) conjunctive surface‐ subsurface‐water quality management programs. National minimum program requirements, federal funding, and federal program/facility compliance would provide leadership in creating new local/state/federal partnerships targeted to priority geographic areas. In this way, the state comprehensive program would become the hub around which the spokes of all different environmental and natural resource management (technology‐based control) programs with surface‐ or ground‐water quality implications would be integrated. This proactive water quality management approach would be less costly to the public than existing reactive approaches which have left taxpayers with a half trillion dollar remedial action bill for cleaning up our surface‐ and ground‐water resources.
Correlations of Permeability and Grain Size
Authors: Shepherd Russell G. 
Published: August 2005

ABSTRACTPrevious theoretical and empirical investigations of the relation between particle size and intergranular permeability have resulted in the well‐known formula for intrinsic permeability (k)
image

where d is particle diameter, and c is a dimensionless constant. Statistical power regression analyses were per‐ formed on 19 sets of published data on size and laboratory permeability of unconsolidated sediments. The exponent of grain diameter ranged from 1.11 to 2.05, but most values were significantly less than 2.0. Results indicate that the permeability/grain size relation alternatively may be expressed, from an empirical basis, as

image
Values of c and the exponent both generally decrease with decreased textural maturity and increased induration.
Shape Factors for Permeability Tests in Boreholes and Piezometers
Authors: Chapuis Robert P. 
Published: August 2005

ABSTRACTSeveral sets of values are available for the shape factor of the cylindrical injection zone used to perform a field permeability test. Depending on the selected value, the resulting difference for hydraulic conductivity may reach 40% for long intake zones, and more than 100% for short intake zones. The commonly used shape factor is that given by Hvorslev (1951). Seven other factors derived from numerical models are now available: they differ from Hvorslev's factor by up to 100%. Three possible reasons for the differences are examined. Reference is made to Laplace's equation and related mathematical results derived before 1945. Shape factor values obtained by numerical methods are shown to be more or less accurate solutions of particular cases when impervious or recharging boundaries exist close to the injection zone. Their influence upon the shape factor value can be calculated analytically, as shown in a detailed example. Analytical shape factor equations are given for a cylindrical injection zone with either a pervious or an impervious bottom. Based on the method of image wells, two other equations are established to correct the shape factors if draining (constant head) or impervious layers are known to be located close to the injection zone. These equations should be used for field permeability tests in boreholes or piezometers.
Modeling Transport of a Degradable Chemical and Its Metabolites in the Unsaturated Zone
Authors: Tim Udoyara S. , Mostaghimi Saied 
Published: August 2005

ABSTRACTA mathematical model for transport and transformation of a pesticide and its metabolites in the soil is presented. Mechanisms for convective‐transport, hydrodynamic dispersion, ionic exchange, biological degradation, and hydrolysis are accounted for in the mathematical formulation. The major assumptions used in developing the model include: flow in the soil is in the vertical direction and one‐ dimensional, soil system is homogeneous and isotropic, volumetric water content and Darcy's flux are constant in time and space, and a linear reversible Freundlich isotherm describes the concentrations in the aqueous and adsorbed phases. Based on the outlined assumptions and Laplace transform techniques, analytical solutions for the concentrations of the parent material and its metabolites are presented. The applicability and potential of the model are demonstrated by predicting the transport and transformation of aldicarb (a nematicide of agricultural significance) and its metabolite, aldicarb sulfoxide, in the soil.