bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of Right Ventricular Pacing in Patients with Dual‐Chamber ICDs
Authors: OLSHANSKY BRIAN , DAY JOHN , McGUIRE MAUREEN , HAHN STEPHEN , BROWN SCOTT , LEREW DARIN R.
Published: March 2006

Background: Unnecessary right ventricular (RV) pacing in patients with implantable cardioverter defibrillators (ICD) may adversely affect heart failure morbidity and total mortality. Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) is a prospective, multicenter, randomized trial evaluating outcomes in ICD recipients programmed to single‐chamber pacing (VVI) versus dual‐chamber (DDDR) pacing with AV search hysteresis (AVSH).

Methods: Patients underwent ICD implant (for standard indications). The ICD was programmed to DDDR with AVSH regardless of any need for pacing. Rate‐adaptive pacing was set at 60–130 ppm with dynamic AV delay from 200 to 90 ms. AVSH was programmed to search every 32 intervals and extend the AV delay by 50%. One week post‐implant patients with ICDs were interrogated to assess the percentage of RV pacing with the expectation that most would have <20% RV pacing and would be randomized into INTRINSIC RV. Early analysis showed that targets for randomization were not met. AVSH parameters were modified under a protocol amendment to increase AV delay extension to 100%. We report findings related to this programming change based upon analyses of (nonrandomized) data pre‐ and post‐amendment.

Results: Twenty‐one percent of patients (n = 314) were enrolled pre‐amendment and 79% (n = 1,216) were enrolled post‐amendment. The mean percentage of RV pacing at the 1‐week visit was 41.4 ± 29.6% pre‐amendment and 14.7 ± 22.6% post‐amendment (P < 0.0001). The proportion of patients eligible for randomization (RV pacing <20% at the 1‐week visit) was 31.2% pre‐amendment and 76.8% post‐amendment (P < 0.0001).

Conclusion: AVSH can dramatically reduce the percentage of RV pacing among ICD recipients.
Simple Diagnosis of Limb‐Lead Reversals by Predictable Changes in QRS Axis
Authors: HO REGINALD T. , MUKHERJI LENA , EVANS G. THOMAS
Published: March 2006

Background: Limb‐lead reversals (LLRs) remain clinically problematic. Because the frontal QRS axis is derived from an equilateral Einthoven triangle and LLRs either rotate (180 ° horizontally (mirror‐image (M)) and/or 120 ° vertically (clockwise (C)/counterclockwise (CC)) or distort the triangle (by forcing a bipolar lead to record across the lower extremities (LE) where electrical potentials approach zero (zero‐potential lead)), we hypothesize that LLR axes changes from a baseline value (n) are predictable.

Methods: Three hundred and sixty ECGs with all 24 limb‐lead combinations from 15 individuals were analyzed. Predicted and actual QRS axes were compared using linear regression.

Results: Twenty‐four lead combinations produced only 12 (11 abnormal) ECG patterns and diagnosis depended upon identifying upper extremity (UE) cable configurations. Predicted formulas for rotation‐type LLR axes (M, C, CC, MC, and MCC) were 180 − n, n − 120, n + 120, 300 − n, and 60 − n, respectively. Corresponding mean differences between predicted and actual values were 4 ± 5 °, 4 ± 2 °, 7 ± 10 °, 5 ± 7 °, and 3 ± 4 ° (all r = 0.99 − 1.00, P < 0.0001). The predicted formula for distortion‐type LLR axes is (zero‐potential lead axis) ± 90 °. Actual mean values for zero‐potential lead I, II, and III were 90 ± 7 ° or 266 ± 17 °, −31 ± 6 ° or 148 ± 14 °, and 26 ± 14 ° or 209 ± 9 °, respectively. The mean difference between predicted and actual values for all LLRs was 5 ± 8 ° (r = 1.00, P < 0.0001).

Conclusions: LLR axes are predictable within an average of 5 °. This might help differentiate an acute axis shift due to an LLR from serious medical conditions that may require treatment.
Comparison of the Healing Mechanisms of Myocardial Lesions Induced by Dry Radiofrequency and Microwave Epicardial Ablation
Authors: DE GOUVEIA ROSA HENRIQUES , MELO JOÃO , SANTIAGO TERESA , MARTINS ANA PAULA
Published: March 2006

Background: Histological assessment of the evolution of lesions induced on a pig's left atrium by microwave (MW) epicardial applications and comparison with dry radiofrequency (RF) lesions.

Methods: MW (40 W, 40 seconds) and dry RF (80°C, 2 minutes) were epicardially applied on nine pigs' left atrium. Samples were procured following application (n = 2), at day 3 (n = 2), day 7 (n = 2), day 14 (n = 2), and at 1 month (n = 1). They were fixed in formalin, embedded in paraffin, sectioned (2 μ), stained with histochemical dyes, immunomarked, and histologically analyzed.

Results: Histological features of acute stage MW lesion are interstitial hemorrhage, adipose, and muscular tissues' coagulation necrosis, thrombosis of myocardial interstitium small vessels at damaged and optically undamaged areas, epicardial coronary branches, and endocardial parietal thrombosis. Day 3—lymphohistiocytic infiltration (lysosyme+) highlights lesion limits. Day 7—lymphohistiocytic infiltration increases, multi‐nucleated giant cells appear surrounding/fagocyting necrotic tissue. Neovessels and scarce myofibroblasts appear. Lesion edges are now better defined. Day 14—myofibroblastic proliferation (actin++, vimentin+) creates “young” scar tissue, as in “healing by second intention.” Lesions are deeper and wider than appeared at acute stage. One month—dense fibrous tissue scar appears. Endothelial cells covering endocardium are morphologically intact. RF lesions are histologically identical to MW's, although no vessel thrombosis was identified at acute optically undamaged areas and cytomorphologic elements emerge at later stages in the healing process.

Conclusions: (1) Microwave scars are deeper and wider than the lesions observed at the acute stage. (2) Evolution of microwave lesions is faster and induces broader scars than dry radiofrequency. (3) Scar formation (both energies) is “healing by second intention.” (4) Endocardial thrombosis may occur despite morphologically intact endothelium.
Late‐Phase 3 EAD. A Unique Mechanism Contributing to Initiation of Atrial Fibrillation
Authors: BURASHNIKOV ALEXANDER , ANTZELEVITCH CHARLES
Published: March 2006

Early (EAD) and delayed (DAD) afterdepolarizations‐induced triggered activity is capable of initiating and maintaining cardiac arrhythmias. EAD‐induced triggered responses are traditionally thought to be involved in the generation of ventricular arrhythmias under long QT conditions and are precipitated by bradycardia or long pauses. In contrast, DAD‐induced triggered activity commonly underlies arrhythmias precipitated by tachycardia. Spontaneous release of calcium from the sarcoplasmic reticulum (SR) secondary to cellular calcium overload induces DADs and some forms of EADs. Recent studies from our laboratory have uncovered a novel mechanism giving rise to triggered activity, termed “late‐phase 3 EAD,” which combines properties of both EAD and DAD, but has its own unique character. Late‐phase 3 EAD‐induced triggered extrasystoles represent a new concept of arrhythmogenesis in which abbreviated repolarization permits “normal SR calcium release” to induce an EAD‐mediated closely coupled triggered response, particularly under conditions permitting intracellular calcium loading. This review briefly describes the mechanisms and properties of late‐phase 3 EADs, how they differ from conventional EADs and DADs, as well as their role in the initiation of cardiac arrhythmias, such as atrial fibrillation.
Inducible Atrioventricular Nodal Reentrant Echo Behind Organic 2:1 Infra‐Hisian Block During Sinus Rhythm
Authors: CHU CHIH‐SHENG , LEE KUN‐TAI , LAI WEN‐TER
Published: March 2006

A 77‐year‐old male patient with an intermittent 2:1 infra‐Hisian block during sinus rhythm was presented with dizziness and near‐syncope. During electrophysiological (EP) study, dual atrioventricular (AV) nodal pathways and retrograde fast pathway were easily induced by atrial and ventricular programmed stimulation, respectively. A typical slow‐fast AV nodal reentrant echo beat also could be demonstrated by single atrial extrastimulation. Atrioventricular nodal reentrant tachycardia (AVNRT) can occasionally exhibit 2:1 AV block. Conversely, AV nodal reentry property had been rarely reported behind 2:1 infra‐Hisian block. The EP presentation from this case may support the notion that tissues below the His are not part of the reentrant circuit of AVNRT.
Dissociation of the 〈001〉 Dislocations and Their Interactions with Dislocation Loops in Tetragonal BaTiO3
Authors: Cheng Shun‐Yu , Ho New‐Jin , Lu Hong‐Yang
Published: March 2006

Dislocations in pressureless‐sintered BaTiO3 ceramics have been analyzed using transmission electron microscopy. Subjected to effective sintering stresses, dislocations were generated and multiplied in plastically deformed BaTiO3 crystals by the Frank–Read mechanism from both single‐ and double‐ended sources. This is represented by dislocations encompassing a series of square‐like borders that shared a common center. All border dislocations exhibited the characteristic scallop shape. True dislocation line directions (u) were determined by trace analysis and Burgers vectors (b) by contrast analysis for the dislocations dissociated from b=〈001〉 into two half‐partials following the type (I) reaction of

by climb on {001}. Dislocation interactions between the main dislocations created from plastic deformation and dislocation loops of b=〈100〉 or 〈110〉 forming condensation of intrinsic Schottky vacancies were also found to obey the type (IV) reaction of
, the type (V) reactions of. Migrating dislocations and loops interacting mutually in several stages, illustrated schematically, before arriving at the configuration described by types (IV) and (V) were observed and discussed.
Effect of Carrier Gas Species on Ferroelectric Properties of PZT/Stainless‐Steel Fabricated by CO2 Laser‐Assisted Aerosol Deposition
Authors: Baba So , Akedo Jun , Tsukamoto Masahiro , Abe Nobuyuki
Published: March 2006

Pb(Zr,Ti)O3 (PZT) thick films were deposited onto stainless‐steel substrates by aerosol deposition using different kinds of carrier gases and were irradiated by CO2 laser both during and after deposition, for the recovery of ferroelectricity. The ferroelectric and dielectric properties of PZT films deposited using oxygen and nitrogen gases and irradiated by CO2 laser were superior to those of films deposited using He gas and irradiated by the laser. Some kinds of defects within the film were relaxed by CO2 laser irradiation during deposition, and grain growth in the film was promoted by post‐annealing using laser irradiation.
Selected‐Control Synthesis and the Phase Transition of Fe3O4 and α‐FeOOH in Ethanol/Water Media
Authors: Jia Baoping , Gao Lian
Published: March 2006

Fe3O4 nanoparticles and α‐FeOOH nanorods with tunable size have been selected control synthesized via a facile hydrothermal process in the presence of CTAB. By means of adjusting the volume ratio of ethanol/water media at three levels: 0 (in which water was used as a solvent alone), 2:3, and 4:1, phases of the products transformed from Fe3O4 into α‐FeOOH gradually. X‐ray powder diffraction, transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy were used to characterize the as‐synthesized samples. The related mechanisms of phase transformation are discussed.
Facile Synthesis of Lithium Niobate Squares by a Combustion Route
Authors: Liu Meinan , Xue Dongfeng , Luo Chao
Published: March 2006

A combustion synthesis of lithium niobate (LN) squares from activated niobium oxide (Nb2O5·nH2O) and Li2CO3 was studied to understand all the chemical reactions involved, and the nucleation and square‐growth mechanisms. It was found that first the lithium ions react with the fuel (urea), then niobium ions of Nb2O5·nH2O begin a continuous reaction with the fuel to form metal‐organic complexes. LN nuclei are formed by the solid‐state reaction of Li‐ and Nb‐organic complexes at 430°C. Lithium niobate squares are obtained in the crystallization stage at 700°C, which go on to grow into larger squares at 850°C because of the agglomeration effect.
Improvement in Biocompatibility of Fluoridated Apatite with Addition of Resorbable Glass
Authors: Lee Eun‐Jung , Chae Su‐Yeon , Kim Hyoun‐Ee , Kim Hae‐Won
Published: March 2006

The biocompatibility of fluoridated apatite (FHA) was significantly improved by the addition of a resorbable phosphate‐based glass. With the addition of small amounts of the glass (up to 5%) to the FHA, a completely densified body was obtained after sintering at 1250°C. The resultant crystalline phase was composed of tricalcium phosphate (TCP) and FHA. The addition of the glass to the FHA significantly improved the viability and functional activity of osteoblastic cells, while these were only slightly improved when the glass was added to pure hydroxyapatite, demonstrating that the fluoridation and glass addition had a synergistic stimulatory effect. This finding suggests that the glass‐added FHA bioceramic would be highly useful as a hard tissue reconstructive material.
Soil Seedbank in a Dipterocarp Rain Forest in Xishuangbanna, Southwest China1
Authors: Tang Yong , Cao Min , Fu Xianhui
Published: March 2006

Dipterocarp rain forest reaches its northern latitudinal limit in Xishuangbanna, Southwest China. We studied the soil seedbank of dipterocarp rain forest in Xishuangbanna during the dry and wet seasons. Results showed that there were large seed accumulations in both the dry (mean ± SD; 3925 ± 2533 seeds/m2) and wet seasons (5415 ± 3232 seeds/m2). One hundred and sixteen species of seed plants were identified from germination, 66 percent of which were woody species. Weed or pioneer species dominated the seedbank. The soil seedbank in Xishuangbanna had similar species composition as compared to those in tropical Asia, but higher seed storage reflects the intense disturbance and forest fragmentation in this area.
Evaluation of a Chimney Drain Design in an Earthfill Dam
Authors: Maslia Morris L. , Aral Mustafa M.
Published: March 2006

Two earthfill sections of Wallace Dam on the Oconee River near Eatonton, Georgia were constructed with vertical drainage filters (chimney drains) in a clay fill zone. In order to evaluate the performance of the filter in the west dike of Wallace Dam, the finite element Galerkin method was utilized in formulating a numerical model to study the steady‐state saturated‐unsaturated seepage characteristics through the earth dam. The resulting model is applied to Station 58+00 of the west dike of Wallace Dam. Numerical results for the four cases analyzed in this study describe the location of the zero pressure isobar and total hydraulic head values ranging from 425 feet (130 m) to 365 feet (111 m). Model results indicate a maximum seepage velocity of 2.62 feet per day (0.80 m/day) using a saturated horizontal hydraulic conductivity of 0.283 foot per day (8.64 cm/day). A maximum seepage rate is calculated to be 0.266 cubic foot per second (7.52 × 10−3 m3/sec). Analysis of the hydrostatic uplift forces along the base of the dam indicates an average pressure head reduction of 51 feet (16 m) from the upstream to the downstream side of the dam. Comparison of local seepage velocities to the critical seepage velocity upstream of the filter and inside the filter indicate a factor of safety against piping (a factor of safety against a quick condition arising in the soil) ranging from 0.3 to 3.7.
Fly Ash Disposal in a Limestone Quarry
Authors: Peffer Jeffrey R.
Published: March 2006

Approximately 740,000 tons (670,000 metric tons) of eastern bituminous coal fly ash were deposited at the abandoned Zullinger limestone quarry from 1973 to 1980. The quarry extended below the water table and was not lined to isolate the ash from the aquifer. The initial filling involved dumping ash directly into the quarry water. The quarry was situated in folded and fractured limestone with relatively high solution‐void permeability. Ground‐water quality was monitored at the site for seven years through a network of wells. During the first three years of the filling operation, high levels of sulfate were detected in down‐gradient ground water. However, this initial pollution diminished sharply in 1976 when the ash filled the volume of the quarry below the water table. Long‐term ground‐water pollution has apparently not resulted. The lack of any significant long‐term impact on ground‐water quality is attributed to the low permeability of the ash relative to the surrounding limestone aquifer. Typically alkaline limestone ground water at the site is also attributed with neutralizing the low pH fly ash which was deposited.
Type Curves for Large‐Diameter Wells Near Barriers
Authors: Şen Zekâi
Published: March 2006

The author has used the concept of depression cone volume to derive type curve equations for large‐diameter wells in aquifers of finite extent. Comparisons with the corresponding type curves in an infinitely extensive aquifer have been given. These solutions are based on joint exploitation of the ground‐water movement equation (Darcy's law) and the continuity equation for large‐diameter wells.
Representation of Multiaquifer Well Effects in Three‐Dimensional Ground‐Water Flow Simulation
Authors: Bennett Gordon D. , Kontis Angelo L. , Larson Steven P.
Published: March 2006

The presence of multiaquifer or multilayer wells changes the nature of the equations which must be solved in a three‐dimensional ground‐water flow simulation and, in effect, alters the stencil of computation. A method has been devised which takes this change into consideration by allowing simulation of the hydraulic effects of a multiaquifer well on the aquifer system. It also allows for calculation of the water level and individual aquifer discharges in such a well. The method is valid for the case of a single well located at the center of a square node block. Where more than one well per node is involved, the effects of the stencil alteration still must be considered, although difficulties arise in estimating and justifying the parameters to be utilized.
A COMPACT MODIFIED THREE‐DIMENSIONAL AQUIFER SIMULATION PROGRAM FOR SMALL COMPUTERS
Authors: Briz‐Kishore B. H. , Avadhanulu R.V.S.S.
Published: March 2006

The software for simulation of the three‐dimensional ground‐water flow, developed by Trescott (1975), is executable only on bigger machines with large memory capacities. To popularize the sophisticated software for easily accessible small machines, the organization is restructured and various programming facilities are availed. The new design is tested with an earlier quoted example. The program requires about 11K bytes of memory as against 72K bytes of the original program on IBM/370. The methodology borne out of the present work to implement large programs for small computers is presented along with the modified code.
Storage and Retrieval of Ground‐Water Data at the U.S. Geological Survey
Authors: Mercer Maria W. , Morgan Charles O.
Published: March 2006

The U.S. Geological Survey maintains a computerized ground‐water site‐inventory (GWSI) file that contains information about wells and springs at sites from all States of the United States. This file contains data collected by U.S. Geological Survey personnel and personnel of cooperating State, local, and Federal agencies. The file is easily accessible to members or users of the National Water Data Exchange. Since the establishment of the GWSI file in 1974, the data base has grown 19 percent per year and contains information on about 770,000 sites as of February 1981.
The Unreliability of Open Observation Boreholes in Unconfined Aquifer Pumping Tests
Authors: Rushton K. R. , Howard K.W.F.
Published: March 2006

Initial attempts to estimate unconfined aquifer parameters from a pumping test using an open observation borehole proved to be unsuccessful. However, when separate piezometers were installed along a vertical section, significant differences in ground‐water head were noted. These differences suggest that rather than providing an average ground‐water head, the open borehole provides a means of flow between the different elevations and therefore produces misleading results.

The results for the separate piezometers are analysed using a numerical model, and reasonable values of the aquifer parameters are deduced.
Economics of Improving Well and Pump Efficiency
Authors: Helweg Otto J.
Published: March 2006

Significant savings are frequently achieved from increasing well and pump efficiency by repair or replacement. Replacement analysis (a part of engineering economics) may be used to schedule these actions. The criterion is to maximize net benefits or minimize the cost of water. The optimal timing of repair or replacement occurs when the cost per unit of water from the old system becomes more than the minimum annualized cost per unit of water from the new system.
Prediction of Economic Potential for Irrigation Using a Ground‐Water Modela,b,c
Authors: Kent D. C. , Naney J. W. , Witz F. E.
Published: March 2006

The objective of this study is to demonstrate the application of a predictive ground‐water potentiometric‐head model to estimate the profitability of irrigation in contrast to that of dry‐land farming. Unit cost per acre‐foot of water required for a variety of crops is used to determine the distributive impact of predicted aquifer depletion at 5‐year intervals during 20 years of simulated pumping. A land‐use planning scheme is proposed for identifying areas (one square mile or less) where various crop types can be irrigated based on benefit‐cost criteria for two arbitrary pumping rates as well as on future energy and well development costs. Maps showing areas of profitable production are presented for cotton and alfalfa as examples of crops requiring as much as 1 and 2 ac‐ft/ac/yr (0.30 and 0.60 ha‐m/ha/yr), respectively. Irrigation‐water needs and related profitability are presented as examples for several crops by using the model.
Tracing Fluid Sources in the East Shore Area, Utah
Authors: Cole David R.
Published: March 2006

Stable isotope and fluid chemistry investigations in complex hydrogeologic areas have proven useful in delineating the origin of thermal waters and their interaction with local ground‐water reservoirs. The application of these techniques is illustrated using water samples collected from all hot and warm springs and many of the wells in the East Shore area, Utah. These samples were analyzed for major cations and anions, oxygen‐18/oxygen‐16 and deuterium/hydrogen ratios.

The data presented suggest the presence of at least two and perhaps three distinct hydrogeologic regimes. One regime involves fault‐controlled deep circulation of waters derived from high elevations in mountains toward the east. These waters evolved into the sodium plus potassium, chloride‐enriched hot spring fluids that are high in total dissolved salt concentration (greater than 4,000 mg/1), exhibit oxygen‐18 enrichment due to geochemical rock‐water interaction at depth and have deuterium/hydrogen ratios similar to high elevation mountain springs. A second hydrogeologic regime is comprised of waters derived from lower elevations that infiltrate into the shallow valley sediments. These dilute calcium plus magnesium, bicarbonate fluids comprise most of the area's ground‐water supply.

Leakage of thermal waters into overlying cooler aquifers is observed in the vicinity of the hot springs, and is believed to occur in several other portions of the East Shore area. These leakage zones make up the third hydrogeologic regime observed in the East Shore area.
RELATIONSHIPS BETWEEN SATURATED HYDRAULIC CONDUCTIVITY AND SOME PHYSICAL AND CHEMICAL PROPERTIES
Authors: Hendry M. J. , Paterson B. A.
Published: March 2006

Abstract Multiple regression analyses produced low R2 values of measured physical and chemical parameters and saturated hydraulic conductivities (K sat) for southern Alberta soils. We concluded that these physical and chemical parameters are inappropriate in themselves for estimating laboratory or field‐determined saturated hydraulic conductivities under southern Alberta conditions and that other factors which may exert greater control on K sat (i.e., structure) should be included in the regression analyses.
Prospect Risk Analysis Applied to Ground‐Water Reservoir Evaluation
Authors: Davis George H.
Published: March 2006

A methodology is proposed which provides predevelopment assessments of the potential yield of ground‐water reservoirs. A systematic assessment of aquifer parameters leads to estimates of ground‐water storage capacity and the geologic risks that may affect those estimates. Area of reservoir, average saturated thickness of aquifers to a limit of economic dewatering, and average specific yield, all arrived at through a Delphi procedure are combined in a Monte Carlo simulation to yield an unrisked product at several probability levels. Marginal probabilities are assigned to each parameter and combined in a further Monte Carlo simulation to yield a series of risked estimates. The results are expressed in a table and as cumulative probability curves of ground‐water storage capacity that can provide a basis for economic modeling. The method is analogous to methods widely applied in the petroleum and other extractive industries. All basic hydrogeologic data are laid out in a systematic way, permitting planners to compare reservoirs on a common basis and to judge the reliability of the estimates. Once the geologic models have been developed, they can be updated readily as additional information becomes available. The method is particularly well‐suited to preliminary assessments of the development potential of undeveloped or poorly‐explored areas, and to regional evalution where only parts of the regional have been subject to intensive ground‐water development.
Hydrogeologic Control of Localized Iron‐Enriched Ground Water, Lima, Ohio
Authors: Strausberg Sanford I.
Published: March 2006

Entrenchment and subsequent filling of a glacial valley have led to localization of iron‐enriched ground water in the Silurian carbonate aquifer at the Vistron plant, Lima, Ohio. All production wells are open exclusively to the carbonate aquifer. Water from the saturated glacial deposits of relatively low permeability and high ironcontent is drawn laterally into the more permeable carbonate aquifer containing water with relatively low concentrations of iron. Wells closest to the saturated glacial deposits yield water with iron concentrations greater than 1.4 milligrams per liter. These wells, in the southwestern part of the site, apparently form a sink preventing iron‐enriched water from migrating into other pumping wells in the central and northern parts of the area.

Iron concentrations have not increased in individual wells between 1971 and 1981. They are not expected to increase in the central and northern wells as long as about 20% of the plant's ground water is withdrawn from at least two of the southwestern wells.
Impact of Lake Michigan Allocations on the Cambrian‐Ordovician Aquifer System
Authors: Visocky Adrian P.
Published: March 2006

Overpumping of the Cambrian‐Ordovician aquifer in the Chicago area has caused severe water‐level declines in portions of Cook, DuPage, Kane, and Will Counties. Recent changes in the accounting procedure for diversion of Lake Michigan water have released more water for public supplies. As communities currently withdrawing water from deep wells receive allocations of Lake Michigan water, deep pumpage will decrease in those areas and water levels will partially recover. Major cones of depression will shift southward to Joliet and westward to the Fox River communities north of Aurora. Critically low water levels caused by pumpage in these areas will result in a loss of pumping capacity of as much as 19% by the year 2020. Despite lake allocations, deep pumpage will grow again and will still exceed the practical sustained yield (65 mgd/2.46 × 105 m3/day) of the aquifer. Continued growth in Wisconsin pumpage will also contribute an estimated additional decline of about 80 feet near the State line between 1980 and 2020.
Methods of Forecasting and Mapping of Ground‐Water Tables in the USSR
Authors: Zaltsberg E.
Published: March 2006

This is a short description of the extensive USSR experience in the field of hydrogeological forecasting in large territories. The composition of the forecast consists of these stages: collection and analysis of relevant information; choice of predicted table; calculations of the forecast equations; and extrapolating the forecast in the territory. Each of these stages is briefly discussed.
Identification of Recharge Areas Using Geochemical Factor Analysis
Authors: Lawrence Fred W. , Upchurch Sam B.
Published: March 2006

Factor analysis is useful for interpreting commonly collected ground‐water quality data and relating those data to specific hydrogeologic processes. One hundred nine ground‐water quality samples from wells completed in the upper Floridan Aquifer near Live Oak, Florida were analyzed for major dissolved constituents. R‐mode factor analysis was used to separate those chemical variables that reflect areally‐significant recharge processes from those related strictly to the dissolution of aquifer materials. Areas impacted by direct, rapid, artificial recharge through drainage wells and sinkholes, as well as by slow, natural recharge into the Floridan Aquifer, were delineated. Four factors which represent different chemical processes were identified and their relative areal impact determined. These processes are: (1) regional dissolution of the aquifer limestone, (2) dissolution and ion exchange in the discontinuous, semipermeable layer that overlies portions of the aquifer, (3) and (4) recharge from local, urban and agricultural runoff.
Sensitivity Analysis and the Ground‐Water Inverse Problem
Authors: McElwee Carl D.
Published: March 2006

In this work, an indirect inverse method utilizing sensitivity analysis is employed to help understand the reasons for model insensitivity. The results of the sensitivity analysis allow the modeler to delineate insensitive areas of the model where inverse procedures will be more subject to error. Sensitivity coefficients are defined and discussed. A differential equation is developed for the sensitivity coefficients that will generally be solved by numerical techniques. A relatively simple least squares' inverse procedure is used on a hypothetical model to illustrate typical problems that can be encountered. In particular, the effect of data accuracy is considered. The low sensitivity areas of models are generally related to small values of δh/δx and δh/δt. The fact that considerable error in the transmissivity and storativity may occur in areas of low sensitivity should not be looked upon as a failing of the inverse procedure. It is simply a fact that not all areas of the model have been stressed equally. The main advantage of the present work is that areas of low sensitivity may be delineated.
Calculation of Velocity in Three Space Dimensions from Hydraulic Head Measurements
Authors: Abriola Linda M. , Pinder George F.
Published: March 2006

This paper describes a systematic and straightforward method for the estimation of velocity components in three dimensions from hydraulic head data. Groups of four measurement points are connected to form tetrahedrons, and a linear interpolation scheme is used to obtain a head gradient estimate for each tetrahedron. Application of Darcy's law then yields the desired velocity component values. A sample calculation and comparison between this method and a two‐dimensional approach are also included.
Classification of Ground‐Water Systems of the United States
Authors: Heath Ralph C.
Published: March 2006

Classification of ground‐water systems provides a useful basis for the transfer of hydrologic knowledge from one site to another and for enhancing the public's understanding of ground water. The five features of ground‐water systems useful in classification are (1) components of the system, (2) nature of the water‐bearing openings, (3) composition of the rock matrix, (4) storage and transmission characteristics, and (5) recharge and discharge conditions. Using these features, the United States can be divided conveniently into 14 regions.
Evaluating and Improving Existing Ground‐Water Systems
Authors: Helweg Otto J.
Published: March 2006

Considerable energy savings are available from improving well and pump efficiencies. One major problem is evaluating the well and pump inefficiencies over prolonged periods of time, because these efficiencies are erratic unless normalized. A new well should be tested at different discharges to construct a relationship between specific capacity and drawdown. Future well efficiency tests should compare the specific capacity with the original curve at the test discharge. The departure from the original curve indicates the loss in well efficiency. Similarly, pump efficiency needs to be normalized, so that the tested efficiency may be compared with the original efficiency at the test discharge.
Natural Buffers for Sludge Leachate Stabilization
Authors: Makeig Kathryn S.
Published: March 2006

Large quantities of sludge can be disposed of safely by burial in narrow trenches. This paper describes a study to quantify the amount of buffer area around a trenching operation that would allow for the natural soils to stabilize sludge leachate without threatening the ground‐water supplies of surrounding communities. A vertical buffer consists of a thickness of unsaturated soil below the base of the trench. Its thickness is calculated by comparing the cation exchange capacity of the soil with the exchangeable cations in the sludge leachate. Data from metropolitan Washington, D.C. consistently require a vertical buffer of less than 3 feet thick. A minimum of 3 feet of unsaturated soil is recommended as a margin of safety, although no specific studies were performed to reach this value. The horizontal buffer is a strip of land that must be maintained between the trenching operations and the site boundary. Its width can be more than two orders of magnitude greater than the vertical buffer. Its width is based on the nitrogen loading of the soil from the sludge and the mobility of nitrate in the upper aquifer based primarily on hydraulic conductivity and the characteristics of the sludge/soil interaction. An advection‐dispersion model predicts nitrate concentrations for various buffer widths, and is used in conjunction with a specified maximum allowable nitrate concentration to determine a minimum horizontal buffer under certain ground‐water flow conditions.
Advection‐Dispersion Interpretation of Tracer Observations in an Aquifer
Authors: Hoehn Eduard , Roberts Paul V.
Published: March 2006

Data from field tracer experiments are interpreted to evaluate the adequacy of an advection‐dispersion model for simulating field conditions. A stimulus‐response approach based on chemical reactor theory was applied. Two different pulse stimuli at an injection well resulted in responses in two observation wells located at distances of 8 and 17 m, respectively, from the injection well. The wells are perforated over the entire aquifer thickness of 1–2 m. The behavior of the two conservative tracers agreed closely with each other. Breakthrough response curves revealed extended trailing edges (tailing), especially at the nearer well. A two‐domain model is employed to extend the simple advection‐dispersion equation to account for the observed tailing. Response curves of concentrations were fitted with finite‐difference simulations using the two‐domain model. The simulations using the two‐domain model agreed well with the field observations. The responses at the more distant well were characterized by values of dispersivity equal to or slightly smaller than those at the nearer well.
Statistical Identification of Hydraulic Connections Between the Surface of a Mountain and Internal Mineralized Sources
Authors: Williams Roy E.
Published: March 2006

Mount Emmons is located near Crested Butte, Colorado. It is the site of a proposed molybdenum mine that would extract ore from within the core of the 12,000‐foot plus peak. AMAX Inc. is proposing to extract the ore body by utilizing a block caving technique that requires a thorough understanding of the hydrology of the mountain.

This study was conducted to test the hypothesis that water quality data from various sources can be clustered and grouped into distinct populations that can be correlated with hydrogeologic features mapped on the mountain. Cluster analysis and canonical analysis are applied to mine water quality data, drillhole water quality data, spring‐water quality data and surface‐water quality data. Identified subpopulations indicate the presence or absence of mineralized sources in recharge areas, along flow paths or in discharge areas for the different water quality groups. The statistical analyses in combination with fault‐vein mapping and debris slide mapping facilitate identification of preferential hydraulic connections between the surface of Mount Emmons and internal mineralized zones. The majority of the springs on Mount Emmons were shown to be derived from debris slides. These springs discharge water that meets drinking‐water standards. The statistical analyses in combination with the hydrogeologic mapping indicate that these springs should not be affected significantly by mining. The analyses and hydrogeologic mapping also delineate those ground‐water discharge areas that can be expected to be affected by mining. The delineation of the latter zones is essential to the mining plan; preventative and corrective measures can be implemented in the identified areas in order to assure that negative impacts of mining are avoided.
BOREHOLE COLLECTOR FOR IN‐SITU CHEMICAL ANALYSIS OF GROUND WATERa
Authors: Harrar Jackson E. , Raber Ellen
Published: March 2006

Abstract. An apparatus has been designed for collection of ground‐water samples in locations of limited water flow when atmospheric contamination must be avoided. The system consists of a packer outfitted with valves, a flow cell, and probes for measurement of dissolved oxygen, pH, and Eh, and is designed for installation in a 3‐inch (7.6‐cm) diameter borehole. The oxygen probe, which is a commercially available electrochemical device, functions accurately without water flow or oxygen consumption. The borehole collector system has been used to characterize the ground water in the Climax granite stock at the Nevada Test Site of the U.S. Department of Energy.
CULTURE METHODS FOR THE ENUMERATION OF IRON BACTERIA FROM WATER WELL SAMPLES – A CRITICAL LITERATURE REVIEW
Authors: Smith Stuart
Published: March 2006

Abstract. “Iron bacteria” which are known to occur in water wells are briefly described, along with a history and description of their economic significance. The main concerns of this monograph are the laboratory and culture methods described by the various authors and those currently in practice. A bibliography of the limited valuable literature is provided and commented upon.

Species of concern are Gallionella ferruginea and those species of the Leptothrix Sphaerotilus group. Emphasis is on the rapid and reliable identification of these organisms.
A Numerical Model Study of Ground‐Water Contamination from Price's Landfill, New Jersey— I. Data Base and Flow Simulation
Authors: Gray William G. , Hoffman Jeffrey L.
Published: March 2006

Toxic waste contamination is currently threatening the Atlantic City, New Jersey public water‐supply wells. The geohydrologic data for this region are presented and organized into a format suitable for a numerical model study of the contamination problem. Presentation of the data in light of numerical work reveals the importance of good estimates of boundary conditions, historical pumping records, reliable water‐quality data, accurate well logs, and reasonable parameter estimates. One set of measured head data is simulated.
A Numerical Model Study of Ground‐Water Contamination from Price's Landfill, New Jersey — II. Sensitivity Analysis and Contaminant Plume Simulation
Authors: Gray William G. , Hoffman Jeffrey L.
Published: March 2006

A numerical model of flow and transport in the vicinity of Price's Landfill and the Atlantic City public water‐supply wells is used to estimate the extent of the existing contamination problem. Model parameters such as boundary conditions, pumping rates, permeability, and dispersivity are varied to demonstrate the sensitivity of the model to these quantities. A historical simulation of the past ten years of contamination is obtained and two schemes for remediation of the contamination problem are compared. In the light of this work, additional data requirements are revealed.
Field Determination of Aquifer Thermal Energy Storage Parametersa
Authors: Parr A. David , Molz Fred J. , Melville Joel G.
Published: March 2006

Determination of the potential of a specific confined aquifer as an effective thermal energy storage medium requires thorough knowledge of the geochemical, thermodynamic, and hydraulic properties of the aquifer and its confining layers. A series of laboratory and field studies must be performed in order to determine the fundamental parameters. Procedures and analyses of a series of tests for a confined aquifer near Mobile, Alabama were completed prior to an aquifer thermal energy storage experiment. Parameters determined were: the regional gradient; vertical and horizontal permeabilities of the storage aquifer; horizontal dispersivity of the storage aquifer; vertical permeability of the confining layers; and thermal conductivities, heat capacities, and chemical characteristics of the aquifer matrix and native ground water.
Application of Resistivity Surveys to Regional Hydrogeologic Reconnaissance
Authors: Stewart Mark , Layton Michael , Lizanec Theodore
Published: March 2006

Vertical electrical soundings using DC resistivity methods have been completed along over 60 miles of survey lines in southwest Florida. The resistivity soundings were obtained in order to outline major hydrogeologic features as part of a regional hydrogeologic investigation covering approximately 400 square miles. The two significant hydrogeologic features which can be effectively mapped on a regional scale by DC methods are the presence of shallow, high resistivity limestones associated with late Tertiary reef complexes, and the approximate depth to waters with TDS concentrations well above the potable water limits. The reef limestones commonly exhibit very high transmissivities and are potential sites for ground‐water development. The approximate thickness of potable waters allows resource investigations to be limited to the most promising areas and a rough assessment of the total resource to be made for long‐term planning. The interpretation and mapping of the resistivity section is accomplished through published resistivity inversion and computer graphics programs. This automated data processing produces resistivity maps and sections without requiring extensive geophysical training of the interpreter. The automatic interpretations compare well with more traditional master curve interpretation procedures, and have the same limitations with equivalence of solutions and geologic correlation, but are produced with considerably less effort.
The Rainfall/Water‐Table Level Relationship of an Unconfined Aquifer
Authors: Viswanathan M. N.
Published: March 2006

The soil parameters that determine the infiltration rates of a shallow unconfined coastal aquifer due to rainfall were obtained using the recursive least squares method. The parameters were predicted by minimizing the mean square error between the estimated and measured water‐table levels in a bore hole. The parameters λt, a drainage factor, βt, a parameter which accounts for external disturbances, and αt, a set of parameters which determine the infiltration rates due to rainfall, were all treated as time‐dependent variables. Their variation is traced by introducing a “forgetting factor” in the algorithm used to determine the parameters. The parameters were determined using rainfall and water‐table levels for the year 1979 at a bore hole. The parameters βt and αt varied considerably over the period of time and λt remained constant. From the parameters obtained, it appears that most of the recharge due to rainfall takes place within the first two days of the event. After two days there is very little variation in the water‐table level due to rainfall although there is a slight drop on the third, fourth and fifth day, presumably due to the escape of entrapped air beneath the water‐table level.
THE APPLICATION OF A MICROCOMPUTER IN THE ANALYSIS OF PUMPING TEST DATA IN CONFINED AQUIFERS
Authors: Dumble Peter , Cullen Kevin T.
Published: March 2006

With an Apple II microcomputer it is possible to rapidly generate and graphically compare theoretical time‐drawdown curves with field data from pumping tests in confined aquifers. This technique has the advantage over standard curve‐matching methods in that any solution can be tested over the complete range of field data.
AQUIFER MODELING WITH A HANDHELD CALCULATOR — AQMODL
Authors: Rayner Frank A.
Published: March 2006

AQMODL is an analytical mathematical aquifer modeling program for the HP‐41C handheld programmable calculator. It does not require any written instructions for its use. It guides the operator through its use and prevents operator error. It is designed so that it can be used by anyone only basically familiar with the operation of the HP‐41C calculator, and with aquifer modeling.

There are no special key assignments, and no special data preparation or storage operations or any other prior preparation necessary before running AQMODL, simply XEQ AQMODL and follow the calculator’guidance.

AQMODL can be used to model simple or complex single aquifer situations. It considers any regional change (rising or falling) in water level not necessarily associated with the development being modeled. It also models the aquifer's water‐level gradient.

Sixty pumping and/or recharge wells can be entered into the model, and the resultant change in water level and water‐level elevation determined at an unlimited number of observation points in the aquifer.
GROUND‐WATER MODELING WITH AN INTERACTIVE COMPUTER
Authors: Bloomsburg G. L. , Rinker R. E.
Published: March 2006

. A large finite element program has been adapted to a PDP‐11/23 minicomputer to obtain the advantages of an interactive computer system. The program used is UNSAT2, a code for unsteady, saturated and/or unsaturated flow of ground water. The advantages and disadvantages of this type of system in terms of the potential for its use in mine hydrology and related areas are considered. Some of the advantages of this interactive system are: (1) ease of data input by the use of a digitizer; (2) the opportunity to review all output files and to select for printing only those of interest; and (3) the opportunity to change the physical boundaries of a problem at any desired time to make use of new information as a project progresses. This feature is particularly useful in mine‐related water inflow predictions. This characteristic facilitates the simulation of flow into a vertical mine shaft as the shaft is being developed. A problem presented to demonstrate this feature illustrates some of the above advantages. The major disadvantage is increased computational time. However, the authors believe that this disadvantage may not be particularly great because many organizations are not required to cost‐account time on a minicomputer whereas this may not be the case for large machines.
HP41C AND TI59 PROGRAMS FOR ANISOTROPIC CONFINED AQUIFERS
Authors: Parr A. David , Melville Joel G. , Molz Fred J.
Published: March 2006

. Programs are presented for the HP41C and TI59 programmable calculators for determining the ratio of horizontal to vertical hydraulic conductivity in anisotropic confined aquifers from pumping test data or for calculating drawdown given the aquifer parameters. The programs, based on Hantush's drawdown equations (1961), eliminate the need to perform triple interpolation in obtaining the drawdown correction factor given in tabular form by Weeks (1969). The programs are illustrated by example.