bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
Soil Seedbank in a Dipterocarp Rain Forest in Xishuangbanna, Southwest China1
Authors: Tang Yong , Cao Min , Fu Xianhui 
Published: March 2006

ABSTRACTDipterocarp 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

AbstractTwo 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

AbstractApproximately 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

AbstractThe 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

ABSTRACTThe 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

AbstractThe 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

ABSTRACTThe 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

ABSTRACTInitial 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

ABSTRACTSignificant 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

ABSTRACTThe 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

ABSTRACTStable 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.
Prospect Risk Analysis Applied to Ground‐Water Reservoir Evaluation
Authors: Davis George H. 
Published: March 2006

ABSTRACTA 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

ABSTRACTEntrenchment 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

ABSTRACTOverpumping 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

ABSTRACTThis 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

ABSTRACTFactor 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

ABSTRACTIn 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

ABSTRACTThis 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

ABSTRACTClassification 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

ABSTRACTConsiderable 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.