bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dental attitudes: proximal basis for oral health disparities in adults
Authors: Riley Joseph L. , Gilbert Gregg H. , Heft Marc W. 
Published: July 2006

Abstract –  Objectives:  Behavioral science postulates that underlying characteristics of populations, rather than sociodemographic groupings, are more proximal causes of oral health disparities through differing oral health behaviors. To our knowledge this is the first report in the literature that examines longitudinal correlates of oral health and dental care using groups of persons holding similar attitudes and beliefs.Methods:  The subjects were 873 participants in the Florida Dental Care Study, a longitudinal study of oral health among dentate adults. Hierarchical cluster analysis identified four groups with similar dental attitudes that were labeled ‘favorable attitudes about dental care’, ‘frustrated believers in dental care’, ‘negative attitudes and cost concerns’, ‘pessimistic about personal and professional oral care’.Results:  The attitudinal groups cut across race, sex, and age with race and educational status the best discriminators among sociodemographic and economic variables. The negative attitude group reported the least preventive care and the largest oral health decrements on clinical examination at baseline and 24 months. The group with favorable attitudes about dental care reported the highest number of preventive and restorative visits and the lowest point‐prevalence of toothache pain, temperature sensitivity, and painful gums. The frustrated believers have access to dental care equivalent to the favorable attitude group, but may delay seeking dental care until oral disease becomes more severe, based on their pattern of preventive, restorative, and dental extraction visits. Additional group differences on oral health and dental care are reported.Conclusion:  This study takes a novel approach to examining oral healthy disparities. Differences in oral health behaviors support the validity of the groups.
Periodontal and oral microbiological status of an adult population undergoing haemodialysis: a cross‐sectional study
Authors: Castillo A , Mesa F , Liébana J , García‐Martinez O , Ruiz S , García‐Valdecasas J , O'Valle F 
Published: July 2006

Objectives:  The aim of this cross‐sectional study was to evaluate the periodontal status and oral microbiological patterns of a population with end‐stage renal disease (ESRD), undergoing haemodialysis (HD).Design:  This was a cross‐sectional study, involving 52 patients from the Nephrology Department and 52 matched control subjects.Materials and methods:  The subjects had a periodontal clinical examination; subgingival plaque samples were taken and analysed using a semiquantitative polymerase chain reaction (PCR) test to detect Porphyromas gingivalis, Tannerella forsythia, Prevotella intermedia, Prevotella nigrescens and Actinobacillus actinomycetemcomitans. Subgingival plaque and saliva samples were studied for Candida and Enterobacteriaceae.Main outcome measures:  Most of the 104 subjects had some degree of loss of periodontal attachment (LPA) ≥3 mm [11 (10.5%) had severe LPA; 16 (15.4%) moderate LPA; and 64 (61.5%) mild LPA]. Only 13 subjects (12.5%) presented good periodontal health.Results:  No statistically significant differences were found between the HD patients and the control group regarding bleeding index, number of teeth, or percentage of LPA ≥3 mm. However, a statistically significant difference was seen in the degree of oral hygiene.Conclusions:  On the basis of the findings presented here, we cannot associate ESRD with more severe periodontal destruction. Although HD patients presented a higher number of periodontopathic microorganisms than the matched controls, a prolonged duration of HD did not bear a statistically significant relationship with the percentage of sites with LPA ≥3 mm, specific microbiota or composition of biofilm.
Bore Hole Sampling of Saturated Uncemented Sands and Gravels
Authors: Barton C. M. 
Published: July 2006

ABSTRACTBore hole sampling of loose saturated sands and gravels forms a very important part of water well investigations. The materials are often difficult to sample and the adoption of adequate equipment and techniques can sorely tax the ingenuity of the driller.In some situations, the standard exploration sampling procedures can provide satisfactory information, while in others, it is necessary to resort to more precise techniques.A great variety of samplers have been designed including types such as open drive, piston drive, jet and extension flap samplers. No single sampler can cover the very wide range of material conditions and operational requirements which may be met during the drilling of water wells.In extreme circumstances, particularly for uncemented or poorly cemented gravels, it may be found necessary to stabilize the strata prior to sampling.
Sampling of Variable, Waste‐Migration Patterns in Ground Watera
Authors: Childs K. E. , Upchurch S. B. , Ellis B. 
Published: July 2006

ABSTRACTA survey of waste‐migration patterns from septic‐tank/ tile‐field systems surrounding Houghton Lake, Michigan indicates that sampling plans designed to detect and quantify waste migration in ground water should be predicated on the concept that the waste plume may be complex and that the plume may not follow regional, ground‐water flow. The waste‐migration plumes at Houghton Lake range from simple, multichemical plumes that move with regional flow to complex plumes that bifurcate, that show different migration patterns for different chemicals, and that move up the regional gradient for short distances. The complexity of these patterns is attributed to a combination of the following system properties: loading rate and recharge at the waste source, local hydrology, chemical‐adsorption capacity of the soil, soil microbiology, regolith texture and fabric, and proximity to other waste sources. Based on the observed patterns, it is suggested that observation wells be placed so that an in‐depth, 3‐dimensional array of samples can be obtained. The wells should be of sufficient depth to insure that deep‐moving plumes can be detected and, if the actual, vertical‐migration pattern is of importance, the wells should allow collection of water samples at a number of depths. The waste‐migration pattern should be monitored throughout the year in anticipation of vertical movement of the plume axis during periods of surface recharge. If more than one chemical is of interest, then it is unsafe to assume that an index chemical, such as chlorides, demonstrates the migration of the other chemicals and analyses must be run for the other chemicals.
Chemical Interaction During Deep Well Recharge, Bay Park, New Yorka
Authors: Ragone Stephen E. , Vecchioli John 
Published: July 2006

ABSTRACTThe U.S. Geological Survey, in cooperation with the Nassau County Department of Public Works, recharged tertiary‐treated sewage (reclaimed water) into the Magothy aquifer in 13 recharge experiments between 1968 and 1973. The recharge resulted in a degradation in water quality with respect to iron concentration and pH. Iron concentration increased from the range 0.14 to 0.30 milligrams per litre to as much as 3 milligrams per litre at the 20‐, 100‐, and 200‐foot or 6.1‐, 30‐, and 61‐metre observation wells as the reclaimed water displaced native water. The increase was presumably a result of pyrite dissolution. The pH of the water decreased from the range 5.22 to 5.72 to a low of about 4.50, predominantly as a result of cation‐exchange reactions.
Hydrochemistry and Ground‐Water Mixing in Part of the Lincolnshire Limestone Aquifer, England
Authors: Lawrence Adrian R. , Lloyd John W. , Marsh J. Marcus 
Published: July 2006

ABSTRACTA hydrochemical study is outlined which demonstrates the mixing of two different ground‐water types in the Lincolnshire Limestone aquifer. The two water types consist of a modern recharge water and an ancient possibly connate water. The hydrochemistry of the “interface zone” between the two waters is discussed in detail. In the younger water a relationship between sulphate reduction and bicarbonate is illustrated approaching the “interface zone” and is considered to be related indirectly to the mixing. Carbon isotope content is shown to be radically different in the various ground waters and supports the mixing hypothesis.
Underground Storage of Treated Water: A Field Test
Authors: Smith Charles G. , Hanor Jeffrey S. 
Published: July 2006

ABSTRACTSuccessful underground storage of large volumes of treated water (sufficient for a period of weeks or months) could provide a temporary, alternative water supply in areas where potable ground water is not available and where surface runoff varies unpredictably in quantity and quality. A small‐scale field test of underground storage, using an injection well, was performed in Jefferson Parish, Louisiana. Storage in the tested aquifer was proven to be impractical due to the pre‐existing ground‐water movement rate of 0.5 ft (15 cm) per day. A mathematical model of the injection‐storage‐production process accurately predicted the recovery efficiencies observed in the two tests. The quantity of injected water was not adversely affected by geochemical reactions occurring during the tests. The injected water was softened during storage by ion‐exchange reactions between injected water and clay particles in the aquifer.
Geoelectric Sounding for Estimating Aquifer Hydraulic Conductivity
Authors: Kelly William E. 
Published: July 2006

ABSTRACTThe objective of this study was to develop surface electrical resistivity methods for estimating hydraulic conductivities in glacial outwash materials. Aquifer electrical resistivities were determined from the results of Schlumberger electrical soundings at six sites in southern Rhode Island where pumping tests had previously been made. Hydraulic conductivities and transmissivities determined from pumping tests were then correlated with resistivities obtained from electrical soundings. Results indicate that electrical resistivities determined from soundings can be used to predict aquifer hydraulic conductivities; an empirical relation between aquifer electrical resistivity and aquifer hydraulic conductivity was developed. A semiempirical relation between aquifer formation factor and hydraulic conductivity was also developed.
Spatial and Temporal Hydrochemical Variations in a Semiconfined Buried Channel Aquifer: Esterhazy, Saskatchewan, Canada
Authors: Davison C. C. , Vonhof J. A. 
Published: July 2006

ABSTRACTGround‐water samples from a portion of a semi‐confined buried glacial channel aquifer in southeastern Saskatchewan, Canada, were collected and analyzed to determine the spatial and temporal variations of the major chemical constituents, pH, Eh and Fe. Dilute Ca‐HCO3 type water characterized the shallow portion of the aquifer. There was a linear modified Piper Plot trend toward more concentrated Na‐SO4 type water with increasing depth in the aquifer and with increased distance along the ground‐water flow path. Ground water flowing from a well penetrating the shallow portion of the aquifer responded chemically to an intense spring storm event. The ground‐water chemistry of a flowing well completed in the deep portion of the aquifer did not respond to this intense spring storm, but showed a temporal chemical trend which paralleled a midsummer recharge event. The spatial and temporal hydrogeochemical variations indicate that two chemically distinct ground‐water components, resulting from two different physico‐chemical ground‐water flow origins, are probably recharging and mixing within this portion of the buried channel aquifer.
Ground‐Water Modeling: An Overviewa
Authors: Mercer James W. , Faust Charles R. 
Published: July 2006

ABSTRACTGround‐water modeling is a tool that can help analyze many ground‐water problems. Models are useful for reconnaissance studies preceding field investigations, for interpretive studies following the field program, and for predictive studies to estimate future field behavior. In addition to these applications, models are useful for studying various types of flow behavior by examining hypothetical aquifer problems. Before attempting such studies, however, one must be familiar with ground‐water modeling concepts, model usage, and modeling limitations.
Influence of Regolith Properties on Migration of Septic Tank Effluent
Authors: Rea Raymond A. , Upchurch Sam B. 
Published: July 2006

ABSTRACTAn investigation of waste‐migration patterns from a septic system indicates that complex patterns result from minor variations in regolith adsorptive capacity and texture, local hydrology, and possibly soil microbiology. The existence of multichemical, bifurcating plumes suggest that monitor wells arranged up and downgradient and capable of multilevel sampling are essential to adequately delineate contaminant migration in ground water. The data also indicate that sampling for a single constituent could yield misleading information about the nature and distribution of other ground‐water contaminants. The ability for chemical removal by the regolith is in direct response to minor variations in silt‐ and clay‐sized particle content and corresponds to Langmuir adsorption isotherms. Silt‐ and clay‐sized particles are dominantly organic in origin. Minor iron and aluminum hydroxyoxides and clays are present.Substrate samples, when collected at regular intervals and analyzed for adsorbed constituents and textural variability, provide an integrated picture of the distribution of waste chemicals through time. Such samples also provide insight into the mechanics of plume configuration and flow characteristics within the regolith. The study shows that regolith adsorption data are essential to the determination of life expectancy of the regolith as a contaminant treatment system.
Ground‐Water Geochemistry: Arsenic in Landfills
Authors: Hounslow Arthur W. 
Published: July 2006

ABSTRACTThree key hydrogeochemical environments based on the oxidation‐reduction state of ground water are defined by the presence or absence of dissolved oxygen and hydrogen sulfide. The mobility of arsenic is greatly influenced by these dissolved gases and the behavior of iron in these same environments.The main forms of arsenic in aqueous environments are arsenate and arsenite. Arsenate occurs in oxygenated waters but if colloidal ferric hydroxide is also present, the arsenate may be adsorbed and removed from solution. In strongly reducing waters containing hydrogen sulfide arsenic is removed from solution and precipitated either as arsenic sulfide, heavy‐metal sulfarsenite compounds, or coprecipitated with iron sulfides. In mildly reducing waters lacking both dissolved oxygen and hydrogen sulfide arsenic occurs as the arsenite ion. In waters of this type the mobility of both arsenic (as arsenite) and iron (as ferrous iron) are at a maximum. It must also be stressed that arsenite is 60 times more toxic to humans than arsenate.
Bottled Waters — Expensive Ground Water
Authors: Studlick Joseph R. J. , Bain Richard C. 
Published: July 2006

ABSTRACTDue to the growing demand for bottled mineral waters, a study was undertaken to determine the quality of fourteen different brands of still and sparkling bottled waters. Objective testing showed a wide variance in taste as waters have different tastes and individual preferences are the rule. By analytical means, the mineral content of most of the tested waters met U.S.E.P.A. standards; however, some samples had unacceptable levels of sulfate, hardness, and other constituents. Cost comparisons show a wide variation in price, with all the tested waters many times more than normally available tap waters.
Sampling Ground Water for Organic Contaminants
Authors: Pettyjohn Wayne A. , Dunlap W. J. , Cosby Roger , Keeley Jack W. 
Published: July 2006

ABSTRACTThe proper collection of ground‐water samples for analysis of organic compounds differs substantially from routine inorganic constituents because the former are easily contaminated and generally appear in the parts per billion range.Much of the sampling equipment that has been developed at the Robert S. Kerr Environmental Research Laboratory during the past few years is constructed from Teflon or glass. While the former is expensive and the latter is fragile, neither contaminate or modify a water sample as does rubber, metal and most plastics.Designs are provided for a grab sampler, a continuous sampler consisting of adsorbent columns, a protective housing for a sampling system, a continuous discharge/high lift glass pump, and a system for obtaining highly volatile organic compounds from the unsaturated zone.
Velocity Calculation from Randomly Located Hydraulic Heads
Authors: Pinder George F. , Celia Michael , Gray William G. 
Published: July 2006

ABSTRACTThis paper presents a systematic method for approximating hydraulic head gradients from randomly located hydraulic head values. The locations of these head values are connected by straight lines to form a network of triangles. Over each triangle, a plane surface is used to approximate the head values; the gradient of this plane is then taken as the hydraulic gradient. Given values of porosity and hydraulic conductivity, the fluid velocity can be calculated from Darcy's Law.
Fundamental Concepts of Well Design
Authors: Williams E. B. 
Published: July 2006

ABSTRACTWell performance and production life can be enhanced greatly by proper design and operation. Using screen entrance velocity as the only design criteria is not sufficient for describing flow around the well, and in many cases leads to an overly optimistic design. Approach velocity and turbulence (Reynolds Number) are more direct concepts in regard to the factors influencing long‐term well efficiency, and their use as design criteria is strongly encouraged. In addition, sizing of screen slots and filter materials is haphazardly practiced by too many in the ground‐water industry, and requires a renewed awareness.Distribution of flow along the screen, as well as the vast number of aquifer conditions, are also factors to be considered during design. It is here that the judgement and practical experience of the hydrogeologist are most important.The fundamental design criteria are relatively simple to apply, and for the practicing hydrogeologist, the design process is aided by composite graphs. Several such design graphs are given for convenient reference.
Determination of Aquifer Parameters from Large‐Diameter Dug Well Pumping Tests
Authors: Herbert R. , Kitching R. 
Published: July 2006

ABSTRACTLarge‐diameter dug wells are the main source of water supply in many areas of the world. They are particularly useful in shallow aquifers with a low transmissivity. Existing methods for determining the transmissivity of aquifers from pumping tests carried out in dug wells were found wanting. This paper describes two new methods that can be used to determine the transmissivity of the aquifer from dug well tests. Examples of the application of the methods are given.
Simulation of the Transport of Ion‐Exchanging Solutes Using Laboratory‐Determined Chemical Parameter Values
Authors: Valocchi Albert J. , Roberts Paul V. , Parks George A. , Street Robert L. 
Published: July 2006

ABSTRACTThe practical application of simulation models of the movement of chemically reacting contaminants requires the evaluation of several chemical parameters in addition to those basic hydrogeologic and hydrodynamic parameters required to model conservative constituents. This paper deals with the use of laboratory‐determined chemical parameter values in the simulation of the transport of ion‐exchanging solutes governed by local chemical equilibrium. The transport model has been applied to a field operation involving the injection of advanced‐treated municipal waste water into an alluvial aquifer in the Palo Alto (California) Baylands region.Basic hydrogeologic parameters, such as porosity, bulk density, and aquifer thickness, were determined by analysis of observation well logs and core samples. Data on the breakthrough of a conservative tracer at various observation wells were utilized to determine an approximate velocity field and the dispersivity values. The chemical parameters (selectivity coefficients and cation‐exchange capacity) were determined using standard batch experiments conducted in the laboratory using aquifer core material. With these parameter values, the model was run to predict the breakthrough of major cations at the observation wells. The predicted results agree very closely with the actual field data. This agreement suggests that laboratory‐determined chemical parameters can be successfully used in field‐scale transport simulations.
Use of Laccase as a Novel, Versatile Reporter System in Filamentous Fungi
Authors: Mander Gerd J. , Wang Huaming , Bodie Elizabeth , Wagner Jens , Vienken Kay , Vinuesa Claudia , Foster Caroline , Leeder Abigail C. , Allen Gethin , Hamill Valerie , Janssen Giselle G. , Dunn-Coleman Nigel , Karos Marvin , Lemaire Hans Georg , Subkowski Thomas , Bollschweiler Claus , Turner Geoffrey , Nüsslein Bernhard , Fischer Reinhard 
Published: July 2006

ABSTRACT

Laccases are copper-containing enzymes which oxidize phenolic substrates and transfer the electrons to oxygen. Many filamentous fungi contain several laccase-encoding genes, but their biological roles are mostly not well understood. The main interest in laccases in biotechnology is their potential to be used to detoxify phenolic substances. We report here on a novel application of laccases as a reporter system in fungi. We purified a laccase enzyme from the ligno-cellulolytic ascomycete
Stachybotrys chartarum
. It oxidized the artificial substrate 2,2′-azino-di-(3-ethylbenzthiazolinsulfonate) (ABTS). The corresponding gene was isolated and expressed in
Aspergillus nidulans
,
Aspergillus niger
, and
Trichoderma reesei.
Heterologously expressed laccase activity was monitored in colorimetric enzyme assays and on agar plates with ABTS as a substrate. The use of laccase as a reporter was shown in a genetic screen for the isolation of improved
T. reesei
cellulase production strains. In addition to the laccase from
S. charatarum
, we tested the application of three laccases from
A. nidulans
(LccB, LccC, and LccD) as reporters. Whereas LccC oxidized ABTS (

K
m

= 0.3 mM), LccD did not react with ABTS but with DMA/ADBP (3,5-dimethylaniline/4-amino-2,6-dibromophenol). LccB reacted with DMA/ADBP and showed weak activity with ABTS. The different catalytic properties of LccC and LccD allow simultaneous use of these two laccases as reporters in one fungal strain.