bluuebunny/crossref_metadata_2025 huggingface dataset:
Property Tax Assessment Rates and Residential Abandonment
Authors: Arsen David
Published: July 2006

Abstract Netghbothood abandonment rates is New York City are predieted Within a model which investigates the imporatnce of property tax assessments building conditions adn tenant characteristies in owners’abandonment decision The results indicate that tax assessment rate are a mojor determinant of abon donment, and point to policy changes capable of showing the spread of aban donment in vulnerble netghbot hoods
On The “Stickiness’ Of The Economic Equilibrium Paradigm
Authors: Fischer Charles C.
Published: July 2006

Abstract. Thomas S. Kuhn, Imre Lakatos and Mark A. Zupan have made important contributions to our understanding of why paradigms of thought tend to be quite resistant to displacement, or even revision. Their work is extended in an attempt to explain the staying power of the economic equilibrium paradigm. It is argued that this paradigm is particularly “sticky” due to its pedagogical, methodological and protective properties. The implications of this for paradigm assessment and evolution are discussed.
Labor Market Underpinnings of a Caste Economy
Authors: Scoville James G
Published: July 2006

Abstract. Previous modellings by Akerlof and Scoville of a caste based economy, exemplified historically by India—in which occupations are hereditary, compulsory, and endogamous—are reviewed and contrasted, Coase/North arguments are advanced about the possible bases for labor market segmentation which would render such a caste‐type system immune to erosion by labor market competition. Historical and contemporary evidence is presented to support these arguments.
Native American Economic Development on Selected Reservations
Authors: Vinje David L.
Published: July 2006

Abstract. Native American Gaming currently is perceived as the economic development stategy that will help reduce Indian Reservations‘high rates of family poverty. There is, however, considerable legislative activity at the state and federal level which is aimed at reducing this opportunity. The paper examines three decades of economic development activity on the reservations in an attempt to explore what alternative stategies tribal governments have available in the event that Indian gambling falls short in its objective. Using Census data, the paper concludes that strategies based on the promotion of government or private employment; the promotion of natural resources or manufacturing have fallen short. Education, as an indirect approach to economic development, appears to consistently be one of the more important priorities that tribal leaders can stress in their attempts to reduce family poverty rates.
Gender Differences in the Effect of Education on the Slope of Experience‐Earnings Profiles
Authors: Duncan Kevin C.
Published: July 2006

Abstract. TWO earnings models are estimated for men and women of the National Longitudinal Survey of Labor Market Experience of Youth (1979 to 1988). Model 1 (a standard human capital equation) indicates women receive a relatively higher earnings effect from another year of education and week of work, suggesting that narrowing of the wage gap can occur through increasing these. However, increases in female education of over 20%, or increases in weeks worked of over 100% are needed to bring female earnings to the level of white males. Model 2, which includes the interaction between education and work experience, shows that more educated men have steeper experience‐earnings profiles while more educated women do not. This finding indicates different earnings growth patterns among similarly skilled and market attached men and women. Results imply that increasing female skills and work effort alone are insufficient in obtaining more equitable market outcomes and that the continuation of affirmative action policies are needed to achieve this goal.
Psychosis or temporal lobotomy: SPECT findings in a paraplegic patient with chronic mental illness
Authors: Sheehan W. , Thurber S.
Published: July 2006

Objective:  To ascertain if single proton emission computerized tomography (SPECT) imaging involving a patient with a history of head trauma, paraplegia, and chronic mental illness, would provide useful information regarding diagnosis and treatment.

Method:  A case report.

Results:  SPECT data indicated a convexity of the temporal lobe; it was significantly crumpled inward in the location of the traumatic blow suffered 18 years earlier. The center of hypoperfusion suggested a complete disruption of connections between the temporal lobe and Broca's area, and a practically ablated left temporal area.

Conclusion:  The patient was reclassified with an organic psychosis and as an individual who might benefit more from medications to treat temporal lobe irritability rather than antipsychotic medications. Despite these findings and recommendations, psychiatric personnel discharged the patient without implementation. He is currently in critical condition following a suicide attempt.
Neural response to sandblasted/acid‐etched, TiO2‐blasted, polished, and mechanochemically polished/nanostructured titanium implant surfaces
Authors: Onur Mehmet A. , Sezgin Aysun , Gürpιnar Aylin , Sommer Andrei , Akça Kιvanç , Çehreli Murat
Published: July 2006

Abstract: The purpose of this study was to explore morphologic, functional, and behavioral effects of rough (sandblasted‐large grid/acid‐etched (SLA) and TiO2 blasted), mechanically polished, and mechanochemically polished titanium implant surfaces on nerves. The compound action potentials (cAPs) of sciatic nerves of sacrificed Wistar rats (n=10) were quantified at the in vitro level, while contacting disk‐shaped test specimens. The test specimens were also implanted directly on the sciatic nerves of another group of animals (n=33), hot‐plate tests were undertaken for 10 consecutive days, and then the animals were sacrificed. Quantification of signal transduction speeds and cAPs of the nerves of these animals were undertaken at the in vitro level. Finally, the nerves were processed for histologic analysis. The signal transduction speeds and duration of cAPs of all groups were similar (P>0.05), whereas the amplitudes of cAPs of nerves contacting SLA implants were higher than those of TiO2 blasted and mechanochemically polished surfaces (P<0.05). Response latencies of nerves contacting mechanically polished specimens were slightly higher than the other groups (P>0.05). Histologic evaluations did not reveal any signs of adverse tissue response adjacent to specimens tested. Rough and polished titanium implant surfaces lead to similar neural response in vivo and in vitro that fall into physiologic limits.
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.
In vivo protective effect of melatonin on cadmium‐induced changes in redox balance and gene expression in rat hypothalamus and anterior pituitary
Authors: Poliandri Ariel H. B. , Esquifino Ana I. , Cano Pilar , Jiménez Vanessa , Lafuente Anunciación , Cardinali Daniel P. , Duvilanski Beatriz H.
Published: July 2006

Abstract:  Cadmium (Cd) is widely used in industrial applications and is an important side contaminant of agricultural products. As an endocrine disruptor, Cd modifies pituitary hormone release. It has been shown that this metal causes oxidative stress in primary cultures of anterior pituitary cells. To examine whether Cd induces redox damage in the hypothalamic–pituitary axis in vivo and to evaluate the efficacy of the antioxidant molecule melatonin to prevent Cd activity, rats were exposed to Cd (5 p.p.m. in drinking water) with or without melatonin (3 μg/mL drinking water) for 1 month. In the anterior pituitary, Cd increased lipid peroxidation and mRNA levels for heme oxygenase‐1 (HO‐1) at both time intervals tested (09:00 and 01:00 hr, beginning of rest span and middle of activity span, respectively). Melatonin administration prevented the Cd‐induced increase in both parameters. In the hypothalamus, Cd affected the levels of mRNA for HO‐1 by decreasing it in the evening. Melatonin reduced hypothalamic HO‐1 gene expression. Cd treatment augmented gene expression of nitric oxide synthase (NOS)1 and NOS2 in the pituitary whereas melatonin decreased it, impairing the activity of Cd. Exposure to Cd increased the levels of hypothalamic NOS1 mRNA at 09:00 hr and decreased the levels of NOS2 mRNA at 01:00 hr, with melatonin treatment preventing Cd effects. Cd treatment decreased plasma thyroid‐stimulating hormone levels at both examined times, while melatonin reversed the effect of Cd at 09:00 hr and partially counteracted the effect at 01:00 hr. There were important variations between day and night in the expression of all the genes tested in both tissues. Melatonin treatment was effective reducing all examined effects of Cd, documenting its effectiveness to protect the rat hypothalamic–pituitary axis from the toxic metal effects.
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.
Nonresident Fathers’ Contributions to Adolescent Well‐Being
Authors: King Valarie , Sobolewski Juliana M.
Published: July 2006

Using data from 453 adolescents in Wave 2 of the National Survey of Families and Households, we examine how multiple dimensions of nonresident father involvement are associated with different dimensions of child well‐being. Father‐child relationship quality and responsive fathering are modestly associated with fewer externalizing and internalizing problems among adolescents. The quality of the mother‐child relationship, however, has stronger effects on child well‐being. Nevertheless, even if adolescents have weak ties to mothers, those who have strong ties to nonresident fathers exhibit fewer internalizing problems and less acting out at school than adolescents who have weak ties to both parents. Adolescents are worst off on a range of outcomes when they have weak ties to both their mothers and nonresident fathers.
Pathways to Intergenerational Adolescent Childbearing in a High‐Risk Sample
Authors: Campa Mary I. , Eckenrode John J.
Published: July 2006

Previous research indicates that children of adolescent mothers are more likely to experience an adolescent birth than are children of older mothers. Using a longitudinal sample of 293 high‐risk mothers and their 19‐year‐old children, we investigated mediators of the intergenerational pattern of adolescent childbearing. Results from multigroup path models indicate that the intergenerational effect is (a) significant for children of unmarried mothers above and beyond mother’s prebirth socioeconomic status and education level, (b) fully mediated through early sexual intercourse related to presence of a father figure and early home environment for girls, and (c) partially mediated by early physical development for boys. Relation of findings to current models of early sexual behavior and childbearing is discussed.
Gendered Living Arrangements Among Children With Disabilities
Authors: Cohen Philip N. , Petrescu‐Prahova Miruna
Published: July 2006

Using data on disabilities from the 2000 Census, we found a consistent pattern of living arrangements that leaves children (aged 5 – 15 years) with disabilities living disproportionately with women. Children with disabilities are more likely to live with single parents, and especially their mothers, than are other children. Further, those who do not live with either biological parent are more likely to live in households headed by women than are other children. The results suggest that gendered living arrangements among children with disabilities are a neglected aspect of inequality in caring labor, which is an underpinning of gender inequality in general.
Bore Hole Sampling of Saturated Uncemented Sands and Gravels
Authors: Barton C. M.
Published: July 2006

Bore 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

A 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

The 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

A 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

Successful 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

The 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

Ground‐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

Ground‐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

An 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

Three 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

Due 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

The 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

This 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

Well 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

Large‐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

The 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.
Analysis of the effects of cannabinoids on identified synaptic connections in the caudate‐putamen by paired recordings in transgenic mice
Authors: Freiman Ilka , Anton Alexandra , Monyer Hannah , Urbanski Michal J. , Szabo Bela
Published: July 2006

CB1 cannabinoid receptors are expressed in many neurons in the caudate‐putamen. However, it is not known how the activation of these receptors influences synaptic transmission between different neuron classes. The aim was to establish a method for studying identified synaptic connections in the caudate‐putamen, and to determine the effects of cannabinoids on these connections. Brain slices were prepared from transgenic mice expressing enhanced green fluorescent protein (EGFP) in parvalbumin‐positive fast spiking interneurons (PV‐FSNs). PV‐FSNs were identified based on their fluorescence. Non‐fluorescent medium‐sized neurons were considered to be medium spiny neurons (MSNs). Synaptic transmission was studied by simultaneous patch‐clamp recording from identified neuron pairs. In the case of PV‐FSN → MSN neurotransmission, the synthetic cannabinoid receptor agonist WIN55212‐2 lowered the success rate of transmission and the amplitude of successful postsynaptic events. Analysis of miniature inhibitory postsynaptic currents indicated that WIN55212‐2 inhibited synaptic transmission presynaptically. WIN55212‐2 did not elicit somatodendritic effects in PV‐FSNs: membrane potential, membrane current and evoked firing were not changed. WIN55212‐2 also depressed the MSN → MSN neurotransmission. The inhibitory synaptic input to MSNs was only weakly suppressed by endocannabinoids released by depolarized postsynaptic MSNs. The results show that the combined use of transgenic animals and paired‐recording techniques allows the study of synaptic connections between rare neurons. Using these techniques, we showed that activation of CB1 receptors on axon terminals of (i) PV‐FSNs and (ii) MSNs leads to presynaptic inhibition of GABAergic synaptic transmission between these axons and their postsynaptic targets, the MSNs. The cannabinoids acted preferentially on axon terminals without effects on the somatodendritic region of the neurons.
Three-Dimensional Motion of Sliders Contacting Media
Authors: Kiely James , Hsia Yiao-Tee
Published: July 2006

Characterization of slider motion induced by contact is becoming a critical aspect of developing advanced head-disk interfaces. While vertical motion induced by contact has been studied, very little is known about off- and down-track motions. We have applied three separate laser Doppler vibrometers to measure slider movement in three orthogonal directions simultaneously. We have measured the position of a slider as it undergoes a transition from flying to making full contact with the media surface. We find that slider motion varies considerably with varying levels of contact and that motion in all three directions is considerable. Spectral decomposition is used to identify the vibration modes that are excited in each direction, and we find that for most of the test velocities, modes excited in the vertical direction give rise to motion in the two orthogonal directions. In addition, we present a depiction of the vertical, down-track, and off-track position changes by plotting the position of the slider in real space coordinates to help visualize more completely how the slider moves in space. These trajectories depict the periodic, elliptical path the slider takes and identify how the paths change with contact. Analysis of motion identifies that at some levels of contact, a majority of motion is repeatable, but that nonrepeatable components increase with the amount of contact. Additionally, down-track motion is the only component whose magnitude increases monotonically with increasing contact.
Experimental Characterization of Wheel-Rail Contact Patch Evolution
Authors: Marshall M. B. , Lewis R. , Dwyer-Joyce R. S. , Olofsson U. , Björklund S.
Published: July 2006

The contact area and pressure distribution in a wheel/rail contact is essential information required in any fatigue or wear calculations to determine design life, re-grinding, and maintenance schedules. As wheel or rail wear or surface damage takes place the contact patch size and shape will change. This leads to a redistribution of the contact stresses. The aim of this work was to use ultrasound to nondestructively quantify the stress distribution in new, worn, and damaged wheel-rail contacts. The response of a wheel/rail interface to an ultrasonic wave can be modeled as a spring. If the contact pressure is high the interface is very stiff, with few air gaps, and allows the transmission of an ultrasonic sound wave. If the pressure is low, interfacial stiffness is lower and almost all the ultrasound is reflected. A quasistatic spring model was used to determine maps of contact stiffness from wheel/rail ultrasonic reflection data. Pressure was then determined using a parallel calibration experiment. Three different contacts were investigated; those resulting from unused, worn, and sand damaged wheel and rail specimens. Measured contact pressure distributions are compared to those determined using elastic analytical and numerical elastic-plastic solutions. Unused as-machined contact surfaces had similar contact areas to predicted elastic Hertzian solutions. However, within the contact patch, the numerical models better reproduced the stress distribution, as they incorporated real surface roughness effects. The worn surfaces were smoother and more conformal, resulting in a larger contact patch and lower contact stress. Sand damaged surfaces were extremely rough and resulted in highly fragmented contact regions and high local contact stress.
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

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.
A Protective Immune Response Is Generated in Rainbow Trout by an OmpH-Like Surface Antigen (P18) of
Flavobacterium psychrophilum
Authors: Dumetz Fabien , Duchaud Eric , LaPatra Scott E. , Le Marrec Claire , Claverol Stéphane , Urdaci Maria-C. , Le Hénaff Michel
Published: July 2006

Investigations of the surface characteristics of
Flavobacterium psychrophilum
, an important pathogen of fish, assisted us in identifying a surface protein termed P18. In the current study, we developed a simple and efficient procedure for the purification of this protein by a two-step method. First, P18 was selectively released from flavobacteria by a heat-HEPES treatment of the cells and then subjected to anion-exchange high-performance liquid chromatography. De novo sequencing was used to generate a fragmented peptide spectrum from purified P18. Comparison of two obtained peptide sequences with a partial genome sequence of
F. psychrophilum
(INRA, Jouy-en-Josas, France) identified one gene encoding a 166-amino-acid OmpH-like protein that mostly likely undergoes N-terminal cleavage of the 23-residue signal peptide. The susceptibility of the OmpH-like protein to proteinase K treatment and the bacteriostatic/bactericidal activities of anti-OmpH-like protein antibodies indicated that this protein is actually exposed on the surface of
F. psychrophilum
. Vaccination trials showed that the OmpH-like protein can induce a high titer of anti-OmpH-like protein antibodies which are protective. Taken together, these results suggest that this surface protein produced by
F. psychrophilum
could be used in future vaccine development as a promising candidate antigen.
Facile Recovery of Individual High-Molecular-Weight, Low-Copy-Number Natural Plasmids for Genomic Sequencing
Authors: Williams Laura E. , Detter Chris , Barry Kerrie , Lapidus Alla , Summers Anne O.
Published: July 2006

Sequencing of the large (>50 kb), low-copy-number (<5 per cell) plasmids that mediate horizontal gene transfer has been hindered by the difficulty and expense of isolating DNA from individual plasmids of this class. We report here that a kit method previously devised for purification of bacterial artificial chromosomes (BACs) can be adapted for effective preparation of individual plasmids up to 220 kb from wild gram-negative and gram-positive bacteria. Individual plasmid DNA recovered from less than 10 ml of
Escherichia coli
,
Staphylococcus
, and
Corynebacterium
cultures was of sufficient quantity and quality for construction of high-coverage libraries, as shown by sequencing five native plasmids ranging in size from 30 kb to 94 kb. We also report recommendations for vector screening to optimize plasmid sequence assembly, preliminary annotation of novel plasmid genomes, and insights on mobile genetic element biology derived from these sequences. Adaptation of this BAC method for large plasmid isolation removes one major technical hurdle to expanding our knowledge of the natural plasmid gene pool.
Old Yellow Enzymes Protect against Acrolein Toxicity in the Yeast
Saccharomyces cerevisiae
Authors: Trotter Eleanor W. , Collinson Emma J. , Dawes Ian W. , Grant Chris M.
Published: July 2006

Acrolein is a ubiquitous reactive aldehyde which is formed as a product of lipid peroxidation in biological systems. In this present study, we screened the complete set of viable deletion strains in
Saccharomyces cerevisiae
for sensitivity to acrolein to identify cell functions involved in resistance to reactive aldehydes. We identified 128 mutants whose gene products are localized throughout the cell. Acrolein-sensitive mutants were distributed among most major biological processes but particularly affected gene expression, metabolism, and cellular signaling. Surprisingly, the screen did not identify any antioxidants or similar stress-protective molecules, indicating that acrolein toxicity may not be mediated via reactive oxygen species. Most strikingly, a mutant lacking an old yellow enzyme (
OYE2
) was identified as being acrolein sensitive. Old yellow enzymes are known to reduce α,β-unsaturated carbonyl compounds in vitro, but their physiological roles have remained uncertain. We show that mutants lacking
OYE2
, but not
OYE3
, are sensitive to acrolein, and overexpression of both isoenzymes increases acrolein tolerance. Our data indicate that
OYE2
is required for basal levels of tolerance, whereas
OYE3
expression is particularly induced following acrolein stress. Despite the range of α,β-unsaturated carbonyl compounds that have been identified as substrates of old yellow enzymes in vitro, we show that old yellow enzymes specifically mediate resistance to small α,β-unsaturated carbonyl compounds, such as acrolein, in vivo.
The
Caenorhabditis elegans
ABL-1 Tyrosine Kinase Is Required for
Shigella flexneri
Pathogenesis
Authors: Burton Elizabeth A. , Pendergast Ann Marie , Aballay Alejandro
Published: July 2006

Shigellosis is a diarrheal disease caused by the gram-negative bacterium
Shigella flexneri
. Following ingestion of the bacterium,
S. flexneri
interferes with innate immunity, establishes an infection within the human colon, and initiates an inflammatory response that results in destruction of the tissue lining the gut. Examination of host cell factors required for
S. flexneri
pathogenesis in vivo has proven difficult due to limited host susceptibility. Here we report the development of a pathogenesis system that involves the use of
Caenorhabditis elegans
as a model organism to study
S. flexneri
virulence determinants and host molecules required for pathogenesis. We show that
S. flexneri-
mediated killing of
C. elegans
correlates with bacterial accumulation in the intestinal tract of the animal. The
S. flexneri
virulence plasmid, which encodes a type III secretory system as well as various virulence determinants crucial for pathogenesis in mammalian systems, was found to be required for maximal
C. elegans
killing. Additionally, we demonstrate that ABL-1, the
C. elegans
homolog of the mammalian c-Abl nonreceptor tyrosine kinase ABL1, is required for
S. flexneri
pathogenesis in nematodes. These data demonstrate the feasibility of using
C. elegans
to study
S. flexneri
pathogenesis in vivo and provide insight into host factors that contribute to
S. flexneri
pathogenesis.
Biofilm Formation by
Bacillus cereus
Is Influenced by PlcR, a Pleiotropic Regulator
Authors: Hsueh Yi-Huang , Somers Eileen B. , Lereclus Didier , Wong Amy C. Lee
Published: July 2006

The Δ
plcR
mutant of
Bacillus cereus
strain ATCC 14579 developed significantly more biofilm than the wild type and produced increased amounts of biosurfactant. Biosurfactant production is required for biofilm formation and may be directly or indirectly repressed by PlcR, a pleiotropic regulator. Coating polystyrene plates with surfactin, a biosurfactant from
Bacillus subtilis
, rescued the deficiency in biofilm formation by the wild type.
Phage Display of an Intracellular Carboxylesterase of
Bacillus subtilis
: Comparison of Sec and Tat Pathway Export Capabilities
Authors: Dröge Melloney J. , Boersma Ykelien L. , Braun Peter G. , Buining Robbert Jan , Julsing Mattijs K. , Selles Karin G. A. , van Dijl Jan Maarten , Quax Wim J.
Published: July 2006

Using the phage display technology, a protein can be displayed at the surface of bacteriophages as a fusion to one of the phage coat proteins. Here we describe development of this method for fusion of an intracellular carboxylesterase of
Bacillus subtilis
to the phage minor coat protein g3p. The carboxylesterase gene was cloned in the g3p-based phagemid pCANTAB 5E upstream of the sequence encoding phage g3p and downstream of a signal peptide-encoding sequence. The phage-bound carboxylesterase was correctly folded and fully enzymatically active, as determined from hydrolysis of the naproxen methyl ester with

K
m

values of 0.15 mM and 0.22 mM for the soluble and phage-displayed carboxylesterases, respectively. The signal peptide directs the encoded fusion protein to the cell membrane of
Escherichia coli
, where phage particles are assembled. In this study, we assessed the effects of several signal peptides, both Sec dependent and Tat dependent, on the translocation of the carboxylesterase in order to optimize the phage display of this enzyme normally restricted to the cytoplasm. Functional display of
Bacillus
carboxylesterase NA could be achieved when Sec-dependent signal peptides were used. Although a Tat-dependent signal peptide could direct carboxylesterase translocation across the inner membrane of
E. coli
, proper assembly into phage particles did not seem to occur.