bluuebunny/crossref_metadata_2025 huggingface dataset:
The Selection of a Computer for a Wide Range of Ground‐Water Related Applications
Authors: Holzschuh Joseph C.
Published: July 2006

Due to inexperience on the part of those assigned to purchase computer facilities for water resource tasks, a poor or unacceptable choice of equipment is often made. The political realities of introducing new computing equipment into a firm which has several departments which will vie for the use of that equipment must be faced.

The size, complexity, and capabilities of the machine to be purchased as well as the software and personnel involved must be considered carefully in relation to the specific tasks at hand. The bidding process, demonstrations, and reference materials offer some assistance in deciding among the often confusing array of systems available on the market.
Regional Hydrogeologic Concepts of Homoclinal Flanks
Authors: LeGrand Harry E. , Pettyjohn Wayne A.
Published: July 2006

A worldwide overview of structural geologic settings indicates that the homoclinal flank is one of the most widespread and common of hydrogeologic systems. The geomorphic conditions on the structural basin flanks correlate with distinctive ground‐water flow patterns.

Relatively undisturbed coastal plain formations and all other sedimentary rocks that are arched or warped into marginal basins are flanked at the land surface by dynamic hydrologie systems. Their aquifers, on a local scale considered to be horizontal, extend into regional tilted and beveled systems. Dips of strata that are only slightly greater than the gross slope of the land surface, but in the same direction, are prominent and produce exposures of alternating permeable and less permeable beveled formations in elongated regional bands. Differential erosion has led to cuesta landscapes in varying degrees. On these step‐like plateaus, subsequent and consequent streams have distinctive streamflow characteristics.

One common type of hydrologic system is that dominated by consequent streams flowing down the structural basin, generally through reentrants in scarps. These streams capture much ground‐water runoff at the lowest exposed point in the aquifer (at the apex of the V that the stream makes with an overlying aquitard). The discharging ground water forms a natural cone of depression in the aquifer, representing a chief core of the ground‐water circulation system. An example is the large cone of depression in a Cretaceous sand aquifer in the Savannah River valley 15 to 25 kilometers south of Augusta, Georgia.

Graphic modeling of hydrogeologic systems in homoclinal flanks explains the uneven distribution of ground‐water discharge. Stretches of each stream can be classified readily according to the degree of ground‐water discharge on a homoclinal flank.
Hydraulic Connection Between Lake Michigan and a Shallow Ground‐Water Aquifera
Authors: Cherkauer D. S. , Zvibleman B.
Published: July 2006

Pumping from a dolomite aquifer adjacent to Lake Michigan has reversed the natural hydraulic gradient so that lake water has been induced to flow into the aquifer. Because lake water is muchlower in dissolved solids than the ambient ground water, the induced recharge is traceable as adistinct plume of high‐quality water over a mile long. The configuration of the plume allows interpretation of the hydraulic connection between the lake and the aquifer. Most of the induced recharge enters the aquifer through the lake bed at locations where the most permeable parts ofthe aquifer are overlain by relatively thin lake‐bed sediments which, in turn, are at least partly sand and gravel. It continues inland along zones of high hydraulic conductivity.
Inverse Solutions of the Theis Equation Determined with Programmable Calculators I—Single Parameter Calculations
Authors: Grimestad Garry
Published: July 2006

This is the first of two articles on calculator programs for inverse solutions of the Theis equation.

Newton's method is used to solve the Theis equation in terms of its principal well function argument parameters. The resulting iteration formulas are incorporated in an otherwise conventional polynomial‐based drawdown program for Hewlett Packard HP 67/97 calculators.

The calculator program can solve, in addition to conventional drawdown problems, those problems requiring treatment of the time, distance, storage coefficient, or transmissivity as a dependent variable. Example calculations are shown and program modifications providing for series‐based well function calculations are appended.
Hydrochemical Facies in a Tertiary Basin in the Milligan Canyon Area, Southwest Montana
Authors: Krothe Noel C. , Bergeron Marcel P.
Published: July 2006

Equilibria studies of ground‐water chemistry in a synclinal basin at Three Forks, Montana indicate that most waters in the Tertiary sediments and Madison Group carbonates are calcium‐bicarbonate, or calcium‐sulfate waters which are supersaturated with respect to calcite. Calcium concentrations range from 13 to 426 mg/l, bicarbonate concentrations range from 112 to 328 mg/l and sulfate concentration varies between 29 to 114 mg/l. Sodium concentration is between 10 and 312 mg/l, producing sodium‐bicarbonate waters in some areas.

Water‐level data were used to construct a potentiometric map that shows flow direction to the east. The water evolution along the flow path is from calcium‐bicarbonate in the recharge areas, to calcium‐sulfate in the center of the area, and finally sodium‐bicarbonate in the discharge area. This evolutionary sequence can be explained by calcite, dolomite and gypsum dissolution, ion exchange, sulfate reduction and dilution by recharging waters from the Elkhorn Mountains Volcanics.
Hydrologic Testing of Tight Zones in Southeastern New Mexico
Authors: Dennehy Kevin F. , Davis Paul A.
Published: July 2006

Increased attention is being directed toward the investigation of tight zones in relation to the storage and disposal of hazardous wastes. Shut‐in tests, slug tests, and pressure‐slug tests are being used at the proposed Waste Isolation Pilot Plant site, located in southeastern New Mexico, to evaluate the fluid‐transmitting properties of several zones above the proposed repository zone. Apparatus used to conduct these tests includes a pressure‐transducer system connected to a recording device at the land surface. All three testing methods were used in various combinations to obtain values for the hydraulic properties of the test zones. Multiple testing on the same zone produced similar results. Transmissivities determined by these tests range from 0.00001 to 10 feet squared per day (.000001 to 1 meter squared per day).
Deviations from Classical Behaviour in Pumping Test Analysis
Authors: del Mar Gonzalez Maria , Rushton K. R.
Published: July 2006

This paper discusses certain of the reasons for deviations from the classical type curve behaviour during pumping tests. A particular series of pumping tests in a confined limestone aquifer is considered; the tests include a step test, a 3‐day test and a 71‐day test. Using a radial flow numerical model, the influences of transmissivity, storage coefficient altering with radius, a neighbouring baseload borehole and a distant unconfined boundary are each considered. The baseload borehole is shown to have a significant effect on both abstraction and recovery response for the 3‐day test, while both the baseload borehole and the unconfined boundary modify the response for the 71‐day test.
A Method of Performing Response Tests on Highly Permeable Aquifers
Authors: Prosser Donald W.
Published: July 2006

Response or “slug” tests to determine the hydraulic conductivity of in situ earth materials are often difficult to perform in situations of very high hydraulic conductivity. In small‐diameter standpipes, rapid response to the induced head difference, often in a matter of seconds, is difficult to measure with conventional well sounders. Instantaneous induction of a known head difference is also a major problem when dealing with very fast response times. A method of performing such tests has been developed, utilizing electronic pressure transducers to monitor the response to a pneumatically induced head. Increased air pressure within the standpipe causes displacement of the water column to accommodate the air pressure. Once the aquifer has re‐equilibrated in this condition, sudden release of the air pressure constitutes an instantaneously induced head difference. The response measured by the electronic pressure transducer can be recorded digitally or by an analog chart recorder with fast paper speed. This method has been used to measure basic time lags in the order of several seconds. The use of electronic pressure transducers and pneumatically induced head differences will allow accurate measurements in situations of higher hydraulic conductivity than would be possible using common response testing techniques.
The Use of Ground‐Water Flow Models for Estimating Lake Seepage Rates
Authors: Munter James A. , Anderson Mary P.
Published: July 2006

Ground‐water flow models developed for the flow systems around Bass Lake and Nepco Lake, Wisconsin, show that models can be useful tools for estimating lake seepage rates. A two‐dimensional profile model for Bass Lake illustrates that the ratio of horizontal to vertical hydraulic conductivity of the aquifer around the lake is related to both the magnitude of vertical hydraulic gradients near the lake and the distribution of seepage from the lake as a function of distance from shore. The model also shows that it is important to know the vertical hydraulic conductivity of littoral lake‐bed sediments to estimate lake seepage rates.

A three‐dimensional model constructed for an unusual ground‐water flow system around Nepco Lake provides a more realistic simulation of the flow system than does a comparable two‐dimensional model. Both models were useful for identifying additional data that could be used to quantify the ground‐water portion of the lake's water budget more accurately. It is suggested that a combination of two‐and/or three‐dimensional models could be used to estimate seepage rates at many lakes for which sufficient data exist.
Statistical Considerations and Sampling Techniques for Ground‐Water Quality Monitoring
Authors: Nelson James D. , Ward Robert C.
Published: July 2006

Recent emphasis on the need to protect ground‐water quality has resulted in an increased interest in ground‐water quality monitoring, particularly that monitoring performed in support of a regulatory ground‐water quality management program. Such monitoring must involve intensive surveys or special studies, as well as routine trend types of sampling. In both cases, adequate monitoring strategies require careful consideration of the statistical aspects of sampling theory.

The purpose of this paper is to present statistical concepts that should be incorporated in the initial planning of a ground‐water quality monitoring program.

The means of incorporating statistical theory into ground‐water quality monitoring suggested in this paper involves selecting the number of samples required based on a specified confidence interval about the mean of the variable under consideration. This approach requires that the variance of the sample mean be known. The expression for Var(x̄) will depend on the correlation structure of the population in question. If the observations taken can be assumed independent in both space and time (i.e., no spatial or serial correlation exists), then the number of samples required can be determined in a very straightforward manner. However, if the samples are correlated, part of the information contained in one observation will be contained in other observations as well. As a result, the sample size must be increased in order to achieve the same level of information that would be obtained in uncorrelated observations.

Various sampling techniques can be employed in a ground‐water monitoring plan, including simple random sampling, systematic sampling, and stratified random sampling. Each technique has certain advantages and disadvantages with regard to ground‐water monitoring. An overall monitoring program should incorporate the most effective sampling techniques in order to achieve optimum information content from a minimum number of samples.
Salt‐Water Intrusion in the Costa de Hermosillo, Mexico: A Numerical Analysis of Water Management Proposals
Authors: Andrews Robert W.
Published: July 2006

As a result of anthropogenic discharges of ground water far exceeding natural recharge, the Costa de Hermosillo aquifer is being actively intruded by salt water. Because this aquifer is utilized as the sole source of irrigation water for one of Mexico's principal agricultural districts, the application of any future management scheme to control this intrusion must be closely evaluated prior to implementation. A hydrologic and water quality simulation model is applied to the Costa de Hermosillo aquifer to assess the areal and temporal variations in head, velocity, and concentration as a result of changes in the present discharge distribution. The known hydrologic conditions are reproduced as a means of calibrating the model. Only qualitative statements on the future behavior of the aquifer are possible due to the uncertainty of the magnitude of various aquifer parameters and initial conditions. The model employed in this study is found to be a useful technique for the analysis of the effects of the proposed pumping stresses.
Oestrogen status in relation to the early training responses in human thumb adductor muscles
Authors: Onambele G. N. L. , Bruce S. A. , Woledge R. C.
Published: July 2006

Aims:  The aims of this study were to identify the mechanisms for the early response to training in women of different oestrogen status and to determine whether any oestrogen and exercise effects on these would be additive.

Methods:  We monitored training (ten 5‐s contractions per day for 12 weeks)‐induced changes in the size, strength, voluntary activation capacity and index of crossbridge force state (i.e. rapid stretch to isometric torque ratio), in the thumb adductor muscles of postmenopausal [eight who had never used, and 14 who were using, hormone replacement therapy (HRT)] and seven premenopausal eumenorrhoeic women. The contralateral untrained muscle was used as a control.

Results:  There was a significant effect of oestrogen status on the magnitude of training‐induced strength increment, with the non‐HRT postmenopausal group exhibiting the greatest benefits (28 ± 6%, P = 0.024) from training. There were no significant or commensurate changes in either cross‐sectional area or voluntary activation capacity. The index of crossbridge force state improved most in the no‐HRT group (19 ± 7%, P < 0.05).

Conclusions:  Presence, rather than absence of oestrogen, is associated with relatively higher muscle function which limits the potential for any further training‐induced increments in muscle performance, as would be expected if the muscle strengthening actions of training and oestrogen share a common, partially saturable physiological pathway. The mechanism that is involved in the early training‐induced strength increment in the three differing oestrogen groups cannot be due to increased size or recruitment. It would appear instead that increased motor unit firing frequency is involved.
Mycoplasma felisarthritis in two cats
Authors: Liehmann L. , Degasperi B. , Spergser J. , Niebauer G. W.
Published: July 2006

This report describes the occurrence of non‐weightbearing lameness caused byMycoplasma felismonoarthritis in two, immunocompetent, European, shorthair adult cats with a suspected history of trauma. Clinical signs recurred after conservative treatment. The joints were treated surgically andM feliswas identified as the causative agent for the monoarthritis. Medication with 10 mg/kg doxycycline twice daily was initiated according to susceptibility testing. One cat underwent further joint flushing after two weeks; both the cats recovered completely after eight and nine weeks, respectively. The findings suggest thatM felis, in addition to being an agent associated with conjunctivitis in cats, is able to act as a pathogen in other tissues and cause arthritis even in immunocompetent cats.
Comparison of radiography and magnetic resonance imaging for evaluating the extent of nasal neoplasia in dogs
Authors: Petite A. F. B. , Dennis R.
Published: July 2006

Objectives:Magnetic resonance imaging (MRI) is increasingly used in veterinary practice and, in some centres, is part of the diagnostic work‐up of small animals with nasal disease. However, there are no published studies which critically evaluate the use of magnetic resonance imaging for this purpose. The purpose of this work was to assess the changes seen using magnetic resonance imaging and to compare them with radiography.

Methods:The study included 12 dogs that had undergone both radiography and magnetic resonance imaging of the nasal cavity and had a histopathological diagnosis of malignant nasal neoplasia. Two pairs of board‐certified radiologists scored the radiographs and the MRI scans, evaluating 10 signs of abnormality using a simple scoring system. Magnetic resonance imaging features were described in detail, and radiographic and magnetic resonance imaging scores for each sign as well as total scores were compared.

Results:Magnetic resonance imaging often showed that the tumour was more extensive than it had appeared on radiography but occasionally showed that radiographs had overestimated its size. Although radiography was reliable for assessment of the presence and size of a mass and for the extent of turbinate destruction, it usually failed to show occlusion of the major airway passages that were evident on magnetic resonance imaging. Extension of the tumour into the opposite nasal cavity, frontal sinus, orbit and cranial cavity was shown much better on magnetic resonance imaging.

ClinicalSignificance:Minor but significant extension beyond the nasal cavity, which is important for treatment planning and prognosis, requires magnetic resonance imaging for demonstration, although radiography shows major changes reliably.
The inotropic effect of cardioactive glycosides in ventricular myocytes requires Na+–Ca2+ exchanger function
Authors: Altamirano Julio , Li Yanxia , DeSantiago Jaime , Piacentino Valentino , Houser Steven R. , Bers Donald M.
Published: July 2006

Glycoside‐induced cardiac inotropy has traditionally been attributed to direct Na+–K+‐ATPase inhibition, causing increased intracellular [Na+] and consequent Ca2+ gain via the Na+–Ca2+ exchanger (NCX). However, recent studies suggested alternative mechanisms of glycoside‐induced inotropy: (1) direct activation of sarcoplasmic reticulum Ca2+ release channels (ryanodine receptors; RyRs); (2) increased Ca2+ selectivity of Na+ channels (slip‐mode conductance); and (3) other signal transduction pathways. None of these proposed mechanisms requires NCX or an altered [Na+] gradient. Here we tested the ability of ouabain (OUA, 3 μm), digoxin (DIG, 20 μm) or acetylstrophanthidin (ACS, 4 μm) to alter Ca2+ transients in completely Na+‐free conditions in intact ferret and cat ventricular myocytes. We also tested whether OUA directly activates RyRs in permeabilized cat myocytes (measuring Ca2+ sparks by confocal microscopy). In intact ferret myocytes (stimulated at 0.2 Hz), DIG and ACS enhanced Ca2+ transients and cell shortening during twitches, as expected. However, prior depletion of [Na+]i (in Na+‐free, Ca2+‐free solution) and in Na+‐free solution (replaced by Li+) the inotropic effects of DIG and ACS were completely prevented. In voltage‐clamped cat myocytes, OUA increased Ca2+ transients by 48 ± 4% but OUA had no effect in Na+‐depleted cells (replaced by N‐methyl‐d‐glucamine). In permeabilized cat myocytes, OUA did not change Ca2+ spark frequency, amplitude or spatial spread (although spark duration was slightly prolonged). We conclude that the acute inotropic effects of DIG, ACS and OUA (and the effects on RyRs) depend on the presence of Na+ and a functional NCX in ferret and cat myocytes (rather than alternate Na+‐independent mechanisms).
Short‐term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance
Authors: Gibala Martin J. , Little Jonathan P. , Van Essen Martin , Wilkin Geoffrey P. , Burgomaster Kirsten A. , Safdar Adeel , Raha Sandeep , Tarnopolsky Mark A.
Published: July 2006

Brief, intense exercise training may induce metabolic and performance adaptations comparable to traditional endurance training. However, no study has directly compared these diverse training strategies in a standardized manner. We therefore examined changes in exercise capacity and molecular and cellular adaptations in skeletal muscle after low volume sprint‐interval training (SIT) and high volume endurance training (ET). Sixteen active men (21 ± 1 years, ) were assigned to a SIT or ET group (n= 8 each) and performed six training sessions over 14 days. Each session consisted of either four to six repeats of 30 s ‘all out’ cycling at ∼250% with 4 min recovery (SIT) or 90–120 min continuous cycling at ∼65% (ET). Training time commitment over 2 weeks was ∼2.5 h for SIT and ∼10.5 h for ET, and total training volume was ∼90% lower for SIT versus ET (∼630 versus∼6500 kJ). Training decreased the time required to complete 50 and 750 kJ cycling time trials, with no difference between groups (main effects, P≤ 0.05). Biopsy samples obtained before and after training revealed similar increases in muscle oxidative capacity, as reflected by the maximal activity of cytochrome c oxidase (COX) and COX subunits II and IV protein content (main effects, P≤ 0.05), but COX II and IV mRNAs were unchanged. Training‐induced increases in muscle buffering capacity and glycogen content were also similar between groups (main effects, P≤ 0.05). Given the large difference in training volume, these data demonstrate that SIT is a time‐efficient strategy to induce rapid adaptations in skeletal muscle and exercise performance that are comparable to ET in young active men.
Functional properties of spontaneous IPSCs and glycine receptors in rod amacrine (AII) cells in the rat retina
Authors: Gill Silje Bakken , Veruki Margaret Lin , Hartveit Espen
Published: July 2006

AII amacrine cells play a crucial role in retinal signal transmission under scotopic conditions. We have used rat retinal slices to investigate the functional properties of inhibitory glycine receptors on AII cells by recording spontaneous IPSCs (spIPSCs) in whole cells and glycine‐evoked responses in outside‐out patches. Glycinergic spIPSCs displayed fast kinetics with an average 10–90% rise time of ∼500 μs, and a decay phase best fitted by a double‐exponential function with τfast∼ 4.8 ms (97.5% amplitude contribution) and τslow∼ 33 ms. Decay kinetics were voltage dependent. Ultrafast application of brief (∼2–5 ms) pulses of glycine (3 mm) to patches, evoked responses with fast deactivation kinetics best fitted with a double‐exponential function with τfast∼ 4.6 ms (85% amplitude contribution) and τslow∼ 17 ms. Double‐pulse experiments indicated recovery from desensitization after a 100‐ms pulse of glycine with a double‐exponential time course (τfast∼ 71 ms and τslow∼ 1713 ms). Non‐stationary noise analysis of spIPSCs and patch responses, and directly observed channel gating yielded similar single‐channel conductances (∼41 to ∼47 pS). In addition, single‐channel gating occurred at ∼83 pS. These results suggest that the fast glycinergic spIPSCs in AII cells are probably mediated by α1β heteromeric receptors with a contribution from α1 homomeric receptors. We hypothesize that glycinergic synaptic input may target the arboreal dendrites of AII cells, and could serve to shunt excitatory input from rod bipolar cells and transiently uncouple the transcellular current through electrical synapses between AII cells and between AII cells and ON‐cone bipolar cells.
Simultaneous inhibition of caudal medullary raphe and retrotrapezoid nucleus decreases breathing and the CO2 response in conscious rats
Authors: Li Aihua , Zhou Shawn , Nattie Eugene
Published: July 2006

The medullary raphe (MR) and the retrotrapezoid nucleus (RTN) in the ventral medulla are two of many central chemoreceptor sites. We examine their combined function in conscious rats by focal inhibition using microdialysis. Inhibition of RTN neurons with the GABAA receptor agonist muscimol, with simultaneous dialysis of artificial cerebrospinal fluid (ACSF) in or near to the caudal MR, causes hypoventilation (decrease in the ratio of minute ventilation to oxygen consumption, ) and reduces the ventilatory response to 7% CO2 by 24%. Inhibition of caudal MR serotonergic neurons with the 5‐HT1A receptor agonist (R)‐(+)‐8‐hydroxy‐2(di‐n‐propylamino)tetralin (8‐OH‐DPAT), with simultaneous dialysis of ACSF in or near to the RTN, causes hypoventilation but has no significant effect on the CO2 response. Inhibition of both the RTN and the caudal MR simultaneously produces enhanced hypoventilation and a 51% decrease in the CO2 response. The effects of treatment on the CO2 response are similar in wakefulness and in non‐rapid eye movement sleep. Comparison of the effect of 8‐OH‐DPAT microdialysed into a more rostral portion of the MR, where the CO2 response is reduced by 22%, demonstrates heterogeneity within the MR of the function of serotonergic neurons in breathing. We conclude that serotonergic neurons within the caudal MR provide a non‐CO2‐dependent tonic drive to breathe and potentiate the effects of RTN neurons that contribute to a resting chemical ‘drive to breathe’ as well as the response to added CO2. These effects of caudal MR serotonergic neurons could be at a chemoreceptor site, e.g. the RTN, or at ‘downstream’ sites involved in rhythm and pattern generation.
Functional role of store‐operated and stretch‐activated channels in murine adult skeletal muscle fibres
Authors: Ducret Thomas , Vandebrouck Clarisse , Cao My Linh , Lebacq Jean , Gailly Philippe
Published: July 2006

In skeletal muscle, Ca2+ is implicated in contraction, and in regulation of gene expression. An alteration of [Ca2+]i homeostasis is responsible, at least partially, for the muscle degeneration that occurs after eccentric contractions in Duchenne muscular dystrophy, a disease characterized by the loss of the cytoskeletal protein dystrophin. Using patch clamp in the cell‐attached configuration, we characterized the store‐operated channels (SOCs) and the stretch‐activated channels (SACs) present in isolated mouse skeletal muscle. SOCs were voltage independent, had a unitary conductance between 7 and 8 pS (110 mm Ca2+ in the pipette), and their open probability increased when the sarcoplasmic reticulum was depleted by thapsigargin. These SOCs were identical to those previously described in the pathophysiology of Duchenne muscular dystrophy. Under the same experimental conditions, we detected a channel activity that was increased by applying a negative pressure to the patch electrode. The SACs responsible for this current had the same unitary conductance and current–voltage relationship as those observed for SOCs. SOCs and SACs had a similar sensitivity to pharmacological agents such as Gd3+, SKF‐96365, 2‐aminoethoxydiphenyl borate and GsMTx4 toxin. Moreover, stimulation with IGF‐1 increased the occurrence of the activity of both channel types. Together, these observations suggest that SOCs and SACs might belong to the same population or share common constituents. From a functional point of view, treatment of soleus muscle with SKF‐96365 or GsMTx4 toxin increased its sensitivity to a fatigue protocol, suggesting that the influx of Ca2+ that occurs through these channels during contraction is also involved in force maintaining during repeated stimulations.
Suppression of hippocampal plasticity‐related gene expression by sleep deprivation in rats
Authors: Guzman‐Marin Ruben , Ying Zhe , Suntsova Natalia , Methippara Melvi , Bashir Tariq , Szymusiak Ronald , Gomez‐Pinilla Fernando , McGinty Dennis
Published: July 2006

Previous work shows that sleep deprivation impairs hippocampal‐dependent learning and long‐term potentiation (LTP). Brain‐derived neurotrophic factor (BDNF), cAMP response‐element‐binding (CREB) and calcium–calmodulin‐dependent protein kinase II (CAMKII) are critical modulators of hippocampal‐dependent learning and LTP. In the present study we compared the effects of short‐ (8 h) and intermediate‐term (48 h) sleep deprivation (SD) on the expression of BDNF and its downstream targets, Synapsin I, CREB and CAMKII in the neocortex and the hippocampus. Rats were sleep deprived using an intermittent treadmill system which equated total movement in the SD and control treadmill animals (CT), but permitted sustained periods of rest in CT animals. Animals were divided into SD (treadmill schedule: 3 s on/12 s off) and two treadmill control groups, CT1 (15 min on/60 min off) and CT2 (30 min on/120 min off – permitting more sustained sleep). Real‐time Taqman RT‐PCR was used to measure changes in mRNA; BDNF protein levels were determined using ELISA. In the hippocampus, 8 h treatments reduced BDNF, Synapsin I, CREB and CAMKII gene expression in both SD and control groups. Following 48 h of experimental procedures, the expression of all these four molecular markers of plasticity was reduced in SD and CT1 groups compared to the CT2 and cage control groups. In the hippocampus, BDNF protein levels after 8 h and 48 h treatments paralleled the changes in mRNA. In neocortex, neither 8 h nor 48 h SD or control treatments had significant effects on BDNF, Synapsin I and CAMKII mRNA levels. Stepwise regression analysis suggested that loss of REM sleep underlies the effects of SD on hippocampal BDNF, Synapsin I and CREB mRNA levels, whereas loss of NREM sleep underlies the effects on CAMKII mRNA.
A Comprehensive Method to Predict Wear and to Define the Optimum Geometry of Fretting Surfaces
Authors: Gallego L. , Nélias D. , Jacq C.
Published: July 2006

This paper presents a fast and robust three-dimensional contact computation tool taking into account the effect of cyclic wear induced from fretting solicitations under the gross slip regime. The wear prediction is established on a friction-dissipated energy criteria. The material response is assumed elastic. The contact solver is based on the half-space assumption and the algorithm core is similar to the one originally proposed by Kalker (1990, Three Dimensional Elastic Bodies in Rolling Contact, Kluwer, Dordrecht) for normal loading. In the numerical procedure the center of pressure may be imposed. The effect of surface shear stress is considered through a Coulomb friction coefficient. The conjugate gradient scheme presented by Polonsky and Keer (1999, Wear, 231, pp. 206–219) and an improved fast Fourier transform (FFT) acceleration technique similar to the one developed by Liu et al. (2000, Wear, 243, pp. 101–111) are used. Results for elementary geometries in the gross slip regime are presented. It is shown that the surface geometry influences the contact pressure and surface shear stress distributions found after each loading cycle. It is also shown that wear tends to be uniformly distributed. This process continuously modifies the micro- and macrogeometry of the rubbing surfaces, leading after a given number of cycles to (i) an optimum or ideal contact geometry and (ii) a prediction of wear.
On the Optimum Groove Geometry for Herringbone Grooved Journal Bearings
Authors: Gad A. M. , Nemat-Alla M. M. , Khalil A. A. , Nasr A. M.
Published: July 2006

Recently, herringbone-grooved journal bearings have had important applications in miniature rotating machines. The scribed grooves, on either the rotating or stationary member of the bearing, can pump the lubricant inward, which generates supporting stiffness and improves the dynamic stability, especially for concentric operation. Most of the previous investigations that dealt with herringbone grooved journal bearings and grooved thrust bearings were theoretical. Few experimental attempts for the investigation of the performance characteristics of herringbone grooved journal bearings (HGJBs) and grooved thrust bearings have been done. All these investigations concentrated on rectangular and circular groove profiles of HGJBs. In order to improve the performance characteristics of HGJBs, a new design of the groove profile, the beveled-step groove profile, is introduced. The introduced groove profile is capable of increasing the pressure recovery at the divergence of the flow over the step. In addition, it increases the amount of oil pumped inward over the circular groove profile. Optimization processes were carried out experimentally, in order to obtain the optimal geometry of the introduced groove profile. The optimum geometrical parameters of the groove (groove angle α, groove width ratio β, and groove depth ratio Γ) are 29deg, 0.5, and 2.0, respectively, which give maximum radial force and maximum radial stiffness of the beveled-step HGJB. In order to check the effectiveness of the introduced beveled-step groove profile, the obtained results were compared with that for rectangular groove profile. The comparison shows that the introduced beveled-step HGJBs have higher radial force, higher load carrying capacity, and lower friction torque than the rectangular HGJBs.
Bump Foil Damping Using a Simplified Model
Authors: Swanson Erik E.
Published: July 2006

Foil bearings are a key enabling technology for advanced and oil-free rotating machinery. In certain applications, they provide a level of performance that is difficult or impossible to match with other technologies. A number of reasonably successful analytical techniques to predict bearing load capacity, power loss, and stiffness have been developed. Prediction of damping, however, has remained problematic. This work presents a fresh look at the damping problem. Using a simplified representation of a bump foil, this work considers explicitly adding the load dependence of the friction force. This approach is shown to provide a good match to previous experimental data. Parametric study results for the various model parameters are presented to examine the characteristics of this model. It is concluded that the load-dependent frictional force is important to consider for a bump foil damping model.
An Experimental Study on the Impact of Interface Temperature on Thermally Induced Wear Transitions in Dry Sliding
Authors: Schneider Daryl S. , Stephens Lyndon S.
Published: July 2006

Premature failure of materials in sliding contact is often a result of the buildup of frictional heat at the contact interface. The interface temperature is an important parameter affecting the friction and wear process, and it is a function of the operating conditions as well as the heat that is dissipated through the material pair and the nearby surroundings. Possible solutions to alleviate thermal wear mechanisms include using more thermally robust materials and providing better cooling or heat dissipation to reduce the elevated temperatures. The latter is the subject of this paper. The micro heat sink ring (μHSR) is a patented approach to interface cooling in which a micro heat sink is constructed within millimeters of the contact interface. The ramifications of this are that temperature can be treated during wear testing as an independent variable and is only a very small function of speed and load. Using this approach, this work investigates the impact of the μHSR on the wear behavior of a tungsten carbide and carbon graphite material pair under dry running conditions at various rotational speeds and face pressures. Ring-on-ring experiments are performed using a thrust washer rotary tribometer within and in excess of the PV limit of the material pair (17.5MPa*m∕s). Results show the potential of the μHSR to allow for reliable operation of materials in sliding contact in harsh operating conditions. The ability to reduce the interface temperature shows a shift in the region of acceptable operating parameters normally defined for the material pair. This shift is attributed to the prevention of the onset of thermally induced wear transitions and thermal failures otherwise prone to occur under certain operating conditions.
Bifurcation Analysis of a Flexible Rotor Supported by Two Fluid-Film Journal Bearings
Authors: Wang J. K. , Khonsari M. M.
Published: July 2006

The effects of rotor stiffness on the bifurcation regions of a flexible rotor supported by two identical fluid-film journal bearings are presented. It is shown that the rotor stiffness has a pronounced influence on the bifurcation characteristics at the instability threshold speed. For short bearings, two bifurcation regions exist if the dimensionless rotor stiffness K¯⩾4.3. On the other hand, three bifurcation regions exist if the dimensionless rotor stiffness K¯<4.3. Information is presented that allows one to easily predict both the instability threshold speed and its bifurcation type of a rotor-bearing system with any specific set of operating parameters. The results presented have been verified by laboratory experiments as well as several published results in the open literature. Several examples are presented to illustrate the application of the results for design purposes.
The Pressure-Viscosity Coefficient for Newtonian EHL Film Thickness With General Piezoviscous Response
Authors: Bair Scott , Liu Yuchuan , Wang Q. Jane
Published: July 2006

There has been a long-standing need for a piezoviscous parameter αfilm that, together with the ambient viscosity μ0, will completely quantify the Newtonian rheology so that the film thickness for liquids that do not shear-thin in the inlet may be calculated as h=h(μ0,αfilm,…), regardless of the details of the pressure-viscosity response. It seems that Blok’s reciprocal asymptotic isoviscous pressure has certain advantages over the conventional pressure-viscosity coefficient, which is poorly suited for this purpose. The first detailed review of piezoviscous models for low pressures is provided. A simulation code that is apparently stable for all realistic pressure-viscosity response was utilized with diverse piezoviscous models and model liquids to develop a satisfactory definition of αfilm that reads αfilm=[1−exp(−3)]∕[∫03∕α*μ(0)dp∕μ(p)]; 1∕α*=∫0∞μ(0)dp∕μ(p). In the case of μ=μ0exp(αp),αfilm=α and formulas are provided for other models.
Enhancing Tribological Conditions in Tube Hydroforming by Using Textured Tubes
Authors: Ngaile Gracious , Gariety Mark , Altan Taylan
Published: July 2006

The effects of textured tubes on the tribological performance in tube hydroforming (THF) are discussed. Textured surfaces, namely sand blasted, knurled, electrical discharge machined (EDM), and as rolled surfaces, were tested under various interface pressure conditions. Sand blasted textured tubes were found to have the best tribological performance. The study has demonstrated that the increase in the interface pressure between the tube and the die can result in either lower or higher interface friction depending on the surface texture conditions. The study has also shown that different surface texture treatment methods can alter the hardness of the tube surface with significant influence on the tribological performance.
A Long-Period, Violently Variable X-ray Source in a Young Supernova Remnant
Authors: De Luca A. , Caraveo P. A. , Mereghetti S. , Tiengo A. , Bignami G. F.
Published: July 2006

Observations with the Newton X-ray Multimirror Mission satellite show a strong periodic modulation at 6.67 ± 0.03 hours of the x-ray source at the center of the 2000-year-old supernova remnant RCW 103. No fast pulsations are visible. If genetically tied to the supernova remnant, the source could either be an x-ray binary, composed of a compact object and a low-mass star in an eccentric orbit, or an isolated neutron star. In the latter case, the combination of its age and period would indicate that it is a peculiar magnetar, dramatically slowed down, possibly by a supernova debris disc. Both scenarios require nonstandard assumptions about the formation and evolution of compact objects in supernova explosions.
16S rRNA Phylogenetic Investigation of the Candidate Division “
Korarchaeota
”
Authors: Auchtung Thomas A. , Takacs-Vesbach Cristina D. , Cavanaugh Colleen M.
Published: July 2006

The environmental distribution and phylogeny of “
Korarchaeota
,” a proposed ancient archaeal division, was investigated by using the 16S rRNA gene framework.
Korarchaeota
-specific primers were designed based on previously published sequences and used to screen a variety of environments.
Korarchaeota
16S rRNA genes were amplified exclusively from high temperature Yellowstone National Park hot springs and a 9°N East Pacific Rise deep-sea hydrothermal vent. Phylogenetic analyses of these and all available sequences suggest that
Korarchaeota
exhibit a high level of endemicity.
Perpetuation of the Lyme Disease Spirochete
Borrelia lusitaniae
by Lizards
Authors: Richter Dania , Matuschka Franz-Rainer
Published: July 2006

To determine whether the Lyme disease spirochete
Borrelia lusitaniae
is associated with lizards, we compared the prevalence and genospecies of spirochetes present in rodent- and lizard-associated ticks at a site where this spirochete frequently infects questing ticks. Whereas questing nymphal
Ixodes ricinus
ticks were infected mainly by
Borrelia afzelii
, one-half of the infected adult ticks harbored
B. lusitaniae
at our study site. Lyme disease spirochetes were more prevalent in sand lizards (
Lacerta agilis
) and common wall lizards (
Podarcis muralis
) than in small rodents. Although subadult ticks feeding on rodents acquired mainly
B. afzelii
, subadult ticks feeding on lizards became infected by
B. lusitaniae
. Genetic analysis confirmed that the spirochetes isolated from ticks feeding on lizards are members of the
B. lusitaniae
genospecies and resemble type strain PotiB2. At our central European study site, lizards, which were previously considered zooprophylactic for the agent of Lyme disease, appear to perpetuate
B. lusitaniae
.
Diversity of Microcystin-Producing Cyanobacteria in Spatially Isolated Regions of Lake Erie
Authors: Rinta-Kanto Johanna M. , Wilhelm Steven W.
Published: July 2006

The diversity of microcystin-producing cyanobacteria in the western basin of Lake Erie was studied using sequence analysis of
mcyA
gene fragments. Distinct populations of potentially toxic
Microcystis
and
Planktothrix
were found in spatially isolated locations. This study highlights previously undocumented diversity of potentially toxic cyanobacteria.
Infection Paradox: High Abundance but Low Impact of Freshwater Benthic Viruses
Authors: Filippini Manuela , Buesing Nanna , Bettarel Yvan , Sime-Ngando Télesphore , Gessner Mark O.
Published: July 2006

The discovery of an abundant and diverse virus community in oceans and lakes has profoundly reshaped ideas about global carbon and nutrient fluxes, food web dynamics, and maintenance of microbial biodiversity. These roles are exerted through massive viral impact on the population dynamics of heterotrophic bacterioplankton and primary producers. We took advantage of a shallow wetland system with contrasting microhabitats in close proximity to demonstrate that in marked contrast to pelagic systems, viral infection, determined directly by transmission electron microscopy, and consequently mortality of prokaryotes were surprisingly low in benthic habitats in all seasons. This was true even though free viruses were abundant throughout the year and bacterial infection and mortality rates were high in surrounding water. The habitats in which we found this pattern include sediment, decomposing plant litter, and biofilms on aquatic vegetation. Overall, we detected viruses in only 4 of a total of ∼15,000 bacterial cells inspected in these three habitats; for comparison, nearly 300 of ∼5,000 cells suspended in the water column were infected. The strikingly low incidence of impact of phages in the benthos may have important implications, since a major portion of microbial biodiversity and global carbon and nutrient turnover are associated with surfaces. Therefore, if failure to infect benthic bacteria is a widespread phenomenon, then the global role of viruses in controlling microbial diversity, food web dynamics, and biogeochemical cycles would be greatly diminished compared to predictions based on data from planktonic environments.
Sequence Diversity of theBacillus thuringiensisandB. cereusSensu Lato Flagellin (H Antigen) Protein: Comparison with H Serotype Diversity
Authors: Xu Dong , Côté Jean-Charles
Published: July 2006

We set out to analyze the sequence diversity of theBacillus thuringiensisflagellin (H antigen [Hag]) protein and compare it with H serotype diversity. Some otherBacillus cereussensu lato species and strains were added for comparison. The internal sequences of the flagellin (hag) alleles from 80Bacillus thuringiensisstrains and 16 strains from theB. cereussensu lato group were amplified and cloned, and their nucleotide sequences were determined and translated into amino acids. The flagellin allele nucleotide sequences for 10 additional strains were retrieved from GenBank for a total of 106Bacillusspecies and strains used in this study. These included 82B. thuringiensisstrains from 67 H serotypes, 5B. cereusstrains, 3Bacillus anthracisstrains, 3Bacillus mycoidesstrains, 11Bacillus weihenstephanensisstrains, 1Bacillus haloduransstrain, and 1Bacillus subtilisstrain. The first 111 and the last 66 amino acids were conserved. They were referred to as the C1 and C2 regions, respectively. The central region, however, was highly variable and is referred to as the V region. Two bootstrapped neighbor-joining trees were generated: a first one from the alignment of the translated amino acid sequences of the amplified internal sequences of thehagalleles and a second one from the alignment of the V region amino acid sequences, respectively. Of the eight clusters revealed in the tree inferred from the entire C1-V-C2 region amino acid sequences, seven were present in corresponding clusters in the tree inferred from the V region amino acid sequences. With regard toB. thuringiensis, in most cases, different serovars had different flagellin amino acid sequences, as might have been expected. Surprisingly, however, some differentB. thuringiensisserovars shared identical flagellin amino acid sequences. Likewise, serovars from the same H serotypes were most often found clustered together, with exceptions. Indeed, some serovars from the same H serotype carried flagellins with sufficiently different amino acid sequences as to be located on distant clusters. Species-wise,B. halodurans,B. subtilis, andB. anthracisformed specific branches, whereas the other four species, all in theB. cereussensu lato group,B. mycoides,B. weihenstephanensis,B. cereus, andB. thuringiensis, did not form four specific clusters as might have been expected. Rather, strains from any of these four species were placed side by side with strains from the other species. In theB. cereussensu lato group,B. anthracisexcepted, the distribution of strains was not species specific.