bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of parameters for an upsetting‐sliding test to identify friction coefficients in real contact conditions
Authors: Dubois A. , Oudin J.
Published: July 2006

The upsetting‐sliding test where a rigid contact tool induces localised plastic deformation on the surface of a test piece was developed to identify the friction coefficients and lubrication failures encountered in metal‐forming processes. The test has two consecutive stages. In the first, upsetting phase, the contact tool comes into contact with the workpiece and makes an indentation of some hundredths of a millimetre. In the second, sliding phase, the contact tool slides along the workpiece surface.

A methodology, based on mechanical analysis of this test using the finite element method, was devised to determine the parameters needed to simulate pre‐defined mechanical magnitudes at the contact tool/workpiece interface during the sliding phase. The present work shows that applying this methodology to the upsetting phase of the test reduces the number of numerical simulations required and, consequently, the cost of such a determination, whilst maintaining the test's high level of representativeness.
Multisensor monitoring of gear tooth fatigue for predictive diagnostics
Authors: Gordon Grant A. , Moose Clark A.
Published: July 2006

Successful machinery diagnostics depends on the collection and processing of prognostic features that relate back to failure precursors. Since gear teeth are a critical element in drive‐train systems, single gear tooth failure has been examined, and the identification of new prognostic features explored. A special jig was employed to orient and constrain gear samples while Hertzian loading was applied along a single contact line on the gear tooth face. This set‐up simulates the loading conditions experienced by a single tooth during gear train operation. Optical, ultrasonic, and mechanical sensors measured a variety of observables while the gear fatigue testing was under way. After monitoring the fatigue test with these three non‐commensurate sensors, data features were related to crack growth phenomena. Data collection, analysis, and interpretation are discussed for spur gear samples that show both the absence and presence of cracks and support the validity of the identified features as failure precursors. The results demonstrate the potential for using non‐traditional sensors and techniques for an in situ monitoring system.
Detecting gear tooth fatigue cracks in advance of complete fracture
Authors: Zakrajsek James J. , Lewicki David G.
Published: July 2006

Some results from using vibration‐based methods to detect gear tooth fatigue cracks are presented. An experimental test rig was used to fail a number of spur‐gear specimens through bending fatigue. The gear tooth fatigue crack in each test was initiated through a small notch in the fillet area of a tooth on the gear. The primary purpose of these tests was to verify analytical predictions of fatigue crack propagation direction and rate as a function of gear rim thickness. The vibration signal from a total of three tests was monitored and recorded for gear fault detection research. The damage consisted of complete rim fracture on the two thin rim gears and single tooth fracture on the standard full rim test gear. Vibration‐based fault detection methods were applied to the vibration signal both on‐line and after the tests were completed. The objectives of this were to identify methods capable of detecting the fatigue crack, and determine how far in advance of total failure positive detection was given. Results showed that the fault detection methods failed to respond to the fatigue crack prior to complete rim fracture in the thin rim gear tests. In the standard full rim gear test all of the methods responded to the fatigue crack in advance of tooth fracture; however, only three of the methods responded to the fatigue crack in the early stages of crack propagation.
Micro‐slip test equipment for point contacts
Authors: Hagman Lars A.
Published: July 2006

Micro‐slip can be characterised as local slip in a contact. Test equipment has been developed to study the phenomenon in point contacts. Although the equipment is designed for any point contact, the surface configuration presented here is a sphere against a flat. With the equipment, it is possible to measure accurately forces and displacements in both the normal and the tangential direction of the contact. Three‐dimensional surface topography measurements of the contact surfaces can also be made before and after each test.

A series of experiments has been carried out in which normal load, surface roughness, material combination, and lubrication were varied. The general experience gathered from the tests was that the equipment is accurate enough for very small contacts and is easy to use. The test results presented in this paper show tangential and normal displacement and tangential load for contacts subjected to small macro displacements, both undirectional and oscillating. The degree of plastic deformation in a contact is also shown for some tests.
A new electronic viscometer based on Rayleigh wave mechanics
Authors: Kauzlarich James J. , Ross Robert A. , Abdallah D. Sharif
Published: July 2006

The operation of a new viscometer is described, based on Rayleigh wave mechanics, where a thin walled tube of 5 mm diameter is immersed to a fixed depth of 60 mm in a fluid and is made to undergo axial vibrations generated by a vibrating piezoelectric plate which supports the tube. The motion of the tube is damped by the fluid, and the piezoelectric crystal feedback circuit gives a voltage inversely proportional to the square root of the viscosity × density product. The design and performance characteristics of the patented viscometer are described.

The instrument is portable and gives a measurement of viscosity × density for a test time of 1 min, over a wide range of values, and can be modified to permit continuous measurements as a function of time. The results are accurate for a Newtonian fluid, while giving an apparent viscosity × density at low shear rate for non‐Newtonian fluids. A probe measures the fluid temperature during the test. Only a small amount of fluid is necessary for measurement. Rayleigh wave mechanics theory is shown to be obeyed by the instrument.

The electronic circuit uses a phase‐locked loop to drive the thin walled tube at a resonance of about 1.5 kHz. The processor feedback signal is large, varying from 2 V down to ∼0.5 V DC when measuring SAE 10 to 60 engine oils. There is an onboard computer to process the data. The computer gives a prediction of viscosity at 40 °C, or can be modified to predict viscosity at any reference temperature, for a paraffinic or a naphthenic mineral oil, as well as for various synthetic oils. For a particular fluid, it is possible to build data reduction into the computer, for example, equations for density as a function of temperature can be stored in the computer to reduce the viscosity × density result to viscosity and to density.
Sync‐period frequency analysis and its application to the diagnosis of multiple element defects of rolling bearings
Authors: Wen‐Yi Wang , Harrap Michael J.
Published: July 2006

A method for diagnosing multiple element defects in rolling bearings has been investigated. The method combines the time‐synchronous averaging and envelope spectral analysis techniques to produce spectra of synchronously averaged envelope signals with a range of synchronous frequencies. The spectra are displayed in the synchronous period versus frequency domain, to result in the sync‐period versus frequency distribution. The distribution separates the characteristic defect frequencies and their associated sidebands in the synchronous period axis. This analysis technique makes it possible to detect and diagnose multiple defects appearing in different elements of rolling bearings. Another main benefit of the method is the significant noise reduction by both the enveloping and the synchronous averaging processes. Results from both computer synthesised data and experimental simulated data are presented.
Development of a new type of corrosive wear tester
Authors: Yanliang Huang , Baorong Hou , Xiaoxia Jiang , Shizuo Li
Published: July 2006

A new type of corrosive wear tester has been developed, on which both static and transient corrosive wear tests can be performed. By combining the tester with an electrochemical measuring system and a dynamic strain gauge, studies can be done in fields such as polarisation curve measurement under conditions of corrosive wear, surface state and wear coefficient measurement, and dynamic observations of current under static potential, as well as the study of surface film rupture and recovery. Leakage of the solution was considered throughout the design, and was addressed by avoiding passing the rotating shaft through the electrolytic cell.
Some aspects of rolling friction resistance in a complex tribological pair – the bicycle wheel bearing
Authors: Styp‐Rekowski Michat
Published: July 2006

Bicycles are an important means of transport — over 20 million are manufactured worldwide each year, and, because their source of motive energy is human, their energy conversion, as measured by their resistance to motion, is critical. The bearings used in bicycles are rolling bearings, but are normally of different materials and construction quality to the roller bearings used in other applications.

The present paper is intended to provide an indication of the phenomena influencing the resistance to motion and loss of energy of these bearings, and is based on a rolling bearing test stand designed by the author. A mathematical model derived from experimental observation is presented, and the theoretical results compared with experimental results.
A scuffing load capacity test with the FZG gear test rig for gear lubricants with high EP performance
Authors: Höhn B.‐R. , Michaelis K. , Eberspächer C. , Schlenk L.
Published: July 2006

Methods for the evaluation of the scuffing load capacity of EP lubricants of API GL‐4 and GL‐5 performance levels have been developed for the standard FZG gear test rig, which has a centre distance of a = 91.5 mm. Procedure A10/16.6R/90 is capable of discriminating between industrial gear oils and automotive gear oils up to GL‐4 performance level while procedure S‐A10/16.6R/90 can be applied to GL‐4 and GL‐5 lubricants. The test methods were verified with reference oils and commercial gear lubricants. The results of the tests can be used to give a relative ranking of reference and candidate lubricants. They can also be used as limiting values in the scuffing load capacity rating method according to DIN 3990 (ISO DIS 6336).
A new electrochemical technique to study tribocorrosion at the micrometric scale
Authors: Assi F. , Suter T. , Böhni H.
Published: July 2006

A new method to investigate the tribocorrosion properties of metals and alloys has been developed with which the current density of a metal probe in an electrolyte under rubbing conditions can be measured. The electrochemical microcell consists of a microcapillary (inner diameter 0.84 mm); the rubbing partner is an Al2O3 tube which rotates inside the microcapillary. Rotational speed, load and applied electrical potential can be varied, so that it is possible to analyse the corrosion rate during rubbing under various controlled conditions.

With conventional tribocorrosion machines (e.g., pin‐on‐disc, ball‐on‐plate rig) and also with single‐scratch test machines, the current measured also derives from surface areas which are not undergoing mechanical wear. In the present method, the activation of specific surface areas under rubbing conditions, and subsequent repassivation, can be studied separately.
A review of condition monitoring and fault diagnosis for diesel engines
Authors: Jones N. B. , Li Yu‐Hua
Published: July 2006

Technical advances and environmental legislation in recent years have stimulated the development of a number of techniques for condition monitoring and fault diagnosis (CMFD) in diesel engines. This paper firstly summarises common faults, fault mechanisms and their effect on diesel engine performance. Corresponding measurands are presented. Standard CMFD methods for parameters and CMFD systems for diesel engines are reviewed. Finally, some advanced CMFD techniques, including neural networks and fuzzy logic, which may be more powerful, are discussed.
Method for scuffing propagation assessment
Authors: Piekoszezuski W. , Szczerek M. , Tuszynski W.
Published: July 2006

This paper describes a method for the determination of scuffing propagation using a four‐ball extreme‐pressure tester. The method has been developed at the authors' laboratory and is a completely new approach to the investigation of scuffing phenomena. A series of lubricants was prepared by blending antiwear (AW) and extreme‐pressure (EP) additives with a mineral base oil. Tribological experiments were then performed using the new method. The aim was to investigate the influence of such additives on scuffing propagation. It is shown that there is a significant influence of AW and EP additives on scuffing. Surface analyses (SEM, EDS) show the decisive role of the chemical reactions of AW and EP additives with the steel surface and their creation of a surface layer whose good antiseizure properties mitigate scuffing propagation and reduce wear intensity. It must be emphasised that the authors consider scuffing to be a process leading to the cessation of the relative movement of a tribosystem, known as seizure.
Phenomenological investigation of cutting oils: Antifriction and antiwear behaviour at low contact temperatures
Authors: Pandazaras C. N. , Ivkovic B. , Petropoulos G. P.
Published: July 2006

The basic reason for the use of cutting fluids in machining processes is to increase cutting tool life and to decrease machining costs. An experimental simulation of tribological processes representing rear cutting tool contact was carried out in a ‘block‐on‐disc’ (BOD) tribotester. The coefficient of friction and block wear were measured under boundary (discontinuous fluid film) and elastohydrodynamic (quasi‐continuous fluid film) lubrication conditions for neat and semi‐synthetic cutting oils. Interesting data were obtained concerning a further cutting fluid classification, which is helpful for optimal cutting fluid selection via their antiwear and antifriction characteristics.
Effect of temperature on the scuffing load capacity of EP gear lubricants
Authors: Hölm B.‐R. , Miclwelis K. , Collenberg H. , Schlenk L.
Published: July 2006

Scuffing of gears involves the welding together of locally unprotected metal‐to‐metal contacts when critical limits of pressure and temperature are exceeded. Protection can be maintained by a thick lubricant film, by physically adsorbed layers, or by chemical reaction layers. At higher temperatures, viscosity and film thickness decrease but, using an EP gear oil, due to higher chemical reactivity, the scuffing load capacity is not necessarily reduced accordingly. The reaction temperature of the additives is not always reached for large gears. In this paper the factors that influence the scuffing load capacity are investigated, and test possibilities and calculation methods are outlined.
Statistical study of organomolybdenum compounds in an engine oil formulation and the results of engine testing
Authors: Saini M. S. , Lockwood F. E. , Smith T. R. , Pridemore D. , Grulke E. A.
Published: July 2006

Organomolybdenum compounds are versatile lubricant additives of interest in the design of engine oils to meet the new ILSAC (International Lubricant Standardization and Approval Committee) GF‐3 performance standard, especially for fuel efficiency. In this work, organomolybdenum and 13 other components were studied by experimental design and statistical analysis to determine their effects on friction, wear, and oxidation properties. The resulting linear model was used to construct a trial engine oil formulation. Engine test results, including some new tests required for ILSAC GF‐3, confirmed some of the strengths of organomolybdenum compounds, as well as their sensitivity to other additives in the formulation.
The results of ferrography tests and their evaluation
Authors: Stodola Jiří
Published: July 2006

This paper discusses ways of applying mathematical methods to evaluate the results of tribodiagnostics (ferrography) related to vehicle engines. The idea is based on a discriminative analysis which makes it possible to describe one qualitative parameter, e.g., the complex technical state of the engine, by means of several quantitative parameters, e.g., the quantity of diagnosed wear particles in used oil. The results have been verified using statistical data from truck and automobile engines.
Preparation and evaluation of vegetable oil derived biodiesel esters as lubricity additives
Authors: Lang X. , Dalai A. K. , Reaney M. J. , Hertz P. B.
Published: July 2006

Various vegetable‐oil derived esters using methyl, ethyl, butyl, and 2‐propyl alcohols were prepared and tested as diesel fuel lubricity additives in a roller‐on‐cylinder lubricity evaluator. At1% additive treat rate, the canola methyl and 2‐propyl esters, the best‐performing esters, increased the lubricity number of a reference fuel by 60%. Statistical analyses indicated strong effects of fatty acids and alcohols on the wear, friction, and lubricity number of the fuel. While no single fatty acid was identifiably responsible for the wear reduction, certain non‐linoleic compounds correlated with the wear data in a semi‐log relationship. The low‐temperature behaviour of the biodiesel was studied using differential scanning calorimetry. The major transitional peak temperature of the biodiesel esters changed with the melting points of their primary fatty acids, and decreased with the lengthening and branching of the tail alkyl groups.
A method for testing lubricants under conditions of scuffing. Part I. Presentation of the method
Authors: Szczerek M. , Tuszynski W.
Published: July 2006

A method for the tribological assessment of lubricants under conditions of scuffing is presented. The method uses a four‐ball tester, and allows one to assess the effect of lubricant on scuffing intensity through an analysis of changes in the friction torque and wear of the stationary balls, at continuously increasing load. The behaviour of a lubricant under scuffing conditions can be characterised using the so‐called limiting pressure of seizure poz, which depends on the load at which the balls seize and the average value of the wear area calculated from the wear‐scar diameters measured on the stationary balls.

A comparison is made ‐ from the point of view of the resolution, time consumption, and cost ‐ of the new method with the existing, standard tests, using a four‐ball tester and a gear test rig (FZG). It is concluded that the proposed method, unlike standard FZG and certain four‐ball tests, enables one to differentiate between gear oils, in agreement with their API GL performance level. The very short run‐time of the new method enables one to perform more tests and obtain a low standard deviation. The new method is much cheaper than the standard four‐ball and FZG methods.
Investigation of hard lubricant coatings in space in orbit around the moon
Authors: Yarosh V. M. , Moisheev A. A. , Bronovets M. A.
Published: July 2006

This paper reports on friction tests of a hard lubricant coating conducted in orbit around the Moon. The measurements included those taken in terrestrial conditions in a vacuum chamber, at the launch site, and in lunar orbit. The paper includes a description of an autonomous friction simulator that was mounted outside the spacecraft. In this device, two types of friction, ‘shaft‐bush’ and ‘disc‐indenter’, have been tested. For the first time, a long experiment exploring the tribological characteristics of an antifriction coating in a real space environment in a lunar satellite orbit has been carried out. Over a fifteen‐month period, the friction units were run in the space environment. These tests indicated a tendency for the friction coefficient to reduce to a limit value in such an orbit and environment.
Laboratory evaluation of anti‐fretting lubricants
Authors: Hargreaves Doug , Singerling B. F. , Pai R.
Published: July 2006

To characterise the friction and wear behaviour of materials and lubricants under a variety of operating conditions, laboratory models are frequently used to provide useful information. For example, during the development and/or selection of tribomaterials and lubricants, laboratory ranking of candidate products can save many hours of field testing. A reciprocating ball‐on‐flat wear test rig has been developed to rank the performance of materials, surface coatings, and lubricants under boundary, extreme‐pressure, or fretting conditions in a variety of environments and at various temperatures. The rig design is based on ASTM G133–1995. The friction force and wear are measured on both specimens while the load, stroke length and frequency, test temperature, lubricant type, test duration, surface topography of both ball and flat specimens, specimen materials, and environmental conditions are noted.

The results presented in this paper refer specifically to a series of tests performed to evaluate various anti‐fretting lubricants. Two lubricants are compared in terms of friction coefficient and wear volume over time. A clear difference is shown between the two products.
Calculation of sliding power loss in spur gear contacts
Authors: Lehtovaara Arto
Published: July 2006

An engineering‐level calculation model for sliding power loss in spur gear contacts is presented. Teeth contact through the line of action is modelled as a constantly changing roller contact whose radius, speed, and load can be calculated from the gear geometry under the given operating conditions. The gear mesh cycle is approximated by a large number of elastohydrodynamic contacts. A constant film thickness and a Hertzian pressure distribution are assumed in each contact. The model includes non‐Newtonian lubricant behaviour together with temperature and mixed lubrication effects in contact. The numerical solver is reasonably fast in evaluating effectively the sliding power loss dependence on the essential gear and lubricant parameters. The features and behaviour trends of the calculated sliding power losses have a close similarity with published results obtained from measurements and experiment‐based power loss models with mineral oil. The limiting shear stress of the lubricant is observed to have an essential role in the power loss behaviour especially at high loads.
Experimental evaluation of the stress distribution on the outer surface of the outer race of conventional and double‐decker high‐precision bearings
Authors: Prashad Har
Published: July 2006

Experimental investigations have been carried out on the stress distribution on the outer surface of the outer race of conventional and double‐decker high‐precision bearings (DDHPBs). The investigations, in general, indicate that the overall level of stress variation on conventional bearings in various modes of loading under static conditions is greater than that of DDHPBs having an identical inner bore. The cyclic stress levels have been found to be higher for the outer race of conventional bearings compared to that of DDHPBs. Also, the frequency of stress cycles on the outer race of conventional bearings is greater than that of DDHPBs.

A comparison of the stress distribution pattern indicates that, under identical loads, the ratio of deflection to indentation on the elements of DDHPBs and conventional bearings is less than unity. Also, under identical operating conditions, the ratio of stresses due to centrifugal forces on the elements of DDHPBs and conventional bearings of the same bore and outer diameter is less than unity. It is concluded that the life of DDHPBs as compared to conventional bearings should be longer under identical operating conditions.
Scheduling with base station diversity and fairness analysis for the downlink of CDMA cellular networks
Authors: Dianati Mehrdad , Shen Xuemin (Sherman) , Naik Kshirasagar
Published: July 2006

Efficient packet scheduling in CDMA cellular networks is a challenging problem due to the time variant and stochastic nature of the channel fading process. Selection diversity is one of the most effective techniques utilizing random and independent variations of diverse channels to improve the performance of communication over fading channels. In this paper, we propose two packet scheduling schemes exploiting base station selection diversity in the downlink of CDMA cellular networks. The proposed schemes rely on the limited instantaneous channel state information (CSI) to select the best user from the best serving base station at each time slot. This technique increases the system throughput by increasing multiuser diversity gain and reducing the effective interference among adjacent base stations. Results of Monte Carlo simulations are given to demonstrate the improvement of system throughput using the proposed scheduling schemes. In addition, we investigate fairness issue of wireless scheduling schemes. Due to different characteristics of wireless scheduling schemes, the existing fairness indexes may result in misleading comparison among different schemes. We propose a new fairness index to compare the overall satisfaction of the network users for different scheduling schemes. Copyright © 2006 John Wiley & Sons, Ltd.
First experiences with free‐ranging giant day geckos (Phelsuma madagascariensis grandis, Gray 1870) in the masoala rainforest exhibit in Zurich Zoo, Switzerland
Authors: Furrer Samuel C. , Jaag Kathrin , von Stockar Sabine , Rübel Alex
Published: July 2006

Sixty giant day geckos (Phelsuma madagascariensis grandis) have been introduced into the Masoala rainforest exhibit of Zurich Zoo. Eighteen geckos were monitored during a 3‐month study using the telemetry method. In general, the geckos were able to adapt well under these semi‐natural conditions of the exhibit. The geckos accessed to nearly all locations in the exhibit; some of the animals remained stationary, whereas others covered dozens of meters within a week. They preferred four species of plants as well as the artificial structures supporting the walls and roof of the exhibit, and displayed natural behaviors. Animals were observed feeding on all kind of arthropods and nectar substances, and also on food items dropped from feeding stations for other species. Deliberate feeding targeted at the geckos was finally reduced to a calcium‐rich squash along the visitor's main path. Reproduction was observed frequently within the exhibit. These findings suggest that the geckos will be able to build up a self‐sustaining population and contribute to a nearly‐authentic experience for zoo visitors. Zoo Biol 0:1–7, 2006. © 2006 Wiley‐Liss, Inc.
Identification of Patients at Low Risk for Thyroidectomy‐Related Hypocalcemia by Intraoperative Quick PTH
Authors: Fabio Francesco Di , Casella Claudio , Bugari Giovanna , Iacobello Carmelo , Salerni Bruno
Published: July 2006

Background

Transient hypoparathyroidism is a frequent and challenging complication following total thyroidectomy. The aim of the study was to identify patients at risk of developing thyroidectomy‐related hypocalcemia and symptoms by means of the intraoperative quick parathyroid hormone (PTH) assay.

Methods

Eighty‐one patients undergoing total thyroidectomy were included in the study. Quick PTH levels were measured at induction of anaesthesia and 10 minutes after total thyroidectomy. A sample of 10 patients who underwent unilateral thyroid lobectomy was considered as a control group. The accuracy of intraoperative PTH decline in predicting postoperative hypoparathyroidism was analysed.

Results

After total thyroidectomy, 27 patients (33.3%) developed postoperative hypocalcemia. Symptoms were reported by 21 patients (25.9%). The mean percentage decline of intraoperative quick PTH was 81% in hypocalcemic compared with 39% in normocalcemic patients (P < 0.001), and it was 83% in symptomatic compared with 42% in asymptomatic patients (P < 0.001). Mean proportion decline of quick PTH after unilateral lobectomy was 20%, significantly lower than the 53% registered after total thyroidectomy (P = 0.005). Analysis of variation of intraoperative quick PTH with the receiver operator characteristics (ROC) curve showed a 75.7% decline as the cut‐off value predicting postoperative hypocalcemia with the highest accuracy (91.4%) (sensitivity: 81.5% specificity: 96.3% positive likelihood ratio: 22; negative likelihood ratio: 0.2). Regarding the prediction of postoperative symptoms, a 79.5% decline was the most accurate (92.6%) cut‐off point (sensitivity: 76.2% specificity: 98.3% positive likelihood ratio: 46; negative likelihood ratio: 0.2).

Conclusions

Quick PTH monitoring during total thyroidectomy is a useful means for identifying low‐risk patients for postoperative hypoparathyroidism and candidates for early, safe discharge. Furthermore, it is an objective method complementary to the surgeon’s judgement of the intraoperative function of parathyroid glands, which should be implanted in the event of a 75%–80% decline.
Adolescents’ views of helping professionals: A review of the literature
Authors: Freake Helen , Barley Val , Kent Gerry
Published: July 2006

This paper reviews 54 papers exploring adolescents’ own views of their interactions with doctors, mental health workers and other ‘helping professionals’. Twelve global themes emerge repeatedly in the qualitative literature, where adolescents are asked to talk about their preferences or their experiences of receiving help from such professionals. The twelve themes are reported and illustrated with results of related quantitative studies, and implications of these themes for professionals offering services to this age group are considered. Methodological limitations of the literature are discussed, along with suggestions for future research.
Effect of thoracoscopic splanchnic denervation on pain processing in chronic pancreatitis patients
Authors: Buscher H.C.J.L. , van Goor H. , Wilder‐Smith O.H.G.
Published: July 2006

Background: Central sensitisation due to visceral pancreatic nociceptive input may play an important role in chronic pancreatitis pain. Using quantitative sensory testing (QST), this first study investigates whether thoracoscopic splanchnic denervation (TSD), performed to reduce nociceptive visceral input, affects central sensitisation in chronic pancreatitis patients.

Patients and methods: We studied 19 chronic pancreatitis patients (11 men, 8 women on stable opioid medication) and 18 healthy volunteers as preoperative controls. Preoperatively and 6 weeks after TSD, pain numeric rating scores, opioid medication, and thresholds to electric skin stimulation and pressure pain (measured in dermatomes T10 (pancreas), C5, T4, L1, L4) were documented. Treatment success was defined as cessation of opioids 6 weeks after TSD.

Results: Six weeks after TSD, there was a trend towards lower pain scores, only 10 patients were still on opioids (P<0.05 vs. preoperatively) and thresholds overall were significantly higher than preoperatively (pressure pain: +25%, P<0.001; electric: sensation +55%, pain detection +34%, pain tolerance +21%, P<0.05). Gender‐specific differences in hypoalgesia patterns were seen. Preoperatively, TSD treatment successes consumed significantly less opioids than failures, without significant differences in preoperative patterns of neuroplasticity.

Conclusions: TSD for chronic pancreatitis pain resulted in fewer patients on opioids and overall increases in pain thresholds. Our results suggest that TSD for reducing visceral nociceptive input may be effective in reducing resulting central sensitisation. Although patients benefiting from TSD consume less opioids preoperatively, we were unable to clearly link treatment success with specific perioperative patterns of neuroplasticity such as the presence or absence of hyperalgesia.
Expression and functional characterization of ABCG1 splice variant ABCG1(666)
Authors: Engel Thomas , Bode Guenther , Lueken Aloys , Knop Markus , Kannenberg Frank , Nofer Jerzy-Roch , Assmann Gerd , Seedorf Udo
Published: July 2006

The ATP‐binding cassette transporter ABCG1 mediates the transport of excess cholesterol from macrophages and other cell types to high density lipoprotein (HDL) but not to lipid‐depleted apolipoprotein AI. Several splice variants which may have different functions have been identified in mammals. In the current study, we characterized the human splice variant ABCG1(666), which differs from full‐length ABCG1(678) by absence of an internal segment of 12 amino acids (VKQTKRLKGLRK). Accordingly spliced ABCG1 transcripts were detected in macrophages and liver in approximately twofold higher amounts than the alternatively spliced ABCG1 form encoding full‐length ABCG1. We used transient and stable expression of ABCG1(666) fusion proteins to characterize glycosylation, subcellular localization, molecular interaction and functions of this ABCG1 variant. It could be demonstrated that ABCG1(666) is located at the cell surface and has the ability to form cholesterol transport competent homodimers which affect cellular cholesterol export in a similar manner as previously characterized forms of ABCG1. Our results support that ABCG1(666) may in fact be the most prominent form of functional ABCG1 expressed in the human.
Postglacial vegetation, climate, and fire history along the east side of the Andes (lat 41–42.5°S), Argentina
Authors: Whitlock Cathy , Bianchi Maria Martha , Bartlein Patrick J. , Markgraf Vera , Marlon Jennifer , Walsh Megan , McCoy Neil
Published: July 2006

The history of the low-elevation forest and forest-steppe ecotone on the east side of the Andes is revealed in pollen and charcoal records obtained from mid-latitude lakes. Prior to 15,000 cal yr BP, the vegetation was characterized by steppe vegetation with isolated stands of Nothofagus. The climate was generally dry, and the sparse vegetation apparently lacked sufficient fuels to burn extensively. After 15,000 cal yr BP, a mixture of Nothofagus forest and shrubland/steppe developed. Fire activity increased between 13,250 and 11,400 cal yr BP, contemporaneous with a regionally defined cold dry period (Huelmo/Mascardi Cold Reversal). The early-Holocene period was characterized by an open Nothofagus forest/shrubland mosaic, and fire frequency was high in dry sites and low in wet sites; the data suggest a sharp decrease in moisture eastward from the Andes. A shift to a surface-fire regime occurred at 7500 cal yr BP at the wet site and at 4400 cal yr BP at the dry site, preceding the expansion of Austrocedrus by 1000–1500 yr. The spread of Austrocedrus is explained by a shift towards a cooler and wetter climate in the middle and late Holocene. The change to a surface-fire regime is consistent with increased interannual climate variability and the onset or strengthening of ENSO. The present-day mixed forest dominated by Nothofagus and Austrocedrus was established in the last few millennia.
Community-associated methicillin-resistant Staphylococcus aureus skin infections in a religious community
Authors: CORONADO F. , NICHOLAS J. A. , WALLACE B. J. , KOHLERSCHMIDT D. J. , MUSSER K. , SCHOONMAKER-BOPP D. J. , ZIMMERMAN S. M. , BOLLER A. R. , JERNIGAN D. B. , KACICA M. A.
Published: July 2006

In September 2004, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTI) was reported among members of a religious community. We conducted a retrospective cohort study on all 175 community members; performed a nasal carriage survey, and environmental swab testing. We identified 24 MRSA cases (attack rate 14%). In multivariate analysis, sauna use [odds ratio (OR) 19·1, 95% confidence interval (CI) 2·7–206·1] and antimicrobial use within 12 months before infection (OR 11·7, 95% CI 2·9–47·6) were risk factors for infection. MRSA nasal carriage rate was 0·6% (1/174). Nine of 10 clinical isolates and an isolate from an administrative office within the community had the pulsed-field gel electrophoresis type USA300. Targeted hygiene improvement, wound care, and environmental cleaning were implemented. We describe the first reported outbreak of MRSA SSTI in a religious community. Adherence to appropriate personal and environmental hygiene might be critical factors in controlling transmission.
Estimation of the long‐term variability of extreme significant wave height using a time‐dependent Peak Over Threshold (POT) model
Authors: Méndez Fernando J. , Menéndez Melisa , Luceño Alberto , Losada Inigo J.
Published: July 2006

Recent evidence suggests long‐term changes in the intensity and frequency of extreme wave climate around the globe. These changes may be attributable to global warming as well as to the natural climate variability. A statistical model to estimate long‐term trends in the frequency and intensity of severe storm waves is presented in this paper. The model is based on a time‐dependent version of the Peak Over Threshold model and is applied to the Washington NOAA buoy (46005) significant wave height data set. The model allows consideration of the annual cycle, trends, and relationship to atmosphere‐ ocean‐related indices. For the particular data set analyzed the inclusion of seasonal variability substantially improves the correlation between the model and the data. Also, significant correlations with the Pacific–North America pattern, as well as long‐term trend, are detected. Results show that the model is appropriate for a rigorous analysis of long‐term trends and variability of extreme waves and for providing time‐dependent quantiles and confidence intervals.
Scope sensitivity in households' willingness to pay for maintained and improved water supplies in a developing world urban area: Investigating the influence of baseline supply quality and income distribution upon stated preferences in Mexico City
Authors: Soto Montes de Oca Gloria , Bateman Ian J.
Published: July 2006

We present the first assessment of willingness to pay (WTP) for water supply change to be conducted in the largest city in the developing world: Mexico City. Two large sample contingent valuation surveys are conducted to investigate WTP for two levels of water service quality: maintenance of or improvement over current provision levels. This study design permits one of the first tests of the “scope sensitivity” of WTP responses to different levels of baseline supply provision. This testing is complicated within the present case because as our study confirms, higher‐income households typically enjoy better levels of current provision, while poorer households generally endure lower current standards of water supply. We incorporate this heterogeneity of service and correlation with income within a suite of novel scope sensitivity tests. These confirm prior expectations that richer households enjoying higher baseline service levels would prefer programs to maintain the status quo, while poorer households enduring lower initial quality of service would prefer schemes which improve the quality of supplies. The implications of these findings are further investigated by contrasting conventional benefit‐cost analysis aggregation procedures with an equity weighting approach which confirms the difference in priorities according to initial supply conditions. In this case, the ranking of programs changes when the ability to pay is equalized across society. In fiscal terms, aggregate WTP figures show that authorities could collect the resources necessary to fund households' preferred schemes and simultaneously substantially reduce current subsidies.
Green‐Ampt infiltration model for sloping surfaces
Authors: Chen Li , Young Michael H.
Published: July 2006

This work quantifies and explains the direct physical effects of slope angle on infiltration and runoff generation by extending the Green‐Ampt equation onto sloping surfaces. A new extended solution using identical precipitation hydrographs was compared to the original formulation and then used to calculate the infiltration and runoff generation for different slope angles but for identical horizontal projection lengths. Homogeneous and isotropic soil is assumed, and two different boundary conditions for vertical rainfall are studied: ponded infiltration and infiltration under steady rainfall. Infiltration under unsteady rainfall was found to be similar to cases with steady rainfall. Both theoretical and numerical results show that infiltration increases with increasing slope angle. For cases with ponded infiltration the slope effect was generally not significant for mild to moderate slopes, but the slope effect became more important for low‐intensity and short‐duration rainfall events, especially as it delayed the time for ponding. It was also found that the cumulative vertical infiltration depth (Ihp) at ponding (or the initial loss) increases with increasing slope angle. The model was compared to Richards' equation on horizontal and sloping surfaces and found to perform well. The model's applicability for nonuniform slopes was discussed, and it was found that the model is generally applicable for isotropic and mildly anisotropic soils except for some small‐scale topographic elements. Finally, the occurrence of nonvertical rainfall could increase runoff with increasing slope angle when rainfall deflects a large angle to upslope.
Photoreductive dissolution of ferrihydrite by methanesulfinic acid: Evidence of a direct link between dimethylsulfide and iron‐bioavailability
Authors: Johansen Anne M. , Key Jennifer M.
Published: July 2006

Within open‐ocean regions where excess macronutrients are present, phytoplankton growth is limited by the bioavailability of iron supplied to these areas primarily within atmospheric aerosols of crustal origin. However, processes that control the abundance of biologically accessible iron in these aerosols are largely unknown. Here we show that dissolution of ferrihydrite, a surrogate iron(oxy)hydroxide phase found in atmospheric waters, is enhanced in the presence of methanesulfinic acid (MSIA, CH3SO2H, a dimethylsulfide (DMS) oxidation intermediate) in laboratory irradiation experiments with aqueous suspensions that simulate marine aerosol particles. The increased release of soluble Fe(II) is attributed to a species specific and direct photochemical reduction rather than a proton‐promoted effect, and suggests an efficient mechanism by which iron‐starved phytoplankton can actively increase aerosol iron‐bioavailability by increasing DMS emissions.
Ship‐based aerosol optical depth measurements in the Atlantic Ocean: Comparison with satellite retrievals and GOCART model
Authors: Smirnov A. , Holben B. N. , Sakerin S. M. , Kabanov D. M. , Slutsker I. , Chin M. , Diehl T. L. , Remer L. A. , Kahn R. , Ignatov A. , Liu L. , Mishchenko M. , Eck T. F. , Kucsera T. L. , Giles D. , Kopelevich O. V.
Published: July 2006

Aerosol optical depth measurements were made in October–December 2004 onboard the R/V Akademik Sergey Vavilov. The cruise area included an Atlantic transect from North Sea to Cape Town and then a crossing in the South Atlantic to Argentina. In the open oceanic areas not influenced by continental sources aerosol optical depth values were close to background oceanic conditions (τa ∼ 0.06–0.08). Spectral dependence, especially in the high latitude Southern Atlantic, can be considered as quasi‐neutral (Angstrom parameter α was less than 0.4). Back‐trajectory analysis allowed statistical division of the aerosol optical parameters and showed similar properties for the North Atlantic polar marine, South Atlantic subtropical marine and South Atlantic polar marine air. Ship‐borne aerosol optical depth comparisons to GOCART model and satellite retrievals revealed systematic biases. Satellite retrieved optical depths are generally higher by 0.02–0.07 (depending on the sensor), especially in low τa conditions. GOCART model simulated optical depths correlate well with the ship measurements and, despite overall bias and a notable disparity with the observations in a number of cases, about 30% agree within ±0.01.
GPS profiling of the lower troposphere from space: Inversion and demodulation of the open‐loop radio occultation signals
Authors: Sokolovskiy S. , Rocken C. , Hunt D. , Schreiner W. , Johnson J. , Masters D. , Esterhuizen S.
Published: July 2006

Global Positioning System (GPS) radio occultation (RO) is a space‐borne remote sensing technique providing accurate, all‐weather, high vertical resolution atmospheric parameters, including pressure, temperature and humidity in the troposphere and stratosphere. In the moist lower troposphere (LT) RO encounters known problem related to the phase‐locked loop (PLL) tracking technique applied in standard GPS receivers and the complicated structure of LT RO signals. This problem has been overcome by developing an open‐loop (OL) tracking technique. This paper outlines post‐processing of OL RO data. In order to invert OL RO signals, the GPS navigation data modulation (NDM) has to be removed in post‐processing. This paper demonstrates that some tropical occultations are not accurately inverted (associated refractivity inversion errors exceed 5%) without the use of externally supplied NDM bit sequences. This result has important implications for the use of RO data from future RO missions for climate research and weather forecasting.
Reduced Oxidative Stress Promotes NF-κB-Mediated Neuroprotective Gene Expression after Transient Focal Cerebral Ischemia: Lymphocytotrophic Cytokines and Antiapoptotic Factors
Authors: Song Yun Seon , Lee Yong-Sun , Narasimhan Purnima , Chan Pak H
Published: July 2006

Nuclear factor-kappa B (NF-κB) is activated by oxidative stress such as that induced by transient focal cerebral ischemia (tFCI). Whether NF-κB has a role in cell survival or death in stroke is a matter of debate. We proposed that the status of oxidative stress may determine its role in cell death or survival after focal ischemia. To characterize the coordinated expression of genes in NF-κB signaling after mild cerebral ischemia, we investigated the temporal profile of a NF-κB-pathway-focused DNA array after 30 mins of tFCI in wild-type (WT) mice and human copper/zinc-superoxide dismutase transgenic (SOD1 Tg) mice that had a significantly reduced level of superoxide. Differentially expressed genes among 96 NF-κB-related genes were further confirmed and compared in the WT and SOD1 Tg mice using quantitative polymerase chain reaction, Western blotting, and immunohistochemistry. Persistent upregulation of NF-κB seen at 7 days in the WT mice was decreased in the SOD1 Tg mice. Lymphocytotrophic cytokine genes such as interleukin-2, interleukin-12, and interferon-α1 were increased in the SOD1 Tg mice compared with the WT mice after tFCI. In addition, antiapoptosis factors bcl-2 and tumor necrosis factor receptor-associated factor 1 rapidly increased in the SOD1 Tg mice compared with the WT mice. This study indicates that reduced oxidative stress by SOD1 overexpression increased NF-κB-related rapid defenses, such as immune response and antiapoptosis factors, and prevented brain damage after tFCI-induced oxidative stress.