bluuebunny/crossref_metadata_2025 huggingface dataset:
Preferred and avoided codon pairs in three domains of life
Authors: Tats Age , Tenson Tanel , Remm Maido
Published: November 2008

Background

Alternative synonymous codons are not used with equal frequencies. In addition, the contexts of codons – neighboring nucleotides and neighboring codons – can have certain patterns. The codon context can influence both translational accuracy and elongation rates. However, it is not known how strong or conserved the codon context preferences in different organisms are. We analyzed 138 organisms (bacteria, archaea and eukaryotes) to find conserved patterns of codon pairs.

Results

After removing the effects of single codon usage and dipeptide biases we discovered a set of neighboring codons for which avoidances or preferences were conserved in all three domains of life. Such biased codon pairs could be divided into subtypes on the basis of the nucleotide patterns that influence the bias. The most frequently avoided type of codon pair was nnUAnn. We discovered that 95.7% of avoided nnUAnn type patterns contain out-frame UAA or UAG triplets on the sense and/or antisense strand. On average, nnUAnn codon pairs are more frequently avoided in ORFeomes than in genomes. Thus we assume that translational selection plays a major role in the avoidance of these codon pairs. Among the preferred codon pairs, nnGCnn was the major type.

Conclusion

Translational selection shapes codon pair usage in protein coding sequences by rules that are common to all three domains of life. The most frequently avoided codon pairs contain the patterns nnUAnn, nnGGnn, nnGnnC, nnCGCn, GUCCnn, CUCCnn, nnCnnA or UUCGnn. The most frequently preferred codon pairs contain the patterns nnGCnn, nnCAnn or nnUnCn.
Engineering and Applications of fungal laccases for organic synthesis
Authors: Kunamneni Adinarayana , Camarero Susana , García-Burgos Carlos , Plou Francisco J , Ballesteros Antonio , Alcalde Miguel
Published: November 2008

Laccases are multi-copper containing oxidases (EC 1.10.3.2), widely distributed in fungi, higher plants and bacteria. Laccase catalyses the oxidation of phenols, polyphenols and anilines by one-electron abstraction, with the concomitant reduction of oxygen to water in a four-electron transfer process. In the presence of small redox mediators, laccase offers a broader repertory of oxidations including non-phenolic substrates. Hence, fungal laccases are considered as ideal green catalysts of great biotechnological impact due to their few requirements (they only require air, and they produce water as the only by-product) and their broad substrate specificity, including direct bioelectrocatalysis.

Thus, laccases and/or laccase-mediator systems find potential applications in bioremediation, paper pulp bleaching, finishing of textiles, bio-fuel cells and more. Significantly, laccases can be used in organic synthesis, as they can perform exquisite transformations ranging from the oxidation of functional groups to the heteromolecular coupling for production of new antibiotics derivatives, or the catalysis of key steps in the synthesis of complex natural products. In this review, the application of fungal laccases and their engineering by rational design and directed evolution for organic synthesis purposes are discussed.
High prevalence of HIV infection among homeless and street-involved Aboriginal youth in a Canadian setting
Authors: Marshall Brandon DL , Kerr Thomas , Livingstone Chris , Li Kathy , Montaner Julio SG , Wood Evan
Published: November 2008

Aboriginal people experience a disproportionate burden of HIV infection among the adult population in Canada; however, less is known regarding the prevalence and characteristics of HIV positivity among drug-using and street-involved Aboriginal youth. We examined HIV seroprevalence and risk factors among a cohort of 529 street-involved youth in Vancouver, Canada. At baseline, 15 (2.8%) were HIV positive, of whom 7 (46.7%) were Aboriginal. Aboriginal ethnicity was a significant correlate of HIV infection (odds ratio = 2.87, 95%CI: 1.02 – 8.09). Of the HIV positive participants, 2 (28.6%) Aboriginals and 6 (75.0%) non-Aboriginals reported injection drug use; furthermore, hepatitis C co-infection was significantly less common among Aboriginal participants (p = 0.041). These findings suggest that factors other than injection drug use may promote HIV transmission among street-involved Aboriginal youth, and provide further evidence that culturally appropriate and evidence-based interventions for HIV prevention among Aboriginal young people are urgently required.
Hereditary dentine disorders: dentinogenesis imperfecta and dentine dysplasia
Authors: Barron Martin J , McDonnell Sinead T , MacKie Iain , Dixon Michael J
Published: November 2008

The hereditary dentine disorders, dentinogenesis imperfecta (DGI) and dentine dysplasia (DD), comprise a group of autosomal dominant genetic conditions characterised by abnormal dentine structure affecting either the primary or both the primary and secondary dentitions. DGI is reported to have an incidence of 1 in 6,000 to 1 in 8,000, whereas that of DD type 1 is 1 in 100,000. Clinically, the teeth are discoloured and show structural defects such as bulbous crowns and small pulp chambers radiographically. The underlying defect of mineralisation often results in shearing of the overlying enamel leaving exposed weakened dentine which is prone to wear.

Currently, three sub-types of DGI and two sub-types of DD are recognised but this categorisation may change when other causative mutations are found. DGI type I is inherited with osteogenesis imperfecta and recent genetic studies have shown that mutations in the genes encoding collagen type 1, COL1A1 and COL1A2, underlie this condition. All other forms of DGI and DD, except DD-1, appear to result from mutations in the gene encoding dentine sialophosphoprotein (DSPP), suggesting that these conditions are allelic.

Diagnosis is based on family history, pedigree construction and detailed clinical examination, while genetic diagnosis may become useful in the future once sufficient disease-causing mutations have been discovered. Differential diagnoses include hypocalcified forms of amelogenesis imperfecta, congenital erythropoietic porphyria, conditions leading to early tooth loss (Kostmann's disease, cyclic neutropenia, Chediak-Hegashi syndrome, histiocytosis X, Papillon-Lefevre syndrome), permanent teeth discolouration due to tetracyclines, Vitamin D-dependent and vitamin D-resistant rickets.

Treatment involves removal of sources of infection or pain, improvement of aesthetics and protection of the posterior teeth from wear. Beginning in infancy, treatment usually continues into adulthood with a number of options including the use of crowns, over-dentures and dental implants depending on the age of the patient and the condition of the dentition. Where diagnosis occurs early in life and treatment follows the outlined recommendations, good aesthetics and function can be obtained.
Dysphagia caused by a fibrovascular polyp: a case report
Authors: Blacha Marielle MJ , Sloots Cornelius EJ , Van Munster Ivo P , Wobbes Theo
Published: November 2008

A 73-year old man presented with dysphagia for liquid and solid food. Barium contrast study of the esophagus and esophagoscopy demonstrated a fibrovascular polyp. This, almost 10 cm benign esophageal tumor, was removed surgically by a cervical esophagotomy. A fibrovascular polyp is a rare benign tumor of the esophagus, which, however, may give serious complications as asphyxia resulting from laryngeal obstruction leading to sudden death.
Correlation between the AKI classification and outcome
Authors: Ostermann Marlies , Chang Rene ,   The Riyadh ICU Program Users Group
Published: November 2008

Introduction

The Acute Kidney Injury Network proposed a new classification for acute kidney injury (AKI) distinguishing between three stages. We applied the criteria to a large intensive care unit (ICU) population and evaluated the impact of AKI in the context of other risk factors.

Methods

Using the Riyadh Intensive Care Program database, we applied the AKI classification to 22,303 adult patients admitted to 22 ICUs in the UK and Germany between 1989 and 1999, who stayed in the ICU for 24 hours or longer and did not have end-stage dialysis dependent renal failure.

Results

Of the patients, 7898 (35.4%) fulfilled the criteria for AKI (19.1% had AKI I 3.8% had AKI II and 12.5% had AKI III). Mortality in the ICU was 10.7% in patients with no AKI, 20.1% in AKI I, 25.9% in AKI II and 49.6% in AKI III. Multivariate analysis confirmed that AKI III, but not AKI I and AKI II, were independently associated with ICU mortality (odds ratio (OR) = 2.27). Other independent risk factors for ICU mortality were age (OR = 1.03), sequential organ failure assessment (SOFA) score on admission to the ICU (OR = 1.11), pre-existing end-stage chronic health (OR = 1.65), emergency surgery (OR = 2.33), mechanical ventilation (OR = 2.83), maximum number of failed organ systems (OR = 2.80) and non-surgical admission (OR = 3.57). Cardiac surgery, AKI I and renal replacement therapy were associated with a reduced risk of dying in the ICU. AKI II was not an independent risk factor for ICU mortality. Without renal replacement therapy as a criterion, 21% of patients classified as AKI III would have been classified as AKI II or AKI I. Renal replacement therapy as a criterion for AKI III may inadvertently diminish the predictive power of the classification.

Conclusions

The proposed AKI classification correlated with ICU outcome but only AKI III was an independent risk factor for ICU mortality. The use of renal replacement therapy as a criterion for AKI III may have a confounding effect on the predictive power of the classification system as a whole.
4D volcano gravimetry
Authors: Battaglia Maurizio , Gottsmann Joachim , Carbone Daniele , Fernández José
Published: November 2008

Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the importance of this more realistic description in gravity calculations.
Gravimetric monitoring of gas production from the Troll field
Authors: Eiken Ola , Stenvold Torkjell , Zumberge Mark , Alnes Håvard , Sasagawa Glenn
Published: November 2008

Four surveys of relative gravity and depth measurements have been conducted over the Troll field since gas production began in 1996. Precision in gravity (intrasurvey repeatability measured as standard deviation) has improved from [Formula: see text] in two surveys in 2002 and 2005. The scatter of 74 station depth differences (standard deviation) has improved to [Formula: see text] (with modeled subsidence removed) for the same two surveys. Subsidence of up to [Formula: see text] is observed above the thickest reservoir of Troll East between 2002 and 2005. Time-lapse gravity shows a general slight average increase in Troll East (95% confidence for the interval centered at [Formula: see text]), which is likely caused by edgewater influx. One gravity station close to Troll A shows a [Formula: see text] gravity increase, indicating [Formula: see text] water rise. Repeated logging in a nearby well indicates [Formula: see text] rise. These two observations agree within uncertainty bounds. Gravity decrease in Troll West is explained by oil production and a downward-moving gas-oil contact. Gravity increases in two areas in the easternmost part appear statistically significant and are likely to have been caused by edgewater influx. This has not been confirmed by other data, but aquifers located near these areas make the results plausible. The gravity and subsidence data give estimates of total mass influx and pore compaction; these data have been used in and agree with material-balance calculations.
Toward continuous 4D microgravity monitoring of volcanoes
Authors: Williams-Jones Glyn , Rymer Hazel , Mauri Guillaume , Gottsmann Joachim , Poland Michael , Carbone Daniele
Published: November 2008

Four-dimensional or time-lapse microgravity monitoring has been used effectively on volcanoes for decades to characterize the changes in subsurface volcanic systems. With measurements typically lasting from a few days to weeks and then repeated a year later, the spatial resolution of theses studies is often at the expense of temporal resolution and vice versa. Continuous gravity studies with one to two instruments operating for a short period of time (weeks to months) have shown enticing evidence of very rapid changes in the volcanic plumbing system (minutes to hours) and in one case precursory signals leading to eruptive activity were detected. The need for true multi-instrument networks is clear if we are to have both the temporal and spatial reso-lution needed for effective volcano monitoring. However, the high cost of these instruments is currently limiting the implementation of continuous microgravity networks. An interim approach to consider is the development of a collaborative network of researchers able to bring multiple instruments together at key volcanoes to investigate multitemporal physical changes in a few type volcanoes. However, to truly move forward, it is imperative that new low-cost instruments are developed to increase the number of instruments available at a single site. Only in this way can both the temporal and spatial integrity of monitoring be maintained. Integration of these instruments into a multiparameter network of continuously recording sensors is essential for effective volcano monitoring and hazard mitigation.
Gravity monitoring of C O2 movement during sequestration: Model studies
Authors: Gasperikova E. , Hoversten G. M.
Published: November 2008

Sequestration/enhanced oil recovery (EOR) petroleum reservoirs have relatively thin injection intervals with multiple fluid components (oil, hydrocarbon gas, brine, and carbon dioxide, or [Formula: see text]), whereas brine formations usually have much thicker injection intervals and only two components (brine and [Formula: see text]). Coal formations undergoing methane extraction tend to be thin [Formula: see text] but shallow compared to either EOR or brine formations. Injecting [Formula: see text] into an oil reservoir decreases the bulk density in the reservoir. The spatial pattern of the change in the vertical component of gravity [Formula: see text] is correlated directly with the net change in reservoir density. Furthermore, time-lapse changes in the borehole [Formula: see text] clearly identify the vertical section of the reservoir where fluid saturations are changing. The [Formula: see text]-brine front, on the order of [Formula: see text] within a [Formula: see text]-thick brine formation at [Formula: see text] depth with 30% [Formula: see text] and 70% brine saturations, respectively, produced a [Formula: see text] surface gravity anomaly. Such an anomaly would be detectable in the field. The amount of [Formula: see text] in a coal-bed methane scenario did not produce a large enough surface gravity response; however, we would expect that for an industrial-size injection, the surface gravity response would be measurable. Gravity inversions in all three scenarios illustrate that the general position of density changes caused by [Formula: see text] can be recovered but not the absolute value of the change. Analysis of the spatial resolution and detectability limits shows that gravity measurements could, under certain circumstances, be used as a lower-cost alternative to seismic measurements.
Gravimetric monitoring of gas-reservoir water influx — A combined flow- and gravity-modeling approach
Authors: Stenvold Torkjell , Eiken Ola , Landrø Martin
Published: November 2008

Knowledge of the magnitude and distribution of water influx can be essential for managing water-drive gas fields. Geophysical fieldwide monitoring can give valuable information, particularly offshore where well control is sparse and observation wells are expensive. Advances in the accuracy of seafloor time-lapse gravimetry have made this method feasible. It can quantify which areas are flooded, providing information complementary to well-monitoring, production, and 4D seismic data. Gravimetric monitoring may aid material-balance calculations, which are vital for assessing reservoir-drive mechanism and estimating initial and remaining gas volumes. In addition, it can constrain reservoir simulation models. Our goal is to produce better physical insight into typical density changes occurring in water-drive gas fields and their associated surface-gravity response. It is feasible to monitor displacement of gas by water in reservoirs that are only a few meters thick. Gravimetric monitoring can detect edgewater encroachment in early stages. With current accuracy, the method is applicable for gas reservoirs of modest size ([Formula: see text] in situ gas volume) at medium depths [Formula: see text].
Geothermal reservoir monitoring with a combination of absolute and relative gravimetry
Authors: Sugihara Mituhiko , Ishido Tsuneo
Published: November 2008

Microgravity monitoring is a valuable tool for mapping the redistribution of subsurface mass and for assessing changes in fluid recharge from reservoir boundaries associated with geothermal exploitation. To further the development of a high-precision absolute/relative hybrid gravity-measurement technique, we conducted measurements using an absolute gravimeter in two geothermal fields in Japan. The absolute gravity measurements were performed in the central production areas to directly measure gravity changes caused by fluid withdrawal. We succeeded in measuring long-term trends within an accuracy of a few microgals in the Okuaizu and Ogiri fields, which have been producing electricity for several years. Absolute measurements in the center of the field provide reliable and local reference datum anchor points for more widely distributed relative gravity measurements. In the Ogiri field, we carried out time-lapse hybrid measurements with this combination of absolute and relative gravimetry and delineated the spatial distributions of long- and short-term changes. The long-term changes are relatively small, considering the four-year observation interval. This suggests a near balance between the mass withdrawal rate from wells and mass recharge from peripheral regions. The apparent balance is reproduced fairly well by a preliminary numerical reservoir simulation study. The observed long- and short-term changes are thought to be useful constraints for planned history-matching studies based on refined reservoir models with greater spatial resolution that incorporate detailed well-by-well production histories.
Monitoring aquifer recharge using repeated high-precision gravity measurements: A pilot study in South Weber, Utah
Authors: Chapman D. S. , Sahm E. , Gettings P.
Published: November 2008

Repeated high-precision gravity surveys were conducted over two infiltration cycles on an alluvial-fan aquifer system at the mouth of Weber Canyon in northern Utah as part of the Weber River Basin Aquifer Storage and Recovery Pilot Project (WRBASR). Gravity measurements collected before, during, and after infiltration events indicate that a perched groundwater mound formed during infiltration events and decayed smoothly following infiltration. Data also suggest the groundwater mound migrated gradually south-southwest from the surface infiltration site. Maximum measured gravity changes associated with the infiltration were [Formula: see text] during the first event (2004) and a net [Formula: see text] increase during the second event (2005). Gaussian in-tegration of the spatial gravity anomaly yields an anomalouscausative mass within 10% of the [Formula: see text] [Formula: see text] of infiltrated water measured in 2004. The spatial gravity field is consistent with a groundwater mound at the end of the infiltration cycle approximately equivalent to a cylindrical disc of height [Formula: see text] and a radius between [Formula: see text]. After infiltration ceased, gravity anomalies decreased to approximately 50% of their original amplitude over a characteristic time of three to four months. The reduction of the gravity signal is simulated by analytical solutions for the decay of a groundwater mound through a saturated porous media. This comparison places relatively tight bounds on the hydraulic conductivity of the alluvial-fan material below the infiltration site with a preferred value of [Formula: see text] on a length scale of a few hundred meters.
Simulating the influence of water storage changes on the superconducting gravimeter of the Geodetic Observatory Wettzell, Germany
Authors: Creutzfeldt Benjamin , Güntner Andreas , Klügel Thomas , Wziontek Hartmut
Published: November 2008

Superconducting gravimeters (SG) measure temporal changes of the Earth’s gravity field with high accuracy and long-term stability. Variations in local water storage components (snow, soil moisture, groundwater, surface water, and water stored by vegetation) can have a significant influence on SG measurements and — from a geodetic perspective — add noise to the SG records. At the same time, this hydrological gravity signal can provide substantial information about the quantification of water balances. A 4D forward model with a spatially nested discretization domain was developed to investigate the local hydrological gravity effect on the SG records of the Geodetic Observatory Wettzell, Germany. The possible maximum gravity effect was investigated using hypothetical water storage changes based on physical boundary conditions. Generally, on flat terrain, a water mass change of[Formula: see text] in the model domain causes a gravity change of [Formula: see text]. Simulation results show that topography increases this value to [Formula: see text]. Errors in the Digital Elevation Model can influence the results significantly. The radius of influence of local water storage variations is limited to [Formula: see text]. Detailed hydrological measurements should be carried out in a radius of [Formula: see text] around the SG station. Groundwater, soil moisture, and snow storage changes dominate the hydrological gravity effect at the SG Wettzell. Using observed time series for these variables in the 4D model and comparing the results to the measured gravity residuals show similarities in both seasonal and shorter-term dynamics. However, differences exist, e.g., the range comparison of the mean modeled [Formula: see text] gravity signal and the measured [Formula: see text] gravity signal, making additional hydrological measurements necessary to describe the full spatiotemporal variability of local water masses.
The 4D microgravity method for waterflood surveillance: Part 3 — 4D absolute microgravity surveys at Prudhoe Bay, Alaska
Authors: Ferguson John F. , Klopping F. J. , Chen Tianyou , Seibert John E. , Hare Jennifer L. , Brady Jerry L.
Published: November 2008

The 4D microgravity method is becoming a mature technology. A project to develop practical measurement and interpretation techniques was conducted at Prudhoe Bay, Alaska, from 1994 through 2002. Beginning in 2003 these techniques have been systematically applied to monitor a waterflood in the gas cap of the Prudhoe Bay reservoir. Approximately 300 stations in a [Formula: see text] area are reoccupied in each survey year with sub-[Formula: see text] precision absolute gravity and centimeter precision Global Positioning System (GPS) geodetic measurements. The 4D gravity measured over epochs 2005–2003, 2006–2003, and 2007–2003 has been successfully modeled to track the mass of water injected since late in 2002. A new and improved version of the A-10 field-portable absolute gravity meter was developed in conjunction with this project and has proven to be a key element in the success of the 4D methodology. The use of an absolute gravity meter in a field survey of this magnitude is unprecedented. There are substantial differences between a 4D absolute microgravity survey and a conventional gravity survey in terms of station occupation procedures, GPS techniques, and the 4D elevation correction. We estimate that the overall precision of the 4D gravity signal in each epoch is less than [Formula: see text].
brachyurynull mutant-induced defects in juvenile ascidian endodermal organs
Authors: Chiba Shota , Jiang Di , Satoh Noriyuki , Smith William C.
Published: November 2008

We report the isolation of a recessive ENU-induced short-tailed mutant in the ascidian Ciona intestinalis that is the product of a premature stop in the brachyury gene. Notochord differentiation and morphogenesis are severely disrupted in the mutant line. At the larval stage,variable degrees of ectopic endoderm staining were observed in the homozygous mutants, indicating that loss of brachyury results in stochastic fate transformation. In post-metamorphosis mutants, a uniform defect in tail resorption was observed, together with variable defects in digestive tract development. Some cells misdirected from the notochord lineage were found to be incorporated into definitive endodermal structures, such as stomach and intestine.
Effects of two-stage impact load on point contact elastohydrodynamic lubrication films
Authors: Nishikawa H , Miyazaki H , Kaneta M , Guo F
Published: November 2008

The behaviour of point contact elastohydrodynamic lubrication (EHL) films under a two-stage impact load is investigated for two cases, in which the initial load is applied or the initial impact gap is given. The film thickness and its profile are observed using the optical interferometry technique. It is found that the film thickness profile obtained by the two-stage impact load is approximately estimated by superposing the film thickness profiles produced independently by the corresponding two impact loads. It is also proved that the impact load under rolling and/or sliding conditions brings about a crescent-shaped oil entrapment only at the inlet periphery of the EHL conjunction, and the lubricant passes through the conjunction at approximately the entrainment velocity. Therefore, the film in the EHL conjunction is not directly influenced by the impact load.
Two-dimensional steady-state thermal elasto-plastic contact of rough surfaces
Authors: Liu G , Liu T , Xie Q , Wang Q J
Published: November 2008

A finite-element deterministic two-dimensional thermal elasto-plastic contact model is presented in this article, which facilitates the investigation of the influence of steady-state frictional heating on contacting asperities and subsurface stress fields. This model takes into account the asperity distortion caused by the temperature variation in a tribological process, microplastic flow of surface asperities, and coupled thermo-elasto-plastic behaviour of the material, with and without considering the strain-hardening property of the material. The model is verified through the contact analysis of a rigid, isothermal cylinder with a thermally conductive, elasto-plastic plane. The maximum contact pressures increase with frictional heating. Furthermore, thermal effects on the contact pressure, real area of the contact, and average gap of a real rough surface with different frictional heat inputs under thermal elasto-plastic contact conditions are numerically investigated. It indicates that neglecting thermal effect overestimates the real area of the contact and underestimates the average gap between the contacting surfaces.
Tribology of compression ring-to-cylinder contact at reversal
Authors: Mishra P C , Balakrishnan S , Rahnejat H
Published: November 2008

Piston ring-pack-to-cylinder contact accounts for one of the major sources of frictional losses in internal combustion engines. The regime of lubrication alters during the piston cycle because of the transient nature of applied load and kinematic contact conditions. Ring geometry, surface topography, and lubricant rheology also play an important role. The aim is to attain full fluid film lubrication, thus reducing friction because of boundary interactions. Therefore, accurate prediction of lubricant film thickness and pressure distribution constitutes the first step in a proper analysis of piston ring—cylinder conjunction. The creation of a gap through elastic deformation is sought in order to inhibit asperity tip interactions. The generated contact pressures in the lubricant film are due to combined entraining motion and squeeze film effect. The integrated pressure distribution balances the elastic force due to ring tension and the applied combustion pressure acting behind the ring. The article highlights a detailed analysis, which forms the basis for its future expansion to include the study of mixed regime of lubrication, which may be prevalent in some real engines.
Stability analysis of a flexible rotor supported on finite hydrodynamic porous journal bearing using a non-linear transient method
Authors: Laha S K , Banjare H , Kakoty S K
Published: November 2008

A theoretical analysis has been carried out to study the stability of a flexible rotor supported on two symmetrical finite porous oil journal bearings at the two ends. The rotor is modelled by Timoshenko beam theory. An investigation of stability has been carried out using a non-linear transient method. This analysis enables to trace the journal centre locus at different locations of the rotor, however, only the bearing location rotor centre trajectories are taken up in this work and subsynchronous critical parameters are estimated. Several trajectories of the journal centre have been obtained for different operating conditions. The stability curves have been drawn for different eccentricity ratios. This work has been carried out in non-dimensional form and the effects of bearing feeding parameter, slenderness ratio, and material properties of the beam on stability are investigated.
Reiterated homogenization applied in hydrodynamic lubrication
Authors: Almqvist A , Essel E K , Fabricius J , Wall P
Published: November 2008

This work is devoted to studying the combined effect that arises due to surface texture and surface roughness in hydrodynamic lubrication. An effective approach in tackling this problem is by using the theory of reiterated homogenization with three scales. In the numerical analysis of such problems, a very fine mesh is needed, suggesting some type of averaging. To this end, a general class of problems is studied that, e.g. includes the incompressible Reynolds problem in both Cartesian and cylindrical coordinate forms. To demonstrate the effectiveness of the method several numerical results are presented that clearly show the convergence of the deterministic solutions towards the homogenized solution. Moreover, the convergence of the friction force and the load-carrying capacity of the lubricant film is also addressed in this paper. In conclusion, reiterated homogenization is a feasible mathematical tool that facilitates the analysis of this type of problem.
Effect of CeO2 addition on the microstructure, hardness, and abrasive wear behaviour of flame-sprayed Ni-based coatings
Authors: Sharma S P , Dwivedi D K , Jain P K
Published: November 2008

This article describes the effect of addition of CeO2 on the microstructure, hardness, and abrasive wear behaviour of Ni-based flame-sprayed coatings. These coatings are economical but not frequently used because of their high porosity, low hardness, and bigger grain size. The mechanical and tribological properties of the coatings are governed by the microstructure, grain size, and distribution of various elements. Rare earth elements (oxides) refine the microstructure. The commercially available Ni-based powder was modified with the addition of CeO2 (0.4, 0.8, 1.2, 1.6, and 2 %wt). The conventional Ni-based coatings and those containing various amounts of CeO2 were compared in terms of grain size and distribution of various elements, hardness, porosity, and abrasive wear behaviour. The addition of an optimal amount of CeO2 (0.8 %wt) refines the grain size and improves hardness and abrasive wear resistance of the coatings. X-ray diffraction of the conventional and modified coating with an optimum addition of CeO2 (0.8 %wt) was also carried out to identify the various phases present in the coating.
The tribochemical study of two triazine derivatives as additives in rapeseed oil
Authors: Li J , Ren T-H
Published: November 2008

Two novel S—P–N-type triazine derivatives, 2,4-bis-amino-6-( O, O′-dialkyl dithiophos-phate)- s-1,3,5-triazines (coded DBBT and DPBT) were synthesized. The tribological behaviours of these derivatives as additives in rapeseed oil were evaluated using a four-ball machine. The results show that the triazine derivatives possess excellent extreme pressure capacities, friction-reducing properties, and high thermal stabilities. Under low-load range (196–392 N) and high-additive concentration (5 wt%), DPBT has anti-wear properties superior to zinc dialkyldithiophosphates. The action mechanism was investigated using X-ray photoelectron spectroscopy and scanning electron microscope. It is proposed that the prepared compounds as additives in rapeseed oil form a protective film containing phosphate, sulfate, and organic nitrogen compound on the rubbed surface.
Oscillating circular squeeze films considering the combined effects of fluid inertial forces and non-Newtonian couple stresses
Authors: Lin J-R
Published: November 2008

Based on the microcontinuum theory, the combined effects of fluid inertial forces and non-Newtonian properties on the oscillating squeeze films of parallel circular discs are investigated theoretically. By applying the momentum approximation method, the pressure-gradient lubrication equation is derived from Stokes couple-stress momentum equations including total fluid inertial terms to account for the non-Newtonian effects arising from a Newtonian base fluid blended with various sorts of additives. A closed-form solution for the oscillating squeeze-film characteristics is then obtained. From the results presented, the combined effects of fluid inertial forces and non-Newtonian couple stresses are characterized by both the squeezing Reynolds number and the couple-stress parameter depending on the amplitude of oscillation. Comparing with the non-inertia Newtonian-lubricant case, the effects of inertial forces ( Re=18) provide an increase in the fluid film force to ∼52 per cent for the non-dimensional oscillating amplitude A*=0.3 at the time instant t*=1.7453. Using non-Newtonian fluids as lubricants, the combined effects of fluid inertial forces ( Re=18) and non-Newtonian couple stresses ( L=0.1) further increase the fluid film force up to ∼86 per cent when compared with the non-inertia Newtonian-lubricant case.
The effect of air shear force moment on the performance of slider air bearings in hard disk drives
Authors: Zhang B , Nakajima A
Published: November 2008

The shear force moment was included in the design model of air bearings for hard disk drives, and the effect of the shear force moment was investigated with some numerical results. It was found that the shear force moment tends to increase the load capacity and reduce the pitch angle of the air bearing. It is concluded that the shear force moment must be incorporated into the design model of air bearings of hard disk drives.
Connectivity between plasticity and brittle fracture: An overview from nanoindentation studies
Authors: Gerberich W W , Stauffer D D , Beaber A R , Mook W M
Published: November 2008

Nanoindentation and scanning probe microscopy techniques applied to deforming thin films, nanospheres, nanowires, and nanocrystalline structures have uncovered new mechanical property phenomena dependent on size scale. This overview addresses several segments — those associated with measurement by nanoindentation, as well as the resulting properties of elasticity and plasticity, and fracture toughness of semi-brittle crystals. Specific to volumes in indentation or compression, it is shown that both pressure and scale effects can become dominant for both elasticity and plasticity at sizes less than 100nm. A strong inverse relationship between yield strength and activation volume for both single crystal and nanocrystalline structures is reviewed. Equally strong is a relationship between fracture toughness, the number of shielding dislocations accommodating indentation prior to fracture, and the basic mechanical and physical properties of semi-brittle solids. The link between fracture toughness and plasticity in these semi-brittle materials is shown to be the activation volume for dislocation nucleation in these strong solids.
Emotional labour demands, wages and gender: A within‐person, between‐jobs study
Authors: Bhave Devasheesh P. , Glomb Theresa M.
Published: November 2008

Although research suggests the important role of gender in emotional labour, its effect on the relationship between emotional labour demands and wages has not been examined explicitly. The current study investigates this relationship by testing hypotheses derived from theories of vocational choice and labour market supply and demand. Hypotheses are tested using a unique within‐person, between‐jobs longitudinal dataset with information on two jobs for each worker in a national sample of U.S. workers (N=5,488). After controlling for relevant variables related to wages, results suggest men incur wage penalties of approximately 6% when moving to occupations with higher emotional labour demands. Women do not experience statistically significant wage effects from moving to an occupation with higher emotional labour demands. These findings are discussed and interpreted based on the theoretical frameworks.
Climate Change and the Future of Taste
Authors: field michele
Published: November 2008

Until now, the impact of the expected climate changes on food has been almost entirely about crop yields, and fantasies about how olives might flourish in Oklahoma. This piece takes a narrow focus, asking how the changes in rainfall patterns and temperatures will possibly affect what a tomato tastes like, or whether the ““beef”” that our children enjoy will be too different for us to enjoy. Many important changes will be to the flavors of fish (already most palates can taste a difference between wild shrimp and farmed) and those foods relying on fragile herbs and flavors like vanilla. If food scenarios become very bad, no one is going to die from the loss of genuine basmati rice, but it is important to anticipate what we will lose. And enjoy it while we can.
The Stray Shopping Cart Project
Authors: montague julian
Published: November 2008

The Project is a long term conceptual art project that documents and categorizes stray shopping carts based on the situations in which they are found. The overarching goal was to look at the ways in which language and scientific systems of classification shape our perception of things. Thousands of stray carts have been catalogued and categorized into thirty-three types. The two man types are Class A: False Carts and Class B: True Carts. Photographs from the project are included in the article.
The Banquet Years: FOOD, A SoHo Restaurant
Authors: waxman lori
Published: November 2008

For a few years beginning in 1971, the restaurant FOOD served as a center of life for a diverse group of artists who called Manhattan's SoHo home. Founded by local artists Carol Goodden, Gordon Matta-Clark and Tina Girouard, FOOD's flexible working hours and creative, exotic, homemade dishes added to the growing cultural and communal energy of a transitional neighborhood of raw lofts and alternative art spaces. The restaurant served not just as a place to work and eat: Matta-Clark designed the space's unorthodox layout, conceptual dinners were served on Sunday nights, and the whole functioned less according to the imperatives of a business than of an experiment in the melding of art and life.
The Walpole Society Goes to Dinner
Authors: schinto jeanne
Published: November 2008

This is a profile of Edna Greenwood (1888-1972) who today is considered one of our first important collectors of American antiques, as well as our country's first significant collectors of culinaria. Whether she or anyone around her realized it at the time, she may have been our first American culinary historian of sorts. Beside being a mini-biography, this is also the story of an 18th-century-style dinner that Greenwood served one night in September 1946 to members of the Walpole Society, an exclusive all-male antiques-collector club founded in 1910 and still in existence. The meal took place at her restored Time Stone Farm in Marlborough, Massachusetts, where she and her family lived for decades without electricity and other conveniences. The narrative includes a description of the food and thumbnails of the guests (Henry du Pont was one). The epilogue discusses how her pioneering collections came to rest at the Smithsonian Institution.
Medium-Size Me
Authors: hinch jim
Published: November 2008

Organic farming has come a long way since its early countercultural beginnings. But organic produce remains only a tiny fraction of the American food market, and organic farming itself has begun feeling some of the economic pressures more commonly associated with agribusiness. American eating habits, though changing at the edges, remain largely wedded to processed, conventionally grown foods. Part of the problem is the near total disconnect between eaters and growers––a disconnect as profound at the top as at the bottom of the nation's economic scale. This story aims to breach that gap by focusing in detail on the lives and livelihoods of a few farmers in upstate New York who have managed to resolve many of the paralyzing contradictions in America's food economy by aiming for a sustainable, mid-scale agriculture that is neither unattainably off the grid nor excessively compromised by agribusiness consolidation.
Infants' Memory for Isolated Tones and the Effects of Interference
Authors: Plantinga Judy , Trainor Laurel J.
Published: November 2008

IN MOST ADULTS, PITCH MEMORY FOR SINGLE tones is of short duration, and the presence of interference reduces performance in pitch matching tasks.We show that 6-month-old infants can remember the pitch of a tone for at least 2.5 s but that, like adults, their memory is disrupted by tones interpolated between repetitions of the tone-to-be-remembered. For both infants and adults, we found a significant negative correlation between the number of interference tones and proportion correct in detecting a change in pitch. Performance reached chance levels with 5 interference tones for infants, and 15 interference tones for adults. This indicates that although there may be a developmental increase with age in the length of time a memory can be held, for both 6-month-old infants and adults, memory for the absolute pitch of isolated tones fades rapidly.
Phase Correction in Sensorimotor Synchronization with Nonisochronous Sequences
Authors: Repp Bruno H. , London Justin , Keller Peter E.
Published: November 2008

PHASE CORRECTION, WHICH IS NECESSARY for synchronization of movements with a rhythm, has been studied primarily with isochronous sequences.We used a phase perturbation method to examine phase correction in synchronization with nonisochronous sequences (3:2 interval ratios), using musically trained participants. In isochronous control sequences, the phase correction response (PCR) of the tap following a small phase shift was larger when the intervals were long (600 ms) than when they were short (400 ms). In nonisochronous cyclic two-interval patterns, we found a similar dependence of the PCR on the duration of the interval following a phase shift. In three-interval patterns, however, there was no clear dependence on interval duration. The metrical interpretation of the sequences (downbeat location) had no effect on phase correction. In general, phase correction was as effective with nonisochronous as with isochronous sequences.
A River Valley Segment Classification of Michigan Streams Based on Fish and Physical Attributes
Authors: Brenden Travis O. , Wang Lizhu , Seelbach Paul W.
Published: November 2008

Water resource managers are frequently interested in river and stream classification systems to generalize stream conditions and establish management policies over large spatial scales. We used fish assemblage data from 745 river valley segments to develop a two‐level, river valley segment‐scale classification system of rivers and streams throughout Michigan. Regression tree analyses distinguished 10 segment types based on mean July temperature and network catchment area and 26 segment types when channel gradient was also considered. Nonmetric multidimensional scaling analyses suggested that fish assemblages differed among segment types but were only slightly influenced by channel gradient. Species that were indicative of specific segment types generally had habitat requirements that matched segment attributes. A test of classification strength using fish assemblage data from an additional 77 river valley segments indicated that the classification system performed significantly better than random groupings of river valley segments. Our classification system for river valley segments overcomes several weaknesses of the classifications previously used in Michigan, and our approach may prove beneficial for developing classifications elsewhere.