bluuebunny/crossref_metadata_2025 huggingface dataset:
Postresection CA 19-9 Predicts Overall Survival in Patients With Pancreatic Cancer Treated With Adjuvant Chemoradiation: A Prospective Validation by RTOG 9704
Authors: Berger Adam C. , Garcia Miguel , Hoffman John P. , Regine William F. , Abrams Ross A. , Safran Howard , Konski Andre , Benson Alan B. , MacDonald John , Willett Christopher G.
Published: November 2008

Purpose

CA 19-9 is an important tumor marker in patients with pancreatic adenocarcinoma. A secondary end point of Radiation Therapy Oncology Group trial 9704 was prospective evaluation of the ability of postresectional CA 19-9 to predict survival.

Methods

CA 19-9 expression was analyzed as a dichotomized variable (< 180 v ≥ 180) or (≤ 90 v > 90). Cox proportional hazards models were utilized to identify the impact of CA 19-9 expression on overall survival (OS). Actuarial estimates for OS were calculated using Kaplan-Meier methods.

Results

Three hundred eighty-five patients patients had assessable CA 19-9 levels. The majority had a CA 19-9 level lower than 180 or ≤ 90 (n = 220 and 200, respectively), while 34% were Lewis Antigen negative and 33 (9%) and 53 (14%) patients had levels higher than 180 and higher than 90. When CA 19-9 was analyzed as a dichotomized variable, there was a significant survival difference favoring patients with CA 19-9 lower than 180 (hazard ratio [HR], 3.53; P < .0001). This corresponds to a 72% reduction in the risk of death for patients with a CA 19-9 lower than 180. This was also true for patients with CA 19-9 ≤ 90 (HR, 3.4; P < .0001). Multivariate analyses confirmed that CA 19-9, when analyzed as both a continuous and a dichotomized variable, is a highly significant predictor of OS in patients with resected pancreatic cancer.

Conclusion

To our knowledge, this is the first phase III trial to perform prospective analysis of CA 19-9 levels in patients treated with adjuvant chemoradiotherapy. It definitively confirms the prognostic importance of postresectional CA 19-9 levels after surgery with curative intent in patients with pancreatic cancer.
Mediating Creative Nature and Human Needs in Early German Political Economy
Authors: Bowler Richard
Published: November 2008

At its inception in the early nineteenth century, political economy in the German territories offered a new science that explored the dynamic interrelationship between human activity and natural processes. An emphasis on the complexity of human needs and the efforts to satisfy them furnished the emerging discipline with a solid anthropological foundation. Nevertheless, German political economists recognized the significant role played by nature in shaping and sustaining the human economy, a recognition that informed their approach to economic science.
Cambridge as aPlacein Economics
Authors: Marcuzzo Maria Cristina , Naldi Nerio , Sanfilippo Eleonora , Rosselli Annalisa
Published: November 2008

Cambridge as a geographical reference often crops up in the characterisation of the economic theories and approaches that developed in Cambridge (UK) between the 1920s and the 1960s with the contribution of economists who did not always share the same interests, background or attitudes, but who all lived and worked – for considerable periods of time – in that particular corner of the world.

In order to reconstruct the Cambridge of those years and explore the space it represented for economics we have selected a group of economists and a span of time – essentially between the two wars, with a few encroachments in the years following on the death of Keynes. Cambridge was not only a place, but also a play of magnetic forces, drawing together and driving apart, where ideas emerged from an environment formed through intense human and professional relations, a well defined cultural tradition and a way of its own of organising work and study. We present the dramatis personae and the background to their actions, and consider the characteristics of intellectual and personal communication on the basis of which we are led to define the Cambridge economists examined more as a `group' than a school.
The Impact of Open Access to Fishing Grounds: The History of Jens Warming's Model
Authors: Topp Niels-Henrik
Published: November 2008

The paper examines the Dane Jens Warming's published and unpublished works on fisheries economics from the period 1911–38. In 1911 Warming published a highly original article on the problems of open access to a common property resource. The article contains the same results as H. Scott Gordon presented in his seminal article on fisheries economics from 1954. Warming frequently returned to his model later in life. The reason for doing so was that the model not only dealt with an important aspect of fisheries management but also illustrated a more general problem relating to the functioning of a competitive economy. Special attention is drawn to an unpublished manuscript from 1926, which includes Warming's own English presentation of a new version of the model. The new model became the main ingredient in a new article on fishery from 1931 and was included in the sections on fishery in Warming's textbooks on the Danish society published in 1929 and 1938. The paper draws attention to Warming's efforts to make his contemporaries take an interest in his publications. New findings in the archives indicate that Warming attempted to make Scandinavian marine biologists aware of his views on fisheries economics from the very outset.
An Experiment with Regulated Competition and Individual Mandates for Universal Health Care: The New Dutch Health Insurance System
Authors: Rosenau Pauline Vaillancourt , Lako Christiaan J.
Published: November 2008

The 2006 Enthoven-inspired Dutch health insurance reform, based on regulated competition with a mandate for individuals to purchase insurance, will interest U.S. policy makers who seek universal coverage. This ongoing experiment includes guaranteed issue, price competition for a standardized basic benefits package, community rating, sliding-scale income-based subsidies for patients, and risk equalization for insurers. Our assessment of the first two years is based on Dutch Central Bank statistics, national opinion polls, consumer surveys, and qualitative interviews with policy makers. The first lesson for the United States is that the new Dutch health insurance model may not control costs. To date, consumer premiums are increasing, and insurance companies report large losses on the basic policies. Second, regulated competition is unlikely to make voters/citizens happy; public satisfaction is not high, and perceived quality is down. Third, consumers may not behave as economic models predict, remaining responsive to price incentives. Finally, policy makers should not underestimate the opposition from health care providers who define their profession as more than simply a job. If regulated competition with individual mandates performs poorly in auspicious circumstances such as the Netherlands, how will this model fare in the United States, where access, quality, and cost challenges are even greater? Might the assumptions of economic theory not apply in the health sector?
THE Gendercator, OR HOW I LEARNED TO STOP WORRYING AND LOVE THE BLOGOSPHERE
Authors: Lawless Jessica
Published: November 2008

This essay is a collection of statements, thoughts and opinions that exploded across the internet in response to a controversy that occurred during the 2007 LGBT film festival season. Catherine Crouch's short, The Gendercator, is the first film to be accepted and then removed from San Francisco's Frameline Film Festival, the longest running festival of its kind. The censorship of the film due to community pressure, and the transphobic storyline Crouch created raises central questions of community and identity/post identity politics – personal experience versus group representation, strategies for creating institutional spaces where queer identity formation can both develop and change, and problems that occur when grassroots organizations gain cultural cache that allows mobility for some but not for others.

I became involved when I was invited to sit on a panel with Crouch and others following the screening of The Gendercator at Outfest in Los Angeles. Rather than offer a personal account of the panel, a reading of the film, or analysis of the varying viewpoints and decisions made surrounding The Gendercator, I have relied on “blogosphere” and cyber world to tell this story. They rivaling voices from the LGBTQIA community beautifully convey all of the salient, ironic, painful, political and humorous positions as is. I have added my own positioning on key issues along the way. These are in the footnotes rather than the main text. This is not a strategy to perform the impossible act of journalistic “neutrality,” but a conceptual move to contribute to the already loud and disharmonious cacophony surrounding The Gendercator. My contributions can be read as post blog postings, extending the web based conversation into another dimension, material based text.
TFT-LCD Mura defects automatic inspection system using linear regression diagnostic model
Authors: Chen S-L , Chang J-H
Published: November 2008

The TFT-LCD panel is one of the most important and promising products in the recent years. Mura defects can be created on the display panel during its production. In this research, a linear regression diagnostic model is incorporated with digital image processing theory to automatically inspect for Mura defects. A bivariate polynomial regression model is used to simulate the brightness of background images that is used in the diagnosis of outliers and influential points. The partitions of the candidate Mura defect regions are segmented using Niblack's threshold criteria. The candidate Mura defects are further evaluated. The quantified level is defined in terms of concepts already reported in the literature. Based on Weber's law and a visual perception model, the just-noticeable intensity difference index of the Mura features can be obtained and it can be subsequently used to quantify the Mura defect level. With the obtained defect level, Mura defects can be identified for exactly labelling of the perfect and imperfect LCD panels.

Experiments were performed on 13 TFT-LCD panels. There are ten bad panels and three good panels in these 13 samples as determined by human visual inspection. Each bad panel has at least one Mura defect. After the automated inspection process, the results showed that the proposed method could separate the good and bad panels accurately. Compared with human visual inspection, the Mura detection rate of the distinct size and shapes can attain over 90.9 per cent correct detection and the achieved correction rate of Mura defects on each panel can be improved by 100 per cent.
A new project scheduling approach for improving multi-product multi-period production planning problems
Authors: Noori S , Bagherpour M , Zorriassatine F , Makui A , Parkin R
Published: November 2008

The problem of matching production levels for individual products to demand fluctuations during multiple periods is known in the production planning literature as the multi-product multi-period (MPMP) problem. Linear programming (LP)-based solutions have been extensively reported in this respect. MPMP problems are commonly solved by using either analytic or simulation methods. More recently, hybrid solutions consisting of both analytical models and simulation analysis have been proposed where some operational criteria, e.g. the order of visit to machining centres, are taken into account. In this paper, results related to some of the literature based on hybrid solutions are used as the initial feasible solutions and then examined in the context of project scheduling by considering the influences of resource constraints. After converting the MPMP to a project network problem and assigning resources to activities and consequently levelling the resource profiles, it is discovered that machine utilization can be further improved by applying unused machine capacities. A LP model is therefore developed in order to maximize feasible production rates over all the production planning periods. The proposed approach results in improvements on the results of earlier hybrid solutions reported in the literature. Finally, three different planning problems are suggested for further applications of the proposed approach in the context of manufacturing environments.
Warm deep drawing of magnesium alloy sheets — formability and process conditions
Authors: Ren L M , Zhang S H , Palumbo G , Tricarico L
Published: November 2008

The influence of deformation conditions on the formability of magnesium alloy was systematically investigated using the experimental method and finite element analysis. The research activity aimed to gain further insight into the formability of magnesium alloy AZ31 (aluminium 3 wt per cent, zinc 1 wt per cent) and to have first-hand knowledge of the correlations between the material's properties and the processing parameters. In this work, the mechanical properties of magnesium alloy AZ31 sheet were analysed according to the results of tensile tests. A set of experimental equipment with temperature control was employed to perform warm deep drawing of magnesium alloy AZ31 sheets under various forming conditions. The most important process parameters, including the punch speed, the forming temperature, and the geometrical shape of the blank, were taken into account and optimal values were proposed. Finite element analyses were also performed to evaluate the effects of the process parameters on the formability of rectangular cup drawing and to predict the process defects during the process.
Investigation into flexural characteristics of a bar subjected to local heating: The effect of heat source location
Authors: Alzaharnah I T , Yilbas B S
Published: November 2008

The flexural motion of a bar subjected to local heating, resembling the welding process, is considered and the influence of the location of the heat source on the flexural characteristics is examined. A temperature heat source is assumed along the width of the bar to account for the local heating. Temperature-dependent mechanical properties such as elastic modulus are accommodated in the simulations. This modifies the amplitude and the frequency of the flexural wave generated in the bar. A numerical scheme using the finite element method is introduced to predict the flexural characteristics. It is found that the amplitude difference of the flexural wave owing to heating and no-heating situations varies with changing the location of the heat source. This is also true for the time period difference of the flexural waves owing to heating and no-heating situations of the bar.
Data mining in manufacturing: Significance analysis of process parameters
Authors: Perzyk M , Biernacki R , Kozlowski J
Published: November 2008

Determination of the most significant manufacturing process parameters using collected past data can be very helpful in solving important industrial problems, such as the detection of root causes of deteriorating product quality, the selection of the most efficient parameters to control the process, and the prediction of breakdowns of machines, equipment, etc. A methodology of determination of relative significances of process variables and possible interactions between them, based on interrogations of generalized regression models, is proposed and tested. The performance of several types of data mining tool, such as artificial neural networks, support vector machines, regression trees, classification trees, and a naïve Bayesian classifier, is compared. Also, some simple non-parametric statistical methods, based on an analysis of variance (ANOVA) and contingency tables, are evaluated for comparison purposes. The tests were performed using simulated data sets, with assumed hidden relationships, as well as on real data collected in the foundry industry. It was found that the performance of significance and interaction factors obtained from regression models, and, in particular, neural networks, is satisfactory, while the other methods appeared to be less accurate and/or less reliable.
A new approach for inverse analysis of springback in a sheet-bending process
Authors: Behrouzi A , Dariani B M , Shakeri M
Published: November 2008

In sheet metal-forming processes, the final product can deviate from the target shape as a result of springback. Several approaches have been proposed for analysis of springback and compensating for its error. In this paper, a new approach for springback analysis is presented based on inverse modelling. The springback occurs at the last step of the process and the final geometry of the workpiece can be obtained at the end of direct process modelling. By applying inverse springback analysis, iterative die design becomes possible from the end of the process. Applying bending theory in an inverse algorithm, compensation of springback error is performed in the V-bending process. Convergence of the inverse approach is compared with the direct approach. The inverse springback analysis is developed for three-dimensional analysis of sheet metal forming by applying the explicit—implicit finite element method. Inverse springback modelling of asymmetric and large springback processes is feasible by this new algorithm. The capability and accuracy of this method are investigated for various symmetric and asymmetric processes by comparing results of the method by three-dimensional finite element analysis and V-bending experimental results.
Advances in the turning process for productivity improvement — a review
Authors: Sharma V S , Dogra M , Suri N M
Published: November 2008

Increasing productivity and reducing manufacturing cost have always been keys to successful business. In machining, higher values of cutting parameters offer opportunities for increasing productivity, but this also involves greater risk of deterioration in surface quality and tool life. During the past decade significant advances have been made in the development of cutting tool materials for machining of ‘difficult-to-cut’ materials. The cost involved in the production of new turning tools is very high. To overcome this cost factor researchers have tried to bring about modifications in the turning process using existing tool materials. A good understanding of the cutting conditions, temperature generation, failure modes, and cutting forces leads to efficient control of the turning process. The literature reveals that modifications in the tool geometry (such as grooved/restricted contact tools (RCTs) and chamfered/honed edges), applications of cooling techniques, ultrasonic assisted turning (UAT), hot machining, and cryogenic treatment of inserts have led to efficient and economic machining of modern materials used for aerospace, steam turbine, bearing industry, nuclear, and automotive applications. This paper presents a review of the different techniques involved in turning which can supplement the performance of cutting tools for improved economics, good surface finish, and surface integrity during machining of the latest materials.
An analytical contact model for finite element analysis of tube spinning process
Authors: Lexian H , Dariani B M
Published: November 2008

This work presents an analytical contact model for non-linear dynamic finite element (FE) analysis of the tube spinning process that is based on the Belytschko—Lin—Tsay shell element with an explicit time integration scheme. A brief description of the FE formulation of a first-order shear deformation shell element as well as internal forces calculation, nodal mass calculation, and prediction of stable time step are presented. An analytical contact model is developed for a general roller. Analytical equations of the roller surfaces, interpenetration, and unit vector normal to the contact surface are determined. Contact forces are approximated by a penalty method with a suitable estimation of the penalty coefficient. An explicit FE code, using the developed analytical contact model, is designed and its implementation algorithm is described in detail. The dome forming process of a seamless pressure vessel is simulated using this code, in which the contact analysis is performed robustly, which saves significant amounts of computer time. A steel alloy DIN 1.7225 seamless pressure vessel, which was formed by a hot-spinning process, is cut longitudinally and its profile is measured. A comparison between the longitudinal cross-section profiles calculated by FE analysis and that obtained from experiment shows a good agreement.
The effect of ordering policies for a manufacturing cell changing to lean production
Authors: Bhat S
Published: November 2008

Over the past two decades, lean production has been replacing traditional manufacturing techniques around the world, mainly owing to the success of the Toyota Motor Company. One key to Toyota's success that many Indian companies have not been able to emulate is the transformation of their suppliers to the lean philosophy. The focus of this research is analysing the impact of ordering policies for supplied parts of a manufacturing cell utilizing lean production techniques. This paper presents a simulation analysis of a multi-stage, lean manufacturing cell that produces a family of products. The analysis investigates how the ordering policy for supplied parts affects the performance of the cell under conditions of demand variability and imperfect supplier performance. The ordering policies evaluated are a periodic-review inventory control policy and two Kanban policies. The performance of the cell is measured by the flow time of the product through the cell, the on-time-delivery to the customer, the number of products shipped each week, the amount of work-in-process inventory in the cell, the approximate percentage of time the cell was stocked out, and the average supplied part inventory levels for the cell.
Multi-sensor driver drowsiness monitoring
Authors: Boyraz P , Acar M , Kerr D
Published: November 2008

A system for driver drowsiness monitoring is proposed, using multi-sensor data acquisition and investigating two decision-making algorithms, namely a fuzzy inference system (FIS) and an artificial neural network (ANN), to predict the drowsiness level of the driver. Drowsiness indicator signals are selected allowing non-intrusive measurements. The experimental set-up of a driver-drowsiness-monitoring system is designed on the basis of the sought-after indicator signals. These selected signals are the eye closure via pupil area measurement, gaze vector and head motion acquired by a monocular computer vision system, steering wheel angle, vehicle speed, and force applied to the steering wheel by the driver. It is believed that, by fusing these signals, driver drowsiness can be detected and drowsiness level can be predicted. For validation of this hypothesis, 30 subjects, in normal and sleep-deprived conditions, are involved in a standard highway simulation for 1.5h, giving a data set of 30 pairs. For designing a feature space to be used in decision making, several metrics are derived using histograms and entropies of the signals. An FIS and an ANN are used for decision making on the drowsiness level. To construct the rule base of the FIS, two different methods are employed and compared in terms of performance: first, linguistic rules from experimental studies in literature and, second, mathematically extracted rules by fuzzy subtractive clustering. The drowsiness levels belonging to each session are determined by the participants before and after the experiment, and videos of their faces are assessed to obtain the ground truth output for training the systems. The FIS is able to predict correctly 98 per cent of determined drowsiness states (training set) and 89 per cent of previously unknown test set states, while the ANN has a correct classification rate of 90 per cent for the test data. No significant difference is observed between the FIS and the ANN; however, the FIS might be considered better since the rule base can be improved on the basis of new observations.
Study of the correlation between the performances of lunar vehicle wheels predicted by the Nepean wheeled vehicle performance model and test data
Authors: Wong J Y , Asnani V M
Published: November 2008

This paper describes the results of a study of the correlation between the performances of wheels for lunar vehicles predicted using the Nepean wheeled vehicle performance model (NWVPM), developed under the auspices of Vehicle Systems Development Corporation, Ottawa, Canada, and the corresponding test data presented in ‘Performance evaluation of wheels for lunar vehicles’, Technical Report M-70-2, prepared for George C. Marshall Space Flight Center, National Aeronautics and Space Administration (NASA), USA, by the US Army Engineer Waterways Experiment Station (WES). The NWVPM was originally developed for design and performance evaluation of terrestrial off-road wheeled vehicles. The purpose of this study is to assess the potential of the NWVPM for evaluating wheel candidates for the new generation of extra-terrestrial vehicles. Two versions of a wire-mesh wheel and a hoop-spring wheel, which were considered as candidates for lunar roving vehicles for the NASA Apollo program in the late 1960s, together with a pneumatic wheel were examined in this study. The tractive performances of these wheels and of a 4×4 test vehicle with the pneumatic wheels on air-dry sand were predicted using the NWVPM and compared with the corresponding test data obtained under Earth's gravity and previously documented in the above-named report. While test data on wheel or vehicle performances obtained under Earth's gravity may not necessarily be representative of those on extra-terrestrial bodies, because of the differences in gravity and in environmental conditions, such as atmospheric pressure, it is still a valid approach to use test data obtained under Earth's gravity to evaluate the predictive capability of the NWVPM and its potential applications to predicting wheel or wheeled rover performances on extra-terrestrial bodies. Results of this study show that, using the ratio ( P20/ W) of the drawbar pull to normal load at 20 per cent slip as a performance indicator, there is a reasonable correlation between the predictions and experimental data. This indicates that the NWVPM has the potential as an engineering tool for evaluating wheel candidates for a future generation of extra-terrestrial vehicles, provided that appropriate input data are available.
Particle and nanoparticle characterization at the exhaust of internal combustion engines
Authors: Tornatore C , Merola S S , Vaglieco B M
Published: November 2008

The aim of this work is the characterization of the emissions of exhaust particles in terms of number size distribution and chemical—physical properties. Laser-induced incandescence and broadband ultraviolet—visible extinction and scattering spectroscopy were used at the exhaust of a common-rail diesel engine and of a port fuel injection (PFI) spark ignition (SI) engine. The optical results were compared with size distributions obtained with an electrical low-pressure impactor and a scanning mobility particle sizer. Moreover, the fundamental engine parameters and the particulate mass and gas concentrations were measured using conventional instrumentation.

With respect to the diesel engine, the effect of the exhaust after-treatment was investigated. The exhaust gas recirculation influenced the particle size distribution in terms of number concentration owing to the formation of accumulation mode particles. The catalysed diesel particulate filter strongly reduced the particle number concentration in the loading phase. Effects on the chemical nature of the particles were observed during the filter regeneration phase.

With respect to the PFI SI engine, high number concentrations of nanoparticles ( D<50nm) were measured for all the engine operating conditions. The chemical nature of the nanoparticles was investigated.
Physical aspects of wear of the piston-ring—cylinder set of combustion engines
Authors: Kazmierczak A
Published: November 2008

The research presented in this paper has shown that the physical aspects of interfacial phenomena, described by the total value of surface free energy and the values of its components, make it possible to select more suitable materials for sliding pairs. The total value of surface free energy depends on the molecular structure and the bonds characteristic of a given material, and determines its hardness. In order to reduce friction losses in a sliding pair that is being designed, it is proposed to match such materials for the pair in such a way that the surface of one of them has a high sum of surface free energy components originating from van der Waals interactions, while the other material's surface has a possibly low value of the sum. Furthermore, proper values of the components of surface free energy ensure proper wettability with lubricating oil. In order to minimize friction in a sliding contact, the element with the larger surface area (e.g. a cylinder sleeve) should have larger dispersion and van der Waals forces compared with those of the oil, while the element with the smaller area (e.g. a piston ring) has to have smaller (as low as possible) dispersion and van der Waals forces compared with those of the lubricating oil. Thus a basis for reducing friction losses, particularly during mixed friction and boundary friction, has been created. Pursuing the practical goal of this research, a new cylinder liner sliding pair of a piston-ring—cylinder (PRC) set (in which the ring has a titanium nitride (TiN) coating and the cylinder liner has a surface layer with varying properties, applied by vacuum nitriding) of a piston packing ring—combustion engine was designed and made. The sliding pair can be used in self-ignition combustion engines and in spark-ignition engines. The sliding pair is the result of the research carried out as part of this paper, including tests in a tribotester and three-stage testing embracing numerical simulations, preliminary tests on the real object, and tests proper on the real object.
Tribology for space applications
Authors: Jones W R , Jansen M J
Published: November 2008

Historically, space mechanism lubricant choices were based on space heritage rather than on the latest technology or best available materials. With the limited mission lives and minimal duty cycles of the early space programme, this strategy was highly successful. As missions extended, other spacecraft components, such as electronics, batteries, and computers, failed before lubricated mechanisms; however, during the 1980s and 1990s, these ancillary components vastly improved and tribological systems became a main factor limiting spacecraft reliability and performance. Although tribological components represent only a small fraction of the spacecraft's cost, they are often single-point failures that cripple or debilitate expensive spacecraft. This paper will discuss the following: common space lubricants, mechanism components, testing, and factors affecting lubricant selections.
Cold welding in hold down points of space mechanisms due to impact and fretting
Authors: Merstallinger A , Sales M , Semerad E , Dunn B D
Published: November 2008

This paper presents an overview of a special vacuum or space related effect, which is referred to as ‘cold welding’, ‘adhesion’, ‘sticking’ or ‘stiction’. These terms refer to ‘welding or sticking’ of contacting bodies, which only open vertically (no sliding), i.e. according to European Cooperation for Space Standardization ‘separable contact surfaces’. Initiated by a reported failure on a spacecraft, test facilities were developed and a verification study was performed to show the relevance between the test results and the reported failure. In the following, a standardized test method was set-up, in order to compare technological levels of different space-relevant materials and coatings for their tendency to cold welding. Since then several studies were performed. Within them, common experience and numerical results were gained on space relevant combinations of materials and coatings with surface states typical for space engineering. Adhesion forces under fretting were found to exceed the loading forces. As an example, nickel containing stainless steels should be avoided. Based on this knowledge, recommendations for use of certain combinations will be drawn. An assessment of coatings for steels and Aluminium (e.g. hard anodizing, Keronite) is given.
Towards the effective solid lubrication of ball bearings operating at high temperature
Authors: Hampson M R , Roberts E W , Cropper M D , Watters R B , Forster D J
Published: November 2008

Several research projects have been completed as part of an ongoing programme of work into solid-lubricated bearings for high-temperature space operation.

Testing of bearings indicated that MoS2 lubrication is effective at high temperature, but highlighted a potential problem with the commonly used material PGM-HT – that it can shrink permanently during initial heating, leading to loss of clearances and high torques. This effect was subsequently measured quantitatively – components have been shown to contract by ∼ 1.5 per cent on heating to 250 °C. A thermal conditioning regime was devised to avoid the problems of shrinkage.

A number of alternatives to conventional cages were also designed, manufactured, and tested. Hybrid cages, with a metal body and inserts made of self-lubricating materials – PGM-HT and SINTIMID 15M-HT, were identified to be an effective option, which avoids problems with conventional cage designs. Toroidal ball separators made of three different self-lubricating materials – PGM-HT, PTFE, and Vespel SP3 – were also designed, manufactured, and tested.
Single-crystalline Gold Nanodisks Prepared by the Shape Transformation under UV Irradiation from Nanoparticles Protected with Discotic Liquid Crystalline Ligands
Authors: Shen Zhongrong , Miyabayashi Keiko , Higashimoto Mami , Shimoda Tatsuya , Miyake Mikio
Published: November 2008

In this paper, we investigated a convenient shape transformation of gold nanoparticles to nanodisks by UV irradiation in chloroform with the aid of protective agents carrying a triphenylene moiety, which absorbs UV energy and plays a role as a mask in directing the deposition of gold atoms at aspecific position.
Control of c-myc mRNA stability by IGF2BP1-associated cytoplasmic RNPs
Authors: Weidensdorfer Doreen , Stöhr Nadine , Baude Anne , Lederer Marcell , Köhn Marcel , Schierhorn Angelika , Buchmeier Sabine , Wahle Elmar , Hüttelmaier Stefan
Published: November 2008

The RNA-binding protein IGF2BP1 (IGF-II mRNA binding protein 1) stabilizes the c-myc RNA by associating with the Coding Region instability Determinant (CRD). If and how other proteins cooperate with IGF2BP1 in promoting stabilization of the c-myc mRNA via the CRD remained elusive. Here, we identify various RNA-binding proteins that associate with IGF2BP1 in an RNA-dependent fashion. Four of these proteins (HNRNPU, SYNCRIP, YBX1, and DHX9) were essential to ensure stabilization of the c-myc mRNA via the CRD. These factors associate with IGF2BP1 in a CRD-dependent manner, co-distribute with IGF2BP1 in non-polysomal fractions comprising c-myc mRNA, and colocalize with IGF2BP1 in the cytoplasm. A selective shift of relative c-myc mRNA levels to the polysomal fraction is observed upon IGF2BP1 knockdown. These findings suggest that IGF2BP1 in complex with at least four proteins promotes CRD-mediated mRNA stabilization. Complex formation at the CRD presumably limits the transfer of c-myc mRNA to the polysomal fraction and subsequent translation-coupled decay.
Kinetic and thermodynamic analysis of the role of start codon/anticodon base pairing during eukaryotic translation initiation
Authors: Kolitz Sarah E. , Takacs Julie E. , Lorsch Jon R.
Published: November 2008

Start codon recognition is a crucial event in the initiation of protein synthesis. To gain insight into the mechanism of start codon recognition in eukaryotes, we used a yeast reconstituted initiation system to isolate the step of Met-tRNAi•eIF2•GTP ternary complex (TC) binding to the 40S subunit. We examined the kinetics and thermodynamics of this step in the presence of base changes in the mRNA start codon and initiator methionyl tRNA anticodon, in order to investigate the effects of base pairing and sequence on the stability of the resulting 43S•mRNA complex. We observed that the formation of three base pairs, rather than their identities, was the key determinant of stability of TC binding, indicating that nothing is inherently special about the sequence AUG for this step. Surprisingly, the rate constant for TC binding to the 40S subunit was strongly codon dependent, whereas the rate constant for TC dissociation from the 43S•mRNA complex was not. The data suggest a model in which, after the initial diffusion-limited encounter of TC with the 40S subunit, the formation of three matching start codon/anticodon base pairs triggers a conformational change that locks the complex into a stable state. This induced-fit mechanism supports the proposal that initiation codon recognition by the 43S complex induces a conformational change from an open state to a closed one that arrests movement along the mRNA.
Deadenylation is a widespread effect of miRNA regulation
Authors: Eulalio Ana , Huntzinger Eric , Nishihara Tadashi , Rehwinkel Jan , Fauser Maria , Izaurralde Elisa
Published: November 2008

miRNAs silence gene expression by repressing translation and/or by promoting mRNA decay. In animal cells, degradation of partially complementary miRNA targets occurs via deadenylation by the CAF1-CCR4-NOT1 deadenylase complex, followed by decapping and subsequent exonucleolytic digestion. To determine how generally miRNAs trigger deadenylation, we compared mRNA expression profiles in D. melanogaster cells depleted of AGO1, CAF1, or NOT1. We show that ∼60% of AGO1 targets are regulated by CAF1 and/or NOT1, indicating that deadenylation is a widespread effect of miRNA regulation. However, neither a poly(A) tail nor mRNA circularization are required for silencing, because mRNAs whose 3′ ends are generated by a self-cleaving ribozyme are also silenced in vivo. We show further that miRNAs trigger mRNA degradation, even when binding by 40S ribosomal subunits is inhibited in cis. These results indicate that miRNAs promote mRNA decay by altering mRNP composition and/or conformation, rather than by directly interfering with the binding and function of ribosomal subunits.
Inventories with Multiple Supply Sources and Networks of Queues with Overflow Bypasses
Authors: Song Jing-Sheng , Zipkin Paul
Published: November 2008

Consider an inventory system with multiple supply sources and Poisson demand. The replenishment lead times from each source are stochastic, representing congestion and disruption. We develop performance evaluation and optimization tools for a family of reasonable order policies. These policies take into account real-time supply information, which can be obtained through tracking technologies such as global positioning systems and radio frequency identification. Performance evaluation of such state-dependent policies is generally hard. The main thrust of this paper is to show that, under these policies, the supply system becomes a network of queues with a special routing mechanism called an overflow bypass. The solution has a simple product form. Thus, we obtain closed-form performance measures. These results reinterpret and extend the existing analysis of a system with two sources having deterministic lead times. We further extend the analysis to batch ordering policies, non-Poisson demand processes, and multiple demand classes.
Asymptotic Optimality of Order-Up-To Policies in Lost Sales Inventory Systems
Authors: Huh Woonghee Tim , Janakiraman Ganesh , Muckstadt John A. , Rusmevichientong Paat
Published: November 2008

We study a single-product single-location inventory system under periodic review, where excess demand is lost and the replenishment lead time is positive. The performance measure of interest is the long-run average holding cost and lost sales penalty cost. For a large class of demand distributions, we show that when the lost sales penalty becomes large compared to the holding cost, the relative difference between the cost of the optimal policy and the best order-up-to policy converges to zero. For any given cost parameters, we establish a bound on this relative difference. Numerical experiments show that the best order-up-to policy performs well, yielding an average cost that is within 1.5% of the optimal cost when the ratio between the lost sales penalty and the holding cost is 100. We also propose a heuristic order-up-to level using two newsvendor expressions; in our experiments, the cost of this order-up-to policy is 2.52% higher, on an average, than the best order-up-to policy.
First Evidence of Multiple Octahedral Al Sites in Na-Montmorillonite by 27Al Multiple Quantum MAS NMR
Authors: Takahashi Takafumi , Kanehashi Koji , Saito Koji
Published: November 2008

The configuration of hydroxyl groups around the octahedral cations of 2:1 phyllosilicate minerals has long been an important question in clay science. In the present study, 27Al multiple quantum (MQ) magic angle spinning nuclear magnetic resonance (MAS NMR) was applied to the local structural analysis of octahedral Al positions in a purified Na-montmorillonite. Three octahedral Al sites ([6]Ala, [6]Alb, and [6]Alc) are distinguished by 27Al 5QMAS NMR, whereas these sites are not differentiated by 27Al MAS and 3QMAS NMR. The isotropic chemical shift (δcs) and the quadrupolar product (PQ) were estimated to be 5.8 ppm and 2.6 MHz for [6]Ala, 6.2 ppm and 3.0 MHz for [6]Alb, and 6.7 ppm and 3.7 MHz for [6]Alc, respectively. The three Al sites originated from geometric isomers with cis and trans structures, which have mutually different configurations of the OH groups around the central Al3+ ions. From the view point of symmetry for the OH groups, [6]Ala and [6]Alb in the upfield region were assigned to cis sites, and [6]Alc in the downfield region was assigned to a trans site. The occurrence of multiple Al sites implies that Na-montmorillonite used in the present study has cis-vacant structure in the octahedral sheet. This is a reasonable insight, supported by the chemical composition and the differential thermal analysis data of the Na-montmorillonite.
Smectite Clay Adsorption of Aflatoxin vs. Octahedral Composition as Indicated by FTIR
Authors: Tenorio Arvide M. G. , Mulder I. , Barrientos Velazquez A. L. , Dixon J. B.
Published: November 2008

The fungus Aspergillus flavus Link ex Fries can infect grains and oil seeds and develop Aflatoxin B1 (AfB1) in the fieldor in storage. Aflatoxin contamination is a serious health hazard — it is extremely toxic and hepatocarcinogenic for animals and humans. A practical approach to solve this problem is to use smectite clay as an amendment to animal feed. The objective of this research is to investigate smectite clay—AfB1 interactions by employing Fourier transform infrared (FTIR) spectroscopy to determine how clay composition influences AfB1 adsorption by smectites. When AfB1 was present in the clay, the spectral region from 1800 to 1300 cm−1 was altered, and the regions between 4000 and 1800 and 1300 and 400 cm−1 were unchanged except for the intensity in the broad region near 3400 cm−1 related to the abundance of water. The 1300–400 cm−1 region is attributed only to smectite clay properties, and it relates to the relative adsorption potential of the different smectites. Bonding between AfB1 and smectite clay appears to be in the furan rings. Other possible bonding is with the two oxygens in the coumarin ring of AfB1 and interlayer cations or their associated water molecules. The FTIR evidence of octahedral Fe in smectite and amorphous silica in the clays both indicate greater AfB1 adsorption potential. Other smectites with spectral absorption indicating predominantly Al in the octahedral positions adsorbed less AfB1.
Something Other than Autobiography: Collaborative Life-Narratives in the Americas—An Introduction
Authors: McHugh Kathleen , Komisaruk Catherine
Published: November 2008

This Introduction to a special essay cluster on "Collaborative Life-Narratives in the Americas" suggests a field of texts and critical practices, arising from the material circumstances of colonialism in the Americas, that counters traditional autobiographical narrative. The essays explore the complicated relationships among literacy, identity, colonialism, and conquest, as the narration of marginalized lives invokes collaboration with technologies of literacy.
Rape Narratives, Rape Silences: Sexual Violence and Judicial Testimony in Colonial Guatemala
Authors: Komisaruk Catherine
Published: November 2008

Using cases documented in the colonial Spanish judicial archives of Central America, this essay considers litigants' depositions as a form of collaborative life-narrative, recorded on paper by government notaries in a court system that functioned according to dominant social ideologies. An analysis of the transcribed narratives of certain rape survivors suggests that other rapes were never recorded. Pointing to the ways that legal culture determined which charges would be brought and which cases would be heard in the courts, Komisaruk illustrates both contested and cooperative collaborations between colonial institutions and colonized subjects. These collaborations produced a historical record of Spanish American life, but also created silences where histories went unrecorded, notably in cases of sexual violence.
"As Gay and as Indian as They Chose": Collaboration and Counter-Ethnography in In the Land of the Grasshopper Song
Authors: Watson Julia
Published: November 2008

This essay illuminates multiple complexities in collaborative life writing through an analysis of In the Land of the Grasshopper Song: Two Women in the Klamath River Indian Country in 1908–09 by Mary Ellicott Arnold and Mabel Reed, a book in the form of a journal recounting colonial contact between whites and indigenous people prior to the 1910 United States appropriation of native lands in what is now far northwestern California. Arnold and Reed function as amateur ethnographers, narrating a complex tale of encounters and negotiations, but they leave out those that had to do with their lesbian relationship. Thus, their overt collaboration masked that of a more private kind. Watson examines the very complicated speaking position(s) of Arnold and Reed in relation to the native population, their white cohort, and each other, illuminating the various modes of collaboration that emerge from this multiply voiced text: co-optation, coercion, collusion, cooperation, collectivity, compromise, and camoufl age.
Profane Illuminations: History and Collaboration in James Luna and Isaac Artenstein's The History of the Luiseño People
Authors: McHugh Kathleen
Published: November 2008

This essay studies narrative collaboration in film, focusing on The History of the Luiseño People , produced collaboratively by performance artist James Luna and filmmaker Isaac Artenstein. The film uses the ephemeral quality of performance art to allegorize the loss of a material history that would register its story. Rather than invoking division, plurality, and ambiguity, Luna and Artenstein limit their film's historical space to the media and the domestic, and its temporality to a version of what Walter Benjamin called "nowtime." Although History 's apparent collaboration with negative stereotypes of Native Americans has angered many critics, McHugh reads the film as an instance of Benjaminian "profane illumination." Her essay details Luna and Artenstein's profane apprehension of the historical, as she considers their strategies within the contexts in which the film was funded, produced, distributed, and exhibited.