bluuebunny/crossref_metadata_2025 huggingface dataset:
Association between the FTO rs9939609 polymorphism and the metabolic syndrome in a non-Caucasian multi-ethnic sample
Authors: Al-Attar Salam A , Pollex Rebecca L , Ban Matthew R , Young T Kue , Bjerregaard Peter , Anand Sonia S , Yusuf Salim , Zinman Bernard , Harris Stewart B , Hanley Anthony JG , Connelly Philip W , Huff Murray W , Hegele Robert A
Published: March 2008

Background

The rs9939609 T>A single-nucleotide polymorphism (SNP) in the FTO gene has previously been found to be associated with obesity in European Caucasian samples. The objective of this study is to examine whether this association extends to metabolic syndrome (MetS) and applies in non-Caucasian samples.

Methods

The FTO rs9939609 SNP was genotyped in 2121 subjects from four different non-Caucasian geographical ancestries. Subjects were classified for the presence or absence of MetS according to the International Diabetes Federation (IDF) and National Cholesterol Education Program Adult Treatment Panel (NCEP ATP) III definitions.

Results

Carriers of ≥ 1 copy of the rs9939609 A allele were significantly more likely to have IDF-defined MetS (35.8%) than non-carriers (31.2%), corresponding to a carrier odds ratio (OR) of 1.23 (95% confidence interval [CI] 1.01 to 1.50), with a similar trend for the NCEP ATP III-defined MetS. Subgroup analysis showed that the association was particularly strong in men. The association was related to a higher proportion of rs9939609 A allele carriers meeting the waist circumference criterion; a higher proportion also met the HDL cholesterol criterion compared with wild-type homozygotes.

Conclusion

Thus, the FTO rs9939609 SNP was associated with an increased risk for MetS in this multi-ethnic sample, confirming that the association extends to non-Caucasian population samples.
The role of neighborhood level socioeconomic characteristics in Salmonella infections in Michigan (1997–2007): Assessment using geographic information system
Authors: Younus Muhammad , Hartwick Edward , Siddiqi Azfar A , Wilkins Melinda , Davies Herbert D , Rahbar Mohammad , Funk Julie , Saeed Mahdi
Published: March 2008

Background:

The majority of U.S. disease surveillance systems contain incomplete information regarding socioeconomic status (SES) indicators like household or family income and educational attainment in case reports, which reduces the usefulness of surveillance data for these parameters. We investigated the association between select SES attributes at the neighborhood level and Salmonella infections in the three most populated counties in Michigan using a geographic information system.

Methods:

We obtained data on income, education, and race from the 2000 U.S. Census, and the aggregate number of laboratory-confirmed cases of salmonellosis (1997–2006) at the block group level from the Michigan Department of Community Health. We used ArcGIS to visualize the distribution, and Poisson regression analysis to study associations between potential predictor variables and Salmonella infections.

Results:

Based on data from 3,419 block groups, our final multivariate model revealed that block groups with lower educational attainment were less commonly represented among cases than their counterparts with higher education levels (< high school degree vs. ≥ college degree: rate ratio (RR) = 0.79, 95% confidence interval (CI):0.63, 0.99; ≥ and high school degree, but no college degree vs. ≥ college degree: RR = 0.84, 95% CI: 0.76, 0.92). Levels of education also showed a dose-response relation with the outcome variable, i.e., decreasing years of education was associated with a decrease in Salmonella infections incidence at the block group level.

Conclusion:

Education plays a significant role in health-seeking behavior at the population level. It is conceivable that a reporting bias may exist due to a greater detection of Salmonella infections among high education block groups compared to low education block groups resulting from differential access to healthcare. In addition, individuals of higher education block groups who also have greater discretionary income may eat outside the home frequently and be more likely to own pets considered reservoirs of Salmonella, which increase the likelihood of contracting Salmonella infections compared to their counterparts with lower levels of education. Public health authorities should focus on improving the level of disease detection and reporting among communities with lower income and education and further evaluate the role of higher educational attainment in the predisposition for salmonellosis.
Targeting Lymph Node Retrieval and Assessment in Stage II Colon Cancer: A Quality Outcome Community-Based Cancer Center Study
Authors: Grote Thomas , Hughes Amy H. , Rimmer Cathy C. , Less Dale A. , Abernethy Amy P. ,   Multidisciplinary Gastrointestinal Tumor Board, Derrick L. Davis Forsyth Regional Cancer Center
Published: March 2008

Purpose

Adequate lymph node evaluation is required for the proper staging of colon cancer. The current recommended number of lymph nodes that should be retrieved and assessed is 12.

Methods

The multidisciplinary Gastrointestinal Tumor Board at the Derrick L. Davis Forsyth Regional Cancer Center reviewed and recommended that a minimum of 12 lymph nodes be examined in all cases of colon cancer to ensure proper staging. This recommendation occurred at the end of the first quarter of 2005. To ensure this new standard was being followed, an outcomes study looking at the number of lymph nodes evaluated in stage II colon cancer was initiated. All patients with stage II colon cancer diagnosed between 2004 and 2006 were reviewed.

Results

There was a statistically significant improvement in the number of stage II colon cancer patients with 12 or more lymph nodes evaluated. Before the Gastrointestinal Tumor Board's recommendation, 49% (40 out of 82 patients) had 12 or more lymph nodes sampled. The median number of lymph nodes evaluated was 11. After the Gastrointestinal Tumor Board's recommendation, 79% (70 out of 88 patients) had 12 or more lymph nodes sampled. The median number of lymph nodes was 16.

Conclusion

Multidisciplinary tumor boards can impact the quality of care of patients as demonstrated in this study. Although we do not yet have survival data on these patients, based on the previous literature referenced in this article, we would expect to see an improvement in survival rates in patients with 12 or more nodes retrieved and assessed.
Effective Cellular Uptake and Efflux of Thyroid Hormone by Human Monocarboxylate Transporter 10
Authors: Friesema Edith C. H. , Jansen Jurgen , Jachtenberg Jan-willem , Visser W. Edward , Kester Monique H. A. , Visser Theo J.
Published: March 2008

Cellular entry of thyroid hormone is mediated by plasma membrane transporters, among others a T-type (aromatic) amino acid transporter. Monocarboxylate transporter 10 (MCT10) has been reported to transport aromatic amino acids but not iodothyronines. Within the MCT family, MCT10 is most homologous to MCT8, which is a very important iodothyronine transporter but does not transport amino acids. In view of this paradox, we decided to reinvestigate the possible transport of thyroid hormone by human (h) MCT10 in comparison with hMCT8. Transfection of COS1 cells with hMCT10 cDNA resulted in 1) the production of an approximately 55 kDa protein located to the plasma membrane as shown by immunoblotting and confocal microscopy, 2) a strong increase in the affinity labeling of intracellular type I deiodinase by N-bromoacetyl-[125I]T3, 3) a marked stimulation of cellular T4 and, particularly, T3 uptake, 4) a significant inhibition of T3 uptake by phenylalanine, tyrosine, and tryptophan of 12.5%, 22.2%, and 51.4%, respectively, and 5) a marked increase in the intracellular deiodination of T4 and T3 by different deiodinases. Cotransfection studies using the cytosolic thyroid hormone-binding protein μ-crystallin (CRYM) indicated that hMCT10 facilitates both cellular uptake and efflux of T4 and T3. In the absence of CRYM, hMCT10 and hMCT8 increased T3 uptake after 5 min incubation up to 4.0- and 1.9-fold, and in the presence of CRYM up to 6.9- and 5.8-fold, respectively. hMCT10 was less active toward T4 than hMCT8. These findings establish that hMCT10 is at least as active a thyroid hormone transporter as hMCT8, and that both transporters facilitate iodothyronine uptake as well as efflux.
Silencing of the Mineralocorticoid Receptor by Ribonucleic Acid Interference in Transgenic Rats Disrupts Endocrine Homeostasis
Authors: Lim Hee-Young , van den Brandt Jens , Fassnacht Martin , Allolio Bruno , Herold Marco J. , Reichardt Holger M.
Published: March 2008

Currently, gene disruption by homologous recombination in embryonic stem cells is only feasible in mice. To circumvent this problem, we silenced mineralocorticoid receptor (MR) expression by RNA interference in knockdown rats generated through lentiviral transgenesis. Analysis of the F1 progeny at 3 wk of age revealed strongly decreased MR levels. This was specific for the targeted gene and related to the abundance of the short interfering RNA. Reminiscent of MR knockout mice, the transgenic rats showed a reduced body weight, elevated serum aldosterone levels, increased plasma renin activity, and altered expression of MR target genes. Some of these effects correlated with the degree to which MR mRNA expression was reduced. Whereas disruption of the MR by gene targeting in mice leads to postnatal death, our strategy also allowed obtaining adult knockdown rats with defects in hormone and electrolyte homeostasis resembling pseudohypoaldosteronism. In conclusion, this is the first example of a human disease model based on RNA interference in rats.
Obestatin Induction of Early-Response Gene Expression in Gastrointestinal and Adipose Tissues and the Mediatory Role of G Protein-Coupled Receptor, GPR39
Authors: Zhang Jian V. , Jahr Holger , Luo Chin-Wei , Klein Cynthia , Van Kolen Kristof , Ver Donck Luc , De Ananya , Baart Esther , Li Jing , Moechars Dieder , Hsueh Aaron J. W.
Published: March 2008

Obestatin was identified as a brain/gut peptide hormone encoded by the ghrelin gene and found to interact with the G protein-coupled receptor, GPR39. We investigated target cells for obestatin based on induction of an early-response gene c-fos in different tissues. After ip injection of obestatin, c-fos staining was found in the nuclei of gastric mucosa, intestinal villi, white adipose tissues, hepatic cords, and kidney tubules. Immunohistochemical analyses using GPR39 antibodies further revealed cytoplasmic staining in these tissues. In cultured 3T3-L1 cells, treatment with obestatin, but not motilin, induced c-fos expression. In these preadipocytes, treatment with obestatin also stimulated ERK1/2 phosphorylation. Because phenotypes of GPR39 null mice are partially consistent with a role of GPR39 in mediating obestatin actions, we hypothesized that inconsistencies on the binding of iodinated obestatin to GPR39 are due to variations in the bioactivity of iodinated obestatin. We obtained monoiodoobestatin after HPLC purification and demonstrated its binding to jejunum, stomach, ileum, pituitary, and white adipose tissue. Furthermore, human embryonic kidney 293T cells transfected with plasmids encoding human or mouse GPR39 or a human GPR39 isoform, but not the ghrelin receptor, exhibited high-affinity binding to monoiodoobestatin. Binding studies using jejunum homogenates and recombinant GPR39 revealed obestatin-specific displacement curves. Furthermore, treatment with obestatin induced c-fos expression in gastric mucosa of wild-type, but not GPR39 null, mice, underscoring a mediating role of this receptor in obestatin actions. The present findings indicate that obestatin is a metabolic hormone capable of binding to GPR39 to regulate the functions of diverse gastrointestinal and adipose tissues.
Effect of obstacles in the road profile on the dynamic response of a vehicle
Authors: Kropáč O , Múčka P
Published: March 2008

The simulation study is aimed at explaining the effect of large obstacles (bumps and potholes) appearing on a road surface on the response of a vehicle passing the obstacle. For the tyre representation, the simplest point-follower model was used. Only the random obstacle modelled by cosine waves of variable height and constant height-to-length ratio was applied. For the traversing vehicle, two models were considered: a planar model of a personal car with a driver and one passenger, and a planar model of a three-axle truck. Vertical accelerations acting on the travelling people and dynamic tyre forces were estimated. In the first part of this paper, the dependences of the extreme values of the vehicle responses when passing an isolated obstacle on the obstacle height and the travel speed were evaluated. In the second part of this paper, the r.m.s. values of the same quantities were evaluated when the vehicle passes a road section with a standard pure random profile on which a number of randomly distributed obstacles were superimposed. The dependences of all quantities in question on the ‘obstacle density’ and on the travel speed were estimated.
Design of parallel-connected epicyclic-type automatic transmissions with two fundamental geared entities
Authors: Hsu C-H , Huang R-H
Published: March 2008

The purpose of this paper is to present a systematic methodology to simplify effectively the design of automatic transmissions by using the concepts of fundamental geared entity and basic gear ratios. An atlas of parallel-connected epicyclic-type automatic transmissions is first enumerated. Next, an effective procedure is developed to synthesize feasible clutching sequences for all the parallel-connected epicyclic gear mechanisms with two fundamental geared entities. Then, the numbers of teeth of gears in each epicyclic gear mechanism are determined by an analytical method. Finally, four alternatives for four-speed automatic transmissions are generated, and the corresponding rotating and band clutches are embodied to the epicyclic gear mechanism to obtain the atlas of four-speed automatic transmissions. The result of this paper shows that three four-speed automatic transmissions can be synthesized from the atlas of parallel-connected epicyclic gear mechanisms with two fundamental geared entities
Characterization of an axle-gear whine sound in a sports utility vehicle and its objective evaluation based on synthetic sound technology and an artificial neural network
Authors: Lee S-K , Kim T G , Lim J T
Published: March 2008

The gear whine sound of an axle system is one of the most important sound qualities in a sports utility vehicle (SUV). Previous work has shown that, because of masking effects, it is difficult to evaluate the gear whine sound objectively by using only the A-weighted sound pressure level. In this paper, the characteristics of the axle-gear whine sound were first investigated on the basis of synthetic sound technology, and a new objective evaluation method for this sound was developed by using sound metrics, which are the psychoacoustic parameters, and the artificial neural network (ANN) used for the modelling of the correlation between objective and subjective evaluation. This model developed by using ANN was applied to the objective evaluation of the axle-gear whine sound for real SUVs and the output of the model was compared with subjective evaluation. The results indicate a good correlation of over 90 per cent between the subjective and objective evaluations.
Variable inertia effects of an engine including piston friction and a crank or gudgeon pin offset
Authors: Guzzomi A L , Hesterman D C , Stone B J
Published: March 2008

In order to obtain greater accuracy in simulation, more sophisticated models are often required. When it comes to the torsional vibration of reciprocating mechanisms the effect of inertia variation is very important. It has been shown that the inclusion of this variation increases model accuracy for both single-cylinder and multi-cylinder engine torsional vibration predictions. Recent work by the present authors has revealed that piston-to-cylinder friction may modify an engine's ‘apparent’ inertia function. Kinematic analysis also shows that the piston side force and the dynamic piston-to-cylinder friction are interdependent. This has implications for engine vibration modelling. Most modern engines employ a gudgeon pin offset, and there is a growing interest in pursuing large crank offsets; hence, the effect of these on inertia variation is also of interest. This paper presents the derivation of the inertia function for a single engine mechanism, including both piston-to-cylinder friction and crank or gudgeon pin offset, and investigates the effect of each through predictions. The effect of crank offset on the variable inertia function is also verified by experiment.
Semi-active control of a passenger vehicle for improved ride and handling
Authors: Tsampardoukas G , Stammers C W , Guglielmino E
Published: March 2008

A theoretical model is developed for the semi-active control of the suspension of a full passenger car using a variable-structure-type algorithm. Skyhook control and variants of balance control (cancelling or adding the dynamic spring forces) are applied via a magnetorheological damper at the front and rear wheels to improve the vehicle ride and handling. The magnetorheological damper is modelled via a Bouc—Wen approach.

The semi-active vehicle response is compared with a passive response. The robustness of control is established by adding noise to the computed sensor inputs, and the loose-wire scenario is also considered. The results show that balance control is a robust algorithm. The magnitude of acceleration reduction (for the human body and head—neck complex) using semi-active control varies with the semi-active approach and vehicle speed (a simulated random road was assumed). At 30m/s the human body acceleration reduction was found to be 70 per cent with skyhook control and 40 per cent with balance control (cancelling the dynamic spring forces).

The handling manoeuvres of the vehicle are presented utilizing BS ISO 3888-1 1999. The handling performance of the vehicle is significantly improved, when balance control by cancelling is applied on the rear dampers only.

Using skyhook control and balance control by adding a spring force to the system it is not possible to improve the handling response of the vehicle.
Modelling of links in a numerical simulation to improve occupant safety during side impact
Authors: Spingler G
Published: March 2008

During side impact, door panels must be designed according to the original equipment manufacturer's passive safety requirements to reach good European New Car Assessment Programme scores. The energy produced during the shock must be absorbed and no fracture of contactable parts should appear. To design the best solution, numerical finite element codes are used and predictability of the calculations is necessary to converge directly to the safest concept. This paper shows a great improvement in the calculation accuracy by modelling the behaviour of links between parts. Polymer rivet and snap behaviours are discussed and a methodology for samples is described. It is now possible to detect and to reinforce design in risk areas with crash simulations to avoid any breakage of the door panel assembly. Finally, a validation of the door panel is highlighted by comparing experimental results and numerical simulation predictions.
Design of the occupant protection system for frontal impact using the axiomatic approach
Authors: Jeon S-K , Shin M-K , Park G-J
Published: March 2008

The functional requirements (FRs) and design equation of a flexible system change in a continuous manner with respect to a variable such as time. An event-driven flexible system is defined as a subcategory of the flexible system in that it changes in a discrete space. A design scenario is developed for the event-driven systems. The design equation for each event should be defined by using the axiomatic approach and the design equations are assembled to form a full design equation. The design equation for each event can be established by sensitivity analysis. In conceptual design, the design order is determined on the basis of the full design equation. Design parameters (DPs) are found to satisfy FRs in sequence. A DP may consist of multiple design variables. In a detailed design, the design variables are determined. The occupant protection system is an event-driven flexible system because the design matrix and its elements change according to the impact speed. The involved devices are designed on the basis of the developed method. FRs at different impact speeds and corresponding DPs are defined. In a detailed design, the full factorial design of experiments is employed for the design variables of the DPs to reduce the injury levels of the occupant. Computer simulation is utilized for evaluation of the injuries. The results are discussed.
Enhanced braking and steering yaw motion controllers with a non-linear observer for improved vehicle stability
Authors: Song Jeonghoon
Published: March 2008

This study proposes two enhanced yaw motion controllers that are modified versions of a braking yaw motion controller (BYMC) and a steering yaw motion controller (SYMC). A BYMC uses an inner rear-wheel braking pressure controller, while an SYMC uses a rear-wheel steering controller. However, neither device can entirely ensure the safety of a vehicle because of the load transfer from the rear to front wheels during braking. Therefore, an enhanced braking yaw motion controller (EBYMC) and an enhanced steering yaw motion controller (ESYMC) are developed, which contain additional outer front-wheel controllers. The performances of the EBYMC and ESYMC are evaluated for various road conditions and steering inputs. They reduce the slip angle and eliminate variation in the lateral acceleration, which increase the controllability, stability, and comfort of the vehicle. A non-linear observer and driver model also produce satisfactory results.
Pressure-loss reduction and velocity-profile improvement in a catalytic converter by a flow deflector
Authors: Hirata K , Oda R , Tanaka S , Tanigawa H , Funaki J
Published: March 2008

In automobile exhaust systems, catalytic converters have become essential in reducing environmental pollution. However, the main components of catalytic converters produce large pressure drops in exhaust systems, which decrease engine power and increase fuel consumption. In addition to the need to reduce pressure loss, the flow passing through the catalytic substrate strate should be as uniform as possible, which provides a uniform thermal distribution and high catalytic conversion efficiency. The goal of the present study is simultaneously to reduce the pressure loss and to improve the flow distribution under spatial constraints. The authors herein propose new types of device and investigate their performances experimentally. Specifically, the possibilities of two types of flow deflector with a shell structure, which are placed inside the diffuser part of the catalytic converter in order to reduce flow separation, were investigated. In addition, using the particle image velocimetry technique and Pitot tube velocimetry, flow features such as the velocity profiles were elucidated. The tested converter has a standard cylindrical ceramic monolith substrate with channels of square cross-section. As a result, the two flow deflectors can reduce the pressure loss by 17 per cent and 22 per cent, compared with a no-deflector converter and can effectively improve the velocity profile.
Statistical engine knock modelling and adaptive control
Authors: Stotsky A A
Published: March 2008

A new statistical concept of the knock control of a spark ignition automotive engine is proposed. The control aim is associated with the statistical hypothesis test which compares the threshold value with the average value of the maximum amplitude of the knock sensor signal at a certain frequency. Achievement of the control aim implies the desired separation between the average value of the maximum amplitude and the target value and hence the desired probability of knock occurrence. This new control concept allows the control algorithm parameters to be connected to the probability of knock occurrence and customer-related data. The regulation error is defined as the difference between the actual and the desired values of the statistic utilized. A control algorithm which is used for minimization of the regulation error realizes a simple count-up—count-down logic.

A new adaptation algorithm for the knock detection threshold is developed. The confidence interval method is used as the basis for adaptation. A knock detection threshold is presented using a confidence interval with a certain significance level. The adaptation is performed for an aged engine so that the significance level is the same for the new and the aged engines despite the fact that the detection threshold values are different. This, in turn, guarantees the same knock detection performance for new and aged engines.

A simple statistical model which includes generation of the amplitude signals, threshold value determination, and a knock sound model is developed for evaluation of the control concept. The statistical knock audibility concept is associated with the outlier detection method and is used in this paper for knock audibility judgement.

A Volvo six-cylinder prototype engine equipped with cylinder pressure and block vibration sensors was used in the experiments. An external microphone was used for the knock sound measurements.
Challenges and obstacles in the application of acoustic emission to process machinery
Authors: Sikorska J Z , Mba D
Published: March 2008

Managing asset integrity is crucial for the cost-effective asset management of processing plants. Consequently, new techniques for detection and classification of incipient faults are continuously being sought by industry and developed by research and development professionals, both corporate and academic. Although acoustic emission (AE) testing for faults in static equipment has been used since the 1970s, its use as a monitoring technology for various machinery conditions has been poorly adopted by industry, despite a significant volume of work having been published over the past twenty years describing success in detecting numerous rotating and reciprocating machinery faults. Anecdotal evidence from industry suggests that many ‘tried and failed’. The authors believe that this is because applying AE monitoring to industrial plant is fraught with poorly documented challenges, obstacles, and limitations that must be well understood and overcome before any reported results can be replicated. Thus, to enable potential users to approach AE monitoring with more realistic expectations, the current paper discusses several such problems and suggests some available techniques for their management. After an initial introduction on the basics of AE specifically applied to machinery monitoring, issues are divided into generic problems and application-specific challenges.
Discharge coefficient equation of a segmental wedge flowmeter
Authors: Yoon J. Y. , Sung N. W. , Lee C. H.
Published: March 2008

The discharge coefficient is reported for a flowmeter based on a segmental wedge device having a vertex angle of 90° for varying ratios of pipe diameter D to characteristic free flow dimension H at the wedge. The current work suggests that the segmental wedge makes a reliable flow-metering device, with a near constant discharge coefficient over a wide range of Reynolds numbers. A correlation is provided for the discharge coefficient as a function of H/ D.
Optimization of the eccentric check butterfly valve considering the flow characteristics and structural safety
Authors: Yi S I , Shin M K , Shin M S , Yoon J Y , Park G J
Published: March 2008

The eccentric check butterfly valve is a butterfly valve that has an eccentric rotating axis. It is not only used as a butterfly valve to control the flowrate or pressure, but also as a check valve to prevent backward flow. A new design process is proposed for designing the valve. First, an optimization problem with a characteristic function is formulated to determine the amount of eccentricity. The characteristic function to be minimized is defined for the flow characteristics. Second, the waterhammer pressure of the valve disc is calculated by waterhammer analysis when the flow stops suddenly. Structural analysis is carried out to evaluate the waterhammer pressure of the valve disc and structural safety. Structural optimization is performed considering the structural safety and the flow characteristics. The process of structural optimization has two steps: topology optimization and shape optimization. Mass distribution of the disc housing is determined using topology optimization. Since topology optimization does not give the final dimensions, shape optimization is utilized to determine the details based on the results of topology optimization. A light design is derived to satisfy the structural safety and the flow characteristics.
Determination of membrane resistance for cross-flow microfiltration in a rectangular module including back-flow
Authors: Wattananusorn S
Published: March 2008

In the current note, the previously developed semiempirical models are incorporated, based on blocking filtration laws, with an approach by using a higher-order pressure function over the membrane surface providing the local non-linear characteristic of the transmembrane pressure during discontinuous semibatch processes. Consequently, the flux predictions of a continuous cross-flow microfiltration system with back-flow across a membrane module are appropriately modified for more accurate formulations of membrane resistance.
Cooling load and co-efficient of performance optimizations for a generalized irreversible Carnot refrigerator with heat transfer law q ∞ (ΔTn)m
Authors: Li J. , Chen L. , Sun F.
Published: March 2008

The fundamental optimal relation between cooling load and coefficient of performance (COP) of a generalized irreversible Carnot refrigerator is derived based on a new generalized heat transfer law, including generalized convective heat transfer law and generalized radiative heat transfer law, q ∞ (Δ T n) m. The generalized irreversible Carnot refrigerator model incorporates several internal and external irreversibilities, such as heat resistance, bypass heat leakage, friction, turbulence, and other undesirable irreversibility factors. The added irreversibilities besides heat resistance are characterized by a constant parameter and a constant coefficient. The effects of heat transfer laws and various loss terms on the performance of the generalized irreversible Carnot refrigerator are analysed. The obtained results include those obtained in many literatures.
Stall inception in a transonic axial fan
Authors: Khaleghi H , Boroomand M , Tousi A M , Teixeira J A
Published: March 2008

The current paper reports a numerical investigation of stall inception in a transonic compressor rotor, NASA Rotor-67, by using the whole flow passages in the computations. Surface roughness is added to one of the blades in order to trigger rotating stall. During stall inception, the tip clearance vortex moved away from the suction surface of the roughened blade's upper neighbour, leading to vortex breakdown. The stall cell was found to propagate opposite the direction of the blade rotation at about 30 per cent of rotational speed. The effect of air bleeding on stabilizing the compressor is also studied in this work. The mean mass flowrate removed from the bleed valves was ∼1.2 per cent of the mainstream flowrate. This amount of bleeding was found to effectively suppress the stalling disturbances.
Microscopic geometry changes of a direct-injection diesel injector nozzle due to abrasive flow machining and a numerical investigation of its effects on engine performance and emissions
Authors: Jung D , Wang W L , Hu S J
Published: March 2008

The geometric effects of the abrasive flow machining (AFM), a surface finishing process, on a direct-injection diesel fuel injector nozzle are studied and characterized in this study. To measure the microscopic variations inside the nozzle, before and after the AFM process, several different geometry characterization techniques are used. Empirical correlations that relate nozzle geometrical changes to the AFM process period are derived from the measurements. The resulting impact of the geometric changes of the nozzle on the engine performance and emissions are also assessed with a numerical engine cycle simulation model that is based on a quasi-dimensional multi-zone diesel spray combustion model.

This study shows that properly AFM-processed injectors can enhance the engine performance and improve the emissions due to the improved quality of the nozzle characteristics. However, extended process can also cause the enlargement of the nozzle as a side effect and this can adversely affect emissions. Since the enlargement of the nozzle is unavoidable, yet must be minimized, strict control over the process is required. This control can be enforced by either limiting the AFM process, or properly preparing the initial nozzle diameter so as to accommodate the inevitable changes of nozzle geometry.
Performance of the photovoltaic solar-assisted heat pump system with and without glass cover in winter: A comparative analysis
Authors: Pei G , Ji J , Chow T-T , He H , Liu K , Yi H
Published: March 2008

An application of photovoltaic/thermal (PV/T) technology in heat pump, known as the PV solar-assisted heat pump (PV-SAHP) system, is presented. Comparative performance tests were conducted through an experimental rig under two different working conditions of the PV/T collectors: with and without glass cover. The energy performance in terms of PV/photothermic conversions and refrigeration cycle was compared in typical winter days of the temperate climate zone in China. It was found that with a single glass cover, the exergy efficiencies of PV/photothermic conversions and overall PV/T conversion were, respectively, 12.83, 5.26, and 18.09 per cent, and the heat pump coefficient of performance (COP) was 4.85. Without the glass cover, the exergy efficiencies and COP were 13.36, 3.04, and 16.40 per cent, and 3.41, respectively. The results imply that although the presence of the glass cover leads to a small reduction in the PV exergy efficiency, it is able to improve considerably the photothermic exergy efficiency, the overall PV/T exergy efficiency, and the COP of the PV-SAHP system in winter.
A numerical study of the effects of injection velocity on stability improvement in high-speed compressors
Authors: Khaleghi H , Boroomand M , Teixeira J A , Tousi A M
Published: March 2008

The current paper presents numerical simulations for a high-speed axial-flow compressor rotor, NASA Rotor-67, with continuous air injection upstream of the rotor. A parametric study relating injection velocity to compressor stability is undertaken. The effects of injector exit velocity on blade loading and flow field are investigated and discussed. Results indicate that the injection velocity has major effects on compressor stability. The injector effectiveness is found to be maximized when the injector exit Mach number is equivalent to unity. Significant range extension in terms of reduction in stalling flow coefficient equivalent to 13.23 per cent is obtained for the case of choked injector, whereas the injection mass flow is only a small percentage of the main flowrate.
Effects of the low Reynolds number on the loss characteristics in an axial compressor
Authors: Choi M , Baek J H , Chung H T , Oh S H , Ko H Y
Published: March 2008

As the gas turbine becomes smaller and is operated at high altitude, the aerodynamic condition frequently lies at the low Reynolds number. In the present study, three-dimensional computations were performed to understand the effects of the low Reynolds number on the loss characteristics in an axial compressor. The numerical results showed that the performance of the axial compressor like the static pressure rise is reduced by the full-span separation on the suction surface and the boundary layer on the hub, caused by the low Reynolds number. Compared with that at the reference Reynolds number, the total pressure loss at the low Reynolds number was found to be greater from the hub to 85 per cent span and smaller above the 85 per cent span. For a detailed analysis, the total pressure loss was scrutinized through three major loss categories available in the subsonic axial compressor: profile loss, tip leakage loss, and endwall loss.
A Constant Approximation Algorithm for the One-Warehouse Multiretailer Problem
Authors: Levi Retsef , Roundy Robin , Shmoys David , Sviridenko Maxim
Published: March 2008

Deterministic inventory theory provides streamlined optimization models that attempt to capture trade-offs in managing the flow of goods through a supply chain. We will consider two well-studied deterministic inventory models, called the one-warehouse multiretailer (OWMR) problem and its special case the joint replenishment problem (JRP), and give approximation algorithms with worst-case performance guarantees. That is, for each instance of the problem, our algorithm produces a solution with cost that is guaranteed to be at most 1.8 times the optimal cost; this is called a 1.8-approximation algorithm. Our results are based on an LP-rounding approach; we provide the first constant approximation algorithm for the OWMR problem and improve the previous results for the JRP.
Natural language versus the literary standard from Varro to Saussure
Authors: Joseph John E
Published: March 2008

From ancient through modern times there have persisted various versions of a dichotomy between ‘natural’ and other, implicitly ‘unnatural’ forms of language. One version is a split between natural language and an ‘artificial’ literary or standard language. This paper examines several key moments in the development of this particular dichotomy, starting with Varro's belief that the language of poets should not be subject to the same rules of analogy as ordinary language is. Dante sets the pattern for modern considerations of the literary and standard language, which he would create by instituting a reversal of history. The concept is subsequently politicized by, for example, Nebrixa and Du Bellay. Saussure's views on literary language have parallels with Dante's ‘elimination of history’, and resonance for other aspects of Saussure's theory of language. The implications for contemporary views of what is and is not ‘natural’ in language are also considered.
Fictions, fantasies, and fears: The literary foundations of the cl oning debate
Authors: Nerlich Brigitte , Clarke David D , Dingwall Robert
Published: March 2008

The debate about cloning and genetic engineering, which began in 1997, has been strongly influenced by fictional narratives, scripts, and images. They in turn provided the seeds for the creation of various metaphors used in the debate, especially by the media. The flow of metaphors and images associated with cloning is now ebbing away and is being replaced by a new wave of images and metaphors deployed in arguments against genetically modified food. In both cases, cloning and genetically modified food, the media reports are interwoven with more or less explicit references to science fiction novels and films, from Frankenstein to Gattaca and beyond. They nourish and reflect the general public's fears about an increasing process of biological hybridisation which blurs the boundaries between humans, plants, animals, and machines and threatens people's sense of humanity.
Histoire(s) Du Cinéma
Authors: Williams James S.
Published: March 2008

This essay reviews the DVD boxed set of Jean-Luc Godard's experimental, philosophical, argumentative video essay on the history of film and the twentieth century. The essay stresses Godard's remarkable use of montage to create new and provocative juxtapositions that carry unique emotional, historical, and political charge.
Spiraling Downward: America in Days of Heaven, In the Valley of Elah, and No Country for Old Men
Authors: Mellen Joan
Published: March 2008

Bringing together the DVD reissue of Terrence Malick's Days of Heaven, Paul Haggis's In the Valley of Elah, and Joel and Ethan Coen's No Country for Old Men, this essay argues that the three films are indictments of the violent history of American militarism.
Paris Nous Appartient: Flânerie in Paris and Film
Authors: Rollet Brigitte
Published: March 2008

This essay deals with a number of Parisian film institutions as well as cinematic representations of the French capital, noting especially the way the city is depicted in recent films made by women.
Melt-infiltration processing of TiC/Ni3Al composites
Authors: Plucknett K. P. , Becher P. F. , Subramanian R.
Published: March 2008

A simple melt-infiltration processing route has been developed for the fabrication of TiC/Ni3Al ceramic/intermetallic composites, which involves a combination of infiltration and subsequent liquid phase sintering. For Ni3Al contents from 8 to 25 vol. %, densities in excess of 98% of theoretical are readily obtained when processing at 1450 °C. TiC and Ni3Al are the only phases detected in the densified materials. Ni3Al ductility is retained after processing, leading to the possibility of ductile phase toughened TiC composites for elevated temperature applications (up to ∼1100 °C).
Growth of high-quality Bi2Sr2CaCu2Oz crystal and characterization
Authors: Faqir H. , Vacquier G. , Chiba H. , Kikuchi M. , Muraoka Y. , Syono Y.
Published: March 2008

We report growth of high-quality Bi2Sr2CaCu2Oz single crystals with dimensions 2 × 1 × 0.03 mm3 with a melt and growth technique. The composition of this crystal is homogeneous and very close to the stoichiometric composition. Structure characterization of a single crystal was realized by measuring the (001) x-ray diffraction. The lattice parameters of a typical crystal are a = 5.414(2) Å, b = 5.413(2) Å, and c = 30.823(10) Å. The superconducting temperature Tc = 95 K with a sharp transition width (10–90% level) between 6 and 10 K was determined from resistivity and dc susceptibility. We have measured the magnetization of Bi2Sr2CaCu2Oz single crystal under magnetic field applied along the c-axis. The anomalous second peak effect appeared between 20 and 30 K. We discuss the qualities of these crystals.
Phase identification and superconductivity transitions in Sr-doped Pr1.85Ce0.15CuO4+δ
Authors: Varela A. , Vallet-Regí M. , González-Calbet J. M.
Published: March 2008

Sr-doped Pr1.85Ce0.15CuO4+δ samples have been prepared with accurate control of the oxygen content. The stability of both T′ and T* phases is strongly dependent on Sr and oxygen content. An electron diffraction study indicates that, in some cases, anionic vacancies are ordered leading to a pseudo-tetragonal superlattice with unit cell parameters . Structural transitions and superconducting phases created by hole doping in such a system are also reported.
Scanning tunneling microscope study of polyacrylonitrile-based carbon fibers
Authors: Shi Dongxia , Liu Ning , Yang Haiqiang , Gao Juning , Jiang Yueshan , Pang Shijin , Wu Xubiao , Ji Zhen
Published: March 2008

Scanning tunneling microscopy (STM) was used to characterize the surface topography of polyacrylonitrile (PAN)-based carbon fibers before and after electrochemical treatment, stretch resistance test, and high-temperature treatment. A new kind of spiral structures was found, which was not only on the surface but also in the inner layer. The spiral structure of the fibers was caused by the spinning process. The fiber structure contained the shape of the precursor. There were some large cracks in the carbon fibers after the stretching resistance test. The large cracks can result in carbon fiber breaking under certain stress conditions. The difference in the structures of the carbon fibers before and after the high-temperature treatment was determined.
Fatigue crack initiation at Nd-rich particles in an Nd containing high temperature titanium alloy
Authors: Lei J. F. , Wang Q. J. , Liu Y. Y. , Guan S. X. , Wang Z. G. , Li D. , Hu Z. Q.
Published: March 2008

Scanning electron microscopy (SEM) and surface replica method have been employed to study the micromechanism of fatigue crack initiation at Nd-rich phase particles in a high temperature titanium (Ti-55) alloy. It was found that the microcrack initiates near the equator of Nd-rich particles in the matrix. The microcrack grows first at an angle of about 45° with respect to the tensile axis, and then its growth direction becomes approximately normal to the tensile axis. The experimental results are analyzed in terms of the elastic stress distribution around soft particles imbedded in the matrix to account for the experimental findings of particle cracking and the associated surface microcrack initiation near the particle “equator.” A model of fatigue crack initiation at a soft surface particle is proposed.
A structural study of amorphous alkoxide-derived lead titanium complexes
Authors: Malič Barbara , Arčon Iztok , Kosec Marija , Kodre Alojz
Published: March 2008

We studied amorphous lead titanium alkoxide-derived heterometallic complexes, prepared from lead acetate and titanium n-propoxide or n-butoxide in parent alcohol medium. According to gas-liquid chromatography (GLC) and thermogravimetric analysis with mass spectrometry of evolved species (TGA/EGA) analyses, the type of alkoxide group influences oxo or acetate bridging, as well as the amounts of hydroxyl and organic groups bound to the metal network. From XANES and EXAFS analysis, local environments of lead and titanium atoms were determined within the analyzed range of 3.4 Å. Local environments depend weakly on the type of alkoxide used. Titanium atoms are pentacoordinated. A Pb–Ti correlation is established with lead atoms bound to titanium atoms by oxygen linkages.
Domain structures in Pb(Zr, Ti)O3 and PbTiO3 thin films
Authors: Madsen L. D. , Griswold E. M. , Weaver L.
Published: March 2008

The microstructure of Pb(Zr, Ti)O3 (PZT) and PbTiO3 (PT) thin films deposited by the sol-gel method and chemical vapor deposition, respectively, were examined by transmission electron microscopy (TEM). Domains with ∼7 and ∼20 nm widths were found for the PZT and PT thin films, respectively. The traditional parallel twin or wedge-type structures found in bulk ceramics have been observed in thin films. Differences between observed grain sizes and previous studies of similar compounds (in bulk form) are accounted for by geometrical considerations related to crystallographic factors. Finally, a classification scheme for domains in PZT and PT thin films based on these and other published results of several researchers is presented. Domain sizes varied according to three categories: mono-domains (2–50 nm in diameter), domains in spherulite lamellae (28–130 nm wide), and twins in conventional large grains (5–150 nm wide). The mono-domains are related to small grain sizes, while the lamellae are a function of the nucleation and growth associated with sol-gel processing.
Estimation of Weibull parameter with a modified weight function
Authors: Chandrasekhar B. K.
Published: March 2008

The Weibull modulus is widely used for estimating the reliability of ceramic components in engineering applications. An improvement in the evaluation of the Weibull modulus is achieved by using an appropriate weight function to the data points while fitting a straight line to the Weibull plot by the least square method. The conventional weight function is a function of the probability of failure. This paper describes an alternate method of obtaining the weight function based on first principles. This modified weight function is a function of the stress at failure rather than probability of failure. Evaluation of the two-parameter Weibull modulus was estimated on simulated strength distribution data with both the weight functions. A comparative analysis indicates that the modified weight function gives a different result than the conventional weight function. The paper also highlights the effect and importance of uncertainties in the measurement of strength on the calculated Weibull modulus.