bluuebunny/crossref_metadata_2025 huggingface dataset:
American Association on Mental Retardation'sDefinition, Classification, and System of Supportsand Its Relation to International Trends and Issues in the Field of Intellectual Disabilities
Authors: Schalock Robert L. , Luckasson Ruth
Published: February 2005

Abstract This article provides an overview of the 2002 American Association on Mental Retardation's (AAMR’s)Definition, Classification, and Systems of Supports(the 2002 System) and discusses its relationship to salient international trends and several scientific and judgmental issues currently impacting the field of intellectual disabilities (ID). Five significant international trends – ecologic perspective, disablement as a limitation in functioning, multidimensionality of ID, linking assessment to intervention, and the importance of clinical judgment – are identified and related to the 2002 System. The scientific and policy issues which impact definitional, classification, and intervention systems include: distinguishing among naming, defining, and classifying; answering the question, “what is a disability?”; delineating the essential characteristics of the condition; determining the relationship between intelligence and adaptive behavior; and defining the class. The 2002 System is critiqued and discussed within the contemporary context of thinking about and supporting people with ID. The authors conclude that time will tell how effective the 2002 AAMR System is in meeting the challenge of defining the framework of ID and providing a universally applicable and effective model for the diagnosis, classification, and planning of supports for persons with ID.
Impact of Copayment Requirements on Therapy Utilization for Children with Developmental Disabilities in Israeli Jewish and Arab Bedouin Populations
Authors: Lubetzky Hasia , Shvarts Shifra , Galil Aharon , Tesler Hedva , Vardi Gideon , Merrick Joav
Published: February 2005

Abstract  Under Israeli law, national health insurance covers basic health care for all of the nation's residents, but health services users have to copay for medications and therapy. This study examined whether the requirement to copay for therapy services among certain subpopulations influences their compliance with meeting rehabilitation therapy appointments for their children with intellectual and other disabilities. The study population included 6,249 Israeli Jewish children and 2,255 Arab Bedouin children from southern Israel, who were scheduled for appointments at the Zussman Child Development Center (ZCDC) in Beer‐Sheva during the period from January 1995 to December 1999. Data were examined to determine the relationship between “rate of noncompliance” and the patients’ ethnicity, the rehabilitation service offered, and the periods 1995–97 (prior to copayment requirement) vs. 1998–99 (after the requirement of copayment). A 37% increase in risk for noncompliance with therapy appointments was found for the Arab Bedouins, in comparison with the rate of noncompliance with therapy among Israeli Jews. The results indicate that the legislation requiring copayment appears to have had a negative impact on the use of rehabilitation services for children with disabilities, as cultural and economic condition factors were not taken into consideration with the copayment requirement.
Applying the Self‐Determination Theory to Japanese Special Education Contexts: A Four‐Step Model
Authors: Ohtake Yoshihisa , Wehmeyer Michael L.
Published: February 2005

Abstract  The authors describe what preparations they undertook before introducing self‐determination theory and its corresponding teaching model to the Japanese special education system for students with intellectual disabilities. The Japanese special education services are designed to nurture students to be individuals who are independent, know and exhibit preferences and interests, set and achieve goals, and possess a sense of achievement and self‐awareness. In this respect, the values embedded in the practices of the prevalent Japanese special education teaching model appear to substantially overlap with those of self‐determination. At the same time, Japanese education is designed to value corporate independence, corporate preferences and interests, setting and achieving corporate goals, and corporate sense of achievement and self‐awareness. The authors conclude that by focusing on these similarities when introducing the concepts and strategies underlying self‐determination to Japanese professionals it will help them operationalize what they have done, what they have tried to do, and what they are going to do. Further, by substituting the term “self” determination for “corporate” determination, the functional model of self‐determination and the corresponding teaching model can be applied to theorize or articulate the practices of Japanese special education that have been implemented on the basis of collectivism values.
Findings from a Court Study of Care Proceedings Involving Parents with Intellectual Disabilities
Authors: Booth Tim , Booth Wendy
Published: February 2005

Abstract  This report summarizes the findings of a study of court files relating to care proceedings involving parents with an intellectual disability. The authors found that 15.3% of all children subject to care applications in the year 2000 in the courts studied had at least one parent with an intellectual disability. They also found that these children were less likely to be returned home and more likely to be freed for adoption than the children of any other group of parents. The data raise questions about the discriminatory treatment of parents with an intellectual disability in the child protection process.
Neurovascular responses to mental stress
Authors: Carter Jason R. , Kupiers Nathan T. , Ray Chester A.
Published: February 2005

The effects of mental stress (MS) on muscle sympathetic nerve activity (MSNA) and limb blood flows have been studied independently in the arm and leg, but they have not been studied collectively. Furthermore, the cardiovascular implications of postmental stress responses have not been thoroughly addressed. The purpose of the current investigation was to comprehensively examine concurrent neural and vascular responses during and after mental stress in both limbs. In Study 1, MSNA, blood flow (plethysmography), mean arterial pressure (MAP) and heart rate (HR) were measured in both the arm and leg in 12 healthy subjects during and after MS (5 min of mental arithmetic). MS significantly increased MAP (Δ15 ± 3 mmHg; P < 0.01) and HR (Δ19 ± 3 beats min−1; P < 0.01), but did not change MSNA in the arm (14 ± 3 to 16 ± 3 bursts min−1; n= 6) or leg (14 ± 2 to 15 ± 2 bursts min−1; n= 8). MS decreased forearm vascular resistance (FVR) by −27 ± 7% (P < 0.01; n= 8), while calf vascular resistance (CVR) did not change (−6 ± 5%; n= 11). FVR returned to baseline during recovery, whereas MSNA significantly increased in the arm (21 ± 3 bursts min−1; P < 0.01) and leg (19 ± 3 bursts min−1; P < 0.03). In Study 2, forearm and calf blood flows were measured in an additional 10 subjects using Doppler ultrasound. MS decreased FVR (−27 ± 10%; P < 0.02), but did not change CVR (5 ± 14%) as in Study 1. These findings demonstrate differential vascular control of the arm and leg during MS that is not associated with muscle sympathetic outflow. Additionally, the robust increase in MSNA during recovery may have acute and chronic cardiovascular implications.
A Review of Some Early Design Practice Using Computational Fluid Dynamics and a Current Perspective
Authors: Horlock J. H. , Denton J. D.
Published: February 2005

In the early development of gas turbines, many empirical design rules were used; for example in obtaining fluid deflection using the deviation from blading angles, in the assumption of zero radial velocities (so-called radial equilibrium) and in expressions for clearance loss (the Lakshminarayana formulas). The validity of some of these rules, and the basic fluid mechanics behind them, is examined by use of modern ideas and computational fluid dynamics (CFD) codes. A current perspective of CFD in design is given, together with a view on future developments.
Calculating the Eigenfrequency of Rotating Acoustic Annulus Inside Labyrinth Seals of Turbomachines
Authors: Hurlebaus Stefan , Gaul Lothar
Published: February 2005

This brief note describes a method for calculating the eigenfrequencies of a rotating acoustic air column inside labyrinth seals in turbomachinery. The method is applied to nonrotating air columns as well as to rotating air columns considering a body fixed and a spatial fixed coordinate system.
A Multistage Compressor Test Facility: Uncertainty Analysis and Preliminary Test Results
Authors: Bettocchi R. , Pinelli M. , Spina P. R.
Published: February 2005

A multistage compressor test facility, fully instrumented with a dedicated data acquisition and processing system, has been developed to conduct experimental research work at the University of Ferrara. This paper provides a systematic description of the uncertainty analysis procedures required for compressor testing, including preliminary performance test results, in addition to a brief description of the test facility and its capabilities.
A Study of Humidified Gas Turbines for Short-Term Realization in Midsized Power Generation—Part I: Nonintercooled Cycle Analysis
Authors: Bartlett Michael A. , Westermark Mats O.
Published: February 2005

Humidified Gas Turbine (HGT) cycles are a group of advanced gas turbine cycles that use water-air mixtures as the working media. In this article, three known HGT configurations are examined in the context of short-term realization for small to midsized power generation: the Steam Injected Gas Turbine, the Full-flow Evaporative Gas Turbine, and the Part-flow Evaporative Gas Turbine. The heat recovery characteristics and performance potential of these three cycles are assessed, with and without intercooling, and a preliminary economic analysis is carried out for the most promising cycles.
Flame Ionization Sensor Integrated Into a Gas Turbine Fuel Nozzle
Authors: Benson Kelly , Thornton Jimmy D. , Straub Douglas L. , Huckaby E. David , Richards Geo. A.
Published: February 2005

Recent advances in lean premix gas turbine combustion have focused primarily on increasing thermodynamic efficiency, reducing emissions, and minimizing combustion dynamics. The practical limitation on increasing efficiency at lower emissions is the onset of combustion instability, which is known to occur near the lean flammability limit. In a laboratory environment there are many sensors available that provide the combustion engineer with adequate information about flame stability, but those sensors are generally too expensive or unreliable for widespread application in the field. As a consequence, engines must be commissioned in the field with adequate stability margin such that normally expected component wear, fuel quality, and environmental conditions will not cause the turbine to experience unstable combustion. Woodward Industrial Controls, in cooperation with the National Energy Technology Laboratory, is developing a novel combustion sensor that is integrated into the fuel nozzle such that low cost and long life are achieved. The sensor monitors flame ionization, which is indicative of air–fuel ratio and most importantly flame stability.
Review of Centrifugal Compressor’s Application and Development
Authors: Krain Hartmut
Published: February 2005

The paper historically describes the application and development of the centrifugal compressor from the very beginning of its introduction until today. It focuses on selected practical and theoretical examples that—to the author’s opinion—pushed the centrifugal’s standard from simple, low efficiency designs to its current high level status. The main events related with this development like the impact of the industrial revolution and the introduction of jet propulsion are pointed out. The implication of improved theoretical tools becoming available with raising computer capacity and the impetus of advanced measurement techniques on the centrifugal’s improvement are described. A considerable number of references offers the possibility to engross the thoughts.
Main Bearing Friction and Thermal Interaction During the Early Seconds of Cold Engine Operation
Authors: Shayler Paul J. , Baylis Warren S. , Murphy Michael
Published: February 2005

Motoring tests have been carried out on an unloaded crankshaft to examine friction levels and the influence of local thermal conditions in and around the main bearings, at speeds covering the range of 200–1000 rev/min and from initial temperatures down to −20°C. The temperatures of the bearing oil film and the adjacent metal are strongly coupled. This directly influences the variation of friction with time during the early seconds of running. The possibility of lowering friction during this period by reducing the strength of the thermal coupling has been investigated. Heat conduction through the bearing shells can be reduced by raising the contact resistance at the rear surface of the shells, raising oil film temperature, and hence, reducing local oil viscosity. Experimental data and model predictions illustrate that a significant reduction in bearing friction can be achieved.
Systematic Assessment of Combustion Turbine Inlet Air-Cooling Techniques
Authors: Al-Amiri Abdalla M. , Zamzam Montaser M.
Published: February 2005

The current study is centered on assessing the benefits of incorporating combustion turbine inlet air-cooling systems into a reference combustion turbine plant, which is based on a simple cycle under base load mode. Actual climatic conditions of a selected site were examined thoroughly to identify the different governing weather patterns. The main performance characteristics of both refrigerative and evaporative cooling systems were explored by examining the effect of several parameters including inlet air temperature, airflow-to-turbine output ratio, coefficient of performance (for refrigerative cooling systems), and evaporative degree hours (for evaporative cooling systems). The impact of these parameters was presented against the annual gross energy increase, average heat rate reduction, cooling load requirements and net power increase. Finally, a feasibility design chart was constructed to outline the economic returns of employing a refrigerative cooling unit against different prescribed inlet air temperature values using a wide range of combustion turbine mass flow rates.
Transfer Function Calculations for Aeroengine Combustion Oscillations
Authors: Zhu M. , Dowling A. P. , Bray K. N. C.
Published: February 2005

Combustors with fuel-spray atomizers are particularly susceptible to a low-frequency oscillation at idle and subidle conditions. For aeroengine combustors, the frequency of this oscillation is typically in the range 50–120 Hz and is commonly called “rumble.” The mechanism involves interaction between the plenum around the burner and the combustion chamber. Pressure variations in the plenum or the combustor alter the inlet air and fuel spray characteristics, thereby changing the rate of combustion. This in turn leads to local “hot spots” which generate pressure oscillations as they convect through the downstream nozzle. In order to eliminate the combustion oscillations, it is essential to determine which fuel atomizers are particularly likely to lead to instability by quantifying their sensitivity to flow perturbations. This can be done by identifying the system through understanding the transfer function, which represents the relationship between the unsteadiness of combustion and the inlet fuel and air. In the present work, various types of signals are applied to produce a small change in the inlet fuel and air flow rates, the response in the rate of heat release caused downstream was calculated and stored for subsequent analysis. Afterwards, the system transfer function is calculated by determining the coefficients of an IIR filter (Infinite Impulse Response) for which the output signal is the downstream heat release rate and the input signal is the inlet flow rate. The required transfer function then follows from the Fourier transform of this relationship. The resulting transfer functions are compared with those obtained by the forced harmonic oscillations at a fixed given frequency. Suitably chosen input signals accurately recover the results for harmonic forcing at a single frequency, but also give detailed information about the combustor response over a wide frequency range. There are two distinct forms to the low-frequency quasisteady response. In the primary zone, the rate of combustion is influenced by the turbulence and is enhanced when the inlet air velocity is large. Near the edge of combustion zone, the rate of combustion depends on the mixture fraction and is high when the mixture fraction is close to the stoichiometric value. This generates ‘hot spots’ which convect into the dilution zone. At higher frequencies, the combustion lags this quasi-steady response through simple lag-laws and the relevant time delays have been identified.
A Flight Simulation Vision for Aeropropulsion Altitude Ground Test Facilities
Authors: Davis Milt , Montgomery Peter
Published: February 2005

Testing of a gas turbine engine for aircraft propulsion applications may be conducted in the actual aircraft or in a ground-test environment. Ground test facilities simulate flight conditions by providing airflow at pressures and temperatures experienced during flight. Flight-testing of the full aircraft system provides the best means of obtaining the exact environment that the propulsion system must operate in but must deal with limitations in the amount and type of instrumentation that can be put on-board the aircraft. Due to this limitation, engine performance may not be fully characterized. On the other hand, ground-test simulation provides the ability to enhance the instrumentation set such that engine performance can be fully quantified. However, the current ground-test methodology only simulates the flight environment thus placing limitations on obtaining system performance in the real environment. Generally, a combination of ground and flight tests is necessary to quantify the propulsion system performance over the entire envelop of aircraft operation. To alleviate some of the dependence on flight-testing to obtain engine performance during maneuvers or transients that are not currently done during ground testing, a planned enhancement to ground-test facilities was investigated and reported in this paper that will allow certain categories of flight maneuvers to be conducted. Ground-test facility performance is simulated via a numerical model that duplicates the current facility capabilities and with proper modifications represents planned improvements that allow certain aircraft maneuvers. The vision presented in this paper includes using an aircraft simulator that uses pilot inputs to maneuver the aircraft engine. The aircraft simulator then drives the facility to provide the correct engine environmental conditions represented by the flight maneuver.
Parametric Performance of Combined-Cogeneration Power Plants With Various Power and Efficiency Enhancements
Authors: Korakianitis T. , Grantstrom J. , Wassingbo P. , Massardo Aristide F.
Published: February 2005

The design-point performance characteristics of a wide variety of combined-cogeneration power plants, with different amounts of supplementary firing (or no supplementary firing), different amounts of steam injection (or no steam injection), different amounts of exhaust gas condensation, etc., without limiting these parameters to present-day limits are investigated. A representative power plant with appropriate components for these plant enhancements is developed. A computer program is used to evaluate the performance of various power plants using standard inputs for component efficiencies, and the design-point performance of these plants is computed. The results are presented as thermal efficiency, specific power, effectiveness, and specific rate of energy in district heating. The performance of the simple-cycle gas turbine dominates the overall plant performance; the plant efficiency and power are mainly determined by turbine inlet temperature and compressor pressure ratio; increasing amounts of steam injection in the gas turbine increases the efficiency and power; increasing amounts of supplementary firing decreases the efficiency but increases the power; with sufficient amounts of supplementary firing and steam injection the exhaust-gas condensate is sufficient to make up for water lost in steam injection; and the steam-turbine power is a fraction (0.1 to 0.5) of the gas-turbine power output. Regions of “optimum” parameters for the power plant based on design-point power, hot-water demand, and efficiency are shown. A method for fuel-cost allocation between electricity and hot water is recommended.
Suppression of Unstable Flow at Small Flow Rates in a Centrifugal Blower by Controlling Tip Leakage Flow and Reverse Flow
Authors: Ishida Mashiro , Surana Taufan , Ueki Hironobu , Sakaguchi Daisaku
Published: February 2005

The effects of the inlet recirculation arrangement on inducer stall and the diffuser width on diffuser stall in a high-specific-speed-type centrifugal impeller with inducer were analyzed by numerical simulation and also verified experimentally. It was found that the incipient unstable flow occurs due to a rolling-up vortex flow, resulting from an interaction between the tip leakage flow and the reverse flow accumulated at the pressure side immediately downstream of the inducer tip throat, in which a strong streamwise component of vorticity is included. By forming the inlet recirculation flow, the tip leakage vortex is effectively sucked into the suction ring groove, and the flow incidence is decreased simultaneously. The unstable flow range of the test blower was reduced significantly by about 45% without deteriorating the impeller characteristics by implementing optimally both the ring groove arrangement and the narrowed diffuser width.
Performance Degradation due to Blade Surface Roughness in a Single-Stage Axial Turbine
Authors: Yun Yong Il , Park Il Young , Song Seung Jin
Published: February 2005

Turbine blades experience significant surface degradation with service. Previous studies indicate that an order-of-magnitude or greater increase in roughness height is typical, and these elevated levels of surface roughness significantly influence turbine efficiency and heat transfer. This paper presents measurement and a mean-line analysis of turbine efficiency reduction due to blade surface roughness. Performance tests have been conducted in a low-speed, single-stage, axial flow turbine with roughened blades. Sheets of sandpaper with equivalent sandgrain roughnesses of 106 and 400 μm have been used to roughen the blades. The roughness heights correspond to foreign deposits on real turbine blades measured by Bons et al. [1]. In the transitionally rough regime (106 μm), normalized efficiency decreases by approximately 4% with either roughened stator or roughened rotor and by 8% with roughness on both the stator and rotor blades. In the fully rough regime (400 μm), normalized efficiency decreases by 2% with roughness on the pressure side and by 6% with roughness on the suction side. Also, the normalized efficiency decreases by 11% with roughness only on stator vanes, 8% with roughness only on rotor blades, and 19% with roughness on both the stator and rotor blades.
A New Method to Calculate the Coolant Requirements of a High-Temperature Gas Turbine Blade
Authors: Torbidoni Leonardo , Horlock J. H.
Published: February 2005

Earlier papers by the first author have described a computational method of estimating the cooling flow requirements of blade rows in a high-temperature gas turbine, for convective cooling alone and for convective plus film cooling. This method of analysis and computation, when applied to the whole blade chord was compared to a well-known semi-empirical method. In the current paper, a more sophisticated method is developed from the earlier work and is used to calculate the cooling flow required for a nozzle guide vane (the first blade row) of a high-temperature gas turbine, with given inlet gas temperature and coolant inlet temperature. Now the heat flux through an elementary cross-sectional area of the blade, at given spanwise (y) and chordwise (s) locations, is considered, with a guessed value of the elementary coolant flow [as a fraction dΨs of the external gas flow]. At the given s, integration along the blade length gives the blade metal temperatures at the outer and inner walls, Tbgy and Tbcly. If the value of Tbg at the blade tip y=H is assumed to be limited by material considerations to Tbg,max then the elementary coolant flow rate may be obtained by iteration. Summation along the chord then gives the total coolant flow, for the whole blade. Results using the method are then compared to a simpler calculation applied to the whole blade, which assumes chordwise constant temperatures and constant selected values of cooling efficiency and film-cooling effectiveness.
Propagation and Decay of Shock Waves in Turbofan Engine Inlets
Authors: Prasad Dilip , Feng Jinzhang
Published: February 2005

Numerical experiments are carried out to investigate the tone noise radiated from a turbofan engine inlet under conditions at which the relative flow past the rotor tip is supersonic. Under these conditions, the inlet tone noise is generated by the upstream-propagating rotor-locked shock wave field. The spatial evolution of this shock system is studied numerically for flows through two basic hard-walled configurations: a slender nacelle with large throat area and a thick nacelle with reduced throat area. With the flight Mach number set to 0.25, the spatial evolution of the acoustic power through the two inlets reveals that the reduced throat area inlet provides superior attenuation. This is attributed to the greater mean flow acceleration through its throat and is qualitatively in accord with one-dimensional theory, which shows that shock dissipation is enhanced at high Mach numbers. The insertion of a uniform extension upstream of the fan is shown to yield greater attenuation for the inlet with large throat area, while the acoustic performance of the reduced throat area inlet is degraded. This occurs because the interaction of the nacelle and spinner potential fields is weakened, resulting in a lower throat Mach number. The effect of forward flight on the acoustic power radiated from the two inlets is also investigated by examining a simulated static condition. It is shown that the slender nacelle radiates significantly less power at the static condition than in flight, whereas the power levels at the two conditions are comparable for the thick nacelle. The reason for this behavior is revealed to be a drastic overspeed near the leading edge of the slender nacelle, which occurs to a lesser degree in the case of the thick inlet. This has implications for ground acoustic testing of aircraft engines, which are discussed.
On the Use of Five-Hole Probes in the Testing of Industrial Centrifugal Compressors
Authors: Gilarranz Jose´ L. , Ranz Andrew J. , Kopko Jason A. , Sorokes James M.
Published: February 2005

This paper addresses the use of 5-hole probes in the testing of industrial centrifugal compressors. The 5-hole probes utilized for this work are of the conical-tip type and were used in a non-nulling configuration (i.e., the probes do not need to be rotated or moved in any way during the tests). These 5-hole probes proved to be fairly robust, making them practical for a nonlaboratory setting such as an industrial multistage compressor test stand. A discussion of 5-hole probes and how they function is provided, including an overview of the mathematical formulations and calibrations required to translate the pressure data gathered from the 5 holes into static and total pressures, velocities and flow angles. A method to transform these variables from a probe-based coordinate system to a machine-based coordinate system is also presented and schematics of this process are provided to aid the reader’s understanding. The testing performed on a prototype multistage centrifugal compressor using 5-hole probes is also discussed, showing that the probes provided valuable insight into the flowfield exiting the impellers and at the return bend. The hub-to-shroud velocity profile exiting an impeller was found to be more skewed than expected and was contributing to poor performance in the downstream stationary components. The measured flowfield from one of the tests is also compared against 3-D CFD results and comments are offered regarding the agreement between the analytical and measured results. Advantages and disadvantages of 5-hole probes as compared to more conventional instrumentation are presented. Finally, conclusions are drawn regarding the value of 5-hole probe data in the development and/or troubleshooting of high performance turbomachinery and in the validation/calibration of design and analysis tools.
Investigation of a Novel Secondary Flow Feature in a Turbine Cascade With End Wall Profiling
Authors: Ingram Grant , Gregory-Smith David , Harvey Neil
Published: February 2005

A novel secondary flow feature, previously unreported for turbine blading as far as the authors are aware, has been discovered. It has been found that it is possible to separate part of the inlet boundary layer on the blade row end wall as it is being over-turned and rolled up into the passage vortex. This flow feature has been discovered during a continuing investigation into the aerodynamic effects of non-axisymmetric end wall profiling. Previous work, using the low speed linear cascade at Durham University, has shown the potential of end wall profiling for reducing secondary losses. The latest study, the results of which are described here, was undertaken to determine the limits of what end wall profiling can achieve. The flow has been investigated in detail with pressure probe traversing and surface flow visualization. This has found that the inlet boundary locally separates, on the early suction side of the passage, generating significant extra loss which feeds directly into the core of the passage vortex. The presence of this new feature gives rise to the unexpected result that the secondary flow, as determined by the exit flow angle deviations and levels of secondary kinetic energy, can be reduced while at the same time the loss is increased. CFD was found to calculate the secondary flows moderately well compared with measurements. However, CFD did not predict this new feature, nor the increase in loss it caused. It is concluded that the application of non-axisymmetric end wall profiling, although it has been shown to be highly beneficial, can give rise to adverse features that current CFD tools are unable to predict. Improvements to CFD capability are required in order to be able to avoid such features, and obtain the full potential of end wall profiling.
The Pulsating Flow Field in a Mixed Flow Turbocharger Turbine: An Experimental and Computational Study
Authors: Palfreyman D. , Martinez-Botas R. F.
Published: February 2005

The turbine stage of an automotive pulse system turbocharger is subjected to an unsteady pulsating flow field due to the rapid opening and closing of the reciprocating engine exhaust valves. This leads to a complex and highly disturbed flow field within the delivery volute and turbine passages, which results in an unusual “hysteresis” type performance characteristic. The aim of this paper is to investigate the flow field within the turbine stage under these representative conditions, using a computational method validated against experimental data. This paper is separated into two sections. The first deals with the validation of the numerical code and modeling approach. A mesh dependency study is undertaken with cell discretization ranging 200,000, 850,000, and 1,750,000 cells, where the accuracy is assessed through comparison with experimental performance and flow field measurements. The second part presents an investigation of the flow field under pulse conditions. Time accurate spectra of turbine performance and flow properties at various locations in the turbine stage are presented, as well as contour plots of velocity within a turbine passage at two critical positions during the pulse period.
Experimental Study of the Flow and Thermal Development of a Row of Cooling Jets Impinging on a Rotating Concave Surface
Authors: Iacovides Hector , Kounadis Diamantis , Launder Brian E. , Li Jiankang , Xu Zeyuan
Published: February 2005

The paper reports an experimental study of impingement cooling in a rotating passage of semi-cylindrical cross section. Cooling fluid is injected from a row of five jet holes along the centerline of the flat surface of the passage and strikes the concave surface. The cooling passage rotates orthogonally about an axis parallel to that of the jets. Tests have been carried out, using water, both within the passage and as the jet fluid, at a fixed Reynolds number of 15,000, for clockwise and counter-clockwise rotation. Local Nusselt number measurements, using the liquid-crystal technique, show that under stationary conditions a high Nusselt number region develops around each impingement point, with secondary peaks half-way between impingement points. Rotation reduces heat transfer, leads to the disappearance of all secondary peaks and also, surprisingly, of some of the primary peaks. Flow visualization tests suggest that these changes in thermal behavior are caused because rotation increases the spreading rate of the jets. LDA and PIV measurements are also presented. They show that under stationary conditions the five jets exhibit a similar behavior, with their cores remaining intact up to the point of impingement at the top dead center. The LDA and PIV studies help explain the rather surprising thermal behavior under rotating conditions.
Influence of Stator Clocking on the Unsteady Three-Dimensional Flow in a Two-Stage Turbine
Authors: Bohn Dieter , Ren Jing , Sell Michael
Published: February 2005

To give insight into the influence of the clocking and the stator–rotor interaction, the unsteady three-dimensional (3D) flow through a two-stage turbine is simulated numerically, using a time marching Navier–Stokes computer code with a sliding mesh approach. A stator clocking is applied to the second stator vane over several circumferential positions. The numerical results are compared with the experimental one to check the availability of the code. Clocking effects on the turbine performance, wake trajectories, and outlet flow field are focused. A relative efficiency variation of about 0.52% is concluded among clocking positions. A link between the turbine efficiency and the wake trajectories on the midspan is shown based on the presented clocking analysis in the 3D unsteady flow field. The detailed illustration of the outlet flow field shows that the influence of the clocking at the outlet is focused on the temperature distribution.
Method for Analysis of Nonlinear Multiharmonic Vibrations of Mistuned Bladed Disks With Scatter of Contact Interface Characteristics
Authors: Petrov E. P. , Ewins D. J.
Published: February 2005

An efficient method for analysis of nonlinear vibrations of mistuned bladed disk assemblies has been developed. This development has facilitated the use of large-scale finite element models for realistic bladed disks, used hitherto in analysis of linear vibration, to be extended for the analysis of nonlinear multiharmonic vibration. The new method is based on a technique for the exact condensation of nonlinear finite element models of mistuned bladed disks. The model condensation allows the size of the nonlinear equations to be reduced to the number of degrees of freedom where nonlinear interaction forces are applied. The analysis of nonlinear forced response for simplified and realistic models of mistuned bladed disks has been performed. For a practical high-pressure bladed turbine disk, several types of nonlinear forced response have been considered, including mistuning by (i) scatter of underplatform dampers, (ii) shroud gap scatter, and (iii) blade frequency scatter in the presence of nonlinear shroud interactions.
An Acylation Cycle Regulates Localization and Activity of Palmitoylated Ras Isoforms
Authors: Rocks Oliver , Peyker Anna , Kahms Martin , Verveer Peter J. , Koerner Carolin , Lumbierres Maria , Kuhlmann Jürgen , Waldmann Herbert , Wittinghofer Alfred , Bastiaens Philippe I. H.
Published: February 2005

We show that the specific subcellular distribution of H- and Nras guanosine triphosphate–binding proteins is generated by a constitutive de/reacylation cycle that operates on palmitoylated proteins, driving their rapid exchange between the plasma membrane (PM) and the Golgi apparatus. Depalmitoylation redistributes farnesylated Ras in all membranes, followed by repalmitoylation and trapping of Ras at the Golgi, from where it is redirected to the PM via the secretory pathway. This continuous cycle prevents Ras from nonspecific residence on endomembranes, thereby maintaining the specific intracellular compartmentalization. The de/reacylation cycle also initiates Ras activation at the Golgi by transport of PM-localized Ras guanosine triphosphate. Different de/repalmitoylation kinetics account for isoform-specific activation responses to growth factors.
A Transmembrane Intracellular Estrogen Receptor Mediates Rapid Cell Signaling
Authors: Revankar Chetana M. , Cimino Daniel F. , Sklar Larry A. , Arterburn Jeffrey B. , Prossnitz Eric R.
Published: February 2005

The steroid hormone estrogen regulates many functionally unrelated processes in numerous tissues. Although it is traditionally thought to control transcriptional activation through the classical nuclear estrogen receptors, it also initiates many rapid nongenomic signaling events. We found that of all G protein–coupled receptors characterized to date, GPR30 is uniquely localized to the endoplasmic reticulum, where it specifically binds estrogen and fluorescent estrogen derivatives. Activating GPR30 by estrogen resulted in intracellular calcium mobilization and synthesis of phosphatidylinositol 3,4,5-trisphosphate in the nucleus. Thus, GPR30 represents an intracellular transmembrane estrogen receptor that may contribute to normal estrogen physiology as well as pathophysiology.
Microwave Manipulation of an Atomic Electron in a Classical Orbit
Authors: Maeda H. , Norum D. V. L. , Gallagher T. F.
Published: February 2005

Although an atom is a manifestly quantum mechanical system, the electron in an atom can be made to move in a classical orbit almost indefinitely if it is exposed to a weak microwave field oscillating at its orbital frequency. The field effectively tethers the electron, phase-locking its motion to the oscillating microwave field. By exploiting this phase-locking, we have sped up or slowed down the orbital motion of the electron in excited lithium atoms by increasing or decreasing the microwave frequency between 13 and 19 gigahertz; the binding energy and orbital size change concurrently.
Discerning an Effective Balance between Equine Infectious Anemia Virus Attenuation and Vaccine Efficacy
Authors: Craigo Jodi K. , Li Feng , Steckbeck Jonathan D. , Durkin Shannon , Howe Laryssa , Cook Sheila J. , Issel Charles , Montelaro Ronald C.
Published: February 2005

Among the diverse experimental vaccines evaluated in various animal lentivirus models, live attenuated vaccines have proven to be the most effective, thus providing an important model for examining critical immune correlates of protective vaccine immunity. We previously reported that an experimental live attenuated vaccine for equine infectious anemia virus (EIAV), based on mutation of the viral
S2
accessory gene, elicited protection from detectable infection by virulent virus challenge (F. Li et al., J. Virol. 77:7244-7253, 2003). To better understand the critical components of EIAV vaccine efficacy, we examine here the relationship between the extent of virus attenuation, the maturation of host immune responses, and vaccine efficacy in a comparative study of three related attenuated EIAV proviral vaccine strains: the previously described EIAV
UK
ΔS2 derived from a virulent proviral clone, EIAV
UK
ΔS2/DU containing a second gene mutation in the virulent proviral clone, and EIAV
PR
ΔS2 derived from a reference avirulent proviral clone. Inoculations of parallel groups of eight horses resulted in relatively low levels of viral replication (average of 10
2
to 10
3
RNA copies/ml) and a similar maturation of EIAV envelope-specific antibody responses as determined in quantitative and qualitative serological assays. However, experimental challenge of the experimentally immunized horses by our standard virulent EIAV
PV
strain by using a low-dose multiple exposure protocol (three inoculations with 10 median horse infective doses, administered intravenously) revealed a marked difference in the protective efficacy of the various attenuated proviral vaccine strains that was evidently associated with the extent of vaccine virus attenuation, time of viral challenge, and the apparent maturation of virus-specific immunity.
Regulating Intracellular Antiviral Defense and Permissiveness to Hepatitis C Virus RNA Replication through a Cellular RNA Helicase, RIG-I
Authors: Sumpter Rhea , Loo Yueh-Ming , Foy Eileen , Li Kui , Yoneyama Mitsutoshi , Fujita Takashi , Lemon Stanley M. , Gale Michael
Published: February 2005

Virus-responsive signaling pathways that induce alpha/beta interferon production and engage intracellular immune defenses influence the outcome of many viral infections. The processes that trigger these defenses and their effect upon host permissiveness for specific viral pathogens are not well understood. We show that structured hepatitis C virus (HCV) genomic RNA activates interferon regulatory factor 3 (IRF3), thereby inducing interferon in cultured cells. This response is absent in cells selected for permissiveness for HCV RNA replication. Studies including genetic complementation revealed that permissiveness is due to mutational inactivation of RIG-I, an interferon-inducible cellular DExD/H box RNA helicase. Its helicase domain binds HCV RNA and transduces the activation signal for IRF3 by its caspase recruiting domain homolog. RIG-I is thus a pathogen receptor that regulates cellular permissiveness to HCV replication and, as an interferon-responsive gene, may play a key role in interferon-based therapies for the treatment of HCV infection.
Establishment of a Subgenomic Replicon for Bovine Viral Diarrhea Virus in Huh-7 Cells and Modulation of Interferon-Regulated Factor 3-Mediated Antiviral Response
Authors: Horscroft Nigel , Bellows Dan , Ansari Israrul , Lai Vicky C. H. , Dempsey Shannon , Liang Delin , Donis Ruben , Zhong Weidong , Hong Zhi
Published: February 2005

We describe the development of a selectable, bi-cistronic subgenomic replicon for bovine viral diarrhea virus (BVDV) in Huh-7 cells, similar to that established for hepatitis C virus (HCV). The selection marker and reporter (
Luc-Ubi-Neo
) in the BVDV replicon was fused with the amino-terminal protease N
pro
, and expression of the nonstructural proteins (NS3 to NS5B) was driven by an encephalomyocarditis virus internal ribosome entry site. This BVDV replicon allows us to compare RNA replication of these two related viruses in a similar cellular background and to identify antiviral molecules specific for HCV RNA replication. The BVDV replicon showed similar sensitivity as the HCV replicon to interferons (alpha, beta, and gamma) and 2′-β-C-methyl ribonucleoside inhibitors. Known nonnucleoside inhibitor molecules specific for either HCV or BVDV can be easily distinguished by using the parallel replicon systems. The HCV replicon has been shown to block, via the NS3/4A serine protease, Sendai virus-induced activation of interferon regulatory factor 3 (IRF-3), a key antiviral signaling molecule. Similar suppression of IRF-3-mediated responses was also observed with the Huh-7-BVDV replicon but was independent of NS3/4A protease activity. Instead, the amino-terminal cysteine protease N
pro
of BVDV appears to be, at least partly, responsible for suppressing IRF-3 activation induced by Sendai virus infection. This result suggests that different viruses, including those closely related, may have developed unique mechanisms for evading host antiviral responses. The parallel BVDV and HCV replicon systems provide robust counterscreens to distinguish viral specificity of small-molecule inhibitors of viral replication and to study the interactions of the viral replication machinery with the host cell innate immune system.
Characterization of a Novel Influenza A Virus Hemagglutinin Subtype (H16) Obtained from Black-Headed Gulls
Authors: Fouchier Ron A. M. , Munster Vincent , Wallensten Anders , Bestebroer Theo M. , Herfst Sander , Smith Derek , Rimmelzwaan Guus F. , Olsen Björn , Osterhaus Albert D. M. E.
Published: February 2005

In wild aquatic birds and poultry around the world, influenza A viruses carrying 15 antigenic subtypes of hemagglutinin (HA) and 9 antigenic subtypes of neuraminidase (NA) have been described. Here we describe a previously unidentified antigenic subtype of HA (H16), detected in viruses circulating in black-headed gulls in Sweden. In agreement with established criteria for the definition of antigenic subtypes, hemagglutination inhibition assays and immunodiffusion assays failed to detect specific reactivity between H16 and the previously described subtypes H1 to H15. Genetically, H16 HA was found to be distantly related to H13 HA, a subtype also detected exclusively in shorebirds, and the amino acid composition of the putative receptor-binding site of H13 and H16 HAs was found to be distinct from that in HA subtypes circulating in ducks and geese. The H16 viruses contained NA genes that were similar to those of other Eurasian shorebirds but genetically distinct from N3 genes detected in other birds and geographical locations. The European gull viruses were further distinguishable from other influenza A viruses based on their PB2, NP, and NS genes. Gaining information on the full spectrum of avian influenza A viruses and creating reagents for their detection and identification will remain an important task for influenza surveillance, outbreak control, and animal and public health. We propose that sequence analyses of HA and NA genes of influenza A viruses be used for the rapid identification of existing and novel HA and NA subtypes.