bluuebunny/crossref_metadata_2025 huggingface dataset:
Electric‐Field‐Induced Crack Initiation From a Notch in a Ferroelectric Ceramic
Authors: Westram Ilona , Lupascu Doru , Rödel Jürgen , Laskewitz Bernd , Kamlah Marc
Published: July 2007

Crack initiation of ferroelectrics under a cyclic electric field was studied using DCB specimens, which contained through‐thickness notches of different lengths. An electric field larger than the coercive field strength of the material was applied and resulted in pop‐in of a crack in the direction perpendicular to the field. The length of the pop‐in varied with the length of the notch. Finite Element modeling was used to quantify the stresses occurring in the specimen under the application of the electric field. The model took into account the fully coupled ferroelectric and ferroelastic hysteresis behavior. Stress intensity factors were derived from the resulting stress distribution using the weight function method. The results were found to agree well with the experimental data.
Effect of Aluminum Phosphate Additions on the Crystallization and Bioactivity of Fluorrichterite Glass–Ceramics for Biomedical Applications
Authors: Holloway Julie A. , Denry Isabelle
Published: July 2007

This study evaluated the effect of aluminum phosphate (AlPO4) additions on the crystallization behavior and bioactivity of potassium fluorrichterite glasses and glass–ceramics. Four glass compositions with increasing amounts of AlPO4 were melted. Mica and fluorrichterite were present in all glass–ceramics after crystallization. The microstructure consisted of platelet‐shaped mica and prismatic fluorrichterite crystals. After incubation in simulated body fluid, a layer consisting of spherical‐nanosized particles was present on the surface of the glasses. X‐ray diffraction revealed the presence of hydroxyapatite after incubation of the glass and glass–ceramic powders. The addition of AlPO4 promoted mica nucleation and bioactivity in K‐fluorrichterite glass–ceramics.
Productivity growth and convergence in crop, ruminant, and nonruminant production: measurement and forecasts
Authors: Ludena Carlos E. , Hertel Thomas W. , Preckel Paul V. , Foster Kenneth , Nin Alejandro
Published: July 2007

Projections of future productivity growth rates in agriculture are an essential input for a great variety of tasks, ranging from development of an outlook for global commodity markets to the analysis of interactions between land use, deforestation, and ecological diversity. Yet solid projections for these variables have proven elusive—particularly on a global basis. This is due, in no small part, to the difficulty of measuring historical total factor productivity growth. Consequently, most productivity projections are based on partial factor productivity measures that can be quite misleading. The purpose of this work is to provide worldwide forecasts of agricultural productivity growth till the year 2040 based on the latest time series evidence on total factor productivity growth for crops, ruminants, and nonruminant livestock. The results suggest that most regions in the sample are likely to experience larger productivity gains in livestock than in crops. Within livestock, the nonruminant sector is expected to continue to be more dynamic than the ruminant sector. Given the rapid rates of productivity growth observed recently, nonruminant and crop productivity in developing countries may be converging to the productivity levels of developed countries. For ruminants, the results show that productivity levels in developing countries are likely to be diverging from those in developed countries.
Can the U.S. ethanol industry compete in the alternative fuels market?
Authors: Zhang Zibin , Vedenov Dmitry , Wetzstein Michael
Published: July 2007

The U.S. ethanol fuel industry has experienced preferential treatment from federal and state governments ever since the Energy Tax Act of 1978 exempted 10% ethanol/gasoline blend (gasohol) from the federal excise tax. Combined with a 54c/ /gal ethanol import tariff, this exemption was designed to provide incentives for the establishment and development of a U.S. ethanol industry. Despite these tax exemptions, until recently, the U.S. ethanol fuel industry was unable to expand from a limited regional market. Ethanol was dominated in the market by MTBE (methyl‐tertiary‐butyl ether). Only after MTBE was found to contaminate groundwater and consequently banned in many states did the demand for ethanol expand nationally. Limit pricing on the part of MTBE refiners is one hypothesis that may explain this lack of ethanol entry into the fuel‐additives market. As a test of this hypothesis, a structural vector autoregression (SVAR) model of the ethanol fuel market is developed. The results support the hypothesis of limit‐pricing behavior on the part of MTBE refiners, and suggest the U.S. corn‐based ethanol industry is vulnerable to limit‐price competition, which could recur. The dependence of the corn‐based ethanol price on supply determinants limits U.S. ethanol refiners' ability to price compete with sugar‐cane‐based ethanol refiners. Without federal support, U.S. ethanol refiners may find it difficult to compete with cheaper sugar‐cane‐refined ethanol, chiefly from Brazil.
Duration of Allergic Susceptibility in Maternal Transmission of Asthma Risk
Authors: Fedulov Alexey V. , Leme Adriana S. , Kobzik Lester
Published: July 2007

Problem

Asthma has its origins in early‐life. Maternal, not paternal asthma is an important risk factor, but the mechanisms and the duration of the maternal effect are unknown.

Method of Study

Offspring of asthmatic and normal mice were sensitized with ovalbumin (OVA) at 1, 3, 6 and 10 weeks of age, challenged with aerosolized OVA 2 weeks later and tested for airway hyperresponsiveness (AHR) and allergic airway inflammation (AI).

Results

Offspring of asthmatic, but not normal, mothers showed AHR and AI after OVA sensitization at week 1. Similarly increased susceptibility to OVA was observed when sensitized at 3 or 6 weeks, although the magnitude diminished. Offspring sensitized at 10 and challenged at 12 weeks showed some AI but no AHR.

Conclusion

In offspring from asthmatic mothers increased allergic susceptibility persisted through the young adulthood, albeit with gradual decline, which suggests a long‐lived but reversible skewing of the developing immune system.
Targeting Mast Cells in Endometriosis with Janus Kinase 3 Inhibitor, JANEX‐1
Authors: D’Cruz Osmond J. , Uckun Fatih M.
Published: July 2007

Endometriosis (EMS) is a chronic inflammatory disease of multifactorial etiology characterized by implantation and growth of endometrial glands and stroma outside the uterine cavity. EMS is a significant public health issue as it affects 15–20% of women in their reproductive age. Clinical symptoms may include pelvic pain, dysmenorrhea, dyspareunia, pelvic/abdominal masses, and infertility. Symptomatic treatments such as surgical resection and/or hormonal suppression of ovarian function and analgesics are not as effective as desired. Consequently, there is an enormous unmet need to develop effective medical therapy capable of preventing the occurrence and recurrence of EMS without undesirable side‐effects. EMS‐associated intra‐abdominal bleeding episodes, local inflammation, adhesions, and i.p. immunologic dysfunction leads to pelvic nociception and pelvic pain. Increasing evidence supports the involvement of allergic‐type inflammation in EMS. Invasion of mast cells, degranulation, and proliferation of interstitial component are observed in endometriotic lesions. Presence of activated and degranulating mast cells within the nerve structures can contribute to the development of pain and hyperalgesia by direct effects on primary nociceptive neurons. Therefore, treatments targeting endometrial mast cells may prove effective in preventing or alleviating EMS‐associated symptoms. The Janus kinase 3 (JAK3) is abundantly expressed in mast cells and is required for the full expression of high‐affinity IgE receptor‐mediated mast cell inflammatory sequelae. JANEX‐1/WHI‐P131 is a rationally designed novel JAK3 inhibitor with potent anti‐inflammatory activity in several cellular andin vivoanimal models of inflammation, including mouse models of peritonitis, colitis, cellulitis, sunburn, and airway inflammation with favorable toxicity and pharmacokinetic profile. We hypothesize that JAK3 inhibitors, especially JANEX‐1, may prove useful to prevent or alleviate the symptoms of EMS.
Formation Pathways and Opioid Activity Data for 3‐Hydroxypyridinium Compounds Derived from Glucuronic Acid and Opioid Peptides by Maillard Processes
Authors: Horvat Štefica , Roščić Maja , Lemieux Carole , Nguyen Thi M.‐D. , Schiller Peter W.
Published: July 2007

The kinetics of formation and identity of the reaction products of the glucuronic acid with three representative opioid peptides were investigatedin vitro. Peptides were conjugated with glucuronic acid either in solution or under dry‐heating conditions. From the incubations performed in solutionN‐(1‐deoxy‐d‐fructofuranos‐1‐yluronic acid)‐peptide derivatives (Amadori compounds) were isolated, whereas from the dry‐heated reactions products containing the 3‐hydroxypyridinium moiety at the N‐terminal of the peptide chain were obtained. Experiments performed under mild dry‐heating conditions (40 °C) in model systems based on Leu‐enkephalin and glucuronic acid, and in environment of either 40% or 75% relative humidity, revealed that the higher level of humidity promoted a process that enhanced 3‐hydroxypyridinium compound generation. The mechanism of 3‐hydroxypyridinium formation is discussed. In comparison with their respective parent peptides, theN‐(1‐deoxy‐d‐fructofuranosyl‐uronic acid) derivatives of the opioid peptides showed three‐ to 11‐fold lowerμ‐ andδ‐receptor‐binding affinities and agonist potencies in the functional assays, likely as a consequence of the steric bulk introduced at the N‐terminal amino group. The further decrease in opioid activity observed with the 3‐hydroxypyridinium‐containing peptides may be due to the lower pKaof the 3‐hydroxypyridinium moiety and to delocalization of the positive charge in the pyridinium ring system.
Processing Tangerine Tomatoes: Effects on Lycopene‐Isomer Concentrations and Profile
Authors: Ishida B.K. , Roberts J.S. , Chapman M.H. , Burri B.J.
Published: July 2007

ABSTRACT:  Because lycopene is a powerful biological antioxidant, its delivery to humans is of major concern. cis‐Lycopene isomers are more bioavailable than the all‐trans isomers and thus more efficiently absorbed. Tangerine tomatoes, whose lycopene isomeric content is almost all tetra‐cis, provide a useful food source for comparing cis‐ and trans‐isomer absorption. Tangerine tomatoes were processed into sauce in the Univ. of California, Davis Pilot Plant for subsequent use in a human feeding study described in another publication. Samples were taken at several stages during processing and carotenoids extracted and analyzed for carotenoid‐isomer profiles and concentrations. Analyses showed that total lycopene concentration decreased considerably during the 1st step of processing, which included heating and juicing operations. Processing resulted in a large decrease in tetra‐cis lycopene concentration accompanied by increases in trans‐ and other cis‐lycopene isomers.
Oxidation of Corn Oil During Frying of Soy–Flour‐Added Flour Dough
Authors: Yoon Y. , Choe E.
Published: July 2007

ABSTRACT:  Oxidation of corn oil during frying of soy–flour‐added dough was studied. Flour dough containing soy flour at 0%, 10%, 20%, and 30% was fried in corn oil at 180 °C for 2.5 min, and a total of 60 fryings were performed every 30 min. The oxidation of oil was determined by contents of free fatty acids (FFA), conjugated dienoic acids (CDA), polar compounds, and p‐anisidine values (PAV). Tocopherols and phospholipids (PLs) in the oil were determined by HPLC. Tocopherols were present in corn oil at 1000 ppm before frying and increased after the first frying of dough containing soy flour due to tocopherol transfer from soy–flour‐added dough to the oil during frying. However, as the oil repeated frying, tocopherol contents decreased and its degradation rate was higher in the oil that fried soy–flour‐added dough than in the oil that fried the dough without soy flour. PL was not detected in corn oil before and after frying. As the oil repeated frying, FFA, CDA, and polar compounds contents, and PAV of frying oil increased due to the oil oxidation. The values were higher in the oil which fried soy–flour‐added dough than in the oil fried the dough without soy flour, indicating the acceleration of oil oxidation by soy flour added to dough. Increase in the oil oxidation by soy flour added to the dough was highly correlated with fast decomposition of tocopherol in the oil.
Sensory Properties of Meal Replacement Bars and Beverages Made from Whey and Soy Proteins
Authors: Childs J.L. , Yates M.D. , Drake M.A.
Published: July 2007

ABSTRACT: Whey and soy proteins have a variety of applications. Previous work has documented flavors of rehydrated whey and soy proteins. It is necessary to understand what flavors whey and soy proteins contribute to product applications to optimize protein performance in desired applications. This research was conducted to characterize sensory properties of meal replacement products containing whey and soy proteins. Flavor and texture lexicons were developed for meal replacement bars and beverages. Commercial peanut butter‐flavored meal replacement bars and vanilla meal replacement shakes were evaluated by an experienced, trained descriptive panel (n= 9). Prototypes of bars and beverages were developed with 3 levels of whey and soy protein and subsequently evaluated. Consumer acceptance testing (n= 85) was conducted on the prototype bars and beverages. Protein type as well as product‐specific formulation contributed differences in flavor and texture of commercial bars and beverages (P< 0.05). Sensory properties of prototype bars and beverages fell within the spectrum of commercial products. Prototype bars made with whey protein were characterized by sweet aromatic and vanillin flavor notes while the texture was characterized by adhesiveness and cohesiveness. Prototype bars made with soy protein were characterized by nutty flavor while the texture was characterized by tooth‐pack and denseness. Whey protein contributed to sweet aromatic and vanillin flavors in prototype beverages while soy protein contributed cereal/grainy flavors. Consumer acceptance scores were higher for prototype bars and beverages containing whey protein or a mixture of whey/soy protein than for products made with soy protein alone (P< 0.05). These results will aid researchers and product developers in optimizing sensory quality in meal replacement products.
Potential of a Novel Polysaccharide Preparation (GLPP) from Anhui‐Grown Ganoderma lucidum in Tumor Treatment and Immunostimulation
Authors: Pang X. , Chen Z. , Gao X. , Liu W. , Slavin M. , Yao W. , Yu L.L.
Published: July 2007

ABSTRACT:  Growing evidence indicates the potential of developing novel polysaccharide‐based adjuvant for tumor therapy from edible mushrooms, including Ganoderma lucidum. In the present study, a novel polysaccharide preparation (GLPP) was isolated from the fruiting body of G. lucidum grown in Anhui, China, and characterized for its physicochemical properties. GLPP had an average molecular weight of 6600 and a specific optical rotation of +25.6°, contained 10.6% protein, and had a molar ratio of 0.9:15:1 for mannose, glucose, and galactose, respectively. GLPP was also investigated and compared with PSP (polysaccharopeptide preparation), a commercial antitumor and immunostimulating agent, for its antitumor and immunostimulation capacity, and potential in reducing the toxic effects induced by cyclophosphamide (Cy) treatment and Cobalt‐60 (60Co) radiation in mice. GLPP at levels of 100 and 300 mg/kg body weight (BW)/d significantly inhibited the growth of inoculated S180, Heps, and EAC tumor cells in mice. GLPP at a dose of 300 mg/kg BW/d showed stronger growth inhibition against all 3 tested tumor cells than PSP at 1 g/kg BW/d. GLPP also dose‐dependently increased phagocytic index, phagocytic coefficient, and 50% hemolysin value in the EAC tumor‐bearing mice, indicating its potential immunostimulating property. In addition, GLPP at 300 mg/kg BW/d was comparable to PSP at 1000 mg/kg BW/d in preventing the decrease of thymus index, spleen index, white blood cells, and bone marrow karyote numbers induced by Cy treatment and 60Co radiation. These data demonstrated the potential utilization of GLPP as an adjuvant to conventional treatments of cancers and its use for cancer prevention.
On Tests for a Normal Mean with Known Coefficient of Variation
Authors: Bhat Kavitha , Rao K. Aruna
Published: July 2007

Hinkley (1977) derived two tests for testing the mean of a normal distribution with known coefficient of variation (c.v.) for right alternatives. They are the locally most powerful (LMP) and the conditional tests based on the ancillary statistic for μ. In this paper, the likelihood ratio (LR) and Wald tests are derived for the one‐ and two‐sided alternatives, as well as the two‐sided version of the LMP test. The performances of these tests are compared with those of the classical t, sign and Wilcoxon signed rank tests. The latter three tests do not use the information on c.v. Normal approximation is used to approximate the null distribution of the test statistics except for the t test. Simulation results indicate that all the tests maintain the type‐I error rates, that is, the attained level is close to the nominal level of significance of the tests. The power functions of the tests are estimated through simulation. The power comparison indicates that for one‐sided alternatives the LMP test is the best test whereas for the two‐sided alternatives the LR or the Wald test is the best test. The t, sign and Wilcoxon signed rank tests have lower power than the LMP, LR and Wald tests at various alternative values of μ. The power difference is quite large in several simulation configurations. Further, it is observed that the t, sign and Wilcoxon signed rank tests have considerably lower power even for the alternatives which are far away from the null hypothesis when the c.v. is large. To study the sensitivity of the tests for the violation of the normality assumption, the type I error rates are estimated on the observations of lognormal, gamma and uniform distributions. The newly derived tests maintain the type I error rates for moderate values of c.v.
Japanese case of hepatitis B virus genotypes C/D hybrid
Authors: Yano Yoshihiko , Truong Bui X. , Seo Yasushi , Kato Hirotaka , Miki Akira , Tanaka Yasuhito , Mizokami Masashi , Kagawa Ayako , Miyazaki Hiroyuki , Kasuga Masato , Azuma Takeshi , Hayashi Yoshitake
Published: July 2007

Hepatitis B virus (HBV) is classified into eight genotypes based on complete genome sequence. Each genotype is related to geographic distribution and race. In Japan, most of the genotypes are B and C. In the present study, we report the first Japanese strain of HBV having a recombination between genotypes C and D. A 30‐year‐old woman was admitted to Kobe Medical Center because of liver dysfunction. She was diagnosed with spontaneous reactivation of chronic hepatitis B. She had no history of blood transfusion and her parents were negative for HBV. The phylogenetic analysis based on the complete genome sequences revealed that this strain was classified into genotype C, whereas the analysis based on Sgene sequence showed that this strain was genotype D. By using a SimPlot program, this strain was confirmed as a recombinant strain between genotypes C and D. Compared with previous recombinant strains in China, the breakpoint was the same and the difference was only 0.8% of the complete genome sequence. It was unclear whether or not this strain was transmitted from China, but the recombinant strains and intergenotypes of HBV have already existed in Japan.
Experimental and Computational Studies on Gasoline HCCI Combustion Control Using Injection Strategies
Authors: Wang Zhi , Wang Jian-Xin , Shuai Shi-Jin , Tian Guo-Hong , An Xin Liang
Published: July 2007

Homogeneous Charge Compression Ignition (HCCI) has challenges of ignition control. In this paper, HCCI ignition timing and combustion rate were controlled by two-stage direct injection (TSDI) strategies on a four-stroke gasoline HCCI engine. TSDI strategy was proposed to solve the two major problems of HCCI application-ignition control and load extension. Both simulation and experiments were carried out on a gasoline HCCI engine with negative valve overlap (NVO). An engine model with detailed chemical kinetics was established to study the gas exchange process and the direct injection strategy in the gasoline HCCI engine with TSDI and NVO. Simulation results were compared with experiments and good agreement was achieved. The simulated and experimental results provided a detailed insight into the processes governing ignition in the HCCI engine. Using TSDI, the fuel concentration, temperature as well as chemical species can be controlled. The effects of different injection parameters, such as split injection ratio and start-of-injection (SOI) timing, were studied. The experimental results indicate that, two-stage direct injection is a practical technology to control the ignition timing and combustion rate effectively in four-stroke gasoline HCCI engines. Both the high load and low load limits of HCCI operation were extended.
Enhanced Gas Turbine Performance Simulation Using CFD Modules in a 2D Representation of the Low-Pressure System for a High-Bypass Turbofan
Authors: Mund Friederike C. , Doulgeris Georgios , Pilidis Pericles
Published: July 2007

The improvement of performance simulation for gas turbines has been approached in very different ways. In particular for high-bypass turbofans, efforts have been made to investigate radial flow distributions. The aim of the presented study was to combine a conventional characteristics-based performance code using a 2D representation of the fan with 2D representations of the adjoining intake and bypass system. Computational fluid dynamics (CFD) was the chosen tool to generate modules for the intake, bypass duct, and bypass nozzle. This approach required geometry data. A design procedure to generate these components in an axisymmetric meridional fashion and the numerical requirements for the CFD modules were developed. Typical component performances were predicted and the combined use of CFD and the performance code showed that in terms of performance, the inclusion of intake and bypass losses and the radial inlet distribution was worth considering. In particular, however, the required numerical effort was significant.
Development, Testing, and Implementation of a Gas Turbine Starting Clutch With Manual Turning Feature for U.S. Navy Ships
Authors: Hendry Morgan L. , Hoffman Matthew G.
Published: July 2007

Most gas turbine generators rely on an automatic-engaging, free-wheel clutch to connect a starting motor to accelerate the gas turbine generator from zero to some intermediate speed to enable ignition and then provide torque assistance to a higher speed until the gas turbine is self-sustaining. The U.S. Navy has used various designs of starter motors and clutches for its gas turbine fleet. In addition, there has been a requirement to periodically borescope each gas turbine, which has necessitated removal of the starting system and clutch assembly in each instance. This paper examines the U.S. Navy experience with starting clutches and provides details of the development and testing of a synchronous-self-shifting clutch with an additional, stationary, manual turning feature to provide very slow and precise gas turbine rotor rotation for borescope purposes. This paper also gives details of the installation of the first two prototype clutches on the USS Ramage, DDG 61, operating experience for approximately four years, and possible future installations of this type of clutch in U.S. Navy gas turbine generator sets.
Experimental and Kinetic Modeling of Kerosene-Type Fuels at Gas Turbine Operating Conditions
Authors: Gokulakrishnan P. , Gaines G. , Currano J. , Klassen M. S. , Roby R. J.
Published: July 2007

Experimental and kinetic modeling of kerosene-type fuels is reported in the present work with special emphasis on the low-temperature oxidation phenomenon relevant to gas turbine premixing conditions. Experiments were performed in an atmospheric pressure, tubular flow reactor to measure ignition delay time of kerosene (fuel–oil No. 1) in order to study the premature autoignition of liquid fuels at gas turbine premixing conditions. The experimental results indicate that the ignition delay time decreases exponentially with the equivalence ratio at fuel-lean conditions. However, for very high equivalence ratios (>2), the ignition delay time approaches an asymptotic value. Equivalence ratio fluctuations in the premixer can create conditions conducive for autoignition of fuel in the premixer, as the gas turbines generally operate under lean conditions during premixed prevaporized combustion. Ignition delay time measurements of stoichiometric fuel–oil No. 1∕air mixture at 1 atm were comparable with that of kerosene type Jet-A fuel available in the literature. A detailed kerosene mechanism with approximately 1400 reactions of 550 species is developed using a surrogate mixture of n-decane, n-propylcyclohexane, n-propylbenzene, and decene to represent the major chemical constituents of kerosene, namely n-alkanes, cyclo-alkanes, aromatics, and olefins, respectively. As the major portion of kerosene-type fuels consists of alkanes, which are relatively more reactive at low temperatures, a detailed kinetic mechanism is developed for n-decane oxidation including low temperature reaction kinetics. With the objective of achieving a more comprehensive kinetic model for n-decane, the mechanism is validated against target data for a wide range of experimental conditions available in the literature. The data include shock tube ignition delay time measurements, jet-stirred reactor reactivity profiles, and plug-flow reactor species time–history profiles. The kerosene model predictions agree fairly well with the ignition delay time measurements obtained in the present work as well as the data available in the literature for Jet A. The kerosene model was able to reproduce the low-temperature preignition reactivity profile of JP-8 obtained in a flow reactor at 12 atm. Also, the kerosene mechanism predicts the species reactivity profiles of Jet A-1 obtained in a jet-stirred reactor fairly well.
Assessment of the Computing Time for the IAPWS-IF97 Equations
Authors: Miyagawa Kiyoshi
Published: July 2007

Computing times of equations based on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97) were tested. Modern computer systems are optimized for “simple” computational operations, which favors the simple structure of IAPWS-IF97. Provision of “backward equations,” which are approximation of inverse equations, is one of the features of IAPWS-IF97. The backward equations showed much shorter computing times than iterative routines, which had been used to calculate with several independent variables. IAPWS-IF97 is faster than the equations of IAPWS Formulation 1995 for the Thermodynamic properties of Ordinary Water Substance for General and Scientific Use (IAPWS-95) by factors 70 to 200 times.
Vibration Characteristics of a 75kW Turbo Machine With Air Foil Bearings
Authors: Kim Kyeong-Su , Lee In
Published: July 2007

Air foil bearings are very attractive bearing systems for turbomachinery because they have several advantages over conventional bearings in terms of oil-free environment, low power loss, long life, and no maintenance. However, most of the developed machines using air foil bearings are limited to small and high-speed rotors of 60,000–120,000 rpm, since the increase in power of turbomachinery requires lower rotor speed and greater loading in bearings, which makes it difficult to use air foil bearings for large machines. In this paper, a 75 kW turboblower using air foil bearings is introduced, and the vibration characteristics of the machine have been investigated experimentally under a wide range of operating conditions, including compressor surge in the performance test. The machine is designed to be fully air lubricated and air cooled, and its operating speed is 20,000–26,000 rpm with maximum pressure ratio of 1.8. The results show that the air foil bearings offer adequate damping to ensure dynamically stable operation in the whole range.
Water Injection Effects on Compressor Stage Operation
Authors: Roumeliotis I. , Mathioudakis K.
Published: July 2007

In the present paper, experimental work concerning the effect of water injection on a compressor stage is presented. The effect on compressor stage performance and stability is examined for water injection up to 2%. The behavior of the airflow in the blade rows is examined through aerodynamic measurements. The results indicate that although the water injection appears to not have any significant effect on the flow pattern and to stage pressure rise and stall margin, there is a measurable effect on compression efficiency, which seems to result mainly from losses of a mechanical nature and water acceleration. The efficiency degradation is proportional to the water ratio entering the engine.
Laser-Based Investigations of Thermoacoustic Instabilities in a Lean Premixed Gas Turbine Model Combustor
Authors: Weigand Peter , Meier Wolfgang , Duan Xuru , Aigner Manfred
Published: July 2007

Nonintrusive laser-based and optical measurements were performed in a gas turbine model combustor with a lean premixed swirl-stabilized CH4-air flame at atmospheric pressure. The main objective was to gain spatially and temporally resolved experimental data to enable the validation of numerical CFD results of oscillating flames. The investigated flame was operated at 25 kW and ϕ=0.70, and exhibited self-excited oscillations of more than 135 dB at ≈300Hz. The applied measurement techniques were three-dimensional (3D) laser doppler velocimetry (LDV) for velocity measurements, OH* chemiluminescence yielding information about the heat release and pointwise laser Raman scattering for the determination of joint probability density functions (PDFs) of the major species concentrations, temperature, and mixture fraction. Each of these techniques was applied with phase resolution with respect to the periodic fluctuation of the pressure in the combustion chamber that was measured with a microphone probe. The measurements finally revealed that the mixing of fuel and air in this technical premixing system was strongly affected by the pressure fluctuations leading to changes in equivalence ratio during an oscillation cycle that, in turn, induced the pressure fluctuations.
Engine Performance Improvement by Controlling the Low Pressure Compressor Working Line
Authors: Martis Dan , Rowe Arthur , Price Brian , Edwards Darryl , Perez Vincent , Pinquier Marie-Laure , Mhana Samer , Papaconstantinou Nicholas J.
Published: July 2007

The new algorithm provides closed-loop control of the LP compressor working line in such a way as to maintain compressor stability and to provide increased power from the engine at the same firing temperature. This method is intended for the Trent 60, an aeroderivative engine designated for power generation and mechanical drive applications. The power benefit is achieved by operating at higher LPC pressure ratio and thereby increasing the inlet air flow and overall pressure ratio of the engine. Since the algorithm controls the working line, the threats to compressor stability related to the working line level are removed (including production scatter, deterioration, and fouling) and the required surge margin can be safely reduced, providing a significant benefit in engine performance. The paper presents comparatively the structure of the current and new concepts, the main features of the controller, and stresses the improved accuracy and reliability of new algorithms. The performance benefit is then assessed; the increase in power is about 3% at ISO, sea level conditions and varies with ambient temperature.
Reduced-Order Modeling and Wavelet Analysis of Turbofan Engine Structural Response due to Foreign Object Damage (FOD) Events
Authors: Turso James A. , Lawrence Charles , Litt Jonathan S.
Published: July 2007

The development of a wavelet-based feature extraction technique specifically targeting FOD-event induced vibration signal changes in gas turbine engines is described. The technique performs wavelet analysis of accelerometer signals from specified locations on the engine and is shown to be robust in the presence of significant process and sensor noise. It is envisioned that the technique will be combined with Kalman filter thermal/health parameter estimation for FOD-event detection via information fusion from these (and perhaps other) sources. Due to the lack of high-frequency FOD-event test data in the open literature, a reduced-order turbofan structural model (ROM) was synthesized from a finite-element model modal analysis to support the investigation. In addition to providing test data for algorithm development, the ROM is used to determine the optimal sensor location for FOD-event detection. In the presence of significant noise, precise location of the FOD event in time was obtained using the developed wavelet-based feature.
Rotordynamic Performance of a Rotor Supported on Bump Type Foil Gas Bearings: Experiments and Predictions
Authors: Andrés Luis San , Rubio Dario , Kim Tae Ho
Published: July 2007

Gas foil bearings (GFBs) satisfy the requirements for oil-free turbomachinery, i.e., simple construction and ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal damping, as well as frequency and amplitude dependent stiffness and damping characteristics. This paper provides experimental results of the rotordynamic performance of a small rotor supported on two bump-type GFBs of length and diameter equal to 38.10mm. Coast down rotor responses from 25krpm to rest are recorded for various imbalance conditions and increasing air feed pressures. The peak amplitudes of rotor synchronous motion at the system critical speed are not proportional to the imbalance introduced. Furthermore, for the largest imbalance, the test system shows subsynchronous motions from 20.5krpm to 15krpm with a whirl frequency at ∼50% of shaft speed. Rotor imbalance exacerbates the severity of subsynchronous motions, thus denoting a forced nonlinearity in the GFBs. The rotor dynamic analysis with calculated GFB force coefficients predicts a critical speed at 8.5krpm, as in the experiments; and importantly enough, unstable operation in the same speed range as the test results for the largest imbalance. Predicted imbalance responses do not agree with the rotor measurements while crossing the critical speed, except for the lowest imbalance case. Gas pressurization through the bearings’ side ameliorates rotor subsynchronous motions and reduces the peak amplitudes at the critical speed. Posttest inspection reveal wear spots on the top foils and rotor surface.
A Novel Approach to Predicting NOx Emissions From Dry Low Emissions Gas Turbines
Authors: Syed Khawar J , Roden Kirsten , Martin Peter
Published: July 2007

An empirical modeling concept for the prediction of NOx emissions from dry low emissions (DLE) gas turbines is presented. The approach is more suited to low emissions operation than are traditional approaches (Lefebrre, A. H., 1998, Taylor and Francis, New York). The latter, though addressing key operating parameters, such as temperature and pressure drop, do not address issues such as variation in fuel/air distribution through the use of multifuel stream systems, which are commonly applied in DLE combustors to enable flame stability over the full operating range. Additionally, the pressure drop dependence of NOx in such systems is complex, and the exponent of a simple pressure drop term can vary substantially. The present approach derives the NOx model from the equations that govern the NOx chemistry, the fuel/air distribution and the dependence of the main reaction zone on its controlling parameters. The approach is evaluated through comparing its characteristics to data obtained from high-pressure testing of a DLE combustor fueled with natural gas. The data were acquired at a constant pressure and preheat temperature (14 Bara and 400°C) and a range of flame temperatures and flow rates. Though the model is configured to address both relatively fast and slow NOx formation routes, the present validation is conducted under conditions where the latter is negligible. The model is seen to reproduce key features apparent in the data, in particular, the variable pressure drop dependence without any ad hoc manipulation of a pressure drop exponent.
A FULLY DIFFERENTIAL THIRD-ORDER VHF Gm–C FILTER BASED ON LINEAR TRANSFORMATION TECHNIQUES
Authors: HWANG YUH-SHYAN , CHEN JIANN-JONG , LAI JEN-HUNG
Published: July 2007

A fully differential third-order very high frequency (VHF) Gm–C filter based on linear transformation (LT) techniques is presented in this paper. The systematic design method and the procedure are developed to realize LT Gm–C filters efficiently. A third-order Butterworth lowpass filter embedded bandgap and bias circuits with 200 MHz cutoff frequency is implemented in the TSMC 0.18 μm 1P6M process. The total harmonic distortion (THD) of the proposed filter is - 43 dB with input signal 0.5 V p-p and output loading capacitance 1 pF at 200 MHz. Power dissipation is 9.77 mW under 1.8 V supply voltage. Its core area occupies 0.188 × 0.1862. Post simulation and experimental results that confirm the theoretical analysis are obtained. Furthermore, the proposed circuits can be extended to high-order Chebychev and elliptic filters.
AN APPLICATION OF ESOP EXPRESSIONS TO SECURE COMPUTATIONS
Authors: MIZUKI TAKAAKI , OTAGIRI TARO , SONE HIDEAKI
Published: July 2007

This paper gives an application of exclusive-or sum-of-products (ESOP) expressions to designing cryptographic protocols. That is, this paper deals with secure computations in a minimal model, and gives a protocol which securely computes every function by means of the techniques of ESOP expressions. The communication complexity of our protocol is proportional to the size of an obtained multiple-valued-input ESOP expression. Since the historical research on minimizing ESOP expressions is now still active, our protocol will "automatically" turn to an efficient one as this research progresses. Thus, we hope that the existence of our cryptographic protocol would motivate further research on minimizing ESOP expressions.
ROBUST AND FAST TRACKING ALGORITHM IN VIDEO SEQUENCES BY ADAPTIVE WINDOW SIZING USING A NOVEL ANALYSIS ON SPATIOTEMPORAL GRADIENT POWERS
Authors: MOALLEM PAYMAN , MEMARMOGHADDAM ALIREZA , ASHOURIAN MOHSEN
Published: July 2007

Success of a tracking method depends largely on choosing the suitable window size as soon as the target size changes in image sequences. To achieve this goal, we propose a fast tracking algorithm based on adaptively adjusting tracking window. Firstly, tracking window is divided into four edge subwindows, and a background subwindow around it. Then, by calculating the spatiotemporal gradient power ratios of the target in each subwindow, four proper expansion vectors are associated with any tracking window sides such that the occupancy rate of the target in tracking window should be maintained within a specified range. In addition, since temporal changing of target is evaluated in calculating these vectors, we estimate overall target displacement by sum of expansion vectors. Experimental results using various real video sequences show that the proposed algorithm successfully track an unknown textured target in real time, and is robust to dynamic occlusions in complex noisy backgrounds.
Substantial working muscle glycerol turnover during two-legged cycle ergometry
Authors: Wallis Gareth A. , Friedlander Anne L. , Jacobs Kevin A. , Horning Michael A. , Fattor Jill A. , Wolfel Eugene E. , Lopaschuk Gary D. , Brooks George A.
Published: July 2007

We combined tracer and arteriovenous (a-v) balance techniques to evaluate the effects of exercise and endurance training on leg triacylglyceride turnover as assessed by glycerol exchange. Measurements on an exercising leg were taken to be a surrogate for working skeletal muscle. Eight men completed 9 wk of endurance training [5 days/wk, 1 h/day, 75% peak oxygen consumption (V̇o2peak)], with leg glycerol turnover determined during two pretraining trials [45 and 65% V̇o2peak (45% Pre and 65% Pre, respectively)] and two posttraining trials [65% of pretraining V̇o2peak (ABT) and 65% of posttraining V̇o2peak (RLT)] using [2H5]glycerol infusion, femoral a-v sampling, and measurement of leg blood flow. Endurance training increased V̇o2peak by 15% (45.2 ± 1.2 to 52.0 ± 1.8 ml·kg−1·min−1, P < 0.05). At rest, there was tracer-measured leg glycerol uptake (41 ± 8 and 52 ± 15 μmol/min for pre- and posttraining, respectively) even in the presence of small, but significant, net leg glycerol release (−68 ± 19 and −50 ± 13 μmol/min, respectively; P < 0.05 vs. zero). Furthermore, while there was no significant net leg glycerol exchange during any of the exercise bouts, there was substantial tracer-measured leg glycerol turnover during exercise (i.e., simultaneous leg muscle uptake and leg release) (uptake, release: 45% Pre, 194 ± 41, 214 ± 33; 65% Pre, 217 ± 79, 201 ± 84; ABT, 275 ± 76, 312 ± 87; RLT, 282 ± 83, 424 ± 75 μmol/min; all P < 0.05 vs. corresponding rest). Leg glycerol turnover was unaffected by exercise intensity or endurance training. In summary, simultaneous leg glycerol uptake and release (indicative of leg triacylglyceride turnover) occurs despite small or negligible net leg glycerol exchange, and furthermore, leg glycerol turnover can be substantially augmented during exercise.
Modifier locus for exencephaly inCecr2mutant mice is syntenic to the 10q25.3 region associated with neural tube defects in humans
Authors: Davidson Courtney E. , Li Qian , Churchill Gary A. , Osborne Lucy R. , McDermid Heather E.
Published: July 2007

Neural tube defects (NTDs), the second most common birth defect in humans, are multifactorial with complex genetic and environmental causes, although the genetic factors are almost completely unknown. In mice, >100 single gene mutations cause NTDs; however, the penetrance in many of these single gene mutant lines is highly dependent on the genetic background. We previously reported that a homozygous Cecr2 mutation on a BALB/c background causes exencephaly at a frequency of 74% compared with 0% on an FVB/N background. We now report that a major genetic modifier on chromosome 19, mapped using whole genome linkage analysis, increases the relative risk of exencephaly by 3.74 times in homozygous BALB embryos vs. BALB/FVB heterozygotes. Scanning electron microscopy revealed that the modifier does not affect the location of neural tube closure site 2, a known murine susceptibility factor for exencephaly. Crossing the Sp ( Splotch) mutation in the Pax3 gene onto the FVB/N background for two generations indicated that this resistant strain also decreases the penetrance of spina bifida. The chromosome 19 modifier region corresponds to a linkage region on human chromosome 10q25.3 mapped in a whole genome scan of human NTD families. Since the FVB/N genetic background affects susceptibility to both exencephaly and spina bifida, the human homolog of the chromosome 19 modifier locus may be a better candidate for human NTD susceptibility factors than genes that when mutated actually cause NTDs in mice.
Molecular Therapy in Urologic Oncology
Authors: Froehner Michael , Hakenberg Oliver W. , Wirth Manfred P.
Published: July 2007

During recent years, significant advances have been made in the field of molecular therapy in urologic oncology, mainly for advanced renal cell carcinoma. In this hitherto largely treatment-refractory disease, several agents have been developed targeting the von Hippel-Lindau metabolic pathway which is involved in carcinogenesis and progression of the majority of renal cell carcinomas. Although cure may not be expected, new drugs, such as the multikinase inhibitors sorafenib and sunitinib and the mammalian target of rapamycine inhibitor temsirolimus, frequently stabilize the disease course and may improve survival. Fewer data are available supporting molecular therapies in prostate, bladder, and testicular cancers. Preliminary data suggest a potential role of high-dose calcitriol and thalidomide in hormone-refractory prostate cancer, whereas targeted therapies in bladder and testicular cancers are still more or less limited to single-case experiences. The great theoretical potential and the multitude of possible targets and drug combinations, however, support further research into this exciting field of medical treatment of urologic malignancies.
Prostate Biopsy in Central Europe: Results of a Survey of Indication, Patient Preparation and Biopsy Technique
Authors: Fink Klaus G. , Schmid Hans-Peter , Paras Ljiljana , Schmeller Nikolaus T.
Published: July 2007

Objective: We surveyed urologists in Austria, Germany and Switzerland regarding their standard approach to prostate biopsy. Methods: Participants of Austrian and German urological meetings were asked to fill out a survey form; additionally, this was mailed to all Swiss urologists. Results: 304 surveys are available for analysis. 97% of participants perform a biopsy if digital rectal examination is abnormal. 63% use 4 ng/ml PSA (prostate-specific antigen) as cut-off. Age-related reference ranges are used by 54%, free PSA by 57%. 22% use PSA density, 55% PSA velocity. Overall 61% require a written consent, with 85, 86 and 25% in Austria, Germany and Switzerland. 96% of the urologists prescribe a quinolone antibiotic with a wide range regarding the start and end of drug therapy. 77% offer some kind of anaesthesia. Periprostatic injection of a local anaesthetic drug is used by 36%, lidocaine gel by 27%. 91% perform the biopsies transrectally under ultrasound guidance. Digitally guided biopsies are used by 11%. Only 3 participants perform perineal biopsies. The mean number of cores per biopsy session is 9.2, the maximum number of cores is 15.3 as a mean. Participants will stop performing any further biopsies if the patient already had a mean of 3.5 biopsy sessions. Conclusions: The majority of urologists in Central Europe prescribe a quinolone antibiotic and recommend some type of analgesia. The majority has abandoned the sextant technique and increases the number of cores in the case of rebiopsy. Biopsies are stopped after a mean of 3.5 sessions.
Increased Prevalence of Human T Cell Lymphotropic Virus Type 1 in Patients Attending a Brazilian Dermatology Clinic
Authors: Nobre Vandack , Guedes Antônio Carlos , Proietti Fernando Augusto , Martins Marina L. , Nassif Gabriella , Serufo José Carlos , Lambertucci José Roberto
Published: July 2007

Brazil may have the highest absolute number of individuals infected by human T cell lymphotropic virus type 1 (HTLV-1). It has been suggested that the prevalence of HTLV-1 is increased in patients with skin diseases. This study shows a higher prevalence of this infection in 1,229 patients attending a Brazilian dermatology clinic (0.7%) when compared to blood donors (0.22%). Of note, one additional patient tested positive for HTLV-2. The main skin diseases described in HTLV-1 seropositives were vitiligo (2 cases), dermatophytosis (2 cases), and leprosy (2 cases). A 23-year-old woman received a diagnosis of infectious dermatitis.