bluuebunny/crossref_metadata_2025 huggingface dataset:
PREDICTING CURRENCY CRISES WITH A NESTED LOGIT MODEL
Authors: Lau Lawrence J. , Yan Isabel K.
Published: September 2005

Abstract.  This paper is the first to apply a nested logit model to measure the probabilities of speculative attacks and the probabilities of successful defences by the central banks. This model allows us to predict the probability not only of speculative attacks but also of successful defences, given attacks. It also provides a framework for analysing the degree to which different factors affect the likelihood of attacks and defences. We find strong evidence that external illiquidity and financial fragility are reliable predictors of currency crises. The results shed light on the validity of the three generations of currency crisis models.
AN ANALYSIS OF HONG KONG EXPORT PERFORMANCE
Authors: Cheung Yin‐Wong
Published: September 2005

Abstract.  The study models the Hong Kong domestic exports and re‐exports, compares the performance of exports to the rest of the world, the USA and Japan, and uses destination‐and‐export‐type specific unit value indexes to construct real exchange rates. In general, Hong Kong exports display mean‐reverting dynamics, are positively influenced by foreign income and are adversely affected by high value of its currency. The lagged export variable, foreign income, and real exchange rate provide most of the explanatory power. Other variables explain marginally the variability of Hong Kong exports.
CHANGES IN DEMAND FUNCTION IN COURNOT OLIGOPOLY
Authors: Okuguchi Koji , Szidarovszky Ferenc
Published: September 2005

Abstract.  The effects of change in the market (inverse) demand function are systematically analysed for Cournot oligopoly without product differentiation. The general comparative‐static results are stated using the original data on firms’ cost functions and inverse demand function. Three special models are examined in light of our results. The stability condition is shown to be insufficient for determinate comparative statics.
THE SHADOW ECONOMIES OF THE ASIA‐PACIFIC
Authors: Bajada Christopher , Schneider Friedrich
Published: September 2005

Abstract.  Despite continuous government attempts to increase taxpayer compliance, the shadow economy continues to offer a way for taxpayers to evade their taxpaying obligations. The consequences are clear: policy‐makers have increasingly imperfect knowledge about the state of economic affairs as shadow economy activity expands. We provide the first known estimates of the shadow economy for 17 Asia‐Pacific countries. We show that, not only have these activities grown over the last ten years, but countries with relatively thin taxpayer compliance initiatives experience the greatest shadow economy activity.
Review of the potential photo‐cocarcinogenicity of topical calcineurin inhibitors
Authors: Ring J , Barker J , Behrendt H , Braathen L , Darsow U , Dubertret L , Giannetti A , Hawk J , Hönigsmann H , Kemeny L , Luger T , Meurer M , Murphy G , Peserico A , Ranki A , Reunala T , Saurat J , Sterry W , van de Kerkhof P
Published: September 2005

ABSTRACT  Topical Calcineurin Inhibitors (TCIs) used for the treatment of atopic eczema modify the immune regulatory function of the skin and may have the potential to enhance immunosuppressive ultraviolet (UV) effects. Current recommendations on UV protection in eczema patients treated with PCIs are inconsistent and have given rise to uncertainty and anxiety in patients. Therefore, the European Dermatology Forum (EDF) developed a position statement which reviews critically the available data with regard to the problem, especially analysing and commenting the limitations of rodent models for the human situation. There is no conclusive evidence from rodent trials to indicate that long‐term application of TCIs is photococarcinogenic. There is a need for further studies to investigate the validity of mouse models as well as long‐term cohort studies in patients using TCIs. Available data suggest that long‐term application of TCIs is safe, that there is no evidence of increased skin cancer risk and that it is ethical to treat patients with TCIs when indicated.
Can Transthoracic Echocardiography with Subcostal View Predict Abdominal Aortic Atherosclerosis?
Authors: Ahmed Sujood , Rehan Arshad , Ahmad Israr , Gardin Julius M. , Nanda Navin C. , Cohen Gerald I.
Published: September 2005

Background: Prompt detection of atherosclerosis (ATH) may profoundly impact therapy and patient outcome. During transthoracic echocardiography (TTE), subcostal views may suggest abdominal (ABD) aortic (AO) ATH, but this diagnosis may be inaccurate due to suboptimal images, which may in part relate to use of nonlinear probes. Therefore, we investigated the accuracy of TTE assessment of ABD AO ATH relative to transesophageal (TEE) AO images. Methods: Routine clinical TTE and TEE studies of 100 patients (44 men), aged 30–92 years old, were reviewed retrospectively and blindly. ABD AO ATH by TTE was graded qualitatively as grade (GR) 0 = smooth wall surface; GR 1, 2, and 3 = mild, moderate, and severe irregularities, respectively; and GR 4 = mobile/complex plaque. TEE images were graded quantitatively as the maximal intimal‐medial, or plaque thickness, imaged in the AO arch or descending AO, as: GR 0 ≤ 1.5 mm, GR 1 = 1.5–2.4 mm, GR 2 = 2.5–4 mm, GR 3 = >4 mm, or GR 4 = mobile/complex plaque >4 mm. TTE ability to detect the presence (>GR 0) of ABD AO ATH on TEE was measured in terms of sensitivity (SN), specificity (SP), positive (PPV) and negative (NPV) predictive accuracy—in patients with adequate and suboptimal images—compared to TEE. Results: TTE image quality was adequate in 75 patients and suboptimal in 25. SP and PPV of grading ATH by TTE were directly related to grading by TEE; however, SN and NPV demonstrated an inverse relationship with increasing grading of ATH. TTE correlated with TEE grading with an r = 0.42 (P = 0.0001) for patients (n = 75) with adequate TTE and r = 0.32 (P = 0.001) for all patients (n = 100), including those with suboptimal TTE images. Conclusion: Routine TTE imaging is usually correct in predicting ATH on TEE, but with modest error, it should generally not be relied on as a definitive test for ATH. Adequate image quality improves the correlation of TEE and TTE grading of ABD ATH, and more severe ATH on TTE is more predictive of ATH on TEE.
Pulmonary Vein Compression by Tumor: An Unusual Doppler Flow Pattern
Authors: Chen Carol L. , Tunick Paul A. , Kronzon Itzhak
Published: September 2005

Pulmonary venous compression caused by a large lung mass was diagnosed in a 50‐year‐old female with metastatic renal cell carcinoma. The pulmonary venous flow pattern on Doppler revealed high flow velocity as well as the unusual finding of continued antegrade flow throughout the cardiac cycle (without reversal during atrial contraction). Extracardiac tumors can compress pulmonary veins, mimicking pulmonary vein stenosis. This may cause dyspnea due to elevated pulmonary venous pressures. This report describes an unusual pulmonary vein blood flow pattern in a patient with lung metastases.
Impaired Coronary Circulation in Patients with Apical Hypertrophic Cardiomyopathy: Noninvasive Analysis by Transthoracic Doppler Echocardiography
Authors: Yoshida Ken , Hozumi Takeshi , Takemoto Yasuhiko , Sugioka Kenichi , Watanabe Hiroyuki , Muro Takashi , Yoshiyama Minoru , Takeuchi Kazuhide , Yoshikawa Junichi
Published: September 2005

Objectives: We designed this study to examine the characteristics of coronary circulation in patients with apical hypertrophic cardiomyopathy (ApHCM) using noninvasive transthoracic Doppler echocardiography (TTDE). Background: Recent advances in TTDE have allowed noninvasive assessment of coronary circulation by the measurement of coronary flow velocity (CFV) patterns and coronary flow velocity reserve (CFVR). However, there have been no previous studies evaluating coronary circulation in ApHCM. Methods: We analyzed CFV and CFVR in the left anterior descending coronary artery (LAD), and apical wall thickness in the left ventricle, in 10 ApHCM subjects and 10 control subjects. Mean diastolic velocity (MDV) and time from the beginning of diastole to peak velocity (TPV), and CFVR, defined as a ratio of drug‐induced hyperemic to basal MDV, were measured. Results: At baseline, MDV was higher, and TPV was longer, in ApHCM subjects than in control subjects (29 ± 5.7 versus 19 ± 6.5 cm/sec; p < 0.01 and 5.2 ± 1.0 versus 3.5 ± 0.6 msec; p < 0.005, respectively). CFVR in ApHCM subjects was significantly lower than in control subjects (1.9 ± 0.4 versus 3.1 ± 0.8; p < 0.005). CFVR and basal MDV in ApHCM subjects showed significant correlations with apical/posterior wall thickness ratio [CFVR; r =–0.84, p < 0.01 and MDV; r = 0.74, p < 0.05, respectively].Conclusion: Noninvasive coronary flow assessment by TTDE revealed an impaired coronary circulation with reduced CFVR, high MDV at baseline and prolonged TPV. These results suggest that these characteristics of coronary circulation may provide an additional index for the assessment of ApHCM.
Left Ventricular Tei Index: Comparison between Flow and Tissue Doppler Analyses
Authors: Voon Wen‐Chol , Su Ho‐Ming , Yen Hsueh‐Wei , Lin Tsung‐Hsien , Lai Wen‐Ter , Sheu Sheng‐Hsiung
Published: September 2005

Background: It is still unknown whether a correlation exists between left ventricular Tei index obtained by tissue Doppler imaging and that determined by flow Doppler waveforms. This study was conducted to evaluate their relationship and to assess the positional effect on them. Methods: Twenty‐six healthy subjects and 25 patients with essential hypertension were included. On the tissue Doppler images, the time interval from the end to the onset of the mitral annular velocity pattern during diastole and the duration of the S‐wave were used to calculate tissue Doppler Tei index. Results: The tissue Doppler Tei index correlated with the flow Doppler Tei index at sitting position (r = 0.406, P = 0.003), but not at left lateral decubitus position. The limits of agreement for the Tei index measured by both methods were −0.26 to 0.62 at left lateral decubitus position and −0.09 to 0.55 at sitting position. Preload reduction associated with sitting position with dangling feet raised the Tei index both in the healthy controls [0.54 (0.14) vs 0.42 (0.12), P < 0.001] and in the hypertensives [0.53 (0.15) vs 0.46 (0.12), P = 0.005]. There was a similar positional effect on the tissue Doppler Tei index in the control subjects [0.75 (0.12) vs 0.53 (0.10), P < 0.001]. Conclusions: Tissue Doppler Tei index does not seem to be a suitable substitute for flow Doppler Tei index. Flow Doppler Tei index is preload dependent and the loading status should be taken into consideration at the application of Tei index to the evaluation of myocardial performance.
Detection of Discrete Subaortic Stenosis by 3‐Dimensional Transesophageal Echocardiography
Authors: Miyamoto Koji , Nakatani Satoshi , Kanzaki Hideaki , Tagusari Osamu , Kobayashi Junjiro
Published: September 2005

We present a case with discrete subaortic stenosis diagnosed by 2D and 3D echocardiography. 3D echocardiography was useful to demonstrate its morphology and dynamic change of the left ventricular outflow tract area, providing important information for surgical intervention.
Asymptomatic Hyperleukocyturia in Hemodialysis Patients Analyzed by the Automated Urinary Flow Cytometer
Authors: Hyodo Toru , Yoshida Kazunari , Sakai Tadasu , Baba Shiro
Published: September 2005

Abstract:  The number of urinary white blood cells (WBC) is useful marker of urinary tract infection in patients without renal insufficiency. On the other hand, it is unclear what urinalysis data are normal in hemodialysis (HD) patients. The occurrence and numbers of WBC in 75 asymptomatic HD patients and 133 healthy individuals as controls were determined by the automated urinary flow cytometer (UF‐100, Sysmex Co., Kobe, Japan). The finding of hyperleukocyturia (>10 WBC per high power field of 400 × microscopic magnification) was observed in 46.7% of HD patients. Urinary WBC significantly increased with decrease in the urinary volume. It may not be appropriate to indiscriminately apply the diagnostic criteria of pyuria for patients with normal renal function to dialysis patients because the number of urinary WBC was closely related to the urinary volume in HD patients.
The role of an international apheresis registry for the establishment of apheresis therapy
Authors: Stegmay BG , Guillevin L , Korach JM , Rock G , Norda R , Ramlow W
Published: September 2005

Since apheresis may be performed in many different ways for many different indications world wide the World Apheresis Association (WAA) decided to start a registry. The aim of the registry is to improve knowledge about indications, techniques and adverse events to optimize information and therapy of the patients. In addition the knowledge will be helpful for industry to further develop devices and bring them into market. In December 2002, WAA launched such world‐wide apheresis registry to gain insight into the extent of treatment, adverse events, and to facilitate contacts among centers when treatment indications are rare and experience limited. Apheresis procedures to collect stem cells and other blood products, intended for clinical application, should also be able to enter. Since then several centers and countries have entered the registration procedure. Each centre at the end of the year gets a file of their own data for own statistics. We now cordially invite also other centers to join the registry. Please, also inform colleagues at other centers in your country to join. E‐mail and address lists of colleagues in your country who have not registered will be welcomed. The site is available at: http://www.iml.umu.se/medicin/. Go to World Apheresis Registry; Login code to test the Registry is: al61tms (AL61TMS). Then apply for a specific login code for your center. We welcome you to this registry for your input of data. You will not be charged any registration fee. At the moment the site is also under development to facilitate registrations and feed back. In the future the registry is planned to include information about indications, techniques and various interactive approaches.
World apheresis registry: report of 2004 data
Authors: Stegmayr B , Ptak J , Wikström B , Berlin G , Axelsson CG , Griskevicius A , Centoni P , Liumbruno G , Audzijoniene J , Mokvist K , Nilsson Sojka B
Published: September 2005

Centers from 9 countries have applied for a login code to the WAA apheresis registry. Of these 9 centers from 4 countries have been actively entering data during 2004. Registered are at the moment a total of 347 patients (55% women, mean age 54 y, and 45% men, mean age 52 y). Main indications were neurological (33%), vasculitis (9%), and lipid apheresis (8%). In 92% of the patients therapeutic apheresis was performed while in 8% retrieval of components was the reason. A total of 1808 procedures were registered. More than 88% of the patients had acute indications. Access was mainly by peripheral vessels (65%), central dialysis catheter through jugular route (11%) or subclavian (9.4%) while femoral vein and AV fistula were used in 4.3 versus 0.5% of occasions. Anticoagulation was performed by ACD (80.5%), CPD citrate (2.5%), ACD and heparin (7%), ACD and LMW heparin (4%) and only heparin (5.8%). Replacement fluids for therapeutic apheresis removing plasma was mainly by albumin (85%) while plasma (22%) and cryoprecipitate poor plasma (5%) was used to less extent. Adverse events (AE) were registered in 6% of procedures. Distribution was for mild AE (1.4%), moderate (3.4%) and severe (0.6%) In 21 treatments there were 2 AEs while in 2 patients there were 3 AEs. Most frequent AEs were hypotension (35%), tingling around the mouth (24%), chill and fever (5.5%) and urticaria (5.5%). There were significant differences between the centers. The incidence of hypotension varied between 0.36–3.23% between centres. There was no significant difference in severe AEs between the centres. Main procedure used was centrifugation technique for conventional plasma exchange by centrifugation or filtration, while other modes were leukapheresis, erythrapheresis, platelet apheresis, LDL‐apheresis, photopheresis and adsorption. Conclusion: Data from the registry show that centres have various approaches to apheresis. One can learn from each others experience to reduce side effects and improve efficacy.
Treatment of renal diseases with plasma exchange: a single center experience
Authors: Nenov Kiril , Stoyanov Alexander , Paskalev Dobrin
Published: September 2005

Over the last decades, plasma exchange (PE) has been applied in the treatment of over 150 different diseases including nephrological, hematological, neurological, and rheumatological. Clinical benefit has been demonstrated in only about 40 of them and the best results were achieved in diseases with pathogenic autoimmune mechanisms. We used PE most frequently in patients with immune and autoimmune nephropathies aiming to decrease pathologically elevated antibody levels, autoantibodies and immune complexes. PE was applied in 40 patients with chronic glomerulonephritis, 29 patients with lupus nephritis, and 9 patients with Schoenlein‐Henoch nephritis. After 3 to 4 PE sessions, continuous immunosuppressive drug therapy was initiated. Significant reduction of antibody titers and immune complexes was achieved. PE was also applied in 45 plasmacytoma patients with nephropathy to reduce plasma viscosity and slow down the progression of myeloma nephropathy. The result was a significant reduction of pathologically elevated plasma viscosity and a detoxification effect. In our clinic plasma exchange procedures were performed by either centrifugal method with Haemonetics M‐30 device or by plasma filtration. An average of 1316 mL plasma was removed during a PE session. For substitution purposes donor plasma and saline solutions were used. Clinical remission was achieved in 61.3% of all patients without slowing the progression of renal failure, however.
Does LDL contribute to Viscosity?
Authors: Schuff‐Werner Peter , Lehmann‐Holdt Birgit
Published: September 2005

There is a large body of evidence that large plasma proteins such as fibrinogen, IgM and alpha2‐macroglobulin contribute to plasma viscosity. Although familial hypercholesterolemia (FH) is often associated with hyperfibrinogenemia, elevated viscosity in FH patients independent from fibrinogen plasma levels was communicated in the literature. Selective LDL‐apheresis such as Apo‐B‐100 immunoadsorption, dextran sulfate adsorption and heparin‐induced extracorporeal LDL‐precipitation (HELP) are effective tools for investigating the effect of selective elimination of LDL and/or fibrinogen on viscosity. The decrease in viscosity during selective LDL‐apheresis was correlated to the differences in LDL and/or fibrinogen concentrations. Regression analysis of data obtained from 12 FH patients shows a strong correlation between LDL‐cholesterol and viscosity (r = 0.6892; P < 0.001). Fibrinogen is also correlated with viscosity (r = 0.5433; P < 0.001). The slope of LDL/viscosity regression shows a 5‐fold difference (0.00097 vs. 0.00018) for LDL and fibrinogen, respectively, thus demonstrating a strong contribution LDL‐cholesterol on viscosity.
IP3‐mediated Ca2+ increases do not involve the ryanodine receptor, but ryanodine receptor antagonists reduce IP3‐mediated Ca2+ increases in guinea‐pig colonic smooth muscle cells
Authors: MacMillan Debbi , Chalmers Susan , Muir Thomas C. , McCarron John G.
Published: September 2005

Smooth muscle responds to IP3‐generating (sarcolemma acting) neurotransmitters and hormones by releasing Ca2+ from the sarcoplasmic reticulum (SR) via IP3 receptors (IP3Rs). This release may propagate as Ca2+ waves. The Ca2+ signal emanating from IP3 generation may be amplified by its activating further Ca2+ release from ryanodine receptors (RyRs) in the process of Ca2+‐induced Ca2+ release (CICR). Evidence for this proposal has relied largely on the use of blocking drugs such as ryanodine, tetracaine and dantrolene, reportedly specific inhibitors of RyRs. Here we have examined whether or not Ca2+ released via IP3Rs subsequently activates RyRs. In addition, the specificity of the blocking agents has been assessed by determining the extent of their ability to block IP3‐mediated Ca2+ release under conditions in which RyRs were not activated. IP3‐evoked Ca2+ release and Ca2+ waves did not require or activate RyRs. However, the RyR blocking drugs inhibited IP3‐mediated Ca2+ signals at concentrations thought to be selective for RyRs. In single colonic smooth muscle cells, voltage clamped in the whole cell configuration, carbachol (CCh) evoked propagating Ca2+ waves which were not inhibited by ryanodine when the sarcolemma potential was −70 mV. At −20 mV, at which potential the SR Ca2+ content was increased and RyRs activated, ryanodine inhibited the Ca2+ waves. Photolysed caged IP3 increased [Ca2+]c; ryanodine, by itself, did not reduce the IP3‐evoked [Ca2+]c increase when the sarcolemma potential was maintained at −70 mV. However, after activation of RyRs by caffeine, in the continued presence of ryanodine, the IP3‐evoked [Ca2+]c increase was inhibited. In other experiments, RyRs were activated (as evidenced by the occurrence of spontaneous transient outward currents) by depolarizing the sarcolemma to −20 mV and again ryanodine was effective in inhibiting IP3‐evoked Ca2+ increase. Thus while ineffective by itself, ryanodine inhibited IP3‐evoked Ca2+ increases, presumably by causing persistent opening of the channel and depleting the SR of Ca2+, after RyRs were activated. These experiments establish that IP3‐evoked Ca2+ release and Ca2+ waves do not activate RyRs; had they done so ryanodine would have inhibited the Ca2+ increase. However, under conditions where ryanodine was ineffective against the IP3‐evoked Ca2+ transient (i.e. when RyRs were not activated, e.g. at a membrane potential of −70 mV) tetracaine and dantrolene each blocked IP3‐evoked Ca2+ increases. The results show that although IP3‐mediated Ca2+ release does not activate RyRs, RyR blockers can inhibit IP3‐mediated Ca2+ signals.
Signal transduction pathways and gating mechanisms of native TRP‐like cation channels in vascular myocytes
Authors: Albert A. P. , Large W. A.
Published: September 2005

Activation of Ca2+‐permeable non‐selective cation channels produces an increase in excitability of vascular smooth muscle cells which has an important role in vasoconstriction. These channels are activated by various physiological stimuli including vasoconstrictor agents such as noradrenaline, depletion of internal Ca2+ stores and cell stretching. In addition cation channels have been shown to be constitutively active and these channels are thought to contribute to resting membrane conductance and basal Ca2+ influx in vascular myocytes. Recent evidence has suggested that transient receptor potential (TRP) proteins represent strong candidates for these channels in the vasculature. This review discusses proposed signal transduction pathways and gating mechanisms which link physiological stimuli to opening of cation channels in vascular myocytes. It is apparent that G‐protein‐coupled pathways linked to stimulation of phospholipase activity have a profound effect on regulating channel activity and that generation of diacylglycerol (DAG) is a central event in these signalling cascades with this triglyceride having a pivotal role in gating cation channels via both PKC‐independent and ‐dependent mechanisms. Moreover phosphorylation processes produced by stimulation of protein kinases have been proposed to have an important role in regulating cation channel activity.
A leucine‐supplemented diet restores the defective postprandial inhibition of proteasome‐dependent proteolysis in aged rat skeletal muscle
Authors: Combaret Lydie , Dardevet Dominique , Rieu Isabelle , Pouch Marie‐Noëlle , Béchet Daniel , Taillandier Daniel , Grizard Jean , Attaix Didier
Published: September 2005

We tested the hypothesis that skeletal muscle ubiquitin–proteasome‐dependent proteolysis is dysregulated in ageing in response to feeding. In Experiment 1 we measured rates of proteasome‐dependent proteolysis in incubated muscles from 8‐ and 22‐month‐old rats, proteasome activities, and rates of ubiquitination, in the postprandial and postabsorptive states. Peptidase activities of the proteasome decreased in the postabsorptive state in 22‐month‐old rats compared with 8‐month‐old animals, while the rate of ubiquitination was not altered. Furthermore, the down‐regulation of in vitro proteasome‐dependent proteolysis that prevailed in the postprandial state in 8‐month‐old rats was defective in 22‐month‐old rats. Next, we tested the hypothesis that the ingestion of a 5% leucine‐supplemented diet may correct this defect. Leucine supplementation restored the postprandial inhibition of in vitro proteasome‐dependent proteolysis in 22‐month‐old animals, by down‐regulating both rates of ubiquitination and proteasome activities. In Experiment 2, we verified that dietary leucine supplementation had long‐lasting effects by comparing 8‐ and 22‐month‐old rats that were fed either a leucine‐supplemented diet or an alanine‐supplemented diet for 10 days. The inhibited in vitro proteolysis was maintained in the postprandial state in the 22‐month‐old rats fed the leucine‐supplemented diet. Moreover, elevated mRNA levels for ubiquitin, 14‐kDa ubiquitin‐conjugating enzyme E2, and C2 and X subunits of the 20S proteasome that were characteristic of aged muscle were totally suppressed in 22‐month‐old animals chronically fed the leucine‐supplemented diet, demonstrating an in vivo effect. Thus the defective postprandial down‐regulation of in vitro proteasome‐dependent proteolysis in 22‐month‐old rats was restored in animals chronically fed a leucine‐supplemented diet.
Interaction of Shroud Leakage Flow and Main Flow in a Three-Stage LP Turbine
Authors: Gier Jochen , Stubert Bertram , Brouillet Bernard , de Vito Laurent
Published: September 2005

Endwall losses significantly contribute to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratios are increased. In turbines with shrouded airfoils a large portion of these losses are generated by the leakage flow across the shroud clearance. Generally the related losses can be grouped into losses of the leakage flow itself and losses caused by the interaction with the main flow in subsequent airfoil rows. In order to reduce the impact of the leakage flow and shroud design related losses a thorough understanding of the leakage losses and especially of the losses connected to enhancing secondary flows and other main flow interactions has to be understood. Therefore, a three stage LP turbine typical for jet engines is being investigated. For the three-stage test turbine 3D Navier-Stokes computations are performed simulating the turbine including the entire shroud cavity geometry in comparison with computations in the ideal flow path. Numerical results compare favorably against measurements carried out at the high altitude test facility at Stuttgart University. The differences of the simulations with and without shroud cavities are analyzed for several points of operation and a very detailed quantitative loss breakdown is presented.
Flow Mechanism for Stall Margin Improvement due to Circumferential Casing Grooves on Axial Compressors
Authors: Shabbir Aamir , Adamczyk John J.
Published: September 2005

A computational study is carried out to understand the physical mechanism responsible for the improvement in stall margin of an axial flow rotor due to the circumferential casing grooves. Computational fluid dynamics simulations show an increase in operating range of the low speed rotor in the presence of casing grooves. A budget of the axial momentum equation is carried out at the rotor casing in the tip gap in order to understand the physical process behind this stall margin improvement. It is shown that for the smooth casing the net axial pressure force at the rotor casing in the tip gap is balanced by the net axial shear stress force. However, for the grooved casing the net axial shear stress force acting at the casing is augmented by the axial force due to the radial transport of axial momentum, which occurs across the grooves and power stream interface. This additional force adds to the net axial viscous shear force and thus leads to an increase in the stall margin of the rotor.
Effect of Hole Geometry on the Thermal Performance of Fan-Shaped Film Cooling Holes
Authors: Gritsch Michael , Colban Will , Schär Heinz , Döbbeling Klaus
Published: September 2005

This study evaluates the impact of typical cooling hole shape variations on the thermal performance of fan-shaped film holes. A comprehensive set of experimental test cases featuring 16 different film-cooling configurations with different hole shapes have been investigated. The shape variations investigated include hole inlet-to-outlet area ratio, hole coverage ratio, hole pitch ratio, hole length, and hole orientation (compound) angle. Flow conditions applied cover a wide range of film blowing ratios M=0.5 to 2.5 at an engine-representative density ratio DR=1.7. An infrared thermography data acquisition system is used for highly accurate and spatially resolved surface temperature mappings. Accurate local temperature data are achieved by an in situ calibration procedure with the help of thermocouples embedded in the test plate. Detailed film-cooling effectiveness distributions and discharge coefficients are used for evaluating the thermal performance of a row of fan-shaped film holes. An extensive variation of the main geometrical parameters describing a fan-shaped film-cooling hole is done to cover a wide range of typical film-cooling applications in current gas turbine engines. Within the range investigated, laterally averaged film-cooling effectiveness was found to show only limited sensitivity from variations of the hole geometry parameters. This offers the potential to tailor the hole geometry according to needs beyond pure cooling performance, e.g., manufacturing facilitations.
Masking of Tones by Bands of Noise
Authors: Bilger R. C. , Hirsh I. J.
Published: September 2005

Measurements were made of the masking of pure tones by bands of noise, the width of each band corresponding to a pitch interval of 250 mels, with band level varied from 40 to 120 db SPL. The masked audiograms were compared to the frequency characteristics of the bands of noise. It was found that published values for the critical bands predict the masking for tone within the band. More masking than would be predicted is found for the frequencies above a band. Below the band, the masked threshold is again predicted precisely by the critical-band hypothesis, but only to a point beyond which, for high noise levels, a “remote” masking, which is constant as a function of frequency for any particular level, is observed and is much more than can be predicted from the effective levels (from either system noise or imperfect filtering) obtaining at those low frequencies where this masking is observed. Whereas for tone within the band masking increases linearly with level, this “remote” masking rises in an accelerated manner with level and then decelerates at the highest levels. Some speculative interpretation is attempted. [This work was supported under Contract No. AF 18(600)-131 with the U. S. Air Force.]
Small Volume Tuned Acoustic Filters for Reciprocating Compressors
Authors: Leeper Charles K. , Raymond Priscilla M.
Published: September 2005

Design features of an acoustic filter for use on suction and discharge of constant speed reciprocating gas compressors are presented. The filter derives its high attenuation per unit filter volume from use of Helmholtz resonators, rather than simple compliances or quarter-wavelength tubes, in shunt branches. Direct current pressure losses are relatively small because series elements are inductive in nature. Cylinder starvation is minimized by presenting essentially equivalent impedances to all compressor cylinders. Experimental data are compared with theoretical performance predictions for an installation involving 900 horsepower compressors. In this installation a typical filter through-put time (total filter volume/steady flow volume rate) is 0.47 second, and the fundamental frequency is 8.5 cps.
Noise from Centrifugal Fans
Authors: Allen Clayton H.
Published: September 2005

Early studies [J. Acoust. Soc. Am. 25, 313 (1953); J. Acoust. Soc. Am. 25, 322 (1953)] related noise output to fan horsepower and indicated the usefulness of this relation in predicting noise in ventilating systems. More comprehensive measurements yielded a simpler, more accurate equation relating noise and rated horsepower for large centrifugal fans in actual air conditioning installations [J. Acoust. SOC. Am. 27, 217 (1955)]. The present paper shows that recent laboratory measurements of noise from small centrifugal fans [Noise Control 1, No. 6, 26 (November, 1955)] is consistent with the relation found for large fans. In addition, empirical equations derived for the small fans expressing total noise as the sum of two parts, one arising from air flow and one from static head, can be simplified with improved fit to the data Pf = C1V5 and PH = C2H3(WH/WR)5, where Pf and PH are noise power resulting from flow and static head, respectively; C1 and C2 are constants; V is a linear velocity equal to the volume flow of discharge air divided by the area of the outer cylindrical surface of the rotor; H is static head; and WR and WH are widths of rotor and housing, respectively. These equations indicate that an optimum relation exists between air speed and pressure head which will minimize noise for a given horsepower delivered from a fan of a given size. Comparisons of these relations to subsequent data for large fans will be made.
Analog Computation of Probe Microphone Response
Authors: Leonard Robert W.
Published: September 2005

The expression for the ratio of the pressure at the microphone to the pressure at the probe tip can be written most concisely in terms of hyperbolic functions of a complex argument containing the frequency, probe length, and implicitly the acoustic impedances of the probe tube and terminal components. The resulting expression is sufficiently complicated to make point by point calculations rather tedious except for a few specialized cases. Computation on an electrical analog is a relatively simple matter if only the amplitude ratio is required. A simple combination of a delay line and lumped elements will be described which simulates with reasonable accuracy the acoustic system over its useful frequency range.
The Modern Russian Sentence Intonation as a Linguistic Structure
Authors: Buning J. Erna Jurgens , van Schooneveld Cornelius H.
Published: September 2005

A code of intonational features was found which, if substituted for one another in the message, entail a change in the information carried by the sentence, viz., (a) a fall of a fifth to the tonic of the underlying musical key, i.e., a decrease of fundamental frequency in the proportion 3:2, from the immediately preceding syllable to the last stressed syllable characterizes the statement; (b) a rise of a third from the underlying tonic, i.e., an increase of frequency in the proportion 5:6 from the last stressed syllable to the next syllable, characterizes the question (when no interrogative pronoun or particle is used). In a large sentence additional constant characteristic intervals (i.e., proportions in frequency) precede. The interval constants characterizing larger statements are contextual variants of the basic type: the fall of a fifth to the tonic. Sentences containing contrastive stress have larger intervals; their form can easily be derived from the intonation patterns of comparable sentences without contrastive stress. The tone on which a single syllable is spoken can be interpreted only by juxtaposition with the other syllable tones of the sentence. Thus the musical concepts of key, degree, and interval, which superimpose upon the chromatic spectrum of musical tones a limit of choice, become relevant for the interpretation of sentence intonation.
Measurement of the Fundamental Period of Speech Using a Delay Line
Authors: Miller R. L. , Weibel E. S.
Published: September 2005

This method makes use of the fact that the voiced portion of a speech signal is very nearly periodic in time, the period being the inverse of the fundamental frequency. If a periodic wave is delayed by exactly one period and then subtracted from the original wave, the result is zero. If the delay is other than a multiple of the period, the result is in general not zero. To implement this principle, speech is passed through a tapped delay line and the output of each tap is subtracted from the undelayed signal. If the voltages thus obtained are time averaged and then scanned, a wave results which shows a null at the tap corresponding to the period. In the case of unvoiced sounds a null will not appear, so that voiced and unvoiced sounds can be differentiated.
Scattering in an Infinitely Extended Inhomogeneous Medium
Authors: Skudrzyk Eugen
Published: September 2005

Scattering in a medium containing patches of inhomogeneities consists of a splitting up of the incident sound into incoherent waves as well as of a focusing and defocusing action of the inhomogeneities. The first phenomenon causes rapidly varying interferences leading to an amplitude distribution between Gaussian and Rayleigh; the second causes a slow spreading of this amplitude distribution toward lower and higher values of sound pressure. The interference component can be derived from a simple model consisting of infinite slabs having properties similar to those of the patches of inhomogeneity along the line connecting source and receiver; the focusing component follows from a consideration of the divergence of a beam caused by refraction. The pressure scattered in the forward direction is out of phase by 90 degrees with respect to the unscattered sound and causes only a change of phase when the patches are large; but when the patches are small, the scattered pressure is found to be Rayleigh distributed and to affect the amplitude as well as the phase of the transmitted sound. With the aid of results derived by Potter and Murphy (Applied Physics Laboratory, University of Washington, APL/UW/TE/55-12), the total pressure and its fluctuation can be computed for any frequency and any size of the scattering patches. The maximum radius “a” of a patch sensibly contributing to the intensity at a distance r is found to be given by a + (r/k)12, where k is the wave number. With increasing frequency, scattering turns from a first-order to a second-order phenomenon, so that finally we are left with focusing effects as given by ray theory. The usual practice connecting the correlation function with the intensity proves to be applicable only when the frequency is low or the patches are small and leads to completely wrong results for higher frequencies or for larger patches.
On the Diffusion of Sound Waves in a Turbulent Atmosphere
Authors: Lyon Richard H.
Published: September 2005

The diffusion of sound waves in a homogeneous, isotropic turbulent medium is discussed. The spectrum of the turbulence in wave number and frequency is assumed to be of the form E(k,ω)∼λλ2+ω2k4e−4k/k0. Here, k0 is the wave number of the energy-bearing eddies and 1/λ is the autocorrelation period of the turbulence. This spectrum produces a diffusion of the sound wave in both direction and frequency, as the wave progresses. The quantity λ is evaluated by analogy with the harmonic oscillator which is excited by random noise. The autocorrelation time in this case is given by τ ≡ average energy stored/average energy lost per second, which for the case of turbulence is 1/λ = 〈u2〉/ε = 8/15νk02, where ν = kinematic viscosity. The autocorrelation times as evaluated in this way are compared with those measured in turbulent flow. The limitation of speech intelligibility out of doors by the effect of the frequency diffusion will also be discussed. [Supported by Contract NAw-6463 with the National Advisory Committee for Aeronautics.]
Results of a Study of the Influence of Weather upon Sound Propagation
Authors: Benson Robert W. , Karplus Henry B.
Published: September 2005

As a result of measurements on the propagation of sound through the atmosphere near the earth's surface, data will be presented representing the conclusions from more than 250 flying hours. Measurements have been made during a continuous period of one year including a range of weather conditions existing from winter to summer. Complete distribution functions of sound propagation will be given as a function of frequency (i.e., for various octave bands) for various angles with respect to the earth's surface. In addition correlations have been performed to illustrate the dependence of propagation upon various meteorological factors. The influence of wind velocity, gradient and direction, temperature, temperature gradient, barometric pressure, humidity, time of day, and time of year will be discussed in relationship to sound propagation. Results will be given for those factors which appear to influence the propagation of sound. [This research was supported by U. S. Air Force Contract AF33 (616)-2470.]
Vertical Atmospheric Transmission from a Moving Sound Source
Authors: Martin D. W. , Duncan R. K. , Murphy R. L.
Published: September 2005

Vertical transmission of sound through a considerable thickness of atmosphere from a rapidly moving source is seriously hampered by a number of factors including Doppler effect, normal attenuation with distance, high-frequency absorption in the medium, random fluctuations in level (probably caused by turbulence), and the effect of source speed upon the fluctuations. The present investigation did not attempt to investigate all of these factors in detail, but gave results indicating their relative importance to the transmission of speech sounds. In the experiments particular attention was given to the differences in the properties of the transmitted wave near and far from the source. [Work done under government contracts AF33 (038)-23313 and AF33 (616)-2320.]
Equal-Loudness Relations, and Threshold of Hearing for Pure Tones
Authors: Robinson D. W. , Dadson R. S.
Published: September 2005

A redetermination of the equal-loudness relations for pure tones in free field has been completed recently at the National Physical Laboratory, with the aim of resolving the discrepancies between former determinations and of providing an improved basis for the establishment of standard equal-loudness contours. The new results apply to a large team of otologically normal persons, and cover the range from 25 to 15 000 cps and up to 130 db in sound-pressure level. Extension to the highest sound-pressure levels was made possible by the use of improved techniques. The data are more regular than the former results, and throw light on some of the earlier discrepancies. The equivalent loudness of any pure tone is found to be expressible by formulas quadratic in the sound-pressure level, with coefficients varying smoothly with frequency. Effects of age on the results at the higher frequencies are considered. The work includes a new determination of the threshold of hearing in free field which is very consistent with the equal-loudness relations, and with a previous investigation by the National Physical Laboratory of the threshold of hearing for listening by earphone.
Fractional versus Multiple Loudness Measurements
Authors: Ham Lloyd B.
Published: September 2005

Loudness measurements at the University of Arkansas using about 400 students to obtain nearly 5000 judgments, yield results comparable to those reported in 1932 [J. Acoust. Soc. Am. 3, 511 (1932)] with one significant difference. When fractional loudness judgments are separated from multiple loudness judgments, the following results are obtained: fractional loudness judgments of 12, 13, and 15 are obtained with decibel reductions of 8.4, 14.3, and 20.8; multiple loudness judgments of 2, 3, and 5 times are obtained with decibel increases of 8.6, 17.7, and 24.8. In certain masking experiments with deafened ears [with J. Guttman, J. Acoust. Soc. Am. 2, 83 (1930), Arch. Otolaryngol. 12, 425 (1930)] the authors concluded that the ear possesses a sensitive mechanism for damping strong, unpleasant sounds in some manner. The present loudness experiments, compared with the former masking experiments, suggest again the reality of such a damping mechanism. The results indicate that differences between fractional and multiple loudness judgments may not be expected until changes in loudness is in excess of two (or one-half) times the reference sound level, due to a lack of obtainable experimental accuracy.
Evaluation of Two Loudness Computational Procedures for Broad-Band Noises
Authors: Pollack Irwin
Published: September 2005

Two loudness computational procedures for octave-band analyses of broad-band noises were examined in terms of their ability to predict equal-loudness adjustments. The first procedure employs the 1942 American Standard loudness function, pure-tone equal-loudness contours, and assumes complete additivity of loudness. The second procedure employs a slightly modified loudness function, octave-band noise equal-loudness contours, and assumes only partial additivity of loudness. The procedures were evaluated against equal-loudness adjustments between each of nine spectral noises and a wide-band “white” noise. The nine spectral noises were produced by passing white noise through a series of frequency emphasis, or tilting, circuits ranging from −12 db to +12 db per octave spectral tilt. The first procedure systematically overestimates the loudness of low-frequency noise spectra and underestimates the loudness of high-frequency noise spectra. A substantial portion of the systematic discrepancy of the first procedure is removed by re-evaluating the loudness of the highest noise frequencies (4.8 to 9.6 kc) in line with the octave-band noise contours. The second procedure avoids the systematic errors of the first procedure and substantially improves the over-all accuracy of loudness prediction—reducing the decibel error by about 2 to 1.
Review of the Netherlands Study of Noise Control in Multiple Dwellings
Authors: van den Eijk J. , Kasteleijn M. L. , Kosten C. W.
Published: September 2005

A review will be given of the most interesting results of an extensive research program carried out under the auspices of the Organization T.N.O. in the Netherlands since 1945 with the objective to evaluate the insulation of sound in dwellings. The properties of a limited number of constructions were investigated by a subjective inquiry in 1200 flats in Rotterdam and The Hague. Following the preliminary international code for measuring the airborne and impact sound insulation between rooms a rather great number of floor and wall types have been studied in a set of 48 experimental flats in Rotterdam. Some typical results will be given. A new method for estimating the amount of flanking transmission has been found and will be described. A tentative Netherlands standard for sound insulation in dwellings will be sketched in outline. It is based on a classification of walls and floors as to their “over-all” capability of insulating sound. Future research will be concentrated among other things on statistically measuring sound spectra prevailing in dwellings. An automatically recording analyzer is being built for that purpose.
Transmission Loss of Walls in Studios
Authors: Kuhl Walter
Published: September 2005

Measurements are reported for the transmission loss of single, double, and threefold light and heavy partition walls in a large number of radio studios. With different kinds of insulation against structure-borne sound, an average value of transmission loss up to 83 db has been achieved.