bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased prevalence of gastrointestinal symptoms in patients with allergic disease
Authors: Powell Nick , Huntley Benedict , Beech Thomas , Knight William , Knight Hannah , Corrigan Christopher J 
Published: March 2007

Abstract

Background
Children with allergic diseases such as asthma and atopic dermatitis experience increased gastrointestinal symptoms. Further, physiological and histological abnormalities of the gastrointestinal tract in patients with allergic diseases have been reported. It is not certain whether adult patients experience increased gastrointestinal symptoms.

Methods
A retrospective, case–control study of 7235 adult (⩾20 years old) primary care patients was conducted. A general practitioner diagnosis of irritable bowel syndrome was used to serve as a marker of lower gastrointestinal symptoms. The prevalence of lower gastrointestinal symptoms was calculated in patients with asthma or allergic rhinitis and compared with that in patients with other chronic diseases (insulin-dependent diabetes mellitus, osteoarthritis and rheumatoid arthritis) and with the remaining population.

Results
Gastrointestinal symptoms were significantly more common in patients with asthma (9.9%) as compared with patients with chronic diseases (4.9%; odds ratio (OR) 2.13, 95% confidence interval (CI) 1.39 to 2.56; p&lt;0.002) or the remaining non-asthmatic population (5.5%; OR 1.89, 95% CI 1.39 to 2.56; p&lt;0.001). Gastrointestinal symptoms were also significantly more common in patients with allergic rhinitis (7.9%) as compared with patients with chronic diseases (4.9%; OR 1.66, 95% CI 1.02 to 2.7; p&lt;0.05) and the remaining population (5.5%; OR 1.47, 95% CI 1.04 to 2.1; p&lt;0.02). This phenomenon was independent of age, sex and inhaled asthma therapy in the case of patients with asthma.

Conclusions
Our findings support the hypothesis that lower gastrointestinal symptoms are more common in patients with allergic diseases such as asthma and allergic rhinitis.
Patent foramen ovale and atrial septal aneurysm in cryptogenic stroke
Authors: Ghosh Sujoy , Ghosh Arjun Kumar , Ghosh Sandip Kumar 
Published: March 2007

Abstract
Up to 40% of acute ischaemic strokes in young adults are cryptogenic in nature, that is, no cause is determined. In more than half of these patients, patent foramen ovale (PFO) is seen along with an increased incidence of atrial septal aneurysm. The commonest method of investigation is echocardiography (preferably transoesophageal echocardiography). On the basis of available evidence, low risk patients are treated with antiplatelet agents and high risk patients with warfarin. There are inconclusive data on the efficacy of PFO closure to prevent stroke recurrence. However, if there is recurrent stroke or intolerance to medical therapy, percutaneous closure is carried out.
Simvastatin-induced bilateral leg compartment syndrome and myonecrosis associated with hypothyroidism
Authors: Ramdass Michael J , Singh Gurpreet , Andrews Brian 
Published: March 2007

Abstract
A 54-year-old hypothyroid male taking thyroxine and simvastatin presented with bilateral leg compartment syndrome and myonecrosis. Urgent fasciotomies were performed and the patient made an uneventful recovery with the withdrawal of simvastatin. It is likely that this complication will be seen more often with the increased worldwide use of this drug and its approval for all arteriopathic patients.
Developing your teaching style: increasing effectiveness in healthcare teaching
Authors: Mohanna Kay , Chambers Ruth , Wall David 
Published: March 2007

Abstract
This paper reports the first stage in the development of a tool, the Six Staffordshire Teaching Styles Questionnaire, designed to raise awareness in teachers about their teaching style. Effective teachers are adaptable and flexible in providing variety in their teaching activities, aiming to match their manipulation of the teaching and learning environment to the needs of the learner, but teachers should also know what type of activities they are most effective at delivering. Just as mismatched learning styles can cause dysfunctional learning situations, one of the causes of stress in teachers can be an incongruency between the type of activities they believe are effective, or feel they are good at carrying out, and external expectations of “good teaching”.
Coupled Vibration of Unshrouded Centrifugal CompressorImpellers. Part I: Experimental Investigation
Authors: Hasemann Heinrich , Hagelstein Dirk , Rautenberg Manfred 
Published: March 2007

The increased use of small gas turbines and turbochargers in different technical fields has led to the development of highly‐loaded centrifugal compressors with extremely thin blades. Due to the high rotational speed and the corresponding centrifugal load, the shape of the impeller hub must also be optimized. This has led to a reduction of the thickness of the impeller disc in the outlet region. The thin parts of the impeller are very sensitive and may be damaged by the excitation of dangerous blade vibrations.dangerous blade vibrations. Experimental investigations by means of holographic interferometry and telemetry were carried out for two different impeller types; one with radial‐ending blades and the other with backswept blades. The results presented in Part I of the paper are able to explain the dominance of coupling effects between the blades and the disc in the middle and higher frequency range of the two tested impellers. Especially excitations caused by downstream sources such as vaned diffusers can endanger the blades and the impeller.The finite element (FE) code computations presented in Part II of the paper to investigate the coupled vibration behavior of the whole impeller were found to be in close agreement with the experimental results.
Theoretical and Experimental Investigation of the Dynamic Behaviour of Centrifugal Fans
Authors: Mariaux G. , Gervais Y. , Crespeau L. 
Published: March 2007

In this paper, a theoretical model is proposed to investigate the centrifugal fans′ transient behaviour in response to sudden imposed changes in pressure or flow rate. We are especially interested in the dissipative or creative energy transient behaviour of the fans located in actual aeraulic networks.The model is based on the global modelisation of the motor and resistant torques (due to pressure and viscosity actions on the blades) which are present on the rotor and by their coupling with its inertia.The model is then validated by experimental measurements which show its validity. In the case of the tested fan, the instantaneous characteristics (in particular the flow rate and rotation speed) have been correctly predicted by the model, with regard to time as well as amplitudes, provided the flow is not reversed.
Pump Damage in the Hanshin Earthquake
Authors: Osada Toshiyuki 
Published: March 2007

There was a severe earthquake in the southern area ofHyogo prefecture in Japan on January 17, 1995. In this paper the damage to pump facilities caused by the earthquake, based on field investigation results in the Hanshin (Osaka–Kobe) area is reported. In particular a lot of damage was reported in the pumping facilities for sewage or drainage of storm sewage. This paper also presents recommendations for aseismic design of pump facilities based on the results of the survey.Some of the kinds ofdamage to pumps were: pump submersion, shaft misalignment, case of pump rotor getting stuck, anchor bolt failure, pump casing cracking, bearing box failure. Most of the damage was fundamentally caused by unequal sinking ofthe building foundation. The damage to the pumps was mainly caused by deformation or collapse of building structures, or by excessive forces to be exerted on the pumps by the piping.In order to prevent damage to pumps by earthquakes, a study of the earthquake resistance of the whole pumping facility including the pump itself should be made, and appropriate countermeasures and action taken.
Abnormally High Power Output of Wind Turbine in Cold Weather: A Preliminary Study
Authors: Leclerc Christophe , Masson Christian 
Published: March 2007

According to popular belief, air temperature effects on wind turbine power output are produced solely by air density variations, and power is proportional to air density. However, some cases have been reported, all involving stall‐controlled wind turbines, in which unexpected high power output was observed at very low temperatures.As a preliminary study, this article intends to quantify the influence of air temperature on the power production of the Tacke TW600 wind turbine installed in Tiverton, Ontario, Canada. Increases in power output due to air temperature variation are stratified by wind velocity, showing that these increases are below the theoretical limits of air density variations during operation in low winds and are comparable to and beyond those theoretical limits at higher wind velocities. At – 9°C and 0°C, narrow bands of power at distinct levels are observed in the stall regime of the turbine; they are typical of many stall phenomena observed on stall‐controlled rotors, but these levels have been found to be independent of any parameters recorded.
Investigation of Flow Through Centrifugal Pump Impellers Using Computational Fluid Dynamics
Authors: Zhou Weidong , Zhao Zhimei , Lee T. S. , Winoto S. H. 
Published: March 2007

With the aid of computational fluid dynamics, the complex internal flows in water pump impellers can be well predicted, thus facilitating the design of pumps. This article describes the three‐dimensional simulation of internal flow in three different types of centrifugal pumps (one pump has four straight blades and the other two have six twisted blades). A commercial three‐dimensional Navier‐Stokes code called CFX, with a standard k–ε two‐equation turbulence model was used to simulate the problem under examination. In the calculation, the finite‐volume method and an unstructured grid system were used for the solution procedure of the discretized governing equations for this problem.Comparison of computational results for various types of pumps showed good agreement for the twisted‐blade pumps. However, for the straight‐blade pump, the computational results were somewhat different from widely published experimental results. It was found that the predicted results relating to twisted‐blade pumps were better than those relating to the straight‐blade pump, which suggests that the efficiency of a twisted‐blade pump will be greater than that of a straight‐blade pump. The calculation also predicts reasonable results in both the flow pattern and the pressure distribution.
Vibration and Stability of 3000‐hp, Titanium Chemical Process Blower
Authors: Gutzwiller Les , Corbo Mark A. 
Published: March 2007

This 74‐in‐diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil‐film bearings and was directdriven by a 3000‐hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system.Although the blowers showed very satisfactory vibration levels during test runs at the manufacturer′s plant, the vibration levels in situ had always been higher than was desirable. After several months of monitoring showed ever increasing vibration levels, one of the blowers was shut down in order to diagnose and resolve the problem.Several steps were taken to diagnose the problem: (1) The rotor was removed and the shop balance was checked and corrected. (2) The bearing support movement due to thermal expansion was measured. Then the shafts were misaligned in the cold condition in order to achieve near‐perfect shaft alignment during normal operation. (3) The expected shaft vibration at the bearings was determined using lateral rotor dynamics analysis, including critical speed mapping. (4) A heavy sleeve was added to the blower shaft to increase the radial load on the drive‐end bearing. (5) The metal disk type of coupling was replaced by a gear coupling. (6) The finite element and impact of the bearing support pedestal were tested to determine the stiffness of the bearing support. (7) The shaft movement was measured during a coast‐down. (8)Tilting‐pad bearings were evaluated as a possible replacement for the original standard sleeve type of hydrodynamic oil‐film bearings.The final solution showed the importance of coupling angular stiffness (often rarely considered in machine design), rotor dynamic analysis, and field alignment.
Spatial Dynamics of Tuned and Mistuned Bladed Disks with Cylindrical and Wedge‐Shaped Friction Dampers
Authors: Panning Lars , Sextro Walter , Popp Karl 
Published: March 2007

One of the main tasks in the design of turbomachines like turbines, compressors, and fans is to increase the reliability and efficiency of the arrangement. Failures due to blade cracks are still a problem and have to be minimized with respect to costs and safety aspects. To reduce the maximum stresses, the blades can be coupled via friction damping devices such as underplatform dampers that are pressed onto the blade platforms by centrifugal forces. In this work, a method will be presented to optimize two different types of underplatform dampers in bladed disk applications with respect to a maximum damping effect.In practice, underplatform dampers with various geometric properties—cylindrical and wedge‐shaped—are commonly used and lead to different contact conditions. A discretization of the contact areas between the blade platforms and the dampers is applied to be able to investigate nearly arbitrary contact geometries and spatial blade vibrations. The functionality of the two mentioned damper types has been studied in detail under different working conditions of the assembly. The advantages and disadvantages of both damper types are pointed out and strategies are presented to improve the damper design. In this context, the influence of mistuning effects is discussed in terms of statistical mistuning of the blades′ natural frequencies due to manufacturing tolerances as well as systematical mistuning due to a deliberate slight variation of the blade masses or geometries.
Numerical Calculation of the Three‐Dimensional Swirling Flow Inside the Centrifugal Pump Volutes
Authors: Nursen E. Cezmi , Ayder Erkan 
Published: March 2007

The flow inside the volute of a centrifugal pump is threedimensional and, depending upon the position of the inlet relative to the cross‐section center line, a single or double swirling flow occurs. The purpose of this study was the calculation of the three‐dimensional swirling flow inside the centrifugal pump volute.The developed flow solver provides detailed pressure and velocity distribution information inside the volute, and the calculated results are verified by means of the experimental results presented in the literature.Three‐dimensional continuity and momentum equations are solved by means of an artificial compressibility technique. The finite volume approach is applied for space discretization, and an explicit fourth‐order modified Runge‐Kutta scheme is used for time discretizetion.Calculations are performed at three different mass flows, one of which corresponds to the design′s point mass flow. The calculated volute flow conditions—namely, the variation in static pressure and total pressure and the through‐flow and swirling component of the flow velocity over the cross‐sections, which are located at various circumferential positions—are compared with the experimental data in detail, and they exhibit a good agreement with the measured flow field.
Experimental Investigation of Cavitation Signatures in an Automotive Torque Converter Using a Microwave Telemetry Technique
Authors: Anderson C. L. , Zeng L. , Sweger P. O. , Narain A. , Blough J. R. 
Published: March 2007

A unique experimental investigation of cavitation signatures in an automotive torque converter under stall conditions is reported. A quantitative criterion is proposed for predicting early and advanced cavitation in terms of suitable nondimensional pump speeds. The dimensionless pump speed that marks early cavitation is obtained by relating this parameter to the appearance of charge‐pressure–dependent pressure fluctuations in the differential pressure transducer readings. The differential pressure transducers were mounted at well‐defined locations in the pump passage of a torque converter. The data were transmitted by a wireless telemetry system mounted on the pump housing. Data were received and processed by a ground‐based data acquisition system. Automatic transmission fluid exhibited cavitation for charge pressures of 70–130 psi and pump speeds of 1000– 2250 rpm. Advanced cavitation was marked by operating conditions that exhibited a 2% or more torque degradation from the converter′s noncavitating performance.For a given family of torque‐converter designs and a given transmission fluid, the proposed nondimensional pumpspeed criteria are capable of marking early and advanced stages of cavitation for a range of torque‐converter sizes and a range of charge pressures in the torque converter.
Parametric Study of Greitzer′s Instability Flow Model Through Compressor System Using the Taguchi Method
Authors: Ng Eddie Yin-Kwee , Liu Ningyu , Tan Shin Yi 
Published: March 2007

The occurrence of stall and surge is caused by instability of the flow through the compressor system. These two phenomena often result in serious mechanical problems for the compressor. The scope of this article includes a review and parametric study on the characteristics of stall and surge and their mathematical modeling.In this article, Greitzer′s B‐parameter model is applied for analyzing the stall and surge characteristics. Based on this model, a total of four parameters—B, G, K, and LC—in the model are highlighted in order to establish the influence of each parameter on the system. Parameters B, G, and K are all dimensionless constants while LC is the effective length of the compressor duct.Here, the governing equations of stall and surge behavior are solved numerically using fourth‐order Runge‐Kutta method. The Taguchi method is then used to analyze the results
generated to obtain the extent of effects of the parameters on the system by varying the parameters in a series of combinations. Finally, a thorough analysis is carried out on the results generated from the Taguchi method and the graphs. It is found that parameter K is the deciding factor in the position of the cross point whereas parameter B is the most important one in changing the length of time needed for the compressor to reach its steady state.
Deflections and Strains in Cracked Shafts due to Rotating Loads: A Numerical and Experimental Analysis
Authors: Bachschmid N. , Tanzi E. 
Published: March 2007

In this article, the deflections of a circular cross‐section beam presenting a transverse crack of different depths, due to different loads (bending, torsion, shear, and axial loads), are analyzed with the aid of a rather refined 3‐D model, which takes into account the nonlinear contact forces in the cracked area. The bending and shear loads are applied in several different angular positions, in order to simulate a rotating load on a fixed beam, or, by changing the reference system, a fixed load on a rotating beam. Torsion and axial loads are instead fixed with respect to the beam.Results obtained for the rotating beam can then be used for the analysis of cracked, horizontal axis heavy rotors, in which the torsion is combined to the bending load. The effect
of friction is also considered in the cracked area. The characteristic “breathing” behavior of the cracked area has been analyzed and compared to that one obtained with a rather simple 1‐D model. The differences in results with respect to those which can be obtained by means of the approach based on fracture mechanics are emphasized.In order to highlight the effect of the presence of the crack, the deflections of the uncracked beam loaded with the same loads are subtracted from the deflections of the
cracked beam.Finally, a cracked specimen has been extensively analyzed by means of several strain gauges, for analyzing the strain distribution on the outer surface around the crack, in different loading conditions. Consistent pre‐stresses have been found, which influence the breathing behavior. The experimental results have been compared to those obtained with
the 1‐D linear model.
The Flow Rate Influence on the Interaction of a Radial Pump Impeller and the Diffuser
Authors: Akhras A. , El Hajem M. , Champagne J.-Y. , Morel R. 
Published: March 2007

This article presents the results of a detailed flow investigation within a centrifugal pump equipped with a vaned diffuser. The measurements were made with a laser Doppler velocimeter and were carried out at different operating points. The flow was investigated for different rotor–stator relative positions.Unsteady velocity measurements, obtained in phase with the rotor angular position, gave access to the flow inside the impeller channels where three sections were explored. In the diffuser, five sections were studied. Thus, time resolved details of the flow were examined for a better understanding of the complex unsteady flow existing between the two interacting blade rows.Results obtained at different operating conditions show that the rotor‐stator interaction is affected by the diffuser position and the flow rate.
Adiabatic Effectiveness and Heat Transfer Coefficient of Shaped Film Cooling Holes on a Scaled Guide Vane Pressure Side Model
Authors: Dittmar Jan , Schulz Achmed , Wittig Sigmar 
Published: March 2007

The demand of improved thermal efficiency and high power output of modern gas turbine engines leads to extremely high turbine inlet temperature and pressure ratios. Sophisticated cooling schemes including film cooling are widely used to protect the vanes and blades of the first stages from failure and to achieve high component lifetimes.
In film cooling applications, injection from discrete holes is commonly used to generate a coolant film on the blade′s surface.In the present experimental study, the film cooling performance in terms of the adiabatic film cooling effectiveness and the heat transfer coefficient of two different injection configurations are investigated. Measurements have been made using a single row of fanshaped holes and a double row of cylindrical holes in staggered arrangement. A scaled test model was designed in order to simulate a realistic distribution of Reynolds number and acceleration parameter along the pressure side surface of an actual turbine guide vane. An infrared thermography measurement system is used to determine highly resolved distribution of the models surface temperature. An in-situ calibration procedure is applied using single embedded thermocouples inside the measuring plate in order to acquire accurate local temperature data.All holes are inclined 35° with respect to the model′s surface and are oriented in a streamwise direction with no compound angle applied. During the measurements, the influence of blowing ratio and mainstream turbulence level on the adiabatic film cooling effectiveness and heat transfer coefficient is investigated for both of the injection configurations.