bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-dimensional analyses related to wave-energy extraction by submerged resonant ducts
Authors: Lighthill James 
Published: April 2006

Submerged resonant ducts offer an approach to the design of wave-energy extraction devices consistent with the need for maximum seaworthiness. This paper gives a full account of one type of analysis of these systems, based upon two-dimensional wave hydrodynamics and linearized duct dynamics. The mathematical analyses are given in detail in § 2 while § 1 describes as concisely as possible (i) the assumptions underlying each analysis, (ii) its results and their implications for design, and (iii) any available experimental comparisons.One theoretical prediction, unexpected when it was first made but since confirmed by experiment (Knott & Flower 1979), is that the effective pressure fluctuations to which a resonant duct responds can be substantially greater than those that would be present at the level of the duct mouth if the duct were absent. Other important predictions are concerned with added mass, radiation damping and the conditions for optimum energy extraction, calculated below for a wide variety of mouth design configurations and internal duct geometries. Broad tentative conclusions from the analyses are given at the end of § 1.
The relative diffusion of a cloud of passive contaminant in incompressible turbulent flow
Authors: Chatwin P. C. , Sullivan Paul J. 
Published: April 2006

A problem of major practical interest is the variation with x and t of the statistical properties of Γ(x, t), the distribution of concentration of a contaminant in a cloud containing a finite quantity Q of contaminant, released in a specified way at t = 0 over a volume of order L30. Of particular relevance is the case of relative diffusion (when x is measured throughout each realization relative to the centre of mass of the cloud), when important properties are L(t), the linear dimension of the cloud, C(x, t), the ensemble mean concentration, $\overline{c^2}({\bf x}, t)$, the variance of the concentration, and p(y, t), the distance-neighbour function. Much fundamental work has led to a knowledge of the way L varies with t, but not of the way the other properties vary. Hitherto therefore, prediction of such variation has normally used unjustifiable empirical concepts such as eddy diffusivities, but this is ultimately unsatisfactory, practically as well as theoretically. Hence the exact equations have been used to obtain a quite new description of the structure of a dispersing cloud, which it is hoped will serve as a basis for future practical work.When κ = 0 (where κ is the molecular diffusivity) the magnitude of p(y, t) is of order Q/L3 for most y, but of order Q/L30 when |y| is very small. By a variety of arguments it is shown that these facts can be explained (for many, if not all, flows) only if the distributions of C and $\overline{c^2}$, as well as that of p, have a core-bulk structure. In the bulk of the cloud C and $\overline{c^2}$ have magnitudes of order Q/L3 and Q2/L30L3 respectively, but there is a core region of thickness decreasing to zero surrounding the centre of mass within which they have much greater magnitudes. In one case, examined in some detail, the magnitudes in the core are of order Q/L30 and Q2/L60.It is then shown that the core and bulk exist even in the real case when κ ≠ 0. In the real case the core thickness no longer tends to zero but to a constant of order λc, the conduction cut-off length. As a consequence almost entirely of molecular diffusion acting in the core region, the magnitudes of C and $\overline{c^2}$ in both the core and the bulk decay to zero in a way which depends on the details of the fine-scale structure of the velocity field. Several examples of the decay are discussed.
The hydrodynamics of flagellar propulsion: helical waves
Authors: Higdon J. J. L. 
Published: April 2006

The swimming of a micro-organism by the propagation of helical waves on a long slender flagellum is analysed. The model developed by Higdon (1979) is used to study the motion of an organism with a spherical cell body (radius A) propelled by a cylindrical flagellum (radius a, length L).The average swimming speed and power consumption are calculated for helical waves (amplitude α, wavenumber k). A wide range of parameter values is considered to determine the optimal swimming motion. The optimal helical wave has ak ≈ 1, corresponding to a pitch angle of 45°. The optimum number of waves on the flagellum increases as the flagellar length L/A increases, such that the optimum wavelength decreases as L/A increases. The efficiency is relatively insensitive to the flagellar radius a/A. The optimum flagellar length is L/A ≈ 10.The results are compared to calculations using two different forms of resistance coefficients. Gray-Hancock coefficients overestimate the swimming speed by approximately 20% and underestimate the power consumption by 50%. The coefficients suggested by Lighthill (1976) overestimate the swimming speed for large cell bodies (L/A < 15) by 20% and underestimate for small cell bodies (L/A > 15) by 10%. The Lighthill coefficients underestimate the power consumption up to 50% for L/A < 10, and overestimate up to 25% for L/A > 10. Overall, the Lighthill coefficients are superior to the Gray-Hancock coefficients in modelling swimming by helical waves.
Conditional sampling study of the turbulent wake of a cylinder. Part 1
Authors: Fabris Gracio 
Published: April 2006

The far turbulent wake of a slightly heated cylinder was studied using our specially developed four-wire probe and digital processing of signals obtained. The processing method included a simultaneous solution of full nonlinear response equations for the four sensors yielding values of instantaneous velocity vector and temperature. The accuracy of results was improved substantially by the subtraction of free-stream velocity and temperature variations, first-order corrections for the d.c. drift of the signals, the elimination of 60 Hz related noise, and instantaneous correction for the streamwise displacement between the sensor wires. A low temperature threshold was used to discriminate between turbulent and potential flow.The frequency of crossing of the turbulent-potential interface and statistics of turbulent and potential zone intervals are presented. Conditionally sampled fluctuating velocity and temperature fields are given for turbulent and potential zones as well as for a fluid at the downstream and upstream interface of the turbulent zones. Averaging was done with respect to conventional (Reynolds) as well as local zone or point means. The results on turbulence structure up to second-order correlations are presented in this paper.It is hoped that the data will be useful for those interested in methods of prediction of turbulence, especially those based on the consideration of large structures. Researchers more interested in the physical phenomena involved might also find the data suitable for further analysis and interpretation.
The diffraction of a planar detonation wave at an abrupt area change
Authors: Edwards D. H. , Thomas G. O. , Nettleton M. A. 
Published: April 2006

Previous experimental work on the diffraction of a detonation wave at a large and abrupt area change in a tube, has shown that every system is characterized by a critical tube diameter at which quenching of the detonation occurs. Zeldovich, Kogarko & Simonov (1956) established that the critical tube diameter, for the oxy-acetylene system with varying dilution of nitrogen, lies between 500 and 700 times the one-dimensional induction zone length. Later, Mitrovanov & Soloukhin (1964) discovered that, for the same system, the critical diameter is 10 or 13 times the transverse wave spacing for a flat channel and cylindrical tube respectively. The two results are shown to be equivalent and are confirmed by further experiments in a 75 × 6 mm channel in which the flow is two-dimensional.Smoked foil and schlieren records show that, for supercritical waves, re-ignition occurs at sites along the wedge formed by the head of the expansion from the diffracting aperture and criticality is attained when the site is located at the apex of the wedge. A universal feature of re-initiation, which is also observed in liquid and solid explosives, is the sudden appearance of a transverse detonation which sweeps through the compressed, but unreacted, gas of the dissociated shock-reaction zone regime; this is signalled by the appearance of fine triple-point writing on smoked-foil records.A criterion for re-initiation is formulated by equating the critical velocity gradient which characterizes the decay of the wavefront in a cell, to that obtaining in the diffracted shock front at the head of the expansion fan; an expression for the latter is derived from Whitham's (1957) theory for non-reactive shocks. The prediction of the criterion is in good agreement with observation.
The unsteady pressure field of a ducted impeller
Authors: Dang Dac Q. , Norrie D. H. 
Published: April 2006

Analyses based on a three-dimensional vortex-filament model are presented for the unsteady pressure field generated by a ducted propeller. An oscillating part is identified in the kernels and absolute terms of the governing equations for the harmonic components, allowing two methods to be developed for the solution of the higher harmonics. The first method is exact and is applicable to ducted propellers with practical configurations (small chord-to-diameter ratio) while the second is approximate but more suitable for ducted systems with large chord-to-diameter ratios. The second method was applied to a configuration for which experimental data were available and good agreement was obtained for pressure harmonic amplitudes downstream of the propeller and for phase angles upstream of the propeller.Special consideration was given to the Kutta-Joukowski condition at the duct trailing edge and a general constraint developed for the doubly coupled governing integral equations.
On the flow around a buoyant cylinder within a rapidly rotating horizontal cylindrical container
Authors: Gans Roger F. 
Published: April 2006

Steady flow in a cylinder of finite length rotating rapidly at right angles to the earth's gravity and containing a rigid cylindrical float is found under the assumption of small viscosity. The float is modelled by a ‘rigid free surface'. The major new result is a prediction of the rotation rate of the interface, which differs by a factor of O(E1/4) from those given by Greenspan (1976) and Wood (1977) for a rigid interface in an infinitely long cylinder. The difference is accounted for by the appearance of Stewartson layers on the inner boundary in the finite case. The result is supported by an experiment of my own, and is not in conflict with the experimental results given by Greenspan.Some additional experimental observations are reported: a comparison of free and rigid surface rotation rates; and a brief description of the spin-up from rest.
Thermally-induced extrudate swell
Authors: Phuoc H. B. , Tanner R. I. 
Published: April 2006

In many polymer processing applications, the generation of heat by viscous losses in the flowing molten polymer is highly significant. The heating reduces the viscosity of the melt sharply and the flow patterns are different from the isothermal case. In this paper, a finite element scheme based on the Galerkin method is developed and is used to explore the effects of thermally induced property changes in extrusion.In the program we solve simultaneously for the flow and temperature fields at each iteration. To check the program for accuracy and correctness, some simple problems were first attempted. A solution for viscous heating in Poiseuille flow was used to check the variable-viscosity part of the program. The crucial convection (‘radiation’) boundary condition was checked using the solution for cooling of a moving rod. Finally, the swelling of extruded jets with self-heating was investigated. A new phenomenon, thermal extrudate swell, was thereby discovered. We have found extrudate expansions up to 70% of the die diameter in a Newtonian fluid with thermal properties similar to those of low density polyethylene. It is clear that this phenomenon will affect many experimental interpretations of extrudate swelling.
Successful steroid treatment of acquired idiopathic partial hypohidrosis
Authors: YORITAKA Asako , HISHIMA Tsunekazu , AKAGI Kumiko , KISHIDA Shuji 
Published: April 2006

ABSTRACTThe pathogenesis of idiopathic‐acquired hypohidrosis remains unknown, and no specific causes have yet been established. We report a 34‐year‐old man with acquired idiopathic hypohidrosis successfully treated with prednisolone. The patient noticed heat intolerance and hypohidrosis of the pectoral and back during the summer. No systemic disease or neurological findings were identified. Eccrine sweat glands displayed infiltration by inflammatory cells, with immunoglobulin G and C3 deposition in the basement membrane. Steroid therapy improved the hypohidrosis. An immunological pathogenesis could be a major factor in idiopathic‐acquired hypohidrosis.
Pigmented coalescing papules on the dorsa of the hands: Pigmented colloid milium associated with exogenous ochronosis
Authors: GÖNÜL Müzeyyen , ÇAKMAK Seray Külcü , KILIÇ Arzu , GÜL Ülker , HEPER Aylin Okçu 
Published: April 2006

ABSTRACTColloid milium is a rare cutaneous deposition disorder that frequently occurs in areas of chronic sun exposure such as the face, neck and backs of the hands and is characterized by multiple small, discrete, usually amber‐colored, dome‐shaped papules that cluster to form large plaques. A 50‐year‐old white woman with esophageal squamous cell carcinoma was referred to us with asymptomatic, slowly spreading lesions localized to the dorsa of her hands which had been present for 4 years. The condition was diagnosed histopathologically as pigmented colloid milium associated with exogenous ochronosis (EO). Colloid milium associated with EO is very rarely reported in the published work. We think that a possible interaction between sunlight and exposure to chemical fertilizers may have played a role in the pathogenesis of both of the disorders in our case.
Effects of Mycophenolic Acid on Inosine Monophosphate Dehydrogenase I and II mRNA Expression in White Blood Cells and Various Tissues in Sheep
Authors: Dzidic A. , Prgomet C. , Mohr A. , Meyer K. , Bauer J. , Meyer H. H. D. , Pfaffl M. W. 
Published: April 2006

SummaryMycophenolic acid (MPA) is a mycotoxin commonly found as Penicillium genus secondary metabolite in feedstuffs and silages. Feeding with MPA contaminated silages may modulate the immune system in the farm animals and can cause appetite lost, ketosis, paralysis and abortion. The aim of the present study was to characterize the long‐term MPA effect on both the inosine monophosphate dehydrogenase (IMPDH) isoforms I and II mRNA expression in white blood cells (WBC) and various tissue of healthy sheep. In treated animals 300 mg MPA/day/sheep was applied. In all investigated tissues the IMPDH I and II mRNA was abundant: WBC, spleen, thymus, ileum, jejunum, kidney, liver, pharyngeal and mesenterial lymph node. An efficiency‐corrected relative quantification of the IMPDH types I and II isoforms mRNA were performed by normalizing with the constant reference gene expression of β‐actin. High IMPDH I mRNA expression levels were seen in kidney > mesenterial lymph node > jejunum > spleen > pharyngeal lymph node. Medium and low abundance was found in ileum > WBC > liver > thymus. Type II mRNA was highly expressed in liver > thymus > jejunum. In pharyngeal lymph node > spleen > ileum > mesenterial lymph node > kidney > WBC medium to low IMPDH II mRNA concentrations were detected. Under MPA treatment the IMPDH I mRNA expression was not significantly regulated in WBC, only trends of down‐ and upregulation were observed. Surprisingly in jejunum an upregulation could be observed (P < 0.05). In pharyngeal lymph node a tendency to downregulation was shown. This may be due to frequent ruminant activities and frequent exposition of MPA to the pharyngeal lymph nodes. In contrast to type I mRNA expression, IMPDH II mRNA was significantly downregulated in ileum (3.4‐fold, P < 0.01) and tendencies in downregulation could be seen in jejunum (5.1‐fold, P = 0.14). In addition, significant downregulation of IMPDH II gene expression over the entire feeding experiment could be shown in WBC of MPA‐treated animals compared with untreated animals (P < 0.05). In conclusion, the recent study demonstrates that feeding sheep with MPA‐contaminated silage did not induce IMPDH I mRNA expression in various tissues and blood, except in jejunum, but has suppressive effects on IMPDH II mRNA expression in WBC and ileum.
Ophthalmoscopic Characteristics in Sheep and Goats: Comparative Study
Authors: Galán A. , Martín‐Suárez E. Ma. , Molleda J. Ma. 
Published: April 2006

SummaryThe ocular fundus was examined in 40 goat eyes and 40 sheep eyes by studying ophthalmoscopic characteristics and retinograms. Similarities and differing characteristics were described. In common: tapetal colour; peripheral yellowish area surrounding the Winslow stars; unpigmented areas in the non‐tapetal zone; a great amount of myelin in the optic disc; the Bergmeister's papilla and the holoangiotic retinal vascular pattern. Differences: big size of the Winslow stars in goats; myelinizated fibre over the non‐tapetal zone in sheep; shape, position and myelin distribution of the optic disc; and the presence of a ‘primary artery’ in goats.
Primary Pulmonary Adenocarcinoma Metastatic to the Uvea, Brain and Adrenal Gland in a Dog
Authors: Castellano M. C. , Massone A. R. , Idiart J. R. 
Published: April 2006

SummaryA 10‐year‐old male Briard dog was presented because of listlessness, abnormal gait, fever, inappetence, and seizures. A non‐pigmented growth was observed in the ventral quadrant of the left iris. Thoracic radiographs revealed multiple pulmonary metastases and the owner opted for killing. On necropsy, lung masses and nodules in left iris, right adrenal medulla, and brain were detected. Histologically the primary tumour was diagnosed as pulmonary adenocarcinoma with predominant solid pattern. Metastases to regional lymph nodes, uvea, adrenal medulla, and brain were recognized. The metastatic behaviour resembled that occurring in humans. To the authors’ knowledge, this is the first report of a pulmonary adenocarcinoma with metastasis to the uvea in a dog.
Primary Haemangiopericytoma in the Pelvic Cavity of a Dog
Authors: Cho H. S. , Park N. Y. 
Published: April 2006

SummaryA 9‐year‐old female Yorkshire terrier with lameness of the hind leg was examined at the local animal hospital in Gwangju, Republic of Korea on March, 2004. The radiological findings revealed a mass between the urinary bladder and cervix of the uterus. The encapsulated pelvic mass, measuring 4.0 × 3.0 × 2.5 cm was surgically removed. Grossly, the mass was white and firm and microscopically showed a perivascular whorled pattern of spindle cells. By immunohistochemistry, tumour cells tested positive for vimentin and α‐smooth muscle actin, and negative for desmin, S‐100, lysozyme and cytokeratin. The tumour was diagnosed both histologically and immunohistochemically as a haemangiopericytoma. There were no signs of recurrence within 12 months after surgery. This is the first case report of a haemangiopericytoma in the pelvic cavity of a dog.
National survey of spirometer ownership and usage in general practice in Australia
Authors: JOHNS David P. , BURTON Deborah , WALTERS Julia A.E. , WOOD‐BAKER Richard 
Published: April 2006

Objectives and background:  Despite the lack of data, it is believed that spirometry is underutilized in general practice. The aim of the present study was to determine the availability of spirometry and the level of spirometry training in general practice throughout Australia and compare with international data.Methods:  In total, 5976 general practices throughout Australia were sent a questionnaire requesting details of spirometer ownership, usage and the level and source of spirometry training. To exclude response bias, a follow‐up telephone survey was conducted of 160 practices that did not respond to the initial survey.Results:  Of practices 19.5% (1125) responded to the initial survey with 64.2% (722) of these owning a spirometer and 83.9% in the follow‐up sample. Common reasons for not owning a spirometer were equipment cost (53.3%) and insufficient remuneration (32.8%). Most practices (67.0%) performed one or more tests per week. Practices commonly used spirometry to diagnose (89.5%) and manage (93.9%) asthma, assess breathlessness (83.4%) and to detect and manage other diseases such as COPD (77.7%). Spirometer accuracy was never checked using a syringe 77.8% of practices and 40% did not test a healthy subject as part of their quality assurance programme. Spirometry training was received most commonly through courses run by general practice organizations (38.2%), and the duration of training courses was <2 h in 40% of cases.Conclusion:  Despite high spirometer ownership in general practice, the frequency of use is low. Low rates of verification of spirometer accuracy and performance suggest the need for reliable, stable spirometers to be available to general practitioners. Regular and more comprehensive training in spirometry is needed.
Fractional exhaled nitric oxide concentration is increased in asbestosis and pleural plaques
Authors: SANDRINI Alessandra , JOHNSON Anthony R. , THOMAS Paul S. , YATES Deborah H. 
Published: April 2006

Objective and background:  Asbestos exposure induces generation of reactive oxygen and nitrogen species. Nitric oxide is involved in asbestos‐related lung toxicity in vitro and can be measured non‐invasively in humans in exhaled breath. The authors hypothesized that fractional exhaled nitric oxide concentration (FENO) would be increased in subjects with asbestos‐related lung disorders.Methods:  FENO was measured in 56 subjects with asbestos‐related disorders (asbestosis: 12; pleural plaques: 32; asbestos‐related diffuse pleural thickening: 12) and in 35 normal subjects. The authors also measured exhaled carbon monoxide, another marker of lung inflammation.Results:  Median (25–75 percentile) FENO was increased in subjects with asbestosis (7.9 (6.6–15.7) p.p.b.; P = 0.001) and pleural plaques (6.3 (5.3–9) p.p.b.; P = 0.03) compared with normal controls (4.6 (3.5–6) p.p.b.) ). Subjects with DPT had a median FENO of 5.6 p.p.b., similar to controls. No significant differences in exhaled carbon monoxide were observed between controls (1.0 ± 0.3 p.p.m.) and subjects with asbestosis (1.3 ± 0.3 p.p.m.), pleural plaques (1.2 ± 0.3 p.p.m.) or diffuse pleural thickening (1.1 ± 0.3 p.p.m.).Conclusions:  FENO is raised in asbestosis consistent with lung inflammation, and also in pleural plaques.
Marked discordance for myopia in female monozygotic twins
Authors: Dirani Mohamed , Chamberlain Matthew , Garoufalis Pam , Chen Christine , Guymer Robyn H , Baird Paul N 
Published: April 2006

AbstractFemale monozygotic twins aged 54 years discordant for myopia are reported. One twin presented with bilateral high myopia (right eye = −6.00/+0.50 × 5°, left eye = −6.00/+0.50 × 45°) and her identical twin had no significant refractive error (right eye = −0.50/plano, left eye = −0.50/+0.75 × 40°). An explanation for the striking refractive discordance seen in this case report is yet to be determined.