bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anomalous origin of one pulmonary artery from the ascending aorta
Authors: Vida Vladimiro L. , Sanders Stephen P. , Bottio Tomaso , Maschietto Nicola , Rubino Maurizio , Milanesi Ornella , Stellin Giovanni 
Published: April 2005

We describe the surgical repair in three infants presenting with one pulmonary artery arising from the ascending aorta, the other artery arising normally from the right ventricle via the pulmonary trunk. Repair consisted of reimplantation of the anomalous pulmonary artery to the pulmonary trunk, in association with repair of associated intracardiac malformations. All patients survived the surgical procedures, and were discharged in stable clinical condition. Subsequently, two of the three patients developed stenosis at the surgical anastomosis relatively early after the initial procedure, and underwent reoperation. Although survival after operation is now expected for this malformation, reports of late results are lacking. Larger numbers of operations are needed before we can reach definitive conclusions.The origin of one branch pulmonary artery from the ascending aorta in the presence of a pulmonary valve and main pulmonary artery is a very rare congenital cardiac anomaly.Patients and methods:Between January 1995 and June 2003, 3 infant girls presented with the origin of one branch artery from the ascending aorta, while the other pulmonary artery originated from the pulmonary trunk which was in continuity with the right ventricular outflow tract. The pulmonary artery that arose from the right ventricle was left in 2 and right in 1 patient.Results:At the age 13, 48 and 62 days respectively, the patients underwent surgical repair consisting with reimplantation of the anomalous pulmonary artery branch to the pulmonary trunk in association with repair of intracardiac malformations. There were no hospital deaths. Postoperative complications included: prologed intubation in two patients (10 and 16 days), low output syndrome in 1 patient, cardiac tamponade in 1 patient and seizures in 1 patient. All patients were discharged in good clinical condition. There have been no late deaths. Subsequently, two of the three patients developed stenosis at the surgical anastomosis relatively early after the initial procedure, and after unsuccessuful balloon dilation, underwent surgical reoperation.Conclusions:Although operative survival is now possible for this malformation, reports of late results are lacking. Two of the three patients developed stenosis at the surgical anastomosis relatively early after surgery. Larger numbers of operations are necessaries to reach definitive conclusions.
Abnormalities in cardiac baroreceptor sensitivity in acute ischaemic stroke patients are related to aortic stiffness
Authors: EVESON David J. , ROBINSON Thompson G. , SHAH Nainal S. , PANERAI Ronney B. , PAUL Sanjoy K. , POTTER John F. 
Published: April 2005

Cardiac BRS (baroreceptor reflex sensitivity) is impaired following ischaemic stroke and predicts the risk of subsequent long-term death and disability. Impaired cardiac BRS may be due to impaired central processing of baroreceptor information following stroke or reduced baroreceptor activity due to increased large artery stiffness. We evaluated the relationship between large (aortic) artery stiffness and cardiac BRS during the acute phase of ischaemic stroke and in comparison with a group of stroke-free control subjects. Thirty-one ischaemic stroke patients were studied within 48 h of onset and again on day 14, along with 26 control subjects free of cerebrovascular disease. Cardiac BRS (determined by spectral analyses) and arterial stiffness estimated by PWVcf (carotid–femoral pulse wave velocity) using applanation tonometry were obtained. At baseline, cardiac BRS was lower in the stroke compared with the control group (4.3±2.3 compared with 6.5±4.2 ms/mmHg; P&lt;0.05). Cardiac BRS values were correlated with PWVcf at &lt;48 h (r=−0.51, P&lt;0.01) and on day 14 (r=−0.54, P&lt;0.01), but not in the control group (r=−0.27, P=not significant). In quantile regression models, taking into account the effect of all cardiovascular variables, cardiac BRS was independently related to PWVcf at baseline and on day 14 in the stroke patients, but stroke was not related to cardiac BRS level when other cardiovascular variables were considered. Wall stiffness of the arterial vessels involved in the baroreflex arc may account for, at least in part, the reduced cardiac BRS observed in acute stroke patients.
Folic acid treatment increases homocysteine remethylation and methionine transmethylation in healthy subjects
Authors: STAM Frank , SMULDERS Yvo M. , van GULDENER Coen , JAKOBS Cornelis , STEHOUWER Coen D. A. , de MEER Kees 
Published: April 2005

Folic acid treatment decreases plasma total homocysteine concentrations in healthy subjects, but the effects on homocysteine metabolism are unknown. In the present study, we investigated the effect of 3 weeks of oral treatment with 5 mg of folic acid on one-carbon flux rates in 12 healthy subjects, using in vivo stable isotope methods. In addition, we determined the effect of folic acid on blood concentrations of amino acids which may have regulatory roles in homocysteine metabolism, i.e. homocysteine, AdoMet (S-adenosylmethionine), AdoHcy (S-adenosylhomocysteine), serine and glycine. Primed, continuous infusions with [2H3-methyl-1-13C]methionine were used to determine flux rates of methionine transmethylation, homocysteine remethylation and homocysteine trans-sulphuration. Metabolic homocysteine clearance was defined as the ratio of trans-sulphuration and plasma homocysteine level. Folic acid treatment increased the homocysteine remethylation rate by 59% [95% CI (confidence interval), 13–97%; P=0.02] and methionine transmethylation rate by 20% (95% CI, 3–41%; P=0.03). Plasma total homocysteine concentration (−18%; 95% CI, −28 to −9%; P&lt;0.01) and the serine/glycine ratio (−20%; 95% CI, −63 to −6%; P&lt;0.01) decreased significantly, and the AdoMet/AdoHcy ratio (11%; 95% CI, 1–20%; P=0.02) increased significantly. Changes in one-carbon flux rates did not correlate significantly with changes in plasma concentration of these amino acids. In conclusion, folic acid treatment lowered plasma homocysteine concentration and increased whole-body remethylation and transmethylation flux in healthy subjects.
Effective Stress and Effective Strain in Relation to Stress Theories of Plasticity
Authors: White G. N. , Drucker D. C. 
Published: April 2005

The correlation of experimental data and the proper description of the state and history of deformation of work-hardening materials has received much attention. An often desired objective is the plotting of a variable involving stress alone, a so-called effective stress, against a variable depending on the instantaneous strain or the history of strain, effective strain. Quantities such as maximum or octahedral shearing stress and strain or better an integrated effective strain increment have been employed. Also, simple effective stress definitions have been given for anisotropic as well as isotropic metals by Dorn, by Jackson, Smith, Lankford, and by previous investigators.
It is shown that the stress-strain relations of a recent theory of plasticity provide a very convenient means of defining and studying effective stress and effective strain. The strong theoretical and practical limitations of such concepts are indicated and the calculation of specific plastic work is discussed for both isotropic and anisotropic metals.
One of the major objectives of the paper is to stimulate critical experimental examination of as yet unproved assumptions in the theory of plasticity and in the correlation of experimental data.
Determination of Residual Stresses of Quenching Origin in Solid and Concentric Hollow Cylinders from Interferometric Observations
Authors: Sáenz A. W. 
Published: April 2005

A theoretical procedure for the determination of the stresses of quenching origin in solid and concentric hollow cylinders has been derived. The method relies on interferometric data and the assumptions discussed in Section I, whose validity for the technically important case of glass is supported by a number of experimental investigations.
The results should be of interest for the analysis of stresses in quenched glass cylinders, so great in magnitude that the usual cutting techniques are precluded, because of the explosive characteristics of highly stressed objects of this material.
On the Endurance Limit of a Round Bar with Longitudinal Grooves
Authors: Ōkubo H. 
Published: April 2005

In a previous paper, we reached a consideration that the endurance limit of a material should be determined by the amount of the mean stress in a certain area around a point, instead of the stress at the point, and the extent of the area is determined for several kind of metals, by using the results of tension-compression fatigue tests.
In this paper, the extent of area where the mean value of stress to be taken, is determined for a mild steel in another way, viz., by a torsion fatigue test, and we reached the conclusion that the extent of area chiefly depends on the kind of metal and independent of the course of the experiment.
Effect of Coating Composition of Oxide-Coated Cathodes on Electron Emission
Authors: Widell E. G. , Hellar R. A. 
Published: April 2005

Investigation of oxide-coated cathodes has been made to determine the effect on electron emission of varying the proportions of emitting oxides. The results show that maximum electron emission under saturation conditions is obtained from a solid solution containing strontium oxide (SrO) and barium oxide (BaO) in an approximate molecular ratio of 7 to 3.
These results also indicate that maximum size of the co-precipitated alkaline-earth carbonate particle occurs at the same molecular ratio as that giving maximum electron emission from the oxides.
When the saturation emission obtained with a square-wave voltage pulse was measured, the current pulse as observed on a synchroscope was also a square wave and showed no measurable decay characteristic for a pulse duration time of 10 microseconds.
Hypersonic Research Facilities at the Ames Aeronautical Laboratory
Authors: Stevens Victor I. 
Published: April 2005

Two wind tunnels recently completed at the Ames Laboratory of the NACA—the 10- by 14-in. supersonic wind tunnel and the supersonic free-flight wind tunnel—are capable of providing test Mach numbers well in excess of 5. Since at this time such facilities are relatively uncommon, this paper is primarily devoted to a description of these wind tunnels and their associated equipment.
The treatment of the 10- by 14-in. supersonic wind tunnel is concerned for the most part with the design and operation of the nozzle and diffuser which provides Mach numbers of 3.5 to about 8. Some mention is also made of the pressure measuring and flow visualization equipment. In the case of the supersonic freeflight wind tunnel high test Mach numbers are obtained by firing models at high speed into an oncoming supersonic air stream. Consequently the main emphasis is placed upon the launching techniques, the available range of test conditions, and the methods of obtaining data.
Gas Evolution in Liquids and Cavitation
Authors: Schweitzer P. H. , Szebehely V. G. 
Published: April 2005

Nine heavy lubricating oils, four light lubricating oils, three aircraft engine fuels, one diesel fuel, and distilled water were tested for their air solubility and for the rate of solution and evolution of air when equilibrium is disturbed. The technique consisted of shaking of a container partly filled with liquid and taking accurate pressure measurements of the air above the liquid. Since air in solution exerts no pressure, the variation of pressure during and after the agitation furnished information on the amount of air that went into or came out of solution and their time rates. The solution was considered to have reached equilibrium when further shaking no longer changed the air content of the liquid.
A wide variation exists in the solubility constants and rates, but the rate of evolution was always found to be proportional to the supersaturation, and the rate of solution to the undersaturation, under otherwise similar conditions. At room temperature the air solubility constant for distilled water is 1.84 percent, for a gasoline approximately 20 percent, and for (light and heavy) lubricating oils approximately 10 percent. The ``half-life'' for evolution on the other hand was 3.86 sec. for distilled water, 0.13–0.24 sec. for gasoline, 3.6–7.6 sec. for light, and 11.6–51.4 sec. for heavy lubricating oils.
The investigation gave some insight into the phenomenon of cavitation which is still largely shrouded in mystery.
Techniques for Measuring the Dynamic Characteristics of a Low Pressure Discharge
Authors: Barnes Bentley T. , Eros Stephen 
Published: April 2005

The dynamic characteristics of a discharge can be determined by making square-wave changes of arc current. This is done by putting the discharge tube in the plate circuit of a group of pentodes connected in parallel and supplied with a square-wave signal superimposed on a d.c. bias.
Probes operated at constant current are very useful in recording the characteristics of a modulated discharge. For measuring electron temperature (Te), two identical probes are centered about points having the same space potential. If the probes are operated at different fixed currents on the straight line part of the probe characteristic, the voltage between them is proportional to Te. Longitudinal voltage gradient or radial potential differences may be recorded by use of identical probes operated at the same current.
A probe operated at a suitable current will follow roughly the variations in space potential of the adjacent region of the discharge. Another probe made sufficiently negative with respect to such a probe will collect only positive ions. A probe made 0–10 volts positive with respect to the constant-current one gives records from which electron concentrations can be computed. In this case, a bias connection without current flow is obtained by use of a cathode-follower with two stages of direct-coupled amplification.
The oscillograph amplifier used for dynamic probe records must be either a differential one or one with ungrounded power supply. In the latter case, the stray capacitance is many times larger; but fairly reliable records can be obtained if the arc current is 0.1 ampere or more, and if the time constant for the decay of the transient effects being measured is at least 10 microseconds. The oscilloscope amplifier and any preamplifier used for recording spectral intensities should be direct-coupled.
Precision Determination of the Lattice Constants of Zinc Oxide
Authors: Heller R. B. , McGannon J. , Weber A. H. 
Published: April 2005

A total of 350 back-reflection ZnO powder x-ray diffraction lines on 25 photographic films have been measured and analysed by the Cohen analytical least squares extrapolation method to yield a=(3.2495±0.00002)A, c=(5.2069±0.00011)A; where the stated errors are the probable errors. The statistical reliability of the results is emphasized.
In the measurement of the Debye-Scherrer ring radii the accuracy obtained with a metric scale and indicator (employing no optical lens system) and with a dividing engine equipped with a microscope are compared and the former simpler method is found more reliable. It is concluded that the use of precision measuring instruments for observing diffraction ring radii are unnecessary and even undesirable apparently because the magnifying power of the optical system of precision micrometers leads to uncertainties in settings on photographic lines.
Depolymerization by Ultrasonic Irradiation: The Role of Cavitation
Authors: Weissler Alfred 
Published: April 2005

Contrary to current belief, cavitation has been found responsible for the depolymerizing effect of intense ultrasonic waves. This was demonstrated by irradiating two portions of a 1 percent polystyrene solution in toluene under conditions identical except for the following. The first portion was given no special prior treatment, showed many cavitation bubbles during irradiation, and decreased in molecular weight (as measured by the intrinsic viscosity) to about one-tenth of the initial value. The second portion was given a preliminary treatment of degassing by boiling under vacuum, showed no cavitation bubbles during the irradiation, and underwent no appreciable change in molecular weight.
Similar experiments with solutions of hydroxyethyl cellulose in water showed that, in this case also, cavitation is necessary for depolymerization. The opposite conclusion of earlier investigators is attributed to their inadequate method for eliminating cavitation.
Oxidants known to be produced by ultrasonic waves in solutions containing dissolved oxygen or nitrogen cannot be responsible for the degradation, because substantially the same amount of depolymerization occurs even when helium is the only gas present.
An Optical Method for Measuring the Stress in Glass Bulbs
Authors: Read W. T. 
Published: April 2005

In the sealing and processing of electron tubes residual stresses are introduced into the glass parts. This paper formulates a practical optical method for locating and measuring the maximum tension in the walls of glass bulbs.
The basic principles of photoelasticity in three dimensions are applied to the case of a cylindrical shell. Theoretical results are verified experimentally for a tube in which the stress distribution is axially symmetrical.
Experimental results on tubes in which the stress distribution was unsymmetrical lead to the conclusion that the maximum tensile stress is proportional to the maximum retardation, the factor of proportionality being simply related to the form of the fringe pattern.
A quick and simple technique is described for making the necessary optical measurements.
The method presented herein has been used and found to be practical for routine laboratory testing of tubes in quantity.
Mechanical Properties of Oriented Polystyrene Film
Authors: Nielsen Lawrence E. , Buchdahl Rolf 
Published: April 2005

Cast films of polystyrene were oriented by stretching at temperatures above the softening temperature of the material and then cooled. A factorially designed experiment was carried out in which the amount of stretching, temperature of stretching, time held in the stretched state before cooling, and effect of several cycles of stretching before cooling were investigated as they affect the birefringence, the stress-strain properties, dynamic modulus and damping, and the softening temperature of polystyrene.
The values of many of the mechanical properties are more closely related to the birefringence than to the amount of hot stretching. In general, the value of the stress-strain properties in the direction of hot stretch, the dynamic modulus, and the birefringence all increase with an increase in the amount of stretching, a decrease in temperature, an increase in rate of cooling after stretching, and a decrease in the number of times the film was stretched before finally cooling. The softening temperature is decreased in direct proportion to the birefringence. Annealed films give higher softening temperatures than films which have been stretched and then allowed to shrink before cooling.
Light Energy and Spectral Distribution for Some Important X-Ray Screens
Authors: Sköldborn Holger 
Published: April 2005

The absolute energy of the light (ergs/cm2 per r-unit) and its spectral distribution have been determined for four different types of x-ray fluorescent screens: Patterson E-2, Patterson B-2, Patterson D, and Neossal. The investigation was performed in accordance with an objective spectrophotometric process with the aid of a tungsten ribbon filament lamp as a standard, a light attenuator of reflection type, monochromator, multiplier photo-tube, and galvanometer.
The application of the method employed to the weak light intensities in question is made possible on account of the enormous light sensitivity of the multiplier photo-tube and the possibility of reproducible continuous variation of this sensitivity within very wide limits. The method has proved speedy and accurate and appears to be well suited for investigations of similar character, within the spectral range which may be measured by the commercial types of multiplier photo-tubes.
A Quantized Theory of Strain Hardening as Applied to the Cutting of Metals
Authors: Shaw Milton C. 
Published: April 2005

A theory of strain hardening is presented which utilizes the fact that metals deform blockwise rather than continuously. A metal is assumed to possess an orderly array of weak spots through which slip planes pass. The slip displacement which occurs upon a single plane is related to the spacing of weak points and the slip plane inclination. Use of a linear relation between shear plane displacement and resisting shear stress, enables the mean shear stress to be computed.
In the two examples considered it is seen that the influence of normal stress on the shear plane is less important in cutting than has been generally believed. Strain hardening and the short range inhomogeneity of metals is seen to account for most of the dynamic increase in shear strength during cutting, including the increase in shear energy per unit volume with decreased depth of cut. This size effect is akin to the increase in tensile strength with decreased specimen diameter, both phenomena involving strain hardening as influenced by inhomogeneity. The quantity Aa2 which represents in a single number the strain hardening and short range inhomogeneity characteristics of a metal should prove particularly valuable in analyzing the cutting characteristics of metals which strain harden extensively.
Stress Analysis for Compressible Viscoelastic Materials
Authors: Read W. T. 
Published: April 2005

Mathematical methods of stress analysis are presented for linear, compressible, viscoelastic, or anelastic, materials such as metals at high temperatures or high polymers with small strains. For such materials stress, strain and their time derivatives of all orders are related by linear equations with coefficients which are material constants. Fourier integral methods are used to show that static elasticity solutions can be used to determine the time dependent stresses in viscoelastic bodies with any form of boundary conditions.
If stress and double refraction and their time derivatives are also linearly related, the standard photoelastic techniques can be used to determine the directions and difference in magnitude of the time dependent principal stresses, even though the principal stress axes do not coincide with the polarizing axes and both vary with time. When viscoelastic models are used in photoelastic studies, the time variation of the stress distribution in the model represents a first approximation to the dependence of the stress in the elastic prototype on Poisson's ratio.
Transonic Potential Flow of a Compressible Fluid
Authors: Sears W. R. 
Published: April 2005

Even under the assumptions of irrotational, isentropic flow, which have been found generally useful for subsonic and supersonic cases, the equations of gas flow are relatively intractable for mixed, transonic situations. Approximate methods of solution used by a number of investigators are reviewed briefly, as well as the hodograph technique, which yields exact solutions of the equations for plane flow. It is pointed out that all the methods predict smooth, potential mixed flows involving imbedded regions of supersonic speed and both acceleration and deceleration through the speed of sound. There is no experimental verification of the existence of such flows.
Three possible explanations for this sharp discrepancy between experiment and perfect-fluid theory have been advanced; namely, (a) effects of viscosity, (b) non-existence of neighboring solutions, and (c) temporal instability. These are reviewed in turn. None has led to a complete explanation, to date. Kuo's stability calculations are described briefly. His results indicate that stable, smooth, mixed flows may exist if certain conditions are satisfied.