bluuebunny/crossref_metadata_2025_split huggingface dataset:
Airway dimensions in bronchopulmonary dysplasia: Implications for airflow obstruction
Authors: Tiddens Harm A.W.M. , Hofhuis Ward , Casotti Valeria , Hop Wim C. , Hulsmann Anthon R. , de Jongste Johan C. 
Published: November 2008

AbstractThe cause of lung function abnormalities in bronchopulmonary dysplasia (BPD) is incompletely understood, even in the “new era” of this disease. Altered airway wall dimensions are important in the pathogenesis of airflow obstruction in diseases such as asthma and chronic obstructive pulmonary disease. Whether airway wall dimensions contribute to lung function abnormalities in BPD is unknown. The purpose of this study was to investigate airway wall dimensions in relation to airway size in BPD. Lung tissue of patients with BPD was obtained at autopsy, and lung tissue from children who died from sudden infant death syndrome (SIDS) served as control. Airway wall dimensions and epithelial loss were measured in 75 airways from 5 BPD patients and 176 airways from 11 SIDS patients. Repeated measures analysis of variance was used to assess the relationships between airway wall dimensions and airway size for BPD and SIDS patients. Little epithelial loss was present in the BPD patients while extensive loss was observed in some of the SIDS patients. The inner wall area, outer wall area, epithelium area and smooth muscle area were all substantially larger (all P < 0.001) in BPD than in SIDS patients. It is likely that the increased thickness of the airway wall components contributes to airflow obstruction in BPD patients. Pediatr. Pulmonol. 2008; 43:1206–1213. © 2008 Wiley‐Liss, Inc.
Asymmetric Communication in Bilingual Exchanges
Authors: Heredia de Christine 
Published: November 2008

This paper analyzes the characteristics of exolinguistic communication, a type of asymmetric communication. The data base contains five dialogues between French speakers and Latin American Spanish speakers. The subjects did not have any knowledge of French before their arrival in France. The recording situations were as authentic and varied as possible.In exolinguistic communication two speakers actively work together with varying degrees of cooperation and complementary strategies to achieve mutual understanding. In this study we examine the role of repetition, simplification, and facilitation (breaking up information, paraphrases, types of questions which warn of difficulties, etc.) and analyze the characteristics of asymmetric exchanges made up of three- or four-turn sequences which allow speakers to check understanding and avoid misunderstanding.This leads to several hypotheses on natural second language acquisition and, more specifically, on the “guidance” offered by the native speaker and on the role of metalinguistic activities.
Problems in Examining the Validity of the ACTFL Oral Proficiency Interview
Authors: Bachman Lyle F. 
Published: November 2008

The primary problems in measuring speaking ability through an oral interview procedure are not those related to efficiency or reliability, but rather those associated with examining the validity of the interview ratings as measures of ability in speaking and of the uses that are made of such ratings. In order to examine all aspects of validity, the abilities measured must be clearly distinguished from the elicitation procedures, in both the design of the interview and in the interpretation of ratings.Research from applied linguistics and language testing is consistent with the position that language proficiency consists of several distinct but related abilities. Research from language testing also indicates that the methods used to measure language ability have an important effect on test performance. Two frameworks—one of communicative language ability and the other of test method facets—are proposed as a basis for distinguishing abilities from elicitation procedures and for informing a program of empirical research and development.The validity of the ACTFL Oral Proficiency Interview (OPI) as it is currently designed and used cannot be adequately examined, much less demonstrated, because it confounds abilities with elicitation procedures in its design, and it provides only a single rating, which has no basis in either theory or research. As test developer, ACTFL has yet to fully discharge its responsibility for providing sufficient evidence of validity to support uses that are made of OPI ratings.
Comersions and 1-connectedness
Authors: Flaherty F. J. 
Published: November 2008

AbstractA generalization of the notion of Riemannian submersion is given for submersions of a Lorentzian manifold onto a Riemannian manifold of one lower dimension. These maps are called comersions. A comersion induces a surjection of the space of causal curves in the domain manifold onto curves of bounded length in the image manifold. Thus if the source space is causally 1-connected, the target space is 1-connected.
On a problem of moments
Authors: Verblunsky S. 
Published: November 2008

1. The problem in question is to find a necessary and sufficient condition which numbers co, …, cm must satisfy in order that there shall be a non-decreasing function σ(t) such thatwhere (a, b) is an unbounded interval. (When (a, b) is a bounded interval, the problem has been solved. See Achyèser and Krein, Communications de la Société Mathématique de Kharkoff, Série 4, 12 (1935), 13–35, Satz C.)
A note on inequivalence of realizability toposes
Authors: Johnstone P. T. , Robinson E. P. 
Published: November 2008

The general construction of realizability toposes was first described in [3]. The data from which such a topos is constructed (called a partial applicative structure in [3]) consists of a set A equipped with a partial binary operation (called application and denoted by juxtaposition, with the convention that unbracketed expressions are evaluated from left to right) and two constants K, S satisfyingfor all x, y, z ∈ A (where, as usual, an equality between possibly undefined terms means ‘one side is defined iff the other is, and then they are equal’). Following Lambek [6], we now call such a structure a partial Schönfinkel algebra, or a global Schönfinkel algebra if application is defined on the whole of A × A. (The name ‘combinatory algebra’ is also in common use.) We write for the realizability topos constructed from A.
A Green's function for diffraction by a rational wedge
Authors: Rawlins A. D. 
Published: November 2008

AbstractIn this paper we derive an expression for the point source Green's function for the reduced wave equation, valid in an angular sector whose angle is equal to a rational multiple of π. This Green's function can be used to find new expressions for the field produced by the diffraction of a spherical wave by a wedge whose angle can be expressed as a rational multiple of π. The expressions obtained will be in the form of source terms and real integrals representing the diffracted field. The general result obtained is used to derive a new representation for the solution of the problem of diffraction by a mixed hard–soft half plane.
On Coulomb wave functions
Authors: Meligy A. S. , El Gazzy E. M. 
Published: November 2008

AbstractThe irregular radial Coulomb wave function in repulsive fields is expressed, for any angular momentum value, in series of Bessel functions of arbitrary order. Previous expansions, obtained for angular momenta zero and one, can now be obtained as special cases. The expansion can be most conveniently used for high-energy particles.
Further results for the solutions of a third-order differential equation
Authors: Ezeilo J. O. C. 
Published: November 2008

1. The equation considered here is of the formwhere a, b are constants, h(x) is differentiable and h′(x), p(t) are continuous in x, t respectively. The primary object of the paper is to prove the followingTheorem 1. Suppose that(i) a > 0,b > 0;(ii) h(0) = 0, h(x)/x ≥ δ > 0 (x ≠ 0);(iii) h′(x) ≤ c for all x where ab > c > 0.
Structures on M × R
Authors: Browder William 
Published: November 2008

A central role in the theory of smoothing combinatorial manifolds is played by the Cairns–Hirsch Theorem, which may be expressed (in a weak form) as follows:If M is a combinatorial manifold and if M × R has a differentiable structure a, compatible with its combinatorial structure then M has a differentiable structure λ, such that (M × R)α is diffeomorphic with Mλ × R.
On the probability of artificial nuclear transformations and its connection with the vector model of the nucleus
Authors: Goldhaber M. 
Published: November 2008

1. The theorem of quantum mechanics that “the spin part of the angular momentum is approximately a constant of motion provided that the forces depending on the direction of the spins are small compared with the total interaction forces” is introduced into the discussion of artificial nuclear transformations. A definition is given for the terms “probable” and “not probable” nuclear reaction.2. Attention is drawn to the experimental result that the reaction Li6 + H1 → He4 + He3 is more probable than the reaction Li7 + H1 → 2He4, and an explanation is suggested.3. The nuclear spin of Lie is derived from nuclear transformations and found to be 1.4. Similar derivations for the spins of H3, He3 and B11 are summarised in a table.
A theorem of Dr P. Zeeman
Authors: Grace J. H. 
Published: November 2008

The following theorem, first enunciated by Dr Zeeman in 1899, has attracted the attention of several writers:If five points A, B, C, D, E in three dimensions are such that the feet of the perpendiculars from E on the faces of the tetrahedron ABCD are coplanar the relation between the five points is symmetrical.
The triode oscillation generator and amplifier: limitations on sinoidal performance
Authors: Turner L. B. , Meacham L. A. 
Published: November 2008

The characteristic relationship subsisting between anode current ia, anode potential ea, and grid potential eg in a well-evacuated thermionic triode, viz.leads to very simple analysis of the circuit conditions when μ, is a constant and φ is a linear function. In all the usual applications of triodes, μ is very nearly a constant; in some applications, e.g. in good acoustic amplifiers, over the working range φ is very nearly linear; in others, e.g. in rectifiers, non-linearity is essential to the performance. In oscillators, and in power amplifiers used with them, both conditions are met. Where a sinoidal oscillation is desired, i.e. an alternating current as devoid of harmonics of the fundamental frequency as can be contrived, the working range must be sensibly linear. A feature of such a régime is that the major portion of the power supplied to the triode must be dissipated in heating the anode. Where higher efficiency is required, the cycle must be made to extend beyond the linear range, and harmonics are necessarily introduced.
On the calculation of the energy in unsaturated hydrocarbon molecules
Authors: Coulson C. A. 
Published: November 2008

It frequently happens that we wish to evaluate the total energy of the mobile, or π, electrons in an unsaturated hydrocarbon molecule. According to the method of molecular orbitals(1) this energy is the sum of individual electronic energies ∊r, and the summation is over all the occupied orbitals. The energies ∊r are the roots of the secular determinant, and, if we writeand suppose that there are n unsaturated carbon atoms, then the equation that gives the energies zr is
The Mobility Distribution and Rate of Formation of Negative Ions in Air
Authors: Hamshere J. L. 
Published: November 2008

A modification of the alternating field method of measuring ionic mobility in a gas gives an experimental curve showing upper and lower limits to k. From this a distribution curve is derived, which has a calculable resolving power.The mobility of negative ions in dry air shows a continuous distribution between the limits 2·15 and 1·45, with a peak value about 1·8.At low pressures the current is resolved into ions and free electrons. From the relative numbers reaching the electrometer it is found that the electron makes an average number 9·4. 104 collisions before capture, independent of field strength and pressure, and therefore independent of the electron speed over a range W = 2×105 to W = 7×105.
A Maximum-Minimum Method of Determining the Cardinal Points of a Lens System
Authors: Searle G. F. C. 
Published: November 2008

The method of determining the focal length f of a thin converging lens by finding the minimum distance Δ0 between image and object is well known. When the thickness of the lens is negligible, f = ¼Δ0.In the general coaxial system, the media at the two ends have refractive indices μ1, μ2, and there is a finite distance t between the principal or unite plances. The two focal lengths are unequal, since, f1/f2=μ1/μ2, and the nodal points do not coincide with the principal points.
The theory of the shot effect. II
Authors: Rowland E. N. 
Published: November 2008

Summary of the previous paperThe previous paper dealt first with the shot effect without secondary emission. We considered a stream of electrons arriving at random, with a fixed probable density N, at the anode of the resistance-capacity coupled first valve of a linear amplifier. This does not allow for the effect whereby the arrival of electrons alters the anode potential, and consequently the probability of arrival of succeeding electrons. The valve must be working with what is conventionally called an infinite internal resistance, and without space-charge effects. Each electron arriving at time tr is supposed to produce at time t an output effect f(t − tr) from the amplifier. We considered the hypotheses, first, that electrons may, with specific probabilities, have lives of any length on the anode system, during which they add − ε/C to the anode potential, and alternatively that each electron adds to the anode potential of the valve whose anode to earth capacity is C and whose feed resistance is R. These hypotheses determine the form of f(t − tr) when the behaviour of the main part of the amplifier is known. Since the amplifier is linear, the effects of various electrons are additive, so that the total output is ∂(t) = ∑rf(t − tr).
On the velocity and temperature distributions in the turbulent wake behind a heated body of revolution
Authors: Goldstein S. 
Published: November 2008

Thevelocity distributionin the wake behind a body of revolution calculated by Miss Swain on the momentum transfer theory withlconstant over a cross-section of the wake is not in accordance with experiment.On the generalized vorticity transfer theory the equation for the first approximation to the velocity defectufar downstream isThere are two methods of simplifying this equation on the analogy of the successful simplification of the corresponding equation for the two-dimensional case. One method gives the same equation as if the turbulence were symmetrical; the other gives the equation of the modified vorticity transfer theory.For the former there is no real solution iflis constant over a cross-section; for a real solutionlmust be infinite on the axis of symmetry. The equation was integrated withl∝r−1over a cross-section; this variation oflwas suggested by putting the change in the area enclosed by a circular vortex-line proportional to the area of the section of the wake. The agreement with experiment is fairly good over the middle portion of the wake, but not near the edge, where the theoretical value of ∂u/∂ris not zero. Ifl2∝rp, ∂u/∂rvanishes at the edge of the wake only ifp= − 3. The solution is carried through for this case; it shows only fair agreement with experiment over the middle of the wake, and none at the edge.The calculation on the modified vorticity transfer theory is carried out withlconstant over a section; in this case there is no definite edge to the wake, nor doesufall off sufficiently rapidly to make the momentum integral for the drag converge. (u∝r−2for larger.) Even over the middle of the wake there is a discrepancy with experimental results, rather like that shown by the momentum transfer theory.Thetemperature distributionbehind a heated body was calculated according to each of the foregoing theories.The temperature distribution was also calculated from the experimental velocity distribution, without any assumption being made concerning the kinematic coefficient of turbulent diffusion, which was eliminated between the equations for the velocity and temperature. The vorticity transfer theory with symmetrical turbulence gives an impossible result. The modified vorticity transfer theory gives θ/θmax<u/umaxwhen the experimental velocity distribution is used.
A further note on Ramanujan's arithmetical function τ(n)
Authors: Hardy G. H. 
Published: November 2008

This note is a sequel to two in earlier volumes of the Proceedings, the first by myself and the second by Wilton†.Suppose thatfor |z| <1; that x > 0; thatforr ≥ 0; and thatwhere τ(x) is to mean 0 if x is not an integer. Thuswhere the dash shows that the last term is to be halved when x is an integer;forr > 1; and
Concerning secondary flow in straight pipes
Authors: Howarth L. 
Published: November 2008

In this paper the condition for the existence of a secondary flow in a straight non-circular pipe is determined according to the modified vorticity transfer theory, with Goldstein's assumed form for the tensorIt is shown that a secondary motion arises if the mixture length is not constant on the curves along which | gradu| is constant,ubeing the velocity parallel to the pipe axis.In problems of turbulent flow treated by means of the modified vorticity transfer theory, the quantitywhereis the mean value of the square of the velocity fluctuation andpthe mean pressure, plays a part analogous to the pressure in laminar flow. In two-dimensional flow through a channel the theory shows the existence of a gradient ofacross the channel from the central plane to each wall. Qualitative arguments such as are used to explain the existence of a secondary flow for laminar motion in a curved pipe are applied here to show that a secondary flow is to be expected near the short sides in the turbulent flow through a straight rectangular pipe of large length/breadth ratio.The equations to determine the secondary flow through an almost circular elliptic pipe are discussed, the mixture length being assumed constant on ellipses similar to and concentric with the pipe section. For a first approximation the problem is reduced to the numerical solution of three simultaneous ordinary linear differential equations.
Corrigendum
Authors: Gillis J. 
Published: November 2008

Note on a Theorem of Myrberg*On p. 421, line 30, of that note I remark “δ(x) is a lower semi-continuous function of x”. That statement is, in general, untrue. The proof should rather run as follows:The subset of E1 where δ(x) ≥ a > 0 is clearly closed and, as α tends to 0, tends to h−mE1. Hence, by taking α sufficiently small, we find a closed subset of E1, of positive h-measure, every point x of which has the property thatwhenever 0 < d ≤ α. We may call this subset again E1 and the proof, from the top of p. 422, goes as before.
A theory of the performance of radar on ship targets
Authors: Wilkes M. V. , Ramsay J. A. 
Published: November 2008

The paper contains a theoretical discussion of the scattering by a ship of the wave sent out from a radar transmitter. An expression is derived for the power returned to the receiver of the radar installation, on the assumption that the ship is composed of a large number of scattering elements which scatter energy non-coherently. Calculations based on this expression are compared with the results of experiment and shown to be in good agreement as regards the variation of signal strength with range, provided that a suitable value for the effective radius of the earth (a quantity which changes with meteorological conditions) is taken.An experiment is described in which the absolute level of the received signal from a ship was measured by comparing it with that from a metalized sphere flown from a balloon. The result was found to be in satisfactory agreement with theoretical expectations.
A note on positive harmonic functions
Authors: Verblunsky S. 
Published: November 2008

If H(ξ, η) is a harmonic function which is defined and positive in η > 0, then there is a non-negative number D and a bounded non-decreasing function G(x) such that(For a proof, see Loomis and Widder, Duke Math. J. 9 (1942), 643–5.) If we writewhere λ > 1, then the equationdefines a harmonic function h which is positive in υ > 0. Hence there is a non-negative number d and a bounded non-decreasing function g(x) such thatThe problem of finding the connexion between the functions G(x) and g(x) has been mentioned by Loomis (Trans. American Math. Soc. 53 (1943), 239–50, 244).
On discrete harmonic functions
Authors: Heilbronn H. A. 
Published: November 2008

A function f(x1, x2) of two real variables x1, x2 which are restricted to rational integers will be called discrete harmonic (d.h.) if it satisfies the difference equationThis equation can be considered as the direct analogue either of the differential equationor of the integral equationin the notation normally employed to harmonic functions.
Some physical interpretations of potentials representing supersonic motion of compressible fluids
Authors: Tempest R. K. 
Published: November 2008

1. Compressible and incompressible flow. Small perturbations in an otherwise uniform stream of compressible fluid moving at supersonic speed are described by the approximate linearized equation for the velocity potential. When the stream flows in the z-direction, the equation assumes the formwhere M is the Mach number of the flow and α2 is positive. In cylindrical polar coordinates (r, z), the equation may be written aswhich is Laplace's equation in coordinates (iαr, z). We may therefore relate potentials of incompressible flow which are solutions of (1·2) to potentials of compressible flow which are solutions of (1·1).
On the asymptotic behaviour of the solutions of a class of non-linear differential equations
Authors: Friedlander F. G. 
Published: November 2008

1. This paper is concerned with certain asymptotic properties of the solutions of the differential equationwhere dots indicate differentiation with respect to t, k is a small parameter, and f(x, ẋ, t) satisfies certain conditions which will be formulated below. Equations of this type occur frequently in non-linear mechanics; for k = 0 a system satisfying (1·1) behaves as a harmonic oscillator. To ensure the existence and uniqueness of the solutions of (1·1) it must be assumed that the right-hand side is bounded and satisfies a Lipschitz condition, at least for finite x, ẋ and say all t ≥ 0. The parameter k may be considered as a measure of the ‘smallness’ of the upper bound, and of the Lipschitz constant, of the right-hand side, and need not have any intrinsic physical significance.
On some new types of partitions associated with generalized ferrers graphs
Authors: Auluck F. C. 
Published: November 2008

1. In this paper we find generating functions and asymptotic expressions for the number of partitions of a positive integer n into two sets of positive integers satisfying the conditionsThe set ‘b’ can be empty. Such partitions are considered by Temperley (1) in a forth-coming paper on the roughness of crystal surfaces. We shall consider them in more detail and under different sets of conditions on the a's and b's.
Periodic solutions of non-linear differential equations of the second order. IV
Authors: Obi Chike 
Published: November 2008

1.1. This paper is a theoretical investigation in the real domain of the existence of subharmonic solutions of non-linear differential equations of the formwhere F is analytic and of least period 2π/ω in t; ε = (ε1, …, εn) is small; and F(x, ẋ, 0, t) is not linear in x and ẋ.