bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonparametric comparison of two survival functions with dependent censoring via nonparametric multiple imputation
Authors: Hsu Chiu‐Hsieh , Taylor Jeremy M. G. 
Published: November 2008

AbstractWhen the event time of interest depends on the censoring time, conventional two‐sample test methods, such as the log‐rank and Wilcoxon tests, can produce an invalid test result. We extend our previous work on estimation using auxiliary variables to adjust for dependent censoring via multiple imputation, to the comparison of two survival distributions. To conduct the imputation, we use two working models to define a set of similar observations called the imputing risk set. One model is for the event times and the other for the censoring times. Based on the imputing risk set, a nonparametric multiple imputation method, Kaplan–Meier imputation, is used to impute a future event or censoring time for each censored observation. After imputation, the conventional nonparametric two‐sample tests can be easily implemented on the augmented data sets. Simulation studies show that the sizes of the log‐rank and Wilcoxon tests constructed on the imputed data sets are comparable to the nominal level and the powers are much higher compared with the tests based on the unimputed data in the presence of dependent censoring if either one of the two working models is correctly specified. The method is illustrated using AIDS clinical trial data comparing ZDV and placebo, in which CD4 count is the time‐dependent auxiliary variable. Copyright © 2008 John Wiley & Sons, Ltd.
The Racketeer Menace and Antiunionism in the Mid-Twentieth Century US
Authors: Witwer David 
Published: November 2008

AbstractIn the postwar era, conservatives manipulated concerns about union corruption and organized crime in order to score political points against New Deal Democrats and to win new legal restrictions on union power. The resulting racketeer menace had much in common with the contemporary red scare. Antiunion conservatives framed the issue of labor racketeering in terms that resembled the language then being mobilized against internal communist espionage and subversion. This rhetoric proliferated in the congressional debates of the postwar era. Proponents of the Taft-Hartley Act invoked the racketeer menace in 1946 and 1947. They depicted the law as an effort to curb racketeering and thus protect workers and the general public by restricting abusive union power. In the years that followed, a series of congressional hearings into union corruption kept attention focused on the issue of racketeering. For the Eisenhower Administration this campaign against labor racketeering offered a chance to peel the working-class vote away from the Democratic Party by politically dividing union members from their leadership. The culmination of this trend came at the end of the 1950s during the McClellan Committee hearings, which was the largest congressional investigation up to that time. Those hearings transformed Teamsters President James R. Hoffa into a potent symbol of the danger posed by labor racketeering. The committee's revelations and the publicity they received undercut the labor movement. Polls showed growing public skepticism toward unions, and especially union leaders. Such attitudes helped conservatives win a new round of legislative restrictions on organized labor in the form of the Landrum-Griffin Act (1959).
Nitrogen availability is not affected by frequent fire in a South African savanna
Authors: Coetsee Corli , February Edmund C. , Bond William J. 
Published: November 2008

Abstract:There is a perception that sustained frequent fires cause nitrogen limitation over the long term (50–100 y) by volatilizing the nitrogen in soil, plant biomass and litter. Here we test this perception in a South African savanna located in the Kruger National Park. At our study site we compare the effects of 50 y of fire exclusion, season (August and February) and frequency (triennial and annual August and triennial February) of burn on nitrogen cycling and availability. We do this using three different methods to determine nitrogen mineralization; in situ incubations, laboratory incubations and ion-exchange resin bags. On each treatment we established two parallel transects 100 m apart with 10 sampling points per treatment along these transects. Daily mineralization rates for in situ incubations were determined monthly from August 2004 to June 2005 at each of the sampling points. Ion-exchange resin bags were buried (5 cm) at the same points and left in the field from August 2004 to August 2005. In February 2005 five randomly located soil samples from each of the four treatments were collected for laboratory incubations using a 7-cm-diameter soil auger. Regardless of method used our results show that there are no significant differences in daily nitrogen mineralization rates after 50 y of different burning treatments from annual burning to fire exclusion. In fact, both in situ and laboratory incubations show that nitrogen availability is higher on the annual burn than the fire exclusion (0.16 μg g−1soil d−1vs. 0.11 μg g−1soil d−1and 0.46 μg g−1soil d−1vs. 0.30 μg g−1soil d−1respectively). Perceived negative effects of fire on ecosystem functioning has curbed the use of fire as a management tool with fire often actively suppressed in savanna. The results of our study show that fire can be used more vigorously in mesic African savanna to manipulate tree:grass ratios without negatively affecting the nitrogen cycle.
Too Many Words: Length of Utterance and Pragmatic Failure
Authors: Blum-Kulka Shoshana , Olshtain Elite 
Published: November 2008

This paper investigates the theoretical and applied domains of pragmatic failure. With respect to theory, it further clarifies pragmatic failure both in native and non-native speech, and with respect to the applied domain compares request realizations of native and non-native speakers in terms of length of utterance. In discussing the results of this comparison, a number of hypotheses are put forward concerning the ways in which deviation from native norms of utterance length might be a potential cause for pragmatic failure.The data were collected within the CCSARP (Cross-Cultural Speech Act Realization Pattern) project involving seven different languages and dialects (Blum-Kulka & Olshtain, 1984). The data were collected from both native and non-native speakers of each of the languages. The analysis of responses across several languages revealed a systematic difference in length of utterance used to realize speech acts by non-native speakers as compared to native speakers. The types of pragmatic failure that might be linked to being a non-native speaker are examined, thus continuing a line of research focusing on the pragmatic aspects of interlanguage (Blum-Kulka, 1982; Thomas, 1983; Edmondson et al., 1984).
Constructing an Acquisition-Based Procedure for Second Language Assessment
Authors: Pienemann Manfred , Johnston Malcolm , Brindley Geoff 
Published: November 2008

This article reports on a first attempt to develop and test run an observation procedure for assessing the syntactic and morphological development of adult learners of English as a second language (ESL) as evidenced in spontaneous speech production. The procedure is based on the profile analysis approach, which was first developed by Crystal, Fletcher, and Gorman (1976) for the assessment of impaired speech (English) and later adapted to the assessment of second language development (German) by Clahsen (1985). The theoretical basis of the procedure is the multidimensional model of second language acquisition (SLA) developed by Meisel, Clahsen, and Pienemann (1981) and extended to ESL acquisition by Pienemann and Johnston (1987a). According to the model, invariant developmental stages in the acquisition of certain syntactic and morphological elements in German and English can be predicted and explained in terms of hierarchically ordered speech processing constraints.In order to assess the developmental stage of ESL learners, an observation form was drawn up, incorporating a selection of morphosyntactic features whose presence or absence in a taped sample of natural speech was monitored by assessors. The ratings made by the assessors were then compared to those assigned through a detailed linguistic analysis to test the feasibility of using a “shorthand” version of a profile analysis.Analysis of the outcomes of the test run revealed significant correlations between the assessments and the linguistic analysis. But some variation was found in the assessors' ability to apply the assessment criteria, and the extent of agreement between the assessors' observations and the linguistic analysis was less than would be acceptable in the given theoretical framework. However, the source of these problems was identified through the first test run and suggestions were made for further refining the procedure to improve its accuracy.
Focus-on-Form and Corrective Feedback in Communicative Language Teaching
Authors: Lightbown Patsy M. , Spada Nina 
Published: November 2008

The developing oral English of approximately 100 second language learners (four intact classes) was examined in this study. The learners were native speakers of French (aged 10–12 years) who had received a 5-month intensive ESL course in either grade 5 or grade 6 in elementary schools in Quebec. A large corpus of classroom observation data was also analyzed.Substantial between-class differences were found in the accuracy with which students used such English structures as progressive -ing and adjective–noun order in noun phrases. There was some evidence that these differences (which were not correlated with performance on listening comprehension tests) were due to differences in teachers' form-focused instruction. These findings are discussed in terms of current competing views of the role of form-focused instruction in second language learning.
The hydrodynamics of non-Newtonian fluids. II
Authors: Rivlin R. S. 
Published: November 2008

In this paper, the general hydrodynamic theory of visco-inelastic, incompressible, non-Newtonian fluids, developed in a previous paper (l), is applied to the problem of the flow of such a fluid through a tube of circular cross-section. It is found that the absolute values of the normal stress components are no longer uniform over a cross-section of the tube normal to its axis, as in the case of Newtonian fluids obeying the laws of classical hydrodynamics.However, the pressure difference, between points at equal radii on two planes normal to the axis, is independent of the position of these points on the planes.
The solution of an infinite set of differential-difference equations occurring in polymerization and queueing problems
Authors: Wragg A. 
Published: November 2008

AbstractThe time-dependent solutions of an infinite set of differential-difference equations arising from queueing theory and models of ‘living’ polymer are expressed in terms of modified Bessel functions. Explicit solutions are available for constant values of a parameter describing the arrival rate or monomer concentration; for time-dependent parameter a formal solution is obtained in terms of a function which satisfies a Volterra type integral equation of the second kind. These results are used as the basis of a numerical method of solving the infinite set of differential equations when the time-dependent parameter itself satisfies a differential equation.
Dissociative Equilibrium in an External Field of Force
Authors: Milne E. A. 
Published: November 2008

(1) The conditions of dissociative equilibrium in an external gravitational field have been given by Willard Gibbs, as follows: If the state of a system is such that it is in (mechanical and thermodynamic) equilibrium when the constituents are taken to be independent, and if a condition of dissociative equilibrium is satisfied at one point, then the same condition is satisfied at all points, and the state is one of equilibrium if the constituents are actually capable of dissociating.(2) In particular, the constituents of a column of dissociating gas under gravity settle out according to Dalton's law; if the condition of dissociative equilibrium is satisfied at one height it is satisfied at all heights.(3) The conditions of equilibrium are generalised so as to take account of external electric fields and of the possibility of the products of dissociation being charged. Result (1) is shown to be unaffected.(4) The theory is applied to the equilibrium of an ionized gas such as a stellar atmosphere under gravity. Whatever the charge on the star, the tendency of the light electrons to diffuse away from the heavy ions is almost entirely prevented by the electrostatic forces between them, and the result is the production of a field in the interior capable of supporting half the weight of the positiveions (Pannekoek, Rosseland). For the purposes of this statement the “interior” may be taken to commence at a pressure of 10−24 atmos. It is only above the level corresponding to 10−34 atmos. that electrons and ions separate out according to Dalton's law.(5) The theory is applied to the equilibrium of an ionized gas under an external electric field. An external applied field of the order of 40,000 volt cm.−1 cannot give rise to potential differences exceeding about 1 volt under the conditions of a typical stellar atmosphere.
An infinite summation formula associated with Appell's function F2
Authors: Srivastava H. M. 
Published: November 2008

1. Recently in these proceedings we proved that, if ℜ(α) > 1 and ℜ(α) > − 1, then ((10), p. 1088)where F2 denotes the Appell function (see, e.g., (8), p. 211),with, as usual,and for covergence of the double series,and x⇌y indicates the presence of a second term that originates from the first by interchanging x and y.
The distribution of second order moment statistics in a normal system
Authors: Wishart J. , Bartlett M. S. 
Published: November 2008

Let x be a normally distributed variable, which may without loss of generality be measured from the mean of the distribution, so that E(x) = 0, E denoting mathematical expectation. Then x satisfies the differential relationwhere k2 (otherwise σ2 or (2h2)−1) is the semi-invariant of order 2. Also k1 = 0, and we know that kr = 0 for r > 2.
On the theory of the recombination of ions in gases at high pressures
Authors: Harper W. R. 
Published: November 2008

Previous theories of the recombination of ions in gases are shown to be inapplicable to high pressures. An approximate quantitative theory which takes into account all the relevant phenomena is developed. The effect of both thermal agitation and mutual attraction in determining encounters of ions of opposite sign is considered, and the frequency of encounters which lead to recombination calculated. The criterion for an encounter to lead to recombination is that the drift of the ions towards each other due to their mutual attraction must be greater than their tendency to separate due to their Brownian movement. Excellent agreement is obtained with such experimental results as are available. Preferential recombination between an ejected electron and its parent ion is also discussed.I am indebted to various members both of the Wills Physics Laboratory and of the Cavendish Laboratory for discussion of the problems dealt with in this paper.
The spectrum of the self-adjoint partial differential equation in any domain
Authors: Steen S. W. P. 
Published: November 2008

The object of this paper is to obtain the general solution to the self-adjoint partial differential equation in n dimensionswhere pij, q and ρ and bounded, continuous functions of (x1,…, xn) in a domain D and on its boundary, and where ∑pijXiXj≥0 for all (x1,…, xn) of D and all X1,…, Xn. The domain D is an n-dimensional domain and may be either the whole or part of a Riemann surface space of n dimensions. Its boundary is to consist of any number, zero, finite or enumerable, of continuous continua of n − 1 dimensions. These terms will be explained in paragraph II. The solution u = u(x1,…, xn; t) will be valid for (x1,…, xn) in D and t ≥ 0, and will satisfy boundary conditions of the type or similar, these conditions becoming identical at any part of the boundary of D that lies at infinity.
On the ambiguity in the specification of a two-sheeted surface by its branch curve
Authors: Du Val P. 
Published: November 2008

It is familiar that a “double plane”, i.e. an algebraic surface conceived as consisting of each point of a plane counted twice, is unambiguously determined when its “branch curve”, or locus of points in the plane which count as two coincident points of the surface (the general point of the plane counting as two distinct points), is assigned; the only condition which must be satisfied by this curve being that it is of even order. In fact, if f(x, y) = 0 is the Cartesian equation of the curve, the double plane can be regarded as the limit of the surfacewhere A is a large constant, or as the projection of this surface, for finite A, from the point at infinity on the z-axis. If, however, f = 0 is of odd order, it is easily seen that the line at infinity also forms part of the branch curve of the double plane. A repeated portion of the branch curve is ineffective, for if φ (x, y) = 0 is any other curve, the surfaceis birationally identical with the former merely by putting
Note on the Formula for the Number of Quadrisecants of a Curve in Space of Three Dimensions
Authors: Maxwell Edwin A. 
Published: November 2008

If pCε is a curve of order ε and genus p without singularities in space of three dimensions, the formula for the number of quadrisecants is well known, namely*,Welchman has shown that the necessary reduction in this formula when the curve pCε has a point of multiplicity r with r distinct tangents, no three of which are coplanar, is
A Statistical Derivation of Langmuir's Adsorption Isotherm
Authors: Fowler R. H. 
Published: November 2008

The commonest form of Langmuir's adsorption isotherm iswhere θ is the fraction of the surface of the solid covered by adsorbed molecules, p the gas pressure in equilibrium with the adsorbed layer and A = A (T) a function of the temperature alone. This formula is usually derived by a kinetic argument which balances the rates of deposition and re-evaporation. It is perhaps not without interest to show that formula (1) and similar formulae can be obtained directly by the usual statistical methods which evaluate all the properties of the equilibrium state of any assembly. The ordinary derivation is apt to obscure the essentially thermodynamic character of (1) and to lead one to think that its form depends on the precise mechanisms of deposition and re-evaporation, whereas in fact it depends only on the whole set of states, adsorbed and free, accessible to the molecules in question. By suitable use of the usual technique for handling assemblies obeying the Fermi-Dirac statistics the saturation effect can be naturally incorporated in the theory ab initio.
Some Experiments with Neutrons slowed down at different Temperatures
Authors: Westcott C. H. , Niewodniczanski H. 
Published: November 2008

Experiments are described comparing the effects of neutrons slowed down in paraffin wax at the temperatures of liquid nitrogen and liquid hydrogen with those obtained at ordinary temperatures. It is found that the absorption produced by certain substances increases as the temperature is lowered. The transformations produced in these substances also increase, but generally to a smaller extent, probably owing to more neutrons being absorbed in the paraffin: the exact figure depends on the thickness of the layer of cooled paraffin.A few experiments were also made substituting liquid hydrogen for paraffin wax (without change of temperature). The effect of this also appears to depend on the thickness of the layer, but it is not yet possible to draw definite conclusions.
On the Obliquity Function to be used in the Approximate Theory of Diffraction
Authors: Harper W. R. 
Published: November 2008

The solution of problems in diffraction by an elementary application of Huyghens's principle is discussed. The obliquity function is investigated, using the criterion that the formula used must give the right result when integrated for the case of an undiffracted plane wave. It is shown that this is satisfied for distant points by any function which makes the integrals converge, but that to satisfy it completely a constant obliquity function is necessary. This makes a consideration of the distant boundary essential, as the integrals do not converge in this case. It is shown that a boundary distributed in a Gaussian way is completely satisfactory. The integral for the case of diffraction by a straight edge is solved exactly, leading to the usual result. Finally, the results are discussed in relation to the teaching of the subject.I am indebted to Dr H. Jeffreys and to Mr F. P. White for their interest in this paper; also to Mr N. F. Mott, who has contributed much to the course of its development.
A System of Linear Equations with an Infinity of Unknowns
Authors: Titchmarsh E. C. 
Published: November 2008

I have collected in the present note some theorems regarding the solution of a certain system of linear equations with an infinity of unknowns. The general form of the equations isthe numbers a1, a2, … c1, c2, … being given. Equations of this type are of course well known; but in studying them it is generally assumed that the series depend for convergence on the convergence-exponent of the sequences involved, e.g. that and are convergent. No assumptions of this kind are made here, and in fact the series need not be absolutely convergent. On the other hand rather special assumptions are made with regard to the monotonic character of the sequences an and cn.
The Enumeration of the Partitions of Multipartite Numbers
Authors: Macmahon P. A. 
Published: November 2008

This paper is a study of a new method of enumeration of the partitions of multipartite numbers.Incidentally an algebraic function, which is derived from the repetitional exponents of partitions of unipartite numbers, presents itself. The generating function which enumerates the partitions of unipartite numbers is expressible in terms of these functions and finds in such expression its fullest connection with the divisors of numbers. There are also similarly derived functions connected directly with bipartite, tripartite, etc. numbers. It has not been necessary to study these for the purposes of this paper.
Poisson's Summation Formula in several Variables and some Applications to the Theory of Numbers
Authors: Mordell L. J. 
Published: November 2008

In a recent paper, Poisson's summation formulawas proved very simply by integration by parts, subject to the conditions:(α) for all real values of x, f(x) and f′(x) are continuous and f (x)→0, f′ (x)→0 as |x| → ∞.(β) f(x) and f″(x) are such that the integrals, converge.