bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectral Analysis of Replicated Biomedical Time Series
Authors: Diggle Peter J. , Al Wasel Ibrahim 
Published: March 2003

SUMMARY
Standard methods of spectral analysis are adapted to the interpretation of biomedical time series data with replication across subjects. The methodology is applied to two sets of data consisting of concentrations of luteinizing hormone in serial blood samples. For such data, the between-subject variability in periodogram ordinates at a given frequency is typically larger than would be implied by the usual asymptotic distribution theory for single series. We interpret this to mean that the underlying spectrum of the stochastic process representing the time variation in hormone concentration varies randomly between subjects. We describe simple random effects models to account for this extra variability and develop likelihood-based methods of inference, using a Monte Carlo integration method to evaluate the likelihood function. For our first data set, which comprises hormone concentrations in blood samples taken from eight subjects at 1 min intervals for 1 h, our model captures the qualitative behaviour of the between-subject variation in the spectrum. We conclude that there is a genuine high frequency component of variation in hormone concentrations and that the amplitude and frequency of this high frequency component vary between subjects. Our second data set relates to a similar sampling protocol, except that each subject is sampled before and after hormone replacement therapy. We conclude that this intervention has a significant effect on the spectrum.
Statistics for Extreme Sea Currents
Authors: Robinson Michael. E. , Tawn Jonathan A. 
Published: March 2003

SUMMARY
Estimates of various characteristics of extreme sea currents, such as speeds and their directions, are required when designing offshore structures. This paper extends standard statistical methods for extreme values to handle the directionality, temporal dependence and tidal non-stationarity that are present in sea current extremes. The methods are applied to a short period of data from the Inner Dowsing Light Tower in the North Sea. Substantial benefits, over existing methods, are obtained from our analysis of the sea current by decomposing it into tide and surge currents. In particular, we find that at the Inner Dowsing the strong directionality in extreme sea current speeds is completely explained by the tidal current and directionality in the non-extreme surge currents. This finding aids model fitting and extrapolation.
A New Look at Half-Normal Plots for Assessing the Significance of Contrasts for Unreplicated Factorials
Authors: Olguín Jorge , Fearn Tom 
Published: March 2003

SUMMARY
The visual inspection of a half-normal plot is a popular procedure for interpreting data from unreplicated factorial experiments. As this technique is somewhat subjective, the plot should preferably be supplemented with a more formal procedure. However, despite the improvements proposed by Zahn, the formal method using the half-normal plot suggested by Daniel seems to be rarely used. We investigate this procedure by using simulations and real data and suggest a modification to improve its acceptability. We also present corrected critical values for a procedure proposed by Lenth which was found to be miscalibrated.
Statistical Inference for the Effect of Magnetic Brain Stimulation on a Motoneurone
Authors: Ventura V. , Davison A. C. , Boniface S. J. 
Published: March 2003

SUMMARY
A stochastic model is developed for the possible excitatory and inhibitory effects of a stimulus to the brain on the activity of single human motoneurones. The model consists of a Wiener process for the build-up of underlying potential, a deterministic effect due to the stimulus and a random lag from brain to muscle. Direct likelihood inference for its parameters seems impossible, and we study the use of simulation to estimate the log-likelihood for the parameters of substantive interest. Monte Carlo methods yield point and confidence interval estimates of the membrane excitability underlying excitatory and inhibitory effects. The main qualitative conclusion is that both excitatory and inhibitory effects are unambiguously present. The contribution of statistical analysis to this problem is to provide accurate and apparently reliable inference for the quantities of neurophysiological interest. More generally, our methodology has the potential to make accurate likelihood-based inferences in challenging problems, but the computational burden can be large, particularly if the model is not fully adequate for the data, as in our application.
Markov Models of Mite Movements
Authors: Ridout Martin S. , Faddy Malcolm J. , Jones Graeme , Campbell Colin A. M. 
Published: March 2003

SUMMARY
Continuous time Markov models were used to analyse data from two bioassays to investigate the influence of β-fraction, a by-product of hop processing, on the two-spotted spider mite. The models were fitted to aggregate counts of the numbers of live and dead mites on treated and untreated halves of discs cut from leaves of hop and French bean plants. Some of the rate parameters were time dependent. Although not all parameters could be estimated precisely, the analysis enabled the quantitative effects of treatment over time to be estimated with reasonable precision. The estimated treatment effects were largely insensitive to the assumed values of other parameters. The first bioassay showed a progressive initial response to increasing concentration of β-fraction, although data at the intermediate concentration appeared anomalous. The second bioassay showed similar responses on hop and French bean leaves, with a stronger repellent effect on the lower leaf surface than on the upper surface.
Spatial Variation in Risk of Disease: A Nonparametric Binary Regression Approach
Authors: Kelsall Julia E. , Diggle Peter J. 
Published: March 2003

SUMMARY
A common problem in environmental epidemiology is the estimation and mapping of spatial variation in disease risk. In this paper we analyse data from the Walsall District Health Authority, UK, concerning the spatial distributions of cancer cases compared with controls sampled from the population register. We formulate the risk estimation problem as a nonparametric binary regression problem and consider two different methods of estimation. The first uses a standard kernel method with a cross-validation criterion for choosing the associated bandwidth parameter. The second uses the framework of the generalized additive model (GAM) which has the advantage that it can allow for additional explanatory variables, but is computationally more demanding. For the Walsall data, we obtain similar results using either the kernel method with controls stratified by age and sex to match the age–sex distribution of the cases or the GAM method with random controls but incorporating age and sex as additional explanatory variables. For cancers of the lung or stomach, the analysis shows highly statistically significant spatial variation in risk. For the less common cancers of the pancreas, the spatial variation in risk is not statistically significant.
Stochastic Modelling of the Invasion Process of Nematodes in Fly Larvae
Authors: Faddy M. J. , Fenlon J. S. 
Published: March 2003

SUMMARY
Stochastic models based on Markov birth processes are constructed to describe the process of invasion of a fly larva by entomopathogenic nematodes. Various forms for the birth (invasion) rates are proposed. These models are then fitted to data sets describing the observed numbers of nematodes that have invaded a fly larva after a fixed period of time. Non-linear birth-rates are required to achieve good fits to these data, with their precise form leading to different patterns of invasion being identified for three populations of nematodes considered. One of these (Nemasys) showed the greatest propensity for invasion. This form of modelling may be useful more generally for analysing data that show variation which is different from that expected from a binomial distribution.
Influence of Human Immunodeficiency Virus Infection on Neurological Impairment: An Analysis of Longitudinal Binary Data with Informative Drop-Out
Authors: Liu Xinhua , Waternaux Christine , Petkova Eva 
Published: March 2003

SUMMARY
A study to investigate the human immunodeficiency virus (HIV) status on the course of neurological impairment, conducted by the HIV Center at Columbia University, followed a cohort of HIV positive and negative gay men for 5 years and assessed the presence or absence of neurological impairment every 6 months. Almost half of the subjects dropped out before the end of the study for reasons that might have been related to the missing neurological data. We propose likelihood-based methods for analysing such binary longitudinal data under informative and non-informative drop-out. A transition model is assumed for the binary response, and several models for the drop-out processes are considered which are functions of the response variable (neurological impairment). The likelihood ratio test is used to compare models with informative and non-informative drop-out mechanisms. Using simulations, we investigate the percentage bias and mean-squared error (MSE) of the parameter estimates in the transition model under various assumptions for the drop-out. We find evidence for informative drop-out in the study, and we illustrate that the bias and MSE for the parameters of the transition model are not directly related to the observed drop-out or missing data rates. The effect of HIV status on the neurological impairment is found to be statistically significant under each of the models considered for the drop-out, although the regression coefficient may be biased in certain cases. The presence and relative magnitude of the bias depend on factors such as the probability of drop-out conditional on the presence of neurological impairment and the prevalence of neurological impairment in the population under study.
Detecting a Changed Segment in DNA Sequences
Authors: Avery Peter J. , Henderson Daniel A. 
Published: March 2003

SUMMARY
Non-coding deoxyribonucleic acid (DNA) can typically be modelled by a sequence of Bernoulli random variables by coding one base, e.g. T, as 1 and other bases as 0. If a segment of a sequence is functionally important, the probability of a 1 will be different in this changed segment from that in the surrounding DNA. It is important to be able to see whether such a segment occurs in a particular DNA sequence and to pin-point it so that a molecular biologist can investigate its possible function. Here we discuss methods for testing the occurrence of such a changed segment and how to estimate the end points of it. Maximum-likelihood-based methods are not very tractable and so a nonparametric method based on the approach of Pettitt has been developed. The problem and its solution are illustrated by a specific DNA example.
A Dynamic Random-Effects Model for Recovery of Skin Barrier Function: Evaluation of the Efficacy of Different Skin Care Products
Authors: Erlandsen Mogens , Halkier-Sørensen Lars 
Published: March 2003

SUMMARY
Apparently, the use of mathematical and statistical models to describe the structure and function of the skin barrier is rather limited. The skin barrier protects the body against uncontrolled loss of water and desiccation, and prevents environmental substances from entering the skin. A simple measure of the barrier function is the transepidermal water loss (TEWL), which is easy to measure. Healthy skin has low TEWL values, whereas various skin diseases result in high TEWL values and eventually in the development of dry skin. The use of skin care products can protect and prevent dry skin. In this study several different trial formulations are compared with respect to their abilities as skin care products. The study is performed as a longitudinal study on mice, where the skin barrier is broken by means of acetone and then treated with one of the formulations. We analysed the data by means of a semimechanistic random-effects model with similarities to pharmacokinetic models. In the model each formulation is characterized by two parameters: one that corresponds to the initial barrier restoration effect and one that corresponds to the elimination rate.
Incomplete Covariates in the Cox Model with Applications to Biological Marker Data
Authors: Leong Traci , Lipsitz Stuart R. , Ibrahim Joseph G. 
Published: March 2003

SUMMARY
A common occurrence in clinical trials with a survival end point is missing covariate data. With ignorably missing covariate data, Lipsitz and Ibrahim proposed a set of estimating equations to estimate the parameters of Cox’s proportional hazards model. They proposed to obtain parameter estimates via a Monte Carlo EM algorithm. We extend those results to non-ignorably missing covariate data. We present a clinical trials example with three partially observed laboratory markers which are used as covariates to predict survival.
The Efficient Integration of Abundance and Demographic Data
Authors: Besbeas P. , Lebreton J.-D. , Morgan B. J. T. 
Published: March 2003

Summary
A drawback of a new method for integrating abundance and mark–recapture–recovery data is the need to combine likelihoods describing the different data sets. Often these likelihoods will be formed by using specialist computer programs, which is an obstacle to the joint analysis. This difficulty is easily circumvented by the use of a multivariate normal approximation. We show that it is only necessary to make the approximation for the parameters of interest in the joint analysis. The approximation is evaluated on data sets for two bird species and is shown to be efficient and accurate.
Differential Analysis of Unemployment Duration with Emphasis on Long‐Term Unemployment
Authors: Bienvenue Jean‐Yves , Carter Lucette , Favereau Olivier , Zighera Jacques 
Published: March 2003

This paper presents a summary of results derived from a study supported by the Labour Ministry (MIRE Convention) on data (comprising about 3 million registrations) from the French ANPE (Agence Nationale Pour l'Emploi). A principal focus was the long term unemployment duration. The first part of the paper is devoted to a brief description of a generalization of the classical segmentation method to take into account the competing exit modes. This method provides a prognostical stratification as well as an analysis of the individual factors “effects” (simple and multiple) on unemployment duration. A short description of the main results is then presented.
Institutional Dynamics in European Industrial Relations
Authors: Nagelkerke Ad G. , De Nijs Willem F. 
Published: March 2003

Since the end of the 1970s, all European systems of industrial relations have experienced some common developments. In order to shed some light on this subject we look for common as well as specific changes within some selected systems of industrial relations in Europe. Therefore, we deal with the moving forces behind these tendencies which are, on the whole, global in character. We discuss the institutional responses to these general developments in the United Kingdom, France, and Germany. These countries have been chosen because their industrial relations are generally seen as belonging to different types of systems.We conclude that many responses are still national specific and, in line with the distinguished national logics of collective action, to be defined respectively as the logic of contract, the logic of opposition and the logic of cooperation. At the end some reflections about the future of European industrial relations are presented.
The Effects of Domestic Violence on Women’s Employment
Authors: Lloyd Susan 
Published: March 2003

This article presents some results of a random household survey that examined the effects of domestic violence on the labor force participation of 824 women living in a low‐income neighborhood. It also uses data from twenty‐four long interviews.Eighteen percent of the respondents reported having experienced physical aggression in the past twelve months, and 11.9% reported more severe physical violence. Women who reported abuse were more likely to have experienced unemployment and held more jobs and to report more health problems. They also had lower personal incomes, and were significantly more likely to receive public assistance. At the same time, women who reported abuse were employed in roughly the same numbers as those who did not. Thus, it appears that domestic violence may depress women’s socioeconomic and occupational status attainment over time, but does not affect employment status per se. The article concludes with comments about the implications of the findings for the redesign of public assistance and job training programs.
Financial Constraints, Aggregate Supply, and the Monetary Transmission Mechanism
Authors: Delli Gatti Domenico , Gallegati Mauro 
Published: March 2003

We derive two propositions identifying the conditions for monetary policy effectiveness due to the interaction of real and financial markets. The first proposition shows that, in a regime of endogenous money, monetary policy is effective even if policy moves are anticipated because changes in the interest rate impinge upon long‐run output.The second proposition shows that in a regime of exogenous money—in which central banks control base money and structural parameters affecting the behaviour of banks—monetary policy affects output if its impact on money is different from its impact on credit.
The Macroeconomics of the East Asian Crisis and the Implications of the Crisis for Macroeconomic Theory
Authors: Lim Joseph Y. 
Published: March 2003

In the first part of the paper I argue that the afflicted East Asian countries’ opening up to short‐term international capital flows resulted not only in financial vulnerabilities, which have been emphasized as the cause of the crisis, but also in macroeconomic weaknesses that contributed to the eruption of the crisis. These macroeconomic weaknesses are in the form of deteriorating foreign exchange earning capabilities, coupled with overvaluation of the currencies. The overvaluation led to distortion in relative prices that contributed to the speculative bubbles.In the second part of the paper I argue strongly that Keynes’s theories are very relevant to the present crisis. They include Keynes’s denial of the dichotomy between the real and monetary sectors, and the speculative demand for money and its role in the ‘liquidity’ and ‘investment’ traps. Most important is Keynes’s neglected psychological and ‘animal spirits’ factors, which were discussed in Chapter 12 of The General Theory. A rereading of this chapter shows that Keynes’s analysis is stronger and more perceptive than the ‘market failure’ analysis of Stiglitz, Rodrik and Krugman in arguing for strong financial regulation and supervision, as well as capital controls of short‐term international flows. The monetarist and rational expectations schools of thought are strongly criticized. These schools of thought paradoxically were the theoretical bases for the initial monetary and fiscal austerity measures imposed on the afflicted countries, which deepened and prolonged their crisis. Finally I also briefly discuss the implications of the crisis on the endogenous growth models and on the economics of institutions and governance.
The Question of Internationalism in Philosophy and Aesthetics
Authors: Diffey T.J. 
Published: March 2003

In this article aesthetics is treated purely as a branch of philosophy, and the points made are intended to apply both to philosophy more generally and aesthetics more specifically. The manner in which internationalism obviously has to do with the organization of the disciplines is discussed. Does it have any bearing on their content or substance? The distinction between organization and content is probed and seen to be much less obvious than at first sight apparent and is doubtfully tenable.Nations are foreign to philosophy in two respects. First we would remain philosophically impoverished if we attended only to the philosophy produced in our own nation. Secondly, and more interestingly, nations cannot be the subject of philosophy since they are individuals. Individuals can only be of philosophical interest in so far as they can be identified under general categories; then what matters is the category, not the individual. Philosophy, including philosophy of art, can only be interested in individuals as first‐order examples or illustrations of more general second‐order claims or theses.So nations must be excluded from the domain of philosophy. It does not follow that such exclusion amounts to internationalism. Indeed though internationalism itself might be a philosophical idea the dismissal of nations as philosophically irrelevant more obviously represents a commitment to universalism than to internationalism. Internationalism and universalism should not be confused though they overlap. Universalism is the ideal of the so‐called enlightenment project which is defended in this paper against post‐modernist criticism and also against the charge that it constitutes a view from nowhere. The view from nowhere is in the strictest sense utopian and for that reason is to be championed as a means for criticising our current assumptions and beliefs and not dismissed.Overt bias including national bias is not a problem, though the writer of philosophy must strive against it on pain of failing to write philosophy. A writer, however, can only guard against overt prejudice and bias. But a text, whether or not philosophical, is also silently exclusionary, that is, there are groups it silently excludes. At a later date the reader can often detect examples of silent exclusion. Since these silences are indefinitely many, it is always possible for a group to feel excluded. The important philosophical point is to concede the possibility of linguistic and indeed conceptual exclusion, to study its mechanisms and to consider on what principles, if any, a moral charge of exclusion is justified and when not.