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Interest Lies (interest + ly)

Distribution by Scientific Domains
Mathematics and Statistics66%
Humanities and Social Sciences22%

Selected Abstracts

Projecting the risk of future climate shifts

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2006
David B. Enfield
Abstract Recent research has shown that decadal-to-multidecadal (D2M) climate variability is associated with environmental changes that have important consequences for human activities, such as public health, water availability, frequency of hurricanes, and so forth. As scientists, how do we convert these relationships into decision support products useful to water managers, insurance actuaries, and others, whose principal interest lies in knowing when future climate regime shifts will likely occur that affect long-horizon decisions? Unfortunately, numerical models are far from being able to make deterministic predictions for future D2M climate shifts. However, the recent development of paleoclimate reconstructions of the Atlantic Multidecadal Oscillation (AMO) (Gray et al., 2004) and Pacific Decadal Oscillation (PDO); (MacDonald and Case, 2005) give us a viable alternative: to estimate probability distribution functions from long climate index series that allow us to calculate the probability of future D2M regime shifts. In this paper, we show how probabilistic projections can be developed for a specific climate mode,the AMO as represented by the Gray et al. (2004) tree-ring reconstruction. The methods are robust and can be applied to any D2M climate mode for which a sufficiently long index series exists, as well as to the growing body of paleo-proxy reconstructions that have become available. The target index need not be a paleo-proxy calibrated against a climate index; it may profitably be calibrated against a specific resource of interest, such as stream flow or lake levels. Copyright © 2006 Royal Meteorological Society [source]

The Social and Private Worlds of Speech: Speech for Inter- and Intramental Activity

MODERN LANGUAGE JOURNAL, Issue 3 2007
HEATHER J. SMITH
During a study designed to examine the processes of learning English as an additional language as manifest in the interactive behaviour of small groups of bilingual school children playing specially designed board games, several instances of private speech were captured. Private speech is commonly described as speech addressed to the self for intramental purposes. Unlike many studies, this research was not specifically aimed at eliciting private speech. Indeed, the overtly social nature of game playing probably acted to limit the production of speech for intramental purposes. In effect, therefore, interest lies in the fact that private speech was produced within this context. The article presents an examination of the functions of the private speech produced and the consequences of such outward verbalisation within this interactive group activity. As a result, a heuristic model of the relationship between speech for social and private purposes is proposed. [source]

LIVING A DISTRIBUTED LIFE: MULTILOCALITY AND WORKING AT A DISTANCE

ANNALS OF ANTHROPOLOGICAL PRACTICE, Issue 1 2008
Brigitte Jordan
In the last few years, new collaboration and communication technologies have led to a deterritorialization of work, allowing for the rise of new work- and lifestyles. In this article, I use my own transition from the life of a corporate researcher to that of a multilocal mobile consultant for tracking some of the patterns I see in a changing cultural and economic environment where work and workers are no longer tied to a specific place of work. My main interest lies in identifying some of the behavioral shifts that are happening as people are caught up in and attempt to deal with this changing cultural landscape. Writing as a knowledge worker who now moves regularly from a work,home place in the Silicon Valley of California to another in the tropical lowlands of Costa Rica, I use my personal transition as a lens through which to trace new, emergent patterns of behavior, of values, and of social conventions. I assess the stresses and joys, the upsides and downsides, the challenges and rewards of this work- and lifestyle and identify strategies for making such a life successful and rewarding. Throughout, there emerges an awareness of the ways in which the personal patterns described reflect wider trends and cumulatively illustrate global transformation of workscapes and lifescapes. These types of local patterns in fact constitute the on-the-ground material reality of global processes that initiate and sustain widespread culture change and emergent societal transformations. [source]

Conditional length distributions induced by the coverage of two points by a Poisson Voronoļ tessellation: application to a telecommunication model

APPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 4 2006
Catherine Gloaguen
Abstract The end points of a fixed segment in the Euclidian plane covered by a Poisson Voronoļ tessellation belong to the same cell or to two distinct cells. This marks off one or two points of the underlying Poisson process that are the nucleus(i) of the cell(s). Our interest lies in the geometrical relationship between these nuclei and the segment end points as well as between the nuclei. We investigate their probability distribution functions conditioning on the number of nuclei, taking into account the length of the segment. The aim of the study is to establish some tools to be used for the analysis of a telecommunication problem related to the pricing of leased lines. We motivate and give accurate approximations of the probability of common coverage and of the length distributions that can be included in spreadsheet codes as an element of simple cost functions. Copyright © 2006 John Wiley & Sons, Ltd. [source]

KERNEL DENSITY ESTIMATION WITH MISSING DATA AND AUXILIARY VARIABLES

AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 3 2009
Suzanne R. Dubnicka
Summary In most parametric statistical analyses, knowledge of the distribution of the response variable, or of the errors, is important. As this distribution is not typically known with certainty, one might initially construct a histogram or estimate the density of the variable of interest to gain insight regarding the distribution and its characteristics. However, when the response variable is incomplete, a histogram will only provide a representation of the distribution of the observed data. In the AIDS Clinical Trial Study protocol 175, interest lies in the difference in CD4 counts from baseline to final follow-up, but CD4 counts collected at final follow-up were incomplete. A method is therefore proposed for estimating the density of an incomplete response variable when auxiliary data are available. The proposed estimator is based on the Horvitz,Thompson estimator, and the propensity scores are estimated nonparametrically. Simulation studies indicate that the proposed estimator performs well. [source]

Regression Analysis with a Misclassified Covariate from a Current Status Observation Scheme

BIOMETRICS, Issue 2 2010
Leilei Zeng
Summary Naive use of misclassified covariates leads to inconsistent estimators of covariate effects in regression models. A variety of methods have been proposed to address this problem including likelihood, pseudo-likelihood, estimating equation methods, and Bayesian methods, with all of these methods typically requiring either internal or external validation samples or replication studies. We consider a problem arising from a series of orthopedic studies in which interest lies in examining the effect of a short-term serological response and other covariates on the risk of developing a longer term thrombotic condition called deep vein thrombosis. The serological response is an indicator of whether the patient developed antibodies following exposure to an antithrombotic drug, but the seroconversion status of patients is only available at the time of a blood sample taken upon the discharge from hospital. The seroconversion time is therefore subject to a current status observation scheme, or Case I interval censoring, and subjects tested before seroconversion are misclassified as nonseroconverters. We develop a likelihood-based approach for fitting regression models that accounts for misclassification of the seroconversion status due to early testing using parametric and nonparametric estimates of the seroconversion time distribution. The method is shown to reduce the bias resulting from naive analyses in simulation studies and an application to the data from the orthopedic studies provides further illustration. [source]

A Two-Part Joint Model for the Analysis of Survival and Longitudinal Binary Data with Excess Zeros

BIOMETRICS, Issue 2 2008
Dimitris Rizopoulos
Summary Many longitudinal studies generate both the time to some event of interest and repeated measures data. This article is motivated by a study on patients with a renal allograft, in which interest lies in the association between longitudinal proteinuria (a dichotomous variable) measurements and the time to renal graft failure. An interesting feature of the sample at hand is that nearly half of the patients were never tested positive for proteinuria (,1g/day) during follow-up, which introduces a degenerate part in the random-effects density for the longitudinal process. In this article we propose a two-part shared parameter model framework that effectively takes this feature into account, and we investigate sensitivity to the various dependence structures used to describe the association between the longitudinal measurements of proteinuria and the time to renal graft failure. [source]

Marginalized Models for Moderate to Long Series of Longitudinal Binary Response Data

BIOMETRICS, Issue 2 2007
Jonathan S. Schildcrout
Summary Marginalized models (Heagerty, 1999, Biometrics55, 688,698) permit likelihood-based inference when interest lies in marginal regression models for longitudinal binary response data. Two such models are the marginalized transition and marginalized latent variable models. The former captures within-subject serial dependence among repeated measurements with transition model terms while the latter assumes exchangeable or nondiminishing response dependence using random intercepts. In this article, we extend the class of marginalized models by proposing a single unifying model that describes both serial and long-range dependence. This model will be particularly useful in longitudinal analyses with a moderate to large number of repeated measurements per subject, where both serial and exchangeable forms of response correlation can be identified. We describe maximum likelihood and Bayesian approaches toward parameter estimation and inference, and we study the large sample operating characteristics under two types of dependence model misspecification. Data from the Madras Longitudinal Schizophrenia Study (Thara et al., 1994, Acta Psychiatrica Scandinavica90, 329,336) are analyzed. [source]

Percolation for the vacant set of random interlacements

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 6 2009
Vladas Sidoravicius
We investigate random interlacements on ,d, d , 3. This model, recently introduced in [8], corresponds to a Poisson cloud on the space of doubly infinite trajectories modulo time shift tending to infinity at positive and negative infinite times. A nonnegative parameter u measures how many trajectories enter the picture. Our main interest lies in the percolative properties of the vacant set left by random interlacements at level u. We show that for all d , 3 the vacant set at level u percolates when u is small. This solves an open problem of [8], where this fact has only been established when d , 7. It also completes the proof of the nondegeneracy in all dimensions d , 3 of the critical parameter u* of [8]. © 2008 Wiley Periodicals, Inc. [source]