Estimation of the Intensity Parameter of the Germ‐Grain Quermass‐Interaction Model when the Number of Germs is not Observed

The Quermass‐interaction model allows to generalize the classical germ‐grain Boolean model in adding a morphological interaction between the grains. It enables to model random structures with specific morphologies, which are unlikely to be generated from a Boolean model. The Quermass‐interaction model depends in particular on an intensity parameter, which is impossible to estimate from classical likelihood or pseudo‐likelihood approaches because the number of points is not observable from a germ‐grain set. In this paper, we present a procedure based on the Takacs–Fiksel method, which is able to estimate all parameters of the Quermass‐interaction model, including the intensity. An intensive simulation study is conducted to assess the efficiency of the procedure and to provide practical recommendations. It also illustrates that the estimation of the intensity parameter is crucial in order to identify the model. The Quermass‐interaction model is finally fitted by our method to P. Diggle's heather data set.     

Rethinking the nation and international relations: The space of nation states

Efforts to move sociology beyond the nation state and international relations theory have both been plagued by several limitations and dualisms. Recent research has begun to find ways beyond the problems by turning to Pierre Bourdieu's relational conception of social structure and practice. Yet one specific relational structure forming a key part of the puzzle has been neglected or merely implicitly assumed so far: the space of nation states. After clarifying the structural-constructivist nature of this concept, we aim to specify it by constructing an empirical model of the contemporary space of nation states using a specially compiled dataset and tools of geometric data analysis. The analysis reveals the distribution of powers on the world scene, and more specifically, the uneven possession of two varieties of “meta-capital” understood as capacities to regulate the value and exchangeability of certain capitals and to decree what even defines a legitimate “state”. We argue that the nation state, which is accurately understood as a contingent construct and well-founded fiction from a Bourdieusian viewpoint, should not be excluded when analyzing the expression and reproduction of contemporary global power relations.     

The impact of remittances from Canada's seasonal workers programme on Mexican farms

Based on a survey of participants in Canada's Seasonal Agricultural Workers Program, the authors’ three‐stage least squares estimation of a simultaneous equation model finds that migrants’ remittances enhance on‐farm investments in Mexico, which, in turn, increase farm income. Remittances are also found to have a positive influence on non‐farm income in Mexico, by giving respondents the possibility of starting a new business and diversifying their investments. These results support the hypothesis underlying the “new economics of labour migration” that remittances contribute to economic development by relaxing the credit constraint on the investment function of family farms.     

What fuels the fire: Job- or task-specific motivation (or both)? On the hierarchical and multidimensional nature of teacher motivation in relation to job burnout

Drawing on a hierarchical (job and task level) and multidimensional conceptualisation of work motivation (intrinsic, identified, introjected, and external regulations), this study examines relationships between motivational regulations and burnout. Participants were 806 French-Canadian teachers working in public elementary and high schools. Results reveal different associations between burnout and the regulations that drive teachers to engage in their overall job or in specific tasks: autonomous regulations (intrinsic and identified) are negatively associated with burnout but more negatively at the job than task level, whereas controlled regulations (introjected and external) are positively associated with burnout but more positively at the task than job level. This study provides valuable insights into how teachers’ motivations towards both the job and tasks can foster or prevent burnout symptoms. Implications for theory and research on burnout and work motivation are discussed.     

A Bayesian dose‐finding design for drug combination clinical trials based on the logistic model

In early phase dose‐finding cancer studies, the objective is to determine the maximum tolerated dose, defined as the highest dose with an acceptable dose‐limiting toxicity rate. Finding this dose for drug‐combination trials is complicated because of drug–drug interactions, and many trial designs have been proposed to address this issue. These designs rely on complicated statistical models that typically are not familiar to clinicians, and are rarely used in practice. The aim of this paper is to propose a Bayesian dose‐finding design for drug combination trials based on standard logistic regression. Under the proposed design, we continuously update the posterior estimates of the model parameters to make the decisions of dose assignment and early stopping. Simulation studies show that the proposed design is competitive and outperforms some existing designs. We also extend our design to handle delayed toxicities. Copyright © 2014 John Wiley & Sons, Ltd.     

Incremental exercise tests in master athletes and untrained older adults

This study aimed to analyze the impact of step-duration protocols, 1-min vs. 3-min, on cardiorespiratory responses to exercise, whatever the aerobic-fitness level of sedentary (65.5 +/- 2.3 years, n = 8) or highly fit (63.1 +/- 3.2 years, n = 19) participants. Heart rate and VO2 at the first and second ventilatory thresholds (VT1 ,VT2) and maximal exercise were not significantly different between the two protocols. In master athletes, the 3-min protocol elicited significantly lower ventilation at VT2 and maximal exercise (p < .01). In the latter, breathlessness was also lower at maximal exercise (p < .05) than in sedentary participants. In trained or sedentary older adults, VT1, VT2, and were not influenced by stage duration. According to the lower breathlessness and ventilation, however, the 3-min step protocol could be more appropriate in master athletes. In untrained participants, because the cardiorespiratory responses were similar with the two incremental exercise tests, either of them could be used.     

Public Administration and Organizational Theory: Prescribing the Proper Dose

Public Organization Review - Since the founding of the field of public administration, scholars have struggled with questions related to the “publicness” of public organizations...     

Modelling Aggregation on the Large Scale and Regularity on the Small Scale in Spatial Point Pattern Datasets

We consider a dependent thinning of a regular point process with the aim of obtaining aggregation on the large scale and regularity on the small scale in the resulting target point process of retained points. Various parametric models for the underlying processes are suggested and the properties of the target point process are studied. Simulation and inference procedures are discussed when a realization of the target point process is observed, depending on whether the thinned points are observed or not. The paper extends previous work by Dietrich Stoyan on interrupted point processes.     

Interspecies Extrapolation: A Reexamination of Acute Toxicity Data

We reanalyze the acute toxicity data on cancer chemotherapeutic agents compiled by Freireich et al.(1) and Schein et al.(2) to derive coefficients of the allometric equation for scaling toxic doses across species (toxic dose = a.[body weight]b). In doing so, we extend the analysis of Travis and White (Risk Analysis, 1988, 8, 119-125) by addressing uncertainties inherent in the analysis and by including the hamster data, previously not used. Through Monte Carlo sampling, we specifically account for measurement errors when deriving confidence intervals and testing hypotheses. Two hypotheses are considered: first, that the allometric scaling power (b) varies for chemicals of the type studied; second, that the same scaling power, or "scaling law," holds for all chemicals in the data set. Following the first hypothesis, in 95% of the cases the allometric power of body weight falls in the range from 0.42-0.97, with a population mean of 0.74. Assuming the second hypothesis to be true-that the same scaling law is followed for all chemicals-the maximum likelihood estimate of the scaling power is 0.74; confidence bounds on the mean depend on the size of measurement error assumed. Under a "best case" analysis, 95% confidence bounds on the mean are 0.71 and 0.77, similar to the results reported by Travis and White. For alternative assumptions regarding measurement error, the confidence intervals are larger and include 0.67, but not 1.00. Although a scaling power of about 0.75 provides the best fit to the data as a whole, a scaling power of 0.67, corresponding to scaling per unit surface area, is not rejected when the nonhomogeneity of variances is taken into account. Hence, both surface area and 0.75 power scaling are consistent with the Freireich et al. and Schein et al. data sets. To illustrate the potential impact of overestimating the scaling power, we compare reported human MTDs to values extrapolated from mouse LD10s.     

Testing for residual correlation of any order in the autoregressive process

We are interested in the implications of a linearly autocorrelated driven noise on the asymptotic behavior of the usual least-squares estimator in a stable autoregressive process. We show that the least-squares estimator is not consistent and we suggest a sharp analysis of its almost sure limiting value as well as its asymptotic normality. We also establish the almost sure convergence and the asymptotic normality of the estimated serial correlation parameter of the driven noise. Then, we derive a statistical procedure enabling to test for correlation of any order in the residuals of an autoregressive modelling, giving clearly better results than the commonly used portmanteau tests of Ljung–Box and Box–Pierce, and appearing to outperform the Breusch–Godfrey procedure on small-sized samples.