Segmentation of the mean of heteroscedastic data via cross-validation

This paper tackles the problem of detecting abrupt changes in the mean of a heteroscedastic signal by model selection, without knowledge on the variations of the noise. A new family of change-point detection procedures is proposed, showing that cross-validation methods can be successful in the heteroscedastic framework, whereas most existing procedures are not robust to heteroscedasticity. The robustness to heteroscedasticity of the proposed procedures is supported by an extensive simulation study, together with recent partial theoretical results. An application to Comparative Genomic Hybridization (CGH) data is provided, showing that robustness to heteroscedasticity can indeed be required for their analysis.     

Estimating the Number of Block Boundaries from Diagonal Blockwise Matrices Without Penalization

In computational biology, numerous recent studies have been dedicated to the analysis of the chromatin structure within the cell by two‐dimensional segmentation methods. Motivated by this application, we consider the problem of retrieving the diagonal blocks in a matrix of observations. The theoretical properties of the least squares estimators of both the boundaries and the number of blocks are investigated. More precisely, the contribution of the paper is to establish the consistency of these estimators. A surprising consequence of our results is that, contrary to the one‐dimensional case, a penalty is not needed for retrieving the true number of diagonal blocks. Finally, the results are illustrated on synthetic data.     

ILP formulation of the degree-constrained minimum spanning hierarchy problem

Given a connected edge-weighted graph G and a positive integer B, the degree-constrained minimum spanning tree problem (DCMST) consists in finding a minimum cost spanning tree of G such that the degree of each vertex in the tree is less than or equal to B. This problem, which has been extensively studied over the last few decades, has several practical applications, mainly in networks. However, some applications do not especially impose a subgraph as a solution. For this purpose, a more flexible so-called hierarchy structure has been proposed. Hierarchy, which can be seen as a generalization of trees, is defined as a homomorphism of a tree in a graph. In this paper, we discuss the degree-constrained minimum spanning hierarchy (DCMSH) problem which is NP-hard. An integer linear program (ILP) formulation of this new problem is given. Properties of the solution are analysed, which allows us to add valid inequalities to the ILP. To evaluate the difference of cost between trees and hierarchies, the exact solution of DCMST and z problems are compared. It appears that, in sparse random graphs, the average percentage of improvement of the cost varies from 20 to 36% when the maximal authorized degree of vertices B is equal to 2, and from 11 to 31% when B is equal to 3. The improvement increases as the graph size increases.     

Care giving and nursing, work conditions and Humanitude®

Increased lifespan in western societies causes the increase of hospitalization in the old age, notably for patient showing forms of dementia including Altzheimer disease. These patients relate poorly to care givers and nurses, and cases of maltreatment have repeatedly been reported. To prevent abuse and increase patient's quality of life, Gineste and Pelissier (2007) proposed a philosophy of care based on the Humanitude? concept. Acknowledging that being human is being vertical and related to other humans, the pillars of Humanitude? are gaze, touch, talk, and standing. These modes of relation are systematically developed in care giving techniques derived from the concept. After several studies in geriatric hospitals, to assess psychosocial and ergonomic aspects of work, we present an analysis of the gap between the logic of human care and the logic of hospital organization, impacting employees work conditions and psychological welfare. Care giving is not only a "one to one" relation with the patient but needs to be integrated in the whole organization. Psychologists and ergonomists should be instrumental in defining the project and the organization linking human care giving towards the patients and better work conditions for healthcare employees.     

Social responsibility and work conditions: building a reference label, Démarche T®

Corporate Social Responsibility (CSR) is now considered in large and global companies and the recent publication of the ISO 26000 standard clarifies the targets. Based on our consultancy's experience for fifteen years in ergonomics mainly in French small and medium enterprises, we developed a label to coax and value efforts of companies in dealing with health and safety at the work place as required by ISO 26000 paragraph 6.4. The formal approach of ISO describes what should be achieved but gives no cue on how actual conditions of work should be improved. The label, called Démarche T (ie Process W where W stands for work) aims the management of work conditions as a process, giving visibility and credit to companies for their continuous involvement in the matter. We describe the items and processes that are part of our assessment. We first conduct an ergonomic diagnosis including the analysis of records on health, physical and psychological well-being, observations at the workplace and interviews with the workers. This diagnosis is followed by recommendations. The fulfillment of these is assessed yearly. Items under assessment include: - ergonomics, health and safety in the companies statements and their impact in actual project management; - relations with workers through the committee for health and safety; - actual results on health, safety and work conditions. On a local level, we give the companies passing the label a competitive edge in recruiting better candidates motivated by good work conditions, and help them fulfill ISO 26000 requirements, an increasingly decisive advantage to benefit from public regional and European support. Our paper describes the diagnosis and follow-up process.     

Two-step values for games with two-level communication structure

TU games with two-level communication structure, in which a two-level communication structure relates fundamentally to the given coalition structure and consists of a communication graph on the collection of the a priori unions in the coalition structure, as well as a collection of communication graphs within each union, are considered. For such games we introduce two families of two-step values inspired by the two-step procedures staying behind the Owen value (Owen, in: Henn, Moeschlin (eds) Essays in mathematical economics and game theory, Springer, Berlin, pp 76–88, 1977) and the two-step Shapley value (Kamijo in Int Game Theory Rev 11:207–214, 2009) for games with coalition structure. Our approach is based on the unified treatment of several component efficient values for games with communication structure and it generates two-stage solution concepts that apply component efficient values for games with communication structure on both distribution levels. Comparable axiomatic characterizations are provided.     

Coalitional desirability and the equal division value

Theory and Decision - We introduce three natural collective variants of the well-known axiom of desirability (Maschler and Peleg in Pac J Math 18:289–328, 1966), which require that if the...     

Pathological Gamblers: Inpatients’ versus Outpatients’ Characteristics

Several researchers and clinicians have questioned the advantages and disadvantages of inpatient and outpatient treatment for people suffering from pathological gambling. This study compares the characteristics of pathological gamblers seeking inpatient and outpatient treatment. A total of 233 pathological gamblers (inpatients = 134, outpatients = 99) participated in the study. Results show that inpatients have more severe gambling problems than those receiving outpatient services. Similar results were obtained on most other related variables such as anxiety, depression, alcohol consumption, and comorbidity. These results are discussed in terms of the costs and benefits of these two treatment modalities.     

A professionalization framework to understand the structuring of work

The notion of professionalization is widely used both by managers and researchers. This use questions the traditional definition of profession. This paper reviews a book published in 1988 – The System of Professions – written by a sociologist, A. Abbott. Though this book had a strong impact in the field of the sociology of professions, it has remained unknown by many researchers in management science. His pragmatic approach to the concepts of profession and professionalization helps achieve better understanding of work structuring and as a consequence can be useful to address issues such as human resources management, organizational control or even the management of information systems.     

Improving prediction performance of stellar parameters using functional models

This paper investigates the problem of prediction of stellar parameters, based on the star's electromagnetic spectrum. The knowledge of these parameters permits to infer on the evolutionary state of the star. From a statistical point of view, the spectra of different stars can be represented as functional data. Therefore, a two-step procedure decomposing the spectra in a functional basis combined with a regression method of prediction is proposed. We also use a bootstrap methodology to build prediction intervals for the stellar parameters. A practical application is also provided to illustrate the numerical performance of our approach.