1,818 research outputs found

    On rank estimation in semidefinite matrices

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    This work concerns the problem of rank estimation in semidefinite matrices, having either indefinite or semidefinite matrix estimator satisfying a typical asymptotic normality condition. Several rank tests are examined, based on either available rank tests or basic new results. A number of related issues are discussed such as the choice of matrix estimators and rank tests based on finer assumptions than those of asymptotic normality of matrix estimators. Several examples where rank estimation in semidefinite matrices is of interest are studied and serve as guide throughout the work.rank, symmetric matrix, indefinite and semidefinite estimators, eigenvalues, matrix decompositions, estimation, asymptotic normality.

    Local and global rank tests for multivariate varying-coefficient models

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    In a multivariate varying-coefficient model, the response vectors Y are regressed on known functions u(X) of some explanatory variables X and the coefficients in an unknown regression matrix q(Z) depend on another set of explanatory variables Z. We provide statistical tests, called local and global rank tests, which allow to estimate the rank of an unknown regression coefficient matrix q(Z) locally at a fixed level of the variable Z or globally as the maximum rank over all levels of Z, respectively. In the case of local rank tests, we do so by applying already available rank tests to a kernel-based estimator of the coefficient matrix q(z). Global rank tests are obtained by integrating test statistics used in estimation of local rank tests. We present a simulation study where, focusing on global ranks, we examine small sample properties of the considered statistical tests. We also apply our results to estimate the so-called local and global ranks in a demand system where budget shares are regressed on known functions of total expenditures and the coefficients in a regression matrix depend on prices faced by a consumer.varying-coefficient model, kernel smoothing, matrix rank estimation, demand systems, local and global ranks

    Boardroom Cultural Governance: An Examination of the Beliefs and Values of Board Directors and Executive Management in U.S. Based Multinational Corporations (MNCs)

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    In the evolving global economy, boardroom governance has forged an increasing influence on what transpires in corporations today. Within the boardroom, expectations of board directors and executive management (key actors) have shifted dramatically due to the financial failures (i.e., Enron and WorldCom, etc.) and the ensuing global financial crisis in the 2000s. The belief is that these directors and managers contributed greatly to these crises (Boerner, 2011). Consequently, there is a growing appeal to study boardroom governance and the roles of board directors and executive managers, not from a structural description, but rather from a behavioral perspective. In the literature, corporate governance structural framework is well informed while the behavioral framework is lacking. Often referred to as a black box, board behavior is not well understood because board processes are not easily observed nor are researchers readily invited to do so (Barratt & Korac-Kakabadse, 2002). There is therefore a clear call for studies to examine the black box of boardroom governance (Erakovic & Overall, 2010; Lockhart, 2010; Huse et al, 2011). Recognizing this demand, an examination of the beliefs and values of the board directors and executive managers in their boardroom culture, was undertaken as the starting point to open the black box of boardroom governance

    Sanitser, an innovative sanitary ware body, formulated with waste glass and recycled materials

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    Abstract In the present paper, the results of "Sanitser" Life European project are presented. The aim of this study was to reduce the firing temperature for ceramic body (from 1250 to 1170 °C). This was achieved substituting feldspar and quartz with recycled blend materials and a little percentage of flux (less than 3%); in a sanitary ware vitreous china formulation a waste glass, granitic materials and fired broken ceramic pieces were introduced. Tests performed on the Sanitser formulation showed that it has the same final physical-chemical characteristics of the industrial vitreous china (VC) body. Besides, different ceramic pieces (wash basin, bidet and WC pan) were compared with VC production. The results showed that Sanitser body can replace vitreous china in the sanitary ware production. In this project, the firing temperature of the ceramic body is reduced significantly with a supposed decrease of the CO2 emissions. In Sanitser formulation, about 43.6% of recycled materials that would end in dumps were utilized

    Final report of the EURISOL Design Study (2005-2009) A Design Study for a European Isotope-Separation-On-Line Radioactive Ion Beam Facility

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    European Commission Contract N°515768 RIDS Published by GANI

    Dalle Province all’area vasta: un’incoerenza italiana

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    La storia della delimitazione regionale in Italia ci aiuta a capire quanto artificiale possa essere la rappresentazione che di esse hanno i diversi governi regionali. In questo capitolo si procede a una comparazione con quella provinciale, ben piĂč antica, che ci permetta anche di mostrarne il ruolo nella programmazione attuale.The history of regional borders in Italy cans show the artificial representation that their governments propose. For this reason the comparison with the provincial delimitations, older than the first, can help to explain why it is important a deeper reflection about the question to renounce to this institutional level

    Recent Developments of Electrochemical Wall Mass Transfer Probes and Their Application to Drag-Reducing Polymers

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    Electrochemical mass transfer probes are used to measure the velocity gradient at a wall. Recent advances in their application are reviewed. These include corrections for the time response of the probe, the simultaneous measurement at a number of locations of the two components of the fluctuating velocity gradient and a study of the influence of drag reducing polymers on turbulence. It is found that drag-reducing polymers cause an increase in the scale of flow oriented eddies in the viscous sublayer
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