Conserved- and zero-mean quadratic quantities in oscillatory systems

We study quadratic functionals of the variables of a linear oscillatory system and their derivatives. We show that such functionals are partitioned in conserved quantities and in trivially- and intrinsic zero-mean quantities. We also state an equipartition of energy principle for oscillatory systems

State maps for linear systems

Modeling of physical systems consists of writing the equations describing a phenomenon and yields as a result a set of differential-algebraic equations. As such, state-space models are not a natural starting point for modeling, while they have utmost importance in the simulation and control phase. The paper addresses the problem of computing state variables for systems of linear differential-algebraic equations of various forms. The point of view from which the problem is considered is the behavioral one, as put forward in [J. C. Willems, Automatica J. IFAC, 22 (1986), pp. 561–580; DynamicsReported,2(1989),pp.171–269;IEEETrans.Automat.Control,36(1991),pp. 259–294]

Development and validation of EMP-3 : an instrument to measure physicians' attitudes towards ethnic minority patients

Background and Objectives: The growing diversity of patient populations challenges health care providers. Physicians' attitudes and perceptions toward cultural diversity in health care could be partly contributing to difficulties in communication between physicians and ethnic minority patients. To evaluate these attitudes and perceptions, an instrument was developed and validated. Methods: A preliminary version of the instrument was developed through literature research and expert consultation and completed by 112 family physicians. Factor analysis was performed and reliability and construct validity tested. Results: The instrument revealed three factors that were interpreted as: (1) physicians' task perception and ideas on cultural differences in health and health care, (2) physicians' attitudes toward physician-patient communication with minority patients, and (3) physicians' perception of minority patients' needs in communication. Moderate but significant correlations were found between factors of the EMP-3 and practice organization, practice location, and physicians' gender. Several factors of the Jefferson Empathy Scale, the Patient Practitioner Orientation Scale, and the Health Beliefs and Attitude Scale related to the first two factors of the EMP-3. Conclusions: This instrument, designed specifically to measure physicians' attitudes toward cultural diversity, showed moderate validity and reliability results. Further adaptations and evaluation could be useful

Algorithms for deterministic balanced subspace identification

New algorithms for identification of a balanced state space representation are proposed. They are based on a procedure for the estimation of impulse response and sequential zero input responses directly from data. The proposed algorithms are more efficient than the existing alternatives that compute the whole Hankel matrix of Markov parameters. It is shown that the computations can be performed on Hankel matrices of the input–output data of various dimensions. By choosing wider matrices, we need persistency of excitation of smaller order. Moreover, this leads to computational savings and improved statistical accuracy when the data is noisy. Using a finite amount of input–output data, the existing algorithms compute finite time balanced representation and the identified models have a lower bound on the distance to an exact balanced representation. The proposed algorithm can approximate arbitrarily closely an exact balanced representation. Moreover, the finite time balancing parameter can be selected automatically by monitoring the decay of the impulse response. We show what is the optimal in terms of minimal identifiability condition partition of the data into “past” and “future”

The canonical controller and its regularity

This paper deals with properties of canonical controllers. We first specify the behavior that they implement. It follows that a canonical controller implements the desired controlled behavior if and only if the desired behavior is implementable. We subsequently investigate the regularity of the controlled behavior. We prove that a canonical controller is regular if and only if every controller is regular. In other words, canonical controllers are maximally irregular

Socio-economic status of the patient and doctor-patient communication: does it make a difference?

A

Balanced state representations with polynomial algebra

Algorithms are derived which pass directly from the differential equation describing the behavior of a finite-dimensional linear system to a balanced state representatio