Intermediate electron transport in Porphyridium: EPR studies

Measurement of photosynthetic electron transport in Porphyridium by EPR electron paramagnetic resonanc

Feedback and time are essential for the optimal control of computing systems

The performance, reliability, cost, size and energy usage of computing systems can be improved by one or more orders of magnitude by the systematic use of modern control and optimization methods. Computing systems rely on the use of feedback algorithms to schedule tasks, data and resources, but the models that are used to design these algorithms are validated using open-loop metrics. By using closed-loop metrics instead, such as the gap metric developed in the control community, it should be possible to develop improved scheduling algorithms and computing systems that have not been over-engineered. Furthermore, scheduling problems are most naturally formulated as constraint satisfaction or mathematical optimization problems, but these are seldom implemented using state of the art numerical methods, nor do they explicitly take into account the fact that the scheduling problem itself takes time to solve. This paper makes the case that recent results in real-time model predictive control, where optimization problems are solved in order to control a process that evolves in time, are likely to form the basis of scheduling algorithms of the future. We therefore outline some of the research problems and opportunities that could arise by explicitly considering feedback and time when designing optimal scheduling algorithms for computing systems

Robustly stable feedback min-max model predictive control

Published versio

Supervisees' and supervisors' experiences of group climate in group supervision in psychotherapy. Effects of admission procedure

The purpose of this study was to evaluate the effects of two different admission procedures (high school grades/scholastic aptitude test (SAT) versus high school grades/SAT + interview) to a program in professional psychology on students' and supervisors' experiences of the group climate in psychotherapy supervision groups during an eighteen-month clinical practicum. A self-rating scale constructed to measure experiences of group climate in group supervision in psychotherapy was used. The results showed that students who were admitted based on the alternative admission procedure reported that their supervision groups had a more beneficial climate compared to those who were admitted based on high school grades/SAT. The evaluation suggested that admission via interviews together with high school grades/SAT is a good alternative to traditional admission procedures

Prevalence of childhood abuse among people who are homeless in Western countries: a systematic review and meta-analysis

Purpose: This article systematically reviews studies of prevalence of childhood experience of physical and sexual abuse in adult people who are homeless in Western countries. Methods: Medline, PsychInfo, and the Cochrane Library were searched using the keywords: homeless*, child* abuse, child* trauma, and child* adversity and the bibliographies of identified articles were reviewed. Sources of heterogeneity in the prevalence rates were explored by meta-regression analysis Results: Twenty-four reports published between January 1990 and August 2013 in three countries provided estimates obtained from up to 9,730 adult individuals who were homeless. Prevalence of reported childhood physical abuse ranged from 6 to 94% with average prevalence of 37%, 95% CI [25, 51]. Reported sexual abuse ranged from 4 to 62%, with average prevalence estimated as 32%, 95% CI [23, 44] for females and 10% for males, 95% CI [6, 17]. Substantial heterogeneity was observed among the studies (I2 ≥ 98%). Including moderators greatly reduced but did not eliminate this heterogeneity. Moderator analyses suggested that reported physical abuse tended to be higher for predominately white samples and tended to be lower for younger samples. Sexual abuse was far more prevalent in predominately female samples and slightly higher in non-US samples and convenience samples

Optimal Active Control of a Wave Energy Converter

Abstract-This paper investigates optimal active control schemes applied to a point absorber wave energy converter within a receding horizon fashion. A variational formulation of the power maximization problem is adapted to solve the optimal control problem. The optimal control method is shown to be of a bang-bang type for a power take-off mechanism that incorporates both linear dampers and active control elements. We also consider a direct transcription of the optimal control problem as a general nonlinear program. A variation of the projected gradient optimization scheme is formulated and shown to be feasible and computationally inexpensive compared to a standard NLP solver. Since the system model is bilinear and the cost function is non-convex quadratic, the resulting optimization problem is not a convex quadratic program. Results will be compared with an optimal command latching method to demonstrate the improvement in absorbed power. Time domain simulations are generated under irregular sea conditions

A Warm-start Interior-point Method for Predictive Control

In predictive control, a quadratic program (QP) needs to be solved at each sampling instant. We present a new warm-start strategy to solve a QP with an interior-point method whose data is slightly perturbed from the previous QP. In this strategy, an initial guess of the unknown variables in the perturbed problem is determined from the computed solution of the previous problem. We demonstrate the effectiveness of our warm-start strategy to a number of online benchmark problems. Numerical results indicate that the proposed technique depends upon the size of perturbation and it leads to a reduction of 30–74% in floating point operations compared to a cold-start interior-point method