Reachability for partially observable discrete time stochastic hybrid systems

When designing optimal controllers for any system, it is often the case that the true state of the system is unknown to the controller. Imperfect state information must be taken into account in the controller’s design in order to preserve its optimality. The same is true when performing reachability calculations. To estimate the probability that the state of a stochastic system reaches, or stays within, some set of interest in a given time horizon, it is necessary to find a controller that drives the system to that set with maximum probability, given the controller’s knowledge of the true state of the system. To date, little work has been done on stochastic reachability calculations with partially observable states. The work that has been done relies on converting the reachability optimization problem to one with an additive cost function, for which theoretical results are well known. Our approach is to preserve the multiplicative cost structure when deriving a sufficient statistic that reduces the problem to one of perfect state information. Our transformation includes a change of measure that simplifies the distribution of the sufficient statistic conditioned on its previous value. We develop a dynamic programming recursion for the solution of the equivalent perfect information problem, proving that the recursion is valid, an optimal solution exists, and results in the same solution as to the original problem. We also show that our results are equivalent to those for the reformulated additive cost problem, and so such a reformulation is not required.     

Ergonomic Office Design and Aging: A Quasi-Experimental Field Study of Employee Reactions to an Ergonomics Intervention Program.

A naturally occurring quasi-experimental longitudinal field study of 87 municipal employees using pretest and posttest measures investigated the effects of an office workstation ergonomics intervention program on employees' perceptions of their workstation characteristics, levels of persistent pain, eyestrain, and workstation satisfaction. The study examined whether reactions differed between younger and older employees. Results revealed that workstation improvements were associated with enhanced perceptions of the workstation's ergonomic qualities, less upper back pain, and greater workstation satisfaction. Among those experiencing an improvement, the perceptions of workstation ergonomic qualities increased more for younger than older employees, supporting the "impressionable years" framework in the psychological literature on aging. Implications for human resources managers are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hidden from the wind and enjoying the water (藏风得水): the traditional cosmology of fengshui and the shaping of Dong villages in Southwestern China

When organising their villages, the Dong interpret the natural environment from a culture-based perspective within their traditional cosmology. This paper explores the metaphorical meanings of the winds, the water of life and the awareness of life breath qi as they are integrated into the practice of fengshui. These principles are applied by the Dong people when organising their villages, monuments and vernacular architecture. This paper particularly examines several Dong communities that share similar topography but were developed in strikingly different ways. In conclusion, this paper argues that the approach of the Dong, when siting their villages, is based on their traditional cosmology and the context of local culture but also their interpretation responding to specific situations that produce different solutions.     

Bimanual motor coordination in agenesis of the corpus callosum.

The nature and extent of deficiencies in bimanual motor coordination in individuals with agenesis of the corpus callosum (ACC) was studied using the computerized Bimanual Coordination Test (cBCT). Compared with previous bimanual tasks, the cBCT is more specifically reliant on interhemispheric interactions of lateralized motor control, allows more precise measurement, and permits examination of performance over a wider range of bimanual challenges. The cBCT performance of 13 high-functioning individuals with complete ACC was compared to 21 age- and IQ-matched controls. The groups did not differ in unimanual response speed. On trials involving angled paths that require bimanual coordination, the ACC group performed significantly slower and less accurately across all angles. The largest group differences in speed occurred on trials where the hands must respond symmetrically, while mirror-image (vs. parallel) responding produced the greatest deficits in accuracy. These data confirm previous findings of deficits in bimanual coordination in callosal absence, but using significantly improved measurement technology. Deficits in bimanual coordination in ACC are present across different demands for interhand interactions in the speed and direction of movement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining immediate and long-term efficacy of rape prevention programming with racially diverse college men.

The authors investigated the short- and long-term (5-month) effectiveness of a theoretically driven, programmatic rape prevention intervention on a sample of primarily White and Black college men. A racially diverse sample was included, and the potential effectiveness of both a culturally relevant and a traditional "colorblind" intervention was assessed. In contrast to earlier investigations, which have consistently reported an overall rebound of scores at the follow-up assessment, results from a hierarchical cluster analysis indicated 3 patterns of treatment response: improving, deteriorating, and rebounding. Results also indicated that Black students in the culturally relevant treatment condition were more cognitively engaged in the intervention than their peers in the traditional treatment condition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mesothelioma-associated antiphospholipid antibody syndrome presenting with cutaneous infarction and neuropathy

OBJECTIVE: To evaluate for the presence of oxidatively modified lipid-protein complexes in endometriosis and endometrium of women with endometriosis and controls. DESIGN: Controlled clinical study. SETTING: Academic tertiary care center. PATIENT(S): Women undergoing surgery for pelvic pain, infertility, endometriosis, or tubal ligation controls. INTERVENTION(S): Biopsy of endometrium and endometriosis. MAIN OUTCOME MEASURE(S): Staining with antibodies to oxidatively modified lipid proteins (HNE-7, MDA2), macrophages (HAM-56), and muscle cell actin (HHF-35). RESULT(S): Both endometrium and endometriosis tissues contain stromal cells that immunostain with HAM-56 and show immunostaining (both intracellular and extracellular) with HNE-7 and MDA2. Some endometriotic implants show patchy staining with HHF-35. Endometrium was devoid of staining with HHF-35. Control staining with nonimmune sera in both tissues was also devoid of staining. CONCLUSION(S): These data strongly implicate the occurrence of oxidative stress in endometriosis tissue. These data also suggest that oxidative modification is a normal physiological process in endometrium.     

Controller performance assessment by frequency domain techniques

A system identification based method for assessing the performance of closed-loop systems is proposed, utilizing measures which coincide naturally with classical and modern frequency domain design specifications. Standard robust control system design methodologies seek to maximize closed-loop performance, subject to strict robustness requirements and include specifications for bandwidth and peak magnitude of the sensitivity and complementary sensitivity functions. Estimates of these transfer functions can be obtained by exciting the reference input with a zero mean, pseudo random binary sequence, observing the process output and error response, and developing a closed-loop model. Performance assessment is based on the comparison between the observed frequency response characteristics and the design specifications. Selection of appropriate model structures, experiment design, and model validation which will ensure reasonable estimates of the closed-loop transfer functions are considered in this paper. A case study involving the performance assessment of a packed bed tubular reactor control system is presented.     

Supplementary feeding at milking and minimum milking interval effects on cow traffic and milking performance in a pasture-based automatic milking system

In extensive pastoral dairy farming systems herds graze 12 months of the year with the majority fed a near-100% pasture or conserved pasture diet. The viability of automatic milking in these systems will depend partly upon the amount of supplementary feed necessary to encourage cows to walk from the pasture to the milking unit but also on the efficient use of the automatic milking system (AMS). This paper describes a study to determine the importance of offering concentrate in the milking unit and the effect of minimum milking interval on cow movement and milking performance in a pasture-based AMS. The effects of feeding rate (FR0=0 kg or FR1=1 kg crushed barley/d) and minimum milking interval (MM6=6 h or MM12=12 h) on cow movement and behaviour during milking were studied in a multi-factorial cross-over (feeding level only, 4 weeks per treatment) experiment involving 27 mixed-breed cows milked through a single AMS. Feeding 1 kg barley in the milking unit resulted in a higher visiting frequency to the pre-selection unit (FR0=4.6 visits/d, FR1=5.4 visits/d, sed=0.35, P<0.05) and a higher yield (FR0=22.5 kg/d, FR1=23.6 kg/d, sed=0.385, P<0.01) but had no effect on milking frequency (FR0=1.6 milkings/d, FR1=1.7 milkings/d, sed=0.04, NS). Minimum milking interval was the major factor influencing milking frequency (MM6=1.9, MM12=1.4 milkings/d, sed=0.15, P<0.01). The absence of feeding in the milking unit had no negative effect on behaviour during milking or the number of cows that had to be manually driven from the paddock. The results show that automatic milking can be combined with a near-100% pasture diet and that milking interval is an important determinant for maximizing milk harvested per AMS.