Solar energy in photosynthesis

Solar energy provides the reducing power within green leaves to convert CO₂ and H₂O into sugars. The CO₂ is supplied by the atmosphere and enters the leaf by diffusion. Factors affecting the rate of photosynthesis must either change the CO₂ diffusive resistances or the CO₂ concentration gradient along the diffusion pathways. Therefore, these effects can be described in terms of diffusive control mechanisms.

Light affects CO₂ diffusion by initiating photosynthesis, which removes CO₂ at the chloroplast and establishes a diffusion gradient. Light also triggers stomatal opening, thereby sharply decreasing the diffusive resistance. However, intense radiation can cause desiccation of stomatal guard cells, a mechanism whereby the diffusive resistance increases.

During illumination, leaf cells have both a source (respiration) and sink (photosynthesis) for CO₂. Respiration in some species appears to be greatly stimulated by light. This additional internal CO₂ flux is a possible reason for a lower efficiency of energy utilization than in species whose respiration is not enhanced by light.

Physiological growth responses or movements often occur that position leaves in the light. Plants lacking this capability are often excluded in ecological succession in nature.     

On-line decision support for take-off runway scheduling with uncertain taxi times at London Heathrow airport

This paper addresses the challenge of building an automated decision support methodology to tackle the complex problem faced every day by runway controllers at London Heathrow Airport. Aircraft taxi from stands to holding areas at the end of the take-off runway where they wait in queues for permission to take off. A runway controller attempts to find the best order for aircraft to take off. Sequence-dependent separation rules that depend upon aircraft size, departure route and speed group ensure that this is not a simple problem to solve. Take-off time slots on some aircraft and the need to avoid excessive delay for any aircraft make this an even more complicated problem. Making this decision at the holding area helps to avoid the problems of unpredictable push-back and taxi times, but introduces a number of complex spatial constraints that would not otherwise exist. The holding area allows some flexibility for interchange of aircraft between queues, but this is limited by its physical layout. These physical constraints are not usually included in academic models of the departure problem. However, any decision support system to support the take-off runway controller must include them. We show, in this paper, that a decision support system could help the controllers to significantly improve the departure sequence at busy times of the day, by considering the taxiing aircraft in addition to those already at the holding area. However, undertaking this re-introduces the issue of taxi time uncertainty, the effect of which we explicitly measure in these experiments. Empirical results are presented for experiments using real data from different times of the day, showing how the performance of the system varies depending upon the volume of traffic and the accuracy of the provided taxi time estimations. We conclude that the development of a good taxi time prediction system is key to maximising the benefits, although benefits can be observed even without this.     

Variability across sources of performance ratings: Further evidence.

33 1st-yr graduate students (aged 21–55 yrs) completed a simulated counseling interview. Self-, peer, and supervisor ratings were obtained for the simulated interviews using 7 measures of counseling performance. A multiple analysis of variance (MANOVA) indicated statistically significant differences among self-, peer, and supervisor ratings. Analyses also showed significant differences on 4 of the 7 dependent measures. Implications for training are discussed. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Advancing mental health in political places.

The author describes his career as a psychologist serving in elected office. He found that by his attending to individual concerns, supporting community consensus on key issues, playing the outsider role, leading an issue individually, and calling media attention to a problem, city hall could be moved to action. In the state legislature, the author serves in the minority but has made an impact by amending legislation, sponsoring less controversial bills, or generating enough public support for a bill that the majority advances its own similar bill. He identified the following mental health needs in Ohio: better understanding by legislators of the nature and impact of mental illness, adequate funding, mental health parity legislation, and more effective advocacy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thiamine and Fatty Acid Content of Lake Michigan Chinook Salmon

Nutritional status of Lake Michigan Chinook salmon (Oncorhynchus tshawytscha) is inadequately documented. An investigation was conducted to determine muscle and liver thiamine content and whole body fatty acid composition in small, medium and large Chinook salmon. Muscle and liver thiamine concentrations were highest in small salmon, and tended to decrease with increasing fish size. Muscle thiamine was higher in fall than spring in large salmon. The high percentage of Chinook salmon (24–32% in fall and 58–71% in spring) with muscle thiamine concentration below 500 pmol/g, which has been associated with loss of equilibrium and death in other Great Lake salmonines, suggest that Chinook appear to rely less on thiamine than other Great Lakes species for which such low concentrations would be associated with thiamine deficiency (Brown et al. 2005b). A positive correlation was observed between liver total thiamine and percent liver lipids (r = 0.53, P < 0.0001, n = 119). In medium and large salmon, liver lipids were observed to be low in fish with less than 4,000 pmol/g liver total thiamine. In individuals with greater than 4,000 pmol/g liver thiamine, liver lipid increased with thiamine concentration. Individual fatty acids declined between fall and spring. Essential omega-3 fatty acids appear to be conserved as lipid content declined. Arachidonic acid (C20:4n6), an essential omega-6 fatty acid was not different between fall and spring, although the sum of omega-6 (Sw6) fatty acids declined over winter. Elevated concentrations of saturated fatty acids (sum) were observed in whole body tissue lipid. In summary, thiamine, a dietary essential vitamin, and individual fatty acids were found to vary in Lake Michigan Chinook salmon by fish size and season of the year.     

Perceptual consequences of an illness-concern induction and its relation to hypochondriacal tendencies.

This article examines the perceptual consequences of activating illness concern as a function of hypochondriacal tendencies. In 2 independent samples, hypochondriacal tendencies were associated with slower reaction times on a modified emotional Stroop task when the stimulus words were illness related, but only when illness concern was activated. Moreover, these findings emerged when hypochondriacal tendencies were defined as a sensitivity to bodily sensations. When defined as illness preoccupation and fear, hypochondriacal tendencies were associated with a generalized pattern of perseveration to all stimuli when health concern was activated. Finally, the results persisted even after statistically controlling for state anxiety. Findings are discussed within the context of an activation hypothesis and highlight the importance of the operational definition and assessment of hypochondriacal tendencies when examining perceptual biases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure mode and effects analysis in the U.K. motor industry: A state-of-the-art study

This paper reports the main findings of a questionnaire survey on the use of failure mode and effects analysis (FMEA) in the United Kingdom motor industry. Survey data were obtained from 78 organizations. Among the main findings are: the majority of suppliers only started to use FMEA because it was a contractual requirement of their customer; however, a number of them are now seeking to make more use of the technique to facilitate their process of quality improvement; FMEA is treated by the majority of organizations as a team activity; engineers still view FMEA as a hard slog; more use should be made of computerized aids to reduce the effort in preparing and updating the FMEA; and the main difficulties encountered in the use of FMEA are related to time constraints, poor organizational understanding of the importance of FMEA, inadequate training and lack of management commitment. It is also pointed out that organizations are not satisfied with the current training courses on FMEA.     

Sr2YRu1−uCuuO6: Evidence for SrO-Layer Superconductivity

Sr₂YRuO₆ doped on its Ru site by Cu superconducts at the below ～45 K, although its Ru and Cu are magnetically ordered at ～23 K and ～86 K, respectively. The SrO layers superconduct. Ba₂GdRuO₆, when doped with Cu, does not superconduct, because L = 0 Gd is not crystal-field split, and so induces Cooper pair-breaking.     

How shape constancy relates to drawing accuracy.

There is increasing evidence that the major source of drawing errors lies in the initial perception of the to-be-drawn object. In four experiments, the authors explore the relation between an artist's susceptibility to perceptual transformations, as measured by a simple shape constancy task, and drawing accuracy. The data reveal a robust negative relation between errors on the shape constancy task and drawing accuracy in general, and specifically the accuracy of the rendering of spatial relations. The data further suggest that the perceptual processes that lead to errors on the shape constancy task occur during the initial encoding of the stimuli. The authors conclude that the shape constancy task likely measures one's ability to overcome constructive perception processes that transform the retinal image into a final percept, and that this ability is necessary for the accurate rendering of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)