Aerodynamic preliminary analysis system. Part 2: User's manual and program description

A comprehensive aerodynamic analysis program based on linearized potential theory is described. The solution treats thickness and attitude problems at subsonic and supersonic speeds. Three dimensional configurations with or without jet flaps having multiple nonplanar surfaces of arbitrary planform and open or closed slender bodies or noncircular contour are analyzed. Longitudinal and lateral-directional static and rotary derivative solutions are generated. The analysis is implemented on a time sharing system in conjunction with an input tablet digitizer and an interactive graphics input/output display and editing terminal to maximize its responsiveness to the preliminary analysis problem. Nominal case computation time of 45 CPU seconds on the CDC 175 for a 200 panel simulation indicates the program provides an efficient analysis for systematically performing various aerodynamic configuration tradeoff and evaluation studies

Experimental archeology and serious games: challenges of inhabiting virtual heritage

Experimental archaeology has long yielded valuable insights into the tools and techniques that featured in past peoples’ relationship with the material world around them. However, experimental archaeology has, hitherto, confined itself to rigid, empirical and quantitative questions. This paper applies principles of experimental archaeology and serious gaming tools in the reconstructions of a British Iron Age Roundhouse. The paper explains a number of experiments conducted to look for quantitative differences in movement in virtual vs material environments using both “virtual” studio reconstruction as well as material reconstruction. The data from these experiments was then analysed to look for differences in movement which could be attributed to artefacts and/or environments. The paper explains the structure of the experiments, how the data was generated, what theories may make sense of the data, what conclusions have been drawn and how serious gaming tools can support the creation of new experimental heritage environments

Arthrospira (Spirulina) in tannery wastewaters Part 1: The microbial ecology of tannery waste stabilisation ponds and the management of noxious odour emissions using microalgal capping

We investigated the problem of noxious gas and odour emissions in zero-discharge evaporative tannery waste stabilisation ponds. These have been little-studied systems although they present one of few options for the management of tannery wastewaters in highly water-stressed areas. A three-year study of the microbial ecology of an evaporative waste stabilisation ponding cascade was undertaken and a descriptive account of the biology and the physico-chemical parameters related to odiferous gas release is reported. Large populations of Arthrospira (Spirulina) dominated  the latter facultative ponds in the cascade where odour emission was substantially reduced compared to initial anaerobic ponds. Photosynthetic productivity maxima of up to 9 000 mg∙m-2∙day-1 carbon fixation were measured in bloom conditions. Arthrospira production was associated with an oxygenated, alkaline layer established on the surface of facultative ponds (0.35 m in depth) in which oxidation of sulphide and ammonia, and the trapping of other odour-causing compounds was observed. An attempt was made to achieve comparable odour control in the anaerobic ponds by capping with recirculated microalgae-enriched effluent from facultative ponds. While this was shown to be effective in establishing an Arthrospira-dominant surface layer and an associated control of odour emissions in anaerobic ponds, large recirculation volumes (2:1) were required to maintain the Arthrospira population. Elevated salinity of recirculated facultative pond waters also negatively impacted the evaporative function in the low-salinity initial ponds in the cascade. An alternative method of Arthrospira capping was investigated which involved the construction of a free-standing high rate pond alongside the waste stabilisation pond system, and using a controlled feed of raw tannery effluent for optimising the cultivation of Arthrospira biomass. High biomass productivity was achieved in this unit (12.87 g∙m-2∙day-1), using a low feed to effluent loading volume ratio (0.21:1) and subsequent capping of anaerobic ponds from this source achieved odour control comparable to facultative ponds. This study has shown that management of the odour problem in waste stabilisation ponds is possible and that leather production using the zero-discharge evaporative disposal operation may be compatible with a level of both environmental and social acceptability of these systems. Odour problems, alone, should thus not constrain tanning as one of the few industrial agricultural activities available in rural economies.Keywords: tannery, wastewater, waste stabilisation ponds, odour, noxious gas, Spirulina, Arthrospira, microalgal biomas

Krill-feeding behaviour in a chinstrap penguin compared to fish-eating in Magellanic penguins: a pilot study.

Inferring feeding activities from undulations in diving depth profiles is widespread in studies of foraging marine predators. This idea, however, has rarely been tested because of practical difficulties in obtaining an independent estimate of feeding activities at a time scale corresponding to depth changes within a dive. In this study we attempted to relate depth profile undulations and feeding activities during diving in a single Chinstrap Penguin Pygoscelis antarctica, by simultaneously using a conventional time-depth recorder and a recently developed beak-angle sensor. Although failure in device attachments meant that data were obtained successfully from just a part of a single foraging trip, our preliminary results show a linear relationship between the number of depth wiggles and the number of underwater beakopening events during a dive, suggesting that the relative feeding intensity of each dive could be represented by depth-profile data. Underwater beak-opening patterns of this krill-feeding penguin species are compared with recent data from three fish- and squid-feeding Magellanic Penguins Spheniscus magellanicus

Structural equation modelling of the moderation effect of health locus of control on the pain-depression pathway

Background and aims Low back pain (LBP) is common, and is a major health concern. Psychological consequences of LBP, such as depression, are significant barriers to recovery, but mechanisms for the development of depression are less well understood. One potential mechanism is the individuals’ Health Locus of Control (HLOC), i.e. perception of the level of control an individual has over their health. The aim of this study is to investigate the moderation effect of HLOC on the pain-depression pathway. Methods Cross sectional study of participants (n = 637) from two cohorts of primary care LBP patients. Two Structural Equation Model analysis groups were created (low perceived control, and high perceived control), based on the HLOC Internality Scale. The path model consisted of pain intensity and disability as exogenous predictors, pain interference (endogenous mediator), bothersomeness (endogenous predictor) and depression (outcome). Critical ratio difference tests were applied to the coefficients using pairwise comparisons. Results Both models had an acceptable model fit. Critical ratio tests indicated a significant (p < 0.05) moderation effect, with stronger pathway coefficients for depression for those who report low Internality (β 0.48), compared to those with high Internality (β 0.26). Conclusions HLOC Internality significantly moderates the pain-depression pathway in those with back pain, meaning that those who have a low perception of control report greater levels of depression. This may signify a potential factor that may predict depression among people with pain, and could potentially be a target for intervention

Vacuum-UV negative photoion spectroscopy of CH3F, CH3Cl and CH3Br

Using tunable vacuum-UV radiation from a synchrotron, negative ions are detected by quadrupolar mass spectrometry following photoexcitation of three gaseous halogenated methanes CH$_3$X (X = F,Cl,Br). The anions X$^-$, H$^-$, CX$^-$, CHX$^-$ and CH$_2$X$^-$ are observed, and their ion yields recorded in the range 8-35 eV. The anions show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation, generically described as AB + h$v$ $\rightarrow$ A$^-$ + B$^+$ (+ neutrals). Absolute cross sections for ion-pair formation are obtained by calibrating the signal intensities with those of F$^-$ from both SF$_6$ and CF$_4$. The cross sections for formation of X$^-$ + CH$_3$$^+$ are much greater than for formation of CH$_2$X$^-$ + H$^+$. In common with many quadrupoles, the spectra of $m$/$z$ 1 (H$^-$) anions show contributions from all anions, and only for CH$_3$Br is it possible to perform the necessary subtraction to obtain the true H$^-$ spectrum. The anion cross sections are normalised to vacuum-UV absorption cross sections to obtain quantum yields for their production. The appearance energies of X$^-$ and CH$_2$X$^-$ are used to calculate upper limits to 298 K bond dissociation energies for D$^o$ (H$_3$C-X) and D$^o$ (XH$_2$C-H) which are consistent with literature values. The spectra suggest that most of the anions are formed indirectly by crossing of Rydberg states of the parent molecule onto an ion-pair continuum. The one exception is the lowest-energy peak of F$^-$ from CH$_3$F at 13.4 eV, where its width and lack of structure suggest it may correspond to a direct ion-pair transition

The pain, depression, disability pathway in those with low back pain: a moderation analysis of health locus of control

Low back pain (LBP) is common, impacts on the individual and society, and is a major health concern. Psychological consequences of LBP, such as depression, are significant barriers to recovery, but mechanisms for the development of depression are less well understood. One potential mechanism is the individual’s health locus of control (HLoC), that is, perception of the level of control an individual has over their health. The objective of this study is to investigate the moderation effect of HLoC on the pain–depression–disability pathway in those with LBP. The design is a nested cross-sectional analysis of two existing cohorts of patients (n=637) who had previously consulted their primary care physician about LBP. Measures were taken of HLoC, pain intensity and interference, depression, disability, and bothersomeness. Structural Equation Modeling analysis was applied to two path models that examined the pain to depression to disability pathway moderated by the HLoC constructs of Internality and Externality, respectively. Critical ratio (CR) difference tests were applied to the coefficients using pairwise comparisons. The results show that both models had an acceptable model fit and pathways were significant. CR tests indicated a significant moderation effect, with stronger pathway coefficients for depression for those who report low Internality (β 0.48), compared to those with high Internality (β 0.28). No moderation effects were found within the Externality model. HLoC Internality significantly moderates the pain–depression pathway in those with LBP, meaning that those who have a low perception of control report greater levels of depression. HLoC may signify depression among people with LBP, and could potentially be a target for intervention

Friedman’s “The Social Responsibility of Business is to Increase its Profits”: A Critique for the Classroom

In this paper we examine many of the arguments contained in Milton Friedman’s classic essay, in the form of critiques linked with learning objectives for classroom discussions

Arthrospira (Spirulina) in tannery wastewaters. Part 2: Evaluation of tannery wastewater as production media for the mass culture of Arthrospira biomass

Mass blooms of Arthrospira (Spirulina) have been reported in waste stabilisation ponds treating tannery wastewaters and have been linked to a reduction in odour emissions in these systems. However, these blooms are unstable and unreliable, forming and disappearing in an apparently unpredictable manner, and they have remained poorly understood. Controlled production of Arthrospira biomass in this medium could not only be used to enable a more predictable control of odour in these systems (as detailed in Part 1 of this report), but could also provide a biomass product with external value. Techno-economic studies of microalgal biomass production have identified the cost of growth media formulation as a critical driver in the profitability of the algal biotechnology enterprise. Apart from the potential feed value of Arthrospira biomass as a product, the renewed interest in, and possibly marginal economics of, biofuels production from the microalgae has refocused attention on the possible advantages of wastewater use as low-cost production media. Part 2 of this study reports the investigation of factors regulating Arthrospira growth in the tannery wastewater medium and thus requiring active control in order to optimise biomass production. It was shown that Arthrospira growth in this high-protein, low-carbonate medium is under ammonia control, rather than nutrient limitation, as may previously have been thought. It was also shown that an effective mass culture strategy in this medium would require a maximum effluent loading rate that operates as a function of the optimised ammonia removal rate. Growth optima were demonstrated for ammonia and bicarbonate levels of 20 mg∙ℓ-1 and 12–17 g∙ℓ-1, respectively, and inhibition of growth was demonstrated at ammonia levels above 60 mg∙ℓ-1. Both autotrophic and mixotrophic growth of Arthrospira was observed and organic uptake may contribute to a stimulation of biomass production compared to growth in defined inorganic media. Heavy metal accumulation may present a toxicity hazard where biomass is targeted for use in animal feed rations. A heavy metals removal step was investigated involving the passage of the tannery effluent through an anaerobic sulphide-generating compartment in a primary pond, prior to its use in Arthrospira production. An acceptable Arthrospira feed-grade biomass was produced in this way. These results indicate potential cost-benefit advantages in the use of tannery effluent-based growth media for Arthrospira biomass production, and waste nutrient recovery may mitigate negative energy yield problems where the biomass is further processed in biofuels manufacture.Keywords: Spirulina; Arthrospira; microalgal biomass; biofuels; tannery; wastewater; waste stabilisation pond