Simulations of autoignition and laminar premixed flames in methane/air mixtures diluted with hot products

This paper considers constant-pressure autoignition and freely propagating premixed flames of cold methane-air mixtures mixed with equilibrium hot products at high enough dilution levels that the combustion enters the MILD combustion regime. The analysis is meant to provide further insight on MILD regime boundaries and to identify the effect of hot products speciation. As the mass fraction of hot products in the reactants mixture increases, autoignition occurs earlier. Species profiles show that the products-reactants mixture approximately equilibrates to a new state over a quick transient well before the main autoignition event, but as dilution becomes very high, this equilibration transient becomes more prominent and eventually merges with the primary ignition event. The dilution level at which these two reactive zones merge corresponds well with that marking the transition into the MILD regime, as defined according to conventional criteria. Similarly, premixed flame simulations at high dilutions show evidence of significant reactions involving intermediate species prior to the flame front. Since the premixed flame governing equations system demands that the species and temperature gradients be zero at the “cold” boundary, flame speed cannot be calculated above a certain dilution level. Up to this point, which again agrees reasonably well with the transition into the MILD regime according to convention, the laminar burning velocity was found to increase with hot product dilution while flame thickness remained largely unchanged. Some comments on the MILD combustion regime boundary definition for gas turbine applications are included.This work has been partly funded by Rolls-Royce plc.This is the accepted manuscript. The final version is available from Taylor & Francis at http://www.tandfonline.com/doi/abs/10.1080/00102202.2014.883217#.VMexAIXziEo

Drug administration errors by South African anaesthetists - a survey

Objectives. To investigate the incidence, nature of and factors contributing towards wrong drug administrations by South African anaesthetists. Design. A confidential, self-reporting survey was sent out to the 720 anaesthetists on the database of the South African Society of Anaesthesiologists. Results. A total of 133 questionnaires were returned for analysis (18.5% response rate). Of the respondents, 125 (94%) admitted to having inadvertently administered a wrong drug. Thirty respondents (22.6%) said they had made errors on at least four occasions. A total of 303 specific wrong drug administrations were described. Nearly 50% involved muscle relaxants. A further 43 incidents (14%) involved the erroneous administration of vasoactive drugs. Five deaths and 3 nonfatal cardiac arrests were reported. In 9.9% of incidents the anaesthetic time was prolonged by more than 30 minutes. Contributory causes identified included syringe swaps (40%), misidentification of drugs (27.1%), fatigue (14.1%), distractions (4.7%), and mislabelling of syringes (4.7%). Only 19% of respondents regularly use colour-coded syringe labels complying with the national standard. Conclusions. Most anaesthetists experienced at least one drug error. The incidence of wrong drug administrations by South African anaesthetists appears to be similar to that in Australasia and Canada. The commonest error was a ‘syringe swap' involving muscle relaxants. Most drug errors are inconsequential. An important minority of incidents result in severe morbidity or death. The study supports efforts to improve ampoule labelling, to encourage the use of syringe labels based on the international colour code and to develop a national reporting system for such incidents. South African Medical Journal Vol. 96(7) 2006: 630-63

Drug administration errors by South African anaesthetists – a survey

No Abstract. Southern African Journal of Anaesthesia and Analgesia Vol. 12(1) 2006: 4

Experimental assessment of the lean blow-off in a fully premixed annular combustor

The behaviour of the flame in an annular combustor with multiple bluff-body injectors with swirl was investigated to provide insights into lean blow-off (LBO) mechanisms when flames interact. Two different configurations, with 12 and 18 burners, and various bulk velocities and equivalence ratios were tested. Flame shape and main features were studied by means of 5 KHz OH$^*$ chemiluminescence imaging and the stability limits were identified and compiled into regime diagrams. As the equivalence ratio of the mixture was reduced the individual flames would first exhibit a transition from a stable ``W-shape" state to a stable ``V-shape" state before becoming unstable close to extinction. In the 18-burner configuration LBO was characterised by random detachment and re-stabilisation of the flame over multiple burners across the chamber, until complete lift-off. In the 12-burner configuration the flame anchors on a few burners in azimuthally symmetric locations, making the overall flame less prone to extinguish. Finally, the stability curves were computed using a correlation based on the Damkholer (Da) number and compared to single burner configurations. The beginning of the blow-off transient was found to be similar to the LBO condition for a single burner in the 12-burner setup, while the 18-burner configuration was less stable for all the conditions investigated. However, it was found that correlations based on single burner extinction data do not fully work for the extinction of interacting flames. The results provide insights into the blow-off of realistic gas turbine engines and can be used for validating models of such processes.EU Marie Skłodowska-Curie Grant Agreement No. 76599

Vulnerable diseases affecting child mortality in Sierra Leone: emerging health issue

Child mortality in Sierra Leone is the highest ranked in the world. The main causes for child mortality are maternal factors, environmental factors and health factors. Minimal research has been carried out on health factors in Sierra Leone. The objective of this study is to see how maternal and environmental factors have an effect on health factors, which in turn cause child mortality. The data used were from the 2008 Sierra Leone Demographic and Household Survey (SLDHS). The study showed that child mortality had statistically significant factors associated with it: place of residence, birth number, religion and type of toilet facility. Furthermore, the SLDHS had not given much information regarding the cause of diseases affecting children, so we looked only at the effects they had on children. Acute respiratory infections, diarrhoea and measles each had one variable that was statistically significant. As for pneumonia, there were no variables associated with children contracting the disease

Computing power of quantitative trait locus association mapping for haploid loci

<p>Abstract</p> <p>Background</p> <p>Statistical power calculations are a critical part of any study design for gene mapping. Most calculations assume that the locus of interest is biallelic. However, there are common situations in human genetics such as X-linked loci in males where the locus is haploid. The purpose of this work is to mathematically derive the biometric model for haploid loci, and to compute power for QTL mapping when the loci are haploid.</p> <p>Results</p> <p>We have derived the biometric model for power calculations for haploid loci and have developed software to perform these calculations. We have verified our calculations with independent mathematical methods.</p> <p>Conclusion</p> <p>Our results fill a need in power calculations for QTL mapping studies. Furthermore, failure to appropriately model haploid loci may cause underestimation of power.</p

Patient-physician interaction in general practice and health inequalities in a multidisciplinary study: design, methods and feasibility in the French INTERMEDE study

<p>Abstract</p> <p>Background</p> <p>The way in which patients and their doctors interact is a potentially important factor in optimal communication during consultations as well as treatment, compliance and follow-up care. The aim of this multidisciplinary study is to use both qualitative and quantitative methods to explore the 'black box' that is the interaction between the two parties during a general practice consultation, and to identify factors therein that may contribute to producing health inequalities. This paper outlines the original multidisciplinary methodology used, and the feasibility of this type of study.</p> <p>Methods and design</p> <p>The study design combines methodologies on two separate samples in two phases. Firstly, a qualitative phase collected ethnographical and sociological data during consultation, followed by in-depth interviews with both patients and doctors independently. Secondly, a quantitative phase on a different sample of patients and physicians collected data via several questionnaires given to patients and doctors consisting of specific 'mirrored' questions asked post-consultation, as well as collecting information on patient and physician characteristics.</p> <p>Discussion</p> <p>The design and methodology used in this study were both successfully implemented, and readily accepted by doctors and patients alike. This type of multidisciplinary study shows great potential in providing further knowledge into the role of patient/physician interaction and its influence on maintaining or producing health inequalities. The next challenge in this study will be implementing the multidisciplinary approach during the data analysis.</p

Quantum resource estimates for computing elliptic curve discrete logarithms

We give precise quantum resource estimates for Shor's algorithm to compute discrete logarithms on elliptic curves over prime fields. The estimates are derived from a simulation of a Toffoli gate network for controlled elliptic curve point addition, implemented within the framework of the quantum computing software tool suite LIQ$Ui|\rangle$. We determine circuit implementations for reversible modular arithmetic, including modular addition, multiplication and inversion, as well as reversible elliptic curve point addition. We conclude that elliptic curve discrete logarithms on an elliptic curve defined over an $n$-bit prime field can be computed on a quantum computer with at most $9n + 2\lceil\log_2(n)\rceil+10$ qubits using a quantum circuit of at most $448 n^3 \log_2(n) + 4090 n^3$ Toffoli gates. We are able to classically simulate the Toffoli networks corresponding to the controlled elliptic curve point addition as the core piece of Shor's algorithm for the NIST standard curves P-192, P-224, P-256, P-384 and P-521. Our approach allows gate-level comparisons to recent resource estimates for Shor's factoring algorithm. The results also support estimates given earlier by Proos and Zalka and indicate that, for current parameters at comparable classical security levels, the number of qubits required to tackle elliptic curves is less than for attacking RSA, suggesting that indeed ECC is an easier target than RSA.Comment: 24 pages, 2 tables, 11 figures. v2: typos fixed and reference added. ASIACRYPT 201

Positive Interactions between Desert Granivores: Localized Facilitation of Harvester Ants by Kangaroo Rats

Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis) mounds and rough harvester ant (Pogonomyrmex rugosus) colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (<10 m). Mortality risk of vulnerable, recently founded harvester ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species