Reluctance Accelerator Efficiency Optimization via Pulse Shaping

Reluctance accelerators are used to apply linear forces to ferromagnetic projectiles via solenoids. Ef ciency increases for a single-stage reluctance accelerator were produced by manipulating the input current pulse supplied by a discharging capacitor. The development of a theoretical model allowed for the calculation of optimized pulse shapes. A digital pulsewidth modulated switching method was used to control the current pulse shape using an Arduino Uno microcontroller, which supplied signals to the gate of a MOSFET transistor that controlled the current to the system solenoid. An ef ciency increase of 5.7% was obtained for a reluctance accelerator with an optimized current pulse shape in comparison to a capacitor discharge with no pulse shapin

Upper Airways Microbiota in Antibiotic-Naive Wheezing and Healthy Infants from the Tropics of Rural Ecuador

Background: Observations that the airway microbiome is disturbed in asthma may be confounded by the widespread use of antibiotics and inhaled steroids. We have therefore examined the oropharyngeal microbiome in early onset wheezinginfants from a rural area of tropical Ecuador where antibiotic usage is minimal and glucocorticoid usage is absent. Materials and Methods: We performed pyrosequencing of amplicons of the polymorphic bacterial 16S rRNA gene from oropharyngeal samples from 24 infants with non-infectious early onset wheezing and 24 healthy controls (average age 10.2 months). We analyzed microbial community structure and differences between cases and controls by QIIME software. Results: We obtained 76,627 high quality sequences classified into 182 operational taxonomic units (OTUs). Firmicutes was the most common and diverse phylum (71.22% of sequences) with Streptococcus being the most common genus (49.72%). Known pathogens were found significantly more often in cases of infantile wheeze compared to controls, exemplified by Haemophilus spp. (OR = 2.12, 95% Confidence Interval (CI) 1.82–2.47; P = 5.46610223) and Staphylococcus spp. (OR = 124.1, 95%CI 59.0–261.2; P = 1.876102241). Other OTUs were less common in cases than controls, notably Veillonella spp. (OR = 0.59, 95%CI = 0.56–0.62; P = 8.06610286). Discussion: The airway microbiota appeared to contain many more Streptococci than found in Western Europe and the USA. Comparisons between healthy and wheezing infants revealed a significant difference in several bacterial phylotypes that were not confounded by antibiotics or use of inhaled steroids. The increased prevalence of pathogens such as Haemophilus and Staphylococcus spp. in cases may contribute to wheezing illnesses in this age group

Is prophylaxis of early-onset group B streptococcal disease appropriate for South Africa?

Background. Early-onset group B streptococcal (GBS) disease in neonates can be prevented by the use of intrapartum chemoprophylaxis. There are two prevention strategies, one based on risk factors and the other on culture screening for GBS. This study sought to establish whether GBS chemoprophylaxis is appropriate in a developing country such as South Africa.Methods. All neonates with early-onset GBS disease born at Johannesburg Hospital between 1 January 1995 and 21 December 1997 were reviewed. Data were collected prospectively between 1 January and 31 October 1998. Data included demographic information, obstetric information, disease characteristics, admission details and mortality. The approximate cost of implementing both strategies was determined.Results. The overal incidence of early-onset GBS was 1.16 per 1 000 live births. The rate was significantly greater in 1998 compared with the previous years. Most of the babies were born preterm (70%), and 60% required admission to the neonatal intensive care unit (lCU) (a total of 81 ICU days). Twelve of the babies died. Assuming that chemoprophylaxis would reduce the number of ICU days by half, this would save an amount of R52 000. Culture based chemoprophylaxis would cost R1O million, whereas an approach based on risk factors would cost R31140.Conclusion. In conclusion, we feel that early-onset GBS disease is sufficiently prevalent in our unit to justify the implementation of a chemoprophylaxis strategy based on risk factors. Whether other units should adopt a similar approach would depend on the local incidence of earlyonset GBS

Arsenic on the Hands of Children after Playing in Playgrounds

Increasing concerns over the use of wood treated with chromated copper arsenate (CCA) in playground structures arise from potential exposure to arsenic of children playing in these playgrounds. Limited data from previous studies analyzing arsenic levels in sand samples collected from CCA playgrounds are inconsistent and cannot be directly translated to the amount of children’s exposure to arsenic. The objective of this study was to determine the quantitative amounts of arsenic on the hands of children in contact with CCA-treated wood structures or sand in playgrounds. We compared arsenic levels on the hands of 66 children playing in eight CCA playgrounds with levels of arsenic found on the hands of 64 children playing in another eight playgrounds not constructed with CCA-treated wood. The children’s age and duration of playtime were recorded at each playground. After play, children’s hands were washed in a bag containing 150 mL of deionized water. Arsenic levels in the hand-washing water were quantified by inductively coupled plasma mass spectrometry. Our results show that the ages of the children sampled and the duration of play in the playgrounds were similar between the groups of CCA and non-CCA playgrounds. The mean amount of water-soluble arsenic on children’s hands from CCA playgrounds was 0.50 μg (range, 0.0078–3.5 μg). This was significantly higher (p < 0.001) than the mean amount of water-soluble arsenic on children’s hands from non-CCA playgrounds, which was 0.095 μg (range, 0.011–0.41 μg). There was no significant difference in the amount of sand on the children’s hands and the concentration of arsenic in the sand between the CCA and non-CCA groups. The higher values of arsenic on the hands of children playing in the CCA playgrounds are probably due to direct contact with CCA-treated wood. Washing hands after play would reduce the levels of potential exposure because most of the arsenic on children’s hands was washed off with water. The maximum amount of arsenic on children’s hands from the entire group of study participants was < 4 μg, which is lower than the average daily intake of arsenic from water and food

Letters to Andrew Inglis Clark, Tasmania, from Pope Alexander Cooper, Brisbane, 3 June 1905 - 30 Aug 1906

Letters to Andrew Inglis Clark, Tasmania, from Pope Alexander Cooper, Brisbane, 3 June 1905 - 30 Aug 1906, regarding Cooper's attempt to have Queensland judges exempted from income tax. C4/C37-3

Using e-cigarettes for smoking cessation : evaluation of a pilot project in the North West of England

Aims: E-cigarettes have been advocated as an effective smoking cessation intervention, with evidence indicating that they are substantially less harmful than conventional cigarettes. As a result, a pilot to encourage people to swap from conventional cigarettes to e-cigarettes was conducted in 2018 in a socially deprived area in the North West of England. This evaluation highlights the key findings from the pilot. Methods: An analysis of secondary data at 4 weeks (n = 1022) was undertaken to predict those who used solely used e-cigarettes (i.e. had quit tobacco, as confirmed by a carbon monoxide test, CO < 10 ppm) from baseline characteristics, using chi-square tests and logistic regression. Baseline data were demographics, smoking levels and service provider type. Results: Of the 1022 participants who engaged with the pilot 614 were still engaged at 4 weeks, of whom 62% had quit; quitting was more likely in younger participants (aged 18–24) and less likely in those who were sick and disabled. Of those who still smoked tobacco at week 4 (n = 226), smoking had reduced from a baseline of 19.1 cigarettes/day to 8.7. Overall, 37% (381) of those initially enrolled were confirmed to be using an e-cigarette on its own at follow-up. Successful quit was associated with occupation (unemployed, 33% vs intermediate, 47%, p = .023) and residing in the less deprived quintiles of deprivation (50% vs 34% in the most deprived quintile, p = .016). Conclusions: Making the conservative assumption that all those not in contact at 4 weeks were still smoking tobacco, for every five people entering the scheme, three people stayed on the programme and reduced their cigarette smoking and one person cut out tobacco altogether. E-cigarettes appear to be an effective nicotine replacement therapy; however, further research is required to determine whether e-cigarette users are more likely to reduce their overall nicotine consumption in the longer term

Importance of elastic finite-size effects: Neutral defects in ionic compounds

Small system sizes are a well-known source of error in density functional theory (DFT) calculations, yet computational constraints frequently dictate the use of small supercells, often as small as 96 atoms in oxides and compound semiconductors. In ionic compounds, electrostatic finite-size effects have been well characterized, but self-interaction of charge-neutral defects is often discounted or assumed to follow an asymptotic behavior and thus easily corrected with linear elastic theory. Here we show that elastic effects are also important in the description of defects in ionic compounds and can lead to qualitatively incorrect conclusions if inadequately small supercells are used; moreover, the spurious self-interaction does not follow the behavior predicted by linear elastic theory. Considering the exemplar cases of metal oxides with fluorite structure, we show that numerous previous studies, employing 96-atom supercells, misidentify the ground-state structure of (charge-neutral) Schottky defects. We show that the error is eliminated by employing larger cells (324, 768, and 1500 atoms), and careful analysis determines that elastic, not electrostatic, effects are responsible. The spurious self-interaction was also observed in nonoxide ionic compounds irrespective of the computational method used, thereby resolving long-standing discrepancies between DFT and force-field methods, previously attributed to the level of theory. The surprising magnitude of the elastic effects is a cautionary tale for defect calculations in ionic materials, particularly when employing computationally expensive methods (e.g., hybrid functionals) or when modeling large defect clusters. We propose two computationally practicable methods to test the magnitude of the elastic self-interaction in any ionic system. In commonly studied oxides, where electrostatic effects would be expected to be dominant, it is the elastic effects that dictate the need for larger supercells: greater than 96 atoms

A methodology pruning the search space of six compiler transformations by addressing them together as one problem and by exploiting the hardware architecture details

Today’s compilers have a plethora of optimizations-transformations to choose from, and the correct choice, order as well parameters of transformations have a significant/large impact on performance; choosing the correct order and parameters of optimizations has been a long standing problem in compilation research, which until now remains unsolved; the separate sub-problems optimization gives a different schedule/binary for each sub-problem and these schedules cannot coexist, as by refining one degrades the other. Researchers try to solve this problem by using iterative compilation techniques but the search space is so big that it cannot be searched even by using modern supercomputers. Moreover, compiler transformations do not take into account the hardware architecture details and data reuse in an efficient way. In this paper, a new iterative compilation methodology is presented which reduces the search space of six compiler transformations by addressing the above problems; the search space is reduced by many orders of magnitude and thus an efficient solution is now capable to be found. The transformations are the following: loop tiling (including the number of the levels of tiling), loop unroll, register allocation, scalar replacement, loop interchange and data array layouts. The search space is reduced (a) by addressing the aforementioned transformations together as one problem and not separately, (b) by taking into account the custom hardware architecture details (e.g., cache size and associativity) and algorithm characteristics (e.g., data reuse). The proposed methodology has been evaluated over iterative compilation and gcc/icc compilers, on both embedded and general purpose processors; it achieves significant performance gains at many orders of magnitude lower compilation time

Effect of low-compression balls on wheelchair tennis match-play

The purpose of this study was to compare court-movement variables and physiological responses to wheelchair tennis match-play when using low versus standard compression tennis balls. Eleven wheelchair basketball players were monitored during repeated bouts of tennis (20-minutes) using both ball types. Graded and peak exercise tests were completed. For match-play, a data logger was used to record distance and speed. Individual linear heart rate oxygen consumption relationships were used to estimate match-play oxygen uptake. Significant main effects for ball type revealed that total distance (P<0.05), forwards distance (P<0.05), and average speed (P<0.05) were higher for play using a low compression ball. A lower percentage of total time was spent stationary (P<0.001), with significantly more time spent at speeds of 1 to 1.49 (P<0.05), 1.5 to 1.99 (P<0.05) and 2.0 to 2.49 (P<0.05) m∙sec-1 when using the low compression ball. Main effects for physiological variables were not significant. Greater total and forwards distance, and higher average speeds are achieved using a low compression ball. No difference in measured HR and estimated physiological responses indicates that players move further and faster at no additional mean physiological cost. This type of ball will be useful for novice players in the early phases of skill development