8,244 research outputs found
Aerodynamic characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing at Mach number 0.2
A wind-tunnel of the static longitudinal, lateral and directional stability characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing was conducted in the Langley low-turbulence pressure tunnel. The configuration variables included wing planform, tip fins, center fin, and scramjet engine modules. A mach number of 0.2 was investigated over a Reynolds number (based on fuselage length) range of 2,200,000 to 19.75 x 1,000,000 (with a majority of tests at 10.0 x 1,000,000. Tests were conducted through an angle-of-attack range from about -2 deg to 34 deg at angles of sideslip of 0 deg to 5 deg, and at elevon deflection of 0 deg, -5 deg, -10 deg, -15 deg, and -20 deg. The drag coefficient of the integrated scramjet engine appears relatively constant with Reynolds number at the test Mach number of 0.2. Mild pitch-up was exhibited by the models equipped with tip fins. The forward delta, a highly swept forward portion of the wing, was destabilizing. The center fin model has a higher trimmed maximum lift-drag ratio and a wider trim lift and angle-of-attack range than the tip fin model. Both the tip fin models and center fin models exhibited positive dihedral effect and positive directional stability. Roll control was positive for the tip fin model, but yaw due to roll control was unfavorable
Monte Carlo Simulation of Ising Models with Dipole Interaction
Recently, a new memory effect was found in the metamagnetic domain structure
of the diluted Ising antiferromagnet by domain imaging
with Faraday contrast. Essential for this effect is the dipole interaction. We
simulate the low temperature behavior of diluted Ising-antiferromagnets by a
Monte Carlo simulation considering long range interaction. The metamagnetic
domain structure occurring due to the dipole interaction is investigated by
graphical representation. In the model considered the antiferromagnetic state
is stable for an external magnetic field smaller than a lower boundary
while for fields larger than an upper boundary the system is in the
saturated paramagnetic phase, where the spins are ferromagnetically polarized.
For magnetic fields in between these two boundaries a mixed phase occurs
consisting of ferromagnetic domains in an antiferromagnetic background. The
position of these ferromagnetic domains is stored in the system: after a cycle
in which the field is first removed and afterwards applied again the domains
reappear at their original positions. The reason for this effect can be found
in the frozen antiferromagnetic domain state which occurs after removing the
field.Comment: Latex, 10 pages; 3 postsript-figures, compressed tar-file, uuencoded,
report 10109
The effect of low volume sprint interval training in patients with non-alcoholic fatty liver disease
Objectives: Exercise is an important part of disease management in patients with non-alcoholic fatty liver disease (NAFLD), but adherence to current exercise recommendations is poor. Novel low-volume sprint interval training (SIT) protocols with total training time commitments of ≤30 min per week have been shown to improve cardiometabolic risk and functional capacity in healthy sedentary participants, but the efficacy of such protocols in the management of NAFLD remains unknown. The aim of the present study was to examine whether a low-volume SIT protocol can be used to improve liver function, insulin resistance, body composition, physical fitness, cognitive function and general well-being in patients with NAFLD.Methods: In the present study, 7 men and 2 women with NAFLD (age: 45±8 y, BMI: 28.7±4.1 kg·m−2) completed a 6-week control period followed by 6 weeks of twice-weekly SIT sessions (5-10×6-s ‘all-out’ cycle sprints). Body composition, blood pressure, liver function, metabolic function, functional capacity, cognitive function and quality of life were assessed at baseline, following the control period, and following the SIT intervention.Results: Walking speed during the walk test (+12%), estimated V̇O2max (+8%), verbal fluency (+44%), and blood platelet count (+12%; all p<0.05) significantly increased during the control period. These measures remained significantly raised compared to baseline following the SIT intervention, but did not significantly change any further compared to the post-control time-point. Diastolic blood pressure decreased from 87±10 to 77±8 mm Hg from the end of the control period to the end of the SIT intervention (p<0.05).Conclusion: This study does not support the use of 6 weeks of a low volume SIT protocol involving twice-weekly sessions with 5-10×6-s ‘all-out’ cycle sprints as an intervention for NAFLD disease management
The role of empathy for learning in complex Science|Environment|Health contexts
This is the final version. Available on open access from Taylor & Francis via the DOI in this recordRecent research on motivation to learn science shows that science teaching usually supports students’ systemising, but not their empathising cognition. In this paper we argue that empathy, with due caution, should be emphasised in science learning more seriously and consistently, particularly in a Science|Environment|Health pedagogy that aims at fostering the mutual benefit between the three interlinked educational fields. After briefly recapitulating research results about the empathising-systemising (E-S) theory and motivation to learn science, the paper describes the science of empathy and then reflects on the opportunities and challenges of introducing empathy into science teaching. Many studies of effective science learning can be found that involve empathising, though this usually is not made explicit. Thus, bringing empathy into play sheds another light on successful science learning and helps in unfolding its full potential. Moreover, considerations about the role of values in science education entail the insight that, when it comes to complex socio-scientific issues, including empathy is not only useful, but actually vital. The concept of reflective equilibrium, taken from applied ethics, provides a framework for the consideration of both systematic and empathic aspects in science teaching. This undervalued approach promises to involve all students and is therefore a genuine science for all approach
United Kingdom: An example of the impact of high stakes accountability regimes on STEM education
In this chapter we focus on science, technology, engineering and mathematics (STEM) education in the United Kingdom. We examine government policy and describe various strategies and programmes that have been designed and implemented with a view to improving the system. The UK, and particularly England, provides a case study of high stakes accountability regimes. Root and branch reforms have seen major changes in curriculum and assessment at a number of levels as well as an attempt to impose a national pedagogic strategy
The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach
International audienceThe impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario). In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC) model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A) is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 ?eq l-1. These calculations assume that extremely low calcium leaching losses (9?27 ?eq l-1) from forest soils can be maintained without any decrease in forest productivity. Calcium concentrations in the three lakes have decreased by between ?10 and 25% over the past 20 years and calculations assume that calcium concentrations in lakes can fall to around 30% of their current values without any harmful effects on biota. Both these assumptions require urgent investigation. Keywords: acid deposition, calcium, critical loads, forests, harvesting, lakes</p
Shape-dependent Depinning of a Domain Wall by a Magnetic Field and a Spin-Polarized Current
The effect of sample shape on the depinning of the domain wall (DW) driven by
an applied magnetic field or a spin-polarized current is studied theoretically.
The shape effect resulting from the modulation of the sample width (geometric
pinning) can essentially affect the DW depinning. We found a good agreement
between the ratios of the critical values of the magnetic field and the
spin-polarized current predicted by the theory and measured in the experiment.Comment: 9 pages, 5 figure
“I want to do it all day!” – Students’ experiences of classroom movement integration
Whole-of-school physical activity programming is being advocated internationally, with movement integration in the classroom considered an effective method to increase physical activity throughout the school day. Students (N = 135) from two primary schools in the West of Ireland participated in this study. Data were collected using draw-and-write (N = 135) and focus group interviews (N = 24). Three themes were evident across data types and revealed that students thought the Moving to Learn Ireland active lessons were fun, that they learned academic content better, and the lessons contributed to their fitness development. In conclusion, children who participated in this study positively perceived movement integration lessons in their classrooms. The results of this study can inform future movement integration interventions
Patterns of gene expression in schistosomes: localization by whole mount in situ hybridization
rom the identification of genes to the characterization of their functions and interactions. Developmental biologists have long used whole mount in situ hybridization (WISH) to determine gene expression patterns, as a vital tool for formulating and testing hypotheses about function. This paper describes the application of WISH to the study of gene expression in larval and adult schistosomes. Fixed worms were permeablized by proteinase K treatment for hybridization with digoxygenin-labelled RNA probes, with binding being detected by alkaline phosphatase-coupled anti-digoxygenin antibodies, and BM Purple substrate. Discrete staining patterns for the transcripts of the molecules Sm29, cathepsin L, antigen 10.3 and chorion were observed in the tegument cell bodies, gut epithelium, oesophageal gland and vitelline lobules, respectively, of adult worms. Transcripts of the molecules SGTP4, GP18-22 and cathepsin L were localized to tegument cell bodies and embryonic gut, respectively, of lung schistosomula. We also showed that Fast Red TR fluorescent substrate can refine the pattern of localization permitting use of confocal microscopy. We believe that method of WISH will find broad application, in synergy with other emerging post-genomic techniques, such as RNA interference, to studies focused at increasing our molecular understanding of schistosomes
Temperature-(208-318 K) and pressure-(18-696Torr) dependent rate coefficients for the reaction between OH and HNO3
Abstract. Rate coefficients (k5) for the title reaction were ob- tained using pulsed laser photolytic generation of OH cou- pled to its detection by laser-induced fluorescence (PLP– LIF). More than 80 determinations of k5 were carried out in nitrogen or air bath gas at various temperatures and pres- sures. The accuracy of the rate coefficients obtained was en- hanced by in situ measurement of the concentrations of both HNO3 reactant and NO2 impurity. The rate coefficients show both temperature and pressure dependence with a rapid in- crease in k5 at low temperatures. The pressure dependence was weak at room temperature but increased significantly at low temperatures. The entire data set was combined with se- lected literature values of k5 and parameterised using a com- bination of pressure-dependent and -independent terms to give an expression that covers the relevant pressure and tem- perature range for the atmosphere. A global model, using the new parameterisation for k 5 rather than those presently ac- cepted, indicated small but significant latitude- and altitude- dependent changes in the HNO 3 / NO x ratio of between − 6 and + 6 %. Effective HNO 3 absorption cross sections (184.95 and 213.86 nm, units of cm 2 molecule − 1 ) were ob- tained as part of this work: σ 213 . 86 = 4.52 + 0 . 23 − 0 . 12 × 10 − 19 and σ 184 . 95 = 1.61 + 0 . 08 − 0 . 04 × 10 − 17
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