Middle school students' perceptions of engineering

This paper focuses on implementing engineering education in middle school classrooms (grade levels 7-9). One of the aims of the study was to foster students’ and teachers’ knowledge and understanding of engineering in society. Given the increasing importance of engineering in shaping our daily lives, it is imperative that we foster in students an interest and drive to participate in engineering education, increase their awareness of engineering as a career path, and inform them of the links between engineering and the enabling subjects, mathematics, science, and technology. Data for the study are drawn from five classes across three schools. Grade 7 students’ responded to initial whole class discussions on what is an engineer, what is engineering, what characteristics engineers require, engineers (family/friends) that they know, and subjects that may facilitate an engineering career. Students generally viewed engineers as creative, future-oriented, and artistic problem finders and solvers; planners and designers; “seekers” and inventors; and builders of constructions. Students also viewed engineers as adventurous, decisive, community-minded, reliable, and “smart.” In addition to a range of mathematics and science topics, students identified business studies, ICT, graphics, art, and history as facilitating careers in engineering. Although students displayed a broadened awareness of engineering than the existing research suggests, there was limited knowledge of various engineering fields and a strong perception of engineering as large construction

Seronegative spondyloarthropathies : a review : part I: classification and differential diagnosis

The seronegative spondyloarthropathies comprise a group of non-rheumatoid disorders with similar clinical, laboratory and genetic features. Recognition of new clinical features has supported the notion that they all form part of a clinical spectrum. These features and the classification of the seronegative spondyloarthropathies are discussed in the review.peer-reviewe

Seronegative spondyloarthropathies : a review : part II: genetics and pathogenesis

In none of the spondyloarthropathies is the pathogenesis well understood. Much of the investigation into the aetio-pathogenesis of these diseases has focused on the association with HLA-B27 and the known triggering potential of certain infectious agents. In this article the author describes that the HLA linked genes which is subdivided into three groups, class I, class II and class III, which are structurally and functionally distinct from each other.peer-reviewe

Method of vibration isolating an aircraft engine

A method for coupling an engine to a support frame for mounting to a fuselage of an aircraft using a three point vibration isolating mounting system in which the load reactive forces at each mounting point are statically and dynamically determined. A first vibration isolating mount pivotably couples a first end of an elongated support beam to a stator portion of an engine with the pivoting action of the vibration mount being oriented such that it is pivotable about a line parallel to a center line of the engine. An aft end of the supporting frame is coupled to the engine through an additional pair of vibration isolating mounts with the mounts being oriented such that they are pivotable about a circumference of the engine. The aft mounts are symmetrically spaced to each side of the supporting frame by 45 degrees. The relative orientation between the front mount and the pair of rear mounts is such that only the rear mounts provide load reactive forces parallel to the engine center line, in support of the engine to the aircraft against thrust forces. The forward mount is oriented so as to provide only radial forces to the engine and some lifting forces to maintain the engine in position adjacent a fuselage. Since each mount is connected to provide specific forces to support the engine, forces required of each mount are statically and dynamically determinable

Development of Needle Trap Technology for On-Site Determinations: Active and Passive Sampling

This study presents a thorough evaluation of new prototypes of extended tip needle trap devices (NT), as well as their application to in situ sampling of biological emissions and active/passive on-site sampling of indoor air. A new NT prototype was constructed with a side hole above the sorbent and an extended tip that fits inside the restriction of the narrow neck liner to increase desorption efficiency.New prototype needles were initially packed with divinylbenzene particles at SGE Analytical Science for the purpose of studying biogenic emissions of pine trees. Prior to their final application, they were evaluated in terms of robustness after multiple use (n ˃ 10), as well as amount extracted of volatile organic compounds (VOCs). An ANOVA test for all the probes showed that at a 95 % level of confidence, there were not statistical differences observed among the 9 NTs tested. In addition, the needles were also packed in laboratory with synthesized highly cross linked PDMS as a frit to immobilize carboxen (Car) particles for spot sampling. For passive sampling, the needles were packed with Car particles embedded in PDMS in order to simplify calculations in passive mode. The use of NTs as spot samplers, as well as a passive sampler under controlled conditions in the laboratoryyielded a relative standard deviation of less than 15 %. Finally, a new, reusable and readily deployable pen-like diffusive sampler for needle traps (PDS-NT) was built and tested. Application of the PDS-NT in combination with NT-spot sampling towards the analysis of indoor air in a polymer synthesis laboratory showed good agreement between both techniques for the analyte studied, yielding averages of 0.03 ng/mL and 0.025 ng/mL of toluene, respectively.NSERC Industrial Research Chair || NSERC IRCPJ/184412-10 05016

Generosity and Political Preferences

We test whether generosity is related to political preferences and partisanship in Canada, Sweden, the United Kingdom and the United States using incentivized dictator games. The total sample consists of more than 5,000 respondents. We document that support for social spending and redistribution is positively correlated with generosity in all four countries. Further, we show that donors are more generous towards co-partisans in all countries, and that this effect is stronger among supporters of left-wing political parties. All results are robust to the inclusion to an extensive set of control variables, including income and education

The 1 : √2 mode interaction and heteroclinic networks in Boussinesq convection

Copyright © 2007 Elsevier. NOTICE: This is the author’s version of a work accepted for publication by Elsevier. Changes resulting from the publishing process, including peer review, editing, corrections, structural formatting and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Physica D, Vol 234, Issue 1, October 2007, DOI: 10.1016/j.physd.2007.06.024Methods of equivariant bifurcation theory are applied to Boussinesq convection in a plane layer with stress-free horizontal boundaries and an imposed square lattice periodicity in the horizontal directions. We consider the problem near the onset of instability of the uniform conducting state where spatial roll patterns with two different wavelengths in the ratio 1 : √2 become simultaneously unstable at a mode interaction. Centre manifold reduction yields a normal form on C4 with very rich dynamical behavior. For a fixed Prandtl number P the mode interaction occurs at an isolated point in the parameter plane (R,L) (where R is the Rayleigh number and L the length of the horizontal periodicities) and acts as an organizing center for many nearby bifurcations. The normal form predicts appearance of many steady states and travelling waves, which are classified by their symmetries. It also predicts the appearance of robust heteroclinic networks involving steady states with several different symmetries, and robust attractors of generalized heteroclinic type that include connections from equilibria to subcycles. This is the first example of a heteroclinic network in a fluid dynamical system that has ‘depth’ greater than one. The normal form dynamics is in good correspondence (both quantitatively and qualitatively) with direct numerical simulations of the full convection equations