Magnetoelastic Effects in Iron Telluride

Iron telluride doped lightly with selenium is known to undergo a first order magneto-structural transition before turning superconducting at higher doping. We study the effects of magneto-elastic couplings on this transition using symmetry considerations. We find that the magnetic order parameters are coupled to the uniform monoclinic strain of the unit cell with one iron per cell, as well as to the phonons at high symmetry points of the Brillouin zone. In the magnetic phase the former gives rise to monoclinic distortion while the latter induces dimerization of the ferromagnetic iron chains due to alternate lengthening and shortening of the nearest-neighbour iron-iron bonds. We compare this system with the iron arsenides and propose a microscopic magneto-elastic Hamiltonian which is relevant for all the iron based superconductors. We argue that this describes electron-lattice coupling in a system where electron-electron interaction is crucial.Comment: 5 pages, 2 figure

Magneto-elastic quantum fluctuations and phase transitions in the iron superconductors

We examine the relevance of magneto-elastic coupling to describe the complex magnetic and structural behaviour of the different classes of the iron superconductors. We model the system as a two-dimensional metal whose magnetic excitations interact with the distortions of the underlying square lattice. Going beyond mean field we find that quantum fluctuation effects can explain two unusual features of these materials that have attracted considerable attention. First, why iron telluride orders magnetically at a non-nesting wave-vector $(\pi/2, \pi/2)$ and not at the nesting wave-vector $(\pi, 0)$ as in the iron arsenides, even though the nominal band structures of both these systems are similar. And second, why the $(\pi, 0)$ magnetic transition in the iron arsenides is often preceded by an orthorhombic structural transition. These are robust properties of the model, independent of microscopic details, and they emphasize the importance of the magneto-elastic interaction.Comment: 4 pages, 3 figures; minor change

Ultra high bypass Nacelle aerodynamics inlet flow-through high angle of attack distortion test

A flow-through inlet test program was conducted to evaluate inlet test methods and determine the impact of the fan on inlet separation when operating at large angles of attack. A total of 16 model configurations of approximately 1/6 scale were tested. A comparison of these flow-through results with powered data indicates the presence of the fan increased separation operation 3 degrees to 4 degrees over the flow through inlet. Rods and screens located at the fan face station, that redistribute the flow, achieved simulation of the powered-fan results for separation angle of attack. Concepts to reduce inlet distortion and increase angle of attack capability were also evaluated. Vortex generators located on the inlet surface increased inlet angle of attack capability up to 2 degrees and reduced inlet distortion in the separated region. Finally, a method of simulating the fan/inlet aerodynamic interaction using blockage sizing method has been defined. With this method, a static blockage device used with a flow-through model will approximate the same inlet onset of separation angle of attack and distortion pattern that would be obtained with an inlet model containing a powered fan

Christian civilization in Ireland

Thesis (M.A.)--Boston University This item was digitized by the Internet Archive

America’s Two Pastimes: Baseball and Constitutional Law; Review of Adrian Vermeule, \u3ci\u3eCommon Good Constitutionalism\u3ci\u3e

For the last 50 years, the two prevailing constitutional interpretation methodologies have been Originalism and Living Constitutionalism. The former treats the Constitution almost like a contract and demands that interpreters focus on the ordinary contemporary understanding its terms would have received when they became law. The latter treats the Constitution as a charter for the structure of a new government that would survive and mature as needed to protect both the nation and its people as new threats to government and civil liberties arise. Professor Adrian Vermeule’s book Common Good Constitutionalism offers a new approach to constitutional interpretation, one that gives far greater prominence to the need to protect and advance the good of the nation as a whole than either of the other two theories would require. His theoretical justification for the new approach stems from the classical or natural law principle that a nation may demand that its interests outweigh those of any individual or group. He criticizes Originalism as a morally sterile, positivistic approach to legal interpretation, and Living Constitutionalism as concerned only with the interests of individuals and groups without regard for those of the polity. Professor Vermeule, however, does not give sufficient weight to what the Constitution did—viz., create a democratic republic whose elected representatives would make moral judgments—than what a court may do when reviewing their work. He also fails to address a goodly number of issues that any new theory of constitutional interpretation must address to serve the role that he posits for Common Good Constitutionalism. He does not give adequate weight to the rationale endorsed in Marbury v. Madison that it is the text that governs, not background principles, however weighty they might be. He does not address how his theory affects antidiscrimination law, the application of the Bill of Rights to the states, or principles of stare decisis. In sum, Common Good Constitutionalism, while valuable, is better seen as a codicil to Originalism (to which it is closer than Living Constitutionalism) than as an entirely new, different will

Talent identification and recruitment in youth soccer: Recruiter’s perceptions of the key attributes for player recruitment

Using the modified Delphi method, we aimed to understand the attributes youth coaches and recruiters perceive as important when identifying skilled youth performance at the entry level of representative soccer in Australia (i.e., Under 13 years). Furthermore, we also aimed to describe the current methods youth coaches and recruiters use to assess and identify these attributes in youth players. Australian regional youth technical directors and coaches (n = 20) completed a three stage process, including an initial interview and two subsequent questionnaires, whereby attributes and qualities associated with talent identification were rated and justified according to the importance for youth player performance and talent identification. Results indicate a hierarchy of attributes recruiters perceive as important for Under 13 soccer performance, including technical (i.e., first touch, striking the ball, one-versus-one ability, and technical ability under pressure), tactical (i.e., decision-making ability) and psychological attributes (i.e., coachability and positive attitude). In addition, the findings indicated attributes and qualities not emphasised within the talent identification process including, physiological, anthropometrical, sociological and several psychological attributes. It is suggested talent recruiters apply a holistic multidisciplinary approach to talent identification, with the current findings potentially providing initial evidence to suggest recruiters do consider numerous attributes when selecting and identifying youth players