Analogue Wormholes and Black Hole LASER Effect in Hydrodynamics

We numerically study water wave packets on a spatially varying counter-current in the presence of surface tension. Depending on the details of the velocity profile, we show that traversable and bi-directional analogue wormholes exist in fluid mechanics. The limitations on traversability of wormholes in general relativity are absent here because of the dispersion of water waves and the ability to form flow profiles that are not solutions of Einstein's equations. We observe that negative energy can be trapped between analogue horizons forming a LASER-like cavity. Six horizons are involved in the trapping cavity because of the existence of two dispersive scales, in contrast to previous treatments which considered two horizons and one dispersive scale.Comment: 11 page

Alien Registration- St. Germain, Thomas (Biddeford, York County)

https://digitalmaine.com/alien_docs/5104/thumbnail.jp

Applying Systems Theory as a Lens on Teacher and Student Perceptions of Assessment and Feedback in an Intensive English Program

The goal of this project was to apply systems theory, or more generally, systems thinking as a lens on the perceptions of teachers, students, and administrators who work together at an intensive English program (IEP). This goal necessitated a two-part project: a review of pertinent literature on systems theory and a limited qualitative study situated at the IEP. Sixteen participants, including seven teachers (more than half of the current faculty), two teacher/administrators, and seven students from different levels within the program, were invited to participate. The primary focus of the study was on participants’ awareness of and attitudes about two particular practices that are integral to the functioning of the school: assessment and feedback. In-depth interviews that centered on these two practices were utilized to gather the necessary qualitative data. This data was then analyzed to reveal topics and issues that were perceived by the participants to be of significance. Throughout the planning, execution, and analysis stages, the discipline of mental models served as a guiding principle. More generally, systems theory provided both a unique perspective and specific concepts that helped facilitate new, broadened understandings of the complex system known as the language school

Hawking tunneling and boomerang behaviour of massive particles with E < m

Copyright © 2012 American Institute of PhysicsTowards New Paradigms: Proceeding of the Spanish Relativity Meeting 2011 (ERE2011), 29 August–2 September 2011, Madrid, SpainMassive particles are radiated from black holes through the Hawking mechanism together with the more familiar radiation of massless particles. For E ≥ m, the emission rate is identical to the massless case. But E < m particles can also tunnel across the horizon. A study of the dispersion relation and wave packet simulations show that their classical trajectory is similar to that of a boomerang. The tunneling formalism is used to calculate the probability for detecting such E < m particles, for a Schwarzschild black hole of astrophysical size or in an analogue gravity experiment, as a function of the distance from the horizon and the energy of the particle

A Racist Little Hat: The MSG Debate and American Culture

Stop for a moment and ask yourself what you know about monosodium glutamate. If you’re anything like most Americans, your thoughts on the subject are probably simple: MSG is an artificial flavoring most often used with Chinese food, which should be avoided because it’s bad for you and gives you headaches. If this is your thinking, you’re not alone. For the past fifty years, this has been the conventional American understanding of MSG. But times change. Recently, a vocal movement has sprung up that advocates for an end to the stigma surrounding MSG, as detailed in a Buzzfeed article by John Mahoney titled, “The Notorious MSG’s Unlikely Formula For Success.” Mahoney suggests that a new cultural context is emerging, spearheaded by a group of celebrity chefs who take the iconoclastic position that we should reintroduce MSG to our palates. They argue that beyond the merits of its delicious savory flavor, referred to as “umami,” society’s trepidations about the ingredient are based on research born out of stark racism and bad science which have perpetuated a myth about MSG’s toxicity [1]. But the old guard isn’t going quietly, and just as vocal as the pro-MSG camp are those who fear a change to the status quo

Engineering the Surface Chemistry and Surface Conditions to Optimize the Heat Removal Rate of Various Surfaces

As the demand for more powerful and smaller electronics rise, the need for creative cooling solutions to prevent burnout becomes increasingly paramount. In response to recent cooling needs, new cooling techniques, such as jet impingement cooling, spray cooling, and heat pipes, have risen in popularity for their simple design and efficiency in thermal transport. This interest has risen in both industry and academia, where research has been conducted to optimize the heat transfer performance for these systems and how these systems can be implemented in new technologies. One method that has risen in interest is affecting the surface, through physical and chemical treatments, and how these different treatments can enhance the heat removal rate for different systems. This dissertation presents two main regions of research that, when combined, can enhance understanding of cooling rates for different surface treatments. The first region is utilizing time domain thermoreflectance (TDTR) to measure the heat transfer coefficients in a microchannel experiencing jet impingement cooling. This current study presents the findings of experiments that measure the heat transfer coefficients on surfaces exposed to hot-spot heating and cooled using water jet impingement at Reynolds numbers up to 6432. The heat transfer coefficients were found using TDTR with a water jet on a fused silica (FS) glass substrate coated with a thin-film Hafnium-alloy (Hf). The heat transfer coefficient data are based on a local, micron-sized hot-spot region (generated by the TDTR pump laser) that is translated at different locations relative to the stagnation point. The study shows that at different microchannel regions (relative to the stagnation point) and for different Reynolds numbers for the jet that the TDTR method can detect changes in the heat transfer coefficient. Along with a novel method to measure the heat transfer coefficients using TDTR, several studies on different surface conditions are presented in the dissertation. Physical changes in wetting performance is analyzed through soft wetting materials and the impact the stiffness has on the hemwicking performance. Through a novel, in house stamping apparatus, polydimethylsiloxane (PDMS) samples were created of varing stiffness of 0.338 MPa to 1.98 MPa. Through analyzing the hemiwicking velocity, hemiwicking diffusion, and initial hemiwicking wicking velocity of ethanol, isopropyl alcohol, and isooctane, it was observed that the stiffness of soft materials can play a significant impact on the overall wicking performance. Furthermore, a deformation model is presented based on pillar deformations observed with PDMS/ExoFlex hybrid samples as the working fluids evaporated from the wicking arrays. The chemical impact on the overall wetting performance is also analyzed and presented in this dissertation. Two main methods were implemented to track the changes in wetting through surface chemistry; through the application of a polyvinyl alcohol (PVA) self-assembled monolayer (SAM) and applying a spiropyran (SPCOOH) to a microstructured gold surface. The changes in hemiwicking velocity and meniscus extension with the PVA SAM displayed an important aspect of chemical interactions with respect to hemiwicking performance, which affects the heat transfer performance of a microstructured surface. The SPCOOH studies revealed a change in wetting behavior which further emphasized the importance of intermolecular interaction on wetting performance, but also revealed a controlling aspect the PVA SAM experiments did not exhibit. Along with these studies, a preliminary study of controlling the intermolecular interactions of metamaterials through strain to change the surface wetting is presented in this dissertation. Through the use of a simple, uni-axial strain instrument, different metamaterials composed of hafnium dioxide, titanium nitride, and tungsten deposited on Kapton tape were subjected to strains up to 8%. While under strain, significant changes in the advancing, receding, and equilibrium contact angle were observed for both polar and non polar fluids on the surface. These changes are attributed through changes in the intermolecular forces and verified through changes in the reflectivity while strain is applied to the metamaterials

Hawking radiation and the boomerang behaviour of massive modes near a horizon

Copyright © 2011 American Physical SocietyWe discuss the behaviour of massive modes near a horizon based on a study of the dispersion relation and wave packet simulations of the Klein-Gordon equation. We point out an apparent paradox between two (in principle equivalent) pictures of black hole evaporation through Hawking radiation. In the picture in which the evaporation is due to the emission of positive-energy modes, one immediately obtains a threshold for the emission of massive particles. In the picture in which the evaporation is due to the absorption of negative-energy modes, such a threshold apparently does not exist. We resolve this paradox by tracing the evolution of the positive-energy massive modes with an energy below the threshold. These are seen to be emitted and move away from the black hole horizon, but they bounce back at a "red horizon" and are re-absorbed by the black hole, thus compensating exactly for the difference between the two pictures. For astrophysical black holes, the consequences are curious but do not affect the terrestrial constraints on observing Hawking radiation. For analogue gravity systems with massive modes, however, the consequences are crucial and rather surprising

La politique de la danse contemporaine en France : une construction conjointe des pouvoirs publics et des lieux de programmation

La politique de soutien à la création chorégraphique contemporaine, initiée dans les années 1970 puis poursuivie dans les années 1980 et 1990 avec des moyens financiers considérablement accrus, débouche sur la constitution d’un monde artistique distinct de celui de la danse classique. Cependant, les compagnies ne disposent pas de salles de spectacles et leurs pièces sont principalement programmées dans des théâtres ou festivals eux-mêmes subventionnés, qui leur apportent des ressources en achetant des représentations ou en s’engageant financièrement en amont de la création (coproduction). Dans ce texte, la dénomination de « marché subventionné » désigne ce système d’économie mixte, conjuguant les décisions d’allocations de subventions publiques et le jeu relativement libre du marché intermédiaire de la diffusion, qui se construit progressivement à partir des années 1970. L’analyse du fonctionnement de ce marché subventionné fait apparaître un déséquilibre structurel lié au décalage entre le nombre de spectacles produits chaque année et les débouchés offerts par les réseaux de diffusion. Dans ce contexte, l’élargissement du public constitue un enjeu essentiel pour l’avenir de ce courant artistique en France.The policy of aid for contemporary dance, initiated in the 1970s, then continued in the 1980s and 1990s, with considerably higher financial means, culminated in the constitution of an artistic world distinct from that of classical dance. However, companies did not have venues at their disposal, and their pieces were predominantly programmed in theatres and festivals which were themselves subsidized, and which brought them resources in buying representations or in committing themselves to coproduction. The denomination “subsidized market” means this system of mixed economy, combining decisions on the allocations of public subsidies and the relatively free play of intermediary distribution markets, which were forming progressively from the 1970s. The analysis of the functioning of this subsidized market gendered the appearance of a structured imbalance linked to a gap between the number of performances produced annually and the outlets offered by the distribution networks. In this context, the enlarging of the population constituted an essential stake for the future of this artistic movement in France

Avant-propos

Jusqu’aux années 1960 en France, la danse classique jouit d’un monopole en termes de légitimité artistique et de financements publics. L’aide de l’État se concentre sur l’Opéra de Paris et il n’apporte qu’une contribution limitée à l’activité des autres troupes de ballet intégrées dans les maisons d’opéras municipales. Après l’apparition triomphale d’Isadora Duncan, la danseuse aux pieds nus, c’est surtout l’héritage des Ballets russes qui incarne la modernité et l’innovation artistique dans ..