Mouthguards for contact sports: current state of use

Thesis (M.A.)--Boston UniversityTraumatic dental injury (TDI) is a public health problem that affects millions of individuals each year. Contact sports and sports-related activities such as boxing, basketball, and bicycling are the number one cause for TDI’s. The most common TDI’s resulting from sporting accidents are soft tissue laceration, tooth fracture, luxation and avulsion. Some individuals are more at risk than others in sustaining a TDI due to various predisposing factors. Individuals are at greater risk of dental trauma if they have protruding teeth, insufficient lip closure, and/or teeth that have received restorative dental treatment. Adolescents and teenagers are known to be most affected by TDI’s because they are the subset of the population most involved in contact sports and other physical activities. Mouthguards were developed to prevent the occurrence and severity of these dental injuries. There are three different types of mouthguards currently in use. They are the stock, mouth-formed, and custom-made mouthguards. Stock and mouth-formed mouthguards are the least recommended by dental professionals, yet in combination are worn the most because of their affordability and ease of use. Custom-made mouthguards are the most accepted mouthguards by the dental community because they are the most adapted to the particular individual, and are associated with the lowest number of TDI’s out of the three types of mouthguards. Users of mouthguards are nearly three times less likely to sustain a TDI while participating in a sport, compared to non-users. Unfortunately, many active individuals do not utilize mouthguards. Non-users of mouthguards associate wearing of mouthguards with undesirable effects, such as breathing difficulties and speech impairment. The side-effects of mouthguards can be so prevalent that they can potentially cause impairment in ones playing ability. In hopes of increasing the number of mouthguard users, researchers and manufactures have continually found new ways to eliminate the negative side-effects of mouthguards, while enhancing their protective function. Researchers have found mouthguards made from ethylene vinyl acetate (EVA) to have the lowest report of wearer opposition. EVA materials are soft and durable, but more importantly, can be tailored to satisfy the needs of the individual. Also, certain materials and designs can be incorporated into the EVA material to better the mouthguards protective function. For instance, past experiments have shown the placement of compliant materials, such as Sorbothane, in between two sheets of EVA material will significantly enhance the mouthguards protective capability. However, the joining of multiple materials may result in thicker and less comfortable mouthguards. More recent mouthguard trials have focused on limiting the thickness of mouthguards, while achieving the same level of protection seen in mouthguards made from multiple materials. Researchers have found the insertion of air cells within the EVA material to be useful technique in minimizing the overall thickness of mouthguards, while preserving the mouthguards protective function. In continuing to meet the high demands of athletes and active individuals, researchers and manufactures must develop newer mouthguards by exploring the effectiveness of other materials, as well as finding alternative methods in which mouthguards can be made

Gravitational partial-wave absorption from scattering amplitudes

We study gravitational absorption effects using effective on-shell scattering amplitudes. We develop an in-in probability-based framework involving plane- and partial-wave coherent states for the incoming wave to describe the interaction of the wave with a black hole or another compact object. We connect this framework to a simplified single-quantum analysis. The basic ingredients are mass-changing three-point amplitudes that model the leading absorption effects. As an application, we consider a non-spinning black hole that may start spinning as a consequence of the dynamics. The corresponding amplitudes are found to correspond to covariant spin-weighted spherical harmonics, the properties of which we formulate and make use of. We perform a matching calculation at the cross-section level to general-relativity results and derive the effective absorptive three-point couplings. They are found to behave as ${\cal O}(G^{s+1})$, where $s$ is the spin of the outgoing massive state.Comment: 33 pages + appendices + refs, 5 figure

The Impact of Integrating Computer Simulations On The Achievement of Grade 11 Emirati Students In Uniform Circular Motion

Education has been affected by the advancement of technology, especially computer software. This thesis focuses on the impact of computer simulations on students’ acquisition of Physics concepts related to the topic of Uniform Circular Motion. The main purpose of this thesis is to examine to what extent can computer simulations help students of grade 11 from Al Ain, United Arab Emirates (UAE), learn factual, conceptual and procedural knowledge related to Uniform Circular Motion. It also aims to investigate how simulations affect students of different abilities in terms of their achievement in Physics. A quazi- experimental method was used, where participants were divided into an experimental group and a control group. The experimental group was taught using computer simulations, and the control group was instructed with the help of real- life videos and animations. The main instrument was an achievement test administered before and after the intervention. The study showed a statistically significant advantage for the experimental group over the control group, especially in the procedural knowledge dimension. In addition, results showed that students of medium and low academic levels benefit from the simulations more than students of high level. Results drawn from this study provide valuable information on effective integration of technology in physics teaching, because it examines the impact of simulations on different knowledge dimensions, as well as their effect on students of different abilities. As a result, it encompasses a large spectrum of variables in terms of the effectiveness of simulations, giving room for further researches on technology integration in science education in the UAE and the Arab world context

Using Support Vector Machines and Bayesian Filtering for Classifying Agent Intentions at Road Intersections

Classifying other agents’ intentions is a very complex task but it can be very essential in assisting (autonomous or human) agents in navigating safely in dynamic and possibly hostile environments. This paper introduces a classification approach based on support vector machines and Bayesian filtering (SVM-BF). It then applies it to a road intersection problem to assist a vehicle in detecting the intention of an approaching suspicious vehicle. The SVM-BF approach achieved very promising results.Ford Motor Company, Le Fonds Quebecois de la Recherche sur la Nature et les Technologies (FQRNT

Searching for Kerr in the 2PM amplitude

The classical scattering of spinning objects is well described by the spinor-helicity formalism for heavy particles. Using these variables, we derive spurious-pole-free, all-spin opposite-helicity Compton amplitudes (factorizing on physical poles to the minimal, all-spin three-point amplitudes of ref. \cite{Arkani-Hamed:2017jhn}) in the classical limit for QED, QCD, and gravity. The cured amplitudes are subject to deformations by contact terms, the vast majority of whose contributions we can fix by imposing a relation between spin structures -- motivated by lower spin multipoles of black hole scattering -- at the second post-Minkowskian (2PM) order. For QED and gravity, this leaves a modest number of unfixed coefficients parametrizing contact-term deformations, while the QCD amplitude is uniquely determined. Our gravitational Compton amplitude allows us to push the state-of-the-art of spinning-2PM scattering to any order in the spin vectors of both objects; we present results here and in the auxiliary file \texttt{2PMSpin8Aux.nb} up to eighth order in the spin vectors. Interestingly, despite leftover coefficients in the Compton amplitude, imposing the aforementioned relation between spin structures uniquely fixes some higher-spin parts of the 2PM amplitude.Comment: 23 pages, 2 figures, 2 appendices. Full 2PM amplitude up to eighth order in spin in Mathematica attachment. v2: fixed typos, updated reference