4,490 research outputs found
A cross-cultural study of suicide in twenty-three pre-literate societies
Thesis (M.S.)--Boston Universit
Stable Unitary Integrators for the Numerical Implementation of Continuous Unitary Transformations
The technique of continuous unitary transformations has recently been used to
provide physical insight into a diverse array of quantum mechanical systems.
However, the question of how to best numerically implement the flow equations
has received little attention. The most immediately apparent approach, using
standard Runge-Kutta numerical integration algorithms, suffers from both severe
inefficiency due to stiffness and the loss of unitarity. After reviewing the
formalism of continuous unitary transformations and Wegner's original choice
for the infinitesimal generator of the flow, we present a number of approaches
to resolving these issues including a choice of generator which induces what we
call the "uniform tangent decay flow" and three numerical integrators
specifically designed to perform continuous unitary transformations efficiently
while preserving the unitarity of flow. We conclude by applying one of the flow
algorithms to a simple calculation that visually demonstrates the many-body
localization transition.Comment: 13 pages, 4 figures, Comments welcom
Automated precision passing system
Athletes are always seeking ways to improve their performance. Down time and a lack of capable throwers prevent athletic receivers from practicing their skills. We hope to aid athletes in receiving drills within their respective sports and increase practice efficiency. In order to achieve this, the machine has one major axis of rotation driven by a motor. This enables it to adjust where the ball is being thrown. Using an Arduino Uno coupled with a Roboteq AX1500 motor driver, the Automated Precision Passing System is able to throw a ball to a specified point in space by adjusting both the azimuth and ball-throwing motor speed. Our testing shows that our prototype has the ability to position itself in three different orientations as well as adjust the launch motor speed, but we were unable to launch the ball the original distance that we desired. From this project, we gained valuable knowledge in the areas of machine design, control systems, and project management. In order to continue the project and create a functional consumer product there are several improvements that need to be made to the system. The Automated Precision Passing System needs to be more rigid, have more power, and include more throwing positions
Multiple-scale structures: from Faraday waves to soft-matter quasicrystals
For many years, quasicrystals were observed only as solid-state metallic
alloys, yet current research is now actively exploring their formation in a
variety of soft materials, including systems of macromolecules, nanoparticles
and colloids. Much effort is being invested in understanding the thermodynamic
properties of these soft-matter quasicrystals in order to predict and possibly
control the structures that form, and hopefully to shed light on the broader
yet unresolved general questions of quasicrystal formation and stability.
Moreover, the ability to control the self-assembly of soft quasicrystals may
contribute to the development of novel photonic or other applications based on
self-assembled metamaterials. Here a path is followed, leading to quantitative
stability predictions, that starts with a model developed two decades ago to
treat the formation of multiple-scale quasiperiodic Faraday waves (standing
wave patterns in vibrated fluid surfaces) and which was later mapped onto
systems of soft particles, interacting via multiple-scale pair potentials. The
article reviews, and substantially expands, the quantitative predictions of
these models, while correcting a few discrepancies in earlier calculations, and
presents new analytical methods for treating the models. In so doing, a number
of new stable quasicrystalline structures with octagonal, octadecagonal and
higher-order symmetries, some of which may, it is hoped, be observed in future
experiments.Comment: 22 pages, 22 figures, 1 table. Comments welcom
The Key To Solving Agency Lock-In: Prepublication Regulatory Discussions (Pre Reg)
Most legally binding administrative rules emerge from the notice-and-comment process, which explicitly requires the agency to consider input from the general public. However, by the time the opportunity for public input occurs, the agency is already substantially locked into its chosen approach and cannot act on new information in the comments. This is true even though its chosen approach was decided upon with input from only those the agency routinely deals with. This process entrenches already established interests and prevents those without existing agency connections from meaningfully contributing earlier in the process.
This problem could be solved by holding public discussions online before the publication of the proposed rule and therefore before the agency is locked in. Employing modem Internet guidelines would ensure that all those who wish to participate can, while preventing bad actors from disrupting the purpose and atmosphere of the discussion. This approach would combine the benefits of current alternative agency practices while avoiding the drawbacks that frequently prevent their use. Agencies that are expected to work on behalf of the public should likewise have an effective method to accept input from that same public before becoming locked into a choice of action
Administrative Compensation for Military Harassment and Sexual Assault: A Win-Win for Victims and the Military
Last year, none of the more than 20,000 victims of sexual assault in the military were entitled to any compensation. Nor were the hundreds of thousands of service members subjected to racial and sexual harassment compensated in any way. Advocates have fought for decades to overturn the Feres doctrine to allow victims to sue the government in court. The military has countered that it must retain control over all issues involving discipline. However, the military lacks the information necessary to be able to take effective action against those who harm others because many victims are afraid to come forward for fear of retaliation. This Article offers a way to solve both problems. It proposes creating an administrative process to compensate victims for the harm they endured while simultaneously providing an incentive for them to report the initial crime, as well as any retaliation they experience, thereby finally providing the military with the critical information it needs to act, which it is unable to obtain any other way
Reassessing Administrative Finality: The Importance of New Evidence and Changed Circumstances
Administrative finality of agency action is generally thought of as a method of avoiding premature judicial review—a claim that the review is too early. But it is also used to prevent judicial review by claiming that the review has now come too late. There are two primary exceptions to this prohibition: new evidence and changed circumstances. However, courts and agencies are reluctant to permit challengers to use these exceptions as often as should be statutorily allowed, an area that scholarship has been neglected.
This Article fills the gap by exploring this aspect of administrative finality, looking at the important government interests the doctrine safeguards, as well as both the individual and government interests counseling against finality in these changed circumstances. It reaches the conclusion that the doctrine is being applied too strictly, examining recent cases involving both disability and immigration where it has prevented proper review of the agency decision at issue
Using Professionally Trained Interpreters to Increase Patient/Provider Satisfaction: Does It Work?
Examines the need for trained medical interpreters by comparing the satisfaction of emergency room patients, doctors, and triage and discharge nurses when provided with interpreters and when provided only with telephone language lines or ad hoc services
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