345 research outputs found
Heater Control for Thermionic Power Generation
The purpose of this report is to detail the conceptualization, analysis, budget, manufacturing, and assembly the heater for a thermionic energy converter for portable energy generation. This proof of concept will be created to provide a full thermionic energy converter with a reliable and satisfactory heater than can be used in future systems. The report highlights the feasibility and realities in the design and fabrication of the system
Higgs-photon resonances
We study models that produce a Higgs boson plus photon ()
resonance at the LHC. When the resonance is a boson, decays to occur at one loop. If the boson couples at tree-level to quarks,
then the branching fraction is typically of order or
smaller. Nevertheless, there are models that would allow the observation of at TeV with a cross section times branching
fraction larger than 1 fb for a mass in the 200--450 GeV range, and larger
than 0.1 fb for a mass up to 800 GeV. The 1-loop decay of the into lepton
pairs competes with , even if the couplings to leptons vanish
at tree level. We also present a model in which a boson decays into a
Higgs boson and a pair of collimated photons, mimicking an
resonance. In this model, the resonance search would be the
discovery mode for a as heavy as 2 TeV. When the resonance is a scalar,
although decay to is forbidden by angular momentum conservation,
the plus collimated photons channel is allowed. We comment on prospects
of observing an resonance through different Higgs decays, on
constraints from related searches, and on models where is replaced by a
nonstandard Higgs boson.Comment: 22 page
Constitutional Law - Right to Travel
The United States Supreme Court has held that state residency requirements for eligibility under federal welfare assistance programs are unconstitutional because they restrict the right to travel.
Shapiro v. Thompson, 89 S. Ct. 1322 (1969)
Intravascular ultrasound: a technique in evolution: methodological considerations
As the title of the thesis suggests, intravascular ultrasound has been, and continues to be, an imaging technique that is in active evolution. Image quality has improved dramatically from the crude, low resolution 'black and white' images of the first generation of intravascular ultrasound scanners and transducers are now small enough to image most arteries before intervention. Although intravascular ultrasound is increasingly seen as the most informative method of assessing the coronary arteries, there are outstanding problems that must be addressed and overcome before its full potential can be achieved.The aim of this thesis is to examine a number of these methodological shortcomings of intravascular ultrasound so that appropriate solutions can be found.After a general overview, provided in Chapter 1, the reproducibility of intravascular ultrasound quantitation is assessed in Chapter 2. For reasons elaborated above, ultrasound is seen as the best technique to study the acute and long term outcome of coronary interventions and the effect of plaque modifying agents. Without detailed data concerning its reproducibility, such studies are uninterpretable.Chapter 3 deals with the impact of catheter malfunction on the geometric integrity of intravascular ultrasound images. At present, the mechanical ultrasound devices are the most widely used systems. All mechanical systems are potentially subject to the problem of non -uniform rotation of the transducer, and to date its impact has been poorly characterised.The difficulty encountered in discriminating unstable coronary lesions is examined in Chapter 4. There is a widely held view that acute coronary lesions cannot be discriminated using intravascular ultrasound. Specific echographic markers are described that are found in the majority of unstable lesions. Close scrutiny of grey scale images allows identification of acute lesions and may allow discrimination of thrombus from underlying atheromatous plaque.In the last two chapters, methodological issues relating to the clinical application of intravascular ultrasound in guiding coronary stenting are explored. In chapter 5, the findings of an observational study confirm the potential of intravascular ultrasound to provide additional information in cases in which favourable angiographic appearances have been achieved. However, the choice of one particular 'expansion index' over another is seen to impact significantly on the proportion of lesions that are judged to be successful. Before ultrasound guidance based on the attainment of specific quantitative expansion criteria be advocated as a widely applied technique, the reproducibility of reference segment measurements must be known. This issue is studied in chapter 6.Separate studies are described in each of the data chapters. A similar layout is employed in each, consisting of the study aims, methods, findings, discussion and conclusion. At the risk of introducing a degree of repetition in the methods sections of each chapter, the ultrasound examination and image interpretation protocol are elaborated in each case, as important differences exist between the studies
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The nanny in the United States : a search for professional recognition.
The study investigated the perceptions and practices of nanny training school officials, employed nannies and nanny employers in New England, New York, and New Jersey. It was specifically focused on whether the training received is sufficient for the jobs the nannies perform and the responsibilities they are given. Additionally, it examined the issue of professionalism with the nanny industry. The study was based upon an ex post facto research methodology and involved both quantitative and qualitative method of inquiry. Data collection was accomplished through mailed questionnaires and in-person interviews. As a result of the research, it was discovered that: (1) While most nanny schools are affiliated with community colleges, no degrees nor college credits are awarded. (2) There was a major discrepancy between the number of classroom hours said to be required for graduation and those which could be accounted for by nanny school officials. (3) Unsubstantiated classroom hours accounted for between 17% and 69% of the total required hours. (4) While nanny schools profess the demand to supply ratio is 100 to 1, only 65% of nanny school graduates are currently employed. (5) Employed nannies disagree with nanny school officials on whether special skills are needed to perform their jobs. (6) Most employers are not seeking professionals when hiring nannies. They would prefer to train nannies according to their own expectations. (7) The most crucial problem to be overcome in a nanny-employer relationship is that of privacy, according to both employed nannies and nanny employers
Temporal-Difference Learning to Assist Human Decision Making during the Control of an Artificial Limb
In this work we explore the use of reinforcement learning (RL) to help with
human decision making, combining state-of-the-art RL algorithms with an
application to prosthetics. Managing human-machine interaction is a problem of
considerable scope, and the simplification of human-robot interfaces is
especially important in the domains of biomedical technology and rehabilitation
medicine. For example, amputees who control artificial limbs are often required
to quickly switch between a number of control actions or modes of operation in
order to operate their devices. We suggest that by learning to anticipate
(predict) a user's behaviour, artificial limbs could take on an active role in
a human's control decisions so as to reduce the burden on their users.
Recently, we showed that RL in the form of general value functions (GVFs) could
be used to accurately detect a user's control intent prior to their explicit
control choices. In the present work, we explore the use of temporal-difference
learning and GVFs to predict when users will switch their control influence
between the different motor functions of a robot arm. Experiments were
performed using a multi-function robot arm that was controlled by muscle
signals from a user's body (similar to conventional artificial limb control).
Our approach was able to acquire and maintain forecasts about a user's
switching decisions in real time. It also provides an intuitive and reward-free
way for users to correct or reinforce the decisions made by the machine
learning system. We expect that when a system is certain enough about its
predictions, it can begin to take over switching decisions from the user to
streamline control and potentially decrease the time and effort needed to
complete tasks. This preliminary study therefore suggests a way to naturally
integrate human- and machine-based decision making systems.Comment: 5 pages, 4 figures, This version to appear at The 1st
Multidisciplinary Conference on Reinforcement Learning and Decision Making,
Princeton, NJ, USA, Oct. 25-27, 201
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