Stability characterization of advanced injectors, design guide. Volume 2 - Operation of the computer program, Phase 3 Final report

Computerized stability design of time lag combustion system for liquid propellant rocket engin

Correlated charge polarization in a chain of coupled quantum dots

Coherent charge transfer in a linear array of tunnel-coupled quantum dots, electrostatically coupled to external gates, is investigated using the Bethe ansatz for a symmetrically biased Hubbard chain. Charge polarization in this correlated system is shown to proceed via two distinct processes: formation of bound states in the metallic phase, and charge transfer processes corresponding to a superposition of antibound states at opposite ends of the chain in the Mott-insulating phase. The polarizability in the insulating phase of the chain exhibits a universal scaling behavior, while the polarization charge in the metallic phase of the model is shown to be quantized in units of $e/2$.Comment: 9 pages, 3 figures, 1 tabl

The Three-Legged Stool of Evidence-Based Practice in Eating Disorder Treatment: Research, Clinical, and Patient Perspectives

Background Evidence-based practice in eating disorders incorporates three essential components: research evidence, clinical expertise, and patient values, preferences, and characteristics. Conceptualized as a ‘three-legged stool’ by Sackett et al. in 1996 (BMJ), all of these components of evidence-based practice are considered essential for providing optimal care in the treatment of eating disorders. However, the extent to which these individual aspects of evidence-based practice are valued among clinicians and researchers is variable, with each of these stool ‘legs’ being neglected at times. As a result, empirical support and patient preferences for treatment are not consistently considered in the selection and implementation of eating disorder treatment. In addition, clinicians may not have access to training to provide treatments supported by research and preferred by patients. Despite these challenges, integrating these three components of evidence-based practice is critical for the effective treatment of eating disorders. Discussion Current research supports the use of several types of psychotherapies, including cognitive-behavioral, interpersonal, and family-based therapies, as well as certain types of medications for the treatment of eating disorders. However, limitations in current research, including sample heterogeneity, inconsistent efficacy, a paucity of data, the need for tailored approaches, and the use of staging models highlight the need for clinical expertise. Although preliminary data also support the importance of patient preferences, values, and perspectives for optimizing treatment, enhancing treatment outcome, and minimizing attrition among patients with eating disorders, the extent to which patient preference is consistently predictive of outcome is less clear and requires further investigation. Summary All three components of evidence-based practice are integral for the optimal treatment of eating disorders. Integrating clinical expertise and patient perspective may also facilitate the dissemination of empirically-supported and emerging treatments as well as prevention programs. Further research is imperative to identify ways in which this three-legged approach to eating disorder treatment could be most effectively implemented

Efficient Model Learning for Human-Robot Collaborative Tasks

We present a framework for learning human user models from joint-action demonstrations that enables the robot to compute a robust policy for a collaborative task with a human. The learning takes place completely automatically, without any human intervention. First, we describe the clustering of demonstrated action sequences into different human types using an unsupervised learning algorithm. These demonstrated sequences are also used by the robot to learn a reward function that is representative for each type, through the employment of an inverse reinforcement learning algorithm. The learned model is then used as part of a Mixed Observability Markov Decision Process formulation, wherein the human type is a partially observable variable. With this framework, we can infer, either offline or online, the human type of a new user that was not included in the training set, and can compute a policy for the robot that will be aligned to the preference of this new user and will be robust to deviations of the human actions from prior demonstrations. Finally we validate the approach using data collected in human subject experiments, and conduct proof-of-concept demonstrations in which a person performs a collaborative task with a small industrial robot

Nuclear Magnetic Resonance and Hyperfine Structure

Contains research objectives and reports on two research projects

Quantum Computation with Quantum Dots

We propose a new implementation of a universal set of one- and two-qubit gates for quantum computation using the spin states of coupled single-electron quantum dots. Desired operations are effected by the gating of the tunneling barrier between neighboring dots. Several measures of the gate quality are computed within a newly derived spin master equation incorporating decoherence caused by a prototypical magnetic environment. Dot-array experiments which would provide an initial demonstration of the desired non-equilibrium spin dynamics are proposed.Comment: 12 pages, Latex, 2 ps figures. v2: 20 pages (very minor corrections, substantial expansion), submitted to Phys. Rev.

“some kind of thing it aint us but yet its in us”: David Mitchell, Russell Hoban, and metafiction after the millennium

This article appraises the debt that David Mitchell’s Cloud Atlas owes to the novels of Russell Hoban, including, but not limited to, Riddley Walker. After clearly mapping a history of Hoban’s philosophical perspectives and Mitchell’s inter-textual genre-impersonation practice, the article assesses the degree to which Mitchell’s metatextual methods indicate a nostalgia for by-gone radical aesthetics rather than reaching for new modes of its own. The article not only proposes several new backdrops against which Mitchell’s novel can be read but also conducts the first in-depth appraisal of Mitchell’s formal linguistic replication of Riddley Walker

Corrections to the universal behavior of the Coulomb-blockade peak splitting for quantum dots separated by a finite barrier

Building upon earlier work on the relation between the dimensionless interdot channel conductance g and the fractional Coulomb-blockade peak splitting f for two electrostatically equivalent dots, we calculate the leading correction that results from an interdot tunneling barrier that is not a delta-function but, rather, has a finite height V and a nonzero width xi and can be approximated as parabolic near its peak. We develop a new treatment of the problem for g much less than 1 that starts from the single-particle eigenstates for the full coupled-dot system. The finiteness of the barrier leads to a small upward shift of the f-versus-g curve at small values of g. The shift is a consequence of the fact that the tunneling matrix elements vary exponentially with the energies of the states connected. Therefore, when g is small, it can pay to tunnel to intermediate states with single-particle energies above the barrier height V. The correction to the zero-width behavior does not affect agreement with recent experimental results but may be important in future experiments.Comment: Title changed from ``Non-universal...'' to ``Corrections to the universal...'' No other changes. 10 pages, 1 RevTeX file with 2 postscript figures included using eps