Diagnosis by integrating model-based reasoning with knowledge-based reasoning

Our research investigates how observations can be categorized by integrating a qualitative physical model with experiential knowledge. Our domain is diagnosis of pathologic gait in humans, in which the observations are the gait motions, muscle activity during gait, and physical exam data, and the diagnostic hypotheses are the potential muscle weaknesses, muscle mistimings, and joint restrictions. Patients with underlying neurological disorders typically have several malfunctions. Among the problems that need to be faced are: the ambiguity of the observations, the ambiguity of the qualitative physical model, correspondence of the observations and hypotheses to the qualitative physical model, the inherent uncertainty of experiential knowledge, and the combinatorics involved in forming composite hypotheses. Our system divides the work so that the knowledge-based reasoning suggests which hypotheses appear more likely than others, the qualitative physical model is used to determine which hypotheses explain which observations, and another process combines these functionalities to construct a composite hypothesis based on explanatory power and plausibility. We speculate that the reasoning architecture of our system is generally applicable to complex domains in which a less-than-perfect physical model and less-than-perfect experiential knowledge need to be combined to perform diagnosis

Optical excitations of Si by time-dependent density-functional theory based on the exact-exchange Kohn-Sham band structure

We calculate the imaginary part of the frequency-dependent dielectric function of bulk silicon by applying time-dependent density-functional theory based on the exact-exchange (EXX) Kohn-Sham (KS) band structure and the adiabatic local-density approximation (ALDA) kernel. The position of the E2 absorption peak calculated with the EXX band structure at the independent-particle level is in excellent agreement with experiments, which demonstrates the good quality of EXX `KS quasiparticles'. The excitonic E1 peak that is missing at the independent-particle level remains absent if two-particle interaction effects are taken into account within the time-dependent LDA, demonstrating the incapability of the ALDA kernel to describe excitonic effects.Comment: 6 pages, 2 figures; contribution to "DFT 2001", Sep. 10-14, San Lorenzo de El Escorial, Spain; to be published in Int. J. Quantum. Che

High Kinetic Inductance NbN Nanowire Superinductors

We demonstrate that a high kinetic inductance disordered superconductor can realize a low microwave loss, non-dissipative circuit element with an impedance greater than the quantum resistance ($R_Q = h/4e^2 \simeq 6.5k\Omega$). This element, known as a superinductor, can produce a quantum circuit where charge fluctuations are suppressed. The superinductor consists of a 40 nm wide niobium nitride nanowire and exhibits a single photon quality factor of $2.5 \times 10^4$. Furthermore, by examining loss rates, we demonstrate that the dissipation of our nanowire devices can be fully understood in the framework of two-level system loss

Line Widths of Single-Electron Tunneling Oscillations: Experiment and Numerical Simulations

We present experimental and numerical results from a real-time detection of time-correlated single-electron tunneling oscillations in a one-dimensional series array of small tunnel junctions. The electrons tunnel with a frequency f=I/e, where I is the current and e is the electron charge. Experimentally, we have connected a single-electron transistor to the last array island, and in this way measured currents from 5 fA to 1 pA by counting the single electrons. We find that the line width of the oscillation is proportional to the frequency f. The experimental data agrees well with numerical simulations.Comment: 2 pages, 1 figure. Submitted to the 24th International Conference on Low Temperature Physics (LT24), Orlando, FL, USA, Aug. 2005; to be published in the AIP Conference Proceedings serie

Direct observation of time correlated single-electron tunneling

We report a direct detection of time correlated single-electron tunneling oscillations in a series array of small tunnel junctions. Here the current, I, is made up of a lattice of charge solitons moving throughout the array by time correlated tunneling with the frequency f=I/e, where e is the electron charge. To detect the single charges, we have integrated the array with a radio-frequency single-electron transistor (RF-SET) and employed two different methods to couple the array to the SET input: by direct injection through a tunnel junction, and by capacitive coupling. In this paper we report the results from the latter type of charge input, where we have observed the oscillations in the frequency domain and measured currents from 50 to 250 fA by means of electron counting.Comment: 2 pages, 1 figure; submitted to the 10th International Superconductive Electronics Conference (ISEC'05), the Netherlands, Sept. 200

Noise and loss of superconducting aluminium resonators at single photon energies

The loss and noise mechanisms of superconducting resonators are useful tools for understanding decoherence in superconducting circuits. While the loss mechanisms have been heavily studied, noise in superconducting resonators has only recently been investigated. In particular, there is an absence of literature on noise in the single photon limit. Here, we measure the loss and noise of an aluminium on silicon quarter-wavelength ($\lambda/4$) resonator in the single photon regime.Comment: LT28 Conference proceeding, to be published in IOP Conference Serie

Looking elsewhere : migration, risk, and decision-making in rural Cambodia

textInternational labor migration has become an increasingly common livelihood strategy in rural Cambodia, in some villages becoming a defining and normative part of community life. This dissertation is an ethnographic study of one such rural community, where migration to Thailand has become a primary livelihood strategy over the past decade. Drawing on three years of fieldwork in Chanleas Dai, a commune (khum) in Northwest Cambodia, my research explores the complexities of the migration decision-making process, and the meanings of migration for rural households. This work is motivated by debates within the dialogues of migration and development, most of which seek to understand the potential for migration to promote development by focusing on the impacts of migration. My work departs from previous studies by focusing explicitly on decision-making, seeking to understand how and why families make developmentally important migration decisions. This is a critical area of inquiry, as the potential that migration has to promote or sustain development rests on a series of individual choices, for example who migrates, or how households invest remittances. Yet research tends to focus on the outcomes of these choices, neglecting a sufficient understanding of why they were made. In Chanleas Dai individuals are deeply ambivalent about migration, understanding it as both a constituent cause of insecurity and also the best path to security, mobility, and status. Whereas migration is perceived as low-risk and high-reward, village-based livelihoods are widely perceived as insufficient, impossible, or too financially risky to be meaningful. These perceptions are strongly linked to the recent history of environmental distress in the area. As a result, households often prioritize investment in further migrations, rather than using wages earned abroad for local investment or production. This is particularly true among youth, who see few potential worthwhile strategies to "make it" at home. Credit and agriculture programs theorized to curb migration, and/or promote local investment have not substantively challenged these perceptions. My conclusions discuss these findings in terms of their implications for the migration and development dialogues, definitions and understandings of development, and rural development policies both within and outside of Cambodia.Sociolog

Evidence in Civil Law - Sweden

This publication is based on the Swedish report to the project Dimensions of Evidence in Civil Procedure. The major objective of the project has been to explore whether there exists a common core of European Law of Evidence, and if it does, to describe its content and its most important points of discord among the national legal systems. By providing a clear picture of common core principles, the project can serve as a starting point for further harmonisation or unification processes in this field. A basic assumption of the project is that there can be no trust without a clear picture what courts do in matters of evidence, and how they discover the facts. This publication presents the relevant aspects of the Swedish legal system. The Swedish system for adjunction seldom takes its ground in firmly defined principles, but principles appear in decisions ad hoc. The Swedish application of the principle of free production of evidence and the principle of free assessment of evidence are far-reaching

Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wavefunction traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories give rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations of the transition rate exhibit a sharp peak when the drive is time-symmetric, similar to universal conductance fluctuations in electronic transport through mesoscopic systems

Improved content mastery and written communication through a lab-report assignment with peer review: an example from a quantum engineering course

The promotion of high-quality written communication in the disciplines is an important learning outcome in higher education. Given the time invested by students and teachers alike, it is crucial that writing assignments also promote engagement and content learning. But is it worth the time for university teachers to invest in such \u27writing-to-learn\u27 activityes? We find that it can be, and present an improved design for an experimental lab-report writing assignment in an English medium instruction environment, where English is an additional language. Our context is assignment development for formative assessment in master\u27s-level physics, but the method is broadly applicable within the science-technology-engineering-math disciplines. Our first experience with the assignment resulted in substandard lab reports, suggesting insufficient subject understanding and prompting this assignment design. We therefore focused on communicating the alignment of aims, learning objectives, instruction, assessment criteria, and feedback design, and developed simplified rubrics facilitating assessment fairness and efficiency. The revised assignment enhanced the learning of the subject matter and the writing quality over the four years of the study, indicated by clearly improved reports and relevant peer feedback comments. The learning activity also had an observable but less distinct effect on the students\u27 exam performance