Validation of Expert System Performance

Most definitions of an expert system include some reference to the ability of the system to perform at a level close to human expert performance. Yet the validation of expert systems, that is, the testing of systems so as to ascertain that they achieve an acceptable level of performance, has (with a few exceptions) been ad-hoc, informal, and in some cases of dubious value. This paper attempts to establish validation as an important concern in expert systems research and development. The problems in validating an expert system are discussed, and a number of methods for validating expert systems, both qualitative and quantitative, are presented

Monitoring the operation of a graphene transistor in an integrated circuit by XPS

One of the transistors in an integrated circuit fabricated with graphene as the current controlling element, is investigated during its operation, using a chemical tool, XPS. Shifts in the binding energy of C1s are used to map out electrical potential variations, and compute sheet resistance of the graphene layer, as well as the contact resistances between the metal electrodes. Measured shifts depend on lateral positions probed, as well as on polarity and magnitude of the gate-voltage. This non-contact and chemically specific characterization can be pivotal in diagnoses. © 2016 Elsevier B.V

Magnetic Field Dependence of Electronic Specific Heat in Pr_{1.85} Ce_{0.15} CuO_4

The specific heat of electron-doped Pr_{1.85} Ce_{0.15} CuO_4 single crystals is reported for the temperature range 2 - 10 K and magnetic field range 0 - 10 T. A non-linear magnetic field dependence is observed for the field range 0 - 2 T. Our data supports a model with lines of nodes in the gap function of these superconductors. Theoretical calculations of the electronic specific heat for dirty d-wave, clean d-wave, and s-wave symmetries are compared to our data.Comment: 10 pages Latex and 4 eps figures, submitted to Phys. Rev.

Nernst Effect in Electron-Doped Pr2−x_{2-x}Cex_{x}CuO4_4

The Nernst effect of Pr$_{2-x}$Ce$_{x}$CuO$_4$ (x=0.13, 0.15, and 0.17) has been measured on thin film samples between 5-120 K and 0-14 T. In comparison to recent measurements on hole-doped cuprates that showed an anomalously large Nernst effect above the resistive T$_c$ and H$_{c2}$ \cite{xu,wang1,wang2,capan}, we find a normal Nernst effect above T$_c$ and H$_{c2}$ for all dopings. The lack of an anomalous Nernst effect in the electron-doped compounds supports the models that explain this effect in terms of amplitude and phase fluctuations in the hole-doped cuprates. In addition, the H$_{c2}$(T) determined from the Nernst effect shows a conventional behavior for all dopings. The energy gap determined from H$_{c2}$(0) decreases as the system goes from under-doping to over-dopingin agreement with the recent tunnelling experiments

Erdheim Chester disease presented isolated breast and axillary involvement

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis of unknown aetiology. The most common sites of involvement are the long bones, skin, orbit, pituitary and retroperitoneal space. Isolated breast involvement is rare in the literature. ECD of the breast has been rarely reported. ECD should be considered in the differential diagnosis of histiocytoid breast lesions, including fat necrosis and histiocytoid invasive mammary carcinoma. In this case report, we present an unusual presentation isolated breast involvement of ECD with radiological and histopathology findings

Toward an analog neural substrate for production systems

Symbolic, rule-based systems seem essential for modeling high-level cognition. Subsymbolic dynamical systems, in con-trast, seem essential for modeling low-level perception and ac-tion, and can be mapped more easily onto the brain. Here we review existing work showing that critical features of sym-bolic production systems can be implemented in a subsym-bolic, dynamical systems substrate, and that optimal tuning of connections between that substrate’s analog circuit elements accounts for fundamental laws of behavior in psychology. We then show that emergent properties of these elements are re-flected in behavioral and electrophysiological data, lending support to a theory about the physical substructure of produc-tions. The theory states that: 1) productions are defined by connection strengths between circuit elements; 2) conflict res-olution among competing productions is equivalent to optimal hypothesis testing; 3) sequential process timing is parallel and distributed; 4) memory allocation and representational binding are controlled by competing relaxation oscillators

Evidence of a d to s-wave pairing symmetry transition in the electron-doped cuprate superconductor Pr2−x_{2-x}Cex_xCuO4_4

We present point contact spectroscopy (PCS) data for junctions between a normal metal and the electron doped cuprate superconductor Pr$_{2-x}$Ce$_x$CuO$_4$ (PCCO). For the underdoped compositions of this cuprate ($x \sim 0.13$) we observe a peak in the conductance-voltage characteristics of the point contact junctions. The shape and magnitude of this peak suggests the presence of Andreev bound states at the surface of underdoped PCCO which is evidence for a d-wave pairing symmetry. For overdoped PCCO ($x \sim 0.17$) the PCS data does not show any evidence of Andreev bound states at the surface suggesting an s-wave pairing symmetry.Comment: 4 pages Latex, 4 eps figures included. Submitted to Phys. Rev. Let