Feature Selection vs Theory Reformulation: A Study of Genetic Refinement of Knowledge-based Neural Networks

Expert classification systems have proven themselves effective decision makers for many types of problems. However, the accuracy of such systems is often highly dependent upon the accuracy of a human expert's domain theory. When human experts learn or create a set of rules, they are subject to a number of hindrances. Most significantly experts are, to a greater or lesser extent, restricted by the tradition of scholarship which has preceded them and by an inability to examine large amounts of data in a rigorous fashion without the effects of boredom or frustration. As a result, human theories are often erroneous or incomplete. To escape this dependency, machine learning systems have been developed to automatically refine and correct an expert's domain theory. When theory revision systems are applied to expert theories, they often concentrate on the reformulation of the knowledge provided rather than on the reformulation or selection of input features. The general assumption seems to be that the expert has already selected the set of features that will be most useful for the given task. That set may, however, be suboptimal. This paper studies theory refinement and the relative benefits of applying feature selection versus more extensive theory reformulation.     

Loss mechanisms in single-mode fiber tapers

The onset of transmission loss in four single-mode tapers is shown to coincide with the taper slope exceeding the critical slope angle at which fundamental mode cutoff occurs. This implies that the primary loss mechanism in single-mode fiber tapers is cutoff of the fundamental mode from the core. A secondary loss mechanism of coupling to the modes of a coaxial outer waveguide is also observed and modeled. Implications for fused fiber couplers are discussed.     

The homeless assessment program: A service-training model for providing disability evaluations for homeless, mentally ill individuals.

Many of the nation's homeless people suffer from unrecognized mental illnesses and do not have access to the kind of disability benefits they would be entitled to when properly assessed. The current system of disability evaluations for Social Security income claims is frequently inadequate and leaves these individuals without any source of income, health insurance, and mental health treatment. This article introduces a model of providing psychological assessments for homeless, mentally ill individuals by supervised student examiners, a model that could be replicated by other psychologists and training institutions. The authors argue that there may be a large number of homeless adults who suffer from disabling mental conditions but who are not properly diagnosed and, therefore, do not qualify for benefits. The authors propose that the model presented can help to fill a gap in services and may serve as a model of socially relevant clinical training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Technical note on cold weather installation of HDPE

In order to successfully seam HDPE flexible membrane liners (FMLs) in cold weather (less than 4·5°C (40°F), FML temperature may not be the most important factor. Secondary cold weather effects such as frozen subgrade, bridging, snow and ice removal, and worker discomfort pose a much more significant risk to the integrity of the liner installation.     

Scanning slit aperture confocal microscopy for three-dimensional imaging

A scanning confocal microscope using stationary slit apertures of variable width is described. Scanning is achieved by employing an oscillating mirror galvanometer capable of scanning images at 160 frames/s. The microscope depth-of-focus is characterized for several slit widths and shown to approach diffraction-limited performance as width decreases. Reduction of flare in images taken with narrow slit widths is demonstrated. In addition, the optical sectioning capability of the system is demonstrated using polymer casts of the vasculature of rat kidney.     

Can we confirm our theories? Can we measure causal effects?: Reply to Kazantzis et al (2001).

Correlations between psychotherapy homework (HW) and recovery from depression (DEP) could be explained by 4 models: (a) HW causes reductions in DEP; (b) reductions in DEP lead to HW compliance; (c) HW and DEP have circular causal effects on each other; and (d) HW and DEP are simultaneously influenced by a 3rd variable, such as motivation. In the D. D. Burns and D. Spangler (2000) (see record 2000-13544-005) study of HW and changes in DEP during the first 12 weeks of therapy using structural equation modeling (SEM), only the first model was consistent with the data. Still, one cannot conclude that a model is "true" or definitely confirm a causal effect, even with experimental designs. The authors recommend SEM for naturalistic and experimental designs. Quality of HW should be included in future research, as N. Kazantzis, K. R. Ronan, and F. Deane (2001) (see record 2001-05666-023) suggest. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Authenticating network attached storage

We present an architecture for network-authenticated disks that implements distributed file systems without file servers or encryption. Our system provides network clients with direct network access to remote storage