Physical Sciences and Mathematics Commons^™

Do We Really Know What Makes Educational Software Effective? A Call For Empirical Research On Effectiveness, Karen Jolicoeur, Dale E. Berger

CGU Faculty Publications and Research

Empirical information on specific factors that make educational software effective in reaching instructional objectives would be of considerable value. The authors describe the current state of evaluation research with educational software and discuss how popular software review methods fall short of meeting our need to know how well specific programs work.

Computers And The Nature Of Man: A Historian's Perspective On Controversies About Artificial Intelligence, Judith V. Grabiner

Pitzer Faculty Publications and Research

The purpose of the present paper is to provide a historical perspective on recent controversies, from Turing's time on, about artificial intelligence, and to make clear that these are in fact controversies about the nature of man. First, I shall briefly review three recent controversies about artificial intelligence, controversies over whether computers can think and over whether people are no more than information-processing machines. These three controversies were each initiated by philosophers who, irrespective of what the programs of their time actually did, viewed with alarm the argument that if a machine can think, a thinking being is just a …

Distributed Recovery In Applicative Systems, Frank C. H. Lin, Robert M. Keller

All HMC Faculty Publications and Research

Applicative systems are promising candidates for achieving high performance computing through aggregation of processors. This paper studies the fault recovery problems in a class of applicative systems. The concept of functional checkpointing is proposed as the nucleus of a distributed recovery mechanism. This entails incrementally building a resilient structure as the evaluation of an applicative program proceeds. A simple rollback algorithm is suggested to regenerate the corrupted structure by redoing the most effective functional checkpoints. Another algorithm, which attempts to recover intermediate results, is also presented. The parent of a faulty task reproduces a functional twin of the failed task. …

A Semiclassical Model For Orientation Effects In Electron Transfer Reactions, Robert J. Cave, Stephen J. Klippenstein, R.A. Marcus

All HMC Faculty Publications and Research

An approximate solution to the single‐particle Schrödinger equation with an oblate spheroidal potential well of finite depth is presented. The electronic matrix element H_BA for thermal electron transfer is calculated using these wave functions, and is compared with values of H_BA obtained using the exact solution of the same Schrödinger equation. The present method yields accurate results for H_BA, within the oblate spheroidal potential well model, and is useful for examining the orientational effects of the two centers on the rate of electron transfer.

Chemical Applications Of Scanning Tunneling Microscopy, Paul West, John Kramer, David V. Baxter, Robert J. Cave, John D. Baldeschwieler

All HMC Faculty Publications and Research

The development of a scanning tunneling microscope at the California Institute of Technology is well under way. Electron tunneling has been demonstrated, and preliminary surface images of gold films have been obtained. Additional instrumental development is required to achieve the atomic resolution which is required for the study of chemical processes on surfaces. A theoretical model is also being developed for the study of tunneling of electrons from the probe to surfaces with molecular species absorbed, and with atomic and molecular species intervening between the probe and the surface. These experimental tools and theoretical models, which are being developed concurrently, …

Mutual Orientation Effects On Electron-Transfer Reactions Between Porphyrins, Robert J. Cave, Paul Siders, R.A. Marcus

All HMC Faculty Publications and Research

Mutual orientation effects on the rate of nonadiabatic electron transfer between several diporphyrin pairs of experimental interest are examined. The electronic matrix element for electron transfer is calculated within a one-electron spheroidal model for a variety of states and orientations which are relevant to both biological and synthetic electron-transfer systems. Both the mutual orientation of the pairs and the nodal structure of the donor and acceptor orbitals can have large effects on calculated rates.

Alphabetic Minimax Trees Of Degree At Most T*, D. Coppersmith, Maria M. Klawe, Nicholas Pippenger

All HMC Faculty Publications and Research

Problems in circuit fan-out reduction motivate the study of constructing various types of weighted trees that are optimal with respect to maximum weighted path length. An upper bound on the maximum weighted path length and an efficient construction algorithm will be presented for trees of degree at most t, along with their implications for circuit fan-out reduction.

Reliable Computation In The Presence Of Noise, Nicholas Pippenger

All HMC Faculty Publications and Research

This talk concerns computation by systems whose components exhibit noise (that is, errors committed at random according to certain probabilistic laws). If we aspire to construct a theory of computation in the presence of noise, we must possess at the outset a satisfactory theory of computation in the absence of noise.

A theory that has received considerable attention in this context is that of the computation of Boolean functions by networks (with perhaps the strongest competition coming from the theory of cellular automata; see [G] and [GR]). The theory of computation by networks associates with any two sets Q and …

A Prime Strongly Positive Amphicheiral Knot Which Is Not Slice, Erica Flapan

Pomona Faculty Publications and Research

We begin by giving several definitions. A knot K in S³ is said to be amphicheiral if there is an orientation-reversing diffeomorphism h of S³ which leaves K setwise invariant. Suppose, in addition, that K is given an orientation. ThenK is said to be positive amphicheiral if h preserves the orientation of K. If, in addition, the diffeomorphism h is an involution then K is strongly positive amphicheiral. Finally, we say a knot is slice if it bounds a smooth disc in B⁴. In this note we shall give a smooth example of …