Physical Sciences and Mathematics Commons^™

Theoretical Studies Of Electron Transfer In Metal Dimers: Xy+→X+Y, Where X, Y=Be, Mg, Ca, Zn, Cd, Robert J. Cave, David V. Baxter, William A. Goddard Iii, John D. Baldeschwieler

All HMC Faculty Publications and Research

The electronic matrix element responsible for electron exchange in a series of metal dimers was calculated using ab initio wave functions. The distance dependence is approximately exponential for a large range of internuclear separations. A localized description, where the two nonorthogonal structures characterizing the electron localized at the left and right sites are each obtained self‐consistently, is found to provide the best description of the electron exchange process. We find that Gaussian basis sets are capable of predicting the expected exponential decay of the electronic interactions even at quite large internuclear distances.

Teaching With A Humanist, David Meredith

Humanistic Mathematics Network Journal

This paper is a report about a team-taught course at San Francisco State University, and what the author learned having taught it over 11 years with faculty in the humanities. As part of an interdisciplinary curriculum called NEXA, which explored the boundaries between science and the humanities, the course revealed to the author several ways mathematics and humanities pedagogies can reciprocally learn from each other and emphasize similar goals.

Patterns Of Emotion Within Mathematics Problem-Solving, Frances A. Rosamond

Humanistic Mathematics Network Journal

There is often a divide between the experience of positive emotions toward math on the part of mathematical educators and negative emotions toward math on the part of students. This paper utilizes psychologist Richard Lazarus's work on the effects of positive emotions in order to highlight their benefits for mathematical pedagogy, to explain the author's experiment applying Lazarus's theory, and to suggest ways this application might support and foster positive emotions in students.

Gresham's Law: Algorithm Drives Out Thought, Sherman K. Stein

Humanistic Mathematics Network Journal

Gresham's law in economics states, "Bad money drives good money out of circulation." An application of this law in mathematical pedagogy states that "Algorithm drives out thought." While universities are ideally places where classes are meant to develop students' independence and critical thinking skills, often mathematics courses reflect this altered version of Gresham's law. This paper demonstrates the ways traditional mathematical pedagogy has held up Gresham's law and presents several suggestions for ways to change this approach to mathematical education to focus more on critical thinking without sacrificing the necessity of algorithm.

Letter From The Editor, Issue 1, 1987, Alvin White

Humanistic Mathematics Network Journal

No abstract provided.

Applied Mathematics As Social Contract, Philip J. Davis

Humanistic Mathematics Network Journal

The author takes the position that mathematical education must redefine its goals so as to create a citizenry with sufficient knowledge to provide social backpressure on future mathematizations. This can be accomplished by increasing the part of mathematical education that is devoted to the description and interpretation of the processes of mathematization and by allowing the technicalities of the formal operations within mathematics itself to be deemphasized or automated out by computer.

Appendix

Humanistic Mathematics Network Journal

No abstract provided.

Wavenumber Selection Of Convection Rolls In A Box, Wayne Arter, Andrew J. Bernoff, A. C. Newell

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The dynamics of two‐dimensional Rayleigh–Bénard convection rolls are studied in a finite layer with no‐slip, fixed temperature upper and lower boundaries and no‐slip insulating side walls. The dominant mechanism controlling the number of rolls seen in the layer is an instability concentrated near the side walls. This mechanism significantly narrows the band of stable wavenumbers although it can take a time comparable to the long (horizontal) diffusion time scale to operate.

Sorting And Selecting In Rounds, Nicholas Pippenger

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We present upper bounds for sorting and selecting the median in a fixed number of rounds. These bounds match the known lower bounds to within logarithmic factors. They also have the merit of being “explicit modulo expansion”; that is, probabilistic arguments are used only to obtain expanding graphs, and when explicit constructions for such graphs are found, explicit algorithms for sorting and selecting will follow. Using the best currently available explicit constructions for expanding graphs, we present the best currently known explicit algorithms for sorting and selecting in rounds.

The Complexity Of Computations By Networks, Nicholas Pippenger

All HMC Faculty Publications and Research

We survey the current state of knowledge concerning the computation of Boolean functions by networks, with particular emphasis on the addition and multiplication of binary numbers.

Rigid And Nonrigid Achirality, Erica Flapan

Pomona Faculty Publications and Research

In order to completely characterize a molecule it is useful to understand the symmetries of its molecular bond graph in 3-space. For many purposes the most important type of symmetry that a molecule can exhibit is mirror image symmetry. However, the question of whether a molecular graph is equivalent to its mirror image has different interpretations depending on what assumptions are made about the rigidity of the molecular structure. If there is a deformation of 3-space taking a molecular bond graph to its mirror image then the molecule is said to be topologically achiral. If a molecular graph can be …

The Gradient Model Load Balancing Method, Frank C. H. Lin, Robert M. Keller

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A dynamic load balancing method is proposed for a class of large-diameter multiprocessor systems. The method is based on the "gradient model," which entails transferring backlogged tasks to nearby idle processors according to a pressure gradient indirectly established by requests from idle processors. The algorithm is fully distributed and asynchronous. Global balance is achieved by successive refinements of many localized balances. The gradient model is formulated so as to be independent of system topology.

A Theoretical Investigation Of Some Low-Lying Singlet States Of 1,3-Butadiene, Robert J. Cave, Ernest R. Davidson

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Results are presented from extensive ab initio calculations on several low-lying singlet states of cis- and trans-1,3-butadiene. The results indicate a qualitative difference between the cis and trans isomers for the lowest π → π* transition. For the cis isomer, the first excited singlet state of the same symmetry as the ground state is found to lie above the lowest π → π* transition, and we estimate that this is also the case for the trans isomer.

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

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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

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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.

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 …

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

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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, …

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

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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

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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 …

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

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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.

The Taman Negara Batek: A People In Transition, Paul Faulstich

Pitzer Faculty Publications and Research

Batek Negritos from the vicinity of Taman Negara National Park in West Malaysia are a hunting and gathering people presently experiencing rapid encroachment by the modern world. Under the authority of the Malaysian government, they are being encouraged to settle and to emulate Malay subsistence farming communities. Unfortunately, this strategy has had a number of adverse effects on the Batek.

Approaching Distributed Database Implementations Through Functional Programming Concepts, Robert M. Keller, Gary Lindstrom

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The application of functional programming concepts to the data representation and querying aspects of databases has been discussed by Shipman and Buneman, et al. respectively. We argue the suitability of a function-based approach to additional aspects of database systems, including updating, transaction serialization, and physical distribution and communication. It is shown how the NmergeH extension of a purely functional model permits serializable concurrent "primary site" distribution control. We also present preliminary experimental results which indicate that a reasonable degree of concurrency is attainable from the functional approach.

Measuring R And D Productivity, Richard A. Pappas, Donald S. Remer

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Measuring the productivity of an R&D organization is extremely tricky. Productivity is usually defined as a ratio of an output, like number of cars produced on an assembly line, to an input, like the wages paid the workers. While R&D may have a measurable input, the output is often intangible and difficult to quantify. This is further complicated because the return from an R&D department may not be realized for one or two decades,which means the time lag is much higher than in factory measurements. Furthermore, many researchers believe that this kind of measurement may be counterproductive,since the mere act …

Problems Of Channel Correlation And Statistical Bias In Photon-Correlation Spectroscopy, Richard C. Haskell, Gary L. Pisciotta

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Correlation between channels of the normalized photocount-rate correlation function g⁽²⁾(τ) becomes significant at high count rates and leads to a number of data-analysis problems. We derive an expression for channel correlation that is valid for a detector area of arbitrary extent and compare the theoretical predictions with measured values. A data-analysis procedure is demonstrated that employs the theoretical expression for channel correlation and provides a rigorous test of an assumed fitting function. The procedure facilitates the use of the cumulant method in determining the polydispersity of scatterers. An expression for the statistical bias of g^{(2) …}

On The Steepest Descent For Nonpotential Locally Lipschitzian Vector Fields, Alfonso Castro

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In [4] J. Neuberger gave various sufficient conditions for the solvability of nonvariational operator equations via a variant of the steepest descent method. In this note we give versions of these conditions under weaker assumptions on the smoothness of the operators.

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Thermal Stress Analysis, A. Ballantyne, H.A. Hyman, Clive L. Dym, R.C. Southworth

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This paper examines the effects of thermal loading and time history upon the thermal stresses developed in lithographic mask structures as would be expected under irradiation by intense soft x rays. The objective of this work was to examine the phenomenology of the interaction and to evaluate the limits placed upon mask dosage. The mechanics of mask failure are examined in terms of single pulse and cumulative, or fatigue, effects. A number of prototypical mask structures are investigated, which show that the application of intense pulsed sources to x‐ray lithography does not reduce the potential utility of the techique. However, …

Response Of Lithographic Mask Structures To Repetitively Pulsed X-Rays: Dynamic Response, Clive L. Dym, A. Ballantyne

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This paper addresses the issue of the dynamic response of thin lithographic mask structures to thermally induced stress fields. In particular, the impact of repetitively pulsed x‐ray sources are examined: the short duration (1–100 nsec) pulses induce large step changes in mask temperatures, which can, in turn, induce a dynamic response. The impact of conductive cooling of the mask is to reduce the repetitively pulsed problem to a series of isolated nearly identical thermal impulses of duration approximately equal to the cooling time. The importance of self‐weight and prestress is examined, and an analysis of the nonlinear dynamic response to …

Necessary And Sufficient Conditions For Certain Homology 3-Spheres To Have Smooth Zp-Actions, Erica Flapan

Pomona Faculty Publications and Research

We derive necessary and sufficient conditions for a broad class of homology 3-spheres, obtained as the gluing of two knot complements, to have Zp-actions.

We explore when a homology sphere, obtained as the gluing of two knot complements has any smooth periodic diffeomorphisms.