Finite-particle representations and states of the canonical commutation relations.

Massachusetts Institute of Technology. Dept. of Mathematics. Thesis. 1966. Ph.D.Bibliography: leaves 104-106.Ph.D

Nonequilibrium stationary states and equilibrium models with long range interactions

It was recently suggested by Blythe and Evans that a properly defined steady state normalisation factor can be seen as a partition function of a fictitious statistical ensemble in which the transition rates of the stochastic process play the role of fugacities. In analogy with the Lee-Yang description of phase transition of equilibrium systems, they studied the zeroes in the complex plane of the normalisation factor in order to find phase transitions in nonequilibrium steady states. We show that like for equilibrium systems, the ``densities'' associated to the rates are non-decreasing functions of the rates and therefore one can obtain the location and nature of phase transitions directly from the analytical properties of the ``densities''. We illustrate this phenomenon for the asymmetric exclusion process. We actually show that its normalisation factor coincides with an equilibrium partition function of a walk model in which the ``densities'' have a simple physical interpretation.Comment: LaTeX, 23 pages, 3 EPS figure

Evaluative conditioning effects are modulated by the nature of contextual pairings

Across two studies participants completed a learning phase comprised of two types of trials: context pairing trials in which two (valenced or non-valenced) words were identical or opposite to one another and evaluative conditioning (EC) trials in which a CS was paired with a US. Based on the idea that EC occurs because CS-US pairings function as a symbolic cue about the relation between the CS and the US, we hypothesized that the nature of context pairings (identical or opposite) might moderate EC effects. Results indicate that identity-based context pairs led to typical assimilative explicit and implicit effects whereas opposition-based pairs led to attenuated effects. Implications and different accounts of our findings are discussed

When people co-occur with good or bad events: graded effects of relational qualifiers on evaluative conditioning

Studies on evaluative conditioning show that a change in liking can occur whenever stimuli are paired. Such instances of attitude change are known to depend on the type of relation established between stimuli (e.g., “Bob is a friend of Mike” vs. “Bob is an enemy of Mike”). Research has so far only compared assimilative and contrastive relational qualifiers (e.g., friend vs. enemy). For the first time, we compared the effect of non-oppositional qualifiers on attitude change in a EC procedure (e.g., “Bob causes Positive Outcomes” vs. “Bob predicts Positive Outcomes”). Differential effects of non-oppositional relational qualifiers were observed on explicit and implicit evaluations. We discuss the implications of our findings for attitude research, theories of attitude change, and for optimizing evaluative conditioning for changing attitudes in applied settings

Transfer of Emergency Service Deployment Models to Operating Agencies

Six deployment models for emergency service agencies were developed, field-tested, and documented during a two-year period ending October 1975. During the following eighteen months, records were kept of the extent to which the models were acquired by operating agencies and actually used for making deployment changes. The number of acquisitions ranged from zero for one model to 39 for another. Over half of those who acquire these models actually use them, and, except for one model, nearly all users made operational changes based on the output. Differences among the models illuminate the implementation process.

A Patrol Car Allocation Model: Background

Before designing a computer program for allocating police patrol cars by time and geography, a review was undertaken of previously existing programs of this type. Nearly all of the programs calculated queuing statistics for the collection of patrol cars by assuming a steady-state system with calls for service arriving within priority levels according to Poisson processes and having independent, identical, exponentially distributed service times. Unavailabilities of patrol cars for reasons other than calls for service were handled in the models either by artificially increasing the arrival rate of calls or by assuming that the number of servers is smaller than the number of patrol cars. Some programs calculated additional performance measures such as travel times and preventive patrol frequencies. All the programs had the capabilities to describe performance statistics for an allocation proposed by the user, but they differed in their capabilities to prescribe desirable allocations. None of the programs had achieved general acceptance because each had virtues and inadequacies not present in the others.government: services, police, programming: multiple criteria, queues: applications

Methods for Allocating Urban Emergency Units

An urban emergency service system provides mobile units (vehicles) to respond to requests for service which can occur at any time and any place throughout a city. This paper surveys recent quantitative work aimed at improving the allocation policies of these systems, including determining the number of units on duty, designing response areas and patrol patterns, and locating service facilities. Recent models which provide insight into system operation are proposed to replace traditional rules-of-thumb as guides to allocation decision-making. The methods discussed are applicable to police and fire departments, emergency ambulance services, and certain other emergency service.U. S. Department of Housing and Urban Development under Grant H-1056 and in part by the National Science Foundation under Grants GK-16471 and GI-5

Methods for Allocating Urban Emergency Units: A Survey

An urban emergency service system provides mobile units (vehicles) to respond to requests for service which can occur at any time and any place throughout a city. This paper describes the common characteristics and operational problems of these systems and surveys the various methods, both traditional and recently developed, which may be used for allocating their units. Aspects of allocation policy discussed include (1) determining the number of units to have on duty, (2) locating the units, (3) designing their response areas or patrol areas, (4) relocating units, and (5) planning preventive-patrol patterns for police cars. Typical policy changes which may be suggested by the use of quantitative allocation models include selective queuing of low priority calls, varying the number of units on duty (and their locations) by time of day, dispatching units other than the closest ones to certain incidents, relocating units as unavailabilities begin to develop, and assigning police cars to overlapping patrol sectors. As a result of making such changes, it is often possible to reduce queuing and travel time delays, improve the balance of workload among units, and enhance the amount of preventive patrol where needed.

Response to Communication on Rand-HUD Fire Models

The Communication from Rodrick and Deborah Wallace repeats allegations that they have made in print [Wallace, D. 1977. New York city fire crisis, part one, the system is falling apart. Heights and Valley News (May) 10--11; Wallace, R., D. Wallace. 1977. Studies on the Collapse of Fire Service in New York City 1972--1976: The Impact of Pseudoscience in Public Policy (pamphlet), Univ. Press of America, Washington, D.C.] and in various forums for more than three years. Their critique is not of Chaiken's paper, "Transfer of Emergency Service Deployment Models to Operating Agencies," (Chaiken, J. 1978. Transfer of emergency service deployment models to operating agencies. Management Sci. 24 (7) 719--731.) but rather they use the appearance of that paper as an occasion to comment again on the application of Rand's fire deployment models in New York City during the period from 1972 to 1976. Readers of Chaiken's paper who are not familiar with this history are likely to wonder how his paper, which barely mentions New York City, inspired the Wallaces' comments in this Communication.