Friends at Mid-Century

The Isaac T. and Lida K. Johnson Lectureship, made possible by their gift, was created by the Executive Committee of the Five Years Meeting in its sessions of April, 1940. The creative minute of the Executive Committee is in part as follows: It is the duty of the Executive Committee to determine the use of this money and the Central Committee submits this recommendation: (1) that the gift be made a continuing memorial to these dear friends and (2) that the memorial be in the form of a lectureship for the Five Years Meeting, and, as it may direct, to be known as the Isaac T. and Lida K. Johnson Lectureship. It is further recommended that these lectures shall within the jurisdiction of the Executive Committee, be restricted to the field of Christian scholarship and the Christian message and its application to life. It is the confident expectation of the Executive Committee that not only the constituency of the Five Years Meeting, but all of Quakerism will be enriched by the successive messages made possible by this gift.https://digitalcommons.georgefox.edu/quakerbooks/1072/thumbnail.jp

Capacity and Complexity of HMM Duration Modeling Techniques

The ability of a standard hidden Markov model (HMM) or expanded state HMM (ESHMM) to accurately model duration distributions of phonemes is compared with specific duration-focused approaches such as semi-Markov models or variable transition probabilities. It is demonstrated that either a three-state ESHMM or a standard HMM with an increased number of states is capable of closely matching both Gamma distributions and duration distributions of phonemes from the TIMIT corpus, as measured by Bhattacharyya distance to the true distributions. Standard HMMs are easily implemented with off-the-shelf tools, whereas duration models require substantial algorithmic development and have higher computational costs when implemented, suggesting that a simple adjustment to HMM topologies is perhaps a more efficient solution to the problem of duration than more complex approaches

Examining the Relationship Between Road Structure and Burglary Risk Via Quantitative Network Analysis

OBJECTIVES: To test the hypothesis that the spatial distribution of residential burglary is shaped by the configuration of the street network, as predicted by, for example, crime pattern theory. In particular, the study examines whether burglary risk is higher on street segments with higher usage potential. METHODS: Residential burglary data for Birmingham (UK) are examined at the street segment level using a hierarchical linear model. Estimates of the usage of street segments are derived from the graph theoretical metric of betweenness, which measures how frequently segments feature in the shortest paths (those most likely to be used) through the network. Several variants of betweenness are considered. The geometry of street segments is also incorporated—via a measure of their linearity—as are several socio-demographic factors. RESULTS: As anticipated by theory, the measure of betweenness was found to be a highly-significant predictor of the burglary victimization count at the street segment level for all but one of the variants considered. The non-significant result was found for the most localized measure of betweenness considered. More linear streets were generally found to be at lower risk of victimization. CONCLUSIONS: Betweenness offers a more granular and objective means of measuring the street network than categorical classifications previously used, and its meaning links more directly to theory. The results provide support for crime pattern theory, suggesting a higher risk of burglary for streets with more potential usage. The apparent negative effect of linearity suggests the need for further research into the visual component of target choice, and the role of guardianship

Improved laser ranging accuracy through dynamic threshold compensation

During a polar motion experiment (in which two laser ranging systems on a north-south line simultaneously tracked a satellite to determine motion of the pole), techniques for improving both the range noise and range bias were demonstrated. The corrections to the measured ranges (based on received signal levels relative to a fixed correction that would have been applied if pulse height information was not available) are given. It was shown that even existing long pulse systems (20 to 40 nsec duration) can be improved to the 20 to 30 cm level of precision without major or expensive changes to the system

(Op)lax natural transformations, twisted quantum field theories, and "even higher" Morita categories

Motivated by the challenge of defining twisted quantum field theories in the context of higher categories, we develop a general framework for lax and oplax transformations and their higher analogs between strong (∞,n)-functors. We construct a double (∞,n)-category built out of the target (∞,n)-category governing the desired diagrammatics. We define (op)lax transformations as functors into parts thereof, and an (op)lax twisted field theory to be a symmetric monoidal (op)lax natural transformation between field theories. We verify that lax trivially-twisted relative field theories are the same as absolute field theories. As a second application, we extend the higher Morita category of E d -algebras in a symmetric monoidal (∞,n)-category C to an (∞,n+d)-category using the higher morphisms in C

Finite-state compensators for continuous processes

Mathematical representation of feedback systems composed of both continuous and finite-state processes is discussed. Such a representation provides a new viewpoint for the design of computer control systems for industrial processes, and clarifies areas in which further research is required. Some motivating examples are provided