Two Quasi p-Groups

Recently, I set out to find and classify all the quasi p-groups of order less than 24. For most groups of order less than 24, it was easy to check whether or not the group was a quasi p-group for some prime p. But there were two of these groups, one of order 18 and one of order 20, that required much more thought and analysis. The analysis of these two groups explores the interesting structure of the semidirect product. The purpose of this paper is to examine these two groups and show that they are both quasi 2-groups

Deep Metric Learning and Image Classification with Nearest Neighbour Gaussian Kernels

We present a Gaussian kernel loss function and training algorithm for convolutional neural networks that can be directly applied to both distance metric learning and image classification problems. Our method treats all training features from a deep neural network as Gaussian kernel centres and computes loss by summing the influence of a feature's nearby centres in the feature embedding space. Our approach is made scalable by treating it as an approximate nearest neighbour search problem. We show how to make end-to-end learning feasible, resulting in a well formed embedding space, in which semantically related instances are likely to be located near one another, regardless of whether or not the network was trained on those classes. Our approach outperforms state-of-the-art deep metric learning approaches on embedding learning challenges, as well as conventional softmax classification on several datasets.Comment: Accepted in the International Conference on Image Processing (ICIP) 2018. Formerly titled Nearest Neighbour Radial Basis Function Solvers for Deep Neural Network

Quasi p or not Quasi p? That is the Question

The question might not be as profound as Shakespeare\u27s, but nevertheless, it is interesting. Because few people seem to be aware of quasi p-groups, we will begin with a bit of history and a definition; and then we will determine for each group of order less than 24 (and a few others) whether the group is a quasi p-group for some prime p or not. This paper is a prequel to [Hwd]. In [Hwd] we prove that (Z3 x Z3) x Z2 and Z5 x Z4 are quasi 2-groups. Those proofs now form a portion of Proposition (12.1) It should also be noted that [Hwd] may also be found in this journal

Crystal-Chemical Relationships in Kimberlitic and Non-kimberlitic Garnets and Ilmenites

A detailed investigation of the relationship between crystal structure and chemical composition was conducted for a suite of kimberlitic garnets, and kimberlitic and non- kimberlitic ilmenites. The results for garnet showed clear trends of increasing unit cell with increasing calcium and chromium contents. Increases in unit cell occurred parallel to the divisions between major garnet types, making unit cell ineffective as a discrimination tool for diamond exploration, although it could have application to skarn exploration. Kimberlitic and non-kimberlitic ilmenites did not follow well defined trends and the two sources could not be distinguished by their unit cell dimensions. This work also outlines several issues concerning the footprint of the incident X-ray beam ofthe Briiker D8 Discover at low glancing angles, and makes recommendations for future studies. In addition, a new method is reported that allows partially automated thin section mapping, providing modal mineralogy and 2D maps of the thin section

Delta Descriptors: Change-Based Place Representation for Robust Visual Localization

Visual place recognition is challenging because there are so many factors that can cause the appearance of a place to change, from day-night cycles to seasonal change to atmospheric conditions. In recent years a large range of approaches have been developed to address this challenge including deep-learnt image descriptors, domain translation, and sequential filtering, all with shortcomings including generality and velocity-sensitivity. In this paper we propose a novel descriptor derived from tracking changes in any learned global descriptor over time, dubbed Delta Descriptors. Delta Descriptors mitigate the offsets induced in the original descriptor matching space in an unsupervised manner by considering temporal differences across places observed along a route. Like all other approaches, Delta Descriptors have a shortcoming - volatility on a frame to frame basis - which can be overcome by combining them with sequential filtering methods. Using two benchmark datasets, we first demonstrate the high performance of Delta Descriptors in isolation, before showing new state-of-the-art performance when combined with sequence-based matching. We also present results demonstrating the approach working with four different underlying descriptor types, and two other beneficial properties of Delta Descriptors in comparison to existing techniques: their increased inherent robustness to variations in camera motion and a reduced rate of performance degradation as dimensional reduction is applied. Source code is made available at https://github.com/oravus/DeltaDescriptors.Comment: 8 pages and 7 figures. Published in 2020 IEEE Robotics and Automation Letters (RA-L

Vision impairment and differential access to eye health services in Aotearoa New Zealand: protocol for a scoping review

INTRODUCTION: In Aotearoa New Zealand, Māori and Pacific people experience worse health outcomes compared with other New Zealanders. No population-based eye health survey has been conducted, and eye health services do not generate routine monitoring reports, so the extent of eye health inequality is unknown. This information is required to plan equitable eye health services. Here we outline the protocol for a scoping review to report the nature and extent of the evidence reporting vision impairment, and the use of eye health services by ethnicity in New Zealand. METHODS AND ANALYSIS: An information specialist will conduct searches on MEDLINE and Embase, with no limit on publication dates or language. We will search the grey literature via websites of relevant government and service provider agencies. Reference lists of included articles will be screened. Observational studies will be included if they report the prevalence of vision impairment, or any of the main causes (cataract, uncorrected refractive error, macular degeneration, glaucoma or diabetic retinopathy) or report the use of eye health services in New Zealand among people of any age. Two authors will independently review titles, abstracts and full-text articles, and complete data extraction. Overall findings will be summarised using descriptive statistics and thematic analysis, with an emphasis on disaggregation by ethnicity where this information is available. ETHICS AND DISSEMINATION: Ethical approval has not been sought as our review will only include published and publicly accessible data. We will publish the review in an open access peer-reviewed journal. We anticipate the findings will be useful to organisations and providers in New Zealand responsible to plan and deliver eye care services, as well as stakeholders in other countries with differential access to eye care. REGISTRATION DETAILS: The protocol has been registered with Open Science Framework (https://osf.io/yw7xb)

Abstracts

Abstracts of papers about Giuseppe Verdi and his works, presented at joint meetings of the AIVS and Greater NY Chapter of the American Musicological Society, 1979-81 (Hepokoski, Lawton, Chusid, Hornick, Nádas, Tomlinson, Garrison, Powers), at the 1982 national meeting of the American Musicological Society (Harwood), and at an NEH-sponsored summer seminar at NYU in 1980 (Beams, Cole, Cordell, Davis, Fry, King, Mason, McCauley, Town)