A Skyrme lattice with hexagonal symmetry

Recently it has been found that the structure of Skyrmions has a close analogy to that of fullerene shells in carbon chemistry. In this letter we show that this analogy continues further, by presenting a Skyrme field that describes a lattice of Skyrmions with hexagonal symmetry. This configuration, a novel `domain wall' in the Skyrme model, has low energy per baryon (about 6% above the Faddeev-Bogomolny bound) and in many ways is analogous to graphite. By comparison to the energy per baryon of other known Skyrmions and also the Skyrme crystal, we discuss the possibility of finding Skyrmion shells of higher charge.Comment: 12 pages, 1 figure. To appear in Phys. Lett.

Solitons, Links and Knots

Using numerical simulations of the full nonlinear equations of motion we investigate topological solitons of a modified O(3) sigma model in three space dimensions, in which the solitons are stabilized by the Hopf charge. We find that for solitons up to charge five the solutions have the structure of closed strings, which become increasingly twisted as the charge increases. However, for higher charge the solutions are more exotic and comprise linked loops and knots. We discuss the structure and formation of these solitons and demonstrate that the key property responsible for producing such a rich variety of solitons is that of string reconnection.Comment: 24 pages plus 14 figures in GIF forma

The Petrology, Mineral Chemistry And Tectonics Of Proterozoic Rift-related Igneous Rocks At Lake Nipigon, Ontario

The dominant tectonic event in the Lake Superior area was the development of the Keweenawan rift zone at approximately 1110 Ma.;Lithological sequences present within the Nipigon plate and the ages of these rocks are: passive granite and associated sub-aerial rhyolite (1536.7 +10/{dollar}-2.3{dollar} Ma); alkali basalt and lamprophyre dikes (ca. 1500 Ma); epicontinental clastic sediments of the Sibley Group ({dollar}{dollar}1108 Ma); and extensive tholeiitic diabase sills, dikes and cone sheets (1108 +4/{dollar}-2{dollar} Ma). These sequences form a shallow basinal structure which overlies Archean crust and is connected to the Lake Superior basin in the south by the Black Sturgeon Graben. An increase in intensity of rifting toward Lake Superior is suggested by the form of the igneous intrusions feeding diabase sills in the Nipigon plate.;The diabase and picritic intrusions both crystallized from fractionated magmas. The picrites are cumulate rocks derived at shallow crustal depths from a magma controlled by olivine fractionation. Picrite chills are in equilibrium with olivine phenocrysts of composition Fo{dollar}\sb{lcub}80{rcub}{dollar} and are interpreted to be the least evolved liquids observed. The diabase sills crystallized from an evolved basaltic liquid controlled by cotectic crystallization of plagioclase and lesser olivine and pyroxene.;The diabase sills occur as two 150 to 200 m thick intrusions covering an area of 11,000 km{dollar}\sp2{dollar}. The sills were emplaced under conditions approaching hydrostatic equilibrium near the Archean/Proterozoic unconformity. At the time of emplacement, the lithostatic load was probably less than 0.4 kbars. Crustal loading of the sedimentary sequence with sills enabled later magmas to erupt as basalts. Chemical variation within the sills reflects crystallization from multiple pulses of magma, minor crystal accumulation and movement of volatiles to late crystallizing parts of the sills. Variation in pyroxene crystallization sequences and the persistence of olivine during fractionation are a result of variations in a(SiO{dollar}\sb2{dollar}) in the magma. This variation may reflect the degree of contamination with siliceous crustal material.;Pre-Keweenawan passive granites and rhyolites are associated with a zone of ring faulting in northern Lake Nipigon. Partial melting of the lower crust with a heat source provided by mafic magmatism is suggested as a mechanism of producing the granites. (Abstract shortened with permission of author.

An Insurance-based Approach to Improving SME Cyber Security

There has been increasing concern in recent years about the lack of urgency in SMEs regarding security of their information. Concern stems not only from the risks the SMEs are taking not only with their own data, but also with the data they share with supply chain partners. Current surveys have shown that the situation is getting worse with human error compounded by cybercriminals exploiting weaknesses in SME systems and using them to hack supply chain hubs. In this paper, a researcher and a practitioner from the UK investigate possible reasons for SME apparent lack of interest in securing data, or developing information security management systems (ISMSs). In the absence of UK legislation, the only way SMEs are likely en masse to improve their information security is through pressure from supply chain partners and particularly supply chain hubs. The authors present an interesting development in cyber liability insurance which provides the basis for a cost-effective solution that will encourage good information assurance across the supply chain. The solution offered in association with a major International insurer is explained in detail in this paper. It has the dual advantages for participating SMEs of ensuring that they achieve a level of information assurance that will offer them actual protection, and at the same time provide them with insurance that will protect them financially against data breaches or other costly consequences of weak information security. The scheme used will provide actuarial evidence for the insurer to further refine the model. Clients that cannot show evidence of a base level of security will not get insurance cover; by contrast those assessed as being more secure will be eligible for a discount. The tool used in this model is a self-assessed version of the IASME or Cyber Essentials information assurance standards, both recently developed in the UK to meet the needs of SMEs wishing to safeguard their precious information but not possessing the resources to achieve the ISO27001 standard

Multi-soliton dynamics in the Skyrme model

We exhibit the dynamical scattering of multi-solitons in the Skyrme model for configurations with charge two, three and four. First, we construct maximally attractive configurations from a simple profile function and the product ansatz. Then using a sophisticated numerical algorithm, initially well-separated skyrmions in approximately symmetric configurations are shown to scatter through the known minimum energy configurations. These scattering events illustrate a number of similarities to BPS monopole configurations of the same charge. A simple modification of the dynamics to a dissipative regime, allows us to compute the minimal energy skyrmions for baryon numbers one to four to within a few percent.Comment: latex, 10 pages, plus 5 figures (as gif files

Textual Data Augmentation for Efficient Active Learning on Tiny Datasets

In this paper we propose a novel data augmentation approach where guided outputs of a language generation model, e.g. GPT-2, when labeled, can improve the performance of text classifiers through an active learning process. We transform the data generation task into an optimization problem which maximizes the usefulness of the generated output, using Monte Carlo Tree Search (MCTS) as the optimization strategy and incorporating entropy as one of the optimization criteria. We test our approach against a Non-Guided Data Generation (NGDG) process that does not optimize for a reward function. Starting with a small set of data, our results show an increased performance with MCTS of 26% on the TREC-6 Questions dataset, and 10% on the Stanford Sentiment Treebank SST-2 dataset. Compared with NGDG, we are able to achieve increases of 3% and 5% on TREC-6 and SST-2

Q-ball Dynamics

We investigate the dynamics of Q-balls in one, two and three space dimensions, using numerical simulations of the full nonlinear equations of motion. We find that the dynamics of Q-balls is extremely complex, involving processes such as charge transfer and Q-ball fission. We present results of simulations which illustrate the salient features of 2-Q-ball interactions and give qualitative arguments to explain them in terms of the evolution of the time-dependent phases.Comment: 37 pages, including figure

USING A ROBUST LAYERED PARSER TO ANALYSE TECHNICAL MANUAL TEXT

This article describes an experiment an which a robust parser developed by the author was used to analyse a sample of sentences taken from a software instruction manual. The parser scans the text repeatedly analysing different constructs each time. The article describes the rationale behind the work, the parsing algorithm, the development of a grammar, the preparation of the evaluation materials and the method of evaluation. The results show that a good level of performance can be attained by tailoring the grammar to the domain.En este artículo se describe un experimento en el que se utilizó un analizador sintáctico robusto, desarrollado por el propio autor, para analizar una serie de oraciones extraídas de un manual de instrucciones de un programa informático. El analizador escanea el texto de forma repetida, generando cada vez estructuras sintácticas diferentes. A su vez, se detallan el algoritmo de análisis sintáctico, la implementación de la gramática. La preparación y selección de materiales y el método de evaluación. Los resultados apuntan a que el rendimiento del analizador puede optimizarse adaptando la gramática a los diversos dominios lingüísticos

Enhancing Task-Specific Distillation in Small Data Regimes through Language Generation

Large-scale pretrained language models have led to significant improvements in Natural Language Processing. Unfortunately, they come at the cost of high computational and storage requirements that complicate their deployment on low-resource devices. This issue can be addressed by distilling knowledge from larger models to smaller ones through pseudo-labels on task-specific datasets. However, this can be difficult for tasks with very limited data. To overcome this challenge, we present a novel approach where knowledge can be distilled from a teacher model to a student model through the generation of synthetic data. For this to be done, we first fine-tune the teacher and student models, as well as a Natural Language Generation (NLG) model, on the target task dataset. We then let both student and teacher work together to condition the NLG model to generate examples that can enhance the performance of the student. We tested our approach on two data generation methods: a) Targeted generation using the Monte Carlo Tree Search (MCTS) algorithm, and b) A Non-Targeted Text Generation (NTTG) method. We evaluate the effectiveness of our approaches against a baseline that uses the BERT model for data augmentation through random word replacement. By testing this approach on the SST-2, MRPC, YELP-2, DBpedia, and TREC-6 datasets, we consistently witnessed considerable improvements over the word-replacement baseline