Mathematizing C++ concurrency

Shared-memory concurrency in C and C++ is pervasive in systems programming, but has long been poorly defined. This motivated an ongoing shared effort by the standards committees to specify concurrent behaviour in the next versions of both languages. They aim to provide strong guarantees for race-free programs, together with new (but subtle) relaxed-memory atomic primitives for high-performance concurrent code. However, the current draft standards, while the result of careful deliberation, are not yet clear and rigorous definitions, and harbour substantial problems in their details. In this paper we establish a mathematical (yet readable) semantics for C++ concurrency. We aim to capture the intent of the current (`Final Committee') Draft as closely as possible, but discuss changes that fix many of its problems. We prove that a proposed x86 implementation of the concurrency primitives is correct with respect to the x86-TSO model, and describe our Cppmem tool for exploring the semantics of examples, using code generated from our Isabelle/HOL definitions. Having already motivated changes to the draft standard, this work will aid discussion of any further changes, provide a correctness condition for compilers, and give a much-needed basis for analysis and verification of concurrent C and C++ programs

Mathematical model of welding parameters for rapid prototyping using robot welding

Rapid Prototyping is a relatively new technology that allows the creation of prototypes in a very short period of time compared with traditional manufacturing techniques. First, a model of the prototype is drawn, using a computer aided design program, which is then mathematically ‘sliced’ and used to build the prototype layer by layer, using material such as paper, resins, or thermoplastics, depending on the process. The main disadvantage of these processes is that they do not allow metal as a raw material. Rapid Prototyping using Robot welding is another approach that overcomes this problem by using a welding robot that deposits metal. As the success of the final component quality depends very much on the welding parameters, it is important to automate their calculation. To automate the task of determining the welding parameters and to generate welded components with consistent quality, a very simple mathematical algorithm was created. The tests carried out to gather the necessary information to generate this model, the mathematical model itself, the limitations of the equations, and the tests to check their feasibility are described. At the time the work was carried out, the authors were in the welding Engineering Groups, SIMS, Cranfield University, Cranfield, Beds. MK43 0SY, UK. Dr Ribeiro is now in the Department of Industrial Electronics, University of Minho, 4800 Guimarães, Portugal and Professor Norrish is in the Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522, Australia. Manuscript received 12 May 1997; in final form 20 June 1997

Draining the Swamp: Micro Virtual Machines as Solid Foundation for Language Development

Many of today\u27s programming languages are broken. Poor performance, lack of features and hard-to-reason-about semantics can cost dearly in software maintenance and inefficient execution. The problem is only getting worse with programming languages proliferating and hardware becoming more complicated. An important reason for this brokenness is that much of language design is implementation-driven. The difficulties in implementation and insufficient understanding of concepts bake bad designs into the language itself. Concurrency, architectural details and garbage collection are three fundamental concerns that contribute much to the complexities of implementing managed languages. We propose the micro virtual machine, a thin abstraction designed specifically to relieve implementers of managed languages of the most fundamental implementation challenges that currently impede good design. The micro virtual machine targets abstractions over memory (garbage collection), architecture (compiler backend), and concurrency. We motivate the micro virtual machine and give an account of the design and initial experience of a concrete instance, which we call Mu, built over a two year period. Our goal is to remove an important barrier to performant and semantically sound managed language design and implementation

An Exploratory Study Into Stakeholder Perceptions of a Proposed Geotrail in the Perth Hills

Geotourism is a form of natural area tourism that can include natural and human-made sites of geological significance. This new form of tourism provides destinations with an opportunity to provide a unique product to visitors. The purpose of the study was to explore the perceptions of tourism stakeholders on a proposed geotrail in the Perth Hills. Due to the limitation of appropriate frameworks and models surrounding geotourism development, Steps 1 to 5 of Gunn\u27s (2002) Site Design Steps was used for the identification and development of individual geosites within a proposed geotourism trail in the Perth Hills. Fourteen tourism stakeholders were identified using a snow-ball interview technique, with convenience sampling used to identify prospective tourists. Participants were given a \u27key stakeholder information booklet\u27 prior to the in-depth, semi-structured interviews conducted between September and November 2010. The findings were combined to create a market analysis of the tourism industry in Western Australia and the eastern region of Perth. The market analysis identified the different tourism markets, characteristics of visitors, existing tourism products, established geotourism products, current major tourist attractions in Perth and the surrounding areas, and new market opportunities for geotourism and geotrails within the Perth area. The program definition of the project identified three significant geosites in the Perth Hills- the Red Hill quarry, Boya Mountain Quarry and the Zig Zag. These sites were then assessed for their on-site and off-site factors and provided to stakeholders for consideration as geosites within the proposed geotrail. Although there were differences on how each stakeholder group perceived the geotrail, each group supported the geotrail plan and viewed it as an opportunity to increase tourism in the Perth Hills. Without the input of stakeholders various concerns with the geotrail would not have been realised, relating back to the reviewed literature and influencing the amended geotrail route. Overall, stakeholders that were interviewed found the geotrail plan to be an interesting concept. However, there were some doubts as to how successful the trail would be and if there would be enough visitations to warrant the development of the trail. However, the general consensus of the interviews was that any new product that would create an increase in tourism in the Perth Hills and provide visitors with more activities would be supported by all stakeholder groups

Racial Variation in Echocardiographic Reference Ranges for Left Chamber Dimensions in Children and Adolescents: A Systematic Review.

Echocardiography plays a critical role in the assessment of cardiac disease. Important differences in echocardiographically derived cardiac chamber dimensions have been previously highlighted in different population groups in adult studies, but this has not been systematically studied in children, whose body size changes throughout childhood. The aim of this study was to review the distribution of available reference ranges for the left cardiac chamber dimensions in older children and adolescents. The following electronic data bases were searched: Medline, Embase and Web of Science were searched to identify studies which have established echocardiographic reference ranges of left heart parameters in children and adolescents from 1975 to December 2017. There was no geographical limitation. All results were imported into Endnote. Retrieved articles were screened and data extracted by two independent reviewers. A total of 4398 studies were retrieved, with 36 studies finally included in this review. 29 (81%) references were from North America and European (Caucasians) populations, with only one study each from Africa and South America. Two-dimensional and M-mode techniques were the most commonly used echocardiography techniques. There were methodological variations in techniques and normalisation of references. Comparison of selected cardiac measures showed significant differences for interventricular septal thickness among Black African, Indian, German and US American children. Available echocardiographic references cannot be generalised to all settings and therefore, there is need for locally relevant reference ranges. Africa and South America are particularly under-represented. Future studies should focus on developing comprehensive echocardiographic reference ranges for children from different racial backgrounds and should use standardised techniques

La relación personal en el tratamiento de la diversidad

El autor centra su aportación en diferentes características de los organismos vivos, para incorporarlas a las perspectivas interpretativas y operativas, y de los métodos actuales de intervención educativa. En el texto también se trata el enfoque positivo desde la dimensión técnica y no «voluntarista», teniendo en cuenta que los especialistas que adoptan la perspectiva del enfoque positivo dan mucha importancia al tema de la calidad de vida.L'autor centra la seva aportació en diferents característiques dels organismes vius, per incorporar- les a les perspectives interpretatives i operatives, i dels mètodes actuals d'intervenció educativa. Al text també es tracta l'enfocament positiu des de la seva dimensió tècnica i no «voluntarista», tenint en compte que els especialistes que adopten la perspectiva de l'enfocament positiu donen molta importància al tema de la qualitat de vida.The author focuses on the different characteristics of the alive organisms in order to include them into the interpretative and operative views of the current methods of educational intervention. He also deals with the positive focus, from the technical and «no voluntary» dimension, taking into account that those specialists having this kind of view do emphasize a lot on the quality of life issue

An Improved Implementation and Abstract Interface for Hybrid

Hybrid is a formal theory implemented in Isabelle/HOL that provides an interface for representing and reasoning about object languages using higher-order abstract syntax (HOAS). This interface is built around an HOAS variable-binding operator that is constructed definitionally from a de Bruijn index representation. In this paper we make a variety of improvements to Hybrid, culminating in an abstract interface that on one hand makes Hybrid a more mathematically satisfactory theory, and on the other hand has important practical benefits. We start with a modification of Hybrid's type of terms that better hides its implementation in terms of de Bruijn indices, by excluding at the type level terms with dangling indices. We present an improved set of definitions, and a series of new lemmas that provide a complete characterization of Hybrid's primitives in terms of properties stated at the HOAS level. Benefits of this new package include a new proof of adequacy and improvements to reasoning about object logics. Such proofs are carried out at the higher level with no involvement of the lower level de Bruijn syntax.Comment: In Proceedings LFMTP 2011, arXiv:1110.668

An applied framework for Positive Education

The increasing momentum of the Positive Psychology movement has seen burgeoning research in positive mental health and adaptive functioning; a critical question is how this knowledge can now be applied in real-world settings. Positive Education seeks to combine principles of Positive Psychology with best-practice teaching and with educational paradigms to promote optimal development and flourishing in the school setting. Interest in Positive Education continues to grow in line with increasing recognition of the important role played by schools in fostering wellbeing, and the link between wellbeing and academic success. To date, however, a framework to guide the implementation of Positive Education in schools has been lacking. This paper provides an overview of the Geelong Grammar School (GGS) Model for Positive Education, an applied framework developed over five years of implementing Positive Education as a whole-school approach in one Australian school. Explicit and implicit teaching in combination with school-wide practices target six wellbeing domains, including positive emotions, positive engagement, positive accomplishment, positive purpose, positive relationships, and positive health, underpinned by a focus on character strengths. The Model provides a structured pathway for implementing Positive Education in schools, a framework to guide evaluation and research, and a foundation for further theoretical discussion and development

A formalized general theory of syntax with bindings

We present the formalization of a theory of syntax with bindings that has been developed and refined over the last decade to support several large formalization efforts. Terms are defined for an arbitrary number of constructors of varying numbers of inputs, quotiented to alpha-equivalence and sorted according to a binding signature. The theory includes a rich collection of properties of the standard operators on terms, such as substitution and freshness. It also includes induction and recursion principles and support for semantic interpretation, all tailored for smooth interaction with the bindings and the standard operators

Gyrospun antimicrobial nanoparticle loaded fibrous polymeric filters

© 2016 The Authors. Published by Elsevier B.V. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).A one step approach to prepare hybrid nanoparticle embedded polymer fibres using pressurised gyration is presented. Two types of novel antimicrobial nanoparticles and poly (methylmethacrylate) polymer were used in this work. X-ray diffraction analysis of the nanoparticles revealed Ag, Cu and W are the main elements present in them. The concentration of the polymer solution and the nanoparticle concentration had a significant influence on the fibre diameter, pore size and morphology. Fibres with a diameter in the range of 6-20 ìm were spun using 20 wt% polymer solutions containing 0.1, 0.25 and 0.5 w% nanoparticles under 0.3 MPa working pressure and a rotational speed of 36000 rpm. Continuous, bead-free fibre morphologies were obtained for each case. The pore size in the fibres varied between 36-300 nm. Successful incorporation of the nanoparticles in polymer fibres was confirmed by energy dispersive x-ray analysis. The fibres were also gyrospun on to metallic disks to prepare filters which were tested for their antibacterial activity on a suspension of Pseudomonas aeruginosa. Nanoparticle loaded fibres showed higher antibacterial efficacy than pure poly(methylmethacrylate) fibres.8pÍuPeer reviewedFinal Published versio