Surface spin dynamics of antiferromagnetically coupled frustrated triangular films

Results are presented for spin-wave dispersions in geometrically frustrated stacked triangular antiferromagnets with a thin film or semi-infinite geometry having either zero, easy-plane, or easy-axis anisotropy. Surface effects on the equilibrium spin configurations and excitation spectrum are investigated for the case of antiferromagnetically coupled films, serving to extend previous results on ferromagnetically coupled layers [E. Meloche et al., Phys. Rev. B 74, 094424 (2006)]. An operator equation of motion formalism is applied to systems which are quasi-one and quasi-two dimensional in character. In contrast to the case of ferromagnetically coupled films the new results show surface modes that are well separated in frequency from bulk excitations. Magnetic excitations in thin films with an even or an odd number of layers show qualitatively different behavior. These results are relevant for a wide variety of stacked triangular antiferromagnetics materials.Comment: 24 pages, 9 figure

A study of long range order in certain two-dimensional frustrated lattices

We have studied the Heisenberg antiferromagnets on two-dimensional frustrated lattices, triangular and kagome lattices using linear spin-wave theory. A collinear ground state ordering is possible if one of the three bonds in each triangular plaquette of the lattice becomes weaker or frustrated. We study spiral order in the Heisenberg model along with Dzyaloshinskii-Moriya (DM) interaction and in the presence of a magnetic field. The quantum corrections to the ground state energy and sublattice magnetization are calculated analytically in the case of triangular lattice with nearesr-neighbour interaction. The corrections depend on the DM interaction strength and the magnetic field. We find that the DM interaction stabilizes the long-range order, reducing the effect of quantum fluctuations. Similar conclusions are reached for the kagome lattice. We work out the linear spin-wave theory at first with only nearest-neighbour (nn) terms for the kagome lattice. We find that the nn interaction is not sufficient to remove the effects of low energy fluctuations. The flat branch in the excitation spectrum becomes dispersive on addition of furthet neighbour interactions. The ground state energy and the excitation spectrum have been obtained for various cases.Comment: 18 pages, 9 figure

Consumer perspectives on product lifetimes: a national study of lifetime satisfaction and purchasing factors

The extension of product lifetimes of consumer goods has the potential to encourage sustainable consumption, reduce carbon emissions and facilitate a transition to a circular economy. However, current understandings of consumer perspectives on product lifetimes are limited. This paper presents the findings of the first national study of consumer satisfaction with product lifetimes across an exhaustive range of consumer durables. The research was undertaken in the United Kingdom where consumer satisfaction and purchasing factors were studied across eighteen product categories. These product categories were devised from academic and market research undertaken at Nottingham Trent University. In total, 2,207 participants completed the survey and the sample profile was similar to the United Kingdom's population with respect to age and gender. The results indicate that consumers appear generally satisfied with the lifetimes of their products and suggest that efforts to extend product lifetimes should focus on developing business and policy options. However, participants also emphasised that longevity, reliability and guarantee length were important factors in their purchasing decisions. Consumer interest in these factors could indicate that lifetime labelling and the promotion of longer guarantees by manufacturers and retailers may offer pathways to reduce energy and material consumption associated with short-lived products, facilitating movement towards a low carbon circular economy

Consumer expectations of product lifetimes around the world: a review of global research findings and methods

This paper presents the findings of research to identify and evaluate current studies into consumer expectations of product lifetimes across durable goods. Following a literature review, studies were classified using a product categorisation scheme formulated at Nottingham Trent University and a product lifetime expectations typology adapted from Oguchi et al. (2016a) was developed. The results would appear to suggest that consumer expectations of product lifetimes are in decline, and that those in the United Kingdom appear to be lower than those in other parts of the world. However, identifying differences in consumer expectations of product lifetimes is hindered by the different methods employed in studies, as face-to-face interviews, and online, telephone and postal studies all have the potential to produce different results. Three key challenges to furthering research into consumer expectations of product lifetimes were identified: Product coverage, definitions of consumer expectations and sampling strategies. Only if these challenges can be addressed will researchers be able to draw meaningful conclusions on both personal and cultural trends in expected product lifetimes and make a positive contribution to addressing both material and social aspects of the circular economy

Properties of the Nearly Free Electron Superconductor Ag5Pb2O6 Inferred from Fermi Surface Measurements

We measured the Fermi surface of the recently discovered superconductor Ag5Pb2O6 via a de Haas-van Alphen rotation study. Two frequency branches were observed and identified with the neck and belly orbits of a very simple, nearly free electron Fermi surface. We use the observed Fermi surface geometry to quantitatively deduce superconducting properties such as the in-plane and out-of-plane penetration depths, the coherence length in the clean limit, and the critical field; as well as normal state properties such as the specific heat and the resistivity anisotropy.Comment: 2 pages, 1 figure, submitted to Physica C (M2S Proceedings

A Reformed Information Security Management System (R-ISMS)

An Information Security Management System (ISMS) specifies the instruments and methods that an administration/management level of an institution uses to comprehensibly manage the tasks and activities aimed at achieving information security. ISMS evolved as a systematic and structured approach to managing information following advances in IT infrastructure, services and applications so that they remain secure. While there are various implemented ISMS frameworks, researchers continually try to emphasize and increase human participation in ensuring information security. The aim of this research study is to develop an algorithm-based model to facilitate effective ISMS services for organizations. This algorithm-based ISMS model employed Information Technology General Controls (ITGC) technique as an expansion of the vistas of known ISMS frameworks, to improve information security control in organizations. The purpose of refinement is to make the frameworks more easily understood, implemented, and measured in organizations by stakeholders.Microsoft Office Visio 2010 software was used in designing the reformed model. Bactracking and Branch-and-bound algorithms were used in developing the model. The model utilises the above named methods to address the problem of inadequate management systems for information security. The results of this study showed that, with the level of usability, International Organization for Standardization (ISO) standards are more easily implemented and well recognized by stakeholders (top management, staff, suppliers, customers/clients, regulators) unlike the other security frameworks.  In conclusion, this study showed that R-ISMS is a customized algorithm model that assists organizations to enhance the ability in monitoring the performance of their activities, policies and procedures. Keywords:Information Security Management Systems (ISMSs), Reformed ISMS, International Organization for Standardization/International Electrotechnical Commission (ISO/IEC),  Backtracking / Branch-and-bound algorithms

Holes in the valence band of superconducting boron-doped diamond film studied by soft X-ray absorption and emission spectroscopy

Carbon- and boron-2$p$ states of superconducting and non-superconducting boron-doped diamond samples are measured using soft X-ray emission and absorption spectroscopy. For the superconducting sample, a large density of hole states is observed in the valence band in addition to the states in the impurity band. The hole states in the valence band is located at about 1.3 eV below the valence band maximum regardless of the doping level, which cannot be interpreted within a simple rigid band model. Present experimental results, combined with the first principles calculations, suggest that superconductivity is to be attributed to the holes in the valence band.Comment: 4 pages, 4 figure

Workplace fraud and theft in SMEs: evidence from the mobile telephone sector in Nigeria

Purpose - This study investigates employee fraud within small enterprises in the Nigerian mobile phone sector. It also seeks to understand the key factors that motivate employees to engage in fraudulent behaviours against their employers, and the consequences of these fraudulent behaviours on small businesses (SMEs) in Nigeria. Design/methodology/approach - The empirical study involves the use of quantitative research. Data was collected through structured questionnaires from 159 business owners, sales representatives, cashiers and suppliers. Frequency distribution, Percentages, Pearson correlation, and multiple regression analysis were used to analyse the collected data. Findings - The findings from this research shows a significant relationship between personal and organisational factors and employee theft. Particularly, organisational factors made the strongest positive contribution to employee theft. The research also revealed that employee theft had significant effects on employers but less significance on employees. In addition, the research revealed that many businesses did not have preventive measures against employee theft in their firms. Originality/Value – This study shows the relationship between different factors that could cause an employee to engage in fraudulent behaviours, particularly in SMEs in Nigeria

Consumers' expectations for product lifetimes of consumer durables

Product lifetimes are a relevant topic of discussion towards establishing a circular economy, particularly in terms of the reduction of environmental impacts by improving product longevity. Various researchers have developed models to estimate actual lifetimes and have reported case studies for some product categories (e.g. electrical and electronic equipment, and vehicles). However, actual lifetimes may not necessarily meet consumers' expectations. Therefore, an integration of the two perspectives—actual and expected product lifetimes—should prove helpful in optimizing product lifetimes. We proposed different definitions of expected product lifetimes from the consumer perspective and then investigated consumer expectations of the product lifetimes of consumer durables according to these definitions. Several types of EEE were examined as case studies, and questionnaire surveys were conducted. We found that exp ected lifetimes varied according to the definition used. Expected product life-times should be measured by using clearly defined terms to analyse the gaps between actual product lifetimes and consumer expectations