Influence of crystal structure on charge carrier effective masses in BiFeO3_3

Ferroelectric-based photovoltaics have shown great promise as a source of renewable energy, thanks to their in-built charge separation capability, yet their efficiency is often limited by low charge carrier mobilities. In this work, we compare the photovoltaic prospects of various phases of the multiferroic material BiFeO$_3$ by evaluating their charge carrier effective masses using first-principles simulations. We identify a tetragonal phase with the promising combination of a large spontaneous polarisation and relatively light charge carriers. From a systematic study of the octahedral distortions present in BiFeO$_3$, we explain the relationship between structure and effective masses in terms of the changes to the orbital character and overlap at the band edges that result from changes in the geometry. The findings in this study provide some design principles to engineer desired effective masses in BiFeO$_3$ and similar materials through manipulation of their crystal structures in experimentally accessible ways.Comment: 12 pages, 10 figure

Speculative bubbles in Bitcoin markets? An empirical investigation into the fundamental value of Bitcoin

Amid its rapidly increasing usage and immense public interest the subject of Bitcoin has raised profound economic and societal issues. In this paper we undertake economic and econometric modelling of Bitcoin prices. As with many asset classes we show that Bitcoin exhibits speculative bubbles. Further, we find empirical evidence that the fundamental price of Bitcoin is zero

The life and health challenges of young Malaysian couples: results from a stakeholder consensus and engagement study to support non-communicable disease prevention

BACKGROUND: Malaysia faces burgeoning obesity and diabetes epidemics with a 250% and 88% increase respectively between 1996 and 2006. Identifying the health challenges of young adults in Malaysia, who constitute 27.5 % of the population, is critical for NCD prevention. The aim of the study was two-fold: (1) to achieve consensus amongst stakeholders on the most important challenge impacting the health of young adults, and (2) to engage with stakeholders to formulate a NCD prevention framework.METHODS: The Delphi Technique was utilised to achieve group consensus around the most important life and health challenges that young adults face in Malaysia. Subsequently, the results of the consensus component were shared with the stakeholders in an engagement workshop to obtain input on a NCD prevention framework.RESULTS: We found that life stress was a significant concern. It would seem that the apathy towards pursuing or maintaining a healthy lifestyle among young adults may be significantly influenced by the broader distal determinant of life stress. The high cost of living is suggested to be the main push factor for young working adults towards attaining better financial security to improve their livelihood. In turn, this leads to a more stressful lifestyle with less time to focus on healthier lifestyle choices.CONCLUSIONS: The findings highlight a pivotal barrier to healthier lifestyles. By assisting young adults to cope with daily living coupled with realistic opportunities to make healthier dietary choices, be more active, and less sedentary could assist in the development of NCD health promotion strategies<br/

Online prostate cancer screening decision aid for at-risk men: A randomized trial

Objective: This study examines the efficacy of an online decision aid (DA) for men with a family history of prostate cancer. Methods: Unaffected Australian men (40 - 79 years) with at least one affected relative completed the first online questionnaire, were randomized to read either the tailored DA (intervention) or nontailored information about prostate cancer screening (control), then completed a questionnaire postreading and 12 months later. The primary outcome was decisional conflict regarding prostate specific antigen (PSA) testing. The impact of the DA on longitudinal outcomes was analyzed by using random intercept mixed effects models. Logistic and linear regressions were used to analyze the impact of the DA on screening behavior and decision regret. Stage of decision-making was tested as a moderator for decisional conflict and decision regret. The frequency of online material access was recorded. Results: the DA had no effect on decisional conflict, knowledge, inclination toward PSA testing, accuracy of perceived risk, or screening behavior. However, among men considering PSA testing, those who read the DA had lower decision regret compared with men who read the control materials, β=.34 , p \u3c.001, 95% confidence interval (CI) = [.22, .53]. Conclusions: This is the first study to our knowledge to evaluate the uptake and efficacy of an online screening DA among men with a family history of prostate cancer. Men who were undecided about screening at baseline benefitted from the DA, experiencing less regret 12 months later. In relation to decisional conflict, the control materials may have operated as a less complex and equally informative DA

Preliminary Trials on juvenile Macrobrachium rosenbergii Production under modified Static 'Green water' Conditions

The methods of juvenile production of Udang Galah (Macrobrachium rosenbergii) have been documented by several workers (ling, 1969 .. Ling and Costello, 1976 .. Fujimura 7966, 1967, 1968, 1972 .. Fujimura and okomoto, 1970,. Sandifer etl.1976). The methods given by these workers involve intensive hatchery management such as frequent water change and cleaning of larval tanks to ensure good sanitation. Such a technique would involve wastage of sea water and at the same time is labour intensive. 'to overcome the above mentioned problems a study 'was conducted at the hatchery of the Faculty of Fisheries and marine Science, Serdang, to produce" Udang Galah" juveniles 'Without water change and by using «green water' at salinities 6~8°100 and 12-14% 0 respectively. Previous studies by Cohen et al. (1976) have conclusively shozon that (green water' is an efficient system to remove toxic metabolites such as ammonia from the culture medium. The 'green water' 'which mainly consists of unicellular algae such as Chlorella is produced by expos;'lg 'loater of salim'ty 6°(00 'Which contained Sarothcrodon mossambicus to sunlight (Fujimura

Integrating user-centred design in the development of a silent speech interface based on permanent magnetic articulography

Abstract: A new wearable silent speech interface (SSI) based on Permanent Magnetic Articulography (PMA) was developed with the involvement of end users in the design process. Hence, desirable features such as appearance, port-ability, ease of use and light weight were integrated into the prototype. The aim of this paper is to address the challenges faced and the design considerations addressed during the development. Evaluation on both hardware and speech recognition performances are presented here. The new prototype shows a com-parable performance with its predecessor in terms of speech recognition accuracy (i.e. ~95% of word accuracy and ~75% of sequence accuracy), but significantly improved appearance, portability and hardware features in terms of min-iaturization and cost

Approximability of Connected Factors

Finding a d-regular spanning subgraph (or d-factor) of a graph is easy by Tutte's reduction to the matching problem. By the same reduction, it is easy to find a minimal or maximal d-factor of a graph. However, if we require that the d-factor is connected, these problems become NP-hard - finding a minimal connected 2-factor is just the traveling salesman problem (TSP). Given a complete graph with edge weights that satisfy the triangle inequality, we consider the problem of finding a minimal connected $d$-factor. We give a 3-approximation for all $d$ and improve this to an (r+1)-approximation for even d, where r is the approximation ratio of the TSP. This yields a 2.5-approximation for even d. The same algorithm yields an (r+1)-approximation for the directed version of the problem, where r is the approximation ratio of the asymmetric TSP. We also show that none of these minimization problems can be approximated better than the corresponding TSP. Finally, for the decision problem of deciding whether a given graph contains a connected d-factor, we extend known hardness results.Comment: To appear in the proceedings of WAOA 201

Motivations and perceptions of community advisory boards in the ethics of medical research: the case of the Thai-Myanmar border

Background: Community engagement is increasingly promoted as a marker of good, ethical practice in the context of international collaborative research in low-income countries. There is, however, no widely agreed definition of community engagement or of approaches adopted. Justifications given for its use also vary. Community engagement is, for example, variously seen to be of value in: the development of more effective and appropriate consent processes; improved understanding of the aims and forms of research; higher recruitment rates; the identification of important ethical issues; the building of better relationships between the community and researchers; the obtaining of community permission to approach potential research participants; and, the provision of better health care. Despite these diverse and potentially competing claims made for the importance of community engagement, there is very little published evidence on effective models of engagement or their evaluation. Methods. In this paper, drawing upon interviews with the members of a Community Advisory Board on the Thai-Myanmar border, we describe and critically reflect upon an approach to community engagement which was developed in the context of international collaborative research in the border region. Results and conclusions. Drawing on our analysis, we identify a number of considerations relevant to the development of an approach to evaluating community engagement in this complex research setting. The paper also identifies a range of important ways in which the Community Advisory Board is in practice understood by its members (and perhaps by community members beyond this) to have morally significant roles and responsibilities beyond those usually associated with the successful and appropriate conduct of research. © 2014 Maung Lwin et al.; licensee BioMed Central Ltd

A Preliminary Study on Induced Spawning of the Catfish Clarias batrachus (Linnaeus) in Malaysia

Ten gravid Clarias batrachus females were administered with a single dose of common carp pituitary homogenate (CPR). Bifore injection, the eggs were light yellow and the diameter rangedfrom 0.94 mm to 1.08 mm. Ovulation occurred approximately 12 hours after the adminstration of CPR. The colour of the eggs turned brown and the diameter rangedfrom o. 99 mm to 1.27 mm. The fertilization rates rangedfrom 10-81%. The eggs hatched after about 30-36 hours of incubation at 26°C to 28°C. The hatching rates ranged from 13-67070