The electronic band structure and optical properties of boron arsenide

We compute the electronic band structure and optical properties of boron arsenide using the relativistic quasiparticle self-consistent $GW$ approach, including electron-hole interactions through solution of the Bethe-Salpeter equation. We also calculate its electronic and optical properties using standard and hybrid density functional theory. We demonstrate that the inclusion of self-consistency and vertex corrections provides substantial improvement in the calculated band features, in particular when comparing our results to previous calculations using the single-shot $GW$ approach and various DFT methods, from which a considerable scatter in the calculated indirect and direct band gaps has been observed. We find that BAs has an indirect gap of 1.674 eV and a direct gap of 3.990 eV, consistent with experiment and other comparable computational studies. Hybrid DFT reproduces the indirect gap well, but provides less accurate values for other band features, including spin-orbit splittings. Our computed Born effective charges and dielectric constants confirm the unusually covalent bonding characteristics of this III-V system.Comment: 7 pages, 3 figure

A part, not apart from nature: The IUBS ethics commission - An overview of a journey from 2000-2012

This paper explores the development of the way in which humans interact and have interacted with their natural environment. In particular, it places this within the context of the International Union of Biological Science's Ethics Commission, a body established in 2007 to develop ethical norms for bioethics and environmental ethics. The Ethics Commission grew out of what was the IUBS Bioethics Committee - the name change being dictated by confusion about the meaning of the term bioethics - which had recently been captured by the medical profession and was increasingly applied to medical practice alone. The new IUBS Ethics Commission (ICE) had a public presence as the International Centre for Environmental and Bioethics (ICEB), the web page of which was a vehicle to facilitate the provision and dissemination of ideas, news, concerns and case studies about the ethical management of the biosphere. In July 2012, the commission ceased to exist as a stand-alone entity. The reasons for this closure were varied; ranging from a lack of interest, to a belief that the commission was no longer required, to an inability or a lack of willingness to be personally involved in environmental ethics. The ICE is nonetheless still an important part of IUBS - currently as a subcommittee within the Biological Education Commission. The paper finishes with a review of the achievements of the commission over the last few years, and assesses where the critical ethical issues in biological sciences are likely to arise in the next decade: continued environmental degradation, increased intellectual theft and scientific obfuscation

On the pedagogy of ethics in engineering degrees: rationale, imperatives and internationalization

Nations that are signatory to the Washington Accord (1989) accept that the teaching of ethics, in a professional context, is mandatory for undergraduate engineering curricula. The inclusion of ethics, in otherwise very tight curricula, is due to the changing role of engineering; in particular it reflects a greater public awareness of the effects of engineering processes. On the basis of this, it follows that engineers are required to demonstrate transparently responsible practice in the knowledge that they are indeed accountable for their actions. In most countries, this requirement is embodied in legislation. The teaching of ethics to engineering undergraduates is a relatively new concept. This paper provides an overview of one methodology, the 'full submergence' technique, wherein engineers are challenged to respond to ethical conundrums in a high intensity project-based, block course. Over the last decade, this model has been successfully used in four countries

Creationism and intelligent design: a critique

No abstrac

Equilibrium point defect and charge carrier concentrations in a material determined through calculation of the self-consistent Fermi energy

A concise procedure to determine the self-consistent Fermi energy and defect and carrier concentrations in an extended crystalline system is presented. It is assumed that the formation enthalpies of a set of variously charged point defects in thermodynamic equilibrium are known, as well as the density of electronic states in the defect-free system. By applying the constraint of overall charge neutrality, the self-consistent Fermi energy is determined using an iterative searching routine. The procedure is incorporated within a Fortran code ‘SC-FERMI’: the input consists of the defect formation energies, density of sites where they can form, and the degeneracy of each charge state; the material band gap; and the calculated density of states of the pristine system. The output is the self-consistent Fermi energy, the total concentrations of each defect as well as the concentration of its individual charge states, and the free carrier concentrations. Furthermore, the procedure facilitates fixing the concentration of one or more defects and determining the resulting self-consistent Fermi energy and concentrations of other defects (performed using the related code ‘FROZEN-SC-FERMI’), thus modelling ‘frozen-in’ defects which may form by kinetic, rather than thermodynamic, processes. One can fix the total concentration or the concentration of a particular charge state; it is also possible to introduce new defects with a fixed concentration, but here the charge state must be specified. The background theory is discussed in some detail, and the operation of the program is demonstrated by some examples. Program summary: Program Title: SC-FERMI Program Files doi: http://dx.doi.org/10.17632/dh3hjdf4fc.1 Licensing provisions: MIT license Programming language: FORTRAN 90 Nature of problem: To determine the self-consistent Fermi energy and equilibrium defect and carrier concentrations given a set of point defect formation energies in a crystalline system, assuming the constraint of charge neutrality. Solution method: The concentrations of each defect in each charge state are calculated, as are the free carrier concentrations. These concentrations are functions of the Fermi energy. The code, using an iterative search algorithm, determines the Fermi energy that satisfies the charge neutrality constraint (the self-consistent Fermi energy). The defect and carrier concentrations at that Fermi energy are then reported, as well as the Fermi energy itself. Restrictions: Thermodynamic equilibrium is assumed. The defect formation enthalpies and electronic density of states of the pristine system must be known. Additional comments: The concentrations of defects can be fixed to a particular value, thus modelling ‘frozen-in’ defects formed by e.g. kinetic processes. This procedure is facilitated by the related program, FROZEN-SC-FERMI, which is identical to SC-FERMI apart from the additional defect concentration fixing routine

The barnacle and the building: a modern morality tale

A rare and almost complete barnacle fossil, previously described on the basis of two isolated shell fragments, was recently exposed in a limestone block on the outer wall of Melbourne's Old Magistrates' Courts in Victoria, Australia. These courts comprise one of the oldest and grandest buildings in Melbourne and because of this they have a heritage listing. As heritage-listed buildings are protected from alteration by law, and as removal of the fossil would be deemed "alteration", official permission had to be obtained to extract the specimen. This paper discusses the processes involved with extraction of a unique specimen from a protected building and provides an overview of the palaeontological significance of the fossil. Consideration is given to the likely fate of a fossil of this nature, situated a little below eye level on a busy city street, if it was left in situ; finally, the implications of designating a holotype from material removed from a building are assessed

The ongoing evolution of humanness: perspectives from Darwin to de Chardin

The nature of humanness is discussed from observations made by Aristotle in 4th-century Greece, through to those of Charles Darwin, Teilhard de Chardin and William Shakespeare. Attempts to define humanness upon a narrow range of criteria, as some have tried, is argued as flawed, for humanness is more elusive than a single or a new demonstrated phenomena. The path that Darwin pursued in determining the place of humans in nature in his book The Descent of Man, and Selection in Relation to Sex is assessed from a 19th century perspective; the difficulties he faced, both personally and with the broader public, are reviewed and then evaluated in a modern context. Darwin's thesis adheres to scientific principles, and is debated, defended and later verified on these principles. This is somewhat at variance to the approach adopted by the priest-scientist de Chardin a century later in his major work, The Phenomenon of Man-in which an attempt is made to reconcile a deep Christian faith with science. De Chardin scores well from a theological viewpoint, but fails on scientific grounds as his thesis moves beyond the realms of empiricism into mysticism. Surprisingly, de Chardin's predicament of a future wherein human evolution enters a new stage of consciousness through the noosphere (an invisible layer of thought encompassing the globe) has been partially realised through the worldwide web, although the nature of the web is almost certainly not what de Chardin might have anticipated, or desired. Science too fails to answer all, particularly the nature of Go

Ovulaster protodecimae, n. sp. (Echinoidea, Spatangoida) and associated epifauna (Cirripedia, Verrucidae) from the Danian of Northeastern Italy

A new species of echinoid, Ovulaster protodecimae, is described from the Danian Scaglia Rosa Formation outcropping in the Venetian Prealps (Southern Alps, northeastern Italy). The new species belonging to the order Spatangoida, is very distinctive because of its inflated, almost triangular test, the high-positioned peri-proct and the plate arrangement on the oral face. This is the first report of teh genus Ovulaster in the Danian of Italy and the first description of an echinoid from the Early Palaeocene of Italy. One test has an epifauna of the sessile verrucid barnacle Verruca sp. cf. V. prisca Bosquet, 1854, attached on all except the oral surface

Biomechanical asymmetries and joint loading in elite rowers

Rowing is a technical sport which requires a high skill level in order to optimise performance and reduce the risk of injury. Previous studies investigating the biomechanics of rowing technique and performance have focussed on two-dimensional lumbar-pelvic kinematics as well as more detailed three-dimensional descriptions of the lower extremity. However, limited research has examined lower limb asymmetries during rowing, with the majority of studies focussing on the action of a single leg. This study aims to quantify lower limb asymmetries during ergometer rowing, and the effect that asymmetries might have on the dynamics of the lumbar-pelvic joint, a commonly injured area in rowers, and subsequent performance. Kinematic asymmetries of the lower limbs were quantified using an electro-magnetic motion capture system. Symmetry of foot force production was also examined through custom force measuring footplates, with the design and output of these being developed and refined as part of this project. Inter-segmental loading of the lower limb and lumbar-pelvic joints were estimated with a five-segment inverse dynamics model, which utilised foot force and kinematic data as inputs. A final aim was to examine the effect of changing foot stretcher height on rowing performance and technique from a biomechanical perspective. The results indicate that rowing is in fact an asymmetrical activity, with significant bilateral differences identified at the footplates. From a movement perspective knee and hip joints were bilaterally asymmetrical, with hip range of motion asymmetries significantly associated with lumbar-pelvic flexion in the sagittal plane. Inter-segmental joint moments were not influenced by the presence of foot force asymmetries. However, they were influenced by increased rowing intensity. Large lumbar-pelvic extension moments were present during the rowing stroke, and these increased with respect to stroke rate. This is unlikely to be a measure of greater performance, as corresponding increases in performance measures such as foot and handle force were not observed. In fact, it may be an indicator of technique decline at higher work rates, as larger peak lumbar-pelvic moments occurred alongside increases in lumbar-pelvic flexion and loading of the seat – both of which are considered deleterious to performance. Therefore, rowers may be at greater risk of developing lower back pain when training at high intensities. A performance intervention, which involved raising the height of the foot-stretchers, was found to have little positive effect on the horizontal forces measured at the feet. In addition, there was a negative influence on stroke length and lumbar-pelvic posture. From a coaching perspective these results provide information regarding athlete set-up and their immediate implications on rowing performance. These studies have shown that elite rowers demonstrate biomechanical asymmetries of the lower limbs, and these could negatively influence the dynamics of the lumbar-pelvic joint and predispose them to low back pain. High intensity rowing and increases in foot stretcher height were also seen to increase lumbar-pelvic flexion through the rowing stroke. Key kinematic characteristics of the lower limbs which positively influence force production were also identified, thus providing rowing coaches with important biomechanical insight into performance optimisation and reduction of injury risk.Open Acces

In pursuit of the biological imperative an intergenerational approach to biological justice

This paper analyses the relationships between ethics and biology - particularly within the context of the Earth's degrading biosphere. We assess the manner in which humans have valued, and should value past and future human generations - from rational perspectives and as consequence of natural justice. We argue that life on Earth is more than likely unique within the universe, and that as a consequence of this, there is a duty for humans to exercise greater environmental stewardship. On the basis of this, the moral obligations that we have to future generations and ultimately future environments are debated, then confirmed. We conclude with a new biological imperative, in which it is asserted that in nature, justice is inter-temporal and must embrace all life found in the Earth's biosphere