On equivocation

I offer an analysis of equivocation which shows it not to be a fallacy. One who equivocates does not make a logical error but an epistemological one

Berkeley's "esse is percipi" and Collier's "simple" argument

Almost all who write on Collier note a striking similarity between a short passage in his Clavis Universalis and the famous claim that esse is percipi in Berkeley's Principles. This essay explores that similarity in more detail than has been done before. The comparison forces us to address an issue about the nature of passivity in Berkeley's theory of mind. Two interpretations consistent with the text are offered and one is favoured on the grounds that it makes some of Berkeley's arguments more plausible. The idealisms of Berkeley and Collier are shown to have a common source

The enhancement of ferromagnetism in uniaxially stressed diluted magnetic semiconductors

We predict a new mechanism of enhancement of ferromagnetic phase transition temperature $T_c$ in uniaxially stressed diluted magnetic semiconductors (DMS) of p-type. Our prediction is based on comparative studies of both Heisenberg (inherent to undistorted DMS with cubic lattice) and Ising (which can be applied to strongly enough stressed DMS) models in a random field approximation permitting to take into account the spatial inhomogeneity of spin-spin interaction. Our calculations of phase diagrams show that area of parameters for existence of DMS-ferromagnetism in Ising model is much larger than that in Heisenberg model.Comment: Accepted for publication in Phys. Rev.

Modelling trade offs between public and private conservation policies

To reduce global biodiversity loss, there is an urgent need to determine the most efficient allocation of conservation resources. Recently, there has been a growing trend for many governments to supplement public ownership and management of reserves with incentive programs for conservation on private land. At the same time, policies to promote conservation on private land are rarely evaluated in terms of their ecological consequences. This raises important questions, such as the extent to which private land conservation can improve conservation outcomes, and how it should be mixed with more traditional public land conservation. We address these questions, using a general framework for modelling environmental policies and a case study examining the conservation of endangered native grasslands to the west of Melbourne, Australia. Specifically, we examine three policies that involve: i) spending all resources on creating public conservation areas; ii) spending all resources on an ongoing incentive program where private landholders are paid to manage vegetation on their property with 5-year contracts; and iii) splitting resources between these two approaches. The performance of each strategy is quantified with a vegetation condition change model that predicts future changes in grassland quality. Of the policies tested, no one policy was always best and policy performance depended on the objectives of those enacting the policy. This work demonstrates a general method for evaluating environmental policies and highlights the utility of a model which combines ecological and socioeconomic processes.Comment: 20 pages, 5 figure

Power dissipation in nanoscale conductors: classical, semi-classical and quantum dynamics

Modelling Joule heating is a difficult problem because of the need to introduce correct correlations between the motions of the ions and the electrons. In this paper we analyse three different models of current induced heating (a purely classical model, a fully quantum model and a hybrid model in which the electrons are treated quantum mechanically and the atoms are treated classically). We find that all three models allow for both heating and cooling processes in the presence of a current, and furthermore the purely classical and purely quantum models show remarkable agreement in the limit of high biases. However, the hybrid model in the Ehrenfest approximation tends to suppress heating. Analysis of the equations of motion reveals that this is a consequence of two things: the electrons are being treated as a continuous fluid and the atoms cannot undergo quantum fluctuations. A means for correcting this is suggested

Action, Knowledge and Embodiment in Berkeley and Locke

Embodiment is a fact of human existence which philosophers should not ignore. They may differ to a great extent in what they have to say about our bodies, but they have to take into account that for each of us our body has a special status, it is not merely one amongst the physical objects, but a physical object to which we have a unique relation. While Descartes approached the issue of embodiment through consideration of sensation and imagination, it is more directly reached by consideration of action and agency: whenever we act upon the world, we act by moving our bodies. So if we can understand what an immaterialist such as Berkeley thinks about agency, we will have gone a fair way to understanding what he thinks about embodiment. §1 discusses a recent flurry of articles on the subject of Berkeley’s account of action. I choose to present Berkeley as a causal-volitional theorist (realist) not because I think it is the uniquely correct interpretation of the texts, but because I find it more philosophically interesting as a version of immaterialism. In particular, it raises the possibility of a substantive account of human embodiment which is completely unavailable to the occasionalist. §2 articulates an apparent philosophical problem for Berkeley qua causal-volitional theorist and show that Locke was aware of a related problem and had a solution of which Berkeley would have known. §3 distinguishes two interpretations of Berkeley’s famous denial of blind agency–as the assertion of a weak representational condition or a strong epistemic one–and provide evidence that there was a well-established debate about blind powers in the seventeenth century which took the metaphor of blindness as indicating an epistemic rather than merely representational failing. What remains to do in §4 is to consider whether Berkeley, with his own peculiar commitments, could in fact accept this account of agency

Suppression of carrier induced ferromagnetism by composition and spin fluctuations in diluted magnetic semiconductors

We suggest an approach to account for spatial (composition) and thermal fluctuations in "disordered" magnetic models (e.g. Heisenberg, Ising) with given spatial dependence of magnetic spin-spin interaction. Our approach is based on introduction of fluctuating molecular field (rather than mean field) acting between the spins. The distribution function of the above field is derived self-consistently. In general case this function is not Gaussian, latter asymptotics occurs only at sufficiently large spins (magnetic ions) concentrations $n_i$. Our approach permits to derive the equation for a critical temperature $T_c$ of ferromagnetic phase transition with respect to the above fluctuations. We apply our theory to the analysis of influence of composition fluctuations on $T_c$ in diluted magnetic semiconductors (DMS) with RKKY indirect spin-spin interaction.Comment: 6 pages, 2 figure

Outdoor workers and sun protection strategies: Two case study examples in Queensland, Australia

Introduction: Outdoor workers are at risk of developing skin cancer because they are exposed to high levels of harmful ultraviolet radiation. The Outdoor Workers Sun Protection Project investigated sun protection strategies for high risk outdoor workers in rural and regional Australia. Methods: Fourteen workplaces (recruitment rate 37%) across four industries in rural and regional Queensland, Australia were recruited to the OWSPP. In 2011–2012, data were collected using pre- and post-intervention interviews and discussion groups. This article presents two workplaces as case study examples. Results: The flat organisational structure of workplace 1 supported the implementation of the Sun Safety Action Plan (SSAP), whilst the hierarchical organisational nature of workplace 2 delayed implementation of the SSAP. Neither workplace had an existing sun protection policy but both workplaces adopted one. An effect related to the researchers’ presence was seen in workplace 1 and to a lesser degree in workplace 2. Overt reciprocity was seen between management and workers in workplace 1 but this was not so evident in workplace 2. In both workplaces, the role of the workplace champion was pivotal to SSAP progression. Conclusions: These two case studies highlight a number of contextually bound workplace characteristics related to sun safety. These issues are (1) the structure of workplace, (2) policy, (3) an effect related to the researchers’ presence, (4) the workplace champion and (5) reciprocity. There are several recommendations from this article. Workplace health promotion strategies for sun safety need to be contextualised to individual workplaces to take advantage of the strengths of the workplace and to build capacity

Superlattice formed by quantum-dot sheets: density of states and IR absorption

Low-energy continuous states of electron in heterosrtucture with periodically placed quantum-dot sheets are studied theoretically. The Green's function of electron is governed by the Dyson equation with the self-energy function which is determined the boundary conditions at quantum-dot sheets with weak damping in low-energy region. The parameters of superlattice formed by quantum-dot sheets are determined using of the short-range model of quantum dot. The density of states and spectral dependencies of the anisotropic absorption coefficient under mid-IR transitions from doped quantum dots into miniband states of superlattice strongly depend on dot concentration and on period of sheets. These dependencies can be used for characterization of the multi-layer structure and they determine parameters of different optoelectronic devices exploiting vertical transport of carriers through quantum-dot sheets.Comment: 7 pages and 5 figure

A tight binding model for water

We demonstrate for the first time a tight binding model for water incorporating polarizable anions. A novel aspect is that we adopt a "ground up" approach in that properties of the monomer and dimer only are fitted. Subsequently we make predictions of the structure and properties of hexamer clusters, ice-XI and liquid water. A particular feature, missing in current tight binding and semiempirical hamiltonians, is that we reproduce the almost two-fold increase in molecular dipole moment as clusters are built up towards the limit of bulk liquid. We concentrate on properties of liquid water which are very well rendered in comparison with experiment and published density functional calculations. Finally we comment on the question of the contrasting densities of water and ice which is central to an understanding of the subtleties of the hydrogen bond