Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes

In [arXiv:0803.3259] the equations describing the parallel transport of orthonormal frames along timelike (spacelike) geodesics in a spacetime admitting a non-degenerate principal conformal Killing-Yano 2-form h were solved. The construction employed is based on studying the Darboux subspaces of the 2-form F obtained as a projection of h along the geodesic trajectory. In this paper we demonstrate that, although slightly modified, a similar construction is possible also in the case of null geodesics. In particular, we explicitly construct the parallel-transported frames along null geodesics in D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport along principal null directions in these spacetimes. Such directions coincide with the eigenvectors of the principal conformal Killing-Yano tensor. Finally, we show how to obtain a parallel-transported frame along null geodesics in the background of the 4D Plebanski-Demianski metric which admits only a conformal generalization of the Killing-Yano tensor.Comment: 17 pages, no figure

Steering protein adsorption at charged surfaces : electric fields and ionic screening

Protein adsorption at charged surfaces is a common process in the development of functional technological devices. Accurately reproducing the environment above the surface in simulations is essential for understanding how the adsorption process can be influenced and utilised. Here we present a simulation strategy that includes the electric field above the charged surface as well as the screening ions in solution, using standard molecular dynamics tools. With this approach we investigate the adsorption of Hen Egg White Lysozyme (HEWL) onto a model charged silica surface. We find that the screening effects of the ions slow down the adsorption process, giving the protein more time to find its optimal orientation as it adsorbs. Furthermore, we find that the concentrated ionic region directly above the surface helps to stabilise the protein structure in its adsorbed state. Together these effects imply that the adsorbed HEWL might retain its biological activity, with its active site exposed to solution rather than to the surface. Furthermore, this work shows how the steering effects of the electric field, coupled to the ionic screening, might be used to develop general strategies for surface functionalization through protein adsorption for technological applications

Private Native Forestry: Silviculture, Sustainability and Incentives for Vegetation Management

Timber supplies from public native forests have declined significantly in recent decades. Consequently, wood processors are increasingly dependent on private land to maintain their throughput of native species logs. In some regions of Australia, more than 50 per cent of native forest industry log supply comes from private property. There is concern that this increased demand brings with it the increased risk of high grading in private forests - repeated removal of only merchantable stock, leaving an increasing proportion of poor quality trees which may be detrimental to both future timber yields and habitat quality. Nevertheless, this market situation also represents a commercial opportunity for private landholders and some additional incentive for them to better manage their forests for long-term sustainability. However, this needs to be supported by a policy and regulatory framework that provides incentives for private forest owners to manage their forests sustainably. Environmental policy settings and broader economic drivers can over-ride this opportunity. A range of biodiversity/habitat sustainability indicators have been developed to gauge the impacts of clearing for agriculture and in some states, for forestry operations in native forests. In Australia, these have principally been developed with a focus on public land, but, as additional scrutiny is brought to bear on private landholders, they are increasingly focused on private native forestry (PNF). Implementation of indicators may increase both the direct costs and the constraints on private native forest managers. It seems likely that returns from timber production alone may be insufficient to ensure best practice silviculture in private native forests. Incentives, available to the landowner, which recognize the public environmental goods being provided by well managed forests, may be one solution to the problem. This will require some quantification of how alternative forest management systems impact on those 'public good' values. Others suggest that government price setting arrangements for public forest timber maintain artificially low prices which reduce private forest management incentives. This paper is a progress report on several linked projects funded through RIRDC JVAP, which field test sustainability indicators, investigate the tradeoffs between commercial timber production and habitat/biodiversity conservation and examine options for improved private native forest management through commercial incentives

Relative effects on stratospheric ozone of halogenated methanes and ethanes of social and industrial interest

Four atmospheric modeling groups have calculated relative effects of several halocarbons (chlorofluorocarbons (CFC's)-11, 12, 113, 114, and 115; hydrochlorofluorocarbons (HCFC's) 22, 123, 124, 141b, and 142b; hydrofluorocarbons (HFC's) 125, 134a, 143a, and 152a, carbon tetrachloride; and methyl chloroform) on stratospheric ozone. Effects on stratospheric ozone were calculated for each compound and normalized relative to the effect of CFC-11. These models include the representations for homogeneous physical and chemical processes in the middle atmosphere but do no account for either heterogeneous chemistry or polar dynamics which are important in the spring time loss of ozone over Antarctica. Relative calculated effects using a range of models compare reasonably well. Within the limits of the uncertainties of these model results, compounds now under consideration as functional replacements for fully halogenated compounds have modeled stratospheric ozone reductions of 10 percent or less of that of CFC-11. Sensitivity analyses examined the sensitivity of relative calculated effects to levels of other trace gases, assumed transport in the models, and latitudinal and seasonal local dependencies. Relative effects on polar ozone are discussed in the context of evolving information on the special processes affecting ozone, especially during polar winter-springtime. Lastly, the time dependency of relative effects were calculated

The Monstrous ‘White Theory Boy’: Symbolic Capital, Pedagogy and the Politics of Knowledge

This article presents a critical uncovering of the continued dominance of whiteness and maleness in processes and practices of knowledge formation. Tracking the figure of the ‘white theory boy’ or ‘dead white man’ across experiential accounts of theory, scholarship on canonicity, and pedagogical strategies, the article demonstrates his enduring authority in theoretical knowledge making and dissemination. Where this article moves somewhere different is its suggestion that a space of sympathy be extended to this hegemonic figure. Though the dominance of the ‘white theory boy’ undoubtedly perpetuates inequalities throughout social theoretic thought, it is necessary to locate a new method of tackling such ingrained problems. Though extending sympathy to the ‘white theory boy’ is perhaps initially counter-intuitive, my suggestion is that he does not hold the sort of monolithic power we might first assume. Bringing an intersectional analysis of gender, class, ‘race’ and ethnicity to bear on this figure, creates a space in which a more critical and fine-grained account of the relationship between power, knowledge, and social status can be uncovered. It is through extending this space of sympathy and mutual cooperation to ‘white theory boys’ that the practical and conceptual machinations of their power are further revealed. From here a more thorough dismantling of this power becomes possible

Theorizing black (African) transnational masculinities

Just as masculinity is crucial in the construction of nationhood, masculinity is also significant in the making and unmaking of transnational communities. This article focuses on how black African men negotiate and perform respectable masculinity in transnational settings such as the workplace, community and family. Moving away from conceptualizations of black transnational forms of masculinities as in perpetual crisis and drawing on qualitative data collected from members of the new African diaspora in London, the article explores the diverse ways notions of masculinity and gender identities are being challenged, re-affirmed and reconfigured. The article argues that men experience a loss of status as breadwinners and a rupture of their sense of masculine identity in the reconstruction of life in the diaspora. Conditions in the hostland, in particular, women's breadwinner status and the changing gender relations, threaten men’s ‘hegemonic masculinity’ and consequently force men to negotiate respectable forms of masculinity

Nontuberculous mycobacterial disease in children :epidemiology, diagnosis and management at a tertiary center

Background There are limited data on the epidemiology, diagnosis and optimal management of nontuberculous mycobacterial (NTM) disease in children. Methods Retrospective cohort study of NTM cases over a 10-year-period at a tertiary referral hospital in Australia. Results A total of 140 children with NTM disease, including 107 with lymphadenitis and 25 with skin and soft tissue infections (SSTIs), were identified. The estimated incidence of NTM disease was 0.6–1.6 cases / 100,000 children / year; no increasing trend was observed over the study period. Temporal analyses revealed a seasonal incidence cycle around 12 months, with peaks in late winter/spring and troughs in autumn. Mycobacterium-avium-complex accounted for most cases (77.8%), followed by Mycobacterium ulcerans (14.4%) and Mycobacterium marinum (3.3%). Polymerase chain reaction testing had higher sensitivity than culture and microscopy for acid-fast bacilli (92.0%, 67.2% and 35.7%, respectively). The majority of lymphadenitis cases underwent surgical excision (97.2%); multiple recurrences in this group were less common in cases treated with clarithromycin and rifampicin compared with clarithromycin alone or no anti-mycobacterial drugs (0% versus 7.1%; OR:0.73). SSTI recurrences were also less common in cases treated with two anti-mycobacterial drugs compared with one or none (10.5% versus 33.3%; OR:0.23). Conclusions There was seasonal variation in the incidence of NTM disease, analogous to recently published observations in tuberculosis, which have been linked to seasonal variation in vitamin D. Our finding that anti-mycobacterial combination therapy was associated with a reduced risk of recurrences in patients with NTM lymphadenitis or SSTI requires further confirmation in prospective trials