Ab-initio spin dynamics applied to nanoparticles: canted magnetism of a finite Co chain along a Pt(111) surface step edge

In order to search for the magnetic ground state of surface nanostructures we extended first principles adiabatic spin dynamics to the case of fully relativistic electron scattering. Our method relies on a constrained density functional theory whereby the evolution of the orientations of the spin-moments results from a semi-classical Landau-Lifshitz equation. This approach is applied to a study of the ground state of a finite Co chain placed along a step edge of a Pt(111) surface. As far as the ground state spin orientation is concerned we obtain excellent agreement with the experiment. Furthermore we observe noncollinearity of the atom-resolved spin and orbital moments. In terms of magnetic force theorem calculations we also demonstrate how a reduction of symmetry leads to the existence of canted magnetic states.Comment: 4 pages, ReVTeX + 3 figures (Encapsulated Postscript), submitted to PR

Characterization of the spore surface and exosporium proteins of Clostridium sporogenes; implications for Clostridium botulinum group I strains.

Clostridium sporogenes is a non-pathogenic close relative and surrogate for Group I (proteolytic) neurotoxin-producing Clostridium botulinum strains. The exosporium, the sac-like outermost layer of spores of these species, is likely to contribute to adhesion, dissemination, and virulence. A paracrystalline array, hairy nap, and several appendages were detected in the exosporium of C. sporogenes strain NCIMB 701792 by EM and AFM. The protein composition of purified exosporium was explored by LC-MS/MS of tryptic peptides from major individual SDS-PAGE-separated protein bands, and from bulk exosporium. Two high molecular weight protein bands both contained the same protein with a collagen-like repeat domain, the probable constituent of the hairy nap, as well as cysteine-rich proteins CsxA and CsxB. A third cysteine-rich protein (CsxC) was also identified. These three proteins are also encoded in C. botulinum Prevot 594, and homologues (75-100% amino acid identity) are encoded in many other Group I strains. This work provides the first insight into the likely composition and organization of the exosporium of Group I C. botulinum spores

Gravitational wave detection using pulsars: status of the Parkes Pulsar Timing Array project

The first direct detection of gravitational waves may be made through observations of pulsars. The principal aim of pulsar timing array projects being carried out worldwide is to detect ultra-low frequency gravitational waves (f ~ 10^-9 to 10^-8 Hz). Such waves are expected to be caused by coalescing supermassive binary black holes in the cores of merged galaxies. It is also possible that a detectable signal could have been produced in the inflationary era or by cosmic strings. In this paper we review the current status of the Parkes Pulsar Timing Array project (the only such project in the Southern hemisphere) and compare the pulsar timing technique with other forms of gravitational-wave detection such as ground- and space-based interferometer systems.Comment: Accepted for publication in PAS

A possible signature of cosmic neutrino decoupling in the nHz region of the spectrum of primordial gravitational waves

In this paper we study the effect of cosmic neutrino decoupling on the spectrum of cosmological gravitational waves (GWs). At temperatures T>>1 MeV, neutrinos constitute a perfect fluid and do not hinder GW propagation, while for T<<1 MeV they free-stream and have an effective viscosity that damps cosmological GWs by a constant amount. In the intermediate regime, corresponding to neutrino decoupling, the damping is frequency-dependent. GWs entering the horizon during neutrino decoupling have a frequency f ~ 1 nHz, corresponding to a frequency region that will be probed by Pulsar Timing Arrays (PTAs). In particular, we show how neutrino decoupling induces a spectral feature in the spectrum of cosmological GWs just below 1 nHz. We briefly discuss the conditions for a detection of this feature and conclude that it is unlikely to be observed by PTAs.Comment: 11 pages, 2 figures. V2: References Adde

Cancergazing? CA125 and post-treatment surveillance in advanced ovarian cancer.

Post-treatment surveillance of advanced ovarian cancer involves regular testing of asymptomatic patients using the CA125 test. This practice is based on a rationale that is not supported by evidence from clinical trials. This paper aims to stimulate critical reflection concerning the effect of investigative tests on clinical decisions and interactions, and the experience of illness, particularly in the context of advanced malignant disease. Drawing on the idea of the “medical gaze”, and building on previous health communication research, we present an analysis of in-depth interviews and psychometric tests collected in a prospective study of 20 Australian women with advanced ovarian cancer conducted between 2006 and 2009. We describe the demands placed on patients by the use of the CA125 test, some hazards it creates for decision-making, and some of the test’s subjective benefits. It is widely believed that the CA125 test generates anxiety among patients, and the proposed solution is to educate women more about the test. We found no evidence that anxiety was a problem requiring a response over and above existing services. We conclude that the current debate is simplistic and limited. Focussing on patient anxiety does not account for other important effects of post-treatment surveillance, and educating patients about the test is unlikely to mitigate anxiety because testing is part of a wider process by which patients become aware of a disease that – once it has relapsed – will certainly kill them in the near future.National Health and Medical Research Council Project Grant number 40260

Beyond evidence: reappraising use of CA-125 as post-therapy surveillance for ovarian cancer

omen who have completed primary chemotherapy for ovarian cancer commonly have serial assessment of the serum tumour marker cancer antigen 125 (CA-125).1 This practice has been based on the proven utility of CA-125 in diagnostic algorithms and as a marker of response to therapy. Serial CA-125 assessment is also used because there is evidence that in women who have completed treatment for ovarian cancer, the serum CA-125 rises 2–6 months before symptoms or signs of relapse develop. The assumption underlying this and other similar studies is that serial monitoring of CA-125 would enable early diagnosis and treatment of relapse. This would thus lead to delay or reduction of cancer-related symptoms, psychological reassurance and, in theory, improved survival. Some studies have suggested that CA-125 may have some benefit in post-treatment surveillance. However, many others have demonstrated that although a rising CA-125 level is highly predictive of relapse, surveillance monitoring of CA-125 levels after remission from primary chemotherapy confers little benefit over standard clinical examination and does not improve duration of survival or quality of life

The perils of a vanishing cohort: A study of social comparisons by women with advanced ovarian cancer

Objective: To examine the role social comparisons play in the experience of ovarian cancer patients and to consider the implications this may have for provision of supportive care services for ovarian cancer patients. Methods: We conducted a longitudinal qualitative study of women with advanced ovarian cancer in Sydney, Australia. Semi-structured interviews were conducted with women with advanced ovarian cancer over a period of 2.5 years. Social comparisons made by 13 study participants in 33 interviews were extracted and analysed using coding categories based on social comparison theory. Results: Participants favoured downward contrasts and lateral comparisons and avoided downward identifications, upward contrasts and upward identifications. Participants expressed a preference for avoiding contact with ovarian cancer patients, for the company of “normal” others, for normalizing information and information that facilitated upward identifications. Conclusions: We suggest that social comparisons made by women with ovarian cancer are influenced by specific clinical factors associated with their diagnosis – in particular their status as a member of a “vanishing cohort” – and argue for further research examining the specific comparison needs and preferences of patients with advanced disease and types of cancer with poor prognoses. Practice implications: These findings raise questions about uniform approaches to the provision of cancer care and suggest that further research may be required to ensure that interventions are appropriately tailored to the supportive care needs of patients with different types and stages of disease. KEYWORDS Cancer; Oncology; Ovarian neoplasms; Social comparison theory; Social support; Self-help groupsNational Health & Medical Research Council Project Grant 40260

Agent-based homeostatic control for green energy in the smart grid

With dwindling non-renewable energy reserves and the adverse effects of climate change, the development of the smart electricity grid is seen as key to solving global energy security issues and to reducing carbon emissions. In this respect, there is a growing need to integrate renewable (or green) energy sources in the grid. However, the intermittency of these energy sources requires that demand must also be made more responsive to changes in supply, and a number of smart grid technologies are being developed, such as high-capacity batteries and smart meters for the home, to enable consumers to be more responsive to conditions on the grid in real-time. Traditional solutions based on these technologies, however, tend to ignore the fact that individual consumers will behave in such a way that best satisfies their own preferences to use or store energy (as opposed to that of the supplier or the grid operator). Hence, in practice, it is unclear how these solutions will cope with large numbers of consumers using their devices in this way. Against this background, in this paper, we develop novel control mechanisms based on the use of autonomous agents to better incorporate consumer preferences in managing demand. These agents, residing on consumers' smart meters, can both communicate with the grid and optimise their owner's energy consumption to satisfy their preferences. More specifically, we provide a novel control mechanism that models and controls a system comprising of a green energy supplier operating within the grid and a number of individual homes (each possibly owning a storage device). This control mechanism is based on the concept of homeostasis whereby control signals are sent to individual components of a system, based on their continuous feedback, in order to change their state so that the system may reach a stable equilibrium. Thus, we define a new carbon-based pricing mechanism for this green energy supplier that takes advantage of carbon-intensity signals available on the internet in order to provide real-time pricing. The pricing scheme is designed in such a way that it can be readily implemented using existing communication technologies and is easily understandable by consumers. Building upon this, we develop new control signals that the supplier can use to incentivise agents to shift demand (using their storage device) to times when green energy is available. Moreover, we show how these signals can be adapted according to changes in supply and to various degrees of penetration of storage in the system. We empirically evaluate our system and show that, when all homes are equipped with storage devices, the supplier can significantly reduce its reliance on other carbon-emitting power sources to cater for its own shortfalls. By so doing, the supplier reduces the carbon emission of the system by up to 25% while the consumer reduces its costs by up to 14.5%. Finally, we demonstrate that our homeostatic control mechanism is not sensitive to small prediction errors and the supplier is incentivised to accurately predict its green production to minimise costs