Extragalactic Point Source Search in Five-year WMAP 41, 61 and 94 GHz Maps

We present the results of an extragalactic point source search using the five-year WMAP 41, 61 and 94 GHz (Q-, V- and W-band) temperature maps. This work is an extension of our point source search in the WMAP maps applying a CMB-free technique. An internal linear combination (ILC) map has been formed from the three-band maps, with the weights chosen to remove the CMB anisotropy signal as well as to favor a selection of flat-spectrum sources. We find 381 sources at the > 5 sigma level outside the WMAP point source detection mask in the ILC map, among which 89 are "new" (i.e., not present in the WMAP catalog). Source fluxes have been calculated and corrected for the Eddington bias. We have solidly identified 367 (96.3%) of our sources. The 1 sigma positional uncertainty is estimated to be 2'. The 14 unidentified sources could be either extended radio structure or obscured by Galactic emission. We have also applied the same detection process on simulated maps and found 364+/-21 detections on average. The recovered source distribution N(>S) agrees well with the simulation input, which proves the reliability of this method.Comment: 28 pages, 9 figures, 2 tables, accepted by Ap

Metabolic adaption of mucosal macrophages: Is metabolism a driver of persistence across tissues?

Macrophages play essential roles in tissue homeostasis, defense, and repair. Their functions are highly tissue-specific, and when damage and inflammation stimulate repopulation by circulating monocytes, the incoming monocytes rapidly acquire the same, tissue-specific functions as the previous, resident macrophages. Several environmental factors are thought to guide the functional differentiation of recruited monocytes, including metabolic pressures imposed by the fuel sources available in each tissue. Here we discuss whether such a model of metabolic determinism can be applied to macrophage differentiation across barrier sites, from the lung to the skin. We suggest an alternative model, in which metabolic phenotype is a consequence of macrophage longevity rather than an early driver of tissue-specific adaption

The interface between arts practice and research: Attitudes and perceptions of Australian artist-academics

Whilst an academic working in the arts may have been appointed as a consequence of artistic accomplishment and a capacity to teach, the research that underpins such work is an intrinsic part of its production and also needs to be recognised. In Australia, the ability of the artist-academic to translate research into a form that is respected and rewarded is an issue of contention. This paper gathers responses to this issue. Perceptions of and attitudes to creative work as research are canvassed alongside life decisions arising from those perceptions and attitudes. This research occurs in the context of a new Australian framework for the evaluation of research. This framework offers some recognition of the research that supports creative practice. Thus, the long-standing experience of compromise reported by the Australian artist-academics interviewed for this study are discussed alongside new policies that seek to construct methodologies for its amelioration

Arts practice as a site of knowledge/research: An Australian perspective of the artist in academia

Due, in part, to the previous lack of recognition for arts practice as research, artists working as academics in Australia have been active in a growing body of writings addressing different approaches to practice-led research. In February 2008 the Australian Federal Labor government announced Excellence for Research in Australia (ERA), a new research framework that formally recognizes the research component of many creative works. There is now formal recognition of both the practice itself, and of practice-led writing. This paper draws on interviews conducted prior to the implementation of ERA with eight artist-academics employed at Australian universities. The study sought participants’ views on their arts practice as research or a site of knowledge. The relationships and interactions between the work of the artist and the work of the academic were being constantly negotiated and emerged as integral to the recognition of practice as research. Participants’ views appeared to be shaped by the creative medium in which each worked, and while responses married with views in the literature, several new issues were identified. Findings suggest many ways of writing about and teaching the knowledge contained within the artistic process and product. This knowledge has particular value to the academy in different locations

The artistic practice-research-teaching (ART) nexus: Translating the information flow

This paper reports findings from interviews with fourteen Australian artist academics, who discuss the complex relationships between their Arts practice, their Research and their Teaching. We refer to this as the ART nexus because of the strong flow of information reported between these three activities. However, this information flow is not achieved without conflict. Conflict arises over the balance of time available and different mindsets required for differing activities, and there can be hesitation about analysing intuitive creative thought. The findings reveal ways in which information is ‘translated’ for different audiences including undergraduate and postgraduate students, who are both recipients of and contributors to the nexus. The article problematises the ART nexus in an attempt to offer greater insight into the ways in which individual artist academics teach through their arts practice and their research, within a university system that struggles to accommodate this breadth of endeavour

Artist acaemics: Performing the Australian research agenda

Despite the recent focus on creativity and innovation as the backbone of Western knowledge economies, the presence of the creative arts within universities remains problematic. Australian artist academics, who seek a balance between their artistic and academic lives, work within a government-directed research environment that is unable to quantify and, therefore to recognize, the value of creative research, yet which accepts the funded outcomes of post-graduate practice-based students. Using interview methodology, this study sought to unravel how artist academics from a variety of non-written creative disciplines perceive the relationships between their roles as artists, researchers and tertiary educators. Central to the discussions was the question of whether and how creative work constitutes legitimate research. Although this is an Australian case study, the findings have relevance to artist academics in many settings

Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer

The angular power spectrum estimator developed by Peebles (1973) and Hauser & Peebles (1973) has been modified and applied to the 2 year maps produced by the COBE DMR. The power spectrum of the real sky has been compared to the power spectra of a large number of simulated random skies produced with noise equal to the observed noise and primordial density fluctuation power spectra of power law form, with $P(k) \propto k^n$. Within the limited range of spatial scales covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq \ell \lsim 30, the best fitting value of the spectral index is $n = 1.25^{+0.4}_{-0.45}$ with the Harrison-Zeldovich value $n = 1$ approximately 0.5$\sigma$ below the best fit. For 3 \leq \ell \lsim 19, the best fit is $n = 1.46^{+0.39}_{-0.44}$. Comparing the COBE DMR $\Delta T/T$ at small $\ell$ to the $\Delta T/T$ at $\ell \approx 50$ from degree scale anisotropy experiments gives a smaller range of acceptable spectral indices which includes $n = 1$.Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended Postscript figures, COBE Preprint 94-0

Topological Defects in an Open Universe

(To appear in Nuclear Physics B Supplements Proceedings section) This talk will explore the evolution of topological defects in an open universe. The rapid expansion of the universe in an open model slows defects and suppresses the generation of CBR fluctuations at large angular scale as does the altered relationship between angle and length in an open universe. Defect models, when normalized to COBE in an open universe, predict a galaxy power spectrum consistent with the galaxy power spectrum inferred from the galaxy surveys and do not require an extreme bias. Neither defect models in a flat universe nor standard inflationary models can fit either the multipole spectrum or the power spectrum inferred from galaxy surveys.Comment: 11 pages and 4 figures, Elsevier Publisher's LaTeX, POP-54

Producing Mega-pixel CMB Maps from Differential Radiometer Data

A major goal of cosmology is to obtain sensitive, high resolution maps of the Cosmic Microwave Background (CMB) anisotropy. Such maps, as would be produced by the recently proposed Microwave Anisotropy Probe (MAP), will contain a wealth of primary information about conditions in the early universe. To mitigate systematic effects when observing the microwave background, it is desirable for the raw data to be collected in differential form: as a set of temperature differences between points in the sky. However, the production of large (mega-pixel) maps from a set of temperature differences is a potentially severe computational challenge. We present a new technique for producing maps from differential radiometer data that has a computational cost that grows in the slowest possible way with increasing angular resolution and number of map pixels. The required central processor (CPU) time is proportional to the number of differential data points and the required random access memory (RAM) is proportional to the number of map pixels. We test our technique, and demonstrate its feasibility, by simulating one year of a space-borne anisotropy mission.Comment: 8 pages Latex with 3 Postscript figures embedded using eps

The properties and tunable nature of electrochemically-grown peptide-based hydrogels at single microelectrodes

Microelectrodes possess enhanced mass transport properties which make them desirable over macroelectrodes in point-of-care electrochemical biosensing platforms. Due to their scale, microelectrode biosensors also face a heightened receptiveness to biofouling, often characterised by the nonspecific binding of large molecules and cells to the sensing layer or electrode surface. This ultimately prevents the biosensor from providing an accurate measure of a chemical target. Anti-fouling, semi-permeable membranes are employed to prevent biofouling at point-of-care biosensors. Recently, peptide-based supramolecular hydrogels have been considered as anti-fouling membranes which can encapsulate and immobilise sensing layers. A pH shift generated by the electrochemical oxidation of hydroquinone triggers the self-assembly of dissolved gelator molecules local to the electrode surface, and the peptide-based gelator molecules aggregate into fibre-like structures that entangle to form the gel in these localised acidic regions. This thesis first explores the extent to which Carb-Ala hydrogels can be tuned at single 25 μm diameter Pt disc microelectrodes under potentiostatic control. Altering the time and potential applied has allowed for the production of gels with different sizes and densities using the same stock gelator solution, identified by pairing optical microscopy (both in situ and ex situ) and electrochemical impedance spectroscopy techniques. In doing so, a dynamic process between gel assembly and disassembly has been demonstrated: the gels first undergo a loss in density before a collapse in structure, characterised by a gradual increase in transparency and a gradual increase in the diffusion coefficients of a ferro/ferricyanide redox probe. This process was first observed during continuous gel growth, likely caused by a shift in the dominance of gelator deprotonation and network disassembly (driven by bulk pH 8 gelator solution flux) over self-assembly (driven by proton generation via hydroquinone oxidation). The gels underwent a similar loss in density followed by structure collapse in buffered pH 4.3 and unbuffered pH 0 solutions, though the rate of gel loss was decreased in the lower pH conditions. The phenomenon was also shown not be exclusive to Carb-Ala, as electrochemical gels of a second peptide-gelator BrAV also underwent these changes on a similar timescale. These observations suggested that gel instability might be driven by a concentration gradient of weakly-bound gelator at the electrode surface and the bulk gelator-less solutions. Lastly, a simple use-case for these gels as enzyme immobilising layers in a 1st generation enzymatic biosensor is presented. To avoid enzyme leaching with the breakdown of gels, electropolymerisation of Carb-Ala post-gelation was utilised as a way of stabilising the preformed, tuned microscale gels. The resulting GOx/Carb-Ala polymer-functionalised glucose biosensors were capable of producing progressively greater signals in the presence of increasing concentrations of glucose (due to the electrochemical oxidation of the H2O2 produced by the enzymes), and the calibration curves of each electrode displayed characteristic Michaelis-Menten kinetics. The sensors possessed a biologically relevant linear calibration range of 0-4 mM, a maximum sensitivity of 189 ± 9 μM mM-1 cm2, a LOD of 0.33 mM, and a t1/2 of up to 44 days at 37 °C