Cracking the Polyketide Code

Polyketides, natural products from microorganisms, have been a main source of antibiotics. Understanding the 'programming' of the enzymes that produce these complex molecules has opened a new field of drug discover

Enhancing students’ learning through simulation: dealing with diverse, large cohorts

As the field of health care simulation matures, new questions about appropriate pedagogy are emerging which present challenges to research and practices. This has implications for how we investigate and deliver effective simulations, how we conceive effectiveness, and how we make decisions about investment in simulation infrastructure. In this article, we explore two linked challenges that speak to these wider concerns: student diversity and large cohorts. We frame these within contemporary simulation practices and offer recommendations for research and practice that will account for students' varying cultural expectations about learning and clinical practice in the Australian context

Herschel SPIRE Fourier Transform Spectrometer: Calibration of its Bright-source Mode

The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two detector setting modes: (a) a nominal mode, which is optimized for observing moderately bright to faint astronomical targets, and (b) a bright-source mode recommended for sources significantly brighter than 500 Jy, within the SPIRE FTS bandwidth of 446.7-1544 GHz (or 194-671 microns in wavelength), which employs a reduced detector responsivity and out-of-phase analog signal amplifier/demodulator. We address in detail the calibration issues unique to the bright-source mode, describe the integration of the bright-mode data processing into the existing pipeline for the nominal mode, and show that the flux calibration accuracy of the bright-source mode is generally within 2% of that of the nominal mode, and that the bright-source mode is 3 to 4 times less sensitive than the nominal mode.Comment: 15 pages, 16 figures, accepted for publication in Experimental Astronom

Observing Extended Sources with the \Herschel SPIRE Fourier Transform Spectrometer

The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and the source's light profile taken into account. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to \theta_{D} ~ 17". We demonstrate how the angular size of an extended source can be estimated using the difference between the sub-spectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959<\nu<989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2", which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.Comment: Accepted for publication by A&