Identification of putative regulatory signals including the HAP1 binding site in the upstream sequence of the Aspergillus nidulans cytochrome c gene (cycA).

We speculate that a HAP1-like protein, similar to those which regulate oxygen transcriptional activation of many yeast respiratory genes, will probably also regulate the A. nidulans cytochrome c (cycA) gene. As part of a study to investigate the significance of a putative HAP1 (Haem Activator Protein) binding site in the regulatory region of the cycA gene, routine sequencing revealed an error in the published sequence (Raitt et al. 1994 Mol. Gen. Genet. 242: 17-22). Examination of the corrected sequence, including RT-PCR analysis of cycA mRNA, showed that an extra intron was present, and that the published translational start site was incorrect. This meant that the putative HAP1-binding site proposed by Raitt et al. could not be a regulatory element. However, further sequence analysis of the upstream sequence of the corrected cycA gene revealed putative regulatory signals, including possible HAP1 binding sites which are a closer match to recently reported yeast consensus sequences (Ha et al. 1996 Nucl. Acids Res. 24: 1453-1459)

LSST optical beam simulator

We describe a camera beam simulator for the LSST which is capable of illuminating a 60mm field at f/1.2 with realistic astronomical scenes, enabling studies of CCD astrometric and photometric performance. The goal is to fully simulate LSST observing, in order to characterize charge transport and other features in the thick fully depleted CCDs and to probe low level systematics under realistic conditions. The automated system simulates the centrally obscured LSST beam and sky scenes, including the spectral shape of the night sky. The doubly telecentric design uses a nearly unit magnification design consisting of a spherical mirror, three BK7 lenses, and one beam-splitter window. To achieve the relatively large field the beam-splitter window is used twice. The motivation for this LSST beam test facility was driven by the need to fully characterize a new generation of thick fully-depleted CCDs, and assess their suitability for the broad range of science which is planned for LSST. Due to the fast beam illumination and the thick silicon design [each pixel is 10 microns wide and over 100 microns deep] at long wavelengths there can be effects of photon transport and charge transport in the high purity silicon. The focal surface covers a field more than sufficient for a 40x40 mm LSST CCD. Delivered optical quality meets design goals, with 50% energy within a 5 micron circle. The tests of CCD performance are briefly described.Comment: 9 pages, 9 figure

The geothermal world videogame: An authentic, immersive videogame used to teach observation skills needed for exploration

Interviews with geothermal professionals have identified geothermal concepts (i.e. knowledge) and skill sets that entry-level geologists commonly lack when beginning a career in the geothermal energy sector. To help address these issues, an authentic and immersive 3D free-roaming videogame called ‘The GeoThermal World’ was designed and piloted in 2012 at the University of Canterbury to teach undergraduate students about geothermal fieldwork and resource exploration. An experiment was carried out to compare students’ learning experiences in a real fieldwork activity at Orakei Korako to learning experiences in the virtual setting of the videogame. Both settings were designed with the same outcomes in mind: to provide the students with a level of background knowledge and operating procedures to do basic geothermal fieldwork. Several datasets were collected to characterize the students learning and to allow us to compare their overall experiences and perceptions of the tasks in different settings. In both activities, we aimed to teach the students how to observe, characterize and record geologic information at a hot spring. Preliminary results indicate that both settings are successful at teaching geothermal concepts with some strengths and weaknesses identified in both. However, the settings seem to be complementary to one another. Hence, ideally, field teaching experiences as a part of the undergraduate geology curriculum could be supplemented by digital or virtual experiences. This may cut down on the time required to ‘skill-up’ new entry-level geologists who may be lacking geothermal-specific field knowledge and skills. Further development of ‘The GeoThermal World’ will allow us to refine the authenticity and create more complex virtual geothermal settings and challenges

Chemical NOx budget in the upper troposphere over the tropical South Pacific

The chemical NOx budget in the upper troposphere over the tropical South Pacific is analyzed using aircraft measurements made at 6-12 km altitude in September 1996 during the Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM) Tropics A campaign. Chemical loss and production rates of NOx along the aircraft flight tracks are calculated with a photochemical model constrained by observations. Calculations using a standard chemical mechanism show a large missing source for NOx; chemical loss exceeds chemical production by a factor of 2.4 on average. Similar or greater NOx budget imbalances have been reported in analyses of data from previous field studies. Ammonium aerosol concentrations in PEM-Tropics A generally exceeded sulfate on a charge equivalent basis, and relative humidities were low (median 25% relative to ice). This implies that the aerosol could be dry in which case N2O5 hydrolysis would be suppressed as a sink for NOx. Suppression of N2O5 hydrolysis and adoption of new measurements of the reaction rate constants for NO2 + OH + M and HNO3 + OH reduces the median chemical imbalance in the NOx budget for PEM-Tropics A from 2.4 to 1.9. The remaining imbalance cannot be easily explained from known chemistry or long-range transport of primary NOx and may imply a major gap in our understanding of the chemical cycling of NOx in the free troposphere. Copyright 2000 by the American Geophysical Union

Laser-controlled fluorescence in two-level systems

The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited- state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markers, these ranging from quantum dots to green fluorescence protein. Expressions are presented for the laser-controlled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively. © 2010 American Chemical Society

Adsorbate site determination with the scanning tunneling microscope: C₂H₄ on Cu{110}

Scanning tunneling microscopy at T=4 K has been used to determine directly the binding site of a molecule chemisorbed on a metal surface, namely, ethene on Cu〈110〉, by simultaneous imaging of the adsorbate and the underlying lattice. The molecule is found to bond in the short bridge site on the close-packed rows with its C-C axis oriented in the 〈110〉 direction