599 research outputs found

    An Aboriginal Australian Record of the Great Eruption of Eta Carinae

    Full text link
    We present evidence that the Boorong Aboriginal people of northwestern Victoria observed the Great Eruption of Eta ({\eta}) Carinae in the nineteenth century and incorporated the event into their oral traditions. We identify this star, as well as others not specifically identified by name, using descriptive material presented in the 1858 paper by William Edward Stanbridge in conjunction with early southern star catalogues. This identification of a transient astronomical event supports the assertion that Aboriginal oral traditions are dynamic and evolving, and not static. This is the only definitive indigenous record of {\eta} Carinae's outburst identified in the literature to date.Comment: Accepted in the Journal for Astronomical History & Heritage, Volume 13, Issue 3 (November, 2010). 9 Figures, 4 Table

    Flux calibration of the AAO/UKST SuperCOSMOS H-alpha Survey

    Full text link
    The AAO/UKST SuperCOSMOS Hα\alpha Survey (SHS) was, when completed in 2003, a powerful addition to extant wide-field surveys. The combination of areal coverage, spatial resolution and sensitivity in a narrow imaging band, still marks it out today as an excellent resource for the astronomical community. The 233 separate fields are available online in digital form, with each field covering 25 square degrees. The SHS has been the motivation for equivalent surveys in the north, and new digital Hα\alpha surveys now beginning in the south such as VPHAS+. It has been the foundation of many important discovery projects with the Macquarie/AAO/Strasbourg Hα\alpha planetary nebula project being a particularly successful example. However, the full potential of the SHS has been hampered by lack of a clear route to acceptable flux calibration from the base photographic data. We have determined the calibration factors for 170 individual SHS fields, and present a direct pathway to the measurement of integrated Hα\alpha fluxes and surface brightnesses for resolved nebulae detected in the SHS. We also include a catalogue of integrated Hα\alpha fluxes for >>100 planetary and other nebulae measured from the SHS, and use these data to show that fluxes, accurate to ±\pm 0.10 - 0.14 dex (∼\sim25-35 per cent), can be obtained from these fields. For the remaining 63 fields, a mean calibration factor of 12.0 counts pix−1^{-1} R−1^{-1} can be used, allowing the determination of reasonable integrated fluxes accurate to better than ±\pm0.2 dex (∼\sim50 per cent). We outline the procedures involved and the caveats that need to be appreciated in achieving such flux measurements. This paper forms a handy reference source that will significantly increase the scientific utility of the SHS.Comment: 14 pages, 12 figures, 2 tables (plus 7 pp. of supplementary online information). Version to appear in MNRA

    Geobase Information System Impacts on Space Image Formats

    Get PDF
    As Geobase Information Systems increase in number, size and complexity, the format compatability of satellite remote sensing data becomes increasingly more important. Because of the vast and continually increasing quantity of data available from remote sensing systems the utility of these data is increasingly dependent on the degree to which their formats facilitate, or hinder, their incorporation into Geobase Information Systems. To merge satellite data into a geobase system requires that they both have a compatible geographic referencing system. Greater acceptance of satellite data by the user community will be facilitated if the data are in a form which most readily corresponds to existing geobase data structures. The conference addressed a number of specific topics and made recommendations

    Elevated glutamatergic compounds in pregenual anterior cingulate in pediatric autism spectrum disorder demonstrated by 1H MRS and 1H MRSI.

    Get PDF
    Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy ((1)H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age, but with fewer males and higher IQ. In the ASD group in midline pACC, we found mean 17.7% elevation of glutamate + glutamine (Glx) (p<0.05) and 21.2% (p<0.001) decrement in creatine + phosphocreatine (Cr). We then performed a larger (26 subjects with ASD, 16 controls) follow-up study in samples now matched for age, gender, and IQ using proton magnetic resonance spectroscopic imaging ((1)H MRSI). Higher spatial resolution enabled bilateral pACC acquisition. Significant effects were restricted to right pACC where Glx (9.5%, p<0.05), Cr (6.7%, p<0.05), and N-acetyl-aspartate + N-acetyl-aspartyl-glutamate (10.2%, p<0.01) in the ASD sample were elevated above control. These two independent studies suggest hyperglutamatergia and other neurometabolic abnormalities in pACC in ASD, with possible right-lateralization. The hyperglutamatergic state may reflect an imbalance of excitation over inhibition in the brain as proposed in recent neurodevelopmental models of ASD

    Milky Way and Magellanic Cloud Surveys for Planetary Nebulae

    Get PDF
    Abstract. The recent on-line availability of large-scale, wide-field surveys of the Galaxy and Magellanic Clouds in several optical and near/mid-infrared passbands has provided unprecedented opportunities to refine selection techniques and eliminate contaminants in PN surveys. This has been coupled with new surveys offering improved detection rates via higher sensitivity and resolution. This will permit more extreme ends of the PN luminosity function to be explored and enable studies of under represented PN evolutionary states. Known PNe in our Galaxy and LMC have thus been significantly increased over the last few years due primarily to the advent of narrow-band imaging in important nebula lines such as Hα, [O iii] and [S iii]. These PNe are generally of lower surface brightness, larger angular extent, in more obscured regions and in later stages of evolution than those in most previous surveys. A more representative PN population for in-depth study is now available, particularly in the LMC where the known distance adds considerable utility for derived PN parameters. Future prospects for Galactic and LMC PNe research are briefly highlighted

    Multi-vehicle Control in a Strong Flowfield with Application to Hurricane Sampling

    Full text link
    A major obstacle to path-planning and formation-control algorithms in multi-vehicle systems are strong flows in which the ambient flow speed is greater than the vehicle speed relative to the flow. This challenge is espe-cially pertinent in the application of unmanned aircraft used for collecting targeted observations in a hurricane. The presence of such a flowfield may inhibit a vehicle from making forward progress relative to a ground-fixed frame, thus limiting the directions in which it can travel. Using a self-propelled particle model in which each particle moves at constant speed relative to the flow, this paper presents results for motion coordination in a strong, known flowfield. We present the particle model with respect to inertial and rotating reference frames and provide for each case a set of con-ditions on the flowfield that ensure trajectory feasibility. Results from the Lyapunov-based design of decentralized control algorithms are presented for circular, folium, and spirograph trajectories, which are selected for their potential use as hurricane sampling trajectories. The theoretical results are illustrated using numerical simulations in an idealized hurricane model. Nomenclature N Number of particles in the system k Particle index k = 1,..., N rk Position of k th particle with respect to inertial frame r̃k Position of k th particle with respect to rotating fram

    The Impact of Body Mass Index Upon the Efficacy of Adalimumab in Hidradenitis Suppurativa

    Get PDF
    Elevated BMI in Hidradenitis Suppurativa is associated with decreased response to Adalimumab therapy. BMI is proposed to segregate distinct disease subtypes. It remains unresolved whether a threshold BMI exists above which increased dosages may provide clinical benefit. Individual patient data from 578 PIONEER Phase 3 participants were analyzed. Descriptive, multivariable regression analysis and receiver operating characteristic (ROC) curves were calculated to assess the relationship between BMI and clinical outcome measures using R v3.5.3. Participants in the overweight and obese BMI category had reduced odds (58 and 67%, respectively) of achieving HiSCR [OR = 0.42 (95%CI −0.19, 0.91) p = 0.03], [OR = 0.33 (95%CI 0.16, 0.67) p = 0.002] compared to participants with BMI < 25. Reduction in AN count and IHS4 score was not significantly associated. ROC analysis did not reveal any cut off value predictive of treatment outcome. No correlation between BMI and baseline disease activity or covariate interactions were identified. These findings suggest BMI is a significant covariate in the setting of lower baseline disease activity, supporting the concept of disease heterogeneity and differential therapeutic response to Adalimumab

    SPITZER SAGE Observations of Large Magellanic Cloud Planetary Nebulae

    Get PDF
    We present IRAC and MIPS images and photometry of a sample of previously known planetary nebulae (PNe) from the SAGE survey of the Large Magellanic Cloud (LMC) performed with the Spitzer Space Telescope. Of the 233 known PNe in the survey field, 185 objects were detected in at least two of the IRAC bands, and 161 detected in the MIPS 24 micron images. Color-color and color-magnitude diagrams are presented using several combinations of IRAC, MIPS, and 2MASS magnitudes. The location of an individual PN in the color-color diagrams is seen to depend on the relative contributions of the spectral components which include molecular hydrogen, polycyclic aromatic hydrocarbons (PAHs), infrared forbidden line emission from the ionized gas, warm dust continuum, and emission directly from the central star. The sample of LMC PNe is compared to a number of Galactic PNe and found to not significantly differ in their position in color-color space. We also explore the potential value of IR PNe luminosity functions (LFs) in the LMC. IRAC LFs appear to follow the same functional form as the well-established [O III] LFs although there are several PNe with observed IR magnitudes brighter than the cut-offs in these LFs.Comment: 18 pages, 10 figures, 3 tables, to be published in the Astronomical Journal. Additional online data available at http://www.cfa.harvard.edu/irac/publications

    Observations of red-giant variable stars by Aboriginal Australians

    Full text link
    Aboriginal Australians carefully observe the properties and positions of stars, including both overt and subtle changes in their brightness, for subsistence and social application. These observations are encoded in oral tradition. I examine two Aboriginal oral traditions from South Australia that describe the periodic changing brightness in three pulsating, red-giant variable stars: Betelgeuse (Alpha Orionis), Aldebaran (Alpha Tauri), and Antares (Alpha Scorpii). The Australian Aboriginal accounts stand as the only known descriptions of pulsating variable stars in any Indigenous oral tradition in the world. Researchers examining these oral traditions over the last century, including anthropologists and astronomers, missed the description of these stars as being variable in nature as the ethnographic record contained several misidentifications of stars and celestial objects. Arguably, ethnographers working on Indigenous Knowledge Systems should have academic training in both the natural and social sciences.Comment: The Australian Journal of Anthropology (2018

    Spitzer IRAC observations of newly-discovered planetary nebulae from the Macquarie-AAO-Strasbourg H-alpha Planetary Nebula Project

    Full text link
    We compare H-alpha, radio continuum, and Spitzer Space Telescope (SST) images of 58 planetary nebulae (PNe) recently discovered by the Macquarie-AAO-Strasbo- urg H-alpha PN Project (MASH) of the SuperCOSMOS H-alpha Survey. Using InfraRed Array Camera (IRAC) data we define the IR colors of PNe and demonstrate good isolation between these colors and those of many other types of astronomical object. The only substantive contamination of PNe in the color-color plane we illustrate is due to YSOs. However, this ambiguity is readily resolved by the unique optical characteristics of PNe and their environs. We also examine the relationships between optical and MIR morphologies from 3.6 to 8.0um and explore the ratio of mid-infrared (MIR) to radio nebular fluxes, which is a valuable discriminant between thermal and nonthermal emission. MASH emphasizes late evolutionary stages of PNe compared with previous catalogs, enabling study of the changes in MIR and radio flux that attend the aging process. Spatially integrated MIR energy distributions were constructed for all MASH PNe observed by the GLIMPSE Legacy Project, using the H-alpha morphologies to establish the dimensions for the calculations of the Midcourse Space Experiment (MSX), IRAC, and radio continuum (from the Molonglo Observatory Synthesis Telescope and the Very Large Array) flux densities. The ratio of IRAC 8.0-um to MSX 8.3-um flux densities provides a measure of the absolute diffuse calibration of IRAC at 8.0 um. We independently confirm the aperture correction factor to be applied to IRAC at 8.0um to align it with the diffuse calibration of MSX. The result agrees with the recommendations of the Spitzer Science Center and with results from a parallel study of HII regions. These PNe probe the diffuse calibration of IRAC on a spatial scale of 9-77 arcsec.Comment: 48 pages, LaTeX (aastex), incl. 18 PostScript (eps) figures and 3 tables. Accepted by Astrophysical Journa
    • …
    corecore