Observations of red-giant variable stars by Aboriginal Australians

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

Identification of the Red Supergiant Progenitor of Supernova 2005cs: Do the Progenitors of Type II-P Supernovae Have Low Mass?

The stars that end their lives as supernovae (SNe) have been directly observed in only a handful of cases, due mainly to the extreme difficulty in identifying them in images obtained prior to the SN explosions. Here we report the identification of the progenitor for the recent Type II-plateau (core-collapse) SN 2005cs in pre-explosion archival images of the Whirlpool Galaxy (M51) obtained with the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). From high-quality ground-based images of the SN from the Canada-France-Hawaii Telescope, we precisely determine the position of the SN and are able to isolate the SN progenitor to within 0".04 in the HST/ACS optical images. We further pinpoint the SN location to within 0".005 from HST/ACS ultraviolet images of the SN, confirming our progenitor identification. From photometry of the SN progenitor obtained with the pre-SN ACS images, and also limits to its brightness in pre-SN HST/NICMOS images, we infer that the progenitor is a red supergiant star of spectral type K0--M3, with initial mass 7--9 Msun. We also discuss the implications of the SN 2005cs progenitor identification and its mass estimate. There is an emerging trend that the most common Type II-plateau SNe originate from low-mass supergiants 8--15 Msun.Comment: Submitted to ApJ. A high resolution version can be found at http://astron.berkeley.edu/~weidong/sn05cs.p

A realistic assessment of methods for extracting gene/protein interactions from free text

Background: The automated extraction of gene and/or protein interactions from the literature is one of the most important targets of biomedical text mining research. In this paper we present a realistic evaluation of gene/protein interaction mining relevant to potential non-specialist users. Hence we have specifically avoided methods that are complex to install or require reimplementation, and we coupled our chosen extraction methods with a state-of-the-art biomedical named entity tagger. Results: Our results show: that performance across different evaluation corpora is extremely variable; that the use of tagged (as opposed to gold standard) gene and protein names has a significant impact on performance, with a drop in F-score of over 20 percentage points being commonplace; and that a simple keyword-based benchmark algorithm when coupled with a named entity tagger outperforms two of the tools most widely used to extract gene/protein interactions. Conclusion: In terms of availability, ease of use and performance, the potential non-specialist user community interested in automatically extracting gene and/or protein interactions from free text is poorly served by current tools and systems. The public release of extraction tools that are easy to install and use, and that achieve state-of-art levels of performance should be treated as a high priority by the biomedical text mining community

A unified model for age-velocity dispersion relations in Local Group galaxies: Disentangling ISM turbulence and latent dynamical heating

We analyze age-velocity dispersion relations (AVRs) from kinematics of individual stars in eight Local Group galaxies ranging in mass from Carina ($M_{*} \sim 10^{6}$) to M31 ($M_{*} \sim 10^{11}$). Observationally the $\sigma$ vs. stellar age trends can be interpreted as dynamical heating of the stars by GMCs, bars/spiral arms, or merging subhalos; alternatively the stars could have simply been born out of a more turbulent ISM at high redshift and retain that larger velocity dispersion till present day - consistent with recent IFU studies. To ascertain the dominant mechanism and better understand the impact of instabilities and feedback, we develop models based on observed SFHs of these Local Group galaxies in order to create an evolutionary formalism which describes the ISM velocity dispersion due to a galaxy's evolving gas fraction. These empirical models relax the common assumption that the stars are born from gas which has constant velocity dispersion at all redshifts. Using only the observed SFHs as input, the ISM velocity dispersion and a mid-plane scattering model fits the observed AVRs of low mass galaxies without fine tuning. Higher mass galaxies above $M_{vir} > 10^{11}$ need a larger contribution from latent dynamical heating processes (for example minor mergers), in excess of the ISM model. Using the SFHs we also find that supernovae feedback does not appear to be a dominant driver of the gas velocity dispersion compared to gravitational instabilities - at least for dispersions $\sigma \gtrsim 25$ km/s. Together our results point to stars being born with a velocity dispersion close to that of the gas at the time of their formation, with latent dynamical heating operating with a galaxy mass-dependent efficiency. These semi-empirical relations may help constrain the efficiency of feedback and its impact on the physics of disk settling in galaxy formation simulations

The delay-time distribution of type-Ia supernovae from Sloan II

We derive the delay-time distribution (DTD) of type-Ia supernovae (SNe Ia) using a sample of 132 SNe Ia, discovered by the Sloan Digital Sky Survey II (SDSS2) among 66,000 galaxies with spectral-based star-formation histories (SFHs). To recover the best-fit DTD, the SFH of every individual galaxy is compared, using Poisson statistics, to the number of SNe that it hosted (zero or one), based on the method introduced in Maoz et al. (2011). This SN sample differs from the SDSS2 SN Ia sample analyzed by Brandt et al. (2010), using a related, but different, DTD recovery method. Furthermore, we use a simulation-based SN detection-efficiency function, and we apply a number of important corrections to the galaxy SFHs and SN Ia visibility times. The DTD that we find has 4-sigma detections in all three of its time bins: prompt (t < 420 Myr), intermediate (0.4 2.4 Gyr), indicating a continuous DTD, and it is among the most accurate and precise among recent DTD reconstructions. The best-fit power-law form to the recovered DTD is t^(-1.12+/-0.08), consistent with generic ~t^-1 predictions of SN Ia progenitor models based on the gravitational-wave induced mergers of binary white dwarfs. The time integrated number of SNe Ia per formed stellar mass is N_SN/M = 0.00130 +/- 0.00015 Msun^-1, or about 4% of the stars formed with initial masses in the 3-8 Msun range. This is lower than, but largely consistent with, several recent DTD estimates based on SN rates in galaxy clusters and in local-volume galaxies, and is higher than, but consistent with N_SN/M estimated by comparing volumetric SN Ia rates to cosmic SFH.Comment: MNRAS, in pres

DDO 216-A1: A Central Globular Cluster in a Low-luminosity Transition-type Galaxy

United States. National Aeronautics and Space Administration (HST GO-13768)United States. National Aeronautics and Space Administration (AST-1517226)United States. National Aeronautics and Space Administration (HST-AR-12836)United States. National Aeronautics and Space Administration (HST-AR-13888)United States. National Aeronautics and Space Administration (HST-AR-13896

The increasing importance of sustainability for building ownership

Purpose &mdash; This study seeks to investigate the degree to which energy efficiency is incorporated into office building refurbishment and capital expenditure with the emphasis placed on a cost-benefit analysis from the owner&rsquo;s perspective. Design/methodology/approach &ndash; In order to develop a research framework, a thorough literature review was conducted of three disciplines being construction technology, building refurbishment and property management. The study identifies differences between varying levels of capital expenditure to ensure an existing building is more energy efficient, with the emphasis placed on the cost of implementation and the potential for tenants to acknowledge the increased energy efficiency via higher rents. Findings &ndash; Office buildings have been identified as a contributor to global warming during the construction phase, however during the building lifecycle there is a greater contribution to CO2 omissions. Whilst various building designs and construction techniques have evolved to improve energy efficiency, the focus has largely been placed on new buildings where it is easier to incorporate change and innovative approaches. However, the proportion of new buildings constructed each year is relatively small in comparison to existing building stock, which requires regular capital expenditure to maintain and attract new tenants within a competitive marketplace. Practical implications &ndash; The increasing importance of energy efficiency affects the office market in a variety of different ways. Originality/value &ndash; This paper identifies important links between the environment and the built environment, and the implications for office building owners

Supernovae and their host galaxies. I. The SDSS DR8 database and statistics

(Abridged) In this first paper of a series, we report the creation of large and well-defined database that combines extensive new measurements and a literature search of 3876 supernovae (SNe) and their 3679 host galaxies located in the sky area covered by the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). This database should be much larger than previous ones, and should contain a homogenous set of global parameters of SN hosts, including morphological classifications and measures of nuclear activity. The measurements of apparent magnitudes, diameters (D25), axial ratios (b/a), and position angles (PA) of SN host galaxies were made using the images extracted from the SDSS g-band. For each host galaxy, we analyzed RGB images of the SDSS to accurately measure the position of its nucleus to provide the SDSS name. With these images, we also provide the host galaxy's morphological type, and note if it has a bar, a disturbed disk, and whether it is part of an interacting or merging system. In addition, the SDSS nuclear spectra were analyzed to diagnose the central power source of the galaxies. Special attention was paid to collect accurate data on the spectroscopic classes, coordinates, offsets of SNe, and heliocentric redshifts of the host galaxies. The creation of this large database will help to better understand how the different types of SNe are correlated with the properties of the nuclei and global physical parameters of the host galaxies, and minimize possible selection effects and errors that often arise when data are selected from different sources and catalogs.Comment: 20 pages, 15 figures, 7 table

Human factors in the design of sustainable built environments

Scientific research provides convincing evidence that climate change is having significant impacts on many aspects of life. In the built-environment domain, regulatory requirements are pushing the challenges of environmental, economic, and social sustainability at the core of the professional agenda, although the aims of carbon reduction and energy conservation are frequently given a priority over occupants' comfort, well-being, and satisfaction. While most practitioners declare to embrace sustainability as a driver of their professional approach, a general lack of integrated creative and technical skills hinders the design of buildings centred on articulate and comprehensive sustainability goals, encompassing, other than energy criteria, also human-centred and ethical values founded on competent and informed consideration of the requirements of the site, the programme, and the occupants. Built environments are designed by humans to host a range of human activities. In response, this article aims to endorse a sustainable approach to design founded on the knowledge arising from scholarly and evidence-based research, exploring principles and criteria for the creation and operation of human habitats that can respond to energy and legislative demands, mitigate their environmental impacts, and adapt to new climate scenarios, while elevating the quality of experience and delight to those occupying them