293 research outputs found
Near-side supernovae driven winds from the Large Magellanic Cloud
No full textMassive amounts of gaseous material are being ejected from the nearby Large Magellanic Cloud galaxy (LMC). With the LMC at only one Milky Way diameter away, we use this excellent opportunity to explore the ejected materials cycle in detail. The star-forming lifetime of a galaxy is dependent on both the gas supply of the galaxy and the galactic processes that occur within. Therefore, it is essential to study this wind in detail to understand the properties that will influence the LMCs evolution and the surrounding environment. We have combined ground-based and space-based observations to (1) map the near-side galactic wind of the LMC, (2) determine the morphology and extent of this gaseous outflow and (3) estimate a mass for the outflow. Understanding the properties of this galactic wind will provide invaluable information about galaxy evolution and surrounding environments, galactic feedback, and the LMCs possible influence on the Milky Way
Star-formation activity in low-mass disk galaxies
No full textInteraction between galaxies is of critical importance to the growth and evolution of galaxies. Due to the lack of studies on interactions between low-mass galaxies, it is still uncertain that how low-mass galaxies evolve during an interacting procedure. This investigation will explore how the internal star-formation activities of low-mass disk galaxies are influenced by the outer environment. The interaction-induced enhancement of star formation rate in diverse galaxy systems will be examined. This work presented here is the first attempt to systematically study the evolution of low-mass disk galaxies, it is also a pioneer of a statistical study on low-mass interacting galaxy systems. This investigation is based on data from the fourth-generation Sloan Digital Sky Survey (SDSS- IV) / Mapping Nearby Galaxies at Apache Point Observatory (MaNGA)
Gliding swifts attain laminar flow over rough wings
No full textSwifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13%) of their total area during glides that maximize flight distance and duration—similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation) before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance
Author Gender Representation at Audio Engineering Conferences - An Anonymised Dataset
No full textThis repository contains the author gender dataset (as a comma-delimited .csv file) associated with the paper entitled 'The Impact of Gender on Conference Authorship in Audio Engineering: Analysis Using a New Data Collection Method', published in the IEEE Transactions Special Issue on Increasing the Socio-Cultural Diversity of Electrical and Computer Engineering and Related Fields. Available at: dx.doi.org/10.1109/TE.2018.2814613. Please cite both the paper and dataset if used. Visualisation is available at: http://tibbakoi/github.io/aesgender.
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The dataset was produced using a novel method which used self-identified pronouns, therefore allowing for as many groups as necessary to describe the population.
A list of authors was generated from conference proceedings.
An email was sent to each author to acquire their pronoun.
If no email was available/no response was received, a pronoun was acquired from a biography.
If no biography was available, a pronoun was inferred from traditional gender markers and gender presentation.
If no gender marker/photograph was available, the entry was labelled as 'Information Unavailable'. For brevity, the label 'Unknown' is used in the paper.
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The columns in the dataset are as follows:
ID: unique identifier of entry
Pronoun: pronoun of entry
Position (abs): numerical absolute position within author list for entry
Position (relative): relative position within author list for entry (either First, Last, or Middle)
Single/multi-author: whether the publication for that entry has a single author or has multiple authors (single author publications are excluded from author position analysis)
Conference: Full conference name of entry
Topic: Topic of conference of entry, taken from conference name
Year: Year of conference of entry
Type: Type of publication for that entry as listed on the online conference proceedings
Grouped Type: Grouping of publication types for that entry for easier analysis due to inconsistencies in online conference proceedings (groups are: workshop, poster, paper, panel, keynote, invited speaker, invited paper, demo)
Inc. for author pos?: True/False as to whether to include the entry for analysis over author position (included types are: paper, invited paper, poster as these have meaningful author orders)
Inc. for single/multi-author?: True/False as to whether to include the entry for analysis over single/multi author (includes types are: paper, invited paper, poster as these have meaningful author orders)
Invited paper status: Grouping of the types to allow statistical analysis over invited vs non-invited types (invited types are: invited speaker, invited paper, keynote, panel. Non-invited types are: poster, paper, demo, workshop)
NB: Some grouping of the data is required as online conference proceedings are not always consistent (Column 10). Some labelling of the data is required to determine which entries to include in certain types of analysis (Columns 11-13).
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This dataset is distributed in the hopes that it will prove useful under the Creative Commons Attribution 4.0, with no warranty; or the implied warranty of merchantability or fitness for a particular problem.
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Dataset curated by: Kat Young and Michael Lovedee-Turner at the Audio Lab, Dept. of Electronic Engineering, University of York.
Contact: [email protected], [email protected]</p
Galactic winds of the Large Magellanic Cloud
No full textIn the Large Magellanic Cloud (LMC), galaxy interactions have triggered intense star formation throughout its disk. Using UV Hubble Space Telescope (HST) absorption-line observations towards an AGN and a LMC disk star projected only 100 pc away, we find gaseous outflows that are relatively symmetric in kinematics and properties on both sides of the galaxy's disk. These results when combined with previous studie provide compelling evidence that stellar activity drives a global, large-scale wind that permeates from its entire disk. As the LMC is the only galaxy where the connection between the stellar activity and galactic feedback can be fully resolved, these results provide insight into the effects of stellar feedback in further away galaxies
Galactic winds of the Large Magellanic Cloud
No full textIn the Large Magellanic Cloud (LMC), galaxy interactions have triggered intense star formation throughout its disk. Using UV Hubble Space Telescope (HST) absorption-line observations towards an AGN and a LMC disk star projected only 100 pc away, we find gaseous outflows that are relatively symmetric in kinematics and properties on both sides of the galaxy's disk. These results—when combined with previous studies—provide compelling evidence that stellar activity drives a global, large-scale wind that permeates from its entire disk. As the LMC is the only galaxy where the connection between the stellar activity and galactic feedback can be fully resolved, these results provide insight into the effects of stellar feedback in further away galaxies
Kat River revisited
No full textThere is a paucity of oral-history works on Kat River. Likewise, although various histories of Kat River/Stockenstrom exist, few have focused on the forced removals of Stockenstrom coloured people in the 1980s, the effects of displacement on them, and their involvement in current land claims issues. This dissertation seeks to redress these lacunae and provide information from "the underside" on the Kat River Rebellion of 1851-1853. In order to accomplish this, between 2011 and 2016 the author interviewed, with their consent, people of Khoikhoi descent in Kat River, recording, transcribing and analysing the interviews. The interviews, which range from conversations with male and female subsistence farmers and lay preachers to activists - such as the late Manie Loots, aka James Stewart - are set in the broader context of a selective Kat River history from 1829 to the present. Vagrancy legislation during the historical period is discussed; showing the link between pauperism, vagrancy, and colonial perceptions of disease such as leprosy, which was often associated with "loose" women. It is argued that the above perceptions, together with fear, led to the targeting of women and lepers during the attack on Fort Armstrong in 1852. Despite attempts to marginalise them, it was found that both colonial women, including rebels, and women in present-day Kat River exercised, and continue to exercise, remarkable agency. This thesis also reassesses the ideological bases of the Kat River Settlement, arguing that they were cultivation and militarism, with the latter exemplified in the Kat River settlers' service in frontier wars. Further, it found that neo-Marxist theories of commoning can shed light on the etiology of the Kat River Rebellion, and that people, whose access to their commons or other rights is restricted or denied, become radicalised. It was also found that, although their dispossession from Kat River took place in the 1980s, the interviewees, who all demonstrated strong ties to the land on which they grew up, still feel the effects of it, their all-consuming aim being the recognition of their land claims and the restoration of their titles
Galactic Gas Flows and their Role in the History and Evolution of the Magellanic System
No full textWithin our Galactic backyard, the Magellanic System, composed of the Large and Small Magellanic Clouds, is exchanging millions to billions of solar masses worth of material to the Milky Way. In two different studies, we explored this exchange and its impact on the Galactic environment. In the first study, a galactic outflow has erupted due to supernovae explosions within the disk. We present the first spectroscopically resolved H-alpha emission map of this wind. Kinematically, we find that the diffuse gas in the warm-ionized phase of the wind persists at both low (100km/s) velocities, relative to the LMC's HI disk. Furthermore, we find that the high-velocity component spatially aligns with the most intense star-forming region, 30~Doradus. We, therefore, conclude that this high-velocity material traces an active outflow. This wind is ejecting an estimated log(Mionized/Mo)=7.51 +/- 0.15 worth of material off the near-side of the galaxy. The second study observes tidally stripped gas that leads the LMC's orbit. This material formed into a massive complex called the Leading Arm that contains multiple sub-structures of gas. We investigate the physical and ionization conditions of this structure using Hubble Space Telescope/Cosmic Origins Spectrograph UV absorption-line and 21\,cm \hi\ emission-line observations along 13 sightlines. Additionally, we use Cloudy radiative transfer modeling to estimate their average temperatures, densities, ionization fractions, and thermal pressures. We find that most Leading Arm sub-structures exhibit multiple absorbers along their lines of sight, indicating a complex three-dimensional structure. Using the ionization fractions, we estimate that the total (neutral plus ionized) hydrogen mass of the LA sub-structures is M_H=3.0x10^8 Mo across a velocity range of +100 < vLSR < +240 km/s. In both studies, the material at play has the potential to fall onto the Milky Way and produce the future generation of solar systems
The Effects of Environment on Galaxy Evolution in Mapping Nearby Galaxies at Apache Point Observatory (MaNGA)
No full textGalaxy interactions and mergers are known to have been a fundamental process in the hierarchical formation of the Universe. These galaxy interactions first occurred between low-mass galaxies, analogous to today's dwarf galaxies. There have been a lack of studies on dwarf-dwarf galaxy interactions due to the difficulties in observing them. The development of better technology and telescopes has allowed the field to begin to gather the much-needed information on these events. This pilot study represents the first to examine the effects of dwarf-dwarf galaxy interactions on star-formation enhancement and star-formation rates using spatially and spectroscopically resolved data from the SDSS-IV MaNGA Survey. Two samples are studied to this effect: a sample of nine dwarf galaxies known to have close dwarf companions and a sample of fifteen dwarf galaxies known to be extremely isolated (~ 1 Mpc) from any other galaxies. The ionization conditions of each galaxy is studied using diagnostic diagrams which can classify regions within the galaxy as star-forming. The percentage of surface area which is star-forming and the central star-formation rate is calculated for each galaxy in both samples. We find that star formation is enhanced by almost a factor of four within the galaxies in the paired sample compared to those in the isolated sample. The methods developed for this study can be applied to much larger samples in the future once the data become available, thus allowing for further study of these crucial dwarf-dwarf galaxy interactions
Pressure from particle image velocimetry for convective flows: A Taylor\u92s hypothesis approach
No full textTaylors hypothesis is often applied in turbulent flow analysis to map temporal information into spatial information. Recent efforts in deriving pressure from particle image velocimetry (PIV) have proposed multiple approaches, each with its own weakness and strength. Application of Taylors hypothesis allows us to counter the weakness of an Eulerian approach that is described by de Kat & van Oudheusden (2012 Exp. Fluids 52 1089106). We build on the findings of de Kat & Ganapathisubramani (2013 Meas. Sci. Technol. 24 024002) and look in more detail into different ways of obtaining estimates for convection velocity on the determination of pressure from PIV using Taylor\u92s hypothesis. We also look at the influence of the omission of viscous terms. Results appear to indicate that pressure can indeed be obtained from PIV data in turbulent convective flows using the Taylors hypothesis approach, where there are no other methods to determine pressure. A more local estimate of convection velocity results in a pressure field that has less obvious defects. Other than a change in reference pressure for the pressure evaluation, inclusion or omission of the viscous terms appears to not have a significant effect
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