5,151 research outputs found
The influence of ship motion of manual control skills
The effects of ship motion on a range of typical manual control skills were examined on the Warren Spring ship motion simulator driven in heave, pitch, and roll by signals taken from the frigate HMS Avenger at 13 m/s (25 knots) into a force 4 wind. The motion produced a vertical r.m.s. acceleration of 0.024g, mostly between 0.1 and 0.3 Hz, with comparatively little pitch or roll. A task involving unsupported arm movements was seriously affected by the motion; a pursuit tracking task showed a reliable decrement although it was still performed reasonably well (pressure and free moving tracking controls were affected equally by the motion); a digit keying task requiring ballistic hand movements was unaffected. There was no evidence that these effects were caused by sea sickness. The differing response to motion of the different tasks, from virtual destruction to no effect, suggests that a major benefit could come from an attempt to design the man/control interface onboard ship around motion resistant tasks
Negotiating sexuality and masculinity in school sport: An autoethnography
This autoethnography explores challenging and ethically sensitive issues around sexual orientation, sexual identity and masculinity in the context of school sport. Through storytelling, I aim to show how sometimes ambiguous encounters with heterosexism, homophobia and hegemonic masculinity through sport problematise identity development for young same-sex attracted males. By foregrounding personal embodied experience, I respond to an absence of stories of gay and bisexual experiences among males in physical education and school sport, in an effort to reduce a continuing sense of Otherness and difference regarding same-sex attracted males. I rely on the story itself to express the embodied forms of knowing that inhabit the experiences I describe, and resist a finalising interpretation of the story. Instead, I offer personal reflections on particular theoretical and methodological issues which relate to both the form and content of the story
The host galaxies of three radio-loud quasars: 3C 48, 3C 345, and B2 1425+267
Observations with the Wide-Field/Planetary Camera-2 of the Hubble Space
Telescope (HST) are presented for three radio-loud quasars: 3C 48 (z=0.367), B2
1425+267 (z=0.366), and 3C 345 (z=0.594). All three quasars have luminous (~4
L^*) galaxies as hosts, which are either elliptical (B2 1425+267 and 3C 345) or
interacting (3C 48), and all hosts are 0.5 - 1.0 mag bluer in (V-I) than other
galaxies with the same overall morphology at similar redshifts to the quasars.
The host of 3C 48 has many H II regions and a very extended tidal tail.
All nine of the radio-loud quasars studied here and in Bahcall et al. (1997)
either have bright elliptical hosts or occur in interacting systems. There is a
robust correlation between the radio emission of the quasar and the luminosity
of host galaxy; the radio-loud quasars reside in galaxies that are on average
about 1 mag brighter than hosts of the radio-quiet quasars.Comment: Accepted for publication in ApJ. 3 postscript and 3 jpeg figures.
Original figures may be found in ftp://eku.sns.ias.edu/pub/sofia/RadioLoud
An optical parsec-scale jet from a massive young star in the Large Magellanic Cloud
Highly collimated parsec-scale jets, generally linked to the presence of an
accretion disk, are a commonly observed phenomenon from revealed low-mass young
stellar objects. In the past two decades, only a very few of these objects have
been directly (or indirectly) observed towards high-mass (M > 8 M)
young stellar objects, adding to the growing evidence that disk-mediated
accretion is a phenomenon also occurring in high-mass stars, the formation
mechanism of which is still poorly understood. Of the observed jets from
massive young stars, none is in the optical regime (due to these being
typically highly obscured by their native material), and none are found outside
of the Milky Way. Here, we report the detection of HH 1177, the first
extragalactic optical ionized jet originating from a massive young stellar
object located in the Large Magellanic Cloud. The jet is highly collimated over
the entire measured extent of at least 10 pc, and has a bipolar geometry. The
presence of a jet indicates ongoing, disk-mediated accretion, and together with
the high degree of collimation, this system is therefore likely to be an
up-scaled version of low-mass star formation. We conclude that the physics
governing jet launching and collimation is independent of stellar mass.Comment: 9 pages, 5 figures, 2 table
AEGIS: Infrared Spectroscopy of An Infrared Luminous Lyman Break Galaxy at z=3.01
We report the detection of rest--frame 6.2 and 7.7 \micron emission features
arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum
of an infrared-luminous Lyman break galaxy at z=3.01. This is currently the
highest redshift galaxy where these PAH emission features have been detected.
The total infrared luminosity inferred from the MIPS 24 \micron and radio flux
density is 2 L, which qualifies this object as a
so--called hyperluminous infrared galaxy (HyLIRG). However, unlike local
HyLIRGs which are generally associated with QSO/AGNs and have weak or absent
PAH emission features, this HyLIRG has very strong 6.2 and 7.7 \micron PAH
emission. We argue that intense star formation dominates the infrared emission
of this source, although we cannot rule out the presence of a deeply obscured
AGN. This LBG appears to be a distorted system in the HST ACS F606W and F814W
images, possibly indicating that a significant merger or interaction is driving
the large IR luminosity
The Quasar Pair Q 1634+267 A, B and the Binary QSO vs. Dark Lens Hypotheses
Deep HST/NICMOS H (F160W) band observations of the z=1.96 quasar pair Q
1634+267A,B reveal no signs of a lens galaxy to a 1 sigma threshold of
approximately 22.5 mag. The minimum luminosity for a normal lens galaxy would
be a 6L_* galaxy at z > 0.5, which is 650 times greater than our detection
threshold. Our observation constrains the infrared mass-to-light ratio of any
putative, early-type, lens galaxy to (M/L)_H > 690h_65 (1200h_65) for
Omega_0=0.1 (1.0) and H_0=65h_65 km/s/Mpc. We would expect to detect a galaxy
somewhere in the field because of the very strong Mg II absorption lines at
z=1.1262 in the Q 1634+267 A spectrum, but the HST H-band, I-band (F785LP) and
V-band (F555W) images require that any associated galaxy be very under-luminous
less than 0.1 L^*_H (1.0 L^*_I) if it lies within less than 40 h^{-1} (100
h^{-1}) kpc from Q 1634+267 A,B.
While the large image separation (3.86 arcsec) and the lack of a lens galaxy
strongly favor interpreting Q 1634+267A,B as a binary quasar system, the
spectral similarity remains a puzzle. We estimate that at most 0.06% of
randomly selected quasar pairs would have spectra as similar to each other as
the spectra of Q 1634+267 A and B. Moreover, spectral similarities observed for
the 14 quasar pairs are significantly greater than would be expected for an
equivalent sample of randomly selected field quasars. Depending on how strictly
we define similarity, we estimate that only 0.01--3% of randomly drawn samples
of 14 quasar pairs would have as many similar pairs as the observational
sample.Comment: 24 pages, including 4 figures, LaTex, ApJ accepted, comments from the
editor included, minor editorial change
Magma-Carbonate Interaction Processes and Associated CO2 Release at MerapiVolcano, Indonesia: Insights from Experimental Petrology
There is considerable evidence for continuing, late-stage interaction
between the magmatic system at Merapi volcano, Indonesia, and
local crustal carbonate (limestone). Calc-silicate xenoliths within
Merapi basaltic-andesite eruptive rocks display textures indicative
of intense interaction between magma and crustal carbonate, and
Merapi feldspar phenocrysts frequently contain crustally contaminated
cores and zones. To resolve the interaction processes between
magma and limestone in detail we have performed a series of
time-variable decarbonation experiments in silicate melt, at magmatic
pressure and temperature, using a Merapi basaltic-andesite
and local Javanese limestone as starting materials.We have used in
situ analytical methods to determine the elemental and strontium isotope
composition of the experimental products and to trace the textural,
chemical, and isotopic evolution of carbonate assimilation.
The major processes of magma^carbonate interaction identified
are: (1) rapid decomposition and degassing of carbonate; (2) generation
of a Ca-enriched, highly radiogenic strontium contaminant
melt, distinct from the starting material composition; (3) intense
CO2 vesiculation, particularly within the contaminated zones; (4)
physical mingling between the contaminated and unaffected melt
domains; (5) chemical mixing between melts. The experiments
reproduce many of the features of magma^carbonate interaction
observed in the natural Merapi xenoliths and feldspar phenocrysts.
The Ca-rich, high 87Sr/86Sr contaminant melt produced in the
experiments is considered as a precursor to the Ca-rich (often
âhyper-calcicâ) phases found in the xenoliths and the contaminated
zones inMerapi feldspars.The xenoliths also exhibit micro-vesicular
textures that can be linked to the CO2 liberation process seen in the
experiments.This study, therefore, provides well-constrained petrological
insights into the problem of crustal interaction at Merapi and
points toward the substantial impact of such interaction on the
volatile budget of the volcano
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