6,321 research outputs found
Double window viewing chamber assembly
A viewing chamber which permits observation of a sample retained therein includes a pair of double window assemblies mounted in opposed openings in the walls thereof so that a light beam can directly enter and exit from the chamber. A flexible mounting arrangement for the outer windows of the window assemblies enables the windows to be brought into proper alignment. An electrical heating arrangement prevents fogging of the outer windows whereas desiccated air in the volume between the outer and inner windows prevents fogging of the latter
Corrigendum: Editorial: Visual Snow: Old Problem, New Understanding.
[This corrects the article DOI: 10.3389/fneur.2022.884752.]
X-ray and Radio Interactions in the Cores of Cooling Flow Clusters
We present high resolution ROSAT x-ray and radio observations of three
cooling flow clusters containing steep spectrum radio sources at their cores.
All three systems exhibit strong signs of interaction between the radio plasma
and the hot intracluster medium. Two clusters, A133 and A2626, show enhanced
x-ray emission spatially coincident with the radio source whereas the third
cluster, A2052, exhibits a large region of x-ray excess surrounding much of the
radio source. Using 3-D numerical simulations, we show that a perturbed jet
propagating through a cooling flow atmosphere can give rise to amorphous radio
morphologies, particularly in the case where the jet was ``turned off'' and
allowed to age passively. In addition, the simulated x-ray surface brightness
produced both excesses and deficits as seen observationally.Comment: 25 pages, 10 figures, accepted for publication in A
VLA 1.4 GHz Catalogs of the Abell 370 and Abell 2390 Cluster Fields
We present 1.4 GHz catalogs for the cluster fields Abell 370 and Abell 2390
observed with the Very Large Array. These are two of the deepest radio images
of cluster fields ever taken. The Abell 370 image covers an area of 40'x40'
with a synthesized beam of ~1.7" and a noise level of ~5.7 uJy near field
center. The Abell 2390 image covers an area of 34'x34' with a synthesized beam
of ~1.4" and a noise level of ~5.6 uJy near field center. We catalog 200
redshifts for the Abell 370 field. We construct differential number counts for
the central regions (radius < 16') of both clusters. We find that the faint
(S_1.4GHz < 3 mJy) counts of Abell 370 are roughly consistent with the highest
blank field number counts, while the faint number counts of Abell 2390 are
roughly consistent with the lowest blank field number counts. Our analyses
indicate that the number counts are primarily from field radio galaxies. We
suggest that the disagreement of our counts can be largely attributed to cosmic
variance.Comment: 13 pages, accepted for publication in ApJ
Open Space – a collaborative process for facilitating Tourism IT partnerships
The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: “how do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?” The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships
Aeolian transport layer
We investigate the airborne transport of particles on a granular surface by
the saltation mechanism through numerical simulation of particle motion coupled
with turbulent flow. We determine the saturated flux and show that its
behavior is consistent with a classical empirical relation obtained from wind
tunnel measurements. Our results also allow to propose a new relation valid for
small fluxes, namely, , where and
are the shear and threshold velocities of the wind, respectively, and
the scaling exponent is . We obtain an expression for the
velocity profile of the wind distorted by the particle motion and present a
dynamical scaling relation. We also find a novel expression for the dependence
of the height of the saltation layer as function of the wind velocity.Comment: 4 pages, 4 figure
Magnetic fields in cluster cores: Faraday rotation in A400 and A2634
We present Faraday rotation data for radio sources in the centers of the
Abell clusters A400 and A2634. These clusters contain large (> 100 kpc), tailed
radio sources, each attached to the central cD galaxy. These clusters do not
have strong cooling cores. Our data extend previous work on rotation measure in
cluster centers to larger scales and non-cooling clusters. The rotation
measure, and thus the magnetic field, is ordered on scales 10-20 kpc in both
clusters. The geometry of the rotation measure appears to be determined by the
distribution of the X-ray emitting gas, rather than by the radio tails
themselves. We combine our data with previously published X-ray and radio data
in order to analyze the magnetic fields in all 12 clusters whose central radio
sources have been imaged in rotation measure. We find that the fields are
dynamically significant in most clusters. We argue that the Faraday data
measure fields in the intracluster medium, rather than in a skin of the radio
source. Finally, we consider the nature and maintenance of the magnetic fields
in these clusters, and conclude that either the cluster-wide field exists at
similar levels, or that a weaker cluster-wide field is amplified by effects in
the core.Comment: Accepted for ApJ. 43 pages including 10 embedded figures. Higher
resolution versions of the figures available at
http://www.aoc.nrao.edu/~jeilek/pubs/Eilekpub.htm
Movement characteristics of international and elite domestic netball players during match-play
This study quantified and compared the movement characteristics of elite domestic and international netball match-play, including fifteen individual players who compete at both levels. Microtechnology data were collected across 75 matches in a league-wide study from players (n = 113) competing in the Netball Superleague (elite domestic) and from international players (n = 23) in 22 international matches. Players were categorised according to the seven playing positions. Accelerometer-derived variables were analysed per whole-match and per quarter, for both absolute (i.e., volume) and relative to duration (i.e., intensity [per minute]) values. The median playing duration ranged across positions from 23.6 to 42.4 minutes at international and 31.6 to 48.1 minutes at domestic level. International matches were greater than elite domestic competition for relative variables across all positions. Moderate to large effect sizes (1.00–1.50) were found between playing levels for PlayerLoadTM per minute (AU·min-1). Significant decreases in both absolute and relative variables were observed across quarters for both competition levels. The movement characteristics are position dependent, with greater absolute characteristics at domestic level across whole-match analysis, but greater relative characteristics at international level. These findings provide practitioners with information to guide training prescription, return-to-play protocols, and transitioning athletes between levels of competition
Gravitational waves from rapidly rotating neutron stars
Rapidly rotating neutron stars in Low Mass X-ray Binaries have been proposed
as an interesting source of gravitational waves. In this chapter we present
estimates of the gravitational wave emission for various scenarios, given the
(electromagnetically) observed characteristics of these systems. First of all
we focus on the r-mode instability and show that a 'minimal' neutron star model
(which does not incorporate exotica in the core, dynamically important magnetic
fields or superfluid degrees of freedom), is not consistent with observations.
We then present estimates of both thermally induced and magnetically sustained
mountains in the crust. In general magnetic mountains are likely to be
detectable only if the buried magnetic field of the star is of the order of
G. In the thermal mountain case we find that gravitational
wave emission from persistent systems may be detected by ground based
interferometers. Finally we re-asses the idea that gravitational wave emission
may be balancing the accretion torque in these systems, and show that in most
cases the disc/magnetosphere interaction can account for the observed spin
periods.Comment: To appear in 'Gravitational Waves Astrophysics: 3rd Session of the
Sant Cugat Forum on Astrophysics, 2014', Editor: Carlos F. Sopuert
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