56,632 research outputs found
zCOSMOS: A large VLT/VIMOS redshift survey covering 0 < z < 3 in the COSMOS field
zCOSMOS is a large-redshift survey that is being undertaken in the COSMOS field using 600 hr of observation
with the VIMOS spectrograph on the 8 m VLT. The survey is designed to characterize the environments of COSMOS
galaxies from the 100 kpc scales of galaxy groups up to the 100 Mpc scale of the cosmic web and to produce diagnostic
information on galaxies and active galactic nuclei. The zCOSMOS survey consists of two parts: (1) zCOSMOSbright,
a magnitude-limited I-band I_(AB) < 22.5 sample of about 20,000 galaxies with 0.1 < z < 1.2 covering the whole
1.7 deg^2 COSMOS ACS field, for which the survey parameters at z ~ 0.7 are designed to be directly comparable to
those of the 2dFGRS at z ~ 0.1; and (2) zCOSMOS-deep, a survey of approximately 10,000 galaxies selected through
color-selection criteria to have 1.4 < z < 3.0, within the central 1 deg^2. This paper describes the survey design and the
construction of the target catalogs and briefly outlines the observational program and the data pipeline. In the first
observing season, spectra of 1303 zCOSMOS-bright targets and 977 zCOSMOS-deep targets have been obtained.
These are briefly analyzed to demonstrate the characteristics that may be expected from zCOSMOS, and particularly
zCOSMOS-bright, when it is finally completed between 2008 and 2009. The power of combining spectroscopic and
photometric redshifts is demonstrated, especially in correctly identifying the emission line in single-line spectra and in
determining which of the less reliable spectroscopic redshifts are correct and which are incorrect. These techniques
bring the overall success rate in the zCOSMOS-bright so far to almost 90% and to above 97% in the 0.5 < z < 0.8
redshift range. Our zCOSMOS-deep spectra demonstrate the power of our selection techniques to isolate high-redshift
galaxies at 1.4 < z < 3.0 and of VIMOS to measure their redshifts using ultraviolet absorption lines
Recruiting and retaining children and families' social workers. The potential of work discussion groups
Current difficulties with the recruitment and retention of children and families' social workers have been formally acknowledged. However, although initiatives which focus on remuneration and career progression are clearly welcome, research and evidence from practice highlights how social workers themselves place high value on the availability of good quality supervision. Yet, questions remain about whether first-line managers have the time or are even in the best position to offer this support.
This article draws on the experience and evaluation of one particular model of supervision — 'work discussion groups' —and explores its impact with residential social work staff and teachers as well as the potential for further developments of this kind
Slip boundary conditions for shear flow of polymer melts past atomically flat surfaces
Molecular dynamics simulations are carried out to investigate the dynamic
behavior of the slip length in thin polymer films confined between atomically
smooth thermal surfaces. For weak wall-fluid interactions, the shear rate
dependence of the slip length acquires a distinct local minimum followed by a
rapid growth at higher shear rates. With increasing fluid density, the position
of the local minimum is shifted to lower shear rates. We found that the ratio
of the shear viscosity to the slip length, which defines the friction
coefficient at the liquid/solid interface, undergoes a transition from a nearly
constant value to the power law decay as a function of the slip velocity. In a
wide range of shear rates and fluid densities, the friction coefficient is
determined by the product of the value of surface induced peak in the structure
factor and the contact density of the first fluid layer near the solid wall.Comment: 27 pages, 11 figure
Haze in the Mars atmosphere as revealed by the Mariner 4 television data
Photometric investigation of haze in Mars atmosphere revealed by Mariner 4 television dat
THE ADOPTION AND DIFFUSION OF LEVEL FIELDS AND BASINS
Strategic investments in agriculture often are lumpy and irreversible, with significant impacts on operating and fixed costs. Leveling cotton fields to zero slope in central Arizona is a strategic decision made by relatively younger farmers who are farming fine-textured soils in irrigation districts with higher expected water costs. The diffusion of the technology across the region between 1968-89 appears to be both a function of institutional changes (e.g., the Groundwater Management Act of 1980, the Central Arizona Project) and the long-run expected price changes induced by these new policies.Crop Production/Industries,
Rate effects on layering of a confined linear alkane
We perform drainage experiments of a linear alkane fluid (n-hexadecane) down
to molecular thicknesses, and focus on the role played by the confinement rate.
We show that molecular layering is strongly influenced by the velocity at which
the confining walls are approached: under high enough shear rates, the confined
medium behaves as a structureless liquid of enhanced viscosity for film
thickness below 10 nm. Our results also lead us to conclude that a
rapidly confined film can be quenched in a metastable disordered state, which
might be related with recent intriguing results on the shear properties of
confined films produced at different rates [Zhu and Granick, Phys. Rev. Lett.
{\bf 93}, 096101 (2004)]
Making academia more accessible
Academia can be a challenging place to work and academics who have a disability, neurodiversity or chronic illness are further disadvantaged, as non-stereotypical ways of working are not necessarily supported or catered for. The remit of this paper is to provide practical ideas and recommendations to address accessibility issues in events and conferences as a first step to improving existing working conditions. We start with providing a brief overview of and background to the issues of ableism, disabilities, chronic illnesses and neurodiversities in academia. We then offer a detailed description of the organisational and developmental strategies relating to the Ableism in Academia conference to practically demonstrate how accessibility can be achieved. Despite vast literature available on theorisations of reasonable adjustments and some individual handbooks on conference accessibility, noted the absence of a systematic write-up of a case study that would demonstrate the thought processes required for the organisation of a fully accessible and inclusive event. This paper provides almost a step-by-step rationale and rundown of the decisions that had to be taken in order to facilitate an accessible event. After a brief consideration of challenges we encountered along the way, we share personal reflections regarding the event and future developments
Hyperon bulk viscosity in strong magnetic fields
We study the bulk viscosity of neutron star matter including
hyperons in the presence of quantizing magnetic fields. Relaxation time and
bulk viscosity due to both the non-leptonic weak process involving
hyperons and direct Urca processes are calculated here. In the presence of a
strong magnetic field of G, the hyperon bulk viscosity coefficient is
reduced whereas bulk viscosity coefficients due to direct Urca processes are
enhanced compared with their field free cases when many Landau levels are
populated by protons, electrons and muons.Comment: LaTex, 28 pages including 9 figures; new results are discussed in
section I
Electrodynamics of Magnetars IV: Self-Consistent Model of the Inner Accelerator, with Implications for Pulsed Radio Emission
We consider the voltage structure in the open-field circuit and outer
magnetosphere of a magnetar. The standard polar-cap model for radio pulsars is
modified significantly when the polar magnetic field exceeds 1.8x10^{14} G.
Pairs are created by accelerated particles via resonant scattering of thermal
X-rays, followed by the nearly instantaneous conversion of the scattered photon
to a pair. A surface gap is then efficiently screened by e+- creation, which
regulates the voltage in the inner part of the circuit to ~10^9 V. We also
examine the electrostatic gap structure that can form when the magnetic field
is somewhat weaker, and deduce a voltage 10-30 times larger over a range of
surface temperatures. We examine carefully how the flow of charge back to the
star above the gap depends on the magnitude of the current that is extracted
from the surface of the star, on the curvature of the magnetic field lines, and
on resonant drag. The rates of different channels of pair creation are
determined self-consistently, including the non-resonant scattering of X-rays,
and collisions between gamma rays and X-rays. We find that the electrostatic
gap solution has too small a voltage to sustain the observed pulsed radio
output of magnetars unless i) the magnetic axis is nearly aligned with the
rotation axis and the light of sight; or ii) the gap is present on the closed
as well as the open magnetic field lines. Several properties of the radio
magnetars -- their rapid variability, broad pulses, and unusually hard radio
spectra -- are consistent with a third possibility, that the current in the
outer magnetosphere is strongly variable, and a very high rate of pair creation
is sustained by a turbulent cascade.Comment: 32 pages, submitted to the Astrophysical Journa
Young stars and dust in AFGL437: NICMOS/HST polarimetric imaging of an outflow source
We present near infrared broad band and polarimetric images of the compact
star forming cluster AFGL437 obtained with the NICMOS instrument aboard HST.
Our high resolution images reveal a well collimated bipolar reflection
nebulosity in the cluster and allow us to identify WK34 as the illuminating
source. The scattered light in the bipolar nebulosity centered on this source
is very highly polarized (up to 79%). Such high levels of polarization implies
a distribution of dust grains lacking large grains, contrary to the usual dust
models of dark clouds. We discuss the geometry of the dust distribution giving
rise to the bipolar reflection nebulosity and make mass estimates for the
underlying scattering material. We find that the most likely inclination of the
bipolar nebulosity, south lobe inclined towards Earth, is consistent with the
inclination of the large scale CO molecular outflow associated with the
cluster, strengthening the identification of WK34 as the source powering it.Comment: 26 pages, 10 figues. Accepted for publication in the Astrophysical
Journa
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