7,005 research outputs found
Migration and Cultural Change: A Role for Gender and Social Networks?
From the Introduction:
To incorporate the insights from the literature on gender and migration, we focus upon three key concepts that have emerged regarding the role of social networks, households, and communities for affecting migration processes. The three key concepts we interrogate are: âsocial embeddednessâ (Portes and Sensenbrenner 1993), âcircular and cumulative causationâ (Massey 1990), and ârelative deprivationâ (Stark 1991). We propose considering these three concepts through the lens of a third area of research, the sociology of culture, and we draw upon ideas about identity formation, trust, and normative expectations. Our empirical examples come primarily from Thailand where we draw upon both secondary and primary data but also from secondary data from Latin America and the Caribbean migrant experiences. In our effort to demonstrate that social networks and gender are essential elements for understanding migration and cultural change, our discussion refers to international, internal, permanent, and temporary migration
Directives and Academics: educational developers, technology and the right support
There can be âan army of people involved in the development of academics as teachersâ
(Ling & CADAC, 2009) and the role of Educational Developers with technological
expertise is vital to the uptake and creative use of educational technologies in learning
contexts (Oliver, 2005). Even so, technology plays only a part in the teaching and learning
experience and must be underpinned with pedagogical wherewithal. At Victoria University
(VU) in Melbourne, a new VU Agenda expects the university to be known for educational
programmes âthat maximise opportunities for blended and eLearningâ.
This discussion examines the support available to staff using technologies for teaching. The
discussion covers two examples from different faculties where teaching staff have needed
to comply with Faculty or School directives to use particular university-supported
technologies (Lectopia and GradeMark). The comments about staff uptake of technologies
draw on general themes from evaluations administered in each faculty to gauge the
effectiveness of the technologies for teaching and to identify further professional
development needs. Unsurprisingly, the findings show that, without intensive and timely
support tailored to the specific requirements of academics, without academics having both
an understanding of the reason for the mandating of a technology as well as an ability to
influence that uptake, academics are likely to find ways to resist authoritarian directives.
The danger of encouraging academicsâ uptake of educational technologies without broader
educational development support to encourage good teaching practices that integrate
technology and good curriculum design became clear from the dat
Mars: Mariner 9 spectroscopic evidence for H2O ice clouds
Spectral features observed with the Mariner 9 Interferometer Spectrometer are identified as those of water ice. Measured spectra are compared with theoretical calulations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate water ice clouds composed of particles with mean radius 2.0 microns and integrated cloud mass 0.00005 g/sq cm
Information content of ozone retrieval algorithms
The algorithms are characterized that were used for production processing by the major suppliers of ozone data to show quantitatively: how the retrieved profile is related to the actual profile (This characterizes the altitude range and vertical resolution of the data); the nature of systematic errors in the retrieved profiles, including their vertical structure and relation to uncertain instrumental parameters; how trends in the real ozone are reflected in trends in the retrieved ozone profile; and how trends in other quantities (both instrumental and atmospheric) might appear as trends in the ozone profile. No serious deficiencies were found in the algorithms used in generating the major available ozone data sets. As the measurements are all indirect in someway, and the retrieved profiles have different characteristics, data from different instruments are not directly comparable
Further Observational Evidence for a Critical Ionising Luminosity in Active Galaxies
We report the results of a survey for HI 21-cm absorption at redshifts of z >
2.6 in a new sample of radio sources with the Green Bank and Giant Metrewave
Radio Telescopes. From a total of 25 targets, we report zero detections in the
16 for which optical depth limits could be obtained. Based upon the detection
rate for z > 0.1 associated absorption, we would expect approximately four
detections. Of the 11 which have previously not been searched, there is
sufficient source-frame optical/ultra-violet photometry to determine the
ionising photon rate for four. Adding these to the literature, the hypothesis
that there is a critical rate of logQ = 56 ionising photons per second is now
significant at ~7 sigma. This reaffirms our assertion that searching z > 3
active galaxies for which optical redshifts are available selects sources in
which the ultra-violet luminosity is sufficient to ionise all of the neutral
gas in the host galaxy.Comment: Accepted by MNRA
A survey for redshifted molecular and atomic absorption lines - II. Associated HI, OH and millimetre lines in the z >~ 3 Parkes quarter-Jansky flat-spectrum sample
We present the results of a z>2.9 survey for HI 21-cm and molecular
absorption in the hosts of radio quasars using the GMRT and the Tidbinbilla
70-m telescope. Previously published searches, which are overwhelmingly at
redshifts of z<1, exhibit a 42% detection rate (31 out of 73 sources), and the
inclusion of our survey yields a 17% detection rate (2 out of 12 sources) at
z>2.5. We therefore believe that our high redshift selection is responsible for
our exclusive non-detections, and find that at ultra-violet luminosities of
>10e23 W/Hz, 21-cm absorption has never been detected. We also find this to not
only apply to our targets, but also those at low redshift exhibiting similar
luminosities, giving zero detections out of a total of 16 sources over z=0.24
to 3.8. This is in contrast to the < 10e23 W/Hz sources where there is a near
50% detection rate of 21-cm absorption.
The mix of 21-cm detections and non-detections is currently attributed to
orientation effects, where according to unified schemes of active galactic
nuclei, 21-cm absorption is more likely to occur in sources designated as radio
galaxies (type-2 objects, where the nucleus is viewed through dense obscuring
circumnuclear gas) than in quasars(type-1 objects, where we have a direct view
to the nucleus). However, due to the exclusively high ultra-violet luminosities
of our targets it is not clear whether orientation effects alone can wholly
account for the distribution, although there exists the possibility that the
large luminosities are indicative of a changing demographic of galaxy types. We
also find that below luminosities of ~10e23 W/Hz, both type-1 and type-2
objects have a 50% likelihood of exhibiting 21-cm absorption.Comment: 21 pages, accepted by MNRA
Nurses\u27 Alumnae Association Bulletin, May 1963
President\u27s Letter
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Mediocrity
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Marriages, New Arrivals and Necrology
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Independent Expert Scientific Panel â Report on Unconventional Oil and Gas
No abstract available
The hidden X-ray breaks in afterglow light curves
Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a
perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift
era. Specifically, relatively few breaks, consistent with jet breaks, are
observed in the X-ray light curves of these bursts. If these breaks are truly
missing, it has serious consequences for the interpretation of GRB jet
collimation and energy requirements, and the use of GRBs as standard candles.
Here we address the issue of X-ray breaks which are possibly 'hidden' and
hence the light curves are misinterpreted as being single power-laws. We show
how a number of precedents, including GRB 990510 & GRB 060206, exist for such
hidden breaks and how, even with the well sampled light curves of the Swift
era, these breaks may be left misidentified. We do so by synthesising X-ray
light curves and finding general trends via Monte Carlo analysis. Furthermore,
in light of these simulations, we discuss how to best identify achromatic
breaks in afterglow light curves via multi-wavelength analysis.Comment: 4 pages, contributed talk, submitted to the proceedings of Gamma Ray
Bursts 2007, Santa Fe, New Mexico, November 5-9 200
The Probability Distribution of Binary Pulsar Coalescence Rate Estimates. II. Neutron Star-White Dwarf Binaries
We consider the statistics of pulsar binaries with white dwarf companions
(NS-WD). Using the statistical analysis method developed by Kim et al. (2003)
we calculate the Galactic coalescence rate of NS-WD binaries due to
gravitational-wave emission. We find that the most likely values for the total
Galactic coalescence rate (R_tot) of NS-WD binaries lie in the range 0.2--10
per Myr depending on different assumed pulsar population models. For our
reference model, we obtain R_tot=4.11_(-2.56)^(+5.25) per Myr at a 68%
statistical confidence level. These rate estimates are not corrected for pulsar
beaming and as such they are found to be about a factor of 20 smaller than the
Galactic coalescence rate estimates for double neutron star systems. Based on
our rate estimates, we calculate the gravitational-wave background due to
coalescing NS-WD binaries out to extragalactic distances within the frequency
band of the Laser Interferometer Space Antenna. We find the contribution from
NS-WD binaries to the gravitational-wave background to be negligible.Comment: 20 pages, 2 figures, 2 tables, Accepted for publication in Ap
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