6,094 research outputs found
Postfledging Survival, Movements, and Dispersal of Ring Ouzels (Turdus torquatus)
We thank Invercauld Estate for cooperation with access to Glen Clunie. S. Redpath, J. Wilson, and S. Roos provided valuable comments on the manuscript. This study was funded by the Royal Society for the Protection of Birds, Scottish Natural Heritage, and the Cairngorms National Park Authority. J.L.L. was supported by the Natural Environment Research Council.Peer reviewedPublisher PD
Measurement of Photon Statistics with Live Photoreceptor Cells
We analyzed the electrophysiological response of an isolated rod
photoreceptor of Xenopus laevis under stimulation by coherent and
pseudo-thermal light sources. Using the suction electrode technique for single
cell recordings and a fiber optics setup for light delivery allowed
measurements of the major statistical characteristics of the rod response. The
results indicate differences in average responses of rod cells to coherent and
pseudo-thermal light of the same intensity and also differences in
signal-to-noise ratios and second order intensity correlation functions. These
findings should be relevant for interdisciplinary studies seeking applications
of quantum optics in biology.Comment: 6 pages, 7 figure
Magnetic Quantum Dot: A Magnetic Transmission Barrier and Resonator
We study the ballistic edge-channel transport in quantum wires with a
magnetic quantum dot, which is formed by two different magnetic fields B^* and
B_0 inside and outside the dot, respectively. We find that the electron states
located near the dot and the scattering of edge channels by the dot strongly
depend on whether B^* is parallel or antiparallel to B_0. For parallel fields,
two-terminal conductance as a function of channel energy is quantized except
for resonances, while, for antiparallel fields, it is not quantized and all
channels can be completely reflected in some energy ranges. All these features
are attributed to the characteristic magnetic confinements caused by nonuniform
fields.Comment: 4 pages, 4 figures, to be published in Physical Review Letter
Stabilization of single-electron pumps by high magnetic fields
We study the effect of perpendicular magnetic fields on a single-electron
system with a strongly time-dependent electrostatic potential. Continuous
improvements to the current quantization in these electron pumps are revealed
by high-resolution measurements. Simulations show that the sensitivity of
tunnel rates to the barrier potential is enhanced, stabilizing particular
charge states. Nonadiabatic excitations are also suppressed due to a reduced
sensitivity of the Fock-Darwin states to electrostatic potential. The
combination of these effects leads to significantly more accurate current
quantization
Penal Agnosis and Historical Denial: Problematising ‘Common Sense’ Understandings of Prison Officers and Violence in Prison
The aim of this chapter is to consider if the much-publicised ‘causal relationship’ between prison officer numbers and prisoner violence is a form of ‘penal agnosis’: the cultural production of penal ignorance (Proctor, Agnotology: a missing term to describe the cultural production of ignorance. In R. Proctor & L. Schiebinger (Eds.), Agnotology: the making and unmaking of ignorance. Stanford: Stanford University Press, 2008). My use of penal agnosis draws directly from the writings of Cohen (States of denial. Cambridge: Polity, 2001) and Mathiesen (Silently silenced. Winchester: Waterside Press, 2004). Silencing techniques deployed in everyday life help to keep people quiet and neutralise criticism. Whilst these are varied, of particular concern here is when an event becomes “isolated in the present” (Mathiesen, Silently silenced. Winchester: Waterside Press, 2004: 42), specifically contemporary media and political discussions of prison officers and prison violence. This chapter provides a theoretical context to the invisibility of historical evidence regarding the deeply embedded harms and violence of penal confinement. It focuses on how the narrative of prison staffing levels is not only time-locked but also how the current understandings of the relationship with violence are derived primarily from the perspective of prison officers. Through critique of this approach an alternative space is opened for thinking differently about how to best respond to the current harms and violence of incarceration
An equatorial wind from the massive young stellar object S140 IRS 1
The discovery of the second equatorial ionized stellar wind from a massive
young stellar object is reported. High resolution radio continuum maps of S140
IRS 1 reveal a highly elongated source that is perpendicular to the larger
scale bipolar molecular outflow. This picture is confirmed by location of a
small scale monopolar near-IR reflection nebula at the base of the blueshifted
lobe. A second epoch of observations over a five year baseline show little
ordered outward proper motion of clumps as would have been expected for a jet.
A third epoch, taken only 50 days after the second, did show significant
changes in the radio morphology. These radio properties can all be understood
in the context of an equatorial wind driven by radiation pressure from the
central star and inner disc acting on the gas in the surface layers of the disc
as proposed by Drew et al. (1998). This equatorial wind system is briefly
compared with the one in S106IR, and contrasted with other massive young
stellar objects that drive ionized jets.Comment: 19 pages, 5 figures, accepted by ApJ, minor changes in light of
referees repor
Psychological health of Australian veterans of the 1991 Gulf War: an assessment using the SF-12, GHQ-12 and PCL-S
Background. Elevated rates of psychological morbidity and symptomatology have been widely reported in 1991 Gulf War veterans. The present study used brief self-report instruments to compare the psychological health of Australian Gulf War veterans with that of a randomly sampled military comparison group. Method. The 12-item Short Form Health Survey (SF-12), 12-item General Health Questionnaire (GHQ-12), Posttraumatic Stress Disorder Checklist – Specific (PCL-S) and Military Service Experience (MSE) questionnaire were administered to 1424 male Australian Gulf War veterans and 1548 male Australian Defence Force members who were operational at the time of the Gulf War conflict, but were not deployed there. Results. The Gulf War veterans exhibited poorer psychological health, as measured by the above three instruments, than the comparison group members. For Gulf War veterans, the number of stressful experiences, as measured by the MSE questionnaire, was correlated with scores on the three instruments. SF-12 mental health component summary scores and PCL-S caseness, but not GHQ-12 caseness, differed significantly between Gulf War veterans and comparison group members who had been on at least one active deployment. Conclusions. More than a decade after the 1991 Gulf War, Australian Gulf War veterans are exhibiting higher levels of current (past month) psychological ill-health, as measured using the GHQ-12 and PCL-S, as well as lower mental health status, as measured by the SF-12, than the comparison group. Although not a replacement for formal psychiatric diagnosis, instruments such as those above may aid in the assessment of veterans' psychological health.D. P. McKenzie, J. F. Ikin, A. C. McFarlane, M. Creamer, A. B. Forbes, H. L. Kelsall, D. C. Glass, P. Ittak and M. R. Si
Multi-dimensional modelling of X-ray spectra for AGN accretion-disk outflows III: application to a hydrodynamical simulation
We perform multi-dimensional radiative transfer simulations to compute
spectra for a hydrodynamical simulation of a line-driven accretion disk wind
from an active galactic nucleus. The synthetic spectra confirm expectations
from parameterized models that a disk wind can imprint a wide variety of
spectroscopic signatures including narrow absorption lines, broad emission
lines and a Compton hump. The formation of these features is complex with
contributions originating from many of the different structures present in the
hydrodynamical simulation. In particular, spectral features are shaped both by
gas in a successfully launched outflow and in complex flows where material is
lifted out of the disk plane but ultimately falls back. We also confirm that
the strong Fe Kalpha line can develop a weak, red-skewed line wing as a result
of Compton scattering in the outflow. In addition, we demonstrate that X-ray
radiation scattered and reprocessed in the flow has a pivotal part in both the
spectrum formation and determining the ionization conditions in the wind. We
find that scattered radiation is rather effective in ionizing gas which is
shielded from direct irradiation from the central source. This effect likely
makes the successful launching of a massive disk wind somewhat more challenging
and should be considered in future wind simulations.Comment: 14 pages, 8 figures. Accepted for publication by MNRA
Preschool literacy and reading performance in primary school
A literacia pré-escolar tem recebido uma crescente atenção. Neste estudo, participaram 70 crianças que iniciaram
o 1.º ano de escolaridade no ano letivo 2009/10 e que, na educação pré-escolar, frequentaram três instituições com abordagens
diferenciadas de leitura e de escrita. O estudo inclui quatro medidas repetidas no tempo nas áreas da fonologia, reconhecimento
de letras, palavras e velocidade de leitura. Os resultados sugerem que a abordagem específica à leitura na educação pré-escolar
condiciona o desempenho da leitura na instrução primária. Contudo, essa influência parece ser atenuada com o tempo. Por outro
lado, verificou-se que sujeitos que receberam instrução direta de leitura em idade pré-escolar (mas não treino fonológico) obtêm
resultados significativamente superiores em tarefas fonológicas aos de sujeitos que receberam treino fonológico prolongado
(mas não de leitura).The debate regarding kindergarten literacy has received increasing attention and social visibility. In this study, participants are 70 children who attended first grade in 2009/2010. Participants attended three kindergartens with unique approaches to reading. A four wave repeated measure design was conducted to investigate the growth of the children in phonological awareness, letter recognition, word recognition, and reading speed. Results suggest that the approach towards reading and writing in kindergarten affects children's performance in grades 1 and 2 of elementary school. This influence, however, seems to fade over time. Moreover, results show that children who received formal reading instruction in kindergarten, perform significantly better in phonological tasks than children who received direct and extended phonological instruction.(undefined)info:eu-repo/semantics/publishedVersio
Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties
The late-time spectra of Type Ia supernovae (SNe Ia) are powerful probes of
the underlying physics of their explosions. We investigate the late-time
optical and near-infrared spectra of seven SNe Ia obtained at the VLT with
XShooter at 200 d after explosion. At these epochs, the inner Fe-rich ejecta
can be studied. We use a line-fitting analysis to determine the relative line
fluxes, velocity shifts, and line widths of prominent features contributing to
the spectra ([Fe II], [Ni II], and [Co III]). By focussing on [Fe II] and [Ni
II] emission lines in the ~7000-7500 \AA\ region of the spectrum, we find that
the ratio of stable [Ni II] to mainly radioactively-produced [Fe II] for most
SNe Ia in the sample is consistent with Chandrasekhar-mass delayed-detonation
explosion models, as well as sub-Chandrasekhar mass explosions that have
metallicity values above solar. The mean measured Ni/Fe abundance of our sample
is consistent with the solar value. The more highly ionised [Co III] emission
lines are found to be more centrally located in the ejecta and have broader
lines than the [Fe II] and [Ni II] features. Our analysis also strengthens
previous results that SNe Ia with higher Si II velocities at maximum light
preferentially display blueshifted [Fe II] 7155 \AA\ lines at late times. Our
combined results lead us to speculate that the majority of normal SN Ia
explosions produce ejecta distributions that deviate significantly from
spherical symmetry.Comment: 17 pages, 12 figure, accepted for publication in MNRA
- …