6,241 research outputs found
Mortality associated with avian reovirus infection in a free-living magpie (Pica pica) in Great Britain
Avian reoviruses (ARVs) cause a range of disease presentations in domestic, captive and free-living bird species. ARVs have been reported as a cause of significant disease and mortality in free-living corvid species in North America and continental Europe. Until this report, there have been no confirmed cases of ARV-associated disease in British wild birds
Mediatization of Emotion on Social Media: Forms and Norms in Digital Mourning Practices
This article provides the theoretical background for this Special Issue which explores the mediatization of emotion on social media as attested in different digital mourning practices. The overview discusses the affective and emotional turn alongside the mediatic turn in relation to key trends and foci in the study of affect/emotion. Our discussion points to a shift in conceptualizations of affect/emotion from mediated to mediatized practice, embedded in other social practices and subject to media and social media logics, affordances, and frames, which are worthy of empirical investigation. The article also presents key insights offered in the four articles of this Special Issue and foregrounds current and future directions in the study of mediatization, emotional sharing, and digital mourning practices
Isolating Triggered Star Formation
Galaxy pairs provide a potentially powerful means of studying triggered star
formation from galaxy interactions. We use a large cosmological N-body
simulation coupled with a well-tested semi-analytic substructure model to
demonstrate that the majority of galaxies in close pairs reside within cluster
or group-size halos and therefore represent a biased population, poorly suited
for direct comparison to ``field'' galaxies. Thus, the frequent observation
that some types of galaxies in pairs have redder colors than ``field'' galaxies
is primarily a selection effect. We select galaxy pairs that are isolated in
their dark matter halos with respect to other massive subhalos (N=2 halos) and
a control sample of isolated galaxies (N=1 halos) for comparison. We then apply
these selection criteria to a volume-limited subset of the 2dF Galaxy Redshift
Survey with M_Bj <= -19 and obtain the first clean measure of the typical
fraction of galaxies affected by triggered star formation and the average
elevation in the star formation rate. We find that 24% (30.5%) of these L^\star
and sub-L^{\star} galaxies in isolated 50 (30) kpc/h pairs exhibit star
formation that is boosted by a factor of >~ 5 above their average past value,
while only 10% of isolated galaxies in the control sample show this level of
enhancement. Thus, 14% (20 %) of the galaxies in these close pairs show clear
triggered star formation. The isolation criteria we develop provide a means to
constrain star formation and feedback prescriptions in hydrodynamic simulations
and a very general method of understanding the importance of triggered star
formation in a cosmological context. (Abridged.)Comment: 12 pages, 10 figures, emulateapj format, accepted by Ap
P04.85. Addressing nature deficit disorder: a quantitative survey study of multidimensional aspects of well-being among young adults at a wilderness camp
P05.17. Addressing nature deficit disorder: a mixed methods study of social well-being among young adults attending a wilderness science camp
Voltage-controlled electron tunnelling from a single self-assembled quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic cell
We perform high-resolution photocurrent (PC) spectroscopy to investigate
resonantly the neutral exciton ground-state (X0) in a single InAs/GaAs
self-assembled quantum dot (QD) embedded in the intrinsic region of an
n-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which
was formed from a Si delta-doped GaAs layer. Using such a device, a single-QD
PC spectrum of X0 is measured by sweeping the bias-dependent X0 transition
energy through that of a fixed narrow-bandwidth laser via the quantum-confined
Stark effect (QCSE). By repeating such a measurement for a series of laser
energies, a precise relationship between the X0 transition energy and bias
voltage is then obtained. Taking into account power broadening of the X0
absorption peak, this allows for high-resolution measurements of the X0
homogeneous linewidth and, hence, the electron tunnelling rate. The electron
tunnelling rate is measured as a function of the vertical electric field and
described accurately by a theoretical model, yielding information about the
electron confinement energy and QD height. We demonstrate that our devices can
operate as 2DEG-based QD photovoltaic cells and conclude by proposing two
optical spintronic devices that are now feasible.Comment: 34 pages, 11 figure
Projected free energies for polydisperse phase equilibria
A `polydisperse' system has an infinite number of conserved densities. We
give a rational procedure for projecting its infinite-dimensional free energy
surface onto a subspace comprising a finite number of linear combinations of
densities (`moments'), in which the phase behavior is then found as usual. If
the excess free energy of the system depends only on the moments used, exact
cloud, shadow and spinodal curves result; two- and multi-phase regions are
approximate, but refinable indefinitely by adding extra moments. The approach
is computationally robust and gives new geometrical insights into the
thermodynamics of polydispersity.Comment: 4 pages, REVTeX, uses multicol.sty and epsf.sty, 1 postscript figure
include
Low voltage control of ferromagnetism in a semiconductor p-n junction
The concept of low-voltage depletion and accumulation of electron charge in
semiconductors, utilized in field-effect transistors (FETs), is one of the
cornerstones of current information processing technologies. Spintronics which
is based on manipulating the collective state of electron spins in a
ferromagnet provides complementary technologies for reading magnetic bits or
for the solid-state memories. The integration of these two distinct areas of
microelectronics in one physical element, with a potentially major impact on
the power consumption and scalability of future devices, requires to find
efficient means for controlling magnetization electrically. Current induced
magnetization switching phenomena represent a promising step towards this goal,
however, they relay on relatively large current densities. The direct approach
of controlling the magnetization by low-voltage charge depletion effects is
seemingly unfeasible as the two worlds of semiconductors and metal ferromagnets
are separated by many orders of magnitude in their typical carrier
concentrations. Here we demonstrate that this concept is viable by reporting
persistent magnetization switchings induced by short electrical pulses of a few
volts in an all-semiconductor, ferromagnetic p-n junction.Comment: 11 pages, 4 figure
Manipulating O3/P2 phase ratio in bi-phasic sodium layered oxides via ionic radius control
Funding: This work was supported by the Faraday Institution (Grant number FIRG018). The authors would like to thank Dr. David Rochester at Lancaster University for conducting the ICP-OES experiments. A.B.N. would like to acknowledge funding by the Engineering and Physical Sciences Research Council under grant numbers EP/L017008/1, EP/R023751/1, and EP/T019298/1 for the electron microscopy analysis.Bi-phasic O3/P2 sodium layered oxides have emerged as leading candidates for the commercialisation of next-generation sodium-ion batteries. However, beyond simply altering the sodium content, rational control of the O3/P2 ratio in these materials has proven particularly challenging despite being crucial for the realization of high-performance electrode materials. Here, using abundant elements, we manipulate the O3/P2 ratio using the average ionic radius of the transition metal layer and different synthesis conditions. These methods allow deterministic control over the O3/P2 ratio, even for constant Na contents. In addition, tuning the O3/P2 ratio yields high-performing materials with different performance characteristics, with a P2-rich material achieving high rate capabilities and excellent cycling stability (92% retention, 50 cycles), while an O3-rich material displayed an energy density up to 430 Wh kg−1, (85%, 50 cycles). These insights will help guide the rational design of future high-performance materials for sodium-ion batteries.Publisher PDFPeer reviewe
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