2,469 research outputs found
Hanging In, Stepping up and Stepping Out: Livelihood Aspirations and Strategies of the Poor Development in Practice
In recent years understanding of poverty and of ways in which people escape from or fall into poverty has become more holistic. This should improve the capabilities of policy analysts and others working to reduce poverty, but it also makes analysis more complex. This paper describes a simple schema which integrates multidimensional, multilevel and dynamic understandings of poverty, of poor people’s livelihoods, and of changing roles of agricultural systems. The paper suggests three broad types of strategy pursued by poor people: ‘hanging in’; ‘stepping up’; and ‘stepping out’. This simple schema explicitly recognises the dynamic aspirations of poor people; diversity among them; and livelihood diversification. It also brings together aspirations of poor people with wider sectoral, inter-sectoral and macro-economic questions about policies necessary for realisation of those aspirations
Evidence for deceleration in the radio jets of GRS1915+105?
There is currently a clear discrepancy in the proper motions measured on
different angular scales in the approaching radio jets of the black hole X-ray
binary GRS1915+105. Lower velocities were measured with the Very Large Array
(VLA) prior to 1996 than were subsequently found from higher-resolution
observations made with the Very Long Baseline Array and the Multi-Element Radio
Linked Interferometer Network. We initiated an observing campaign to use all
three arrays to attempt to track the motion of the jet knots from the 2006
February outburst of the source, giving us unprecedented simultaneous coverage
of all angular scales, from milliarcsecond scales out to arcsecond scales. The
derived proper motion, which was dominated by the VLA measurements, was found
to be 17.0 mas per day, demonstrating that there has been no significant
permanent change in the properties of the jets since 1994. We find no
conclusive evidence for deceleration of the jet knots, unless this occurs
within 70 mas of the core. We discuss possible causes for the varying proper
motions recorded in the literature.Comment: Accepted for publication in MNRAS. 13 pages, 10 figure
From solid solution to cluster formation of Fe and Cr in -Zr
To understand the mechanisms by which Fe and Cr additions increase the
corrosion rate of irradiated Zr alloys, a combination of experimental (atom
probe tomography, x-ray diffraction and thermoelectric power measurements) and
modelling (density functional theory) techniques are employed to investigate
the non-equilibrium solubility and clustering of Fe and Cr in binary Zr alloys.
Cr occupies both interstitial and substitutional sites in the {\alpha}-Zr
lattice, Fe favours interstitial sites, and a low-symmetry site that was not
previously modelled is found to be the most favourable for Fe. Lattice
expansion as a function of alloying concentration (in the dilute regime) is
strongly anisotropic for Fe additions, expanding the -axis while contracting
the -axis. Defect clusters are observed at higher solution concentrations,
which induce a smaller amount of lattice strain compared to the dilute defects.
In the presence of a Zr vacancy, all two-atom clusters are more soluble than
individual point defects and as many as four Fe or three Cr atoms could be
accommodated in a single Zr vacancy. The Zr vacancy is critical for the
increased solubility of defect clusters, the implications for irradiation
induced microstructure changes in Zr alloys are discussed.Comment: 15 pages including figure, 9 figures, 2 tables. Submitted for
publication in Acta Mater, Journal of Nuclear Materials (2015
A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
We present a solution for the ultraviolet (UV) - submillimeter (submm) interstellar radiation fields (ISRFs) of the Milky Way, derived from modelling COBE, IRAS and Planck maps of the all-sky emission in the near-, mid-, far-infrared and submm. The analysis uses the axisymmetric radiative transfer (RT) model that we have previously implemented to model the panchromatic spectral energy distributions (SEDs) of star forming galaxies in the nearby universe, but with a new methodology allowing for optimisation of the radial and vertical geometry of stellar emissivity and dust opacity, as deduced from the highly resolved emission seen from the vantage point of the Sun. As such, this is the first self-consistent model of the broad-band continuum emission from the Milky Way. In this paper, we present model predictions for the spatially integrated SED of the Milky Way as seen from the Sun, showing good agreement with the data, and give a detailed description of the solutions for the distribution of ISRFs, as well as their physical origin, throughout the volume of the galaxy. We explore how the spatial and spectral distribution of our new predictions for the ISRF in the Milky Way affects the amplitude and spectral distribution of the gamma-rays produced via Inverse Compton scattering for cosmic ray electrons situated at different positions in the galaxy, as well as the attenuation of the gamma-rays due to interactions of the gamma-ray photons with photons of the ISRF. We also compare and contrast our solutions for the ISRF with those incorporated in the GALPROP package used for modelling the high energy emission from cosmic rays in the Milky Way
Solid-phase C60 in the peculiar binary XX Oph?
We present infrared spectra of the binary XX Oph obtained with the Infrared Spectrograph on the Spitzer Space Telescope. The data show some evidence for the presence of solid C60– the first detection of C60 in the solid phase – together with the well-known ‘unidentified infrared’ emission features. We suggest that, in the case of XX Oph, the C60 is located close to the hot component, and that in general it is preferentially excited by stars having effective temperatures in the range 15 000–30 000 K. C60 may be common in circumstellar environments, but unnoticed in the absence of a suitable exciting source
Incoherent transient radio emission from stellar-mass compact objects in the SKA era
The universal link between the processes of accretion and ejection leads to
the formation of jets and outflows around accreting compact objects. Incoherent
synchrotron emission from these outflows can be observed from a wide range of
accreting binaries, including black holes, neutron stars, and white dwarfs.
Monitoring the evolution of the radio emission during their sporadic outbursts
provides important insights into the launching of jets, and, when coupled with
the behaviour of the source at shorter wavelengths, probes the underlying
connection with the accretion process. Radio observations can also probe the
impact of jets/outflows (including other explosive events such as magnetar
giant flares) on the ambient medium, quantifying their kinetic feedback.
The high sensitivity of the SKA will open up new parameter space, enabling
the monitoring of accreting stellar-mass compact objects from their bright,
Eddington-limited outburst states down to the lowest-luminosity quiescent
levels, whose intrinsic faintness has to date precluded detailed studies. A
census of quiescently accreting black holes will also constrain binary
evolution processes. By enabling us to extend our existing investigations of
black hole jets to the fainter jets from neutron star and white dwarf systems,
the SKA will permit comparative studies to determine the role of the compact
object in jet formation. The high sensitivity, wide field of view and
multi-beaming capability of the SKA will enable the detection and monitoring of
all bright flaring transients in the observable local Universe, including the
ULXs, ...
[Abridged]
This chapter reviews the science goals outlined above, demonstrating the
progress that will be made by the SKA. We also discuss the potential of the
astrometric and imaging observations that would be possible should a
significant VLBI component be included in the SKA.Comment: To be published in: "Advancing Astrophysics with the Square Kilometre
Array", Proceedings of Science, PoS(AASKA14
Economics of One Health: Costs and benefits of integrated West Nile virus surveillance in Emilia-Romagna
Since 2013 in Emilia-Romagna, Italy, surveillance information generated in the public health and in the animal health sectors has been shared and used to guide public health interventions to mitigate the risk of West Nile virus (WNV) transmission via blood transfusion. The objective of the current study was to identify and estimate the costs and benefits associated with this One Health surveillance approach, and to compare it to an approach that does not integrate animal health information in blood donations safety policy (uni-sectoral scenario). Costs of human, animal, and entomological surveillance, sharing of information, and triggered interventions were estimated. Benefits were quantified as the averted costs of potential human cases of WNV neuroinvasive disease associated to infected blood transfusion. In the 2009–2015 period, the One Health approach was estimated to represent a cost saving of €160,921 compared to the uni-sectoral scenario. Blood donation screening was the main cost for both scenarios. The One Health approach further allowed savings of €1.21 million in terms of avoided tests on blood units. Benefits of the One Health approach due to short-term costs of hospitalization and compensation for transfusion-associated disease potentially avoided, were estimated to range from €0 to €2.98 million according to the probability of developing WNV neuroinvasive disease after receiving an infected blood transfusion
First e-VLBI observations of GRS 1915+105
We present results from the first successful open call e-VLBI science run,
observing the X-ray binary GRS 1915+105. e-VLBI science allows the rapid
production of VLBI radio maps, within hours of an observation rather than
weeks, facilitating a decision for follow-up observations. A total of 6
telescopes observing at 5 GHz across the European VLBI Network (EVN) were
correlated in real time at the Joint Institute for VLBI in Europe (JIVE).
Constant data rates of 128 Mbps were transferred from each telescope, giving 4
TB of raw sampled data over the 12 hours of the whole experiment. Throughout
this, GRS 1915+105 was observed for a total of 5.5 hours, producing 2.8 GB of
visibilities of correlated data. A weak flare occurred during our observations,
and we detected a slightly resolved component of 2.7 x 1.2 milliarcsecond with
a position angle of 140 (+/-2) degrees. The peak brightness was 10.2 mJy per
beam, with a total integrated radio flux of 11.1 mJy.Comment: Accepted for publication in MNRAS 4 pages, 3 figure
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