2,019 research outputs found
Toward Effective Violence Mitigation: Transforming Political Settlements
Recognising the centrality of violence in the development process (though not subscribing to the notion that conflict and violence are development in reverse), in 2012–14 a group of researchers at the Institute of Development Studies (IDS) engaged in depth with the complex and thorny questions of how ‘new’ forms of violence in the developing world – as opposed to ‘traditional’ civil or intra-state war – should be understood; and through which policies they could best be prevented and/or mitigated. The result of this endeavour is a series of evidence-based reports that were produced in collaboration with Southern partners in a sample of four violence-affected countries in Africa: Nigeria (Niger Delta), Sierra Leone, Egypt and Kenya (Marsabit County).
The evidence from the four case studies suggests that – contrary to the early post-Cold War accounts of ‘barbarism’ and ‘senseless bloodshed’ – the violence we observe in many countries and locales today is about something. Yet, the analyses also show that the triggers, manifestations and effects of this violence – characterised as diffuse, recursive and globalised – cannot be captured by using the analytical tools developed to explain armed conflict within states. Strictly speaking, it would be misguided to label the violence in the Niger Delta, Marsabit County, Egypt and Sierra Leone as ‘civil war’, ‘internal armed conflict’ or ‘new war’. Instead, it is more accurate to speak of highly heterogeneous situations of violence or ‘fields of social violence’. At the same time, it is crucial not to dissociate these situations of violence from political processes by, for instance, reducing them to manifestations of criminality, such as homicide and illicit drug trafficking, or reflections of social problems like rampant youth unemployment, the use of prohibited psychoactive substances, and gang culture.UK Department for International Developmen
Beyond the Ferguson Effect on crime: Examining its influence on law enforcement personnel
The purpose of the current study is to examine the influence tensions over high-profile officer-involved shootings have had on Atlanta police officers’ ability to do their jobs and whether these impacts vary by officer race. Data was collected between August and October of 2016. A total of 241 police officers across six zones completed the self-administered survey. Findings indicate that while white officers, on average, felt the impacts of recent tensions surrounding officer-involved shootings more strongly, non-white officers were more likely to say they would leave policing if offered a better paying job in another field. This study provides insight into racial differences in the impacts of recent tensions and protests over fatal officer-involved shootings
Properties of galactic B[e] supergiants. IV. Hen3-298 and Hen3-303
We present the results of optical and near-IR spectroscopic and near-IR
photometric observations of the emission-line stars Hen3-298 and Hen3-303.
Strong emission in the H-alpha line is found in both objects. The presence of
Fe II and [O I] emission lines in the spectrum of Hen3-298 indicates that it is
a B[e] star. The double-peaked CO line profiles, found in the infrared spectrum
of Hen3-298, along with the optical line profiles suggest that the star is
surrounded by a rotating circumstellar disk. Both objects also show infrared
excesses, similar to those of B[e] stars. The radial velocities of the
absorption and emission lines as well as a high reddening level suggest that
the objects are located in the Norma spiral arm at a distance of 3-4.5 kpc. We
estimated a luminosity of log (L/L_sun) ~ 5.1 and a spectral type of no earlier
than B3 for Hen3-298. Hen3-303 seems to be a less luminous B-type object (log
(L/L_sun) ~ 4.3), located in the same spiral arm.Comment: 8 pages, 5 figures, accepted by Astronomy and Astrophysic
Gas damping force noise on a macroscopic test body in an infinite gas reservoir
We present a simple analysis of the force noise associated with the
mechanical damping of the motion of a test body surrounded by a large volume of
rarefied gas. The calculation is performed considering the momentum imparted by
inelastic collisions against the sides of a cubic test mass, and for other
geometries for which the force noise could be an experimental limitation. In
addition to arriving at an accurated estimate, by two alternative methods, we
discuss the limits of the applicability of this analysis to realistic
experimental configurations in which a test body is surrounded by residual gas
inside an enclosure that is only slightly larger than the test body itself.Comment: 8 pages. updated with correct translational damping coefficient for
cylinder on axis. added cylinder orthogonal to symmetry axis, force and
torque. slightly edited throughou
Identifying Young Brown Dwarfs Using Gravity-Sensitive Spectral Features
We report the initial results of the Brown Dwarf Spectroscopic Survey Gravity
Project, to study gravity sensitive features as indicators of youth in brown
dwarfs. Low-resolution (R~2000) J-band and optical (R~1000) observations using
NIRSPEC and LRIS at the W.M. Keck Observatory reveal transitions of TiO, VO, K
I, Na I, Cs I, Rb I, CaH, and FeH. By comparing these features in late-type
giants and in old field dwarfs we show that they are sensitive to the gravity
(g = GM/R^2) of the object. Using low-gravity spectral signatures as age
indicators, we observed and analyzed J-band and optical spectra of two young
brown dwarfs, G 196-3B (20-300 Myr) and KPNO Tau-4 (1-2 Myr), and two possible
low mass brown dwarfs in the sigma Orionis cluster (3-7 Myr). We report the
identification of the phi bands of TiO near 1.24 microns and the A-X band of VO
near 1.18 microns together with extremely weak J-band lines of K I in
KPNO-Tau4. This is the first detection of TiO and VO in the J-band in a
sub-stellar mass object. The optical spectrum of KPNO-Tau4 exhibits weak K I
and Na I lines, weak absorption by CaH, and strong VO bands, also signatures of
a lower gravity atmosphere. G 196-3B shows absorption features in both
wavelength regions like those of KPNO-Tau4 suggesting that its age and mass are
at the lower end of published estimates. Whereas sigma Ori 51 appears to be
consistent with a young sub-stellar object, sigma Ori 47 shows signatures of
high gravity most closely resembling an old L1.5/L0, and can not be a member of
the sigma Orionis cluster.Comment: 14 pages, 4 figures. To appear in the January 10, 2004 issue of the
Astrophysical Journa
Power Output of Fast and Slow Skeletal Muscles of MDX (Dystrophic) and Control Mice After Clenbuterol Treatment
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72380/1/j.1469-445X.2000.02018.x.pd
Post-Outburst Observations of V1647 Ori: Detection of a Brief Warm, Molecular Outflow
We present new observations of the fundamental ro-vibrational CO spectrum of
V1647 Ori, the young star whose recent outburst illuminated McNeil's Nebula.
Previous spectra, acquired during outburst in 2004 February and July, had shown
the CO emission lines to be broad and centrally peaked-similar to the CO
spectrum of a typical classical T Tauri star. In this paper, we present CO
spectra acquired shortly after the luminosity of the source returned to its
pre-outburst level (2006 February) and roughly one year later (2006 December
and 2007 February). The spectrum taken in 2006 February revealed blue-shifted
CO absorption lines superimposed on the previously observed CO emission lines.
The projected velocity, column density, and temperature of this outflowing gas
was 30 km/s, 3^{+2}_{-1}E18 cm^{-2$, and 700^{+300}_{-100} K, respectively. The
absorption lines were not observed in the 2006 December and 2007 February data,
and so their strengths must have decreased in the interim by a factor of 9 or
more. We discuss three mechanisms that could give rise to this unusual outflow.Comment: 14 pages, 2 figures, accepted for publication in ApJ
Abundance analysis for long period variables. Velocity effects studied with O-rich dynamic model atmospheres
(abbreviated) Measuring the surface abundances of AGB stars is an important
tool for studying the effects of nucleosynthesis and mixing in the interior of
low- to intermediate mass stars during their final evolutionary phases. The
atmospheres of AGB stars can be strongly affected by stellar pulsation and the
development of a stellar wind, though, and the abundance determination of these
objects should therefore be based on dynamic model atmospheres. We investigate
the effects of stellar pulsation and mass loss on the appearance of selected
spectral features (line profiles, line intensities) and on the derived
elemental abundances by performing a systematic comparison of hydrostatic and
dynamic model atmospheres. High-resolution synthetic spectra in the near
infrared range were calculated based on two dynamic model atmospheres (at
various phases during the pulsation cycle) as well as a grid of hydrostatic
COMARCS models. Equivalent widths of a selection of atomic and molecular lines
were derived in both cases and compared with each other. In the case of the
dynamic models, the equivalent widths of all investigated features vary over
the pulsation cycle. A consistent reproduction of the derived variations with a
set of hydrostatic models is not possible, but several individual phases and
spectral features can be reproduced well with the help of specific hydrostatic
atmospheric models. In addition, we show that the variations in equivalent
width that we found on the basis of the adopted dynamic model atmospheres agree
qualitatively with observational results for the Mira R Cas over its light
cycle. The findings of our modelling form a starting point to deal with the
problem of abundance determination in strongly dynamic AGB stars (i.e.,
long-period variables).Comment: 13 pages, 22 figures, accepted for publication in A&
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