2,290 research outputs found
Predicting local violence: Evidence from a panel survey in Liberia
Riots, murders, lynchings and other forms of local violence are costly to security
forces and society at large. Identifying risk factors and forecasting where local violence
is most likely to occur should help allocate scarce peacekeeping and policing resources.
Most forecasting exercises of this kind rely on structural or event data, but these have
many limitations in the poorest and most war-torn states, where the need for prediction
is arguably most urgent. We adopt an alternative approach, applying machine learning
techniques to original panel survey data from Liberia to predict collective, interpersonal
and extrajudicial violence two years into the future. We first train our models to
predict 2010 local violence using 2008 risk factors, then generate forecasts for 2012
before collecting new data. Our models achieve out-of-sample AUCs ranging from 0.65
to 0.74, depending on our specification of the dependent variable. The models also
draw our attention to risk factors different from those typically emphasized in studies
aimed at causal inference alone. For example, we find that while ethnic heterogeneity
and polarization are reliable predictors of local violence, adverse economic shocks are
not. Surprisingly, we also find that the risk of local violence is higher rather than
lower in communities where minority and majority ethnic groups share power. These
counterintuitive results illustrate the usefulness of prediction for generating new stylized
facts for future research to explain. Ours is one of just two attempts to forecast local
violence using survey data, and we conclude by discussing how our approach can be
replicated and extended as similar datasets proliferate
The Effect of Herbage Availability and Season of Year on the Rate of Liveweight Loss during Weighing of Fasting Ewe Lambs
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Application of Machine Learning Algorithms to Predict Body Condition Score from Liveweight Records of Mature Romney Ewes
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Mammary Gland Structures Are Not Affected by an Increased Growth Rate of Yearling Ewes Post-Weaning but Are Associated with Growth Rates of Singletons
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Galactic and Extragalactic Samples of Supernova Remnants: How They Are Identified and What They Tell Us
Supernova remnants (SNRs) arise from the interaction between the ejecta of a
supernova (SN) explosion and the surrounding circumstellar and interstellar
medium. Some SNRs, mostly nearby SNRs, can be studied in great detail. However,
to understand SNRs as a whole, large samples of SNRs must be assembled and
studied. Here, we describe the radio, optical, and X-ray techniques which have
been used to identify and characterize almost 300 Galactic SNRs and more than
1200 extragalactic SNRs. We then discuss which types of SNRs are being found
and which are not. We examine the degree to which the luminosity functions,
surface-brightness distributions and multi-wavelength comparisons of the
samples can be interpreted to determine the class properties of SNRs and
describe efforts to establish the type of SN explosion associated with a SNR.
We conclude that in order to better understand the class properties of SNRs, it
is more important to study (and obtain additional data on) the SNRs in galaxies
with extant samples at multiple wavelength bands than it is to obtain samples
of SNRs in other galaxiesComment: Final 2016 draft of a chapter in "Handbook of Supernovae" edited by
Athem W. Alsabti and Paul Murdin. Final version available at
https://doi.org/10.1007/978-3-319-20794-0_90-
Fifty years of spellchecking
A short history of spellchecking from the late 1950s to the present day, describing its development through dictionary lookup, affix stripping, correction, confusion sets, and edit distance to the use of gigantic databases
Is it safe? The restraint chair compared to traditional methods of restraint: A three hospital study
The Antibacterial Activity of Honey Derived from Australian Flora
Chronic wound infections and antibiotic resistance are driving interest in
antimicrobial treatments that have generally been considered complementary,
including antimicrobially active honey. Australia has unique native flora and
produces honey with a wide range of different physicochemical properties. In
this study we surveyed 477 honey samples, derived from native and exotic plants
from various regions of Australia, for their antibacterial activity using an
established screening protocol. A level of activity considered potentially
therapeutically useful was found in 274 (57%) of the honey samples, with
exceptional activity seen in samples derived from marri (Corymbia
calophylla), jarrah (Eucalyptus marginata) and
jellybush (Leptospermum polygalifolium). In most cases the
antibacterial activity was attributable to hydrogen peroxide produced by the
bee-derived enzyme glucose oxidase. Non-hydrogen peroxide activity was detected
in 80 (16.8%) samples, and was most consistently seen in honey produced
from Leptospermum spp. Testing over time found the hydrogen
peroxide-dependent activity in honey decreased, in some cases by 100%,
and this activity was more stable at 4°C than at 25°C. In contrast, the
non-hydrogen peroxide activity of Leptospermum honey samples
increased, and this was greatest in samples stored at 25°C. The stability of
non-peroxide activity from other honeys was more variable, suggesting this
activity may have a different cause. We conclude that many Australian honeys
have clinical potential, and that further studies into the composition and
stability of their active constituents are warranted
Effect of physical activity intervention on body composition in young children: influence of body mass index status and gender
The fate of redundant cues: Further analysis of the redundancy effect
Pearce, Dopson, Haselgrove, and Esber (Journal of Experimental Psychology: Animal Behavior Processes, 38, 167–179, 2012) conducted a series of experiments with rats and pigeons in which the conditioned responding elicited by two types of redundant cue was compared. One of these redundant cues was a blocked cue X from A+ AX+ training, whereas the other was cue Y from a simple discrimination BY+ CY–. Greater conditioned responding was elicited by X than by Y; we refer to this difference as the redundancy effect. To test an explanation of this effect in terms of comparator theory (Denniston, Savastano, & Miller, 2001), a single group of rats in Experiment 1 received training of the form A+ AX+ BY+ CY–, followed by an A– Y+ discrimination. Responding to the individual cues was tested both before and after the latter discrimination. In addition to a replication of the redundancy effect during the earlier test, we observed stronger responding to B than to X, both during the earlier test and, in contradiction of the theory, after the A– Y+ discrimination. In Experiment 2, a blocking group received A+ AX+, a continuous group received AX+ BX–, and a partial group received AX± BX± training. Subsequent tests with X again demonstrated the redundancy effect, but also revealed a stronger response in the partial than in the continuous group. This pattern of results is difficult to explain with error-correction theories that assume that stimuli compete for associative strength during conditioning. We suggest, instead, that the influence of a redundant cue is determined by its relationship with the event with which it is paired, and by the attention it is paid
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