707 research outputs found
Cure Violence: A Public Health Model to Reduce Gun Violence
Scholars and practitioners alike in recent years have suggested that real and lasting progress in the fight against gun violence requires changing the social norms and attitudes that perpetuate violence and the use of guns. The Cure Violence model is a public health approach to gun violence reduction that seeks to change individual and community attitudes and norms about gun violence. It considers gun violence to be analogous to a communicable disease that passes from person to person when left untreated. Cure Violence operates independently of, while hopefully not undermining, law enforcement. In this article, we describe the theoretical basis for the program, review existing program evaluations, identify several challenges facing evaluators, and offer directions for future research
Improved Dairy Cattle: Impact and Distribution in Rural Tanzanian Communities
Improved dairy cattle are recognized as an integral part of improving the livelihoods for the rural and urban poor in developing countries. The aim of this research was to measure impact, reveal challenges, map distribution, and establish recommendations for moving forward in improved livestock distribution initiatives. The methods consisted of a hybrid model using both quantitative and qualitative modalities, especially focusing on personal interviews, focus group discussions, field observation, and GIS data capturing. GIS based comparisons could not be made because of a lack of available GIS demographic data for the area. The combined modalities approach (especially the in-depth interviews and FGD) allowed an accurate picture of impact to emerge. Overall IDC had an overwhelmingly positive effect on the lives of the owners especially in the areas of increased income and nutrition for the family. The main challenges faced by owners of IDC were the higher disease prevalence found in the IDC (Friesian and Ayrshire), susceptibility to pests (tsetse flies and ticks), and lack of affordable veterinary access. Increases medical training of the improved livestock owners was suggested
Exercise Beliefs During Pregnancy in a Predominantly Low-Income, Urban Minority Population
In 2002, and reaffirmed in 2009, The American College of Obstetricians and Gynecologists recommended that healthy pregnant women exercise for at least thirty minutes most days of the week. Exercise during a healthy pregnancy is safe and has many maternal and fetal benefits. Identified benefits include management of weight gain, improvement in mood, and preparation for labor. Previous research has evaluated women’s beliefs and practices of exercise in pregnancy, but it has focused on affluent, ethnic majority populations. This survey study was performed to assess beliefs about exercise in pregnancy in a predominantly low-income, urban minority population.https://jdc.jefferson.edu/cwicposters/1031/thumbnail.jp
Fair Allocation of Two Types of Chores
We consider the problem of fair allocation of indivisible chores under
additive valuations. We assume that the chores are divided into two types and
under this scenario, we present several results. Our first result is a new
characterization of Pareto optimal allocations in our setting, and a
polynomial-time algorithm to compute an envy-free up to one item (EF1) and
Pareto optimal allocation. We then turn to the question of whether we can
achieve a stronger fairness concept called envy-free up any item (EFX). We
present a polynomial-time algorithm that returns an EFX allocation. Finally, we
show that for our setting, it can be checked in polynomial time whether an
envy-free allocation exists or not
Similar temperature responses suggest future climate warming will not alter partitioning between denitrification and anammox in temperate marine sediments
Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Global Change Biology 23 (2017): 331-340, doi:10.1111/gcb.13370.Removal of biologically available nitrogen (N) by the microbially mediated processes
denitrification and anaerobic ammonium oxidation (anammox) affects ecosystem N availability.
Although few studies have examined temperature responses of denitrification and anammox,
previous work suggests that denitrification could become more important than anammox in
response to climate warming. To test this hypothesis, we determined whether temperature
responses of denitrification and anammox differed in shelf and estuarine sediments from coastal
Rhode Island over a seasonal cycle. The influence of temperature and organic C availability was
further assessed in a 12-week laboratory microcosm experiment. Temperature responses, as
characterized by thermal optima (Topt) and apparent activation energy (Ea), were determined by
measuring potential rates of denitrification and anammox at 31 discrete temperatures ranging
from 3 to 59°C. With a few exceptions, Topt and Ea of denitrification and anammox did not differ
in Rhode Island sediments over the seasonal cycle. In microcosm sediments, Ea was
somewhat lower for anammox compared to denitrification across all treatments. However,
Topt did not differ between processes, and neither Ea nor Topt changed with warming or carbon
addition. Thus, the two processes behaved similarly in terms of temperature response, and this
response was not influenced by warming. This led us to reject the hypothesis that anammox is
more cold-adapted than denitrification in our study system. Overall, our study suggests that
temperature responses of both processes can be accurately modeled for temperate regions in the
future using a single set of parameters, which are likely not to change over the next century as a
result of predicted climate warming. We further conclude that climate warming will not directly
alter the partitioning of N flow through anammox and denitrification.This material is based upon work supported by the National Science Foundation
under Grant No. OCE-0852289 to JJR and OCE-0852263, OCE-0927400 and OCE1238212 to
AEG, and Rhode Island Sea Grant to JJR.2017-05-2
Effects of experimental warming and carbon addition on nitrate reduction and respiration in coastal sediments
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 125 (2015): 81-95, doi:10.1007/s10533-015-0113-4.Climate change may have differing effects on microbial processes that control coastal N
availability. We conducted a microcosm experiment to explore effects of warming and carbon
availability on nitrate reduction pathways in marine sediments. Sieved continental shelf
sediments were incubated for 12 weeks under aerated seawater amended with nitrate (~50 μM),
at winter (4°C) or summer (17°C) temperatures, with or without biweekly particulate organic C
additions. Treatments increased diffusive oxygen consumption as expected, with somewhat
higher effects of C addition compared to warming. Combined warming and C addition had the
strongest effect on nitrate flux across the sediment water interface, with a complete switch early
in the experiment from influx to sustained efflux. Supporting this result, vial incubations with
added 15N-nitrate indicated that C addition stimulated potential rates of dissimilatory nitrate
reduction to ammonium (DNRA), but not denitrification. Overall capacity for both
denitrification and DNRA was reduced in warmed treatments, possibly reflecting C losses due to
increased respiration with warming. Anammox potential rates were much lower than DNRA or
denitrification, and were slightly negatively affected by warming or C addition. Overall, results
indicate that warming and C addition increased ammonium production through remineralization
and possibly DNRA. This stimulated nitrate production through nitrification, but without a
comparable increase in nitrate consumption through denitrification. The response to C of
potential DNRA rates over denitrification, along with a switch to nitrate efflux, raises the
possibility that DNRA is an important and previously overlooked source of internal N cycling in
shelf sediments.This material is based upon work supported by the National Science Foundation by OCE-
0852289 to JJR and OCE-0852263 and OCE-0927400 to AEG, and Rhode Island Sea Grant to
JJR
Searching for faint companions with VLTI/PIONIER. II. 92 main sequence stars from the Exozodi survey
The Exozodi survey aims to determine the occurrence rate of bright
exozodiacal discs around nearby main sequence stars using infrared
interferometry. Although the Exozodi survey targets have been carefully
selected to avoid the presence of binary stars, the results of this survey can
still be biased by the presence of unidentified stellar companions. Using the
PIONIER data set collected within the Exozodi survey, we aim to search for the
signature of point-like companions around the Exozodi target stars. We use both
the closure phases and squared visibilities collected by PIONIER to search for
companions within the ~100 mas interferometric field of view. The presence of a
companion is assessed by computing the goodness of fit to the data for a series
of binary models with various separations and contrasts. Five stellar
companions are resolved for the first time around five A-type stars: HD 4150,
HD 16555, HD 29388, HD 202730, and HD 224392 (although the companion to HD
16555 was independently resolved by speckle interferometry while we were
carrying out the survey). In the most likely case of main sequence companions,
their spectral types range from A5V to K4V. Three of these stars were already
suspected to be binaries from Hipparcos astrometric measurements, although no
information was available on the companions themselves so far. In addition to
debiasing the statistics of the Exozodi survey, these results can also be used
to revise the fraction of visual binaries among A-type stars, suggesting that
an extra ~13% A-type stars are visual binaries in addition to the ones detected
in previous direct imaging surveys. We estimate that about half the population
of nearby A-type stars could be resolved as visual binaries using a combination
of state-of-the-art interferometry and single-aperture imaging, and we suggest
that a significant fraction of these binaries remains undetected to date.Comment: Accepted for publication in A&
A near-infrared interferometric survey of debris-disc stars. IV. An unbiased sample of 92 southern stars observed in H-band with VLTI/PIONIER
Context. Detecting and characterizing circumstellar dust is a way to study
the architecture and evolution of planetary systems. Cold dust in debris disks
only traces the outer regions. Warm and hot exozodiacal dust needs to be
studied in order to trace regions close to the habitable zone.
Aims. We aim to determine the prevalence and to constrain the properties of
hot exozodiacal dust around nearby main-sequence stars.
Methods. We search a magnitude limited (H < 5) sample of 92 stars for bright
exozodiacal dust using our VLTI visitor instrument PIONIER in the H-band. We
derive statistics of the detection rate with respect to parameters such as the
stellar spectral type and age or the presence of a debris disk in the outer
regions of the systems. We derive more robust statistics by combining our
sample with the results from our CHARA/FLUOR survey in the K-band. In addition,
our spectrally dispersed data allows us to put constraints on the emission
mechanism and the dust properties in the detected systems.
Results. We find an over-all detection rate of bright exozodiacal dust in the
H-band of 11% (9 out of 85 targets) and three tentative detections. The
detection rate decreases from early type to late type stars and increases with
the age of the host star. We do not confirm the tentative correlation between
the presence of cold and hot dust found in our earlier analysis of the FLUOR
sample alone. Our spectrally dispersed data suggest that either the dust is
extremely hot or the emission is dominated by the scattered light in most
cases. The implications of our results for the target selection of future
terrestrial planet finding missions using direct imaging are discussed.Comment: 20 pages, 16 figures, 4 tables, updated references and minor changes
to the text, accepted for publication in A&
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