6,422 research outputs found
The Role of Information and Values in the Participatory Analysis of Social-Ecological Systems
Objectivism, supposing that information is âout thereâ and can be accessed through appropriate research methods, is a valuable and unavoidable initial stance in field work. However, even within an objectivist paradigm, information gathered from field work can never be accepted uncritically, however rigorous the research methodology, since each step of the process from the choice of methodology onwards is driven and circumscribed by the values and beliefs of the participants.
In response to the growing threat of climatic change researchers are increasingly utilising social surveys to access information on human-environment interactions or the operation of âsocial-ecologicalâ systems, in order to preserve key functions into the future. This paper explores the sources of uncertainty which emerge as simple environmental data transfers from participant to researcher. In particular, it considers the role that values can play in determining the quality of participant-reported quantitative environmental data, presented within the framework of Shannonâs standard communication model
Stability of Homomorphisms, Coverings and Cocycles I: Equivalence
This paper is motivated by recent developments in group stability, high
dimensional expansion, local testability of error correcting codes and
topological property testing. In Part I, we formulate and motivate three
stability problems: 1. Homomorphism stability: Are almost homomorphisms close
to homomorphisms? 2. Covering stability: Are almost coverings of a cell complex
close to genuine coverings of it? 3. Cocycle stability: Are 1-cochains whose
coboundary is small close to 1-cocycles? We then prove that these three
problems are equivalent.Comment: 32 page
The HDF-North SCUBA Super-map II: Multi-wavelength properties
We present radio, optical and X-ray detected counterparts to the sub-mm
sources found using SCUBA in the Hubble Deep Field North region (GOODS-N). A
new counterpart identification statistic is developed to identify properties of
galaxies detected at other wavelengths that can be used to aid counterpart
identification. We discriminate between criteria that can be used to pre-select
sub-mm bright objects, and those that identify the counterpart to a known
sub-mm object. Optically faint galaxies detected in the deepest 1.4 GHz radio
continuum maps are the only effective way of pre-selecting SCUBA galaxies, and
radio sources are the best way to identify counterparts to known sub-mm
detections. Looking at radio spectral indices, only the steeper sources
(indicative of star formation) are detected in the sub-mm. Although we find
several X-ray identifications, we show that deep Chandra images do not
contribute to counterpart identifications, since in all cases they are already
detected in the more easily obtained VLA radio maps. We also find find no
evidence for clustering between Chandra and SCUBA sources in this field. For a
known SCUBA position, the reddest source tends to be the correct association,
although we can find no cut on colour, magnitude, or clustering property that
efficiently pre-selects for SCUBA sources. 15 micron ISO sources are
statistically detected by SCUBA, but the limiting mid-IR flux is not low enough
to provide useful constraints. We present postage stamp strips for each SCUBA
detection in separate bands from X-ray to radio, providing direct visual
evidence that approximately half of the sub-mm sources in this field remain
unidentified, despite an abundance of deep multi-wavelength data.Comment: Accepted for publication in MNRAS. High resolution version available
at http://www.submm.caltech.edu/~borys/paper
The Compositional Structure of the Asteroid Belt
The past decade has brought major improvements in large-scale asteroid
discovery and characterization with over half a million known asteroids and
over 100,000 with some measurement of physical characterization. This explosion
of data has allowed us to create a new global picture of the Main Asteroid
Belt. Put in context with meteorite measurements and dynamical models, a new
and more complete picture of Solar System evolution has emerged. The question
has changed from "What was the original compositional gradient of the Asteroid
Belt?" to "What was the original compositional gradient of small bodies across
the entire Solar System?" No longer is the leading theory that two belts of
planetesimals are primordial, but instead those belts were formed and sculpted
through evolutionary processes after Solar System formation. This article
reviews the advancements on the fronts of asteroid compositional
characterization, meteorite measurements, and dynamical theories in the context
of the heliocentric distribution of asteroid compositions seen in the Main Belt
today. This chapter also reviews the major outstanding questions relating to
asteroid compositions and distributions and summarizes the progress and current
state of understanding of these questions to form the big picture of the
formation and evolution of asteroids in the Main Belt. Finally, we briefly
review the relevance of asteroids and their compositions in their greater
context within our Solar System and beyond.Comment: Accepted chapter in Asteroids IV in the Space Science Series to be
published Fall 201
Orientation cues for high-flying nocturnal insect migrants: do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?
Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity
and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction
Fact: Many SCUBA galaxies harbour AGNs
Deep SCUBA surveys have uncovered a large population of ultra-luminous
galaxies at z>1. These sources are often assumed to be starburst galaxies, but
there is growing evidence that a substantial fraction host an AGN (i.e., an
accreting super-massive black hole). We present here possibly the strongest
evidence for this viewpoint to date: the combination of ultra-deep X-ray
observations (the 2 Ms Chandra Deep Field-North) and deep optical spectroscopic
data. We argue that upward of 38% of bright (f850um>=5mJy) SCUBA galaxies host
an AGN, a fraction of which are obscured QSOs (i.e., L_X>3x10^{44} erg/s).
However, using evidence from a variety of analyses, we argue that in almost all
cases the AGNs are not bolometrically important (i.e., <20%). Thus, star
formation appears to dominate their bolometric output. A substantial fraction
of bright SCUBA galaxies show evidence for binary AGN activity. Since these
systems appear to be interacting and merging at optical/near-IR wavelengths,
their super-massive black holes will eventually coalesce.Comment: Invited contribution - 10 pages, 4 figures, to appear in the
Proceedings of the ESO/USM/MPE Workshop on "Multiwavelength Mapping of Galaxy
Formation and Evolution", eds. R. Bender and A. Renzin
How has the Opioid Overdose Crisis Affected Child Maltreatment in the U.S.?
This brief summarizes results from a study examining the association between U.S. county-level opioid mortality rates and child maltreatment rates from 2007 to 2017. Places with higher opioid overdose mortality rates have higher rates of child maltreatment. Poverty makes this problem worse - where the proportion of families in poverty increases, the association between fatal opioid overdose rates and child maltreatment also increases. Findings suggest that intervening in opioid use by reducing poverty has the potential to markedly decrease the incidence of child maltreatment
Americas Forgotten Orphans: An Urgent Call for the White House and Congress to Address Childhood Bereavement
Today, more than 2.2 million children under the age of eighteen in the United States have experienced the death of a co-resident parent. As a result of their loss, many of these children face significant physical, social, and economic hardships for the rest of their lives.In this first-of-its-kind report, we examine the current and historical trends in childhood bereavement and discover it is an epidemic hiding in plain sight impacting every state, race, and ethnicity in the nation.Beyond discovering this crisis, we provide a road map for federal lawmakers, philanthropists, and other public leaders to create equal, healthy, and prosperous futures for all our nation's orphans
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