524 research outputs found
The use of semi-structured interviews for the characterisation of farmer irrigation practices
For the development of sustainable and realistic water security, generating
information on the behaviours, characteristics, and drivers of users, as well
as on the resource itself, is essential. In this paper we present a
methodology for collecting qualitative and quantitative data on water use
practices through semi-structured interviews. This approach facilitates the
collection of detailed information on actors' decisions in a convenient and
cost-effective manner. Semi-structured interviews are organised around a
topic guide, which helps lead the conversation in a standardised way while
allowing sufficient opportunity for relevant issues to emerge. In addition,
they can be used to obtain certain types of quantitative data. While not as
accurate as direct measurements, they can provide useful information on local
practices and users' insights. We present an application of the methodology
on farmer water use in two districts in the state of Uttar Pradesh in
northern India. By means of 100 farmer interviews, information was collected on
various aspects of irrigation practices, including irrigation water volumes,
irrigation cost, water source, and their spatial variability. Statistical
analyses of the information, along with data visualisation, are also
presented, indicating a significant variation in irrigation practices both within and
between districts. Our application shows that semi-structured interviews are
an effective and efficient method of collecting both qualitative and
quantitative information for the assessment of drivers, behaviours, and their
outcomes in a data-scarce region. The collection of this type of data could
significantly improve insights on water resources, leading to more realistic
management options and increased water security in the future
Advanced manufacturing development of a composite empennage component for L-1011 aircraft
This is the final report of technical work conducted during the fourth phase of a multiphase program having the objective of the design, development and flight evaluation of an advanced composite empennage component manufactured in a production environment at a cost competitive with those of its metal counterpart, and at a weight savings of at least 20 percent. The empennage component selected for this program is the vertical fin box of the L-1011 aircraft. The box structure extends from the fuselage production joint to the tip rib and includes front and rear spars. During Phase 4 of the program, production quality tooling was designed and manufactured to produce three sets of covers, ribs, spars, miscellaneous parts, and subassemblies to assemble three complete ACVF units. Recurring and nonrecurring cost data were compiled and documented in the updated producibility/design to cost plan. Nondestruct inspections, quality control tests, and quality acceptance tests were performed in accordance with the quality assurance plan and the structural integrity control plan. Records were maintained to provide traceability of material and parts throughout the manufacturing development phase. It was also determined that additional tooling would not be required to support the current and projected L-1011 production rate
Orbits of Near-Earth Asteroid Triples 2001 SN263 and 1994 CC: Properties, Origin, and Evolution
Three-body model fits to Arecibo and Goldstone radar data reveal the nature
of two near-Earth asteroid triples. Triple-asteroid system 2001 SN263 is
characterized by a primary of ~10^13 kg, an inner satellite ~1% as massive
orbiting at ~3 primary radii in ~0.7 days, and an outer satellite ~2.5% as
massive orbiting at ~13 primary radii in ~6.2 days. 1994 CC is a smaller system
with a primary of mass ~2.6 \times 10^11 kg and two satellites ~2% and ~1% as
massive orbiting at distances of ~5.5 and ~19.5 primary radii. Their orbital
periods are ~1.2 and ~8.4 days. Examination of resonant arguments shows that
the satellites are not currently in a mean-motion resonance. Precession of the
apses and nodes are detected in both systems (2001 SN263 inner body:
d{\varpi}/dt ~1.1 deg/day, 1994 CC inner body: d{\varpi}/dt ~ -0.2 deg/day),
which is in agreement with analytical predictions of the secular evolution due
to mutually interacting orbits and primary oblateness. Nonzero mutual
inclinations between the orbital planes of the satellites provide the best fits
to the data in both systems (2001 SN263: ~14 degrees, 1994 CC: ~16 degrees).
Our best-fit orbits are consistent with nearly circular motion, except for 1994
CC's outer satellite which has an eccentric orbit of e ~ 0.19. We examine
several processes that can generate the observed eccentricity and inclinations,
including the Kozai and evection resonances, past mean-motion resonance
crossings, and close encounters with terrestrial planets. In particular, we
find that close planetary encounters can easily excite the eccentricities and
mutual inclinations of the satellites' orbits to the currently observed values.Comment: 17 pages, accepted to Astronomical Journa
PAID TO PUMP: How a tax credit could discourage conservation of the High Plains Aquifer
In 1965’s United States v. Shurbet case, an irrigator from Texas asserted his claim for a depletion tax deduction for groundwater pumped from the High Plains Aquifer. He argued that the unique conditions of the southern High Plains region - a plateau where the shallow aquifer is recharged only through precipitation at a slow rate - meant the groundwater resource would be depleted in time. The state argued that groundwater was not fundamentally an exhaustible natural deposit, but the Supreme Court concluded the tax deduction was appropriate given the “peculiar” conditions in the area. It was stated the decision was not meant to establish a precedent regarding cost depletion of groundwater. The findings of the Shurbet case were intended to be limited to the southern High Plains region. However, in a 1980 lawsuit against the IRS, the Gigot brothers of Kansas sought to expand the deduction to allow depletion of the aquifer beneath their 30,000 acre farm in Kansas. The case was settled in the district court with a ruling allowing the brothers’ deductions to continue, thereby extending the Shurbet decision to include all landowners extracting from the approximately 174,000 square miles of land overlying the High Plains Aquifer. Currently, the estimated value of the credit is highest in parts of northern Texas, eastern Colorado, western Kansas, and south central Nebraska
Shifting up a gear with iDNA: From mammal detection events to standardised surveys
Invertebrate-derived DNA (iDNA), in combination with high throughput sequencing, has been proposed as a cost-efficient and powerful tool to survey vertebrate species. Previous studies, however, have only provided evidence that vertebrates can be detected using iDNA, but have not taken the next step of placing these detection events within a statistical framework that allows for robust biodiversity assessments. Here, we compare concurrent iDNA and camera-trap surveys. Leeches were repeatedly collected in close vicinity to 64 camera-trap stations in Sabah, Malaysian Borneo. We analyse iDNA-derived mammalian detection events in a modern occupancy model that accounts for imperfect detection and compare the results with those from occupancy models parameterised with camera-trap-derived detection events. We also combine leech-iDNA and camera-trap data in a single occupancy model. We found consistent estimates of occupancy probabilities produced by our camera-trap and leech datasets. This indicates that the metabarcoding of leech-iDNA method provides reasonable estimates of occupancy and may be a suitable method for studying and monitoring mammal species in tropical rainforests. However, we also show that a more extensive collection of leeches would be needed to assess mammal biodiversity with a robustness similar to that of camera traps. As certain taxa were only detected in leeches, we see great potential in complementing camera-trap studies with the iDNA approach, as long as the collection of leeches follows a robust and standardised sampling scheme. Synthesis and applications. Here, we describe an approach to analyse detection records of mammals derived from leech samples using an occupancy framework that accounts for leech-specific factors influencing the detection probability. We further combined camera trap and leech data, which lead to increased confidence in occupancy estimates. Our approach is not restricted to the processing of leech samples, but can be used for the analysis of other invertebrate DNA and environmental DNA data. Our study is the first step to shift the application of invertebrate DNA studies from opportunistic ad-hoc collections to the systematic surveys required for long-term management of wildlife populations
Meeting reports: Research on Coupled Human and Natural Systems (CHANS): Approach, Challenges, and Strategies
Understanding the complexity of human–nature interactions is central to the quest for both human well-being and global sustainability. To build an understanding of these interactions, scientists, planners, resource managers, policymakers, and communities increasingly are collaborating across wide-ranging disciplines and knowledge domains. Scientists and others are generating new integrated knowledge on top of their requisite specialized knowledge to understand complex systems in order to solve pressing environmental and social problems (e.g., Carpenter et al. 2009). One approach to this sort of integration, bringing together detailed knowledge of various disciplines (e.g., social, economic, biological, and geophysical), has become known as the study of Coupled Human and Natural Systems, or CHANS (Liu et al. 2007a, b).
In 2007 a formal standing program in Dynamics of Coupled Natural and Human Systems was created by the U.S. National Science Foundation. Recently, the program supported the launch of an International Network of Research on Coupled Human and Natural Systems (CHANS-Net.org). A major kick-off event of the network was a symposium on Complexity in Human–Nature Interactions across Landscapes, which brought together leading CHANS scientists at the 2009 meeting of the U.S. Regional Association of the International Association for Landscape Ecology in Snowbird, Utah. The symposium highlighted original and innovative research emphasizing reciprocal interactions between human and natural systems at multiple spatial, temporal, and organizational scales. The presentations can be found at ‹http://chans- net.org/Symposium_2009.aspx›. The symposium was accompanied by a workshop on Challenges and Opportunities in CHANS Research. This article provides an overview of the CHANS approach, outlines the primary challenges facing the CHANS research community, and discusses potential strategies to meet these challenges, based upon the presentations and discussions among participants at the Snowbird meeting
Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV
We present results of searches for diphoton resonances produced both
inclusively and also in association with a vector boson (W or Z) using 100
pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on
the product of cross section times branching ratio for both p\bar
p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive
production to the expectations from heavy sgoldstinos we derive limits on the
supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the
sgoldstino mass and the choice of other parameters. Also, using a NLO
prediction for the associated production of a Higgs boson with a W or Z boson,
we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we
set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which
couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82
GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure
Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron Collider
We report a measurement of the strong coupling constant, ,
extracted from inclusive jet production in collisions at
1800 GeV. The QCD prediction for the evolution of with
jet transverse energy is tested over the range 40<<450 GeV using
for the renormalization scale. The data show good agreement with QCD in
the region below 250 GeV. In the text we discuss the data-theory comparison in
the region from 250 to 450 GeV. The value of at the mass of the
boson averaged over the range 40<<250 GeV is found to be
. The associated theoretical uncertainties are mainly due to the choice
of renormalization scale (^{+6%}_{-4%}) and input parton distribution
functions (5%).Comment: 7 pages, 3 figures, using RevTeX. Submitted to Physical Review
Letter
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