5,734 research outputs found
THE ECONOMICS OF ILLEGAL FISHING: A BEHAVIORAL MODEL
This paper analyzes the microeconomic behavior of fishers responding to imperfectly enforced regulations through illegal fishing and efforts to avoid detection. An intraseasonal optimization model is analyzed to determine optimal (profit-maximizing) harvesting strategies at the individual fisher level in response to input controls (such as gear or labor usage) or output controls (individual harvest quotas). For each regulatory option, the analysis explores: (a) the manner by which enforcement affects individual decisions concerning fishing and avoidance activity, (b) the level of enforcement necessary to achieve specified conservation goals, and (c) the role of various behavioral parameters in determining fisher decisions. It is shown, in particular, that the nature of avoidance behavior plays a crucial role in determining fisher response to regulations. Broad implications of illegal behavior on the sustainability of fishery systems are also discussed.Resource /Energy Economics and Policy,
4d Conformal Field Theories and Strings on Orbifolds
We propose correspondences between 4d quantum field theories with N=2,1,0
(super)conformal invariance and Type IIB string theory on various orbifolds. We
argue using the spacetime string theory, and check using the beta functions
(exactly for N=2,1 and so far at 1-loop for the gauge couplings in the N=0
case), that these theories have conformal fixed lines. The latter case
potentially gives well-defined non-supersymmetric vacua of string theory, with
a mechanism for making the curvature and cosmological constant small at
nontrivial string coupling. We suggest a correspondence between
nonsupersymmetric conformal fixed lines and nonsupersymmetric string vacua with
vanishing vacuum energy.Comment: 11 pages, harvmac big. Reference adde
Analysis of ultrasonic transducers with fractal architecture
Ultrasonic transducers composed of a periodic piezoelectric composite are generally accepted as the design of choice in many applications. Their architecture is normally very regular and this is due to manufacturing constraints rather than performance optimisation. Many of these manufacturing restrictions no longer hold due to new production methods such as computer controlled, laser cutting, and so there is now freedom to investigate new types of geometry. In this paper, the plane wave expansion model is utilised to investigate the behaviour of a transducer with a self-similar architecture. The Cantor set is utilised to design a 2-2 conguration, and a 1-3 conguration is investigated with a Sierpinski Carpet geometry
Effects of the Temporal Variability of Storm Surges on Coastal Flooding
Assessments of flood exposure and risk are usually conducted for individual events with a specific peak water level and hydrograph, without considering variations in the temporal evolution (duration and intensity) of storm surges. Here we investigate the influence of temporal variability of storm surge events on flood characteristics in coastal zones, namely flood extent and inundation depth, and assess the associated flood exposure in terms of affected properties for the case of the municipality of Eckernförde, Germany. We use a nested hydrodynamic model to simulate five physically plausible, stochastically simulated storm surge events, with peak water levels corresponding to a univariate return period of 200 years and varying intensities. In a second step, the events are also combined with high-end sea-level rise projections corresponding to the RCP 8.5 scenario to analyze if the influence of temporal variability changes with rising sea-levels. Results show differences exceeding 5% in flood extent when comparing storm surges with the highest and lowest intensities. The number of properties exposed differs by approximately 20%. Differences in mean and maximum inundation depths are approximately 5%, both with and without sea-level rise. However, deviations in flood extent increase by more than 20%, depending on the sea-level rise projection, whereas differences in the number of exposed properties decrease. Our findings indicate that the temporal variability of storm surges can have considerable influence on flood extent and exposure in the study area. Taking into account that flood extent increases with rising sea-levels, we recommend that uncertainty related to the temporal variability of storm surges is represented in future flood risk assessments to ensure efficient planning and to provide a more comprehensive assessment of exposed infrastructure and assets
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Residential oil burners with low input and two stages firing
The residential oil burner market is currently dominated by the pressure-atomized, retention head burner. At low firing rates pressure atomizing nozzles suffer rapid fouling of the small internal passages, leading to bad spray patterns and poor combustion performance. To overcome the low input limitations of conventional burners, a low pressure air-atomized burner has been developed watch can operate at fining rates as low as 0.25 gallons of oil per hour (10 kW). In addition, the burner can be operated in a high/low fining rate mode. Field tests with this burner have been conducted at a fixed input rate of 0.35 gph (14 kW) with a side-wall vented boiler/water storage tank combination. At the test home, instrumentation was installed to measure fuel and energy flows and record trends in system temperatures. Laboratory efficiency testing with water heaters and boilers has been completed using standard single purpose and combined appliance test procedures. The tests quantify benefits due to low firing rates and other burner features. A two stage oil burner gains a strong advantage in rated efficiency while maintaining capacity for high domestic hot water and space heating loads
Torsion and the Gravity Dual of Parity Symmetry Breaking in AdS4/CFT3 Holography
We study four dimensional gravity with a negative cosmological constant
deformed by the Nieh-Yan torsional topological invariant with a
spacetime-dependent coefficient. We find an exact solution of the Euclidean
system, which we call the torsion vortex, having two asymptotic AdS4 regimes
supported by a pseudoscalar with a kink profile. We propose that the torsion
vortex is the holographic dual of a three dimensional system that exhibits
distinct parity breaking vacua. The torsion vortex represents a (holographic)
transition between these distinct vacua. We expect that from the boundary point
of view, the torsion vortex represents a `domain wall' between the two distinct
vacua.
From a bulk point of view, we point out an intriguing identification of the
parameters of the torsion vortex with those of an Abrikosov vortex in a Type I
superconductor. Following the analogy, we find that external Kalb-Ramond flux
then appears to support bubbles of flat spacetime within an asymptotically AdS
geometry.Comment: 26 pages, 4 figures; v2: minor improvements, references adde
Duality and Superconvergence Relation in Supersymmetric Gauge Theories
We investigate the phase structures of various N=1 supersymmetric gauge
theories including even the exceptional gauge group from the viewpoint of
superconvergence of the gauge field propagator. Especially we analyze in detail
whether a new type of duality recently discovered by Oehme in gauge
theory coupled to fundamental matter fields can be found in more general gauge
theories with more general matter representations or not. The result is that in
the cases of theories including matter fields in only the fundamental
representation, Oehme's duality holds but otherwise it does not. In the former
case, superconvergence relation might give good criterion to describe the
interacting non-Abelian Coulomb phase without using some information from dual
magnetic theory.Comment: 20 pages, LaTe
Exact Scattering States of Dirac-Born-Infeld Equation with Constant Background Fields
Exact solutions to the Dirac-Born-Infeld equation, which describes
scatterings of localized wave packets in the presence of constant background
fields, are derived in this paper.Comment: 18 pages, latex, no figure
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Beagle 2: Seeking the signatures of life on Mars
ESA's Beagle 2 lander will land on Mars to search for signatures of present and past life. A Gas Analysis Package (GAP) with a mass spectrometer, XRF, Mossbauer, stereo cameras, microscope, environmental sensors, rock corer/grinder, and a Mole attachment are on the lander
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