4,608 research outputs found
A Survey of Federal Tax Collection Procedure: Rights and Remedies of Taxpayers and the Internal Revenue Service
The Economics of Regulations on Hen Housing in California
Beginning January 1, 2015, conventional cage housing for egg-laying hens is scheduled to be prohibited in California. We consider the economic implications of the new hen housing regulations on the California shell egg industry. Our data show that egg production is more costly using noncage systems than conventional cages. The main result of the new regulations will be a drastic reduction in the number of eggs produced in California, a large increase in egg shipments from out of state, little if any change in hen housing for eggs consumed in California, and little change in egg prices in California.animal welfare regulation, hen housing, egg supply, egg prices, egg costs of production, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Consumer/Household Economics, Farm Management, Livestock Production/Industries, Production Economics, Productivity Analysis, Q11, Q18,
Mitigation of artifacts due to isolated acoustic heterogeneities in photoacoustic computed tomography using a variable data truncation-based reconstruction method
Photoacoustic computed tomography (PACT) is an emerging computed imaging
modality that exploits optical contrast and ultrasonic detection principles to
form images of the absorbed optical energy density within tissue. If the object
possesses spatially variant acoustic properties that are unaccounted for by the
reconstruction method, the estimated image can contain distortions. While
reconstruction methods have recently been developed to compensate for this
effect, they generally require the object's acoustic properties to be known a
priori. To circumvent the need for detailed information regarding an object's
acoustic properties, we previously proposed a half-time reconstruction method
for PACT. A half-time reconstruction method estimates the PACT image from a
data set that has been temporally truncated to exclude the data components that
have been strongly aberrated. However, this method can be improved upon when
the approximate sizes and locations of isolated heterogeneous structures, such
as bones or gas pockets, are known. To address this, we investigate PACT
reconstruction methods that are based on a variable data truncation (VDT)
approach. The VDT approach represents a generalization of the half-time
approach, in which the degree of temporal truncation for each measurement is
determined by the distance between the corresponding ultrasonic transducer
location and the nearest known bone or gas void location. Computer-simulated
and experimental data are employed to demonstrate the effectiveness of the
approach in mitigating artifacts due to acoustic heterogeneities
Differential temporal beta‐diversity patterns of native and non‐native arthropod species in a fragmented native forest landscape
An important factor that hinders the management of non‐native species is a general lack of information regarding the biogeography of non‐natives, and, in particular, their rates of turnover. Here, we address this research gap by analysing differences in temporal beta‐diversity (using both pairwise and multiple‐time dissimilarity metrics) between native and non‐native species, using a novel time‐series dataset of arthropods sampled in native forest fragments in the Azores. We use a null model approach to determine whether temporal beta‐diversity was due to deterministic processes or stochastic colonisation and extinction events, and linear modelling selection to assess the factors driving variation in temporal beta‐diversity between plots. In accordance with our predictions, we found that the temporal beta‐diversity was much greater for non‐native species than for native species, and the null model analyses indicated that the turnover of non‐native species was due to stochastic events. No predictor variables were found to explain the turnover of native or non‐native species. We attribute the greater turnover of non‐native species to source‐sink processes and the close proximity of anthropogenic habitats to the fragmented native forest plots sampled in our study. Thus, our findings point to ways in which the study of turnover can be adapted for future applications in habitat island systems. The implications of this for biodiversity conservation and management are significant. The high rate of stochastic turnover of non‐native species indicates that attempts to simply reduce the populations of non‐native species in situ within native habitats may not be successful. A more efficient management strategy would be to interrupt source‐sink dynamics by improving the harsh boundaries between native and adjacent anthropogenic habitats.Portuguese FCT‐NETBIOME – ISLANDBIODIV grant 0003/2011.info:eu-repo/semantics/publishedVersio
Ten Year Follow Up of a Psychiatry Residency Program Merger
Objective: To report on the successful merger of a civilian and military psychiatry residency. Methods: The reasons for and the history of the merger between the University of Texas Health Science Center at San Antonio and Wilford Hall Air Force Medical Center psychiatry residencies is described. Results: After some false starts, a bottom-up approach was implemented by first merging seminars, then rotations. Conclusions: Combining two psychiatry residencies in order to capitalize on both their strengths can yield a product even greater than the sum of their two programs and the key to a lasting merger is to start with two independently successful programs with different and complementary strengths
Verification of TG-61 dose for synchrotron-produced monochromatic x-ray beams using fluence-normalized MCNP5 calculations
Ion chamber dosimetry is being used to calibrate dose for cell irradiations
designed to investigate photoactivated Auger electron therapy at the Louisiana
State University CAMD synchrotron facility. This study performed a dosimetry
intercomparison for synchrotron-produced monochromatic x-ray beams at 25 and 35
keV. Ion chamber depth-dose measurements in a PMMA phantom were compared with
the product of MCNP5 Monte Carlo calculations of dose per fluence and measured
incident fluence. Monochromatic beams of 25 and 35 keV were generated on the
tomography beamline at CAMD. A cylindrical, air-equivalent ion chamber was used
to measure the ionization created in a 10x10x10-cm3 PMMA phantom for depths
from 0.6 to 7.7 cm. The American Association of Physicists in Medicine TG-61
protocol was applied to convert measured ionization into dose. Photon fluence
was determined using a NaI detector to make scattering measurements of the beam
from a thin polyethylene target at angles 30 degrees to 60 degrees.
Differential Compton and Rayleigh scattering cross sections obtained from
xraylib, an ANSI C library for x-ray-matter interactions, were applied to
derive the incident fluence. MCNP5 simulations of the irradiation geometry
provided the dose deposition per photon fluence as a function of depth in the
phantom. At 25 keV the fluence-normalized MCNP5 dose overestimated the
ion-chamber measured dose by an average of 7.2+/-3.0% to 2.1+/-3.0% for PMMA
depths from 0.6 to 7.7 cm, respectively. At 35 keV the fluence-normalized MCNP5
dose underestimated the ion-chamber measured dose by an average of 1.0+/-3.4%
to 2.5+/-3.4%, respectively. These results showed that TG-61 ion chamber
dosimetry, used to calibrate dose output for cell irradiations, agreed with
fluence-normalized MCNP5 calculations to within approximately 7% and 3% at 25
and 35 keV, respectively.Comment: 22 pages, 5 figure
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