3,170 research outputs found
New Jersey Commercial Loan Opinion Letters: The Remedies Opinion, Asset-Based Secured Transactions Opinions & Related Exceptions, Qualifications & Assumptions
Estimating Heterogeneous Production in Fisheries
Stochastic production frontier models are used extensively in the agricultural and resource economics literature to estimate production functions and technical efficiency, as well as to guide policy. Traditionally these models assume that each agent’s production can be specified as a representative, homogeneous function. This paper proposes the synthesis of a latent class regression and an agricultural production frontier model to estimate technical efficiency while allowing for the possibility of production heterogeneity. We use this model to estimate a latent class production function and efficiency measures for vessels in the Northeast Atlantic herring fishery. Our results suggest that traditional measures of technical efficiency may be incorrect, if heterogeneity of agricultural production exists
Estimating Heterogeneous Production in Fisheries
Stochastic production frontier models are used extensively in the agricultural and resource economics literature to estimate production functions and technical efficiency, as well as to guide policy. Traditionally these models assume that each agent\u27s production can be specified as a representative, homogeneous function. This paper proposes the synthesis of a latent class regression and an agricultural production frontier model to estimate technical efficiency while allowing for the possibility of production heterogeneity. We use this model to estimate a latent class production function and efficiency measures for vessels in the Northeast Atlantic herring fishery. Our results suggest that traditional measures of technical efficiency may be incorrect, if heterogeneity of agricultural production exists
The application of metacommunity theory to the management of riverine ecosystems
River managers strive to use the best available science to sustain biodi versity and ecosystem function. T o achieve this goal requires consideration of processes at different scales. Metacommunity theory describes how multiple species from differ- ent communities potentially interact with local-scale environmental drivers to influ- ence population dynamics and community structure. However, this body of knowledge has only rarely been used to inform management practices for river ecosystems. In this article, we present a conceptual model outlining how the metacommunity processes of local niche sorting and dispersal can influence the outcomes of management interventions and provide a series of specific recommen- dations for applying these ideas as well as research needs. In all cases, we identify situations where traditional approaches to riverine management could be enhanced by incorporating an understanding of metacommunity dynamics. A common theme is developing guidelines for assessing the metacommunity context of a site or region, evaluating how that context may affect the desired outcome, and incorporat- ing that understanding into the planning process and methods used. To maximize the effectiveness of management activities, scientists, and resource managers should update the toolbox of approaches to riverine management to reflect theoretical advances in metacommunity ecology
Photometric Accretion Signatures Near the Substellar Boundary
Multi-epoch imaging of the Orion equatorial region by the Sloan Digital Sky
Survey has revealed that significant variability in the blue continuum persists
into the late-M spectral types, indicating that magnetospheric accretion
processes occur below the substellar boundary in the Orion OB1 association. We
investigate the strength of the accretion-related continuum veiling by
comparing the reddening-invariant colors of the most highly variable stars
against those of main sequence M dwarfs and evolutionary models. A gradual
decrease in the g band veiling is seen for the cooler and less massive members,
as expected for a declining accretion rate with decreasing mass. We also see
evidence that the temperature of the accretion shock decreases in the very low
mass regime, reflecting a reduction in the energy flux carried by the accretion
columns. We find that the near-IR excess attributed to circumstellar disk
thermal emission drops rapidly for spectral types later than M4. This is likely
due to the decrease in color contrast between the disk and the cooler stellar
photosphere. Since accretion, which requires a substantial stellar magnetic
field and the presence of a circumstellar disk, is inferred for masses down to
0.05 Msol we surmise that brown dwarfs and low mass stars share a common mode
of formation.Comment: 37 pages, 14 figures, accepted by A
Influence of Precipitation and Crop Germination on Resource Selection by Mule Deer (\u3ci\u3eOdocoileus hemionus\u3c/i\u3e) in Southwest Colorado
Mule deer (Odocoileus hemionus) populations in the western United States provide many benefits to local economies but can also cause considerable damage to agriculture, particularly damage to lucrative crops. Limited information exists to understand resource selection of mule deer in response to annual variation in crop rotation and climatic conditions. We tested the hypothesis that mule deer select certain crops, and in particular sunflower, based on annual climatic variability. Our objective was to use movements, estimates of home range, and resource selection analysis to identify resources selected by mule deer. We used annually-derived crop-specific datasets along with Global Positioning System collars to monitor 14 mule deer in an agricultural area near public lands in southwestern Colorado, USA. We estimated home ranges for two winter seasons that ranged between 7.68 and 9.88 km2, and for two summer seasons that ranged between 5.51 and 6.24 km2. Mule deer selected areas closer to forest and alfalfa for most periods during 2012, but selected areas closer to sunflower in a majority of periods during 2013. Considerable annual variation in climate patterns and precipitation levels appeared to influence selection by mule deer because of variability in crop rotation and success of germination of specific crops
Functional renormalization group approach to correlated fermion systems
Numerous correlated electron systems exhibit a strongly scale-dependent
behavior. Upon lowering the energy scale, collective phenomena, bound states,
and new effective degrees of freedom emerge. Typical examples include (i)
competing magnetic, charge, and pairing instabilities in two-dimensional
electron systems, (ii) the interplay of electronic excitations and order
parameter fluctuations near thermal and quantum phase transitions in metals,
(iii) correlation effects such as Luttinger liquid behavior and the Kondo
effect showing up in linear and non-equilibrium transport through quantum wires
and quantum dots. The functional renormalization group is a flexible and
unbiased tool for dealing with such scale-dependent behavior. Its starting
point is an exact functional flow equation, which yields the gradual evolution
from a microscopic model action to the final effective action as a function of
a continuously decreasing energy scale. Expanding in powers of the fields one
obtains an exact hierarchy of flow equations for vertex functions. Truncations
of this hierarchy have led to powerful new approximation schemes. This review
is a comprehensive introduction to the functional renormalization group method
for interacting Fermi systems. We present a self-contained derivation of the
exact flow equations and describe frequently used truncation schemes. Reviewing
selected applications we then show how approximations based on the functional
renormalization group can be fruitfully used to improve our understanding of
correlated fermion systems.Comment: Review article, final version, 59 pages, 28 figure
Forecasting the spread of raccoon rabies using a purpose-specific group decisionmaking process
The Centers for Disease Control (CDC) and USDA Wildlife Services (WS) have been involved in an oral rabies vaccination (ORV) program for raccoons (Procyon lotor) that has slowed the westward spread of raccoon rabies. The objective of this study was to forecast the spread of the disease if an ORV zone was not maintained. A group decision-making process was designed to address the forecasting problem and was implemented using a group of 15 experts and 4 support personnel at a meeting at the USDA National Wildlife Research Center. Ten expansion regions were constructed that described the spread of disease at 2-year intervals. This forecast may provide for more accurate cost-benefit analysis of the ORV barrier
Bosonization of interacting fermions in arbitrary dimension beyond the Gaussian approximation
We use our recently developed functional bosonization approach to bosonize
interacting fermions in arbitrary dimension beyond the Gaussian
approximation. Even in the finite curvature of the energy dispersion at
the Fermi surface gives rise to interactions between the bosons. In higher
dimensions scattering processes describing momentum transfer between different
patches on the Fermi surface (around-the-corner processes) are an additional
source for corrections to the Gaussian approximation. We derive an explicit
expression for the leading correction to the bosonized Hamiltonian and the
irreducible self-energy of the bosonic propagator that takes the finite
curvature as well as around-the-corner processes into account. In the special
case that around-the-corner scattering is negligible, we show that the
self-energy correction to the Gaussian propagator is negligible if the
dimensionless quantities are
small compared with unity for all patches . Here is the cutoff
of the interaction in wave-vector space, is the Fermi wave-vector,
is the chemical potential, is the usual dimensionless Landau
interaction-parameter, and is the {\it{local}} density of
states associated with patch . We also show that the well known
cancellation between vertex- and self-energy corrections in one-dimensional
systems, which is responsible for the fact that the random-phase approximation
for the density-density correlation function is exact in , exists also in
, provided (1) the interaction cutoff is small compared with
, and (2) the energy dispersion is locally linearized at the Fermi the
Fermi surface. Finally, we suggest a new systematic method to calculate
corrections to the RPA, which is based on the perturbative calculation of the
irreducible bosonic self-energy arising from the non-Gaussian terms of the
bosonized Hamiltonian.Comment: The abstract has been rewritten. No major changes in the text
Access to communication technologies in a sample of cancer patients: an urban and rural survey
BACKGROUND: There is a growing awareness among providers of the symptom burden experienced by cancer patients. Systematic symptom screening is difficult. Our plan was to evaluate a technology-based symptom screening process using touch-tone telephone and Internet in our rural outreach cancer program in Indiana. Would rural patients have adequate access to technologies for home-based symptom reporting? OBJECTIVES: 1) To determine access to touch-tone telephone service and Internet for patients in urban and rural clinics; 2) to determine barriers to access; 3) to determine willingness to use technology for home-based symptom reporting. METHODS: Patients from representative clinics (seven rural and three urban) in our network were surveyed. Inclusion criteria were age greater than 18, able to read, and diagnosis of malignancy. RESULTS: The response rate was 97%. Of 416 patients completing the survey (230 rural, 186 urban), 95% had access to touch-tone telephone service, while 46% had Internet access (56% of urban patients, 38% of rural patients). Higher rates of Internet access were related to younger patient age, current employment, and higher education and income. The primary barrier to Internet access was lack of interest. Use of the Internet for health related activities was less than 50%. The preferred means of symptom reporting in patients with internet access were the touch-tone telephone (70%), compared to reporting by the Internet (28%). CONCLUSION: Access to communication technologies appears adequate for home-based symptom reporting. The use of touch-tone telephone and Internet reporting, based upon patient preference, has the potential of enhancing symptom detection among cancer patients that is not dependent solely upon clinic visits and clinician inquiry
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