12,805 research outputs found

    FARM-LEVEL RESPONSE TO AGRICULTURAL EFFLUENT CONTROL STRATEGIES: THE CASE OF THE WILLAMETTE VALLEY

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    This article examines economic incentives and other mechanisms to offset non-point source pollution from agriculture. A biophysical simulator to estimate technical relationships is linked to linear programming models for representative farms in the Willamette Valley of Oregon. The models are then optimized for profit maximization under alternative non-point pollution control policies. The results indicate that site-specific resource conditions and production possibilities greatly influence policy effectiveness and the cost of achieving pollution abatement. Nevertheless, some abatement is possible on all farms for relatively little cost.Environmental Economics and Policy,

    Quantum phase transition in spin glasses with multi-spin interactions

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    We examine the phase diagram of the pp-interaction spin glass model in a transverse field. We consider a spherical version of the model and compare with results obtained in the Ising case. The analysis of the spherical model, with and without quantization, reveals a phase diagram very similar to that obtained in the Ising case. In particular, using the static approximation, reentrance is observed at low temperatures in both the quantum spherical and Ising models. This is an artifact of the approximation and disappears when the imaginary time dependence of the order parameter is taken into account. The resulting phase diagram is checked by accurate numerical investigation of the phase boundaries.Comment: 20 Pages including 10 figures, Revte

    Lack of Transit Timing Variations of OGLE-TR-111b: A re-analysis with six new epochs

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    We present six new transits of the exoplanet OGLE-TR-111b observed with the Magellan Telescopes in Chile between April 2008 and March 2009. We combine these new transits with five previously published transit epochs for this planet between 2005 and 2006 to extend the analysis of transit timing variations reported for this system. We derive a new planetary radius value of 1.019 +/- 0.026 R_J, which is intermediate to the previously reported radii of 1.067 +/- 0.054 R_J (Winn et al. 2007) and 0.922 +/- 0.057 R_J (Diaz et al. 2008). We also examine the transit timing variation and duration change claims of Diaz et al. (2008). Our analysis of all eleven transit epochs does not reveal any points with deviations larger than 2 sigma, and most points are well within 1 sigma. Although the transit duration nominally decreases over the four year span of the data, systematic errors in the photometry can account for this result. Therefore, there is no compelling evidence for either a timing or a duration variation in this system. Numerical integrations place an upper limit of about 1 M_E on the mass of a potential second planet in a 2:1 mean-motion resonance with OGLE-TR-111b.Comment: 28 pages, 7 tables, 6 figures. Accepted by Ap

    Training Extension Professionals from Developing Countries Through Educational Workshops Conducted in the United States

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    Many opportunities exist for conducting stateside professional improvement workshops to train Extension professionals from developing countries. To conduct a successful workshop it is important to understand the needs of the partner country and identify participants who can use their workshop training to address those needs. An effective workshop will have high-quality field trips, practical classroom instruction, and opportunities for cultural exchange. Pre-workshop planning and close attention to logistical issues are essential to the success of the workshop. Good evaluation of the workshop is important to measure the impacts of the workshop and provide input for improving future workshops

    Mechanisms of Mental-Health Disparities Among Minoritized Groups: How Well Are the Top Journals in Clinical Psychology Representing This Work?

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    It has been known for decades that mental-health disparities exist among minoritized groups, including race, ethnicity, sexual identities, gender identity and expression, ability, and others. Theories and frameworks that incorporate stressors unique to the experiences of minoritized groups, such as the biopsychosocial model of racism and minority-stress model, offer testable mechanisms that may help explain, in part, mental-health disparities. However, research addressing mechanisms of these disparities is still scarce and is not well represented in top clinical psychology journals. In this review, we critically examine the extent to which top-tier clinical psychology journals publish work examining mechanisms of mental-health disparities among minoritized populations. We found that very few studies that address mechanisms of mental-health disparities have been published in top clinical psychology journals. We examine potential reasons for this and discuss recommendations for future research

    Nucleon Charge Symmetry Breaking and Parity Violating Electron-Proton Scattering

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    The consequences of the charge symmetry breaking effects of the mass difference between the up and down quarks and electromagnetic effects for searches for strangeness form factors in parity violating electron scattering from the proton are investigated. The formalism necessary to identify and compute the relevant observables is developed by separating the Hamiltonian into charge symmetry conserving and breaking terms. Using a set of SU(6) non-relativistic quark models, the effects of the charge symmetry breaking Hamiltonian are considered for experimentally relevant alues of the momentum transfer and found to be less than about 1 percent. The charge symmetry breaking corrections to the Bjorken sum rule are also studied and shown to vanish in first-order perturbation theory.Comment: 35 pages, 9 figure

    Applicability of Monte Carlo Glauber models to relativistic heavy ion collision data

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    The accuracy of Monte Carlo Glauber model descriptions of minimum-bias multiplicity frequency distributions is evaluated using data from the Relativistic Heavy Ion Collider (RHIC) within the context of a sensitive, power-law representation introduced previously by Trainor and Prindle (TP). Uncertainties in the Glauber model input and in the mid-rapidity multiplicity frequency distribution data are reviewed and estimated using the TP centrality methodology. The resulting errors in model-dependent geometrical quantities used to characterize heavy ion collisions ({\em i.e.} impact parameter, number of nucleon participants NpartN_{part}, number of binary interactions NbinN_{bin}, and average number of binary collisions per incident participant nucleon ν\nu) are presented for minimum-bias Au-Au collisions at sNN\sqrt{s_{NN}} = 20, 62, 130 and 200 GeV and Cu-Cu collisions at sNN\sqrt{s_{NN}} = 62 and 200 GeV. Considerable improvement in the accuracy of collision geometry quantities is obtained compared to previous Monte Carlo Glauber model studies, confirming the TP conclusions. The present analysis provides a comprehensive list of the sources of uncertainty and the resulting errors in the above geometrical collision quantities as functions of centrality. The capability of energy deposition data from trigger detectors to enable further improvements in the accuracy of collision geometry quantities is also discussed.Comment: 27 pages, 4 figures, 11 table

    Cross Section Measurements Using the Zero Degree Detector

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    The Zero Degree Detector (ZDD) is an instrument that has been used in accelerator exposures to measure the angular dependence of particles produced in heavy ion fragmentation experiments. The ZDD uses two identical layers of pixelated silicon detectors that make coincident measurements over the active area of the instrument. The angular distribution of secondary particle produced in nuclear interactions for several heavy ions: and target materials will be presented along with performance characteristic of the instrument

    Blackbody-radiation-assisted molecular laser cooling

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    The translational motion of molecular ions can be effectively cooled sympathetically to temperatures below 100 mK in ion traps through Coulomb interactions with laser-cooled atomic ions. The distribution of internal rovibrational states, however, gets in thermal equilibrium with the typically much higher temperature of the environment within tens of seconds. We consider a concept for rotational cooling of such internally hot, but translationally cold heteronuclear diatomic molecular ions. The scheme relies on a combination of optical pumping from a few specific rotational levels into a ``dark state'' with redistribution of rotational populations mediated by blackbody radiation.Comment: 4 pages, 5 figure
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