TRANSACTION CHAIN APPROACH TO THE REGULATION OF THE NONPOINT WATER POLLUTION FROM FARMS-RUNOFF

We offer a decentralized solution to the asymmetric information and hidden action problems in the nonpoint source (NPS) pollution case. Farmers in the same watershed generate homogeneous NPS pollution. The regulator, R, pays for (or represents a group of point-source, PS, polluters who pay for) pollution reduction credits earned by the group of the farmers. To resolve the asymmetric information problem, R is concerned with only the total level of the abatement achieved, while the group of farmers (called the Association, A), undertakes responsibility to distribute the payment so as to induce farmers to deliver abatement. We show that A can devise an optimal contract to deal with the farmers' hidden action problem. We identify the restrictions under which such a policy can be implemented, evaluate its effects on the product market, and show that in the NPS case information rents are higher than in the PS case.Environmental Economics and Policy,

Essays on environmental issues associated with the diary production region in Louisiana

The Louisiana dairy production region (LDPR) is located in southeast Louisiana and includes five parishes (Tangipahoa, Washington, Livingston, St. Helena, and St. Tammany). It is home to approximately 90% of the state’s dairy industry and is a major contributor to nonpoint source pollution (NPS) in the area’s watershed through nitrogen, phosphorus, and sediment effluents. While point source (PS) effluents are easily identified and subject to federal and state regulations, NPS mitigation efforts must address uncertainties such as location of the NPS as well as stochastic parameters such as rainfall and its effect on nutrient and sediment flow. This dissertation presents three strategies to mitigate the effects of the NPS pollution. The first strategy is to identify dairy specific Best Management Practices (BMPs) that best mitigate NPS at the lowest cost. Using geographical information system (GIS) software to simulate nutrient (Nitrogen and Phosphorus) runoff and sediment flow, a suite of seven BMPs are identified that lead to high N reduction with a minimal cost solution. The second strategy uses point source PS/NPS trading to achieve mitigation. A section of the LDPR is identified containing approximately 162 dairy farmers, six point sources, and two weather stations. Using a trading ratio to capture uncertainty inherent with NPS pollution, trading ratios are identified for a range of values for both BMP efficacy and reliability of NPS variance estimates. The less assurance the researcher has in the validity of these parameters, the higher the trading ratio and the more effluent credits the PS will be required to purchase for the NPS in lieu of further PS abatement. The final strategy uses the Hazard model to identify entry and exit BMP adoption characteristics of dairy farmers. The effectiveness of NPS mitigation was found to increase if a BMP is adopted for a longer duration. Research concludes that higher level of education of the farmer and the longer that the dairy farmer has been in operation, the longer the adoption of the BMP

Numerical investigation of the effect of crosswind on sound propagation outdoors

The effect of wind on sound propagation in the atmosphere has been studied extensively before with an emphasize on downwind sound propagation, typically representing worst-case scenarios. However, the influence of oblique and crosswind on propagation from various types of sources raises some questions in acoustic literature. In this work, the effect of a logarithmic wind speed profile at different wind directions has been studied for sound emitted by a point source, a coherent line source and an incoherent line source. For this purpose, a full three-dimensional wave-based method was used. For the incoherent line source simulation, the Harmonoise engineering approach based on a summation of source segments was considered as well and shows to be in satisfying agreement with the latter. While for a point source and coherent line source crosswind shows to have an insignificant effect, it is important in case of an incoherent line source. Also, the stretch of the incoherent line source contributing to the noise level at a receiver close to this line differs strongly depending on the wind direction

Fermi Large Area Telescope observations of the Vela-X Pulsar Wind Nebula

We report on gamma-ray observations in the off-pulse window of the Vela pulsar PSR B0833-45, using 11 months of survey data from the Fermi Large Area Telescope (LAT). This pulsar is located in the 8 degree diameter Vela supernova remnant, which contains several regions of non-thermal emission detected in the radio, X-ray and gamma-ray bands. The gamma-ray emission detected by the LAT lies within one of these regions, the 2*3 degrees area south of the pulsar known as Vela-X. The LAT flux is signicantly spatially extended with a best-fit radius of 0.88 +/- 0.12 degrees for an assumed radially symmetric uniform disk. The 200 MeV to 20 GeV LAT spectrum of this source is well described by a power-law with a spectral index of 2.41 +/- 0.09 +/- 0.15 and integral flux above 100 MeV of (4.73 +/- 0.63 +/- 1.32) * 10^{-7} cm^{-2} s^{-1}. The first errors represent the statistical error on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses give strong constraints on the energetics and magnetic field of the pulsar wind nebula (PWN) system and favor a scenario with two distinct electron populations.Comment: 21 pages, 5 figures, accepted for publication in Astrophysical Journa

Non-destructive imaging of an individual protein

The mode of action of proteins is to a large extent given by their ability to adopt different conformations. This is why imaging single biomolecules at atomic resolution is one of the ultimate goals of biophysics and structural biology. The existing protein database has emerged from X-ray crystallography, NMR or cryo-TEM investigations. However, these tools all require averaging over a large number of proteins and thus over different conformations. This of course results in the loss of structural information. Likewise it has been shown that even the emergent X-FEL technique will not get away without averaging over a large quantity of molecules. Here we report the first recordings of a protein at sub-nanometer resolution obtained from one individual ferritin by means of low-energy electron holography. One single protein could be imaged for an extended period of time without any sign of radiation damage. Since ferritin exhibits an iron core, the holographic reconstructions could also be cross-validated against TEM images of the very same molecule by imaging the iron cluster inside the molecule while the protein shell is decomposed

Topological Insulators by Topology Optimization

An acoustic topological insulator (TI) is synthesized using topology optimization, a free material inverse design method. The TI appears spontaneously from the optimization process without imposing requirements on the existence of pseudo spin-1/2 states at the TI interface edge, or the Chern number of the topological phases. The resulting TI is passive; consisting of acoustically hard members placed in an air background and has an operational bandwidth of $\approx$12.5\% showing high transmission. Further analysis demonstrates confinement of more than 99\% of the total field intensity in the TI within at most six lattice constants from the TI interface. The proposed design hereby outperforms a reference from recent literature regarding energy transmission, field confinement and operational bandwidth.Comment: 6 pages, 5 figure

Cold DUst around NEarby Stars (DUNES). First results: A resolved exo-Kuiper belt around the solar-like star ζ^2 Ret

We present the first far-IR observations of the solar-type stars δ Pav, HR 8501, 51 Peg and ζ^2 Ret, taken within the context of the DUNES Herschel open time key programme (OTKP). This project uses the PACS and SPIRE instruments with the objective of studying infrared excesses due to exo-Kuiper belts around nearby solar-type stars. The observed 100 μm fluxes from δ Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes, excluding debris disks brighter than L_(dust)/L_* ~ 5 × 10^(-7) (1σ level) around those stars. A flattened, disk-like structure with a semi-major axis of ~100 AU in size is detected around ζ^2 Ret. The resolved structure suggests the presence of an eccentric dust ring, which we interpret as an exo-Kuiper belt with L_(dust)/L_* ≈ 10^(-5)