Working-Land Conservation Structures: Evidence on Program and Non-Program Participants

In recent years, the Federal government has placed more emphasis on working-land conservation programs. Farmers can be reimbursed for adopting certain conservation practices, such as the installation of in-field or perimeter conservation structures, to enhance water quality and soil productivity. In an effort to better understand the relationships between operator motivations, program incentives, and the environmental benefits of conservation programs, a multi-agency survey, the Conservation Effects Assessment Project-Agricultural Resources Management Survey (CEAP-ARMS), was conducted in 2004 across 16 states representing more than one-million farmers growing wheat. The nationally representative survey integrates Natural Resources Inventory (NRI) data on field-level physical characteristics, program information, farm-level costs of production, and farm household information. This objective of this paper is twofold. First, using the CEAP-ARMS, farm structure, household, and operator characteristics of farmers participating in one or more conservation programs are compared with farmers not participating in a conservation program. Second, an impact model is specified to test whether program participants allocated more acres to in-field or perimeter conservation structures than nonparticipants, holding other factors constant. Evidence suggests that program participants allocate more field acres to vegetative conservation structures than nonparticipants with in-field or perimeter conservation structures.Environmental Economics and Policy,

Geographical Analysis of US Green Sector Industry Concentration

This paper analyzes the geographic distribution of “green energy” sector clustering in the lower 48 United States using recent developments in industry concentration analysis. Evidence suggests that the ten green energy subsectors and the aggregate of the firms comprising the green energy sector are regionally concentrated. Positive changes in industry concentration from 2002 to 2006 tended to be greatest in non-metropolitan counties, suggesting comparative advantage with respect to site location for the composite of firms making up these sectors.Agglomeration, Location Quotient, Renewable Energy, Community/Rural/Urban Development, Industrial Organization, Research and Development/Tech Change/Emerging Technologies,

R&D Needs for Integrated Biorefineries: The 30x30 Vision

Presentation on progress and possible scenarios towards meeting the 30x30 initiative proposed by President Bus

A Comparison of Network Sampling Designs for a Hidden Population of Drug Users: Random Walk vs. Respondent-Driven Sampling

Both random walk and respondent-driven sampling (RDS) exploit social networks and may reduce biases introduced by earlier methods for sampling from hidden populations. Although RDS has become much more widely used by social researchers than random walk (RW), there has been little discussion of the tradeoffs in choosing RDS over RW. This paper compares experiences of implementing RW and RDS to recruit drug users to a network-based study in Houston, Texas. Both recruitment methods were implemented over comparable periods of time, with the same population, by the same research staff. RDS methods recruited more participants with less strain on staff. However, participants recruited through RW were more forthcoming than RDS participants in helping to recruit members of their social networks. Findings indicate that, dependent upon study goals, researchers' choice of design may influence participant recruitment, participant commitment, and impact on staff, factors that may in turn affect overall study success

Ex Vivo Porcine Arterial and Chorioallantoic Membrane Acoustic Angiography Using Dual-Frequency Intravascular Ultrasound Probes

The presence of blood vessels within a developing atherosclerotic plaque has been shown to be correlated to increased plaque vulnerability and ensuing cardiac events, however, detecting coronary intraplaque neovascularizations poses a significant challenge in the clinic. In this paper, we demonstrate in vivo a new intravascular ultrasound imaging method using a dual-frequency transducer to visualize contrast flow in microvessels with high specificity. This method uses a specialized transducer capable of exciting contrast agents at a low frequency (5.5 MHz) while detecting their nonlinear superhamonics at a much higher frequency (37 MHz). In vitro evaluation of the approach was performed in a microvascular phantom to produce 3D renderings of simulated vessel patterns and to determine image quality metrics as a function of depth. Furthermore, the ability of the system to detect microvessels is demonstrated both ex vivo using porcine arteries and in vivo using the chorioallantoic membrane of a developing chicken embryo with optical confirmation. Dual-frequency contrast specific imaging was able to resolve vessels of a similar size to those found in vulnerable atherosclerotic plaques at clinically relevant depths. The results of this study adds growing support for further evaluation and translation of contrast specific imaging in intravascular ultrasound for the detection of vulnerable plaques in atherosclerosis

Ultrasound Molecular Imaging of VEGFR-2 in Clear-Cell Renal Cell Carcinoma Tracks Disease Response to Antiangiogenic and Notch-Inhibition Therapy

Metastatic clear-cell renal cell carcinoma (ccRCC) affects thousands of patients worldwide each year. Antiangiogenic therapy has been shown to have beneficial effects initially, but resistance is eventually developed. Therefore, it is important to accurately track the response of cancer to different therapeutics in order to appropriately adjust the therapy to maximize efficacy. Change in tumor volume is the current gold standard for determining efficacy of treatment. However, functional variations can occur much earlier than measurable volume changes. Contrast-enhanced ultrasound (CEUS) is an important tool for assessing tumor progression and response to therapy, since it can monitor functional changes in the physiology. In this study, we demonstrate how ultrasound molecular imaging (USMI) can accurately track the evolution of the disease and molecular response to treatment

Modern optical astronomy: technology and impact of interferometry

The present `state of the art' and the path to future progress in high spatial resolution imaging interferometry is reviewed. The review begins with a treatment of the fundamentals of stellar optical interferometry, the origin, properties, optical effects of turbulence in the Earth's atmosphere, the passive methods that are applied on a single telescope to overcome atmospheric image degradation such as speckle interferometry, and various other techniques. These topics include differential speckle interferometry, speckle spectroscopy and polarimetry, phase diversity, wavefront shearing interferometry, phase-closure methods, dark speckle imaging, as well as the limitations imposed by the detectors on the performance of speckle imaging. A brief account is given of the technological innovation of adaptive-optics (AO) to compensate such atmospheric effects on the image in real time. A major advancement involves the transition from single-aperture to the dilute-aperture interferometry using multiple telescopes. Therefore, the review deals with recent developments involving ground-based, and space-based optical arrays. Emphasis is placed on the problems specific to delay-lines, beam recombination, polarization, dispersion, fringe-tracking, bootstrapping, coherencing and cophasing, and recovery of the visibility functions. The role of AO in enhancing visibilities is also discussed. The applications of interferometry, such as imaging, astrometry, and nulling are described. The mathematical intricacies of the various `post-detection' image-processing techniques are examined critically. The review concludes with a discussion of the astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics, 2002, to appear in April issu