AGRICULTURAL LAND VALUES AND FUTURE LAND DEVELOPMENT

We develop a theoretical model of land prices and urban expansion and derive a reduced-form expression for agricultural land values. This result dictates the specification of our econometric model in terms of variable choice and functional form. We find strong support for the model in an application to New York.Land Economics/Use,

Characterizing runoff responses in a mountaintop mine impacted and forested catchment in the coalfields of West Virginia

Mountaintop mining (MTM) represents the largest land cover/landuse change in the Central Appalachian region. By 2012, the U.S. EPA estimates that MTR will have impacted approximately 6.8% of the predominately forested Appalachian Coalfield region of West Virginia (WV), Kentucky, Tennessee, and Virginia with nearly 4,000 miles of headwater streams buried under valley fills (VF). In spite of the scale and extent of MTM, its hydrologic impacts are poorly understood. Several devastating floods in the region have been attributed to MTM, but there is little evidence to either confirm or refute this belief. Existing research on the hydrologic impacts of MTM has documented a range of potential impacts to the storm hydrograph and seasonal flow regimes but has also revealed considerable variability in hydrologic responses to differing storm events, extents of disturbance, and stage of reclamation. Additional uncertainty stems from our poor understanding runoff processes of forested catchments in the southern coalfields of West Virginia. This study begins to address this knowledge gap by exploring rainfall-runoff relationships in two headwater catchments in southern West Virginia: a predominantly forested catchment with no active surface mining and another undergoing active MTM and VF that disturbs 20% of its catchment area. Streamflow (Q) and precipitation (P) were measured in each catchment from 01 September 2011 to 30 September 2012 and 23 discrete storm events were selected for analysis. Both catchments responded rapidly to precipitation inputs but the MTM-impacted catchment experienced significantly greater total runoff (3x), higher peak runoff (2x), greater runoff ratios (Q/P) (2x), greater baseflows, and shorter time lags from peak precipitation to peak runoff (2x). Hydraulic response time, a fundamental hydraulic parameter that controls the conversion of rainfall to runoff, was modeled with a transfer function rainfall-runoff model and found to be more rapid in the MTM-impacted catchment. The source of these differences is likely attributable to some combination of three factors: surface disturbance of MTM/VF operations, the smaller drainage area of the MTM-impacted catchment and additional water inputs from legacy underground mining in the MTM-impacted catchment. Results from this study reflect the hydrologic complexity of runoff generation the southern coalfields of West Virginia. Future research efforts should quantify the physical processes that control hydrologic response in these heavily disturbed landscapes

A Proposed Amendment to Rule 26(b)(4)(B): The Expert Twice Retained

This article will focus on whether the hiring of the free agent as a non-trial expert, in order to conceal information from other parties to the litigation, is in keeping with the underlying goals and values of present discovery practice. Part I of this note discusses the discoverability of experts in general, then examines the various rationales underlying the so-called unfairness doctrine supporting the trial/non-trial expert distinction. Part II presents the case for divergent treatment of the free agent and the regularly retained expert. Subpart A of that section will explain the lack of judicial scrutiny in this area, while Subpart B will explore the application of the present trial/non-trial expert discovery distinction to the free agent expert. The analysis in Part II concludes that the existing discovery rules should be modified to discourage the hiring of experts to conceal information. This modification of present discovery is suggested in Part III as an amendment to Rule 26, which presently governs the discovery of experts. Both the analysis of and the proposed amendment to the Federal Rule are equally applicable to many state discovery rules

The October 27-28, 1986, FIRE cirrus case study: Cloud microstructure

Using aircraft in-situ measurements, the microphysics of cirrus clouds observed on 28 Oct. 1986 during FIRE were examined. Results are presented as one component of a coordinated study of the cirrus on the day. The study contributes to the understanding of cold clouds by: (1) providing microphysical data to supplement satellite and aircraft data for investigating cirrus cloud radiative effects; (2) providing more complete information on ice particle evolution and cloud forcing mechanisms than has been available through the use of instrumentation with higher resolution and more accurate calibration; (3) expanding the knowledge of the particle characteristics in cold liquid water clouds, through improved instrumentation and by making use of sensors on other platforms, such as lidar; and (4) by estimating the ice nucleus concentrations active at low temperatures in the upper troposphere from the concentrations of ice particles in colloidally stable liquid water clouds

Reducing Reparameterization Gradient Variance

Optimization with noisy gradients has become ubiquitous in statistics and machine learning. Reparameterization gradients, or gradient estimates computed via the "reparameterization trick," represent a class of noisy gradients often used in Monte Carlo variational inference (MCVI). However, when these gradient estimators are too noisy, the optimization procedure can be slow or fail to converge. One way to reduce noise is to use more samples for the gradient estimate, but this can be computationally expensive. Instead, we view the noisy gradient as a random variable, and form an inexpensive approximation of the generating procedure for the gradient sample. This approximation has high correlation with the noisy gradient by construction, making it a useful control variate for variance reduction. We demonstrate our approach on non-conjugate multi-level hierarchical models and a Bayesian neural net where we observed gradient variance reductions of multiple orders of magnitude (20-2,000x)

Characterization of IM7/8552 Thin-Ply and Hybrid Thin-Ply Composites

Composite materials have increasingly been used for aerospace applications due to improved performance and reduced weight compared to their metallic counterparts. Inclusion of thin-ply material, plies with cured thickness half or less than standard composites, have potential to improve performance and reduce structural weight. Limited characterization of thin-ply IM7/8552 material in 30 and 70 grams per square meter fiber areal weights has been carried out using a series of selected American Society for Testing and Materials (ASTM) tests. Tests included unnotched tension, unnotched compression, v-notched rail shear, open-hole tension, and open-hole compression. Unidirectional, cross-ply, quasiisotropic and hybrid hard laminates were included in the study, and were compared to standard-ply laminates. Properties compared include fiber volume, laminate moduli, and failure strength, with failure modes also being examined. The thin-ply specimens exhibited similar or superior performance to standard ply laminates in many of the cases compared. Improvements in strength for laminates containing thin-ply material were seen for unidirectional laminates under unnotched tension, quasi-isotropic laminates under unnotched tension and compression, and hard laminates under open hole tension. Additional investigation is required to determine appropriate ply stacking rules for hybrids of thin and standard plies to avoid undesirable failure modes such as axial splitting. However, the observed performance improvements demonstrated by the conducted ASTM tests of hybrid thin-ply hard laminates could have benefits for improved structural weight in aircraft

The emergence of 4-cycles in polynomial maps over the extended integers

Let $f(x) \in \mathbb{Z}[x]$; for each integer $\alpha$ it is interesting to consider the number of iterates $n_{\alpha}$, if possible, needed to satisfy $f^{n_{\alpha}}(\alpha) = \alpha$. The sets $\{\alpha, f(\alpha), \ldots, f^{n_{\alpha} - 1}(\alpha), \alpha\}$ generated by the iterates of $f$ are called cycles. For $\mathbb{Z}[x]$ it is known that cycles of length 1 and 2 occur, and no others. While much is known for extensions to number fields, we concentrate on extending $\mathbb{Z}$ by adjoining reciprocals of primes. Let $\mathbb{Z}[1/p_1, \ldots, 1/p_n]$ denote $\mathbb{Z}$ extended by adding in the reciprocals of the $n$ primes $p_1, \ldots, p_n$ and all their products and powers with each other and the elements of $\mathbb{Z}$. Interestingly, cycles of length 4, called 4-cycles, emerge for polynomials in $\mathbb{Z}\left[1/p_1, \ldots, 1/p_n\right][x]$ under the appropriate conditions. The problem of finding criteria under which 4-cycles emerge is equivalent to determining how often a sum of four terms is zero, where the terms are $\pm 1$ times a product of elements from the list of $n$ primes. We investigate conditions on sets of primes under which 4-cycles emerge. We characterize when 4-cycles emerge if the set has one or two primes, and (assuming a generalization of the ABC conjecture) find conditions on sets of primes guaranteed not to cause 4-cycles to emerge.Comment: 14 pages, 1 figur