Limestone and Dolomite : Geologists and Percentage Depletion Allowances

Author Institution: Department of Geological Sciences, Virginia Polytechnic Institute, Blacksburg, Va.The Revenue Act of 1926 provided for five simple categories of natural resources to have the benefit of depletion allowances. In the 1947 Revenue Act, the number was increased to twenty-five, and in the 1951 Revenue Act to fifty-four. Of this number, fourteen were allowed 5 per cent; nine, 10 per cent; twenty-nine, 15 per cent; one, 23 per cent; and one (oil and gas), 27.5 per cent. The 1951 Revenue Act created a host of difficulties, including application of the "enduse criterion" and determination of the commonly accepted meaning of such terms as limestone, dolomite, chemical- and metallurgical-grade limestone, marble, calcium carbonates, and magnesium carbonates. Dolomite, for example, was listed at 10 per cent depletion allowance, but without definition. In the great amount of litigation growing out of the 1951 Revenue Act and its administration, it became essential to understand the derivation and subsequent usage of these common geologic terms. One thing that became clear was that our definitions changed significantly between the time that the 1951 Revenue Act became law and the time that later cases were tried. Some geologists neglected to learn about first usages of such terms as metallurgical limestone, and about meanings that were applicable when the 1951 Revenue Act was written and passed. Legal meanings in this paper are discussed in the light of certain famous cases that have been tried and settled

Singular Modes of the Electromagnetic Field

We show that the mode corresponding to the point of essential spectrum of the electromagnetic scattering operator is a vector-valued distribution representing the square root of the three-dimensional Dirac's delta function. An explicit expression for this singular mode in terms of the Weyl sequence is provided and analyzed. An essential resonance thus leads to a perfect localization (confinement) of the electromagnetic field, which in practice, however, may result in complete absorption.Comment: 14 pages, no figure

Dipolar Interactions and Origin of Spin Ice in Ising Pyrochlore Magnets

Recent experiments suggest that the Ising pyrochlore magnets ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$ display qualitative properties of the spin ice model proposed by Harris {\it et al.} \prl {\bf 79}, 2554 (1997). We discuss the dipolar energy scale present in both these materials and consider how they can display spin ice behavior {\it despite} the presence of long range interactions. Specifically, we present numerical simulations and a mean field analysis of pyrochlore Ising systems in the presence of nearest neighbor exchange and long range dipolar interactions. We find that two possible phases can occur, a long range ordered antiferromagnetic one and the other dominated by spin ice features. Our quantitative theory is in very good agreement with experimental data on both ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$. We suggest that the nearest neighbor exchange in ${\rm Dy_{2}Ti_{2}O_{7}}$ is {\it antiferromagnetic} and that spin ice behavior is induced by long range dipolar interactions.Comment: 4 postscript figures included. Submitted to Physical Review Letters Contact: [email protected]

Twisted Rindler space-times

The (linearized) noncommutative Rindler space-times associated with canonical, Lie-algebraic and quadratic twist-deformed Minkowski spaces are provided. The corresponding deformed Hawking spectra detected by Rindler observers are derived as well.Comment: 13 pages, no figures, keywords: quantum space-times, Hawking radiatio

Priorities for International Forest Research

The world is moving towards knowledge-based societies. Economies are globalizing. The global public goods value of forests is being recognised at the same time that the traditional role of state forest agencies in production forestry is being taken over by multi-national corporations. At the same time emerging technologies are greatly enhancing our ability to assess and monitor forest attributes, process and disseminate information, and enhance forest production. All of these changes will have an impact on how forest research is organized, who does it, and who pays for it. It seems inevitable that much traditional forestry research concerned with sustainability and productivity enhancement at the stand level, will be taken over by the private sector. However, there is going to be a major challenge in finding resources for research in support of the public goods values of forests at both the local, national and global levels. There is a widely held view that we are in the midst of a world forest crisis. It is not a crisis of declining production but one of erosion of public goods, environmental values of forests. So far, we have not seen a concerted scientific response to this crisis. The Inter-Governmental Panel on Forests (IPF) has given us the mandate to orchestrate such a response and the World Forestry Congress is a valuable opportunity to provide impetus to a new vision of forest science for the 21st century

Dynamic models for longitudinal butterfly data

There has been recent interest in devising stochastic models for seasonal insects, which respond rapidly to climate change. Fitted to count data, these models are used to construct indices of abundance, which guide conservation and management. We build upon Dennis et al. (2014, under review) to produce dynamic models, which provide succinct descriptions of data from all years simultaneously. They produce estimates of key life-history parameters such as annual productivity and survival. Analyses for univoltine species, with only one generation each year, extend to bivoltine species, with two annual broods. In the latter case we estimate the productivities of each generation separately, and also devise extended indices which indicate the contributions made from different generations. We demonstrate the performance of the models using count data for UK butterfly species, and compare with current procedures which use generalized additive models. We may incor- orate relevant covariates within the model, and illustrate using northing and measures of temperature. Consistent patterns are demonstrated for multiple species. This generates a variety of hypotheses for further investigation, which have the potential to illuminate features of butterfly phenology and demography which are at present poorly understood

A generalised abundance index for seasonal invertebrates

At a time of climate change and major loss of biodiversity, it is important to have efficient tools for monitoring populations. In this context, animal abundance indices play an important role. In producing indices for invertebrates, it is important to account for variation in counts within seasons. Two new methods for describing seasonal variation in invertebrate counts have recently been proposed; one is nonparametric, using generalized additive models, and the other is parametric, based on stopover models. We present a novel generalized abundance index which encompasses both parametric and nonparametric approaches. It is extremely efficient to compute this index due to the use of concentrated likelihood techniques. This has particular relevance for the analysis of data from long-term extensive monitoring schemes with records for many species and sites, for which existing modeling techniques can be prohibitively time consuming. Performance of the index is demonstrated by several applications to UK Butterfly Monitoring Scheme data. We demonstrate the potential for new insights into both phenology and spatial variation in seasonal patterns from parametric modeling and the incorporation of covariate dependence, which is relevant for both monitoring and conservation. Associated R code is available on the journal website

Improved Probability Method for Estimating Signal in the Presence of Background

A suggestion is made for improving the Feldman Cousins method of estimating signal counts in the presence of background. The method concentrates on finding essential information about the signal and ignoring extraneous information about background. An appropriate method is found which uses the condition that the number of background events obtained does not exceed the total number of events obtained. Several alternative approaches are explored.Comment: Modified 12/21 for singlespace to save trees, 9 pages, 1 figure. Modified 8/11/99 to add small modifications made for the Phys. Rev. articl

Qualification Testing of Laser Diode Pump Arrays for a Space-Based 2-micron Coherent Doppler Lidar

The 2-micron thulium and holmium-based lasers being considered as the transmitter source for space-based coherent Doppler lidar require high power laser diode pump arrays operating in a long pulse regime of about 1 msec. Operating laser diode arrays over such long pulses drastically impact their useful lifetime due to the excessive localized heating and substantial pulse-to-pulse thermal cycling of their active regions. This paper describes the long pulse performance of laser diode arrays and their critical thermal characteristics. A viable approach is then offered that allows for determining the optimum operational parameters leading to the maximum attainable lifetime