Studies of the scattering/absorption of minerals

Reflectance spectra were computed for water ice and ammonia ice mixtures as functions of weight fraction, grain size, and viewing geometry to simulate possible outer solar system satellite surfaces. Reflectance spectra of planetary surfaces are most affected by the weight fraction and grain sizes of the minerals in the surface. The reflectance can range from 1.0 to about 0.01 by changing the grain size or weight fraction, a factor of 100. Viewing geometry changes the reflectance by about 25 percent or less

Tax Aversion, Deficits and the Tax Rate-Tax Revenue Relationship

This paper offers a possible explanation for the existence of continual government budget deficits such as experienced in a number of industrialized countries in recent years. Based on the assumption that higher tax rates cause more intensive tax-aversion behavior (tax avoidance and tax evasion), together with the assumption that the time horizon relevant for political decision makers is shorter than that required for complete private sector response to tax rate change, our analysis suggests why there seems to be an inherent bias toward budget deficits. Because of tax aversion an inverse relationship between tax rates and tax revenues may exist at low levels of the tax rate. Consequently determined attempts to eliminate or reduce deficits can become self-defeating, almost certainly so when there is a structural deficit. Our analysis suggests that if an economy is on the downward sloping portion of a stylized Laffer curve political expedience, uncertainty about the shape of the curve, and a common wisdom that tax rate increases reduce deficits can all conspire to keep the budget trapped in deficit. Finally, in the presence of inflation deficit growth may be less if there is indexation of income tax rates to inflation, contrary to conventional wisdom.

Tax Aversion, Optimal Tax Rates, and Indexation

Taking account of the costs of tax evasion and avoidance activity together with the government's costs of tax enforcement it is shown that the optimal point on a stylized Laffer curve is located on the positively sloped region, not at the maximum point of the, curve. The analysis eschews the usual supply-side-type rationale for the Laffer curve and shows that such a curve can arise solely as a consequence of the optimizing tax aversion activity of a utility maximizing economic agent. The analysis further implies that indexation to inflation may be warranted by considerations of economic efficiency.

LEO high voltage solar array arcing response model

A series of mathematical models were developed that describe the electrical behavior of a large solar cell array floating electrically in the low Earth orbit (LEO) space plasma and struck by an arc at a point of negative bias. There are now three models in this series: ARCII, which is a fully analytical, linearized model; ARCIII, which is an extension of ARCIII that includes solar cell inductance as well as load reactance; Nonlinear ARC, which is a numerical model able to treat effects such as non-linearized, i.e., logarithmic solar cell I/V characteristics, conductance switching as a solar cell crosses plasma ground on a voltage excursion and non-ohmic plasma leakage current collection

The design and development of a constant-speed solar array drive

The design and development of a constant-speed solar array drive system for use in high power communications satellites is described. The relationship between continuity of motion in the solar array drive and spacecraft attitude disturbance is investigated. The selection of the system design based on the design requirements including spacecraft disturbance is discussed. The system comprises two main parts: the drive mechanism including small angle stepper motor and reduction gearing and the control electronics including ministepping drive circuits, such that a very small output step size is achieved. Factors contributing to discontinuities in motion are identified and discussed. Test methods for measurement of very small amplitudes of discontinuity at low rotational rates are described to assist in the testing of similar mechanisms

Design, Synthesis and biological evaluation of novel acridine-polyamine conjugates against prostate cancer

Prostate cancer is the most common cause of cancer death in men, aged 85 and over. Androgen receptor, a single polypeptide with three functional domains is very important during initiation and progression of the disease. In this study, a DNA intercalating agent, acridine is linked to the testosterone via a polyamine linker to obtain a compound with trifunctional characteristics, where the acridine intercalates the DNA, the polyamine linker binds the phosphoryl groups of the DNA backbone and the testosterone moiety binds into the AR ligand binding domain, with which its DNA binding domain is bound already to the DNA. This trifunctional compound and related derivatives have been synthesized and tested against androgen dependent- and androgen independent- prostate cancer cell lines and they have demonstrated to be cytotoxic at the micromolar concentrations

Moderate Asphericity of the SN 2002ic Circumstellar Envelope

The polarization of SN 2002ic interacting with a dense circumstellar envelope is calculated in the context of the asymmetric version of a previously proposed spherical interaction model. The circumstellar envelope is taken to be oblate. The observed polarization (Wang et al. 2004) can be reproduced for an aspect ratio of 0.65-0.7 assuming inclination angles >60 degrees. This model predicts a weak sensitivity of the line profiles to the orientation, in agreement with the absence of significant variations of the line profiles among SN 2002ic-like supernovae. We propose a test for distinguishing between the binary and single star progenitor scenarios based upon the polarization distribution function for the growing sample of these events.Comment: 13 pages, 4 figs., ApJ, accepte

On a problem in eigenvalue perturbation theory

We consider additive perturbations of the type $K_t=K_0+tW$, $t\in [0,1]$, where $K_0$ and $W$ are self-adjoint operators in a separable Hilbert space $\mathcal{H}$ and $W$ is bounded. In addition, we assume that the range of $W$ is a generating (i.e., cyclic) subspace for $K_0$. If $\lambda_0$ is an eigenvalue of $K_0$, then under the additional assumption that $W$ is nonnegative, the Lebesgue measure of the set of all $t\in [0,1]$ for which $\lambda_0$ is an eigenvalue of $K_t$ is known to be zero. We recall this result with its proof and show by explicit counterexample that the nonnegativity assumption $W\geq 0$ cannot be removed.Comment: 10 pages; added Lemma 2.4, typos removed; to appear in J. Math. Anal. App

On the Optimality of Reserve Requirements

An implicit rationale for a bank reserve requirement is that a central monetary authority is in a unique position (as "social planner) to impose a "socially superior" outcome to that yielded by a free banking system. We illustrate how this can be true in the context of a simple economy modeled to mimic certain basic characteristics of a monetary economy with banks and agents who trade with one another. Banks exist in our model because by pooling liquidation risks they provide liquidity otherwise unavailable to depositors, which, in turn, provides the incentive - for using deposit claims as the medium of exchange.

Consumer Preferences for Locally Produced Strawberries

Consumers were surveyed to understand preference in an effort to stabilize acreage and market share in a minor strawberry production area. Preferred attributes were identified using conjoint analysis. Local product was highest in overall relative importance, followed by price, pesticide strategy, and container. Cluster analysis identified groups with similar demographics. For two groups, local product was 77 percent and 67 percent of relative importance; for another group, price was about 75 percent of importance; while the final group was balanced across three attributes. Alignment with consumer preferences and with strategies of local retailers and wholesalers lead to suggested tactics to support local product.Crop Production/Industries, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,