Commercial Loan Underwriting and Option Valuation

This article seeks to answer why over a nineteen-year period the debt-coverage ratio for commercial noninsured properties averages 1.29. The article applies the corporate liabilities extension of the Black-Scholes option pricing model to the equity valuation of a real estate project. The regression results of the modified model robustly sustain its usefulness in explaining the derivation of the debt-coverage ratio. The results confirm that commercial mortgage loan underwriters operate with a five-year horizon in creating the equity cushion needed to protect themselves against interest-rate risk.

Surface acoustic wave solid-state rotational micromotor

Surface acoustic waves (SAWs) are used to drive a 1mm diameter rotor at speeds exceeding 9000 rpm and torque of nearly 5 nNm. Unlike recent high-speed SAW rotary motors, however, the present design does not require a fluid coupling layer but interestingly exploits adhesive stiction as an internal preload, a force usually undesirable at these scales; with additional preloads, smaller rotors can be propelled to 15 000 rpm. This solid-state motor has no moving parts except for the rotor and is sufficiently simple to allow integration into miniaturized drive systems for potential use in microfluidic diagnostics, optical switching and microrobotics

Giant Oscillations of Acoustoelectric Current in a Quantum Channel

A theory of d.c. electric current induced in a quantum channel by a propagating surface acoustic wave (acoustoelectric current) is worked out. The first observation of the acoustoelectric current in such a situation was reported by J. M. Shilton et al., Journ. Phys. C (to be published). The authors observed a very specific behavior of the acoustoelectric current in a quasi-one-dimensional channel defined in a GaAs-AlGaAs heterostructure by a split-gate depletion -- giant oscillations as a function of the gate voltage. Such a behavior was qualitatively explained by an interplay between the energy-momentum conservation law for the electrons in the upper transverse mode with a finite temperature splitting of the Fermi level. In the present paper, a more detailed theory is developed, and important limiting cases are considered.Comment: 7 pages, 2 Postscript figures, RevTeX 3.

Acoustoelectric effects in quantum constrictions

A dc current induced in a quantum constriction by a traveling acoustic wave (or by non-equilibrium ballistic phonons) is considered. We show that in many important situations the effect is originated from acoustically-induced scattering between the propagating and reflecting states in the constriction. Two particular regimes corresponding to relatively high and low acoustic frequencies are discussed. In the first regime, the acoustoelectric effect in a smooth constriction can be understood by semi-classical considerations based on local conservation laws. For the low frequency regime, we show that the acousto-conductance is closely related to the zero field conductance. The qualitative considerations are confirmed by numerical calculations both for smooth and abrupt channels.Comment: 10 pages, RevTeX, 9 postscript figures, submitted to Phys. Rev.

Identification of basepairs within Tn5 termini that are critical sfor H-NS binding to the transpososome and regulation of Tn5 transposition

<p>Abstract</p> <p>Background</p> <p>The H-NS protein is a global regulator of gene expression in bacteria and can also bind transposition complexes (transpososomes). In Tn5 transposition H-NS promotes transpososome assembly <it>in vitro </it>and disruption of the <it>hns </it>gene causes a modest decrease in Tn5 transposition (three- to five-fold). This is consistent with H-NS acting as a positive regulator of Tn5 transposition. Molecular determinants for H-NS binding to the Tn5 transpososome have not been determined, nor has the strength of the interaction been established. There is also uncertainty as to whether H-NS regulates Tn5 transposition <it>in vivo </it>through an interaction with the transposition machinery as disruption of the <it>hns </it>gene has pleiotropic effects on <it>Escherichia coli</it>, the organism used in this study.</p> <p>Results</p> <p>In the current work we have further examined determinants for H-NS binding to the Tn5 transpososome through both mutational studies on Tn5 termini (or 'transposon ends') and protein-protein cross-linking analysis. We identify mutations in two different segments of the transposon ends that abrogate H-NS binding and characterize the affinity of H-NS for wild type transposon ends in the context of the transpososome. We also show that H-NS forms cross-links with the Tn5 transposase protein specifically in the transpososome, an observation consistent with the two proteins occupying overlapping binding sites in the transposon ends. Finally, we make use of the end mutations to test the idea that H-NS exerts its impact on Tn5 transposition <it>in vivo </it>by binding directly to the transpososome. Consistent with this possibility, we show that two different end mutations reduce the sensitivity of the Tn5 system to H-NS regulation.</p> <p>Conclusions</p> <p>H-NS typically regulates cellular functions through its potent transcriptional repressor function. Work presented here provides support for an alternative mechanism of H-NS-based regulation, and adds to our understanding of how bacterial transposition can be regulated.</p

Acoustoelectric effect in a finite-length ballistic quantum channel

The dc current induced by a coherent surface acoustic wave (SAW) of wave vector q in a ballistic channel of length L is calculated. The current contains two contributions, even and odd in q. The even current exists only in a asymmetric channel, when the electron reflection coefficients r_1 and r_2 at both channel ends are different. The direction of the even current does not depend on the direction of the SAW propagation, but is reversed upon interchanging r_1 and r_2. The direction of the odd current is correlated with the direction of the SAW propagation, but is insensitive to the interchange of r_1 and r_2. It is shown that both contributions to the current are non zero only when the electron reflection coefficients at the channel ends are energy dependent. The current exhibits geometric oscillations as function of qL. These oscillations are the hallmark of the coherence of the SAW and are completely washed out when the current is induced by a flux of non-coherent phonons. The results are compared with those obtained previously by different methods and under different assumptions.Comment: 7 pages, 2 figure

Potential uses of health promotion competencies

Projects in Australia and internationally over the past two decades have sought to define and clarify competencies required to work in health promotion. It is now apparent that such competencies are very useful to health promotion practice. However, to date little attempt has been made to describe those uses.More than 200 health promotion practitioners throughout Australia were engaged in workshops to explore and define potential uses of health promotion competencies. The suggestions from these 10 workshops are summarised in eight categories of uses.Agreed health promotion competencies have potential to impact on recruitment, training, employment policy and health promotion practice

Core health promotion competencies for Australia 2007

Four hundred health promotion practitioners throughout Australian completed an on-line survey on Health Promotion Competencies for Australia at the end of 2005. This was followed by a series of workshops throughout Australia in 2006 to identify practical uses of the competencies and to determine a set of core competencies of health promotion practice in Australia. Many of the participants requested information about the results of the study. This brief report has been produced to describe the process and the final result. In addition more detailed accounts are contained in two articles that are being prepared for publication

Office Employment Growth and the Changing Function of Cities

The proportion of a city's local and regionally/nationally supported office employment changes as the city assumes more central place functions. Certain mixes of office employment should reflect the central place function of the city and promote office growth. Forty-five cities are studied using data from 1997, 1982, and 1985. The results indicate that the variance of office employment does not help predict a city's growth, but that certain cluster categories of office employment are associated with office employment growth. Finally, the results indicate that office employment profiles of cities have become more homogenized over time.