bluuebunny/crossref_metadata_2025 huggingface dataset:
Housing‐Market Segmentation and Demand for Housing Attributes: Some Empirical Findings
Authors: Bajic Vladimir
Published: October 2003

In this paper, we have empirically estimated demand equations for housing attributes, using a two‐step approach in conformity with the procedure proposed by Sherwin Rosen. The identification problem inherent in Rosen's procedure has been avoided by estimating separate equations for distinct market segments in the first step. The estimates of the demand functions obtained in the second step are consistent with theoretical expectations.
Contracts as Options: Some Evidence from Condominium Developments
Authors: Shilling James D. , Benjamin John D. , Sirmans C. F.
Published: October 2003

This paper values the real estate option to purchase contract in a contingent claims framework. The model is an application of the Black and Scholes option pricing model. Observed market data on the sale of condominiums are used to test if the option is competitively priced under various assumptions regarding the expected instantaneous variance of the condominium price. Simulation results suggest that standard industry practices of charging a fixed amount for the option to purchase roughly conform to pricing behavior dictated by the option pricing model.
Pricing Life‐of‐Loan Rate Caps on Default‐Free Adjustable‐Rate Mortgages
Authors: Buser Stephen A. , Hendershott Patric H. , Sanders Anthony B.
Published: October 2003

A model is developed and utilized in this paper to value a life‐of‐loan interest‐rate cap on an ARM that reprices monthly. The value of the cap is seen to depend importantly on both the slope of the term structure and the variance of the 1‐month rate. However, the cap value is not sensitive to the source of the slope of the term structure — what precise combination of interest‐rate expectations and risk aversion determined the slope. This insensitivity is fortunate because of the great difficulty of knowing at any point in time why the term structure is what it is.

Given the variation in the slope of the term structure and the variance of the 1‐month rate that occurred over the 1979–84 period, the addition to the coupon rate on a 1‐month ARM that lenders should have charged for a 5% life‐of‐loan cap has ranged from 5 to 40 basis points.
FHA Terminations: A Prelude to Rational Mortgage Pricing
Authors: Foster Chester , Van Order Robert
Published: October 2003

Recent models of pricing mortgages and/or mortgage insurance have used option‐pricing models as their framework. The focus is usually on default, which is viewed as a put option (to sell the house to the lender in exchange for the mortgage) and prepayment, which is viewed as a call option (to buy the mortgage from the lender). Analysis then uses techniques like those used to price options in capital markets. Unfortunately, homeowners do not seem to exercise their option as quickly as do traders in organized markets. We estimate prepayment and default functions, which are meant to be a first step in developing modified, option‐based models of mortgage pricing.
Factors Influencing the Value of Urban Land: Evidence from Halifax‐Dartmouth, Canada
Authors: Asabere Paul K. , Harvey Barrie
Published: October 2003

This study is a hedonic analysis of land values for Halifax‐Dartmouth, Canada. The study has demonstrated that conventional, well‐known urban explanatory variables such as zoning, lot size, centrality, neighborhood, and so on, found to determine values in the United States also work for a typical Canadian land market. The findings on effects of lot shape, and high traffic (in combination with other than single‐family residential zones) is particularly interesting.
The Effect of Subsidized Housing on Values of Adjacent Housing
Authors: Guy Donald C. , Hysom John L. , Ruth Stephen R.
Published: October 2003

This is a case study of the effect of subsidized housing on the value of adjacent non‐subsidized housing. Four townhouse clusters in Fairfax County, Virginia, were selected for study because of the high degree of homogeneity between clusters. The clusters are all in the same community but vary in distance from subsidized housing. Sale prices were analyzed using a regression model which included distance from subsidized housing as an independent variable. Based on the results of the regression analysis, the authors conclude that the subsidized housing had a negative impact on the values of adjacent properties.
Valuation and Efficiency in the Market for Creatively Financed Houses
Authors: Dale‐Johnson David , Findlay M. Chapman , Schwartz Arthur L. , Kapplin Stephen D.
Published: October 2003

This paper examines two alternative approaches to valuing the impact of creative financing on housing prices. The cash equivalence adjustment which is the generally accepted approach is compared to an approach known as the financed fee valuation adjustment which is argued to be theoretically superior. A sample of 45 matched pairs of condominium sales in which one of the units is creatively financed and the other is conventionally financed is employed to test which model is most effective at explaining the market adjustment for creative financing. The authors are unable to reject the hypothesis that the housing market being examined is efficient and that the financed fee valuation adjustment is a superior model for valuing the impact of creative financing.
Maintenance Behavior of Large‐Scale Landlords and Theories of Neighborhood Succession
Authors: Elliott Donald S. , Quinn Michael A. , Mendelson Robert E.
Published: October 2003

This study integrates theories of landlord maintenance behavior with theories of neighborhood succession in a unified empirical model. The model permits a broad range of landlord responses to neighborhood decline including the possibility of increased maintenance expenditure as reported in recent empirical studies. Hypotheses are tested using a micro‐data set descriptive of 117 St. Louis rental properties.
A Further Note on Schools and Housing Values
Authors: Jud G. Donald
Published: October 2003

This paper provides further evidence on the relationship between public schools and housing values. Drawing on data from the Los Angeles and San Francisco areas, the paper presents estimates of an Oates‐type model of community housing values. Included in the model are measures of both student achievement and racial composition. The quality of public schooling, as measured by reading achievement, is found to be a strong, statistically significant determinant of community housing values, independent of student racial mix or socioeconomic background. Estimates of the model suggest that changes in achievement scores have substantial impacts on community housing values.
The Improvement Expenditures of Urban Homeowners: An Empirical Analysis
Authors: Boehm Thomas P. , Ihlanfeldt Keith R.
Published: October 2003

This paper presents evidence on the factors influencing the housing improvement expenditures of urban homeowners. In comparison to prior work, a more completely specified model was estimated. In particular, variables measuring the price of inputs and neighborhood quality were included and found to have a statistically significant impact on the maintenance and improvement expenditures of central city homeowners.
An Empirical Analysis of Tenant Selection Under Federal Rent Supplement Programs: A First Step
Authors: Jackson John D. , Jones Charlotte A. , Balsmeir Philip W.
Published: October 2003

The purpose of this study is to consider the question of whether characteristics of applicants for federally subsidized housing can be used in predicting whether one is accepted or rejected by management as a tenant. Using probit analysis, a statistical model was developed for use in assisting management in objectively screening applicants. Factors found significant in determining the probability of acceptance or rejection were credit ratings, character references, length of time employed, and student status. The percent of rent subsidized by government and sex of household head had little effect on applicant acceptance. Although a meaningful model for estimating the probability of eviction could not be developed, low eviction rates resulting from the tenant selection model suggest that it may serve as a reasonable proxy.
Do Syndications Pay More for Real Estate?
Authors: Beaton William , Sirmans C. F.
Published: October 2003

Syndications have been widely used in real estate investment in recent years. Some have argued that syndications have been paying significantly higher prices than other forms of business organization. Using a sample of apartment transactions, we tested for price differences among alternative ownership forms. The results indicate that the null hypothesis of equal price cannot be rejected.
Retail Leasehold Interests: A Contingent Claim Analysis
Authors: Chiang Raymond , Lai Tsong‐Yue , Ling David C.
Published: October 2003

This paper develops a contingent claim model to analyze certain aspects of retail leasehold contracts. The approach allows for the explicit consideration of risk without any ad hoc risk adjustment. Both “straight” leases and “percentage” leases are examined with the value of sales as the underlying asset. Each lease value is expressed as a combination of options on sales. The effects of the lease value's determinants and equilibrium risk measurements are also analyzed.
The Nearest Neighbors Appraisal Technique: An Alternative to the Adjustment Grid Methods
Authors: Isakson Hans R.
Published: October 2003

This study presents a new appraisal technique, dubbed the Nearest Neighbors Appraisal Technique, which vastly reduces the subjectivity of the traditional adjustment grid methods while eliminating the need to adjust for subject‐comparable differences on a piecemeal basis. Any number of appraisers who apply this technique to the same property at the same point in time will get the exact same estimate of value. The technique avoids piecemeal adjustments by capturing all subject‐comparable differences in a single measure. Using single‐family sales data, the technique is found to be more accurate than any of the adjustment grid methods and hedonic price regression estimation procedures.
Real Estate Valuation Models: Lender and Equity Investor Criteria
Authors: Cannaday Roger E. , Colwell Peter F.
Published: October 2003

The use of valuation models that focus on lender criteria has been growing in the appraisal field. In the rush to build lender criteria into real estate valuation models, equity investor criteria, expectations, and requirements occasionally have been ignored. The specific criteria considered in this paper are the loan‐to‐value ratio and the debt coverage ratio for lenders and the equity dividend rate for equity investors. Each of these three criteria may be a binding constraint on value.

Graphical analysis provides a framework within which major real estate valuation models (i.e., Ellwood, McLaughlin, Gettel, Lusht‐Zerbst, and Steele) are compared. A new valuation model (i.e., the Cannaday‐Colwell model) is developed which utilizes the equity dividend rate.

The three definitional models (i.e., McLaughlin, Gettel, and Steele) are found to be relevant only by mere coincidence. Each of these models simultaneously considers two of the three key criteria, completely eliminating the possibility of consideration of anything else; i.e., the models become tautological.

It is shown that the discounted cash flow based models (i.e., Ellwood, Lusht‐Zerbst, and Cannaday‐Colwell) each tell one‐third of the story. One of these models will be relevant depending upon whether the binding constraint is the maximum loan‐to‐value ratio, the minimum debt coverage ratio, or the minimum equity dividend rate. The relevant model is the one that yields the lowest value estimate of the three.
Risk and the Performance of Real Estate Investment Trusts: A Multiple Index Approach
Authors: Titman Sheridan , Warga Arthur
Published: October 2003

This paper analyzes the returns of a sample of Real Estate Investment Trusts and examines their risk‐adjusted performance using both single index (i.e., CAPM) and multiple index (i.e., APT) models. It is shown that while the performance rankings of the investment trusts are not very sensitive to the risk‐adjustment model, the actual performance measures do sometimes differ substantially. Unfortunately, because of the high volatility of these real estate investments, the differences in investment performance across trusts generally are not statistically significant.
Do Deposit Rates Cause Mortgage Loan Rates?: The Evidence from Causality Tests
Authors: Schnitzel Paul
Published: October 2003

This paper applies two familiar causality detection techniques to the issue of whether it is costs that determine prices or vice versa in the mortgage loan market. The question is posed in terms of causal priority: Are savings and loan deposit rates causally prior to mortgage loan rates or is it the other way around? For the time period prior to the onset of deposit interest rate deregulation, the evidence that emerges is consistent with the view that lenders raised their loan rates in response to higher deposit rates of interest. However, for the more recent period of deregulation, the evidence is not consistent with this view.
Portfolio Considerations in the Valuation of Real Estate
Authors: Webb James R. , Rubens Jack H.
Published: October 2003

When a real asset rises in price faster than inflation (as real estate did in the late 1970s) and rises significantly in price over an extended period (as real estate has done for the last decade and one‐half), it concerns valuation and investment professionals who fear about it being over‐valued. One of the reasons for such price performance may be an increase in demand due to the portfolio characteristics of the asset during the period of time in question. For real estate this means the proportion included in optimal portfolios should be significant and increasing as individual tax rates increase in an environment of increasing average tax rates.

This study uses six tax brackets (0%, 10%, 20%, 30%, 40%, 50%) and portfolios consisting of three traditional assets (NYSE common stocks, corporate bonds and small stocks) plus three types of real estate (residential, business and farmland) to demonstrate that this is what has transpired in the real estate markets. Optimal portfolio weights are derived for each asset for after‐tax portfolios. Real estate in general and residential real estate especially increased as a proportion of the optimal after‐tax portfolio as individual tax rates increased. Other studies are used to demonstrate an environment of increasing average tax rates.
A Trinomial Logit Analysis of Household Composition
Authors: Leppel Karen
Published: October 2003

This article analyzes the effects on the marriage and household composition decisions of characteristics of the householder and of the place of residence. High housing costs reduced the probability of living alone. For female householders, increases in income decreased the probability of living alone rather than with unrelated individuals; the reverse was true for male householders. An increase in income decreased the probability of marriage for female householders over twenty‐three years of age and increased the probability of marriage for male householders. Non‐white householders over forty were less likely to be married than white householders over forty.
The Effect of State Licensing Regulations on the Real Estate Brokerage Industry
Authors: Johnson Linda L. , Loucks Christine
Published: October 2003

An argument is often made that occupational licensure protects members of the regulated industry by limiting supply and raising earnings. The purpose of this study is to examine entry barriers within the real estate brokerage industry and to determine the effect of differing state entry requirements on the supply of practitioners, earnings, and quality of service provided. A simultaneous system of equations is developed where the number of licensees per capita, earnings, and quality are jointly estimated. Two‐stage least squares results support the premise that the consumer rather than the industry benefits from real estate prelicensing regulation with a higher quality of service. Significant evidence is not found to support the idea that the real estate industry regulations are self‐serving.
Real Estate Returns and Inflation
Authors: Hartzell David , Hekman John S. , Miles Mike E.
Published: October 2003

The ability of assets to protect an investor from purchasing power risk due to inflation has received a good deal of attention in the literature recently. The focus of much of this research has been on the properties of common stocks as inflation hedges. Bodie [1976] finds that the real return on equity is negatively related to both anticipated and unanticipated inflation; a similar result is obtained by Fama and Schwert [1977]. Bernard and Frecka [1983] examine individual common stock returns and find that the majority exhibit this negative relationship. This paper uses similar logic to examine the ability of a well‐diversified portfolio of real estate to hedge against anticipated and unanticipated inflation.
Efficient Real Estate Markets: Paradox or Paradigm?†
Authors: Gau George W.
Published: October 2003

This paper examines the question of whether an efficient markets paradigm should be adopted for the modelling and testing of real estate markets. It considers the perceived imperfections commonly suggested for these markets and reviews the existing weak form and semistrong form tests of real estate efficiency. Finally, it examines some of the likely implications for real estate research and practice resulting from the acceptance of such a paradigm.
Effects of Housing Codes on Local Housing Markets
Authors: Walden Michael L.
Published: October 2003

Housing codes are typically instituted in order to raise the average level of housing quality in a community. However, in doing so, the institution of a housing code likely has effects on other housing characteristics. Using data from municipalities in North Carolina, this study finds that municipalities with housing codes have higher average occupancy densities among all households and lower homeownership rates among low‐income households, but housing codes have no statistically discernible effect on housing values and expenditures. The results suggest that housing codes are not costless; most importantly, codes force consumers to trade housing quantity for quality.
Housing Quality and the Structure Tax: Evidence from Microdata
Authors: Tanzer Ellen P.
Published: October 2003

In a previous study [13] I showed theoretically that housing quality will rise when the structure tax rate falls if capital is a noninferior input. This result was supported empirically with aggregate SMSA‐level data. The present study reports empirical confirmation with microdata more appropriate for the theoretical hypothesis.
Predicting Failure of Savings & Loan Associations
Authors: Pantalone Coleen C. , Platt Marjorie B.
Published: October 2003

Early‐warning systems are intended to provide regulators with identification of problem institutions sooner than is possible with the present system of call reports and periodic on‐site examinations. Given an earlier indication of potential problems, resources can be focused on those institutions most in need of monitoring, thus potentially reducing both the number of failures and FSLIC financial assistance in the remaining failures. While some early‐warning systems were developed in the mid‐1970s for use by commercial bank regulators, very little attention has been focused on developing similar systems for the thrift industry. To address this issue, multiple discriminant analysis was used to develop an early‐warning system for savings and loan associations in the Boston district of the Federal Home Loan Bank system. The results suggest that use of this model would have given signals of impending trouble well before the actual failure occurred. Consequently, an early‐warning system could provide information to regulators sooner, permitting scarce resources to be allocated more effectively. In addition, earlier intervention could reduce the amount of FSLIC financial assistance required. By intervening earlier, FSLIC may be able to arrest the failure‐promoting activities in which the association is engaged.
Taxes, Points and Rationality in the Mortgage Market
Authors: Kau James B. , Keenan Donald
Published: October 2003

This paper addresses the issue of why discount points exist in the mortgage market. In the process of resolving these questions, a number of insights into the mortgage market are achieved. An important principle is that changes in loan structure due to points, prepayments or other deviations in the typical mortgage have no impact on the competitive rate of return. Thus, the essential role of points is not to raise the effective rate of return nor are they the purchase price a risk‐averter desires for an option to prepay. Instead it is taxes that play the critical role.
An Insurance Approach to Risk Analysis of Debt Home Equity Conversion Programs
Authors: Archer Wayne R. , Nye David J.
Published: October 2003

The use of home equity conversion debt creates a compounding obligation against the home that makes collateral deficiency a potentially dominant risk. Using an insurance methodology, an examination of this risk and its impact upon the potential for home equity conversion is conducted. The paper includes a consideration of how deficiency risk and maximum potential benefits are affected by the interaction of household characteristics with demographic and economic factors.
The Cyclic Behavior of the National Office Market
Authors: Wheaton William C.
Published: October 2003

A review of the post WWII data on national office building construction and vacancy, reveals a recurrent ten‐twelve year cycle. Specifying and estimating a structural econometric model for these series leads to several conclusions about this commercial real estate sector. First, the office market appears to “clear” quite slowly, and long‐run expectations play an important role in market behavior. Second, supply is definitely more responsive to market conditions than demand. Finally, a six‐year forecast suggests that the current over‐supply in the market will not go away as fast as in the past.
Dynamic Credit Rationing in the Home Mortgage Market
Authors: Kent Richard J.
Published: October 2003

In this study a model of dynamic credit rationing in the home mortgage market by a profit‐maximizing financial institution is developed.

In the 1960s and 1970s it was widely believed that credit rationing was very important in the mortgage market. The recent deregulation and innovation in financial markets is belived to have resulted in a significant weakening of these availability effects. For the model developed it is shown that deposit diversification, such as the introduction of money market accounts in 1978, would tend to reduce the amount of any dynamic credit rationing that was occurring.
The Affordability of Adequate Housing
Authors: Lerman Donald L. , Reeder William J.
Published: October 2003

A “quality‐based” measure of housing affordability problems employing the cost of housing just meeting adequacy standards is proposed as an improvement over the conventional “high” rent‐to‐income criterion. Based on Annual Housing Survey data, affordability difficulties grew between 1975 and 1983 by either measure. The conventional measure, however, overestimated the extent of quality‐based affordability difficulty for renters by 20% in 1975 and 24% in 1983 based upon Section 8 housing quality standards. In addition, 35% of rental households with an affordability problem by the conventional measure did not have an affordability problem by the quality‐based measure, while 19 to 23% of rental households found to have an affordability problem by the quality‐based measure were not so classified using the conventional measure.
Consumer Preferences in Housing Market Analysis: An Application of Multidimensional Scaling Techniques
Authors: Nelson Theron R. , Rabianski Joseph
Published: October 2003

The value of single–family housing is a function of demographic, economic and psychographic variables. Much work has been done on the objectively measurable criteria, but virtually none on the subjective, perceptual criteria. This study uses consumer‐supplied similarity measures of housing alternatives to develop a multidimensional perceptual “map” of the way consumers view housing choices. The dimensions of this perceptual space represent the evaluative criteria utilized, consciously or unconsciously, during the housing evaluation process. The analysis, although exploratory in nature, suggests that all perceptually defined market segments use the same evaluative construct; that market segments may be defined in terms of differences in the relative importance of each criterion; that market segments do not necessarily correspond to simple demographic measures; and that the major evaluative criteria in the perceptual process generally agree with those found in the literature based on objective measurements.
The First Twenty Years of AEEUEA
Authors: Kinnard William N. , Berkman Herman G. , Nourse Hugh O. , Weicher John C.
Published: October 2003

Editors' Note: At AREUEA's 1985 annual meeting, a special session was held to celebrate the 20th anniversary of AREUEA. The session was proposed by George Gau, the 1985 program chairman, and chaired by Patric H. Hender‐shott, the 1985 president. George and Pat selected four past presidents to discuss the first four five‐year periods of AREUEA's history. The presentations were so informative that the Board of Directors proposed publication in some form to preserve the historical record of AREUEA. With the financial assistance of the Homer Hoyt Institute and the efforts of Marc A. Weiss, we are pleased to publish a slightly edited version of the four presentations.

An appendix to this article lists the officers and members of AREUEA's Board of Directors since 1965 (any corrections should be drawn to the editors' attention). We note that four individuals have served on AREUEA's Board for a decade or longer: William B. Brueggeman, Hugh O. Nourse, Maury Seldin and Halbert C. Smith. All were president and either editor or secretary‐treasurer.
Another Look at Tenure Choice, Inflation, and Taxes
Authors: Follain James R. , Ling David C.
Published: October 2003

The purpose of this paper is to explore the impact of inflation on the demand for housing. The first part of the paper presents a theoretical model that identifies the effects of inflation on the after‐tax cost of housing and the choice between rental and owner‐occupied housing. The second part discusses the results of a simulation model that measures the effect of inflation on the aggregate demand for housing, the aggregate homeownership rate, and the price of housing. The paper concludes that while inflation can be expected to increase the aggregate demand for housing and the price of housing relative to the general price level, inflation should ultimately lead to lower rates of homeownership. A corollary that is probably more relevant today is that lower inflation rates should reduce the real value of the housing stock and increase the homeownership rate. The paper also contains forecasts of the impact of the Tax Reform Act (TRA) of 1986 upon housing demand and the probability of homeownership for a variety of households.
Housing Inventory Change and the Role of Existing Structures, 1961–1985
Authors: Hendershott Patric H. , Smith Marc T.
Published: October 2003

This paper makes two contributions. First, an internally consistent annual data set is constructed for the housing‐units identity. For the 1961–85 period, data are computed for completions, mobile home placements, the change in households, the change in vacancies, and, residually, net other additions (non‐new construction additions less losses). Our computed net other additions data for 1974 to 1980 are shown to be comparable to those implicit in the Annual Housing Survey data. Second, evidence is provided that net other additions play a major role in the short‐run equilibration of the demand and supply for housing units. Our evidence suggests that, on average, a surge in household formations is half satisfied by reduced losses or non‐new construction additions during the concurrent year.
The Duration of Marketing Time of Residential Housing
Authors: Haurin Donald
Published: October 2003

The marketing of unique durable goods such as housing presents a good example for the application of search theory. An optimal stopping rule strategy is employed to model sellers' behavior. The primary hypothesis is that the greater the atypicality of a house, the greater the expected variance of offers. Because a maximizing seller will wish to entertain more offers the greater is the variance, the marketing time of atypical houses will be relatively longer than that of standard houses. Using a sample of resale houses, the empirical study uses a failure time model to confirm the hypothesis. Extensions are mentioned, including discussions of the role of the list price and the limitations of the standard hedonic regression approach when applied to housing.
National Vacancy Rates and the Persistence of Shocks in U.S. Office Markets
Authors: Voith Richard , Crone Theodore
Published: October 2003

In this paper, we develop and estimate a model that decomposes the variance in office vacancy rates into market‐specific, time‐specific, and random components. The results indicate significant differences in natural vacancy rates across markets. We also find some persistence in deviations from these natural vacancy rates. The analysis is applied to both central business district (CBD) and suburban office markets. We find that natural vacancy rates differ across CBD markets and across suburban markets. Further, the persistence of disequilibrium in one CBD market seems to differ significantly from that in another. This is not shown to be true for suburban markets.
Housing Adjustment Costs: Their Impact on Mobility and Housing Demand Elasticities
Authors: Harmon Oskar R. , Potepan Michael J.
Published: October 2003

The role of housing adjustment costs in influencing mobility decisions, and the relationship between these and housing demands is not well understood. Here we try to examine how changes in adjustment costs as well as in such demand factors as income, influence the decision of households to adjust their housing consumption through moving. Empirically, we use a sample of recently moving homeowners from the PSID and provide evidence indicating adjustment costs are more important than other demand factors in influencing mobility decisions. We also argue that sample selection may bias estimates of housing demand elasticities when the sample is restricted to recent movers because the influence of adjustment costs in the mobility decision are not accounted for. Testing for this using the Heckman two‐stage procedure, however, showed this was not a significant problem.
THE SCENERY FLOW FOR HYPERBOLIC JULIA SETS
Authors: BEDFORD TIM , FISHER ALBERT M. , URBAŃSKI MARIUSZ
Published: October 2003

We define the scenery flow space at a point z in the Julia set J of a hyperbolic rational map $T : \mathbb{C} \to \mathbb{C}$ with degree at least 2, and more generally for T a conformal mixing repellor.

We prove that, for hyperbolic rational maps, except for a few exceptional cases listed below, the scenery flow is ergodic. We also prove ergodicity for almost all conformal mixing repellors; here the statement is that the scenery flow is ergodic for the repellors which are not linear nor contained in a finite union of real-analytic curves, and furthermore that for the collection of such maps based on a fixed open set U, the ergodic cases form a dense open subset of that collection. Scenery flow ergodicity implies that one generates the same scenery flow by zooming down towards almost every z with respect to the Hausdorff measure $H^d$, where d is the dimension of J, and that the flow has a unique measure of maximal entropy.

For all conformal mixing repellors, the flow is loosely Bernoulli and has topological entropy at most d. Moreover the flow at almost every point is the same up to a rotation, and so as a corollary, one has an analogue of the Lebesgue density theorem for the fractal set, giving a different proof of a theorem of Falconer.

2000 Mathematical Subject Classification: 37F15, 37F35, 37D20.
Identification and Characterization of the
emhABC
Efflux System for Polycyclic Aromatic Hydrocarbons in
Pseudomonas fluorescens
cLP6a
Authors: Hearn Elizabeth M. , Dennis Jonathan J. , Gray Murray R. , Foght Julia M.
Published: October 2003

The hydrocarbon-degrading environmental isolate
Pseudomonas fluorescens
LP6a possesses an active efflux mechanism for the polycyclic aromatic hydrocarbons phenanthrene, anthracene, and fluoranthene but not for naphthalene or toluene. PCR was used to detect efflux pump genes belonging to the resistance-nodulation-cell division (RND) superfamily in a plasmid-cured derivative,
P. fluorescens
cLP6a, which is unable to metabolize hydrocarbons. One RND pump, whose gene was identified in
P. fluorescens
cLP6a and was designated
emhB
, showed homology to the multidrug and solvent efflux pumps in
Pseudomonas aeruginosa
and
Pseudomonas putida
. The
emhB
gene is located in a gene cluster with the
emhA
and
emhC
genes, which encode the membrane fusion protein and outer membrane protein components of the efflux system, respectively. Disruption of
emhB
by insertion of an antibiotic resistance cassette demonstrated that the corresponding gene product was responsible for the efflux of polycyclic aromatic hydrocarbons. The
emhB
gene disruption did not affect the resistance of
P. fluorescens
cLP6a to tetracycline, erythromycin, trimethoprim, or streptomycin, but it did decrease resistance to chloramphenicol and nalidixic acid, indicating that the EmhABC system also functions in the efflux of these compounds and has an unusual selectivity. Phenanthrene efflux was observed in
P. aeruginosa
,
P. putida
, and
Burkholderia cepacia
but not in
Azotobacter vinelandii
. Polycyclic aromatic hydrocarbons represent a new class of nontoxic, highly hydrophobic compounds that are substrates of RND efflux systems, and the EmhABC system in
P. fluorescens
cLP6a has a narrow substrate range for these hydrocarbons and certain antibiotics.
Molecular Architecture of the Regulatory Locus
sae
of
Staphylococcus aureus
and Its Impact on Expression of Virulence Factors
Authors: Steinhuber Andrea , Goerke Christiane , Bayer Manfred G. , Döring Gerd , Wolz Christiane
Published: October 2003

We characterized the
sae
operon, a global regulator for virulence gene expression in
Staphylococcus aureus
. A Tn
917 sae
mutant was obtained by screening a Tn
917
library of the
agr
mutant ISP479Mu for clones with altered hemolytic activity. Sequence analysis of the
sae
operon revealed two additional open reading frames (ORFs) (ORF3 and ORF4) upstream of the two-component regulatory genes
saeR
and
saeS
. Four overlapping
sae
-specific transcripts (T1 to T4) were detected by Northern blot analysis, and the transcriptional initiation points were mapped by primer extension analysis. The T1, T2, and T3 mRNAs are probably terminated at the same stem-loop sequence downstream of
saeS
. The T1 message (3.1 kb) initiates upstream of ORF4, T2 (2.4 kb) initiates upstream of ORF3, and T3 (2.0 kb) initiates in front of
saeR
. T4 (0.7 kb) represents a monocistronic mRNA encompassing ORF4 only.
sae
-specific transcripts were detectable in all of the 40 different clinical
S. aureus
isolates investigated. Transcript levels were at maximum during the post-exponential growth phase. The
sae
mutant showed a significantly reduced rate of invasion of human endothelial cells, consistent with diminished transcription and expression of
fnbA
. The expression of type 5 capsular polysaccharide is activated in the
sae
mutant of strain Newman, as shown by immunofluorescence and promoter-reporter fusion experiments. In summary, the
sae
operon constitutes a four-component regulator system which acts on virulence gene expression in
S. aureus
.
Recognition of DNA by Three Ferric Uptake Regulator (Fur) Homologs inBacillus subtilis
Authors: Fuangthong Mayuree , Helmann John D.
Published: October 2003

Bacillus subtiliscontains three Fur homologs: Fur, PerR, and Zur. Despite significant sequence similarities, they respond to different stimuli and regulate different sets of genes. DNA target site comparisons indicate that all three paralogs recognize operators with a core 7-1-7 inverted repeat. The corresponding consensus sequences are identical at five or more of the seven defined positions. Using site-directed mutagenesis, the Per box at themrgApromoter was altered to mimic the core 7-1-7 motif of the Fur and Zur boxes. In vitro, themrgApromoter containing a Zur box was only recognized by Zur, as demonstrated by DNase I footprinting assays. In contrast, both Fur and PerR bound to themrgApromoter region containing a consensus Fur box. Expression analysis of these promoters is consistent with the in vitro data demonstrating as few as 1 or 2 base changes per half-site are sufficient to alter regulation. Similarly, the Fur box at thefeuApromoter can be converted into a Per or a Zur box by appropriate mutations. While both Fur and PerR could recognize some of the same synthetic operator sequences, no naturally occurring sites are known that are subject to dual regulation. However, the PerR-regulatedzosAgene is controlled from a regulatory region that contains both Per and Fur boxes. Although purified Fur protein bound to the candidate Fur boxes, Fur has little effect onzosAexpression—possibly due to the location of the Fur boxes relative to thezosApromoter. Together, our results identify two nucleotide positions that are important for the ability of PerR, Fur, and Zur to distinguish among the many closely related operator sites present in theB. subtilisgenome.
Investigation of the Role of Electrostatic Charge in Activation of the
Escherichia coli
Response Regulator CheY
Authors: Smith Jenny G. , Latiolais Jamie A. , Guanga Gerald P. , Citineni Sindhura , Silversmith Ruth E. , Bourret Robert B.
Published: October 2003

In a two-component regulatory system, an important means of signal transduction in microorganisms, a sensor kinase phosphorylates a response regulator protein on an aspartyl residue, resulting in activation. The active site of the response regulator is highly charged (containing a lysine, the phosphorylatable aspartate, two additional aspartates involved in metal binding, and an Mg
2+
ion), and introduction of the dianionic phosphoryl group results in the repositioning of charged moieties. Furthermore, substitution of one of the Mg
2+
-coordinating aspartates with lysine or arginine in the
Escherichia coli
chemotaxis response regulator CheY results in phosphorylation-independent activation. In order to examine the consequences of altered charge distribution for response regulator activity and to identify possible additional amino acid substitutions that result in phosphorylation-independent activation, we made 61 CheY mutants in which residues close to the site of phosphorylation (Asp57) were replaced by various charged amino acids. Most substitutions (47 of 61) resulted in the complete loss of CheY activity, as measured by the inability to support clockwise flagellar rotation. However, 10 substitutions, all introducing a new positive charge, resulted in the loss of chemotaxis but in the retention of some clockwise flagellar rotation. Of the mutants in this set, only the previously identified CheY13DK and CheY13DR mutants displayed clockwise activity in the absence of the CheA sensor kinase. The absence of negatively charged substitution mutants with residual activity suggests that the introduction of additional negative charges into the active site is particularly deleterious for CheY function. Finally, the spatial distribution of positions at which amino acid substitutions are functionally tolerated or not tolerated is consistent with the presently accepted mechanism of response regulator activation and further suggests a possible role for Met17 in signal transduction by CheY.
Genome Sequences of Two Closely Related
Vibrio parahaemolyticus
Phages, VP16T and VP16C
Authors: Seguritan Victor , Feng I-Wei , Rohwer Forest , Swift Mark , Segall Anca M.
Published: October 2003

Two bacteriophages of an environmental isolate of
Vibrio parahaemolyticus
were isolated and sequenced. The VP16T and VP16C phages were separated from a mixed lysate based on plaque morphology and exhibit 73 to 88% sequence identity over about 80% of their genomes. Only about 25% of their predicted open reading frames are similar to genes with known functions in the GenBank database. Both phages have
cos
sites and open reading frames encoding proteins closely related to coliphage lambda's terminase protein (the large subunit). Like in coliphage lambda and other siphophages, a large operon in each phage appears to encode proteins involved in DNA packaging and capsid assembly and presumably in host lysis; we refer to this as the structural operon. In addition, both phages have open reading frames closely related to genes encoding DNA polymerase and helicase proteins. Both phages also encode several putative transcription regulators, an apparent polypeptide deformylase, and a protein related to a virulence-associated protein, VapE, of
Dichelobacter nodosus
. Despite the similarity of the proteins and genome organization, each of the phages also encodes a few proteins not encoded by the other. We did not identify genes closely related to genes encoding integrase proteins belonging to either the tyrosine or serine recombinase family, and we have no evidence so far that these phages can lysogenize the
V. parahaemolyticus
strain 16 host. Surprisingly for active lytic viruses, the two phages have a codon usage that is very different than that of the host, suggesting the possibility that they may be relative newcomers to growth in
V. parahaemolyticus
. The DNA sequences should allow us to characterize the lifestyles of VP16T and VP16C and the interactions between these phages and their host at the molecular level, as well as their relationships to other marine and nonmarine phages.
Identification of Quorum-Sensing-Regulated Genes of
Burkholderia cepacia
Authors: Aguilar Claudio , Friscina Arianna , Devescovi Giulia , Kojic Milan , Venturi Vittorio
Published: October 2003

Quorum sensing is a regulatory mechanism (operating in response to cell density) which in gram-negative bacteria usually involves the production of
N
-acyl homoserine lactones (HSL). Quorum sensing in
Burkholderia cepacia
has been associated with the regulation of expression of extracellular proteins and siderophores and also with the regulation of swarming and biofilm formation. In the present study, several quorum-sensing-controlled gene promoters of
B. cepacia
ATCC 25416 were identified and characterized. A total of 28 putative gene promoters show CepR-C
8
-HSL-dependent expression, suggesting that quorum sensing in
B. cepacia
is a global regulatory system.
Prophage Contribution to Bacterial Population Dynamics
Authors: Bossi Lionello , Fuentes Juan A. , Mora Guido , Figueroa-Bossi Nara
Published: October 2003

Cocultures of
Salmonella
strains carrying or lacking specific prophages undergo swift composition changes as a result of phage-mediated killing of sensitive bacteria and lysogenic conversion of survivors. Thus, spontaneous prophage induction in a few lysogenic cells enhances the competitive fitness of the lysogen population as a whole, setting a selection regime that forces maintenance and spread of viral DNA. This is likely to account for the profusion of prophage sequences in bacterial genomes and may contribute to the evolutionary success of certain phylogenetic lineages.
A Transcriptional Pause Synchronizes Translation with Transcription in the Tryptophanase Operon Leader Region
Authors: Gong Feng , Yanofsky Charles
Published: October 2003

Regulation of transcription of the tryptophanase operon requires that translation of its leader peptide coding region,
tnaC
, be coupled with its transcription. We show in vitro that a transcription pause site exists at the end of the
tnaC
coding region and that translation of
tnaC
releases the paused transcription complex, coupling transcription with translation.
Thymine at —5 Is Crucial for
cpc
Promoter Activity of
Synechocystis
sp. Strain PCC 6714
Authors: Imashimizu Masahiko , Fujiwara Shoko , Tanigawa Ryohei , Tanaka Kan , Hirokawa Takatsugu , Nakajima Yuji , Higo Junichi , Tsuzuki Mikio
Published: October 2003

The levels of transcripts of the
cpc
operon were highly reduced in a PD-1 mutant of cyanobacterium
Synechocystis
sp. strain PCC 6714. This was due to a substitution of C for T that occurred at 5 bp upstream of the transcription initiation site of the
cpc
operon. Any substitution for T at the −5 position drastically reduced both in vivo and in vitro promoter activity in cyanobacterium
Synechococcus
sp. strain PCC 7942 but not the in vivo activity in
Escherichia coli
. This suggests that the requirement of −5T appears to be specific for a cyanobacterial RNA polymerase-promoter combination.
Bacteriophage ST64B, a Genetic Mosaic of Genes from Diverse Sources Isolated fromSalmonella entericaSerovar Typhimurium DT 64
Authors: Mmolawa Princess T. , Schmieger Horst , Heuzenroeder Michael W.
Published: October 2003

The complete sequence of the double-stranded DNA (dsDNA) genome of theSalmonella entericaserovar Typhimurium ST64B bacteriophage was determined. The 40,149-bp genomic sequence of ST64B has an overall G+C content of 51.3% and is distinct from that of P22. The genome architecture is similar to that of the lambdoid phages, particularly that of coliphage λ. Most of the putative tail genes showed sequence similarity to tail genes of Mu, a nonlambdoid phage. In addition, it is likely that these tail genes are not expressed due to insertions of fragments of genes related to virulence within some of the open reading frames. This, together with the inability of ST64B to produce plaques on a wide range of isolates, suggests that ST64B is a defective phage. In contrast to the tail genes, most of the head genes showed similarity to those of the lambdoid phages HK97 and HK022, but these head genes also have significant sequence similarities to those of several other dsDNA phages infecting diverse bacterial hosts, includingEscherichia,Pseudomonas,Agrobacterium,Caulobacter,Mesorhizobium, andStreptomyces.This suggests that ST64B is a genetic mosaic that has acquired significant portions of its genome from sources outside the genusSalmonella.
rRNA Antitermination Functions with Heat Shock Promoters
Authors: Seoh Hyuk Kyu , Weech Michelle , Zhang Ning , Squires Catherine L.
Published: October 2003

Transcription antitermination in the rRNA operons of
Escherichia coli
requires a unique nucleic acid sequence that serves as a signal for modification of the elongating RNA polymerase, making it resistant to Rho-dependent termination. We examined the antitermination ability of RNA polymerase elongation complexes that had initiated at three different heat shock promoters,
dnaK
,
groE
, and
clpB
, and then transcribed the antitermination sequence to read through a Rho-dependent terminator. Terminator bypass comparable to that seen with σ
70
promoters was obtained. Lack of or inversion of the sequence abolished terminator readthrough. We conclude that RNA polymerase that uses σ
32
to initiate transcription can adopt a conformation similar to that of σ
70
-containing RNA polymerase, enabling it to interact with auxiliary modifying proteins and bypass Rho-dependent terminators.