bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of the Recent Performance of Publicly Traded Real Property Portfolios and Common Stock
Authors: Martin John D. , Cook Douglas O.
Published: October 2003

In this study we compare the returns earned by investments in publicly traded limited partnerships (PTLPs), finite life equity REITs, and traditional equity REITs with those resulting from investing in common stocks (proxied by closed‐end mutual funds). Performance comparisons are made using generalized stochastic dominance (GSD). This tool avoids the joint hypothesis problem that arises when an asset pricing model is used as a performance benchmark. The results of the analysis indicate that the performance of the closed‐end mutual funds was preferred to that of the individual equity REITs (both traditional and finite life) and PTLP securities by a wide array of risk‐averse investors. This result was most pronounced following the passage of the Tax Reform Act of 1986 which severely restricted the tax deductibility of real estate losses. When the equity REITs were combined into portfolios, their performance dominated the mutual funds during the 1980–85 period. Further, the PTLP portfolio returns were preferred to several of the mutual funds even in the post‐1985 period. These findings reflect the fact that the securitized real property portfolios studied are not as well diversified as mutual funds. However, the mutual funds remained the dominant investment alternative in the post‐1986 period.
Optimal Comparable Selection and Weighting in Real Property Valuation
Authors: Vandell Kerry D.
Published: October 2003

This paper formalizes certain aspects of the sales comparison approach to valuation that heretofore have been quite ad hoc. Specifically, it applies statistical theory to decisions about how many comparables to select, what the criteria for comparable selection should be, and how the proper weights for each adjusted value estimate can be determined such that the final value estimate is both unbiased and of minimum variance. Several results are derived that run counter to conventional practice; for example, it may not always be optimal to consider first the “best” comparables because of a lack of independence among their adjusted value estimates. Furthermore, it is always desirable to consider more comparables (regardless of how “bad”) so long as their adjusted value estimates are optimally weighted in the final value estimate. Finally, weights usually selected for “inferior” comparables are typically too small. A final exercise empirically applies the methodology to a sample of sales.
Strategies and Performance in the Thrift Industry: 1979–1987
Authors: Rudolph Patricia M. , Topping Sharon
Published: October 2003

From the late seventies until 1989, the regulatory environment of the thrift industry was changed from one that permitted little managerial discretion to one in which managers were allowed to choose from a wide variety of lending and borrowing activities. In this article, cluster analysis is used to separate thrifts into strategic groups based on the extent to which they utilized their new powers. Differences among the groups and the relationship between group membership and performance is tested over the period 1979–1987 using analysis of variance.
House Price Indexes: Issues and Results
Authors: Haurin Donald R. , Hendershott Patric H.
Published: October 2003

AREUEA is pleased to acknowledge the support of the National Association of REALTORS for this special issue on house prices. We are particularly grateful to John Tuccillo, Senior Vice President and Chief Economist at NAR, for recognizing the importance of this emerging research area. The editors also acknowledge the support of their colleges at The Ohio State University and of the Homer Hoyt Institute.
Housing Price Indices Based on All Transactions Compared to Repeat Subsamples
Authors: Clapp John M. , Giaccotto Carmelo , Tirtiroglu Dogan
Published: October 2003

The set of real properties sold during a given period of time may be subdivided into several subsets comprising those properties that sold only once, only twice, and three or more times. The major reason for subdividing the sample is to allow estimation of residential price indices by the repeat‐sales methodology. The purpose of this paper is to compare price indices estimated with the repeat subsample to indices based on the entire sample.

Our data for five metropolitan areas indicate that cumulative price trends for the repeat subsamples can differ from the full samples over periods ranging from two to ten quarters. While short‐term price trends can differ widely, there are no systematic differences among the samples over periods of three years or more. The data indicate that arbitrage typically forces prices for the repeat sample to grow at the same rate as those for the full sample. Whether this would be the case in areas experiencing greater disequilibrium than our towns in the Hartford area is uncertain.
On Choosing Among House Price Index Methodologies
Authors: Case Bradford , Pollakowski Henry O. , Wachter Susan M.
Published: October 2003

This paper compares housing price indices estimated using three models with several sets of property transaction data. The commonly used hedonic price model suffers from potential specification bias and inefficiency, while the weighted repeat‐sales model presents potentially more serious bias and inefficiency problems. A hybrid model combining hedonic and repeat‐sales equations avoids most of these sources of bias and inefficiency. This paper evaluates the performance of each type of model using a particularly rich local housing market database. The results, though ambiguous, appear to confirm the problems with the repeat sales model but suggest that systematic differences between repeat‐transacting and single‐transacting properties lead to bias in the hedonic and hybrid models as well.
Nonparametric Estimation of Dynamic Hedonic Price Models and the Construction of Residential Housing Price Indices
Authors: Meese Richard , Wallace Nancy
Published: October 2003

Parametric specifications for hedonic price equations are estimated using a data set from Alameda and San Francisco Counties and are compared to estimates using a nonparametric technique called locally weighted regression, LWR. LWR permits flexible estimation of the hedonic's curvature at median attributes and is less sensitive than standard regression techniques to the influence of unusual observations. The technique also avoids imposing a single functional form across time and municipalities. The LWR estimates of municipality‐specific hedonics are then used to obtain implicit prices for housing attributes and to derive municipality‐specific price indices. The results of extensive diagnostic checks of our technique are also reported.
New Evidence on Home Prices from Freddie Mac Repeat Sales
Authors: Abraham Jesse M. , Schauman William S.
Published: October 2003

The weighted repeat sales price index methodology recently reported in Case and Shiller [5][6] is applied to a dataset of over eight million loans bought by the Federal Home Loan Mortgage Corporation over the last twenty years. Regional price indices are reported and compared to indices from other sources. Statistical issues in the creation of the index, both technical and due to sample selectivity of the Freddie Mac dataset, are extensively discussed. It is found that the new index grows at a rate similar to other indices up until 1985, after which time it grows at a significantly higher rate.
The Measurement and Determinants of Single‐Family House Prices
Authors: Peek Joe , Wilcox James A.
Published: October 2003

We assess the conceptual and empirical features of a number of house price series for the United States. We then calculate a measure of the net up‐grading of the existing stock of houses that took place during the 1950–1989 period and adjust price indexes for this net increase in quality. Judgments about the trend, volatility, and determinants of house prices are shown to depend crucially on which price series is used. The Freddie Mac upgrade‐adjusted house price measure rose 5.7% over the past four decades, falling 7.7% from 1950 through 1970 before rising 14.5% from 1970 through 1989. Real house prices declined in the early 1980s due to the increase in real after‐tax interest rates and the decline in real materials costs. The recovery of house prices in the late 1980s is attributed to lower unemployment and real after‐tax interest rates and particularly to demographic factors associated with the aging of baby boomers.
User Cost and the Demand for Housing Attributes
Authors: Gill H. Leroy , Haurin Donald R.
Published: October 2003

A number of studies have related changes in the demand for housing to changes in user cost. All have treated housing as a composite good rather than as a bundle of characteristics. We consider the effect of changing user cost on the demand for the component characteristics of owner‐occupied housing, and, given information about the supply of the characteristics, we predict implicit price responses. An empirical test of our model indicates that reductions in user cost result in higher real prices for the non‐replicable attributes of housing, examples being location and access to fixed amenities. In contrast, the price of attributes that are perfectly elastic in supply are not affected by changes in user costs. We conclude that the effects of changing user cost are not uniform across housing types and locations, thus generating the appearance of housing submarkets.
House Prices and Regional Real Estate Cycles: Market Adjustments in Houston
Authors: Smith Barton A. , Tesarek William P.
Published: October 2003

Real estate cycles often generate sharp swings in real housing prices, price changes that cannot be adequately described by a single statistic such as median home values. Instead, the entire structure of prices across all quality levels must be examined. This paper analyzes the price impact of the Houston, Texas, real estate bust. It shows that the average price of housing fell, and that the structure of the housing price function itself changed. Changes in the marginal price of housing were probably more significant to the market equilibrating process than the decline in average price alone.
Rates of Return on Housing of Low‐and Moderate‐Income Owners
Authors: Pollakowski Henry O. , Stegman Michael A. , Rohe William
Published: October 2003

While long‐term returns to capital invested in owner‐occupied housing have been competitive with other investment alternatives, no evidence exists on the market performance of the owner‐occupied housing in which low‐ and moderate‐income households would be most likely to invest. This article thus attempts to answer the question of whether the “affordable housing units” that are relevant to policy discussions concerning low‐ and moderate‐income homeownership have experienced different rates of price appreciation than have higher valued dwellings. The national file of the American Housing Survey is used to estimate appreciation rates by value class in representative U.S. housing markets. We find that for the period 1974 through 1983 appreciation rates for lower valued housing were generally about equal to those for higher valued housing.
Geographical Cost of Living Differences: An Update
Authors: McMahon Walter W.
Published: October 2003

This article develops a method for estimating current geographical differences in the cost of living index for all states for 1981–1990. These estimates based on BLS data are shown to correspond closely to statewide cost of living estimates for 1989 based on the American Chamber of Commerce Research Association data for selected cities.

Living costs are highest in Hawaii, Alaska, Connecticut, Washington D.C., New Jersey, Massachusetts, New York, and California. They are lower in Mississippi, West Virginia, Arkansas, Idaho, and Utah. The basic pattern persists since 1977 with shifts related to economic growth rates.
Local House Price Indexes: 1982–1991
Authors: Haurin Donald R. , Hendershott Patric H. , Kim Dongwook
Published: October 2003

We begin with a description of three house price panel data sets for the period 1982 to 1991. Next, we estimate a model that assumes the three sources are derived from an underlying unobserved price series, and we construct composite indexes that report house prices for 135 locations. These series can be used either as explanatory variables in studies of household formation, housing demand, and migration or to test models of the determinants of spatial and intertemporal variations in house prices. Finally, we construct regional series (based, alternatively, on census and Salomon Brothers regions) and two national aggregates and describe their movements. Our series are compared to other local, regional, and national series.
Modelling Mortgage Terminations in Turbulent Times
Authors: Cooperstein Richard L. , Redburn F. Stevens , Meyers Harry G.
Published: October 2003

Techniques used to predict mortgage defaults during a relatively stable period proved less successful during the turbulent financial cycle of the early 1980s. An alternative specification of the relationship between defaults, homeowner equity, and interest‐rate movements better captures the effect of interest rates on default probability. Results confirm the powerful effect of equity on mortgage defaults and the strong, but asymmetric, influence of interest rates on both defaults and prepayments. The new specification allows direct measurement of the interest‐rate effect on defaults, distinguishing the effect when rates rise or fall.
Recoveries on Distressed Real Estate and The Relative Efficiency of Public versus Private Management
Authors: Curry Timothy , Blalock Joseph , Cole Rebel
Published: October 2003

This study examines average recoveries from distressed commercial real estate assets held by FSLIC receiverships, and explores differences in the relative efficiency of public versus quasi‐private and private entities in the management of these assets. It finds that properties located in markets with rising per capita income and properties that were judged to be less difficult to manage and sell provided higher recoveries, while properties with smaller writedowns prior to government takeover provided lower recoveries. The analysis also provides evidence that quasi‐private management by the Federal Asset Disposition Agency provided higher mean recoveries, while private management by contractors provided lower mean recoveries than did public management by FSLIC receivership staff.
Risk and the User Cost of Housing Services
Authors: Chinloy Peter
Published: October 2003

This paper derives a risk‐adjusted user cost for housing services, capable of application in price indexes, demand, and the measurement of income and returns to homeownership. The risk‐adjusted user cost is the after‐tax sum of an interest rate and a risk premium, less expected capital gains. Expected capital gains are based on a factor pricing specification. It is shown that both national and local factors affect capital gains on housing.
A Price Dispersion Equilibrium in a Spatially Differentiated Housing Market with Search Costs
Authors: Read Colin
Published: October 2003

An equilibrium model of search in a spatially differentiated rental housing market is formulated that predicts both rent dispersion and equilibrium vacancies. The equilibrium rent distribution is determined on the landlord's (rental supply) side given tenants' search strategies. Then tenants' optimal search strategy, denned by the share of the market a tenant searches, is determined given the costs and benefits of search and the distribution of landlords' rents. The equations of supply and demand for rental units are then combined to derive a costly information, free‐entry Nash equilibrium in the market rents. Finally, the sensitivity of equilibrium vacancies and rents to changes in search costs and other exogenous parameters is explored.
The Multiple Listing Service, Commission Splits, and Broker Effort
Authors: Miceli Thomas J.
Published: October 2003

This paper examines the impact of split commissions on broker effort in MLS sales. The joint effort of brokers to find a buyer for a given listing is maximized when the broker who locates a buyer first receives the entire commission. In contrast, splitting the commission between the listing and finding broker (when they differ) maximizes the joint profits of brokers. When competition among brokers to acquire listings is considered, however, the split brokers most prefer entails a smaller (though still positive) share for the listing broker in order to reduce wasteful competition for listings. While sellers still prefer to pay only the broker who finds a buyer, brokers may not be willing to acquire and share listings under such an arrangement.
The Gains from Corporate Selloffs: The Case of Real Estate Assets
Authors: Glascock John L. , Davidson Wallace N. , Sirmans C. F.
Published: October 2003

Recent financial economics literature has hypothesized that variations in market structure influence the distribution of gains from corporate restructuring between buyers and sellers. We test this hypothesis using data on restructuring involving real estate assets by isolating the effects depending on multiple versus single bidders, acquisition frequency and transaction type. While we find gains for both buyers and sellers, the buyers gain only when they make few purchases. Those firms pursuing an acquisition strategy show no gains around the specific acquisition announcements. Additionally, both buyers and sellers are more likely to have a positive reaction to the announcement when the transaction is property rather than a division or subsidiary.
Corporate Headquarters Relocation: Evidence from the Capital Markets
Authors: Alli Kasim L. , Ramirez Gabriel G. , Yung Kenneth
Published: October 2003

This paper assesses the stock market reaction to announcements of corporate headquarters relocations and examines financial and geographical factors related to wealth effects and factors that influence the decision to relocate corporate headquarters. The results indicate that announcements of relocations are associated with significant positive stock price effects. On average, the stock price of relocating firms increases by 1.29% during the two‐day period around the announcement. Abnormal returns are positively related to the availability of labor and negatively related to the cost of living in the new location and the change in employment levels. A logit analysis indicates that the probability of a firm relocating is partially determined by the firm size and the rental expenses/sales ratio. The results also indicate that firm size, the employment/asset ratio levels, and listing in the NYSE/AMEX affect the decision to relocate to a Fortune‐ranked city. Finally, firms relocating to Fortune‐ranked cities are characterized by a high level of insider ownership relative to firms moving to non‐ranked cities.
Developmental Aspects of Spinal Locomotor Function: Insights from Using the in vitro Mouse Spinal Cord Preparation
Authors: Whelan Patrick J.
Published: October 2003

Over the last five years, rapid advances have been made in our understanding of the location, function, and recently, organization of the central pattern generator (CPG) for locomotion. In the mammal, the use of the neonatal rat has largely contributed to these advances. Additionally, the use of the in vitro mouse spinal cord preparation is becoming more common, catalysed in part by the potential for the use of genetic approaches to study locomotor function. Although tempting, it is necessary to resist the a priori assumption that the organization of the spinal CPG is identical in the rat and mouse. This review will describe the development of locomotor‐like behaviour in the mouse from embryonic day 12 to postnatal day 14. While there are still many gaps in our knowledge, compared with the rat, the in vitro mouse appears to follow a qualitatively similar course of locomotor development. The emphasis in this review is the use or potential use of the mouse as a complement to existing data using the neonatal rat preparation.
Contribution of Ionic Currents to Magnetoencephalography (MEG) and Electroencephalography (EEG) Signals Generated by Guinea‐Pig CA3 Slices
Authors: Murakami Shingo , Hirose Akira , Okada Yoshio C.
Published: October 2003

A mathematical model was used to analyse the contributions of different types of ionic currents in the pyramidal cells of longitudinal CA3 slices to the magnetic fields and field potentials generated by this preparation. Murakami et al. recently showed that a model based on the work of Traub et al. provides a quantitatively accurate account of the basic features of three types of empirical data (magnetic fields outside the slice, extracellular field potentials within the slice and intracellular potentials within the pyramidal neurons) elicited by stimulations of the soma and apical dendrites. This model was used in the present study to compute the net current dipole moment (Q) due to each of the different voltage‐ and ligand‐gated channels in the cells in the presence of fast GABAA inhibition. These values of Q are proportional to the magnetic field and electrical potential far away from the slice. The intrinsic conductances were found to be more important than the synaptic conductances in determining the shape and magnitude of Q. Among the intrinsic conductances, the sodium (gNa) and delayed‐rectifier potassium (gK(DR)) channels were found to produce sharp spikes. The high‐threshold calcium channel (gCa) and C‐type potassium channel (gK(C)) primarily determined the overall current waveforms. The roles of gCa and gK(C) were independent of small perturbations in these channel densities in the apical and basal dendrites. A combination of gNa, gK(DR), gCa, and gK(C) accounted for most of the evoked responses, except for later slow components, which were primarily due to synaptic channels.
Denervation of Carotid Baro‐ and Chemoreceptors in Humans
Authors: Timmers Henri J. L. M. , Wieling Wouter , Karemaker John M. , Lenders Jacques W. M.
Published: October 2003

Experimental denervation in animals has shown that carotid baro‐ and chemoreceptors play an eminent role in maintaining blood pressure and blood gas homeostasis. Denervation of carotid sinus baro‐ and chemoreceptors in humans may occur as a complication of invasive interventions on the neck or after experimental surgical treatment in asthma. In this topical review, the short‐ and long‐term effects of carotid baro‐ and chemoreceptor denervation on the control of circulation and ventilation in humans are discussed. Carotid baroreceptor denervation in humans causes a persistent decrease in vagal and sympathetic baroreflex sensitivity and an increase in blood pressure variability; however, carotid denervation does not lead to chronic hypertension. Therefore, although carotid baroreceptors contribute to short‐term blood pressure control, other receptors are able to maintain normal chronic blood pressure levels in the absence of carotid baroreceptors. Conversely, carotid chemoreceptor denervation leads to permanent abolition of normocapnic ventilatory responses to hypoxia and reduced ventilatory responses to hypercapnia.
Exercise‐Induced Changes in Plasma Composition Increase Erythrocyte Na+,K+‐ATPase, but not Na+–K+–2Cl− Cotransporter, Activity to Stimulate net and Unidirectional K+ Transport in Humans
Authors: Lindinger Michael I. , Grudzien Simon P.
Published: October 2003

We tested the hypothesis that exercise‐induced changes in plasma composition result in peak stimulation of erythrocyte unidirectional K+ (JK,in) and net K+ (JK,net) transport within the first 120 s. In experimental series 1 (7 men; 2 women), plasma [K+] was continuously measured in vitro (37 °C) after the addition of red blood cells (RBCs) obtained from rested subjects (resting RBCs) into an exercise‐simulated plasma (ESP; increased plasma osmolality, [K+], [H+], [lactate] and [adrenaline] (epinephrine)), and JK,net calculated. In experimental series 2 (7 men; 4 women), resting RBCs were incubated in true exercise plasma (TEP) obtained after two 30 s bouts of high intensity leg cycling exercise to determine JK,net and JK,in (via RBC 86Rb accumulation). JK,net of resting RBCs increased from 0.9 ± 28.7 in resting plasma to 285 ± 164 mmol (l RBCs)−1 h−1 in ESP and to 178 ± 60 mmol (l RBCs)−1 h−1 after 10 s in TEP. Both JK,net and JK,in peaked within 10 s of incubation and decreased rapidly during the initial 120 s. The use of inhibitors for the Na+,K+‐ATPase (ouabain) and the Na+‐K+‐2Cl− cotransporter (NKCC; bumetanide) indicated that rapid increases in JK,in and JK,net upon incubation of resting RBCs in TEP were due primarily to increased Na+,K+‐ATPase activity; the NKCC appeared to be involved only when the Na+,K+‐ATPase was blocked. It is concluded that RBCs rapidly increase JK,in and JK,net in response to exercise‐induced changes in plasma composition.
Effect of Cement Content and Curing Period on Properties of DUT-1 Synthetic Model Ice
Authors: Li Zhijun , Wang Yongxue , Wang Xiwen , Li Guangwei
Published: October 2003

The effects of cement content and curing period on a new synthetic model ice, DUT-1, are reported. The cement (450#) contents were 10%, 11%, 12%, 13%, 14%, 15% and 16% by dry weight of mixture material. Eight different curing periods were used: 66 h, 92 h, 115 h, 139 h, 163 h, 186 h, 211 h and 235 h. Physical and mechanical properties, such as density, compressive strength, flexural strength, and elastic modulus, were determined. The density and mechanical parameters were found to increase with increasing cement content, whereas the durations of curing period under normal air temperature resulted in increasing these properties to a maximum value, then decreasing values.
Partial Reconstruction of Wavelet Transforms: A Technique for Quantifying Amplitude Envelopes of Riser Response Modes
Authors: Pelstring J. A. , Waller E. E. , Jordan D. A. , Miksad R. W.
Published: October 2003

Knowledge of the frequencies and amplitudes and single-mode versus multi-mode behavior of deepwater riser responses is important for accurate fatigue analysis. The extraction of this information from measured riser responses is a significant challenge given the complexity of the phenomena involved with riser vibrations. An existing technique for obtaining modal amplitudes, wavelet ridge extraction (WRE), has been shown to return a smoothed version of the actual amplitude envelope, resulting in attenuated peak values. In this paper, we introduce a new wavelet-based technique, partial reconstruction of wavelet transforms, for accurately extracting amplitude envelopes of the modes from multi-mode signals. The partial reconstruction technique is proposed to circumvent problems presented by WRE by making use of information available from the inverse wavelet transform. It is demonstrated with synthesized test signals that the new technique provides much more accurate modal envelopes than does WRE. Finally, to illustrate the technique for practical riser response signals, the partial reconstruction technique is applied to representative acceleration fluctuations measured from a drilling riser in the Schiehallion field.
Fabrication of device-grade silicon-on-insulator material from appropriate matches of low oxygen implantation dose and acceleration energy
Authors: Chen Meng , Wang Xiang , Chen Jing , Dong Yeming , Yi Wangbin , Liu Xianghua , Wang Xi
Published: October 2003

We report the formation of high-quality silicon-on-insulator materials using separation-by-implantation-of-oxygen (SIMOX) technology, with doses ranging from 1.8 to 13.5×1017 cm−2 at acceleration energies of 45–160 keV, and subsequently annealed at a high temperature of over 1300 °C in an oxygen and argon atmosphere for 5 h. The microstructure evolution of SIMOX wafers was characterized by Rutherford backscattering spectroscopy, transmission electron microscopy, modified enhanced Secco, Cu plating, and spectroscopic ellipsometry. The study reveals a series of good matches of dose–energy combination at acceleration energies of 45–160 keV with doses of 1.8–5.5×1017 cm−2, in which the SIMOX wafers have good crystallinity of the top silicon, a sharp Si/SiO2 interface, and a high-integrity buried oxide layer with a low pinhole density and few detectable silicon islands. Furthermore, the higher the oxygen dose, the higher the implanted energy required for the formation of a Si-island-free buried oxide layer. The mechanism of an appropriate dose–energy match is discussed.
In-plane vector magnetometry on rectangular Co dots using polarized neutron reflectivity
Authors: Temst K. , Van Bael M. J. , Swerts J. , Buntinx D. , Van Haesendonck C. , Bruynseraede Y. , Fritzsche H. , Jonckheere R.
Published: October 2003

We have measured the off-specular polarized neutron reflectivity of a periodic array of rectangular polycrystalline magnetic Co dots, which were prepared by a combination of electron beam lithography and molecular beam deposition. The dots have strong shape anisotropy, imposed by a length-to-width ratio of 4:1. The intensity of the first-order off-specular satellite reflection was monitored as function of the magnetic field parallel to the rows of dots, allowing us to analyze the magnetization reversal process using the four spin-polarized scattering cross sections.
Crystallization of amorphous silicon films by Cu-field aided rapid thermal annealing
Authors: Kang Moon-Soo , Kim Young-Bae , Ahn Jin-Yong , Choi Duck-Kyun
Published: October 2003

In this study, a technique, field aided rapid thermal annealing (FARTA) was proposed to crystallize the amorphous silicon films for a substantially short process time at low temperature. A spike shape pulsed rapid thermal annealing has been added to the field aided lateral crystallization (FALC) of amorphous silicon films deposited by plasma enhanced chemical deposition on glass. By adopting the FARTA process, directional crystallization of a-Si could be successfully achieved at 450 °C within a few hundreds of seconds. Other advanced crystallization methods such as FALC and metal induced lateral crystallization (MILC) normally require several hours for the same degree of crystallization even at 500 °C. Crystallization velocity using the FARTA process was measured to be 186.3 μm/h when the a-Si experienced 10 cycles of 60 s 450 °C thermal bias followed by 1 s 750 °C spike anneal. This value was six times faster than that by the MILC process at the same heating condition. From this study we found that both an electric field and the spike anneal are necessary for the crystallization of a-Si with a low thermal budget.
Electrostatic potential for a hyperbolic probe tip near a semiconductor
Authors: Feenstra R. M.
Published: October 2003

The electrostatic potential resulting from a metallic probe tip near a semiconductor is examined. A solution is formulated assuming circular symmetry and using prolate spheroidal coordinates in the vacuum and Cartesian coordinates in the semiconductor. The result is most directly applied to the case of a hyperbolic probe tip, but other shapes (for example, a small hemispherical protrusion on the tip apex) can also be handled. Numerical results are given for representative cases that might be encountered in scanning probe microscopy.
Fabrication of nanoscale gratings with reduced line edge roughness using nanoimprint lithography
Authors: Yu Zhaoning , Chen Lei , Wu Wei , Ge Haixiong , Chou Stephen Y.
Published: October 2003

Line edge roughness is an important factor contributing to the problem of performance degradation in various nanoscale devices. We have developed two smoothing techniques based on nanoimprint lithography for the fabrication of nanoscale gratings with significantly reduced line edge roughness. Compared with other smoothing techniques reported before, our methods are low-cost, effective, and easy to implement. These technologies have been used for the fabrication of smooth nanochannels for stretching and separating double-stranded DNA molecules. They are also compatible with a wide range of materials and applications, including subwavelength optics, bioanalysis and micro/nano-fluidic systems.
Magnetic properties of Mn-implanted AlGaP alloys
Authors: Overberg M. E. , Thaler G. T. , Frazier R. M. , Abernathy C. R. , Pearton S. J. , Rairigh R. , Kelly J. , Theodoropoulou N. A. , Hebard A. F. , Wilson R. G. , Zavada J. M.
Published: October 2003

Ion implantation of Mn at concentrations of 1–5 at. % was performed in AlxGa1−xP:C (x=0, 0.24, 0.38, and 0.54) epilayers grown by gas source molecular beam epitaxy. Ferromagnetic-like ordering at 300 K was observed for Mn doses up to 3 at. % for all Al subfractions in superconducting quantum interference device measurements. The calculated magnetic moment was found to peak at 3 at. % Mn in plots of magnetization versus Mn for all four Al subfractions. For a given Mn concentration, the magnetic moment was found to initially increase then decrease in plots of magnetization versus Al subfraction. Structural characterization revealed the presence of the Mn2P and Mn3Ga phases in Al0.54Ga0.46P:C layers implanted with 5 at. % Mn, while no second phases were observed in any other combinations of Al and Mn. A substantial increase in magnetic ordering temperature predicted by theory for AlxGa1−xP:C films compared to GaP:C films with Mn incorporation was not observed.
Reduction of silicon recess caused by plasma oxidation during high-density plasma polysilicon gate etching
Authors: Vitale S. A. , Smith B. A.
Published: October 2003

Silicon loss during gate etch from the active region of a traditional complementary metal–oxide–semiconductor transistor is shown to take place through plasma oxidation of the silicon substrate during the overetch step. The plasma oxidation occurs by an ion-enhanced process with an activation energy of only 0.02 eV. This phenomenon is successfully modeled using the traditional Deal–Grove thermal oxidation model, with the inclusion of a depth-dependent reaction rate constant to incorporate the ion-enhancement effect. Plasma oxidation and silicon loss are reduced by using a shorter polysilicon over-etch time, lower source and bias power, lower substrate temperature, and lower O2 flow. A viable polysilicon over-etch process was developed that produced vertical gate profiles while reducing the silicon loss by 32%.
Electrical characteristics of metal–insulator–semiconductor Schottky diodes using a photowashing treatment in AlxGa1−xAs/InGaAs (X=0.75) pseudomorphic high electron mobility transistors
Authors: Han Sang Youn , Choi Kyoung Jin , Lee Jong-Lam , Mun Jae Kyoung , Park Min , Kim Haechon
Published: October 2003

Metal–insulator–semiconductor (MIS) Schottky diodes on Al0.75Ga0.25As/In0.2Ga0.8As pseudomorphic high electron mobility transistors were produced using both photowashing and H2O2 treatments. The Schottky contact on a GaAs layer showed enhancement of the Schottky barrier height of 0.11 eV for the photowashing and 0.05 eV for the H2O2 treatment, respectively. After the photowashing treatment, the Ga oxide (Ga2O3) was dominantly created. In the meanwhile, two types of As oxide (As2O3,As5O2) were mainly produced by the H2O2 treatment, which were distributed uniformly over the GaAs surface. At the same oxide thickness, the formation of the Ga oxide after the photowashing treatment is more effective in enhancement of the Schottky barrier height. This is due to the fact that the Ga oxide was more favorable in the creation of a fixed interface state density, which is known as an origin for increase of the barrier height, compared to the As oxide in the GaAs MIS Schottky diode.
Characterization of CuCl nanocrystals in SiO2 matrix fabricated by inductively coupled plasma-assisted sputtering deposition
Authors: Kurisu Hiroki , Nagoya Kazutaka , Yamada Naoko , Yamamoto Setsuo , Matsuura Mitsuru
Published: October 2003

We have investigated crystal characteristics and optical properties of CuCl nanocrystals embedded in a SiO2 glass matrix, which is fabricated by a novel rf-magnetron sputtering technique combined with an inductively coupled plasma (ICP). The diffraction spots caused by the (111), (220), and (311) planes of the zinc-blende structure of CuCl crystals evidently appear on the electron diffraction patterns under inductively coupled plasma-assisted magnetron-sputtering deposition. Nanoscale particles with the mean particle radius of 4.0 nm are observed in the transmission-electron-microscope images. These results indicate that CuCl nanoparticles are crystallized with a very high quality. This yields optical properties in samples such as the sharp exciton-absorption bands named Z3 and Z1,2. These bands appear with a blueshift, as compared to the bulk-exciton energies caused by the quantum-size effect for the exciton. Only the free-exciton luminescence-band appears without other luminescence bands caused by an impurity.
Electron field emission from boron nitride nanofilm and its application to graphite nanofiber
Authors: Kimura Chiharu , Yamamoto Tomohide , Funakawa Shingo , Hirakawa Masaaki , Murakami Hirohiko , Sugino Takashi
Published: October 2003

Hexagonal polycrystalline boron nitride (BN) films are synthesized on Si substrates by plasma assisted chemical vapor deposition. In the case of the BN films thicker than 20 nm, the turn-on electric field of the electron emission is strongly influenced by the surface roughness rather than the film thickness. On the other hand, in the case of the BN film with a thickness of 8–10 nm, it is found that the turn-on electric field as low as 8.3 V/μm is achieved in spite of the surface of the BN nanofilm being flat as well as the Si substrate. A significant reduction in the effective potential barrier height is suggested. The tunneling controlled field emission is proposed for the BN nanofilm with positive space charge. The BN nanofilm is deposited onto the graphite nanofiber sample. A significant improvement of the field emission characteristics is demonstrated.
Inversion behavior in thermally oxidized p-GaN metal–oxide–semiconductor capacitors
Authors: Nakano Yoshitaka , Kachi Tetsu , Jimbo Takashi
Published: October 2003

The characteristics of thermally oxidized p-GaN metal–oxide–semiconductor (MOS) capacitors fabricated on sapphire substrates have been investigated electrically. 100-nm-thick β-Ga2O3 was grown by thermal dry oxidation of Mg-doped GaN at 880 °C for 5 h. Capacitance–voltage measurements at room temperature show a low interface trap density of ∼1×1010 eV−1 cm−2 and display peculiar behavior that is different from a deep depletion feature. These results indicate some possibilities of surface inversion in thermally grown β-Ga2O3/p-GaN MOS structures without any n+ source regions.
Loss of an MDR Transporter in Compact Stalks of Maize
br2
and Sorghum
dw3
Mutants
Authors: Multani Dilbag S. , Briggs Steven P. , Chamberlin Mark A. , Blakeslee Joshua J. , Murphy Angus S. , Johal Gurmukh S.
Published: October 2003

Agriculturally advantageous reduction in plant height is usually achieved by blocking the action or production of gibberellins. Here, we describe a different dwarfing mechanism found in maize
brachytic2
(
br2
) mutants characterized by compact lower stalk internodes. The height reduction in these plants results from the loss of a P-glycoprotein that modulates polar auxin transport in the maize stalk. The sorghum ortholog of
br2
is
dwarf3
(
dw3
), an unstable mutant of long-standing commercial interest and concern. A direct duplication within the
dw3
gene is responsible for its mutant nature and also for its instability, because it facilitates unequal crossing-over at the locus.
Talin Binding to Integrin ß Tails: A Final Common Step in Integrin Activation
Authors: Tadokoro Seiji , Shattil Sanford J. , Eto Koji , Tai Vera , Liddington Robert C. , de Pereda José M. , Ginsberg Mark H. , Calderwood David A.
Published: October 2003

Control of integrin affinity for ligands (integrin activation) is essential for normal cell adhesion, migration, and assembly of an extracellular matrix. Integrin activation is usually mediated through the integrin β subunit cytoplasmic tail and can be regulated by many different biochemical signaling pathways. We report that specific binding of the cytoskeletal protein talin to integrin β subunit cytoplasmic tails leads to the conformational rearrangements of integrin extracellular domains that increase their affinity. Thus, regulated binding of talin to integrin β tails is a final common element of cellular signaling cascades that control integrin activation.
Evolutionary Discrimination of Mammalian Conserved Non-Genic Sequences (CNGs)
Authors: Dermitzakis Emmanouil T. , Reymond Alexandre , Scamuffa Nathalie , Ucla Catherine , Kirkness Ewen , Rossier Colette , Antonarakis Stylianos E.
Published: October 2003

Analysis of the human and mouse genomes identified an abundance of conserved non-genic sequences (CNGs). The significance and evolutionary depth of their conservation remain unanswered. We have quantified levels and patterns of conservation of 191 CNGs of human chromosome 21 in 14 mammalian species. We found that CNGs are significantly more conserved than protein-coding genes and noncoding RNAS (ncRNAs) within the mammalian class from primates to monotremes to marsupials. The pattern of substitutions in CNGs differed from that seen in protein-coding and ncRNA genes and resembled that of protein-binding regions. About 0.3% to 1% of the human genome corresponds to a previously unknown class of extremely constrained CNGs shared among mammals.
Self-Assembly of Proteins into Designed Networks
Authors: Ringler Philippe , Schulz Georg E.
Published: October 2003

A
C
4
-symmetric tetrameric aldolase was used to produce a quadratic network consisting of the enzyme as a rigid four-way connector and stiff streptavidin rods as spacers. Each aldolase subunit was furnished with a His
6
tag for oriented binding to a planar surface and two tethered biotins for binding streptavidin in an oriented manner. The networks were improved by starting with composite units and also by binding to nickel–nitrilotriacetic acid–lipid monolayers. The mesh was adjustable in 5-nanometer increments. The production of a net with switchable mesh was initiated with the use of a calcium ion–containing β-helix spacer that denatured on calcium ion depletion.
Universality and Critical Behavior at the Mott Transition
Authors: Limelette P. , Georges A. , Jérome D. , Wzietek P. , Metcalf P. , Honig J. M.
Published: October 2003

We report conductivity measurements of Cr-doped V
2
O
3
using a variable pressure technique. The critical behavior of the conductivity near the Mott insulator to metal critical endpoint is investigated in detail as a function of pressure and temperature. The critical exponents are determined, as well as the scaling function associated with the equation of state. The universal properties of a liquid-gas transition are found. This is potentially a generic description of the Mott critical endpoint in correlated electron materials.
Radar Evidence for Liquid Surfaces on Titan
Authors: Campbell Donald B. , Black Gregory J. , Carter Lynn M. , Ostro Steven J.
Published: October 2003

Arecibo radar observations of Titan at 13-centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75% of the subearth locations observed. These specular echoes have properties consistent with those expected for areas of liquid hydrocarbons. Knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of Titan's atmosphere and surface.
Prime Time for the Riemann Hypothesis
Authors: Conrey Brian
Published: October 2003

Prime Obsession
Bernhard Riemann and the Greatest Unsolved Problem in Mathematics. by John Derbyshire. Joseph Henry Press, Washington, DC, 2003. 438 pp. $27.95, C$37.95. ISBN 0-309-08549-7.

Derbyshire interweaves mathematical exposition intended to lead the lay reader to an understanding of the hypothesis and its importance with historical and bibliographical background material.
Structure of the Cytochrome b
6
f Complex of Oxygenic Photosynthesis: Tuning the Cavity
Authors: Kurisu Genji , Zhang Huamin , Smith Janet L. , Cramer William A.
Published: October 2003

The cytochrome b
6
f complex provides the electronic connection between the photosystem I and photosystem II reaction centers of oxygenic photosynthesis and generates a transmembrane electrochemical proton gradient for adenosine triphosphate synthesis. A 3.0 angstrom crystal structure of the dimeric b
6
f complex from the thermophilic cyanobacterium
Mastigocladus laminosus
reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quinone-analog inhibitor, and a novel heme are bound. The core of the b
6
f complex is similar to the analogous respiratory cytochrome bc
1
complex, but the domain arrangement outside the core and the complement of prosthetic groups are strikingly different. The motion of the Rieske iron-sulfur protein extrinsic domain, essential for electron transfer, must also be different in the b
6
f complex.
A Potential Food-Grade Cloning Vector for
Streptococcus thermophilus
That Uses Cadmium Resistance as the Selectable Marker
Authors: Wong Wing Yee , Su Ping , Allison Gwen E. , Liu Chun-Qiang , Dunn Noel W.
Published: October 2003

A potential food-grade cloning vector, pND919, was constructed and transformed into
S. thermophilus
ST3-1, a plasmid-free strain. The vector contains DNAs from two different food-approved organisms,
Streptococcus thermophilus
and
Lactococcus lactis
. The 5.0-kb pND919 is a derivative of the cloning vector pND918 (9.3 kb) and was constructed by deletion of the 4.3-kb region of pND918 which contained DNA from non-food-approved organisms. pND919 carries a heterologous native cadmium resistance selectable marker from
L. lactis
M71 and expresses the Cd
r
phenotype in
S. thermophilus
transformants. With the
S. thermophilus
replicon derived from the shuttle vector pND913, pND919 is able to replicate in the two
S. thermophilus
industrial strains tested, ST3-1 and ST4-1. Its relatively high retention rate in
S. thermophilus
further indicates its usefulness as a potential food-grade cloning vector. To our knowledge, this is the first report of a replicative potential food-grade vector for the industrially important organism
S. thermophilus
.
Engineering
Escherichia coli
for Increased Productivity of Serine-Rich Proteins Based on Proteome Profiling
Authors: Han Mee-Jung , Jeong Ki Jun , Yoo Jong-Shin , Lee Sang Yup
Published: October 2003

Variations in proteome profiles of
Escherichia coli
in response to the overproduction of human leptin, a serine-rich (11.6% of total amino acids) protein, were examined by two-dimensional gel electrophoresis. The levels of heat shock proteins increased, while those of protein elongation factors, 30S ribosomal protein, and some enzymes involved in amino acid biosynthesis decreased, after leptin overproduction. Most notably, the levels of enzymes involved in the biosynthesis of serine family amino acids significantly decreased. Based on this information, we designed a strategy to enhance the leptin productivity by manipulating the
cysK
gene, encoding cysteine synthase A. By coexpression of the
cysK
gene, we were able to increase the cell growth rate by approximately twofold. Also, the specific leptin productivity could be increased by fourfold. In addition, we found that
cysK
coexpression can improve the production of another serine-rich protein, interleukin-12 β chain, suggesting that this strategy may be useful for the production of other serine-rich proteins as well. The approach taken in this study should be useful in designing a strategy for improving recombinant protein production.