bluuebunny/crossref_metadata_2025 huggingface dataset:
Costs, valuation, and long‐term operating effects of global strategic alliances
Authors: Ojah Kalu
Published: October 2006

Using global product design and development as an example of global strategic alliance, I find that successful global strategic competition is still largely a variable cost reduction game as opposed to the recently touted fixed cost amortization game. Further, the firm's cost efficiency is enhanced when its global production initiative is characterized by a high degree of strategic alliances. Importantly, I find that global strategic alliances have both valuation effects and long‐term operating effects, and that both effects are positive functions of the degree of strategic alliances. After controlling for pertinent explanatory factors such as competitive strategy posture, industry concentration, geographic spread of operation, product‐type, and information technology infrastructure of firms, I find that variable cost and production efficiencies remain significant determinants of the valuation effects of global business alliances. Overall, results in this study suggest partnering firms should consider the relative efficiencies of inputs and production technology as effective ways of leveraging the benefits of global strategic alliances.
Does the El Niño–Southern Oscillation control the interhemispheric radiocarbon offset?
Authors: Turney Chris S.M. , Palmer Jonathan G.
Published: October 2006

Since the 1970s it has been recognised that Southern Hemisphere samples have a lower radiocarbon content than contemporaneous material in the Northern Hemisphere. This interhemispheric radiocarbon offset has traditionally been considered to be the result of a greater surface area in the southern ocean and high-latitude deepwater formation. This is despite the fact that the El Niño–Southern Oscillation (ENSO) is known to play a significant role in controlling the interannual variability of atmospheric carbon dioxide by changing the flux of ‘old’ CO2 from the tropical Pacific. Here we demonstrate that over the past millennium, the Southern Hemisphere radiocarbon offset is characterised by a pervasive 80-yr cycle with a step shift in mean values coinciding with the transition from the Medieval Warm Period to the Little Ice Age. The observed changes suggest an ENSO-like role in influencing the interhemispheric radiocarbon difference, most probably modulated by the Interdecadal Pacific Oscillation, and supports a tropical role in forcing centennial-scale global climate change.
Lifetime prevalence and inter-cohort variation in DSM-IV disorders in metropolitan China
Authors: LEE SING , TSANG ADLEY , ZHANG MING-YUAN , HUANG YUE-QIN , HE YAN-LING , LIU ZHAO-RUI , SHEN YU-CUN , KESSLER RONALD C.
Published: October 2006

Background. This is the first study to examine variation across cohorts in lifetime risk of DSM-IV mental disorders in metropolitan China.

Method. Face-to-face household interviews of 2633 adults in Beijing and 2568 adults in Shanghai were conducted from November 2001 to February 2002 using a multi-stage household probability sampling method. The Chinese World Mental Health (WMH) Survey Initiative version of the WHO Composite International Diagnostic Interview (WMH-CIDI) was used for assessment.

Results. Lifetime prevalence of any disorder was 13·2%. Alcohol abuse (4·7%), major depressive disorder (3·5%), and specific phobia (2·6%) were the most common disorders. The median age of onset was later for mood (43 years) than anxiety (17 years) and substance use (25 years) disorders. Compared to observed lifetime prevalence, the projected lifetime risk as of age 75 years increased by 106% for major depressive disorder (7·2%), and was uniformly higher for all disorders. Relative odds of any lifetime disorder were 4·7 in the most recent cohorts (ages 18–34) compared to the eldest cohorts (ages [ges ]65).

Conclusions. The findings of this cross-sectional study tally with the view that rapid socioeconomic changes may bring about increasing incidence of mental disorders in China. However, prospective longitudinal studies are needed to confirm if the increase is real. Because of the huge size of the Chinese population, any increase in projected lifetime risk of mental disorders represents an enormous increase in the number of affected individuals.
Are mangroves worth replanting? The direct economic benefits of a community-based reforestation project
Authors: WALTON MARK E.M. , SAMONTE-TAN GISELLE P.B. , PRIMAVERA JURGENNE H. , EDWARDS-JONES GARETH , LE VAY LEWIS
Published: October 2006

Competition for coastal land use and overexploitation have reduced or degraded mangrove coverage throughout much of their distribution, especially in South-east Asia. Timber production was the initial motivation for early mangrove reforestation projects. More recently, benefits from protection against erosion and extreme weather events and direct improvements in livelihoods and food security are perceived as justifications for such restoration efforts. This study examines the socioeconomic impacts of a community-led reforestation project in the Philippines through a survey of the local fishers. Revenues from mangrove fisheries, tourism and timber result in an annual benefit to the community of US$ 315 ha−1 yr−1. This figure is likely to be considerably more if the contribution of the mangrove to the coastal catch of mangrove-associated species is included. This estimate only includes direct benefits to the community from mangroves, and not intangible benefits such as coastal protection, which paradoxically is perceived by the community as one of the most important functions. More than 90% of all fishers, regardless of where they fished, thought the mangrove provided protection from storms and typhoons and acted as a nursery site and should be protected. Those fishing only in the mangrove perceived more benefits from the mangrove and were prepared to pay more to protect it than those fishing outside. This study concludes that replanting mangroves can have a significant economic impact on the lives of coastal communities. Acknowledgement of the value of replanted mangroves compared with other coastal activities and the benefits they bring to the more economically-vulnerable coastal dwellers should support better informed policy and decision-making with regard to coastal habitat restoration.
Modeling subauroral polarization streams equatorward of the plasmapause footprints
Authors: Pintér B. , Thom S. D. , Balthazor R. , Vo H. , Bailey G. J.
Published: October 2006

We report on a modeling study on the effects of subauroral polarization stream (SAPS) events equatorward of the plasmapause footprints, using the Sheffield Coupled Thermosphere‐Ionosphere‐Plasmasphere (CTIP) model. SAPS events are simulated by imposing a poleward electric field for 2 hours in the premidnight sector between 50° and 60° magnetic latitude. The presence of the SAPS results in a decrease in vertical total electron count and F region ion density, while the height of the F region can rise by up to 100 km. A study of the relative importance of the physical processes finds that the most significant contribution is the temperature increase due to ion‐neutral friction, resulting in increased reaction rates of O+ loss. The recovery time for the SAPS studied is up to 10 hours.
Effects of biomass‐burning‐derived aerosols on precipitation and clouds in the Amazon Basin: a satellite‐based empirical study
Authors: Lin J. C. , Matsui T. , Pielke R. A. , Kummerow C.
Published: October 2006

Biomass burning in the Amazon provides strong input of aerosols into the atmosphere, with potential effects on precipitation, cloud properties, and radiative balance. However, few studies to date have systematically examined these effects at the scale of the Amazon Basin, over an entire burning season, using available data sets. We empirically study the relationships of aerosol optical depth (τa) versus rainfall and cloud properties measured from satellites over the entire Brazilian Amazon during the dry, biomass burning seasons (August–October) of 2000 and 2003. Elevated τa was associated with increased rainfall in both 2000 and 2003. With enhanced τa, cloud cover increased significantly, and cloud top temperature/pressure decreased, suggesting higher cloud tops. The cloud droplet effective radius (Re) exhibited minimal growth with cloud height under background levels of τa, while distinct increases in Re at cloud top temperatures below −10°C, indicative of ice formation, were observed with aerosol loading. Although empirical correlations do not unequivocally establish the causal link from aerosols, these results are consistent with previous observational and modeling studies that pointed to dynamical effects from aerosols that invigorate convection, leading to higher clouds, enhanced cloud cover, and stronger rainfall. We speculate that changes in precipitation and cloud properties associated with aerosol loading observed in this study could have important radiative and hydrological effects on the Amazonian climate system. The accelerated forest burning for agricultural land clearing and the resulting enhancements in aerosols and rainfall may even partially account for the observed positive trend in Amazonian precipitation over the past several decades.
Influences of a shift in North Pacific storm tracks on western North American precipitation under global warming
Authors: Salathé Eric P.
Published: October 2006

Recent global climate model simulations for the IPCC Fourth Assessment report show a realistic North Pacific storm track and Aleutian Low for present‐day climate conditions. Under climate change, the storm track and Aleutian Low move northward and intensify. These changes shift precipitation northward along the Pacific coast of North America. In particular, precipitation is intensified over the Pacific Northwest. Results from a statistical downscaling model suggest that precipitation may become more intense both due to the increased frequency of large‐scale storms and due to changes in the interaction of these storms with the local terrain.
Finite reservoir replica exchange to enhance canonical sampling in rugged energy surfaces
Authors: Li Hongzhi , Li Guohui , Berg Bernd A. , Yang Wei
Published: October 2006

A “finite reservoir” replica exchange method is presented to further enhance sampling upon the regular replica exchange method (REM) in a rugged energy surface. The present method can facilitate important sampling more efficiently by exchanging structures with configurations randomly selected from a finite-sized reservoir; this finite reservoir is pregenerated and updated by a mechanism of replica exchange with neighboring “temperature” simulations. In practice, this proposal revises exchange schedule in REM simulations in order to make productive exchange for conformational “tunneling” more frequent.
Quantum chemical study of electronic and structural properties of retinal and some aromatic analogs
Authors: Savedra Ranylson M. L. , Pinto Melissa F. S. , Trsic Milan
Published: October 2006

The electronic and structural properties of retinal and four analogs were studied using semiempirical, ab initio Hartree-Fock, and density functional theory methods with the aim to evaluate the effects caused by some structural modifications in the ring bound to the polyenic chain and compared with the all-E-trans-retinal molecule. Therefore, some properties such as bond lengths, bond angles, atomic charges derived from electrostatic potential charges from electrostatic potential using grid based method as well as frontier orbitals of the polyenic chain were analyzed. Furthermore, the transition energies of the molecules were also calculated using the Zerner’s intermediate neglect of differential overlap-spectroscopic, time-dependent Hartree-Fock, and time-dependent density functional theory methods. The results indicate that in spite of the structural modifications of retinal derivatives in comparison with all-E-trans-retinal, their properties seem similar. Thus, these molecules may behave similarly to all-E-trans-retinal and possibly be attempted in the search of novel molecular devices.
Evolution of Benjamin-Ono solitons in the presence of weak Zakharov-Kutznetsov lateral dispersion
Authors: Latorre Juan Cristobal , Minzoni A. A. , Vargas C. A. , Smyth Noel F.
Published: October 2006

The effect of weak lateral dispersion of Zakharov-Kutznetsov-type on a Benjamin-Ono solitary wave is studied both asymptotically and numerically. The asymptotic solution is based on an approximate variational solution for the solitary wave, which is then modulated in time through the use of conservation equations. The effect of the dispersive radiation shed as the solitary wave evolves is also included in the modulation equations. It is found that the weak lateral dispersion produces a strongly anisotropic, stable solitary wave which decays algebraically in the direction of propagation, as for the Benjamin-Ono solitary wave, and exponentially in the transverse direction. Moreover, it is found that initial conditions with amplitude above a threshold evolve into solitary waves, while those with amplitude below the threshold evolve as lumps for a short time, then merge into radiation. The modulation equations are found to give a quantitatively accurate description of the evolution of an initial condition into an anisotropic solitary wave. The existence of stable solitary waves is in contrast to previous studies of Benjamin-Ono-type equations subject to the stronger Kadomstev-Petviashvili or Benjamin-Ono-type lateral dispersion, for which the solitary waves either decay or collapse. The present study then completes the catalog of possible behaviors under lateral dispersion.
Dynamical properties of the soft sticky dipole-quadrupole-octupole water model: A molecular dynamics study
Authors: Chowdhuri Snehasis , Tan Ming-Liang , Ichiye Toshiko
Published: October 2006

The dynamical properties of the soft sticky dipole-quadrupole-octupole (SSDQO) water model using SPC/E moments are calculated utilizing molecular dynamics simulations. This new potential for liquid water describes the water-water interactions by a Lennard-Jones term and a sticky potential, which is an approximate moment expansion with point dipole, quadrupole, and octupole moments, and reproduces radial distribution functions of pure liquid water using the moments of SPC/E [Ichiye and Tan, J. Chem. Phys. 124, 134504 (2006)]. The forces and torques of SSDQO water for the dipole-quadrupole, quadrupole-quadrupole, and dipole-octupole interactions are derived here. The simulations are carried out at 298K in the microcanonical ensemble employing the Ewald method for the long-range dipole-dipole interactions. Here, various dynamical properties associated with translational and rotational motions of SSDQO water using the moments of SPC/E (SSDQO:SPC/E) water are compared with the results from SPC/E and also experiment. The self-diffusion coefficient of SSDQO:SPC/E water is found to be in excellent agreement with both SPC/E and experiment whereas the single particle orientational relaxation time for dipole vector is better than SPC/E water but it is somewhat smaller than experiment. The dielectric constant of SSDQO:SPC/E is essentially identical to SPC/E, and both are slightly lower than experiment. Also, molecular dynamics simulations of the SSDQO water model are found to be about twice as fast as three-site models such as SPC/E.
Rotational spectrum of cyanoacetylene solvated with helium atoms
Authors: Topic W. , Jäger W. , Blinov N. , Roy P.-N. , Botti M. , Moroni S.
Published: October 2006

The high resolution microwave spectra of HeN–HCCCN clusters were studied in the size ranges of 1–18 and 25–31. In the absence of an accompanying infrared study, rotational excitation energies were computed by the reptation quantum Monte Carlo method and used to facilitate the search and assignment of R(0) transitions from N>6, as well as R(1) transitions with N>1. The assignments in the range of 25–31 are accurate to ±2 cluster size units, with an essentially certain relative ordering. The rotational transition frequencies decrease with N=1–6 and then show oscillatory behavior for larger cluster sizes, which is now recognized to be a manifestation of the onset and microscopic evolution of superfluidity. For cluster sizes beyond completion of the first solvation shell the rotational frequencies increase significantly above the large-droplet limit. This behavior, common to other linear molecules whose interaction with He features a strong nearly equatorial minimum, is analyzed using path integral Monte Carlo simulations. The He density in the incipient second solvation shell is shown to open a new channel for long permutation cycles, thus increasing the decoupling of the quantum solvent from the rotation of the dopant molecule.
On the current sheet model with κ distribution
Authors: Yoon Peter H. , Lui Anthony T. Y. , Sheldon Robert B.
Published: October 2006

The present paper (re)derives current sheet equilibrium solutions on the basis of the so-called κ distribution functions for the particles. The present work builds upon a recent paper [W.-Z. Fu and L.-N. Hau, Phys. Plasmas 12, 070701 (2005)], where the authors formulated the equilibrium current sheet model with the κ distribution. According to their work, however, the global temperature profile monotonically increases in the asymptotic regime. In the present paper it is shown that the presence of a finite stationary background population of the particles arrests the unlimited increase of the global temperature profile in the asymptotic limit. The present paper further extends the analysis by considering a current sheet model where the electron current is embedded within a thicker ion current layer, and where there exists a weak electrostatic potential drop across the current sheet.
Why are metal foams stable?
Authors: Haibel Astrid , Rack Alexander , Banhart John
Published: October 2006

Although metal foams are becoming accepted engineering materials, the reason for their stability in the liquid state is still under dispute. Liquid metal foams contain solid constituents which according to the existing models stabilize foam films by either modifying the curvature of the liquid/gas (L∕G) interfaces, or by forming particle bridges across metallic films and transmitting repulsive “disjoining” forces mechanically. Using high-resolution synchrotron tomography and a quantitative three-dimensional image analysis the authors show that there is little evidence for such curvature changes or particle bridges. The authors conclude that the main stabilizing action must be due to interactions between neighboring particles attached to L∕G interfaces.
Homogeneous nucleation at high supersaturation and heterogeneous nucleation on microscopic wettable particles: A hybrid thermodynamic∕density-functional theory
Authors: Bykov T. V. , Zeng X. C.
Published: October 2006

Homogeneous nucleation at high supersaturation of vapor and heterogeneous nucleation on microscopic wettable particles are studied on the basis of Lennard-Jones model system. A hybrid classical thermodynamics and density-functional theory (DFT) approach is undertaken to treat the nucleation problems. Local-density approximation and weighted-density approximation are employed within the framework of DFT. Special attention is given to the disjoining pressure of small liquid droplets, which is dependent on the thickness of wetting film and radius of the wettable particle. Different contributions to the disjoining pressure are examined using both analytical estimations and numerical DFT calculation. It is shown that van der Waals interaction results in negative contribution to the disjoining pressure. The presence of wettable particles results in positive contribution to the disjoining pressure, which plays the key role in the heterogeneous nucleation. Several definitions of the surface tension of liquid droplets are discussed. Curvature dependence of the surface tension of small liquid droplets is computed. The important characteristics of nucleation, including the formation free energy of the droplet and nucleation barrier height, are obtained.
Runaway electrons and the evolution of the plasma current in tokamak disruptions
Authors: Smith H. , Helander P. , Eriksson L.-G. , Anderson D. , Lisak M. , Andersson F.
Published: October 2006

After the thermal quench of a tokamak disruption, the plasma current decays and is partly replaced by runaway electrons. A quantitative theory of this process is presented, where the evolution of the toroidal electric field and the plasma current is calculated self-consistently. In large tokamaks most runaways are produced by the secondary (avalanche) mechanism, but the primary (Dreicer) mechanism plays a crucial role in providing a “seed” for the avalanche. As observed experimentally, up to 50%–60% of the plasma current is converted into runaways in the Joint European Torus [P. H. Rebut et al., Nucl. Fusion 25, 1011 (1985)], and the conversion is predicted to be somewhat larger in ITER [R. Aymar et al., Plasma Phys. Controlled Fusion 44, 519 (2002)]. Furthermore, the postdisruption current profile is found to be more peaked than the predisruption current—so much, in fact, that the central current density can increase although the total current falls. It is also found that the runaway current profile easily becomes radially filamented. These results may have implications for the stability of the postdisruption plasma.
Long-term memory contribution as applied to the motion of discrete dynamical systems
Authors: Stanislavsky A. A.
Published: October 2006

We consider the evolution of logistic maps under long-term memory. The memory effects are characterized by one parameter, α. If it equals to zero, any memory is absent. This leads to the ordinary discrete dynamical systems. For α=1 the memory becomes full, and each subsequent state of the corresponding discrete system accumulates all past states with the same weight just as the ordinary integral of first order does in the continuous space. The case with 0<α<1 has the long-term memory effects. The characteristic features are also observed for the fractional integral depending on time, and the parameter α is equivalent to the order index of the fractional integral. We study the evolution of the bifurcation diagram among α=0 and α=0.15. The main result of this work is that the long-term memory effects make difficulties for developing the chaos motion in such logistic maps. The parameter α resembles a governing parameter for the bifurcation diagram. For α>0.15 the memory effects win over chaos.
Identification and properties of the La1 and Lb1 states of pyranine
Authors: Spry D. B. , Goun A. , Bell C. B. , Fayer M. D.
Published: October 2006

The spectroscopic locations of the La1 and Lb1 electronic states of pyranine (1-hydroxy-3,6,8-pyrenetrisulfonic acid, commonly referred to as HPTS), as well as several related compounds, are found using magnetic circular dichroism spectroscopy as well as absorption and fluorescence spectroscopies. These electronic states have been discussed in connection with the photoacid properties of HPTS. Polarization selective fluorescence spectroscopy is used to identify the transition dipole directions of the electronic states of the compounds studied. The issue of the origin for the changes in vibronic structure of HPTS in different solvents is addressed. It is demonstrated that a Brownian oscillator model, in which the strength of the coupling of the electronic states to the solvent changes with solvent, is sufficient to reproduce the trends in the shapes of the vibronic structure.
Development of scanning x-ray fluorescence microscope with spatial resolution of 30nm using Kirkpatrick-Baez mirror optics
Authors: Matsuyama S. , Mimura H. , Yumoto H. , Sano Y. , Yamamura K. , Yabashi M. , Nishino Y. , Tamasaku K. , Ishikawa T. , Yamauchi K.
Published: October 2006

We developed a high-spatial-resolution scanning x-ray fluorescence microscope (SXFM) using Kirkpatrick-Baez mirrors. As a result of two-dimensional focusing tests at BL29XUL of SPring-8, the full width at half maximum of the focused beam was achieved to be 50×30nm2 (V×H) under the best focusing conditions. The measured beam profiles were in good agreement with simulated results. Moreover, beam size was controllable within the wide range of 30–1400nm by changing the virtual source size, although photon flux and size were in a trade-off relationship. To demonstrate SXFM performance, a fine test chart fabricated using focused ion beam system was observed to determine the best spatial resolution. The element distribution inside a logo mark of SPring-8 in the test chart, which has a minimum linewidth of approximately 50–60nm, was visualized with a spatial resolution better than 30nm using the smallest focused x-ray beam.
Ferroelectric domain inversion: The role of humidity
Authors: Dahan D. , Molotskii M. , Rosenman G. , Rosenwaks Y.
Published: October 2006

The authors report on the effect of ambient humidity on domain inversion in ferroelectrics using atomic force microscopy. It is shown that the size of single domains inverted under low humidity in stoichiometric lithium tantalate single crystals is much smaller relative to ambient conditions. These differences are due to the much smaller tip-sample capacitance under low humidity. This phenomenon paves the way for the use of atomic force microscopy to tailor various nanodomain configurations for nonlinear optical applications.
Thermal characterization of submicron polyacrylonitrile fibers based on optical heating and electrical thermal sensing
Authors: Hou Jinbo , Wang Xinwei , Zhang Lijun
Published: October 2006

In this work, the thermal diffusivity of single submicron (∼800nm) polyacrylonitrile (PAN) fibers is characterized using the recently developed optical heating and electrical thermal sensing technique. In the experiment, a thin Au film (approximately in the nanometer range) is coated on the surface of nonconductive PAN fibers. A periodically modulated laser beam is used to irradiate suspended individual fibers to achieve noncontact periodical heating. The periodical temperature response of the sample is monitored by measuring the electrical resistance variation of the thin Au coating. The experimental results for three different synthesized PAN fibers with varying Au coating thickness are presented and discussed.
Thermal conductivity of phase-change material Ge2Sb2Te5
Authors: Lyeo Ho-Ki , Cahill David G. , Lee Bong-Sub , Abelson John R. , Kwon Min-Ho , Kim Ki-Bum , Bishop Stephen G. , Cheong Byung-ki
Published: October 2006

The thermal conductivity of thin films of the phase-change material Ge2Sb2Te5 is measured in the temperature range of 27°C<T<400°C using time-domain thermoreflectance. From the low thermal conductivity of amorphous phase, the conductivity increases irreversibly with increasing temperature and undergoes large changes with phase transformations. Thermal transport in the amorphous and early cubic phases can be described by a random walk of vibrational energy, i.e., the minimum thermal conductivity. In the hexagonal phase, the electronic contribution to the thermal conductivity is larger than the lattice contribution. Crystallization by laser processing produces a cubic phase with a lower thermal conductivity than cubic phases produced by thermal annealing; the authors attribute this difference in conductivity to a larger degree of atomic-scale disorder in films that are crystallized on short time scales.
Influence of surface adsorption in improving ultrashallow junction formation
Authors: Vaidyanathan Ramakrishnan , Seebauer Edmund G. , Graoui Houda , Foad Majeed A.
Published: October 2006

The continual downscaling of silicon devices for integrated circuits requires the formation of transistor (p-n) junctions that are progressively shallower yet incorporate increasing levels of electrically active dopant. In the case of implanted arsenic, the authors show that both goals can be accomplished simultaneously and controllably through the adsorption of small amounts of atomic nitrogen on the Si(100) surface.
Chalcopyrite polymorph for superhard BC2N
Authors: Sun Jian , Zhou Xiang-Feng , Qian Guang-Rui , Chen Jing , Fan Ya-Xian , Wang Hui-Tian , Guo Xiaoju , He Julong , Liu Zhongyuan , Tian Yongjun
Published: October 2006

A chalcopyrite structure is predicted for the potential superhard boron-carbonitride (BC2N), based on ab initio pseudopotential density functional method. Lattice constant, formation energy, bulk modulus, band structure, and electron density of states are calculated. The results show that this compound is a wide gap semiconductor with a direct band gap of about 3.3eV. The calculated Vickers hardness is about 72GPa, which is very close to the measured hardness of c-BC2N (76±4GPa).
Quadrat Analysis of Urban Dispersion: 2. Case Studies of Urban Retail Systems
Authors: Rogers A.
Published: October 2006

This is the second part of a two part paper; the first part reviewed the methodology of quadrat analysis and in this part, two case studies are presented. A brief introduction outlines the spatial structure of retailing in urban areas and it is then demonstrated how compound and generalized distributions offer a variety of models that can be fitted to empirical data about retail spatial structure. The empirical tests use data from Ljubljana, Yugoslavia and San Francisco, California. Conclusions are drawn which relate to the description, analysis and sampling of intra-urban retail spatial dispersions.
Industrial Location and Regional Development—Some Recent Trends in North-West England
Authors: Smith D.M.
Published: October 2006

Deficiencies in local economic structure are very often blamed for the lack of economic growth. The paper is in part an examination of this contention. The concepts of comparative and competitive shift are used to isolate the structural element in relative growth, and an attempt is made to interpret areal variations in competitive shift in the North West Region of England in recent years. The implications of the results for policies of regional development are then considered.
A Kinetic Theory of Traffic Distribution and Similar Problems
Authors: Tomlin S.G.
Published: October 2006

A general approach to traffic distribution problems which provides a means of dealing with both equilibrium states and time-dependent situations is presented. It depends upon a knowledge of certain transition coefficients and points out the fundamental importance of these quantities in the analysis of distribution problems. Although the paper is written as a discussion of traffic distribution it is suggested that the method is of much wider significance and may be valuable for dealing with a variety of social, economic, and biological systems.
Evaluating the Quality of the Residential Environment
Authors: Kain J.F. , Quigley J.M.
Published: October 2006

This paper attempts to measure systematically the extent of blight in a single metropolitan area. Using a sample of individual dwelling units, the paper first describes a method of quantifying some previously neglected aspects of residential quality and demonstrates that they are highly valued by urban households. Secondly, it illustrates the feasibility of generalizing these quality measurements of sample dwellings to all city blocks using widely available explanatory variables. The analysis finds strong inferential evidence of an important, but elusive, relationship among the level of public services provided to particular dwelling units (police protection and schools), measures of residential quality, and the market's valuation of these units. The models described in this paper relate to an important range of urban renewal questions. For example, they can be used to obtain lower bound estimates of the potential benefits of urban renewal programs.
The Perception of Residential Desirability in the Western Region of Nigeria
Authors: Gould P. , Ola D.
Published: October 2006

This paper attempts to extend the investigation of geographic space preferences, focussing particularly on their development and their change from childhood to adulthood, and on the flows of information from which such images are formed. The data used is from Lagos and Western Nigeria. First, the area, the participants, and the questionnaire are explained. Then the space preferences of the area (from five locations) for four age groups from thirteen to twenty-three are described, and the differences between the groups are mapped. The changes over time in these space preferences are discussed, and linked to ideas on the flows of information which help form perception surfaces. The mass media, migration, travel experience, and family membership are discussed. The paper concludes with some hypotheses on the nature of space-learning.
The Visibility of Commuting Costs and Residential Location
Authors: Winger A. R.
Published: October 2006

The purpose of this paper is to show that the failure to perceive the full burden of commuting costs can bias the residential location decision in favor of distant locations. Initially, the argument is developed. Then, Federal Housing Administration data on the site expenditures of families purchasing single-family dwellings in the United States are used as a basis for an empirical investigation, the results of which are shown to be consistent with the argument.
Some Problems of Calibrating the Lowry Model
Authors: Batty M.
Published: October 2006

This paper describes some problems encountered in developing and calibrating a version of the Lowry model in the Central Lancashire and Nottinghamshire-Derbyshire subregions. The formal structure of the model is presented first, and this provides the background to a discussion of the problems involved in estimating the model's parameter values, and in choosing sensitive and meaningful statistics to measure the model's goodness of fit. It is shown that statistics such as R2 measuring the fit of the distributions of population and employment, are extremely insensitive to changes in the parameter values, and that the most sensitive and useful statistic for calibration is the mean trip length. Certain shortcuts in calibrating the model are also suggested by these results and these can be used to get good first approximations of the parameter values.
‘Motorways in London’ and Transport Planning
Authors: Beesley M. E.
Published: October 2006

Motorways in London proposes a substantial reduction in the planned motorway network in London, and its redistribution away from the centre, but it is argued that the book does not justify its case by the measurements presented, and pays too little attention to amenities and compensation. The article is largely concerned with problems for transport planning arising from the book and the official transport and planning documents of 1968 and 1969. The latter's land use and transport model is criticised for its neglect of the economic implications of its ‘suppression’ of trips where networks are overloaded. The model parameters should be required to conform to observed distributions of journey lengths, especially those to work, based on workplace data and recognising the influences, inter alia, of variations in income and levels of skill. A key question in making present models better reflect the long-run interaction between transport and land use is predicting journey-to-work lengths. A model to explain their past change is proposed, based on Census data, measuring the effect of changes in job opportunities, housing demands, and population shifts.
Urban Velocity Fields
Authors: Angel S. , Hyman G.M.
Published: October 2006

The city is not an undifferentiated terrain and travel does not occur along straight-line paths at constant velocities. Variations in travel velocities at different locations bend the minimum time paths away from regions of high congestion. This paper discusses a transformation of the urban plane into a time surface on which distance corresponds to travel time, and describes the construction of minimum paths and isochrones for various velocity fields.

This view of the urban transportation system allows us to discover some of the important features which are often hidden in a network description of the system.
Cost-Benefit Analysis as a Statistical Hypothesis Test: An Example from Urban Transportation
Authors: Ledyard J. O.
Published: October 2006

A method to evaluate the estimated social benefits and costs of many urban transportation decisions is presented, based on the techniques of statistical hypothesis testing. After a slight critique of current practice in cost-benefit analyses, a general equilibrium model is formulated that includes many of the relevant variables and decisions which interact with an urban transportation system. The model is based on individual behavior assumptions (as opposed to macro-behavior) and uses the concept that commodities provide attributes. The significant omissions are mentioned and discussed. It is next shown that if the model is true, then hypotheses involving the Pareto-superiority (and Pareto-optimality) of various decisions with respect to transportation systems imply hypotheses restricting the values of parameters of a single linear equation. This allows the testing (i.e. falsification) of the original hypotheses by using the familiar T and F tests of regression analysis. These tests are based on a single-equation regression only using observations on the rates of use of, the attributes provided by, and the inputs to, the transportation system.

The simplicity of the tests seems to indicate that revisions of the model towards reality would be very productive.
Cybernetic and General-System Approaches to Urban and Regional Research: A Review of the Literature
Authors: McLoughlin J Brian , Webster Judith N
Published: October 2006

Certain theoretical concepts are introduced including the notion of systems, their structure and behaviour; cybernetics and information theory; the dynamics of systems which evolve and adapt their structure, and the maintenance of their organisation; the notion of control. Each concept is illustrated with examples drawn from various disciplines.

The review continues by relating this theoretical framework to systems identified in human-settlement patterns. Contributions by regional scientists are noted, various approaches to urban/regional systems analysis are reviewed, and the specific problems of defining elements, interactions, and an appropriate environment, are discussed.

In conclusion, an attempt is made to identify particular authors and ideas which appear to be the most significant contributions towards the understanding and guidance of change in towns and regions.
A Family of Spatial Interaction Models, and Associated Developments
Authors: Wilson A G
Published: October 2006

This paper shows that the gravity model is not a single model but that there is a whole family of spatial interaction models. The properties of this family are outlined in some detail. Basic concepts of such models can be developed in a variety of ways, and these are illustrated. The paper then outlines a number of other theoretical developments, and is particularly concerned with the disaggregation of such models, with the incorporation of time variables, and with the relation of spatial interaction, to more general, models. Uses of spatial interaction models are outlined briefly and the final section of the paper draws a number of conclusions and presents a summary.
Mental Maps of the City: Suburban Preference Patterns
Authors: Johnston R J
Published: October 2006

Many sets of observations have shown that intra-urban migration is generally oriented outwards, away from the City centre. Two major suggested explanations for this directional bias are Hoyt's concept of the sectoral structuring of socio-economic status residential patterns and Adams's ideas concerning the shape of the mental images of the City which its residents hold. The present paper presents an investigation of the mental maps of some sample respondents in the Christchurch urban area, New Zealand, which asks whether these images are influenced both by the perceived socioeconomic status of the various suburbs and a restricted view of the City. The results are encouraging and suggest that both Hoyt and Adams may have been correct in formulating their ideas.

It is becoming commonplace within urban research to criticise the widely-used models of intra-urban residential patterns as inappropriate. Not all would agree with this, however, so further testing is required. Among the more important aspects needing further investigation are the assumptions on which the models are based, since if these are irrelevant then the validity of the models is extremely unlikely. The aim of the present paper is such an inquiry with reference to Hoyt's sectoral model of the residential patterns of socio-economic status groups.
Dynamic Location-Allocation Systems: Some Basic Planning Strategies
Authors: Scott A J
Published: October 2006

The general location-allocation problem is defined. Then various generalizations of the problem are indicated. The dynamic extension of the location-allocation problem is shown to be of especial interest and significance. Two major approaches to the formulation and analysis of this dynamic problem are discussed. The first approach makes no attempt to anticipate future events and thus leads over the long-run to sub-optimal solutions. The second approach attempts fully to anticipate the future, and is formalized as a dynamic program. This second approach guarantees full optimality over the range of definition of the problem. Some numerical examples are presented.
Statistical Urban Models
Authors: Karlqvist A , Marksjö B
Published: October 2006

The aim of this paper is to analyze some urban models from the viewpoint of statistical theory. The derivations of the gravity model, Clark's formula etc. are given and methods for testing the models are discussed in some detail. Some empirical results are shown, based on data mainly from Stockholm, and some problems concerning computer algorithms are treated in that context.
Fundamental Properties of Löschian Spatial Demand
Authors: Gannon C A
Published: October 2006

Spatial demand is the aggregate demand expressed at a particular location, under given supply conditions, by a set of individual consumers whose locations are dispersed over a geographical market area. Although the concept of spatial demand has played a central role in location and spatial economics since its development by Lösch and his incorporation of it into his model of spatial competitive equilibrium, a comprehensive rigorous characterization of spatial demand does not presently exist. Accordingly, the contribution of this paper is a quite general formulation of spatial demand and a rigorous specification and evaluation of some of its most important properties.

Spatial demand is found to consist of two components: free spatial demand which corresponds to a situation in which the geographic market areas of suppliers do not interact, and competitive spatial demand which corresponds to a situation in which they do. This distinction allows the derivation of conditions for, among other things, the (1) existence of these two components, (2) continuity of the spatial demand function and its first derivative, and (3) convexity or concavity of the spatial demand function. Such properties of spatial demand are basic to an evaluation of the existence, stability, and general nature of spatial competitive equilibrium.
Cost-Benefit Analysis of Information Acquisition in Transportation Planning
Authors: Khan A M
Published: October 2006

This paper presents an analytical methodology, based on the principles of statistical decision theory, for the cost-benefit analysis of information acquisition in transportation planning. Application of this methodology provides guidelines for determining the optimal level of resources to be invested in the collection of information used for planning transport system changes. The rationale of investing resources in transport facilities and the philosophy of evaluating such investments are discussed. The context of the economics of acquiring information to support such analyses is pointed out. Application of the methodology developed to a realistic problem is described. The results of trade-offs between the reduction in social costs of transportation— the benefit, and the cost of information acquisition— the cost, are discussed. Thus, the role of a formal cost-benefit analysis of information acquisition in planning for transport system changes is pointed out.
Perceived Costs
Authors: Neuburger H L I
Published: October 2006

The concept of perceived cost as used in transport economics is described. Three causes of inaccurately perceived cost are analysed in the light of traditional economic theory. The notion of consumers' overheads is introduced to explain how costs may be systematically misperceived, and is incorporated into a modified theory of consumer behaviour. From this theory the method of treating misperceived costs in the economic evaluation of policies is developed. Finally there are some notes on estimation procedure.
The Simulation and Evaluation of Housing Location
Authors: Houghton A G
Published: October 2006

This paper attempts, first by a simple numerical example and then by more rigorous mathematical methods, to investigate the important relationships between supply, demand, distribution, and price in the housing market. A theory of house price is linked to the derivation of home-workplace interaction models. A function for evaluating different distributions is derived and a possible linear programming approach to a marginal stock allocation model is discussed.
Estimation of a Growth Allocation Model for North-West England
Authors: Masser I , Coleman A , Wynn R F
Published: October 2006

A version of the Empiric growth allocation model, which forecasts changes in the proportional shares of the distribution of population and two broad categories of employment, has been developed for North-west England using published sources of information. In spite of estimation problems raised by multicollinearity, and evidence of misspecification for the particular simplified form of the model tested, the results of the study generally support the underlying hypotheses of the model and indicate that it may prove a valuable means of forecasting.
Analytical Properties of Some Multiple-Source Urban Diffusion Models
Authors: Gustafson S-Å , Kortanek K O
Published: October 2006

It is generally required that the concentration of a certain pollutant at any given point ( x, y) shall be below a maximum amount defined by a known function S( x, y). In this paper we analyze different ways of relating the emission rates of polluters with the resultant concentration Q( x, y) by means of various transfer functions. We discuss the analytical properties of the transfer functions which can be derived from various well-known diffusion models. We also discuss a simple instance of optimization models of a type, introduced by Gorr and Kortanek (1970).
A Regional Economic Model for the Assessment of Effects of Air Pollution Abatement
Authors: Lakshmanan T R , Lo Fu-Chen
Published: October 2006

This paper describes the development and demonstration of an operational regional economic model for the assessment of economy-wide effects of air pollution abatement strategies in ninety-one major metropolitan areas in the United States. The model is a cross-sectional Keynesian-type regional macro model that is connected to a national input-output model (1963) via a regional share (location quotient) matrix. The model was used to assess the economic effects of three strategies reflecting the control costs corresponding to the Clean Air Act of 1967, but differing in their incidence of costs among industries, consumers, and government.