bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of excitons and Coulomb beats in a quantum dot molecule
Authors: Degani Marcos H. , Farias Gil A. , Farinas Paulo F.
Published: October 2006

The authors present results for the energy spectrum and the dynamical behavior of excitons in an asymmetric quantum dot molecule. Two main resonances are found by using parameters from GaAs-based systems. Excitonic and binding energies are calculated as functions of an external electric field. They fully explore the dynamics of the exciton, showing the time evolution of both the electron and hole components. The effect of the Coulomb interaction is found to be quite dramatic and responsible for considerably large resonance fields as well as for some underlying beatings found in the main oscillation pattern.
Nonvolatile memory device based on the switching by the all-organic charge transfer complex
Authors: Choi Jin-Sik , Kim Ji-Ho , Kim Song-Ho , Suh Dong Hack
Published: October 2006

The authors have investigated the nonvolatile memory device by the amorphous charge transfer complex of 2, 4, 7-trinitro-9-fluorenone and poly(N-vinylcarbazole) as a spin-coated active layer. The reversible switching can be controlled by the external electric field and the on/off ratio is more than three orders at 1V. The device operation might be interpreted as the generation and the extinction of charged carriers in the active layer through the results of the capacitance and the impedance at each state.
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detector, an infrared detector with reduced dark current and higher operating temperature
Authors: Maimon S. , Wicks G. W.
Published: October 2006

This letter presents a type of infrared detector named the nBn detector. The nBn design essentially eliminates Shockley-Read-Hall generation currents. The result is greatly reduced dark current and noise, compared to other midwave infrared detectors, such as p-n photodiodes. This enables the nBn to operate at background-limited infrared photodetection conditions at significantly higher temperatures than conventional midwave infrared detectors and have greater detectivity near room temperature. The nBn is demonstrated in InAs and InAsSb materials, exhibiting cutoff wavelengths of 3.4 and 4.2μm, respectively.
Effects of the material polarity on the green emission properties of InGaN∕GaN multiple quantum wells
Authors: Lai Yen-Lin , Liu Chuan-Pu , Lin Yung-Hsiang , Lin Ray-Ming , Lyu Dong-Yuan , Peng Zhao-Xiang , Lin Tai-Yuan
Published: October 2006

Green-light-emission InGaN∕GaN multiple quantum wells (MQWs) with different polarities were grown by metal organic chemical vapor deposition. A clear phase separation was observed both in the Ga- and N-polarity samples by high resolution transmission electron microscopy, corresponding to two InGaN-related emissions (In-rich dots and an InGaN matrix) seen in photoluminescence spectra. The dot-related emission in the Ga-polarity MQWs shows stronger carrier localization, as well as a weak influence of defects and temperature insensitivity, when compared to the N-polarity MQWs. In addition, efficient carrier transport, from the low-indium InGaN matrix to high-indium In-rich dots, was observed in the Ga-polarity structure, enhancing the function of quantum-dot structures with Ga polarity, and resulting in a high quantum yield of green light emission.
Enhanced compositional sensitivity in atomic force microscopy by the excitation of the first two flexural modes
Authors: Martinez N. F. , Patil S. , Lozano J. R. , Garcia R.
Published: October 2006

The authors demonstrate that the compositional sensitivity of an atomic force microscope is enhanced by the simultaneous excitation of its first two flexural eigenmodes. The coupling of those modes by the nonlinear probe-surface interactions enables to map compositional changes in several conjugated molecular materials with a phase shift sensitivity that is about one order of magnitude higher than the one achieved in amplitude modulation atomic force microscopy.
Ferromagnetism in Ge1−xCrxTe epilayers grown by molecular beam epitaxy
Authors: Fukuma Y. , Asada H. , Taya T. , Irisa T. , Koyanagi T.
Published: October 2006

IV-VI ferromagnetic semiconductor Ge1−xCrxTe has been grown on BaF2 (111) by molecular beam epitaxy. The ferromagnetism was clearly established by direct magnetization and Hall measurements. The experimental correlation between the anomalous Hall resistivity ρxy and the resistivity ρxx, ρxy∝ρxx1.76, is understood from the semiclassical nature of the charge carrier dynamics, suggesting that the ferromagnetism gives rise to p-d exchange interaction. The Curie temperature increases systematically from the substrate temperature TS of 300to250to200°C and with increasing the Cr composition along with each TS.
Band offset measurements of ZnO∕6H-SiC heterostructure system
Authors: Alivov Ya. I. , Xiao B. , Fan Q. , Morkoç H. , Johnstone D.
Published: October 2006

The conduction band offset of n-ZnO∕n-6H-SiC heterostructures fabricated by rf-sputtered ZnO on commercial n-type 6H-SiC substrates has been measured by a variety of methods. Temperature dependent current-voltage characteristic, photocapacitance, and deep level transient spectroscopy measurements showed the conduction band offsets to be 1.25, 1.1, and 1.22eV, respectively.
Effect of nitrogen incorporation on the thermal stability of sputter deposited lanthanum aluminate dielectrics on Si (100)
Authors: Sivasubramani P. , Kim J. , Kim M. J. , Gnade B. E. , Wallace R. M.
Published: October 2006

The thermal stability of sputter deposited LaAlOx and lanthanum aluminum oxynitride (LaAlON) dielectrics on top of Si (100) was evaluated after 1000°C rapid thermal annealing (RTA). A nitrogen concentration of ∼3at.% in the bulk LaAlON film was found to suppress crystallization as well as metal (lanthanum and aluminum) outdiffusion into the Si (100) substrate after the RTA treatment. These results suggest that film microstructure should be carefully controlled to inhibit impurity diffusion in the conventional gate stack fabrication process.
Enhanced pinning and proliferation of matching effects in a superconducting film with a Penrose array of magnetic dots
Authors: Silhanek A. V. , Gillijns W. , Moshchalkov V. V. , Zhu B. Y. , Moonens J. , Leunissen L. H. A.
Published: October 2006

The vortex dynamics in superconducting films deposited on top of a fivefold Penrose array of magnetic dots is studied by means of transport measurements. The authors show that in the low pinning regime (demagnetized dots) a few periodic and aperiodic matching features coexist. In the strong pinning regime (magnetized dots) a richer structure of unforeseen periodic and aperiodic vortex patterns appear, giving rise to a clear enhancement of the critical current in a broader field range. Possible stable vortex configurations are determined by molecular dynamics simulations.
Gain and lifetime of GaInNAsSb narrow ridge waveguide laser diodes in continuous-wave operation at 1.56μm
Authors: Gupta J. A. , Barrios P. J. , Caballero J. A. , Poitras D. , Aers G. C. , Pakulski G. , Wu X.
Published: October 2006

The continuous-wave (cw) operation of GaInNAsSb lasers at 1560nm is reported. Light-current measurements were made before and after a 100h cw burn in at 20°C, during which a 3×890μm2 device with 72mA initial threshold current and 14mW maximum output power experienced a 15% drop in peak output power. These preliminary lifetime results provide insight into the reliability of GaInNAsSb active regions and reinforce the promise of this material for C-band devices. High-resolution modal gain spectra were extracted from the amplified spontaneous emission spectra acquired after the burn in, providing reliable values for the internal loss, transparency current, and differential gain.
Ambipolar organic field-effect transistors fabricated using a composite of semiconducting polymer and soluble fullerene
Authors: Cho Shinuk , Yuen Jonathan , Kim Jin Young , Lee Kwanghee , Heeger Alan J.
Published: October 2006

Organic field-effect transistors (FETs) with equivalent hole and electron mobilities have been demonstrated. The devices were fabricated using a phase separated mixture of regioregular poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester as the active layer and using aluminum (Al) for the source and drain electrodes. Measurements of the source-drain current versus gate voltage gave an electron mobility of μe=2.0×10−3cm2∕Vs and hole mobility of μh=1.7×10−3cm2∕Vs. The ambipolar FET properties arise from the use of Al electrodes for the source and drain; the contacts between the Al electrodes and the active layer are improved by thermal annealing at elevated temperatures (150°C), thereby enabling balanced injection for both holes and electrons in a single device.
Growth Poles: An Evaluation of Their Propulsive Effect
Authors: Nichols Vida
Published: October 2006

This paper sets out to examine the contention that economic growth will diffuse naturally from a medium-sized growing urban centre to the area immediately surrounding that centre, and eventually beyond into more distant parts of the region. An attempt is made to assess the validity of some existing theoretical and intuitive ideas concerning the spatial diffusion of economic development by means of some simple statistical tests on data for the state of Georgia.
Structuring Urban Transportation Planning Decisions: The Use of Statistical Decision Theory
Authors: Hutchinson B.G.
Published: October 2006

It is argued that there are difficulties in current transportation practice because the existing process does not reflect adequately the context in which urban transportation investments are actually made. Such investments are made sequentially and the planner therefore has the opportunity to monitor the performance of implemented projects and to use this information to reappraise future investments. Decisions are also made under conditions of uncertainty with respect to future demand and costs of construction and operation. This paper demonstrates how some principles of statistical decision theory may be used to structure the sequential nature of transportation investments and to provide for formal treatments of uncertainty and the value of information. A hypothetical example is presented to illustrate the application of the framework developed.
Generating Projects for Urban Research
Authors: Harris B.
Published: October 2006

This paper provides an overview of the author's derivation of the most productive areas for urban research. The first general topic to be considered is the understanding of the urban process, together with the role of that understanding in planning; the second general topic is the problem of generating a limited number of alternative policies which may be considered to be in some sense optimal—in part, the problem of urban design. In each case, the nature of the problems associated with the topic is explored, and a number of suggestions are made for fruitful directions for research.
Optimal Transportation Networks: A Case Study of Highway Systems
Authors: MacKinnon R. D. , Hodgson M. J.
Published: October 2006

This paper outlines some combinatorial approaches to the optimal synthesis of transportation networks. As an example, the inter-urban multi-lane highway network of Southern Ontario and Quebec is studied. A number of network-building algorithms are applied to this situation, and the resulting networks compared to the actual network. Some suggestions for further research are noted.
Time-Lag Effects in Urban Environment Adaptation as a Warning System for Urban Growth Control: An Application to Flanders
Authors: van Naelten M.
Published: October 2006

In this paper we wish to discuss some aspects of a particular system approach in urban planning. An attempt has been made to explain the meaning of the first principal factor (Hotelling, 1933) in the verification of a set of supposed urban characteristics. The same factor model has been used in the subsequent measurement of the degree of urbanity in each municipal territory in Flanders.

In mapping the results we have also attempted to verify some growth and communication theories for the Flanders case. Finally, the basic point of the paper is the detection of time-lag effects which create gaps between the slower development of more rigid environment elements, with which the planner is concerned, and the more quickly adapting elements—a time lag which could indicate urgent planning areas.
Notes on the Design of Operational Models
Authors: Broadbent T A
Published: October 2006

This paper discusses some problems involved in the practical application of mathematical urban models. With reference to some recent applications of a spatial-interaction allocation model, the paper considers questions of dimensionality, separation of variables, system identification, and simple structure principles.
An Operational Urban Development Model of Cheshire
Authors: Barras R , Broadbent T A , Cordey-Hayes M , Massey Doreen B , Robinson Krystyna , Willisf J
Published: October 2006

This paper describes the improvements made to the framework and allocation equations of an operational Lowry model and related aggregate models, describes the concepts used in the data management and development of the computer programs, and outlines the use and, of equal importance, the limitations of the technique.for strategic land use planning. Some preliminary results of the early testing of the model are discussed but the detailed development and testing will be described in subsequent papers.
The Population Density and Rent Distribution Models within a Multicentre Framework
Authors: Papageorgiou G J
Published: October 2006

This paper describes a method used for developing population density and rent distribution models for a hierarchy of centres. Such models may be thought of as describing intraurban or interurban situations. The discussion is confined to the generalization of existing single centre models. It is seen that strong formal links may exist between a single centre model and its multicentre counterpart.
Functional Obsolescence in the Planned Environment
Authors: Nutt B , Sears D
Published: October 2006

This paper introduces the theoretical basis for investigating obsolescence that has resulted from the preliminary stage of an ongoing research programme. A specification for model building is included.
Regional Patterns in Commodity Flows in India
Authors: Lakshmanan P P
Published: October 2006

The paper makes an attempt to delineate regional patterns in commodity flows in India at present and in the foreseeable future. There is heavy concentration of traffic in the north and some concentration in the extreme south of the country, with an east-west grain. The traffic is heaviest nearer the metropolitan centres.

The commodity flows will be larger in the coming years but smaller in relation to the growth in national income, which may lead to a reduction in the proportion of transport investments. Reference is made to the likely emergence of a larger number of smaller regions in India with no vital dependence on any single metropolitan centre as at present. The commodity-mix of the commodity flows in future will change in favour of manufactured goods. This may lead to greater competition between rail and road transport.
The Dependence of Population Distribution on Location Costs
Authors: Amson J C
Published: October 2006

Part of a household's constrained budget is assumed to be comprised of a general cost of location. By using a simple generalisation of Muth's economic theory of the spatial pattern of urban housing, the population density distribution in a plane city is shown to be dependent on the distribution of this generalised cost of location. If housing demand is elastic, then this dependence is shown to be exponential, a conclusion which agrees with a familiar result obtained by maximising the entropy of a population system subject to a cost constraint. If the housing demand is less or more elastic, then the dependence is binomial. Implications of the theory are discussed and illustrations given.
Combinatorial Theory and Boundary Planning
Authors: Dilke S W , Dilke O A W
Published: October 2006

Where areas within a region have been grouped artificially, it is possible to calculate the percentage of probability that adjacent areas will be grouped together. This is worked out for four reconstructions of the effect of Cleisthenes' reform in Attica in the late sixth century B.C. Suggestions are made for the application of the method to modern regions.
Spectral Analysis of Settlement Patterns in Diverse Physical and Economic Environments
Authors: Rayner J N , Golledge R G
Published: October 2006

This paper examines the spatial properties of settlement patterns, using two-dimensional digital spectral analysis, in areas selected for diverse physical and economic environment. A comparison with Christaller geometry is made and discussed.
Stochastic Models of Residential and Geographic Mobility for Heterogeneous Populations
Authors: Ginsberg R B
Published: October 2006

Methods of incorporating population heterogeneity into probability models of intermetropolitan and intrametropolitan mobility are discussed. Two models are described in detail. One allows for heterogeneous transition matrices; methods of estimating the distribution of transition matrices in the population are given. The other focuses on the propensity to move, and allows individuals to change on relevant characteristics over time, thus significantly extending previous models relating various background factors to mobility.
An Incompatibility in Planning for a Steady State and Planning for Maximum Economic Welfare
Authors: Pearce D W
Published: October 2006

The concepts of dynamic ecological equilibrium and optimal externality are defined. The former is frequently advanced by ecologists as an objective of environmental planning. The latter is advanced as a planning objective by economists of the cost—benefit school of thought. It is demonstrated that the two are necessarily incompatible objectives: the former precludes the latter, and vice versa. If the importance of ecological ‘steady states' can be shown, however, it follows from the analysis that the ecological objective is logically prior to the economic objective. The conventional approach to planning for ‘externality correction’ is then misplaced.
An Econometric Technique versus Traditional Techniques for Obtaining Regional Employment Multipliers: A Comparative Study
Authors: Rosen H S , Mathur V K
Published: October 2006

In this paper the authors compare the forecasting ability of an econometric model, which they developed in another paper, with variants of the more traditional technique of the location quotient. The econometric model provides a new method of delineating a region's employment into basic (export) and nonbasic (service) employment. Employment in the Cleveland, Ohio, (SMSA) was divided into these two categories using respectively the econometric model and two variants of the location quotient, one by Tiebout and the other by Thompson. Employment was forecasted within the sample period (1961–66) and outside the period (1967–69). The accuracy of the forecasts was gauged by calculating Theil's inequality coefficients. The results conclusively showed that the econometric method consistently forecasted more accurately than the other techniques, which registered very poor forecasts outside of the sample period.
Spatial Patterns in Suburban Evaluations
Authors: Johnston R J
Published: October 2006

Studies of various types have indicated that residential areas of a city differ in their characteristics, and have suggested that these differences are the bases of residents' choices of where to obtain a home. Although people have been asked why they have made a certain choice, however, no attempts have been made to investigate the number of dimensions to residents' evaluations of suburbs, or the number of criteria on which they rate areas. The present study suggests that there might be five such dimensions, these being amalgams of a large number of terms which could be used to describe an area. The semantic differential technique has been used to test whether these five are relevant to a selection of residents of Christchurch, New Zealand; the analyses suggest that in fact there are probably three interrelated dimensions, and that these three are invariant with area of residence in the city. Although these dimensions of the criteria for evaluation are the same, however, the various suburbs were rated at different levels by groups living in different areas. Apparently both the social and the spatial distance between the respondent's home suburb and that which he is rating are influences on these variations.
The Development of an Urban Interindustry Model: 3. Input—Output Multipliers for Peterborough
Authors: Morrison W I
Published: October 2006

This is the final paper in a three part series published in successive issues of this journal. It discusses further applications of the input—output model developed for Peterborough, and shows first how the technique can be used to assess the effect of increasing sales to final demand by each sector on local income. Then, by using similar methods, the effect of increased sectoral final demand sales on the volume of imports into Peterborough is calculated. Finally some general conclusions on the application of input—output methods at the urban level are drawn.
Poverty, Urban Renewal, and Public Housing in Singapore
Authors: Western J S , Weldon P D , Haung Tan Tsu
Published: October 2006

Singapore is a city state with 80 percent of the population classified as urban. Inadequate and overcrowded housing has led to a massive urban renewal programme. A survey of a sample of residents, predominantly Chinese, who were most likely to be affected by urban renewal led to the identification of two groups: the ‘hard core poor’ and the ‘better off’. Differences between the two groups in activity patterns and attitudes to high-rise flats, appearing around the periphery of the central area, were only marginal, but the hard core poor were much more uncertain about the impact of urban renewal on their life styles. It was concluded that problems of adjustment to urban renewal would be considerably greater for the hard core poor, and, as they comprised the older, less well educated segment of the population with fewer family ties, their future welfare could become a government responsibility.
Preference Rankings on Several Attributes: Applications in Residential Site Selection
Authors: Flowerdew R T N
Published: October 2006

Residential site selection, the process by which a migrant evaluates and chooses among housing opportunities, can be regarded as an example of multi-attribute decision making. If certain simple assumptions are made about the decision, preference rankings of the alternatives can be derived. A classification of these rankings is presented on the basis of preference between various combinations of attributes, and additive utility functions in accordance with the assumptions are noted. Applications of the structure to other kinds of decision are suggested, and extensions to other aspects of residential choice, such as search procedure, are outlined.
An Approach to Urban Modelling and Evaluation a Residential Model: 2. Implicit Prices for Housing Services
Authors: Apps Patricia F
Published: October 2006

This is the second of three papers which describe a model of housing demand, using data from the town of Reading, Berkshire. The first paper sets out the theoretical framework for the model. This second paper documents the results for housing price indices and implicit prices for housing services, or characteristics, such as accessibility to employment and to schools, floor space, age, storey height, and number of garages. The third paper contains results for housing demand equations at three levels of aggregation, and for the real annual costs paid for similar housing in different tenure groups. The research is concerned with ways of obtaining information which is directly relevant to cost-benefit analysis in urban planning, information concerning what are urban services, the relative prices for the services, and the types of environments that produce these services. While the empirical work is restricted by the available data to a cross-section study of demand, the approach might be usefully applied to all types of urban analyses which involve evaluation.
Best-Practice Technology, Technical Leadership, and Regional Economic Development
Authors: Le Heron R B
Published: October 2006

One general response by firms to competitive pressures in technologically dynamic economies is the search within an industry and/or its linked industries for alternative or improved best-practice techniques. The extent of the search for new techniques and subsequent patterns of adoption and adaption are dependent on differential and changing intra- and inter-industry innovative activities. Some plants and firms are more successful at incorporating best-practice technology, achieve higher levels of productivity performance, and attain the status of best-practice enterprises. These enterprises may also assume the role of technical leaders and foster further changes and improvements in the technology of the industry. This article examines first the origins of best-practice technology in an industry, and the nature and evolutionary patterns of technical leadership. This is followed by a consideration of the regional growth impacts and development implications of different evolutionary conditions.
Air Pollution Abatement: Output and Relative Price Effects, a Regional Input—Output Simulation
Authors: Giarratani F
Published: October 2006

This paper uses the direct-cost estimates for air pollution abatement developed for an earlier study (Miernyk and Sears, 1974) to derive technical coefficients for several simulated abatement activities in West Virginia. Output and relative price effects are calculated for particulate matter abatement and two sulfur dioxide abatement alternatives, using a static input-output model.
A Mathematical Model for the Location of Industry in Developing Areas
Authors: Shefer D
Published: October 2006

The major aim of the model developed in this paper is to assist decision makers in identifying the industries which are likely to be attracted to underdeveloped regions as a result of specially devised government policies. The effect of these policies in achieving objectives, such as the reduction of unemployment and underemployment, will differ from industry to industry. Thus it is most important to investigate the production function parameters of each of the industries which are likely to be attracted to these regions, so as to determine to what extent the devised policies will achieve their declared objectives. This paper shows that no single policy can be applied for all industries. It is therefore necessary first to identify the industry and thereupon to devise the proper policy that will advance the overall set of objectives. Finally, we describe in a graphical form in the appendix the gaming process of the on-the-job-training programme which takes place between the trainee and the employer through time.
L'aménagement: Régulation ou Approfondissement Des Contradictions Sociales? Un Exemple: Fos-Sur-Mer et L'aire Métropolitaine Marseillaise
Authors: Bleitrach Danielle , Chenu A
Published: October 2006

Cette étude tente de dégager la signification sociologique de l'aménagement tel qu'il est pratiqué à l'heure actuelle en France. A travers un cas concret, celui de Fos-sur-mer et de l'aire métropolitaine marseillaise, elle analyse la nature des interventions de l'État. Ces interventions, qu'elles portent sur la mise en place d'un appareil de production ou sur le développement de zones urbaines, relèvent de la même logique, celle d'une aide aux secteurs monopolistes.

La planification urbaine est le plus souvent analysée en termes de régulation sociale; notre article se propose de montrer que, loin de relever d'une quelconque régulation, les interventions sélectives de l'État dans le domaine de l'aménagement aboutissent à un approfondissement des contradictions sociales fondamentales.
Dynamic Systems Modelling of the North-West Region: 1. Spatio-Temporal Representation and Identification
Authors: Bennett R J
Published: October 2006

This is the first of four papers which will be published in close sequence in this journal. It examines the major previous attempts at constructing dynamic models of the region, and develops from these an abstract system representation of the spatio–temporal autocorrelation structure of the regional system. This leads to an adaptive spatial-distributed-lag policy model which is applied to the North-west region. The resulting representation is shown to be capable of capturing the temporal and spatial multipliers which govern regional economic evolution. The conditions under which the structure can be identified and its parameters estimated are also discussed.
Environmental Quality and Inflation: A Regional Perspective on the Cost—Push Impact of the 1972 Pure Water Legislation
Authors: Haynes K E , Kleeman W T
Published: October 2006

The United States 1972 ‘Pure Water’ legislation (PL-92-500) requires a national effluent standard such that major industries must apply the “Best Available Treatment” to central waste discharges by 1978, and must reduce their waste discharges to zero by 1983. To meet these standards, industries will require increased capital investments and increased operations and maintenance costs for central equipment for pollution. Since these costs are not distributed evenly among all industries, they will have a differential impact on a regional economy. Furthermore, since technological coefficients in the short-run remain fixed, increased costs attributable to improved environmental quality legislation will affect the consumer in the form of inflated prices. A new approach to the tracing through of these inflationary trends in a regional input-output economy is specified, and applied to the regional economy of Corpus Christi, Texas. Results suggest that if environmental policies, even strict ones, are applied on a regional basis, their inflationary impacts are relatively small.
A Kantian View of the City: A Factorial-Ecology Experiment in Space and Time
Authors: Taylor P J , Parkes D N
Published: October 2006

This paper reports on a factorial-ecology experiment using ‘space—time units’. City space is divided ten ways and time eight ways to produce a set of eighty space—time units. Data is artificially created for these eighty units covering twenty-two variables. From a factor analysis of this data set, seven factors are extracted and interpreted by using the input variables and the space—time framework.
The Design and Evaluation of an Urban Park-and-Ride System: Some Methodological Issues
Authors: Williams H C W L , Sanderson I R , Senior M L
Published: October 2006

This paper presents a summary of findings on the design and evaluation of an urban park-and-ride system. Three main aspects are presented: the construction of mixed-mode demand models; the calculation of user benefits; and the consideration of optimization procedures for the design process. The problems of determining the optimal number, location, parking charges, and sizes of car parks are considered. Discussion is appropriate to car—bus and car—rail interchange.
An Empirical Study of Some Spatial Interaction Models
Authors: Openshaw S
Published: October 2006

This paper attempts to focus attention away from a mathematical and theoretical perspective to one where empirical and statistical aspects can assume greater significance. The need for this change of emphasis is demonstrated by the results of an empirical study of a selection of nine spatial-interaction models. Not only do the theory-based models fail to achieve significantly better levels of performance than some empirically derived models, but both types of model fail to achieve satisfactory levels of descriptive performance. These models are shown to be sensitive to the choice of calibration procedure and various kinds of errors in the constant and independent variables. It is suggested that the use of these models should always be accompanied by estimates of confidence limits, and that there is an urgent need for the development of new model designs which can at least provide accurate descriptions of observed reality.
The Statistical Basis of Decisionmaking in Electoral Districting
Authors: Taylor P J , Gudgin G
Published: October 2006

This paper is concerned with procedures for dividing electorates into constituencies or electoral districts. Two traditions for drawing boundaries are identified, the British procedure of using neutral decisionmakers (Boundary Commissioners), and the American procedure which allows politicians to draw boundaries and thus leads to gerrymandering. If a statistical approach which focuses on the very large number of alternative ways of dividing up an electorate is employed, these two types of decisionmaking can be seen in statistical and political perspective. The most surprising finding of this approach is that in terms of political effects American gerrymanderers and British Boundary Commissioners produce similar types of districting solutions.
A Predictive Model of Urban Stock and Activity: 2. Empirical Development
Authors: Ayeni M A O
Published: October 2006

This is the second of two papers devoted to the theoretical and empirical development of a predictive model of urban stock and activity. The first paper examined a number of concepts and terms in current use and developed the construction of a predictive model. The model is empirically developed and used to answer two types of questions: namely, impact analysis of policy decisions and tracing the trajectory of urban development. The concepts used in the model are validated, thus emphasizing its possible planning uses.
Evaluating English Landscapes—Some Recent Developments
Authors: Clamp P
Published: October 2006

A programme of research to develop two indices to be used as aids in the prediction of public response to issues involving landscape planning, and in particular the routing of new roads through rural areas, is described.

The first index was based on assessments by 272 respondents of the attractiveness of 170 landscapes, presented as panoramas of colour transparencies. This index, which was derived by means of multiple regression statistics, may be used to predict attractiveness scores for other landscapes on the basis of nine measures of visual content.

The second index was derived from assessments by 112 respondents of 63 landscapes, with and without simulated roads. An index based upon landscape attractiveness and the visible extent of the roadway was found to provide an accurate prediction of the change in assessed attractiveness due to the introduction of the road.
The Method of Residues in Urban Modelling
Authors: Batty M , March L
Published: October 2006

This paper seeks to extend the macrostatic approach to urban modelling by treating modelling problems as many-stage processes. Within such a process the early stages are concerned with explaining the relatively trivial characteristics of the phenomena of interest, and the later stages are devoted to explaining more important behavioural issues. Coleman (1964) calls this approach the ‘method of residues’, and its power is first demonstrated here by a reinterpretation of the well-known gravity model. An ad hoc test of the method on the Toronto-centred region serves to emphasise the need for a more formal approach, and thus an analogy between the method and the Bayesian viewpoint is introduced. A method of information minimising, more general but consistently and unambiguously related to the method of entropy maximising, is used to make the formal approach operational, and the method is used to generate an ‘extended’ family of spatial-interaction models. A number of spatial-interaction models are derived, and the paper is concluded by a test of two of these models on the Toronto-centred region.
Spatial Constraint and the Location of Urban Public Facilities
Authors: Hodge D , Gatrell A
Published: October 2006

The effect of urban spatial form, that is, the size, shape, and arrangement of the residential areas of social groups, on the equitable location of public facilities is analyzed. Three measures of spatial form are introduced, and related to the amount of equity in the benefit distributions associated with the location of a single facility, in nineteen different maps. The effect of the size of the service area is also examined. Results indicate that both spatial form and facility size greatly constrain the flexibility of determining equitable facility locations.
A Market-Consumer Model of Residential Property Values: The Airport-Noise—Land-Use Impact Problem
Authors: Haynes K E , Phillips F Y , White G M
Published: October 2006

The paper presents a model of residential property values which is more complete and theoretically grounded than previous regression studies of environmental pollution and land values. By using the distribution model of linear programming, a constrained regression hypothesis is presented which strongly interacts with the theory that generated it. The full use of dual evaluators for estimation purposes is a central feature of the new model, and is an innovative contribution. It is not necessary to observe the purchase price of individual properties, since these (and interval estimates of other offer prices) follow theoretically from the regression results.

A market solution to the housing-allocation problem having been characterized, the consumer's decision problem is considered, and his solution is shown to be in general incompatible with market conditions. This incompatibility is resolved by the use of a multipage or decomposable linear program which incorporates both consumer goals and market conditions. The method of solution of this problem reflects the gain of information that leads to the purchase of a residence by each consumer, and demonstrates the value of the ‘decomposition principle’ in consumer theory. An illustration of the consumer's point of view is developed by using the noise problem of a neighborhood airport.
Residential Neighborhoods as Humane Environments
Authors: Smith C J
Published: October 2006

This paper describes a study of residential neighborhoods. Data from a number of sources were used to identify ten independent dimensions which appeared intuitively meaningful as descriptors of residential settings. The independence of the dimensions indicates that stereotyped characterizations of the ‘urban/rural’ or the ‘affluent/nonaffluent’ type are unable to capture the multidimensional character of residential neighborhoods. It was hypothesized that the dimensions could describe some of the humane characteristics of residential neighborhoods, and a study of well-being in former mental patients lent some support to this hypothesis. Although this was a pilot study and much work remains to be done, the results are encouraging in that they appear to be applicable to planning for the community care of the mentally ill; to the design of humane environments; and as a methodological link in identifying some of the environmental components of psychological well-being.
Towards a Model of Impulse Transmissions for an Urban System
Authors: Bannister G
Published: October 2006

Signal flowgraphs are used for developing short-run impulse-transmission models for urban systems characterized by mutual causation, feedback, and lag structures. The method is flexible in the definition of transmission functions, and a number of techniques, such as transfer functions, differential equations, difference equations and their z-transforms, and linear operators based on two-sector multiplier models, are discussed. The matrix equivalent of the signal flowgraph representation is presented as an input—output matrix, and Mason's rule is used for generating a sensitivity matrix for the system.
Application of an Interindustry Supply Model to Energy Issues
Authors: Giarratani F
Published: October 2006

An interindustry model relating gross output to the availability of primary inputs is used to examine supply linkages associated with national energy production. The results of calculations for US data highlight the importance of extractive energy sectors in intermediate production, and identify supplying sectors that have the potential of restricting energy output. The use of this model as a means to simulate the impact of alternative energy-allocation programmes on gross output is discussed and the results of one simulation are presented.
Determining Ambulance—Hospital Locations for On-Scene and Hospital Services
Authors: Berlin G N , ReVelle C S , Elzinga D J
Published: October 2006

Network models, incorporating several new impedance measures, for the location of ambulances and hospitals are introduced. Although the minimization of average impedance is frequently stated as a criterion in location models, the impedance does not usually embrace more than a single link, such as the time taken from a facility to a demand point. Here the impedance is extended to include not only the primary link between facility and demand but also the link from the point of rescue to the point of ultimate service. The return link between the service point and dispatching station is considered as well. Models for the simultaneous location of ambulance dispatching points and hospitals are framed.
The Effects of Environmental Quality Standards on Pricing Electrical Energy
Authors: Uri N D
Published: October 2006

In this paper the effects of implementing environmental quality standards on the pricing of electrical energy is discussed. In a situation where the maximization of social welfare is the objective, the price, in any period, is set equal to the operating cost plus explicit and implicit environmental-quality costs plus amortization on any new generating capacity. Further, a sufficiently high combination of costs to meet environmental quality standards will result in an earlier retirement of existing capacity than would otherwise have been the case.

In a profit-maximizing situation in which profit is subject to a return-on-investment constraint, the imposition of these standards leads, via the Averch—Johnson effect, to a larger investment in new generating capacity.
Contagion in Neighbourhoods: A Note on Problems of Modelling and Analysis
Authors: Johnston R J
Published: October 2006

The concept of a neighbourhood effect is based on a hypothesised process of contagion, by which people's attitudes and behaviour are influenced by those of others in their locality. If such an effect operates, population redistribution could be a powerful tool for the restructuring of societal attitudes. However, policies must be based on an understanding of the processes, and this requires extensive investigation of their operation. This note looks at ways of modelling and testing for these hypothesised processes in order to achieve an understanding of them.
Parameter Estimation for the Constrained Gravity Model: A Comparison of Six Methods
Authors: Stetzer F
Published: October 2006

Six methods of parameter estimation for the production-constrained gravity model are compared in the context of interurban consumer travel. Monte-Carlo experiments reveal that the nonlinear methods (Batty and Mackie, 1972) are inferior to the linear methods (Nakanishi and Cooper, 1974) when there is specification error present, but that the latter rapidly lose their advantage as sample sizes decrease. Bias in the parameter estimates is a more serious source of error than sampling variation.
Spatial Structure and Spatial Interaction: A Review
Authors: Griffith D A
Published: October 2006

This paper is a review of the literature of that area of spatial interaction which attempts to accommodate the affects of spatial structure. A brief history of this problem is presented, together with criticisms of suggested alternative solutions. Next, spatial interaction in a Christaller K = 3 hierarchy is outlined and its principal components evaluated. Finally, some tentative conclusions as well as several areas for subsequent research are mentioned.
Environmental Ideologies
Authors: O'Riordan T
Published: October 2006

Environmentalism as a social and political movement mirrors the dualities existing within mankind generally in failing to connect desired aims with daily deeds. This is partly because environmentalism has emerged from two contrasting schools of thought, the one nature-orientated, the other centred on technique and mode of organisation. But it is also due to the takeover of much of environmentalist philosophy by groups, both well-meaning and selfish, who either fail to recognise their own hypocrisies or simply shield narrow political aims with the armour of environmental morality. The potential for conflict is therefore great as new patterns of political and economic power emerge but cannot be accommodated by an existing order that finds compromise difficult.
Amenity and Equity: A Review of Local Environmental Pressure Groups in Britain
Authors: Lowe P D
Published: October 2006

The paper discusses the effect, on the distribution of environmental quality and access to facilities, of the growth in Britain of political activity and influence of locality-based, area-oriented groups—the amenity, civic and preservation societies, residents' and tenants' associations, and community action groups—referred to as local environmental pressure groups. After reviewing the growth of organized interest in local environmental issues, one prominent type of local group, amenity societies, is considered in detail, including typical styles of action, resources, ethos, and social composition. It is suggested that the evident effectiveness of many amenity societies may preclude other environmental groups with different social compositions from influencing official planning policies. With growing emphasis on public participation in statutory planning, serious problems of the equity of distribution of amenity and accessibility arise because certain areas and sections of society are not organized to protect their interests in the environment; certain sections of the community lack the available resources to sustain effective pressure group activity; and some local political cultures are unreceptive to group activity. The problems of political equity, the representativeness of local environmental groups, variations in potential political efficacy between existing groups, and the failure of certain interests to achieve political expression are each considered in detail.

It is concluded that the medium of political organization will magnify the differences and inequalities of the social structure, and that the activities of local environmental pressure groups will tend to accentuate existing disparities between the favoured environments of the powerful and wealthy and the degraded environments of the deprived.
A Note on Civic State Equations
Authors: Amson J C
Published: October 2006

A more general relationship (‘state equation’) between housing costs and population density is deduced by an improved version of an earlier argument (Amson, 1972a). The relative importance of land factors in housing production, and the consumer's personal housing-cost index, can be used as parameters in the relationship.
Measuring the External Effects of Public Programs
Authors: Dear M , Fincher Ruth , Currie Lise
Published: October 2006

This paper reports attempts to measure systematically the external effects of public programs. Specifically the paper focuses upon those intangible (that is, nonquantitative) externalities, which are such a potent force in generating community opposition. The general concept of external effects is reviewed, in order to clarify the requirements of any systematic analysis. Two approaches, one using multidimensional scaling, the other using the semantic differential technique, are described and demonstrated in a simple empirical example. These techniques should facilitate the development of cross-sectional and aggregate analyses of conflict situations.