bluuebunny/crossref_metadata_2025 huggingface dataset:
Polar mesospheric clouds observed by an iron Boltzmann lidar at Rothera (67.5°S, 68.0°W), Antarctica from 2002 to 2005: Properties and implications
Authors: Chu Xinzhao , Espy Patrick J. , Nott Graeme J. , Diettrich Jan C. , Gardner Chester S.
Published: October 2006

Lidar observations of polar mesospheric clouds (PMC) were made at Rothera, Antarctica, from December 2002 to March 2005. Overall, 128 hours of PMC were detected among the 459 hours of observations, giving a mean occurrence frequency of 27.9%. The mean PMC centroid altitude is 84.12 ± 0.12 km, the mean PMC total backscatter coefficient is 2.34 ± 0.11 × 10−6 sr−1, and the mean layer RMS width is 0.93 ± 0.03 km. The distribution of PMC centroid altitudes over all observations is symmetric (nearly Gaussian), with the most probable altitude (∼84 km) near the center of the distribution. The distribution of PMC brightness is non‐Gaussian and is dominated by weak PMC. The observed PMC altitudes at Rothera support the earlier lidar findings that Southern Hemispheric PMC are on average 1 km higher than corresponding Northern Hemispheric PMC, and higher PMC occur at higher latitudes. Significant interannual and diurnal variations are observed in PMC centroid altitude and brightness. Mean PMC altitude varies more than 1 km from one year to another. In addition, 24‐hour, 12‐hour, and 8‐hour oscillations are clearly shown in PMC centroid altitude and brightness. The altitude distribution of PMC brightness peaks at a nearly constant altitude of 84 km, with weaker PMC found on either side of this altitude. The mean PMC altitudes averaged in brightness bins are anticorrelated with the PMC brightness, where weaker PMC occur at higher altitude and the PMC altitudes are proportional to the logarithm of the PMC brightness.
Compact retarding field energy analyzer for the tokamak ISTTOK boundary plasma
Authors: Nedzelskiy I. S. , Silva C. , Figueiredo H. , Fernandes H. , Varandas C. A. F.
Published: October 2006

The retarding field energy analyzer (RFEA) remains the more reliable diagnostic to measure the ion temperature in the boundary plasmas of magnetic fusion devices. A compact, simple design and inexpensive RFEA has been developed for investigations on the tokamak ISTTOK. It consists of a stainless steel pinhole (with a diameter of 0.6mm), three fine nickel grids with a separation of 1mm, and a collector, all insulated by mica. All the components are placed inside a boron nitride housing with dimensions of 14×14×23mm3. The RFEA has been tested in both ion and electron modes. The conditions of the RFEA operation are discussed, and preliminary measurements of the ion and electron temperature profiles presented.
Photoinduced Rydberg ionization spectroscopy of the B̃ state of benzonitrile cation
Authors: Xu Haifeng , Johnson Philip M. , Sears Trevor J.
Published: October 2006

Photoinduced Rydberg ionization (PIRI) spectra of the second excited electronic state of benzonitrile cation were recorded via the origin and 6a1 and 6b1 vibrational levels of the cation ground electronic state. This B̃←X̃ transition was verified to be a forbidden B22←B12 transition with an origin at 17225cm−1 above the ground ionic state. By the use of vibronic coupling calculations, as well as symmetry analysis and comparison of the PIRI spectra via different ground vibrational levels, a nearly complete assignment of the vibrational structure was made, and the vibrational frequencies of the B̃B22 state of benzonitrile cation were obtained based on the assignments. Comparisons of the experimental spectra with simulations from the vibronic structure calculations are also used to validate the theoretical procedures used in the simulations.
Ordering of azobenzenes by two-photon isomerization
Authors: Ishitobi Hidekazu , Sekkat Zouheir , Kawata Satoshi
Published: October 2006

We report on light induced orientation by two-photon isomerization of azobenzenes in films of polymer. The dynamics of isomerization and orientation by one-photon absorption and two-photon absorption (TPA) are similar, and TPA creates a degree of molecular orientation which is comparable to that achieved by single-photon isomerization, in agreement with the theoretical predictions of two-photon isomeric orientation.
Electric field versus surface alignment in confined films of a diblock copolymer melt
Authors: Kyrylyuk Andriy V. , Fraaije Johannes G. E. M. (Hans)
Published: October 2006

The dynamics of alignment of microstructure in confined films of diblock copolymer melts in the presence of an external electric field was studied numerically. We consider in detail a symmetric diblock copolymer melt, exhibiting a lamellar morphology. The method used is a dynamic mean-field density functional method, derived from the generalized time-dependent Ginzburg-Landau theory. The time evolution of concentration variables and therefore the alignment kinetics of the morphologies are described by a set of stochastic equations of a diffusion form with Gaussian noise. We investigated the effect of an electric field on block copolymers under the assumption that the long-range dipolar interaction induced by the fluctuations of composition pattern is a dominant mechanism of electric-field-induced domain alignment. The interactions with bounding electrode surfaces were taken into account as short-range interactions resulting in an additional term in the free energy of the sample. This term contributes only in the vicinity of the surfaces. The surfaces and the electric field compete with each other and align the microstructure in perpendicular directions. Depending on the ratio between electric field and interfacial interactions, parallel or perpendicular lamellar orientations were observed. The time scale of the electric-field-induced alignment is much larger than the time scale of the surface-induced alignment and microphase separation.
Bulk photochromism in a tungstate-phosphate glass: A new optical memory material?
Authors: Poirier Gaël , Nalin Marcelo , Cescato Lucila , Messaddeq Younes , Ribeiro Sidney J. L.
Published: October 2006

In this work, we present a new photochromic tungstate based glass which have both absorption coefficient and refractive index modified under laser exposure. The photosensitive effect is superficial under ultraviolet (UV) irradiation but occurs in the entire volume of the glass under visible irradiation. The effect can be obtained in any specific point inside the volume using an infrared femtosecond laser. In addition, the photosensitive phenomenon can be erased by specific heat treatment. This glass can be useful to substitute actual data storage supports and is a promising material for 3-dimensional (3D) and holographic optical storage.
End-pumped green and blue vertical external cavity surface emitting laser devices
Authors: Kim Gi Bum , Kim Jun-Youn , Lee Junho , Yoo Jaeryung , Kim Ki-Sung , Lee Sang-Moon , Cho Soohaeng , Lim Seong-Jin , Kim Taek , Park Yongjo
Published: October 2006

The authors report on the development and demonstration of the high power operation of optically end-pumped vertical external cavity surface emitting laser devices emitting at 532 and 460nm. 2.7W green and 1.4W blue output powers were achieved with a good beam quality by intracavity frequency doubling with second harmonic generation crystal. High efficiency and good beam quality are attributed to the enhanced thermal management by the diamond heat spreader directly bonded to the gain region and effective optical pumping by placing the pump laser diode behind the laser structure.
Viscous torque on a sphere under arbitrary rotation
Authors: Lei U. , Yang C. Y. , Wu K. C.
Published: October 2006

The viscous torque on a sphere was derived when the sphere is rotating with an arbitrary time varying angular velocity about a given diameter under the low Reynolds number assumption. The torque is composed of a quasisteady torque and an acceleration torque, which is an integral expression depending on the acceleration history. The acceleration torque can be neglected when the acceleration time scale is sufficiently greater than the viscous time scale, which is appropriate for particles with micron size subject to electrokinetic manipulation.
On the interaction of wind and extreme gravity waves due to modulational instability
Authors: Touboul J. , Kharif C.
Published: October 2006

Freak waves are generated numerically by means of modulational instability. Their interaction with wind is investigated. Wind is modeled as Jeffreys’ sheltering mechanism. Contrary to the case without wind, it is found that wind sustains the maximum of modulation due to the Benjamin-Feir instability. The general kinematic behavior observed for freak waves due to dispersive focusing is recovered here, even if the underlying physics are different in both cases.
Ab Initio Kinetic Modelling in Radical Polymerization: A Paradigm Shift in Reaction Kinetic Analysis
Authors: Coote Michelle L. , Barner-Kowollik Christopher
Published: October 2006

We describe a new rationale to kinetic modelling in which adjustable parameters are avoided through the use of quantum chemistry. This new approach reverses the standard modelling approach in which, having first assumed a kinetic model, it is then fitted to the experimentally determined values of the macroscopic properties (rates, compositions, molecular weight distributions, and so forth) so as to estimate the rate coefficients of the individual reactions. Instead, one still assumes a reaction scheme, but then calculates the rates of the individual reactions using high-level ab initio calculations, and in this way a kinetic model is built that can be used to predict the macroscopic properties of the process from first principles. These can then be compared directly with experiment (for benchmarking purposes) and subsequently be employed to predict the outcome of new chemical processes. In here we illustrate the ab initio modelling technique, using a recent study of initialization in RAFT polymerization as a case study. We also discuss its advantages and possible problems, and highlight some of its potential applications in the radical polymer field.
The Genesis of the Reversible Radical Addition–Fragmentation–Transfer of Thiocarbonylthio Derivatives from the Barton–McCombie Deoxygenation: A Brief Account and Some Mechanistic Observations
Authors: Zard Samir Z.
Published: October 2006

The observations and reasoning leading to the discovery of the degenerative transfer of xanthates and related thiocarbonylthio derivatives are briefly described. A few synthetic applications are presented, and the consequences on the emergence of the RAFT and MADIX polymerization technologies as well as some mechanistic aspects are briefly discussed.
Synthesis of Star Polymers using RAFT Polymerization: What is Possible?
Authors: Barner-Kowollik Christopher , Davis Thomas P. , Stenzel Martina H.
Published: October 2006

Various pathways to generate star polymers using reversible addition–fragmentation transfer (RAFT) are discussed. Similar to other polymerization techniques, star polymers can be generated using arm-first and core-first approaches. Unique to the RAFT process is the subdivision of the core-first approach into the R-group and Z-group approaches, depending on the attachment of the RAFT agent to the multifunctional core. The mechanism of the R- and Z-group approaches are discussed in detail and it is shown that both techniques have to overcome difficulties arising from termination reactions. Termination reactions were found to broaden the molecular weight. However, these side reactions can be limited by careful design of the synthesis. Considerations include RAFT and radical concentration, number of arms, type of RAFT agent and monomer. Despite obvious challenges, the RAFT process is highly versatile, allowing the synthesis of novel polymer architectures such as poly(vinyl acetate) and poly(vinyl pyrrolidone) star polymers.
Controlled Radical Polymerization in Aqueous Dispersed Media
Authors: Save Maud , Guillaneuf Yohann , Gilbert Robert G.
Published: October 2006

Controlled radical polymerization (CRP), sometimes also termed ‘living’ radical polymerization, offers the potential to create a wide range of polymer architectures, and its implementation in aqueous dispersed media (e.g. emulsion polymerization, used on a vast scale industrially) opens the way to large-scale manufacture of products based on this technique. Until recently, implementing CRP in aqueous dispersed media was plagued with problems such as loss of ‘living’ character and loss of colloidal stability. This review examines the basic mechanistic processes in free-radical polymerization in aqueous dispersed media (e.g. emulsion polymerization), and then examines, through this mechanistic understanding, the new techniques that have been developed over the last few years to implement CRP successfully in emulsion polymerizations and related processes. The strategies leading to these successes can thus be understood in terms of the various mechanisms which dominate CRP systems in dispersed media; these mechanisms are sometimes quite different from those in conventional free-radical polymerization in these media.
Beyond General Systems Theory: a Constructivist Perspective
Authors: Low Nicholas
Published: October 2006

Since modem town planning was first promulgated in the nineteenth century it has developed through three phases. Each phase has built on earlier ideas and grown out of the testing of these ideas in practice. The first phase was dominated by the visionary concerned with the physical city; the focus of the second phase was the decision-making structures which create the city. In the third and current phase the town planner has emerged as just one species of government planner. Such a planner must be aware of the complexity of human interaction and must be guided by her own values and political philosophy. General systems theory provided the dominant conceptual framework for the second phase but today we are becoming aware of its insufficiencies. Whether such an all-embracing framework will emerge in the third phase is doubtful. But it is argued here that personal construct theory provides at least a broad theoretical foundation at a high level of abstraction which could give today's planners a better understanding of their role.
Central City Decline and the Provision of Education Services
Authors: Bailey S.J.
Published: October 2006

This article analyses the fiscal consequences of demographic decline for local services in seven British cities. It takes the form of an economist's view of both the ability and willingness of local authorities to reduce provision of the education service in response to falling pupil numbers. A considerable excess of resource inputs is found to exist over a long period, with consequently higher local rate bills and lost opportunities for effective corporate planning.

Some explanation of this maldistribution of local resources is attempted by way of the in-built time lags, departmental-ism, provision for future need, pressure group resistance, political ideology, inertia and the complex multi-disciplinary nature of the subject.
Applicability and Efficiency in a Land Use Plan Design Model: An Input-Output Linear Programming Approach
Authors: Ochitwa Jerome M.
Published: October 2006

The paper proposes a comprehensive land use forecasting model which is to be used in designing land use plans. An attempt is made to develop a model structure which will be more attractive to planners in actually using the model. In addition, and perhaps more importantly, a new teclmiqne is introduced which allocates land based on the fundamental definition of economic efficiency; that is, land is allocated to uses until the marginal value products of all competing uses are equal.
Benefits and Consumption Effects of Public Housing Programs in Belgium: Some Aggregate Results
Authors: DeBorger B.L.
Published: October 2006

In this paper we estimate some aggregate consumption effects and the benefits of public housing programs in Belgium on the basis of a small sample of individual households. Specifying a Stone-Geary utility function defined on housing and other goods we develop estimates of all required inputs to calculate Hick's equivalent variation. We further analyze changes in consumption patterns as well as the distribution of benefits over the sample. Our results provide the first information on the effects of public housing in Belgium derived from micro data.
The Demand for Housing Characteristics in Developing Countries
Authors: Follain James R. , Jimenez Emmanuel
Published: October 2006

This paper develops and estimates an econometric model of the household demand for housing characteristics. The model is estimated using data from five cities and three developing countries. Overall, the procedures employed work well in a wide variety of circumstances.

More specifically, it is found that: (1) Household willingness to pay for living space increases with income but at a less than proportionate rate; (2) Willlingness to pay for living space declines as household size increases; (3) Willingness to pay for several quality measures - structural quality; wall, roof and floor quality - is quite responsive to income.
The Private Rented Sector: A Characteristics Approach
Authors: Whitehead Christine M. E. , Kleinman Mark
Published: October 2006

The paper applies the 'characteristics' approach developed with respect to the labour market in order to examine why the percentage of households who rent privately varies across the country. Regression analysis is used to show that the distribution of private renting is closely related to the distribution of particular household characteristics and that the relationship varies systematically between sub-sectors. Certain local market factors are also shown to be important, particularly with respect to the furnished sector. Within a given urban area the relative size of the rented sector appears to be even more strongly related to household characteristics. Certain implications for spatial policy are then discussed.
Housing and Tax Capitalisation
Authors: Barrow Michael , Robinson Ray
Published: October 2006

This paper examines the effect of the tax treatment of owner occupied housing upon its price, commonly known as the capitalisation effect, and looks at how this has a differential impact upon distinct groups in the housing market. These groups are existing outright owners, existing owners with mortgages, potential purchasers and tenants. It is shown how gains and losses due to the tax treatment of owner occupied housing are distributed amongst these categories, and how they might be realised. Illustrative calculations are presented for each group. The paper shows how the process of capitalisation can exacerbate the unequal treatment of owner-occupiers and tenants and thus presents an argument for the withdrawal of the favourable tax treatment of owner-occupied housing. The problems for the different groups that this change would imply are also discussed.
The Regional Transformation of the American Economy
Authors: Chinitz Benjamin
Published: October 2006

This paper describes the rather remarkable and dramatic changes which have occurred in recent decades in the economic fortunes of the various regions of my country: The USA. I thought of three reasons why you might not be totally bored by my presentation. When I was here in 1965, there was great interest in regional trends within Britain, both from an academic and policy perspective, and I assume this interest lingers on. Second, because my country is so large, both in area and population, it doesn't make much sense to think of it as a unit in international economic relations, whether it be trade or investment. Finally, I see my lecture in part as a report to you on the geographic meanderings of the Pilgrims who left your shores in the 17th century to establish new settlements on the other side of the Atlantic. What I'm going to describe to you is the unfolding of a process which began in Plymouth 365 years ago: the settlement of the American Continent.
Additional Evidence on the Incubator Hypothesis: Detroit, 1970-75
Authors: Kurre James A.
Published: October 2006

In 1959, Hoover and Vernon stated that the central business district of the region was the logical site for a large number of the region's new firms, owing in part to the external economies to be found there. Since then, this incubator hypothesis has been tested by a large number of researchers, with mixed results. This note presents a new test of the hypothesis, using an extensive data base not previously used for this purpose. Considering births in both manufacturing and nonmanufacturing industries over a five-year period in the Detroit metropolitan region, the data fail to support the hypothesis for most industries, although there are some notable exceptions.
Types of Neighbourhood and Home-Based Enterprises: Evidence from Lima, Peru
Authors: Strassmann W. Paul
Published: October 2006

Home-based enterprises are likely to proliferate for decades in developing countries, but their productivity depends on access, cost of space, density of settlement, and other neighbourhood characteristics. Over a thousand households and home enterprises were surveyed in Lima, Peru, in 1980 and 1983, to explain why the frequency and composition of these enterprises varies with seven types of neighbourhood. The enterprises both cause and reflect dwelling and neighbourhood improvement or deterioration. Enterprises are classified by types of product, markets, and the family members in charge. Income and employment effects are stressed. Among the findings was that conventional neighbourhoods had fewer but more lucrative home enterprises than did irregular settlements.
Social and Spatial Disparities in Warsaw in 1978: An Application of Correspondence Analysis to a 'Socialist' City
Authors: Dangschat Jens , Blasius Jorg
Published: October 2006

This paper has two main goals, one is to move towards an explanation of socio-spatial disparities in a 'socialist' city as measured by segregation values for 1978 in Warsaw. The second is to introduce a fruitful hitherto unused technique in urban research, namely correspondence analysis, to describe the relative value of discriminating variables. Socio-spatial disparities in Warsaw are indicated by a typology of planning districts, defined particularly by characteristics of the planning districts' housing stock, but also by socio-demographic characteristics. The unequal spatial distribution of dwellings categorised by construction agencies and by age of building is identified as the main cause of the socio-spatial disparities measured, since the spatial distribution of the residential population by education and age is related to these specific characteristics of the housing stock. The final discussion suggests that the degree of socio-spatial disparity is a consequence of both the actions of the planning authorities, and also unequal access to dwellings.
Whither National Urban Policy in Developing Countries?
Authors: Richardson Harry W.
Published: October 2006

Most attempts to implement national urban policies in developing countries have failed. The causes of failure have been many (infeasible goals, poor implementation, poorly designed policies) but the most difficult problem has been the isolation of national urban policy from national economic planning and from the overall context of macroeconomic and sectoral policies. National policy should not be equated with slowing down urbanization; if so, it will be ineffective in early developing countries and unnecessary in late developing and developed countries. It should not be defined largely as a primacy problem, because the issue is not whether the primate city is too big but rather how will primate city growth be managed. The resource costs of urbanization absorb a very high proportion of the available investment pool, but many of the policy implications are non-spatial (e.g. reducing standards, promoting savings) rather than spatial (e.g. changing the pattern of urbanization). Urban development should be treated as a horizontal slice cutting across almost all sectors rather than as a vertical sector in itself. This may require institutional reorganization at the central government level. Policy innovations should aim for much closer integration between urban development policy and national development planning and give less emphasis to independently conceived spatial policy.
Housing Price Inflation, Family Growth, and the Move from Rented to Owner Occupied Housing
Authors: Rudel Thomas K.
Published: October 2006

This paper uses data from Annual Housing Surveys to investigate the relationship between growth in family size and the move from rented to owner occupied housing in the mid and late 1970s. A series of studies conducted in the 1950s and 1960s established that growth in the size of the family triggered moves from rented to owner occupied housing. Changes in house price inflation during the 1970s may have altered the social and economic conditions associated with a move from rented to owner occupied housing. Log-linear analyses of data from the 1974 and 1978 Annual Housing Surveys indicate that, while growth in the size of a renter's family continued to predict the purchase of owner occupied housing in 1978, the composition of the purchasing group changed significantly between 1974 and 1978, with childless couples increasing and households with children decreasing. The declines in the latter group occurred primarily among poorer households. The implications of these changes for the life cycle - housing cycle model of residential mobility are explored.
Problems of Cost-Recovery in Development Projects: Experience of The Lusaka Squatter Upgrading and Site/Service Project
Authors: Sanyal Biswapriya
Published: October 2006

This paper analyzes the problem of cost-recovery from participants in a major squatter upgrading and site/service project in Lusaka, Zambia. It evaluates the project with respect to five requirements, the fulfillment of which is suggested as necessary for achieving a satisfactory rate of re-payment: (i) the project must be affordable; (ii) the participants must understand the nature of their financial obligation; (iii) the system of collection of payment must be efficient; (iv) incentives and sanctions must be adequate and appropriate; and (v) there must be consistent political support for cost-recovery. The evaluation indicates that though the Lusaka project was affordable by most of the participants, it did not fulfill the four other requirements. The paper concludes with additional guidelines for the design of future projects.
Male/Female Income Distributions, City Size and Urban Characteristics: Canada, 1970-1980
Authors: Soroka Lewis A.
Published: October 2006

While the effects of city size on urban income distributions have been studied, there has been no analysis of the separate effects on male and female income distributions. We assume that urban male and female labour markets are largely segmented. This is supported by the evidence for Canadian cities in 1970 and 1980. Cities with greater male income equality do not necessarily exhibit greater female equality. Further, the variables which contribute to equality for males are different from those for females. An examination of changes in gini coefficients from 1970 to 1980 suggests that the variables which influence inter-urban differences in income equality have little effect on dynamic changes.
Qualitative Response Estimations of the Selling Behaviour in the Swedish Market for Owner-Occupied Houses
Authors: Aguilar Renato , Sandelin Bo
Published: October 2006

The probability that a household will sell its house in a specific year is assumed to be a function of, principally, changes in the characteristics of the household subsequent to purchase. Probit models are estimated from Swedish register data. Leads and lags in the behaviour of the households are introduced. The empirical results indicate that changes in the characteristics of the households do matter. A decrease in income seems to enhance the probability of selling more than an increase in income of the same magnitude. Leads equations exhibit at least as good fit as lags equations. The significance of leads appear to be attached mainly to changes in income while there is a weak indication that lags might be more important concerning the influence of changes in the number of children.
The Distribution of School-Leaver Unemployment Within Scottish Cities
Authors: Garner Catherine , Main Brian G. M. , Raffe David
Published: October 2006

This paper examines the phenomenon of intra-urban unemployment in the context of school-leaver unemployment in Scottish cities. Unlike much of the previous work in this area, the paper avoids the 'ecological fallacy' by utilising data on individual school leavers from the 1981 Scottish School Leavers Survey in conjunction with detailed Small Area Statistics from the 1981 decennial Census. Probit analysis is employed to avoid certain statistical problems. The results indicate that in terms of employment probabilities there is little evidence of any 'area effects' within Scottish cities. In this sense there is one urban labour market in which personal characteristics matter, but where area of residence is of little import. These findings were found to hold in Aberdeen, Dundee, Edinburgh and Glasgow. Within each of these cities the effects of inter-city variations in unemployment rates was found to fail disproportionately on the less qualified and less advantaged young job seekers.
Components of Social Change in Urban Areas
Authors: Congdon Peter , Shepherd John
Published: October 2006

A model for components of social change which distinguishes expected or structural change from positional change is applied to census indices for physically defined urban areas in England. Census profiles are evaluated for groups of urban areas defined by positional change. The model of change used shows a widening of unemployment differentials but convergence in housing stress and car home ownership. At local level, outer city municipal estates undergo positional increases in unemployment, while diffusion of car and home ownership is apparent in middle income owner occupied inner ring towns.
A Synoptic View of Regional Growth and Unemployment: I - The Neoclassical Theory
Authors: McCombie J.S.L.
Published: October 2006

This paper is the first part of a consideration of the implications of the current controversies in macroeconomics for regional growth theory. It is concerned with the neoclassical explanation of disparities in regional growth and unemployment rates. The one-sector and two-sector neoclassical models are surveyed and it is shown how this approach explains differences in productivity growth in terms of the progressive eradication of an initial misallocation of resources (both interregionally and intraregionally). Involuntary unemployment is ascribed to the classical view that real wages are too high. The effect of the spatial diffusion of innovations on productivity growth is also examined.
Upgrading in Chawama, Lusaka: Displacement or Differentiation?
Authors: Rakodi Carole
Published: October 2006

Provision of security of tenure and infrastructure in unauthorised residential areas of Third World cities may render such areas more attractive to higher income households. The danger of displacement is increased if regularisation involves additional costs to residents. The impact of upgrading in a squatter area in Lusaka is evaluated, to ascertain the extent to which it improved living conditions, benefited all residents equally and led to displacement of existing residents. Living conditions had improved for all residents of the area and there was little evidence of displacement or increased rents. However, upgrading had necessitated resettlement of some households in an adjacent overspill area, with a slightly better residential environment and the benefit of larger housing loans, leading to a process of differentiation within the area.
An Analysis of the Economic Impact of the Service Sector on Underemployment in Major Metropolitan Areas in the United States
Authors: Nord Stephen , Phelps John J. , Sheets Robert G.
Published: October 2006

In this study unique measures of underemployment are used to investigate the impact of the service sector on underemployment in a cross-sectional, multivariate analysis of large metropolitan areas in the United States. Underemployment is measured by the inability of labour market participants to earn poverty-level incomes over a full-year (with a separate underemployment measure for each possible cause: low wages; involuntary part-time employment; and, intermittent employment). This study provides evidence that service employment growth will tend to increase underemployment as a result of low wages or involuntary part-time employment. As economic development officials increasingly target service industries as a source of employment growth for metropolitan areas, the results of this study suggest that these same policies that rejuvenate areas and increase tax revenues may raise the concentration of those employed with poverty earnings.
Pedagogic Comment and the Supply of Land for a Particular Use
Authors: Wiltshaw D.G.
Published: October 2006

This article continues the recent debate in Urban Studies on the supply of land. It specifies the analytical framework; corrects misinterpretations of Wiltshaw (1985); emphasises the possibility of the individual possessing a powerful welfare effect and a backward bending land supply curve; and stresses the need to consider the distributions of non-land income and landownership, as well as the form of the utility function, when aggregating supply for a particular use.
Evacuation Intentions of Parents in an Urban Radiological Emergency
Authors: Stern Eliahu
Published: October 2006

As part of the efforts to model the evacuation behaviour of urban residents in the event of a day-time radiological emergency, the present study determines and interprets the extent to which parents of school children rely upon school authorities in evacuating their children away from a danger zone. Two-thirds of parents surveyed in this study distrust organised evacuation and would retrieve their children personally. These parents are usually more mobile. recognising the benefits of nuclear power in general, but at the same time are highly aware of its potential risk to the public. The extent of distrust exceeds similar findings elsewhere. General implications for urban evacuation are discussed, and recommendations for urgent evacuation preparedness of schools are put forward.
National Development and Rural-Urban Policy: Past Experience and New Directions in Kenya
Authors: Evans Hugh Emrys
Published: October 2006

This paper compares earlier and current approaches to rural-urban development in Kenya since its origins in the development Plan of 1970-74. Whereas, earlier, rural-urban development was treated as a self-contained policy area, it is now regarded as an integral component of national development policy. Primary attention is given not so much to the form of the urban system, but to the functioning of it. While the allocation of investments in physical infrastructure remains a key instrument of policy, others include the promotion of small towns serving rural areas - known as 'Rural Trade and Production Centres', the improvement of delivery systems for public services, and incentives for business, particularly small scale enterprises and informal sector activities.
Stayers and Returners in Swedish Rental Housing Improvement
Authors: Wiktorin Marianne
Published: October 2006

Swedish pre-improvement tenants have the right to remain in their flats during modernisation or to return afterwards. One aim of the paper is to assess to what extent these rights are exercised. A second aim is to discuss factors influencing the varying proportions of stayers and returners in different improvement projects. Two-thirds of the tenants move out for good. Building ownership, the extent of improvement and the type of building proved to have a rather large impact on the proportion of stayers. Differences among municipalities and characteristics of the tenants themselves were not as important as had been expected. The same conclusions hold for the proportion or returners. The model tested was less successful in explaining the varying proportion of returners.
Structural Change and Economic Policy in a Declining Metropolitan Region: Implications of the Pittsburgh Experience
Authors: Giarratani Frank , Houston David B.
Published: October 2006

Public-private partnerships can play a valuable role in regional economic policy, but the nature and effectiveness of such alliances depends on the type of problems faced by a region. In the context of decline, partnerships may be oriented to economic renewal and the regeneration of lost economic rents. These objectives may be served while the opportunity costs of policy actions are ignored, and when growth prospects are poor, the risk is ever present that unintended and costly changes in the spatial distribution of activity within a region may occur as a result of government policy actions. Regional policy in the context of decline must focus also on the problems associated with economic adjustment, and partnerships seem ill suited to give full consideration to such objectives.
Structure and Agency in Land and Property Development Processes: Some Ideas for Research
Authors: Healey Patsy , Barrett Susan M.
Published: October 2006

This paper reviews existing approaches to, and research on, land and property development processes. It is argued that while these approaches-institutional analysis, neo-classical location theory and land economics, and Marxist economics-provide useful directions for understanding the development process, they lack the capability to address a fundamental dimension of our understanding of development processes. This is the relation between the way actors behave in deploying resources to realise specific investments, with which much of the real estate literature is concerned, and the broader processes which drive the strategies and interests of the various actors involved. The paper proposes an approach which combines an understanding of structure and agency, focusing on the resources, rules and ideology which actors acknowledge, as a way forward to a richer understanding of land and property development processes. The paper concludes with some key research questions which follow from this perspective.
Security of Tenure, Costly Tenants and Rent Regulation
Authors: Miron J.R.
Published: October 2006

Many jurisdictions give residential tenants legislated packages of rights known generically as 'security of tenure', and some protect tenants further by prohibiting unjustified rent increases. The paper considers the effects of security of tenure on a competitive rental housing market. To illustrate the concepts, the paper describes current security of tenure and rent regulation provisions in the province of Ontario, Canada. A model of rational behaviour by landlords is then presented in which landlords choose simultaneously a rent for a standard lease and the quality of tenant to be accepted. Heterogeneity among landlords and tenants and imperfect information are introduced. The effect of security of tenure legislation on this behaviour is assessed. The paper then considers the difficulty of defining an unjustified rent increase when some tenants are more costly to serve than others and when the landlords have imperfect information about prospective tenants.
The Wage Effects of Residential Location and Commuting Constraints on Employed Married Women
Authors: Madden Janice F. , Chiu Lee-in Chen
Published: October 2006

It has been argued that greater spatial constraints are imposed on the job searches of women workers and that these greater constraints account for some of the gender wage gap. All researchers agree that women commute shorter distances to work than men. In addition, some researchers have argued from indirect evidence that two-earner households give greater weight to husbands' job opportunities when choosing a residential location. In this paper, we use data on two-earner households from the 1980 Public Use Microdata Sample (PUMS) of the US Census for the Detroit and Philadelphia SMSAs to quantify the effects of residential location and of gender differences in commuting behaviour on the gender gap in wages. First, we find that within white households wives encounter relatively greater spatial variation in wages than their husbands but that there is less of a gender difference among black households. Second, we analyse the simultaneous effects of commuting and residential constraints on wages. We find for both cities, and for both blacks and whites, that the gender wage gap is not changed in any significant way by altering women's intrametropolitan residential and job locations.
What Determines Local Authorities' Capital Expenditure on Housing? An Evaluation of Various Models
Authors: Kleinman Mark , Eastall Richard , Roberts Emilie
Published: October 2006

There is a wide variety of theoretical models for explaining expenditure variations across local authorities. These include the demographic approach, agency models, party effect models and incrementalism. In this paper we examine inter-authority variations in housing capital expenditure, testing each of the four models against data for English local authorities for the period 1981/82 and 1986/87. We develop a comprehensive behavioural model, incorporating elements from all the models tested. Finally, we draw conclusions and briefly discuss their implications in the light of proposed changes to British local authority housing finance.
Apartheid and Urban Segregation Levels in South Africa
Authors: Christopher A.J.
Published: October 2006

The policy of apartheid, or racial separation, in South Africa has been one of the most controversial political problems in the latter part of the 20th century. Levels of racial segregation in South African cities have risen markedly in the 20th century as a consequence of legislative programmes, which have also had the result of introducing greater uniformity between the provinces (although the colonial heritage has not been eliminated entirely). The process would appear to have reached its conclusion with a lessening of intent on the part of the government and the survival of some elements of colonial integration. Urban segregation levels have attained remarkably high levels, although the goal of total separation has eluded the White legislators.
Categorical, Multivariate Analysis of Intra-urban Migration
Authors: Eaglstein A. Solomon , Weisberg Jacob
Published: October 2006

A two-step paradigm is employed to analyse intra-urban migration patterns within Israeli towns. In step 1 of the paradigm, census-derived predictor macro-variables descriptive of towns are classified according to the intersection of two nominal dimensions. The three levels of dimension 1 correspond to the three factors emergent from a factor analysis of the predictor variables. These are labelled as representing either economic level, demographic composition or social features of the towns. Dimension 2 was a priori defined as being dichotomous, as it represented each variable's enhancing (a positive β-coefficient) or inhibiting (a negative β-coefficient) effect on intra-urban migration rates. Six cells result from the intersection of the two dimensions. Multivariate regression analysis is carried out within each level of the two dimensions. Regression analysis within the inhibitor level of dimension 1 reveals that four variables inhibited urban residential change: home-ownership, relatively high income, religiosity level of the town and median age of the town's population. These variables are distributed among the three levels of dimension 2. These results partially parallel findings concerning inmigration to Israeli towns that economic variables are crucial to locational decisions. However, with respect to intra-urban moves, economic considerations are less salient. Implications concerning basic urban policy decisions are discussed.
Changing Roles and Positions of Planners
Authors: Albrechts Louis
Published: October 2006

The crisis of the 1970s resulted in major and structural changes in the spatial and politico-economic organisation of society. These changes can be explained by the transition from a Fordist mode of development toward a new, more geographically open and market-based mode of production founded on a growing and all-encompassing flexibility. As planning is not an abstract analytical concept but a concrete socio-historical practice, these changes had a major impact on planning and the planning profession.... That brings us to a new role definition for planners. Some initial ideas are offered as a way of redefining the role. The focus of the paper is on the re-emphasis of the political role of the planner as well as on the technical expertise and the managerial role of the planner.
The Shift from Manufacturing to Services in Sweden
Authors: Fournier Stephen F. , Axelsson Sten
Published: October 2006

Most developed countries have experienced a shift from manufacturing to more service-based economies. In this article we analyse how this shift is affecting Sweden. First, using employment data and information from national input-output tables, we provide evidence of the movement away from manufacturing and the resulting changes in the national industrial mix and in inter-industry linkages. Secondly, using these data along with results from a questionnaire, we examine the growth and changing importance of various service sectors. Finally, using employment information, we show how the changes in manufacturing and service industries are leading to a spatial restructuring of the economy.
Transport Investment and Disadvantaged Regions: UK and European Policies since the 1950s
Authors: Hart Tom
Published: October 2006

This article outlines transport investment policies for older industrial regions with higher unemployment. It examines the motivation behind such policies and compares them with transport policies for other regions. The growth of political and economic competition between problem industrial regions and other regions of disadvantage or growth potential is emphasised. The principal conclusions are that transport policies should not be dominated by the topic of infrastructure investment; that neither inter-regional nor intra-regional transport investment will promote sustained growth in disadvantaged regions if other favourable conditions are lacking; and that a skewing of transport investment towards disadvantaged regions may improve their relative economic position if well integrated with other policies to promote change in the distribution between regions of population and productivity. An increasing role for private sector finance, rail investment and direct road pricing is anticipated within future policies for transport, regional development and environmental improvement.
Producer Services Trade in City Systems: Evidence from Chicago
Authors: Esparza Adrian , Krmenec Andrew J.
Published: October 2006

Recent efforts aimed at understanding the spatial supply and demand of business services have focused on their trade in regional and global settings. Noticeably absent from this research is a clear understanding of the organisation of trade within city systems. This paper demonstrates conceptually that trade flows through a two-tiered organisation of cities. The first involves 'world-class' cities, and the second a hierarchical organisation of cities within the US urban system. These patterns of interaction are analysed empirically using a recent survey of 263 business service establishments located in the Chicago metropolitan region. The survey enables identification of the spatial extent of both supply and demand for five business services. Spatial supply and demand distances are examined more closely via survivor functions. The results indicate that supply and demand distances vary markedly from industry to industry.