bluuebunny/crossref_metadata_2025 huggingface dataset:
Relaxation scenarios in a mixture of large and small spheres: Dependence on the size disparity
Authors: Moreno Angel J. , Colmenero Juan
Published: October 2006

We present a computational investigation on the slow dynamics of a mixture of large and small soft spheres. By varying the size disparity at a moderate fixed composition different relaxation scenarios are observed for the small particles. For small disparity density-density correlators exhibit moderate stretching. Only small quantitative differences are observed between dynamic features for large and small particles. On the contrary, large disparity induces a clear time scale separation between the large and small particles. Density-density correlators for the small particles become extremely stretched and display logarithmic relaxation by properly tuning the temperature or the wave vector. Self-correlators decay much faster than density-density correlators. For very large size disparity, a complete separation between self- and collective dynamics is observed for the small particles. Self-correlators decay to zero at temperatures where density-density correlations are frozen. The dynamic picture obtained by varying the size disparity resembles features associated with mode coupling transition lines of the types B and A at, respectively, small and very large size disparities. Both lines might merge, at some intermediate disparity, at a higher-order point, to which logarithmic relaxation would be associated. This picture resembles predictions of a recent mode coupling theory for fluids confined in matrices with interconnected voids [V. Krakoviack, Phys. Rev. Lett. 94, 065703 (2005)].
Room temperature low-field colossal magnetoresistance in La0.7Sr0.3MnO3
Authors: Imamori S. , Tokunaga M. , Hakuta S. , Tamegai T.
Published: October 2006

It is found that La0.7Sr0.3MnO3 crystal shows hysteretic nonlinear V-I characteristics at high currents. The authors have reproduced such a behavior by using a simple thermal equation. Utilizing magnetic field dependence of the V-I curves, magnetoresistance ratio of R(0Oe)∕R(2.8kOe)=230% is realized at room temperature in the presence of bias currents.
Cumulative contributions of 3s–np (n⩾3) transitions in comparing O atom densities in low-pressure Ar–O2 and He–O2 glow discharges
Authors: Khan Mohammad Aslam , Al-Jalal Abdulaziz M.
Published: October 2006

Many-fold enhancements in the population densities of O atoms in low-pressure glow discharges in Ar–O2 and He–O2 compared with the discharge in pure O2 have been reported in recent years. In some reports, the 3sS3,5–3pP3,5 transitions of O atoms around 844.6 or 777.2nm are considered in estimating the density of atomic oxygen. The authors’ results demonstrate that the contributions of other possible transitions such as 3sS3,5–npP3,5 (n>3) directly feeding the lower 3sS3,5 levels are also significant and should be included for a better estimate of O atom densities.
Synthesis and thermoelectric properties of type-I clathrate Ge30P16Te8
Authors: Kishimoto Kengo , Akai Koji , Muraoka Noriaki , Koyanagi Tsuyoshi , Matsuura Mitsuru
Published: October 2006

The tellurium-containing cationic type-I clathrate Ge30P16Te8 was synthesized and its thermoelectric properties were investigated. This clathrate showed a p-type conductivity, while most of the clathrates are n type. The Ge30P16Te8 clathrate had a band gap energy of 0.62eV and a room temperature thermal conductivity of 9mWcm−1K−1, which is as low as those of germanium clathrates such as anionic Sr8Ga16Ge30 and cationic Ge38Sb8I8. The electronic structure of the Ge30P16Te8 clathrate was also calculated using an ab initio method.
Characteristics of an organic light-emitting diode utilizing a phosphorescent, shallow hole trap
Authors: Campbell I. H. , Crone B. K.
Published: October 2006

The authors demonstrate the effects of incorporating a phosphorescent, shallow hole trap in an organic light-emitting diode. They present device properties as a function of trap concentration including electron only, hole only, and bipolar current-voltage (I-V) characteristics, electroluminescence (EL) and photoluminescence spectra, and diode quantum efficiency. They specifically considered poly(9,9-dioctylfluorene) doped with an Ir phosphor. Built-in potential and I-V measurements were used to determine that the phosphor is a shallow trap. The EL spectrum is dominated by phosphor emission for concentrations above 0.1wt%. The effects of incorporating the phosphor are shown to be consistent with quasiequilibrium statistics.
Dopant distribution in the recrystallization transient at the maximum melt depth induced by laser annealing
Authors: Ong K. K. , Pey K. L. , Lee P. S. , Wee A. T. S. , Wang X. C. , Chong Y. F.
Published: October 2006

Pileup of boron atoms near the maximum melt depth in bulk silicon and silicon-on-insulator (SOI) substrates upon laser annealing (LA) was studied. The results show that boron atoms accumulate near the maximum melt depth in shallow melting and increases with increasing laser pulses. The pileup is found to be related to the recrystallization behavior of the melted silicon during LA and occurs at a recrystallization transient, RT0, of about 10nm from the maximum melt depth in both SOI and bulk silicon substrates. An abrupt recrystallization process in preamorphized silicon, on the other hand, suppresses the formation of the boron pileup during LA.
Periodic chains of gold nanoparticles and the role of oxygen during the growth of silicon nanowires
Authors: Kolb Florian M. , Berger Andreas , Hofmeister Herbert , Pippel Eckhard , Gösele Ulrich , Zacharias Margit
Published: October 2006

The introduction of oxygen during silicon monoxide–vapor liquid solid growth of silicon nanowires causes a shift in silicon suboxide stoichiometry resulting in an increased formation of silicon dioxide at the nanowire surface. This leads to instabilities of the usual cylindrical nanowire core-shell structure, where the liquid gold/silicon alloy droplet at the nanowire tip is incorporated inside a silicon dioxide nanowire to form a periodic array of nanoparticles. The structure and the composition of the resulting nanostructure are investigated using transmission electron microscopy. The influence of the oxygen is investigated experimentally and supports the authors’ model of the formation mechanism.
Comment on “Low resistivity p-ZnO films fabricated by sol-gel spin coating” [Appl. Phys. Lett. 88, 251116 (2006)]
Authors: Wan Q.
Published: October 2006

In a recent letter, Cao et al. [Appl. Phys. Lett. 88, 251116 (2006)] reported the growth of In+N codoped p-type ZnO films with a low resistivity of 1.58×10−1Ωcm by a simple sol-gel spin coating method. Unfortunately, this low resistivity value is doubtful based on Hall effect measurement analysis. If the values of carrier concentration and Hall mobility are correct in their experiment, the resistivity value should be 10.62Ωcm, but not 1.58×10−1Ωcm.
Electrical properties of AlGaN∕GaN heterostructures grown on vicinal sapphire (0001) substrates by molecular beam epitaxy
Authors: Shen X. Q. , Okumura H. , Furuta K. , Nakamura N.
Published: October 2006

Electrical properties of AlGaN∕GaN heterostructures grown on vicinal sapphire (0001) substrates by molecular beam epitaxy (MBE) are investigated. It is found that electrical properties of the two-dimensional electron gas (2DEG) in the heterostructures grown on 2.0°-off vicinal substrates are superior to those grown on the 0.5°-off vicinal substrates. Anisotropic phenomenon of the 2DEG mobility in the heterostructures grown on 2.0°-off substrates is demonstrated, which strongly relates to the macrostep structures on the surface. The 2DEG mobility as high as 2018cm2∕Vs is obtained at the room temperature from the authors’ all-MBE-grown sample measured in the direction parallel to the macrostep. It is suggested that the direction effect should be taken into account when designing the device structure.
Experimental determination of strain-free Raman frequencies and deformation potentials for the E2 high and A1(LO) modes in hexagonal InN
Authors: Wang Xinqiang , Che Song-Bek , Ishitani Yoshihiro , Yoshikawa Akihiko
Published: October 2006

Strain-free Raman frequencies of the E2 high and A1(LO) modes of hexagonal InN are determined to be 490.1±0.2 and 585.4±0.4cm−1 by Raman measurements on a freestanding InN film grown by molecular beam epitaxy. The strain-free Raman frequencies are further confirmed by linear fits to Raman frequencies of the E2 and A1(LO) modes of InN epilayers under different biaxial strains. Raman linear biaxial stress coefficients for the E2 and A1(LO) modes of InN are obtained with values of 9.0±0.8 and 8.4±0.8cm−1∕GPa. The phonon deformation potentials are also obtained by using sets of available stiffness constants of hexagonal InN.
Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes
Authors: Haranath D. , Chander Harish , Sharma Pooja , Singh Sukhvir
Published: October 2006

Results pertaining to the development of highly dispersible stand-alone particles of Ce3+-doped Y3Al5O12 nanophosphor and their luminescence are presented. The yellow light-emitting nanophosphor was produced as a result of a single-step auto-combustion process, which requires no auxiliary annealing treatments prior to any practical application. The structure, photoluminescence, and chromaticity of the powder nanophosphor samples with the compositions Y(3−x)Al5O12:xCe3+ (x=0.01–1) are featured in the letter. The nanophosphor absorbs light efficiently in the visible region of 400–500nm, and shows single broadband emission peaking at ∼560nm. The luminescence yield is almost analogous to the samples made from other conventional methods. Hence, it could be an apt candidate for generating white light when coupled to a blue light-emitting diode (λem=450nm).
Surface electronic structure of HfO2 resolved with low energy ion spectroscopy
Authors: Zenkevich Andrei , Lebedinskii Yuri , Pushkin Mikhail , Nevolin Vladimir
Published: October 2006

Low energy ion scattering spectroscopy has been applied to probe surface electronic structure of HfO2 and appeared sensitive to the presence of the band gap in the outmost surface layer. We demonstrate that HfO2 has a clear signature in He+ spectra that is remarkably different from those of metallic Hf and HfSi2. The observed effect is described in terms of He+ inelastic energy loss due to electronic excitations during impact, and is used to monitor in situ the evolution of HfO2 surface electronic structure during vacuum annealing. Our data provide evidence for effective “metallization” of HfO2 surface under heating to T>600°C.
Tunnel-assisted manipulation of intersubband polaritons in asymmetric coupled quantum wells
Authors: Anappara Aji A. , Tredicucci Alessandro , Beltram Fabio , Biasiol Giorgio , Sorba Lucia
Published: October 2006

The authors report the external control of the polariton ground state by manipulating the coupling between the intersubband transition and the photonic mode of a GaAs∕AlGaAs microcavity. The vacuum-field Rabi splitting is varied by means of charge transfer between the energetically-aligned ground subbands of asymmetric tunnel-coupled quantum wells. The authors propose the use of this structure concept for implementing ultrafast modulation of intersubband polaritons.
Z-shaped magnetostrictive patch for efficient transduction of a torsional wave mode in a cylindrical waveguide
Authors: Park Chan Il , Cho Seung Hyun , Kim Yoon Young
Published: October 2006

An earlier investigation [C. I. Park et al., Appl. Phys. Lett. 87, 224105 (2005)] using topology optimization showed that if V-shaped yokes are attached to magnetostrictive strips obliquely bonded on the surface of a cylindrical waveguide, the transduction efficiency of ultrasonic torsional waves can be substantially increased. However, some unwanted wave modes are also generated unless some damping treatment is applied. This investigation shows that if the strips are reconfigured as Z-shaped patches, the transduction efficiency gained by the optimization technique can be maintained without the generation of unwanted modes. By experiments using the Z-shaped patches, the transduction characteristics including the frequency characteristics of an ultrasonic torsional wave are also investigated.
Nondispersive hole transport in a polyfluorene copolymer with a mobility of 0.01cm2V−1s−1
Authors: Fong H. H. , Papadimitratos Alexios , Malliaras George G.
Published: October 2006

The hole mobility in the fluorene copolymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)) diphenylamine)] (TFB) was measured using the time-of-flight technique. Transport was found to be nondispersive throughout the temperature range between 220 and 350K, indicating the absence of intrinsic traps in this material. At room temperature, TFB shows a hole mobility of 0.01cm2V−1s−1, with a weak field dependence. The hole mobility is independent of sample thickness in the range between 0.9 and 6.4μm. These results are in agreement with a narrow transport manifold, with a width of 65.9±0.5meV.
Noncontact friction force microscopy based on quartz tuning fork sensors
Authors: Labardi M. , Allegrini M.
Published: October 2006

Noncontact friction force microscopy (NC-FFM) measures the damping of the resonant oscillation of an atomic force microscope (AFM) tip that vibrates parallel to the sample surface at a controlled distance. By exploiting the two fundamental orthogonal vibration modes of a quartz tuning fork, such technique can be realized by all-piezoelectric sensing by simultaneously employing an AFM noncontact mode for distance control. The low noncontact-mode vibration amplitude used increases the effective interaction time for shear measurement. Application to polymeric samples shows that the dissipation contrast of NC-FFM is higher than that of the corresponding noncontact-mode phase imaging.
Anisotropic conduction induced by current processing in the La0.8Ca0.2MnO3 film
Authors: Xie Y. W. , Sun J. R. , Wang D. J. , Liang S. , Lü W. M. , Shen B. G.
Published: October 2006

Effects of current processing have been experimentally studied for the La0.8Ca0.2MnO3 film. An anisotropic conduction is observed when the film is processed by a current of the density of ∼2.4×105A∕cm2. Difference between the resistances in the direction of the processing current and the reverse direction can be as high as 10 000%. Different from the original film, which exhibits a metal-to-insulator transition at ∼214K, the sample becomes insulating below 300K under low voltage bias and undergoes a metallic transition at very different temperatures in the two directions when the voltage bias is high enough. These features remain after reordering the electrodes, which reveals the intrinsic origin of the anisotropy, instead of interfacial barrier due to current processing.
Effects of blending with fluorescing molecules on the dynamics of the β, α, and α′ relaxations observed in poly(methyl methacrylate)
Authors: Kalogeras Ioannis M. , Pallikari Fotini , Vassilikou-Dova Aglaia , Neagu Eugen R.
Published: October 2006

Perturbations in typical dielectric or calorimetric features of the molecular relaxation dynamics in amorphous poly(methyl methacrylate) and two blends with a neutral/apolar brominated perylene dye were analyzed to explore guest-host nanoscale interactions and their role on lasing properties. Aside from a gradual increase of the relaxation strength Δεβ (plasticization), the local β relaxation is nearly independent of the presence of dye. By contrast, segmental dynamics are moderately hampered: both the dielectric (Tα) and calorimetric (Tg) estimates of the glass transition temperature rise with increasing dye content, probably as a result of modifications in the free volume (antiplasticization). Analogous shifts are observed in the peak temperature of the space-charge relaxation (Tρ) and the α′ (liquid-liquid) transition (TLL), with Tρ∕Tα=1.04±0.01 and TLL∕Tα=1.10±0.01.
Valence Bond Formulations of Mechanisms for the Formation and Decomposition of N2O5
Authors: Harcourt Richard D. , Klapötke Thomas M.
Published: October 2006

Environmental Context. N2O5 is an important nitrogen reservoir in polar stratospheric clouds found in Antarctica and involved with the ozone hole. Here we provide valence bond representations for the gas-phase formation and decomposition of this molecule.
Abstract. Qualitative valence bond considerations are used to suggest how electronic reorganization could proceed for (a) the formation of N2O5 via the reactions NO2 + O3 → NO3 + O2, and NO2 + NO3 → N2O5, and (b) the thermal decomposition of N2O5 via the following sets of reactions: (i) N2O5 → NO2 + NO3, 2NO3 → O2NOONO2 →2NO2 + O2; (ii) NO2 + NO3 → ONOONO2 → NO + O2 + NO2, NO + NO3 → 2NO2. Increased-valence structures, which possess one-electron bonds and fractional electron-pair bonds as well as ‘normal’ electron-pair bonds, are used to represent the electronic structures of the molecules.
Genome scan for cis-regulatory DNA motifs associated with social behavior in honey bees
Authors: Sinha Saurabh , Ling Xu , Whitfield Charles W. , Zhai Chengxiang , Robinson Gene E.
Published: October 2006

Honey bees (
Apis mellifera
) undergo an age-related, socially regulated transition from working in the hive to foraging, which is associated with changes in the expression of thousands of genes in the brain. To begin to study the cis-regulatory code underlying this massive social regulation of gene expression, we used the newly sequenced honey bee genome to scan the promoter regions of eight sets of behaviorally related genes differentially expressed in the brain in the context of division of labor among worker bees, for 41 cis-regulatory motifs previously characterized in
Drosophila melanogaster
. Binding sites for the transcription factors Hairy, GAGA, Adf1, Cf1, Snail, and Dri, known to function in nervous system development, olfactory learning, or hormone binding in
Drosophila
, were significantly associated with one or more gene sets. The presence of some binding sites also predicted expression patterns for as many as 71% of the genes in some gene sets. These results suggest that there is a robust relationship between cis and social regulation of brain gene expression, especially considering that we studied <15% of all known transcription factors. These results also suggest that transcriptional networks involved in the regulation of development in
Drosophila
are used to regulate behavioral development in adult honey bees. However, differences in gene regulation between these two processes are suggested by the finding that the promoter regions for the behaviorally related bee genes differed in both motif occurrence and G/C content relative to their
Drosophila
orthologs.
Industrial Decline in Greater Manchester 1966-1975: a Components of Change Approach
Authors: Mason Colin M.
Published: October 2006

The investigation of manufacturing employment change in Greater Manchester provides a provincial conurbation example to complement the well-documented case of industrial decline in London. Between 1966 and 1975 Greater Manchester lost one-quarter of its manufacturing employment, largely through plant closures. Surviving plants also lost employment while new jobs in plant openings only offset one-quarter of those lost in closures. The movement of industry into and out of the conurbation had a minor impact on employment change. In comparison with metropolitan areas in Development Areas Greater Manchester experienced a higher closure rate and lower opening rate. However, it was concluded that neither improved regional assistance nor existing firms and new establishment creation would provide sufficient new jobs to prevent continued industrial decline.
The Contribution of Council House Allocation to West Indian Desegregation in London, 1961-71
Authors: Peach Ceri , Shah Samir
Published: October 2006

Analysis of special tabulations of the 1971 census for the Greater London Council area indicates that the allocation of council housing had the main effect of re-sorting the West Indian population within the boroughs of high concentration rather than redistributing them between the areas of high and low concentration. While, so far, research effort has highlighted the discrimination in the type of housing allocated, this problem may be remedied without the other major problem of where immigrants are given housing being touched.
A Regional Comparison of House Price Inflation Rates in Britain, 1967-76
Authors: McAvinchey Ian D. , Maclennan Duncan
Published: October 2006

The paper presents by using regionally disaggregated data for the British Economic Planning Regions some questions on the usefulness of current macro-oriented approaches to the modelling of house price inflation. The paper indicates that such models should be restricted in their use to national levels. It argues that a more disaggregated approach to the analysis of house price changes would not only be locally useful but would take account of housing research on the micro level.
The Determination of the Price of Land
Authors: Evans Alan W.
Published: October 2006

Received theories of the land market are inadequate, since they ignore the supply of land. It is known that occupiers of land are usually unwilling to sell at the market price but require compensation for being forced to move. Incorporating this as a theory of supply into land market theory allows us to explain or predict that (a) urban sprawl will occur, in the absence of planning controls, (b) a development gains tax will slow down the rate of development of land and increase its price, (c) whether land is owner occupied or occupied by tenants will affect its development, and (d) powers of compulsory purchase may be necessary for certain kinds of development but may cause social costs.
Housing Policy Impacts on Ethnic Segregation Patterns: Evidence from Dusseldorf, West Germany
Authors: Waldorf Brigitte S.
Published: October 2006

Ethnic residential segregation has been of long-standing concern in cities throughout the world. Policy-makers are faced with decisions that potentially have a profound impact on these segregative patterns. This study illustrates the applicability of a recently developed analytical model of ethnic segregation and relocation in urban housing markets to housing policy evaluations. Using 1981 data for the city of Diisseldorf, West Germany, the effects of two housing policies are analysed: the first hypothesises an increase in housing supply, and the second simulates the effects of an urban renewal project. The results suggest that the accounting model is well suited to this type of analysis, and, as such, offers invaluable insights into spatial and compositional demographic shifts in response to housing policies.
FOB Mill Pricing and Plant Location when Demand is Linear but Non-uniform
Authors: Shieh Yeung-Nan
Published: October 2006

This paper examines the impact of non-uniform linear demand on plant location under FOB mill pricing. It shows that the principle of median location and the Rydell principle fail to apply, and some well-established results in plant location theory no longer hold when demand is linear but non-uniform.
The Influence of Location upon Profitability and Employment Change in Small Companies
Authors: Coombes M.G. , Storey D.J. , Watson R. , Wynarczyk P.
Published: October 2006

This paper examines the hypothesis that firms located in large urban areas suffer from location diseconomies which significantly reduce their profitability and propensity to create employment. This hypothesis is tested on a sample of companies located within a single region, the north of England, over the period 1974-81. The empirical results suggest that neither trading profits nor employment change are significantly influenced by location. However, the amount taken out of the business in the form of directors' remuneration, which on average swallowed up 61.5 per cent of trading profits, is significantly negatively related to employment change. This suggests that, with respect to employment creation, public policy should focus on influencing the size of directors' remuneration rather than on directly increasing trading profits. Fiscal policies may not be effective in this context, however, with the result that significantly influencing the behaviour of small firm directors may be a policy role best fitted to pro-active local economic development agencies.
'Rabbit Hutches on Postage Stamps': Planning, Development and Political Economy
Authors: Evans Alan W.
Published: October 2006

The supply of land for housing has been restricted by planning controls. The prices of land and of houses have risen in consequence. As a result land has been used with increasing intensity with infill, 'town cramming' and smaller houses on less land—'rabbit hutches on postage stamps'; a destruction of the urban environment of the many to preserve a rural environment for a few. Why is the supply of land restricted? Firstly, it is suggested, because the British misapprehend the degree of urbanisation in their own country. Secondly, because rural and farming interests ensure that the planning system operates in their favour. And thirdly, and most importantly, because the planning process is tilted in favour of the existing residents of an area who seek to preserve their environment by resisting intruders. A number of suggestions are made to resolve the situation by increasing the supply of land or reducing the demand for land.
A Second Look at the Bangkok Land and Housing Market
Authors: Dowall David E.
Published: October 2006

An earlier paper by the present author, published in this journal in 1989, reported on a detailed analysis of the Bangkok land and housing market, carried out in 1987-88. Based on a recent reassessment, this paper compares the performance of Bangkok's land and housing markets in 1974-84 and 1988-90. The results of the comparative analysis are striking: despite rapid increases in land conversion pressure and price increases, Bangkok's housing developers are still providing considerable amounts of affordable housing. Unconstrained by zoning, they have decentralised development projects and increased project densities dramatically.
Maximum Lot Size Zoning in Developing Countries
Authors: Pasha Hafiz A.
Published: October 2006

This paper identifies the principal motivations for resort to land rationing in the form of maximum lot size zoning in developing countries. Consequences of such regulation on utility levels, land values and metropolitan area are analysed within the spatial, general equilibrium framework of a 'semi-closed' city with two income groups—the poor and the rich. The paper demonstrates that realisation of the anticipated benefits from the regulation depends upon the features of the particular city where such legislation is contemplated, especially in terms of the pattern of intra-urban location of the two income groups.
Rent Control: Its Rationale and Effects
Authors: Sang Ho Lok
Published: October 2006

This paper discusses the rationale behind rent control and analyses its effects using a capital theory framework in combination with traditional bid rent analysis. The experience in Hong Kong and Ontario is found to support the author's hypothesis that in addition to the reasons given by other authors, rent control is a substitute for public housing spending and hence is popular among fiscally strained governments. The theoretical discussion confirms earlier findings and additionally provides insight into some of the differential effects on quality and maintenance that have been observed.
The Impact of Rent Control on Rents in the Free Sector
Authors: Hubert Franz
Published: October 2006

In most cases rent control covers only a part of the housing stock. This note provides a simple analysis of the impact which rent control and non-price rationing exert on the rent in the free sector. It is shown that, depending on the rationing mechanism, rents in the free sector can be higher or lower than in the absence of rent controls.
Housing Benefit and Income Redistribution
Authors: Gibbs Ian , Kemp Peter
Published: October 2006

This paper examines the effect of Housing Benefit on income distribution on the basis of data contained in the 1988 Family Expenditure Survey. Household income has been adjusted by means of equivalence scales so that like is compared with like. The results indicate that, though Housing Benefit makes a relatively small impact overall, it has a significant role in reducing income inequality among renters.
Causes of In-migration to Tel-Aviv Inner City
Authors: Schnell Izhak , Graicer Iris
Published: October 2006

Several constraints and motivations in explaining migration to the inner city of Tel-Aviv are analysed. It is argued that the process was triggered off by decline in new constructions relative to the constitution of new households in Israel. However, the back-to-the-city movement was not stimulated by a manipulative elite or by decline in housing prices in the inner city. Instead, the inner city became the preferred location of several groups of lifestyles including young urbanites, Yuppies and Dinkies, and young mobile households, as well as more family-oriented households seeking high-status flats in the inner city.
Individual Self-provision and the Scottish Housing System
Authors: Clapham David , Kintrea Keith , McAdam Gordon
Published: October 2006

This paper provides a preliminary examination of individual self-provision of housing in Scotland; that is, instances where individuals are directly involved in the production of their own house, rather than buying a house on the market. After a brief overview of the history of individual self-provision in Britain, the characteristics of the sector in Britain, and particularly in Scotland, are outlined. The core of the paper reports the results of a pilot survey of self-provision in Scotland. Four issues are examined: the type of self-provision; land availability; relationships with commercial interests; and local housing systems and access. It is concluded that self-provision is an important but mostly unrecognised source of new housing provision, whose incidence depends crucially on the nature of local housing systems and the extent to which planning policies are favourable in terms of land release and development control.
Residential Land Price Changes in Mexican Cities and the Affordability of Land for Low-income Groups
Authors: Ward Peter , Jimenez Edith , Jones Gareth
Published: October 2006

This research demonstrates that the price of residential land in Mexico declined significantly in real terms during the 1980s. Land prices appear to follow a cyclical trend which tracks Mexico's macro-economic performance. Data derived from advertised plot prices in newspapers, and from a large sample of household interviews conducted in low-income settlements in three intermediate-sized Mexican cities, suggest that, for the poor, real wage levels are the key determinant of changing affordability. The erosion of real wages has led to some decline in affordability, but this has largely been offset by multiple-earning strategies within households through which purchasing power may be maintained.
The Distribution of Housing Tax-expenditures and Subsidies in an Urban Area
Authors: Walker Bruce , Marsh Alex
Published: October 2006

This paper examines the distribution of housing tax-expenditures and subsidies among households in the owner-occupied and public-rented sectors in the Birmingham area, UK. Subsidies to tenants are defined as the difference between market rents and the rents actually set. Tax-expenditures to owner-occupiers are defined as the absence of tax on imputed rental income and capital gains. The results presented indicate that tax-expenditures tend to be more regressively distributed than subsidies to tenants arising from non-market pricing. The benefits from the latter are more dependent on a household's location and property type than on income. The paper concludes that efficiency and equity objectives are not met by the current housing finance system.
An Explanatory Model of City-size Distribution: Evidence from Cross-country Data
Authors: Alperovich Gershon
Published: October 2006

This paper utilises data from files of the World Bank to investigate the relevancy of a wide set of variables in explaining systematic variations of city-size distribution across countries. The Pareto exponent is employed as a measure of population concentration among cities of different sizes. The empirical results allow us to confirm a number of hypotheses. High degrees of economic development as measured by per capita GNP foster urban dispersal. Conversely, high degrees of government involvement in the economy and prevalence of significant scale and agglomeration economies promote urban concentration. Like most other cross-sectional studies, this study does not provide support to a dominating view in the economic development literature that at low levels of development the relation between economic development and population concentration is negative while at high levels the relation reverses and becomes positive.
Suburban Employment Centres: The Case of Chicago
Authors: McDonald John F. , Prather Paul J.
Published: October 2006

This paper uses data from the journey to work portion of the 1980 Census to estimate a polycentric model of employment density for the Chicago urbanised area. Distance to the Chicago central business district exerted a strong effect on employment density, but density was also influenced by proximity to three suburban employment centres. Some 27 per cent of total employment growth in metropolitan Chicago over the next decade was concentrated in these three subcentres.
Randstad Holland: A 'World City'?
Authors: Shachar Arie
Published: October 2006

The paper deals with the application of the concept of world city to the urban phenomenon of Randstad Holland. The enquiry into Randstad Holland as a world city in the making is motivated by the recent designation of Amsterdam, the Hague and Rotterdam by national planning authorities as international centres. After reviewing the evolution of the world city concept, the article specifies the main characteristics of a world city as an international management centre; a concentration of advanced producer services; and a very high level of physical and social infrastructure. Various studies of the European urban system are reviewed in order to identify the position of the Randstad within the new European urban hierarchy. Most of these studies position the Randstad among the four or five European urban agglomerations which can be defined as having marked world city characteristics. The empirical part of the article deals with internationalisation processes of the Randstad economy and draws some policy implications for the future planning and development of the Randstad.
Social Rented Housing: Valuable Asset or Unsustainable Burden?
Authors: Dieleman Frans M.
Published: October 2006

The Netherlands has maintained a high degree of intervention in the housing market through the 1980s. It also has a very large social rented sector which comprises 40 per cent of the total housing stock. The housing market regulation and the construction of large quantities of non-profit housing have created a stable level of production of new dwellings and an affordable housing stock. The large social rented sector offers shelter to a large population of low-income households; but it also accommodates many median and high-income groups, thereby avoiding extreme forms of housing segregation. Housing subsidies are a heavy burden on the national budget. A process of financial disengagement of the national government and the housing associations has been started. This will increase the independence of the non-profit housing sector from the political process, but will also lead to higher financial risks for the associations and more instability in this sector.
Planning the Randstad: Between Economic Growth and Sustainability
Authors: Priemus Hugo
Published: October 2006

The possibilities and limitations in internationalising the economy of the Randstad are considered, taking into account criteria of sustainability. The Randstad has a central position in the West European urban core region. National physical planning policies are strongly focused on the Randstad. A number of strategic projects are being developed to promote the attractiveness of the Randstad. At the same time, initiatives have been taken to strengthen the administrative cohesion within the Randstad. We show that the coordination between different strategic projects is weak and that priorities are unclear. A strategic plan for the Randstad is presented, aimed at a strengthening of its international position and its environmental qualities.
Normal Structure, Function, and Histology of the Spleen
Authors: Cesta Mark F.
Published: October 2006

The spleen is the largest secondary immune organ in the body and is responsible for initiating immune reactions to blood-borne antigens and for filtering the blood of foreign material and old or damaged red blood cells. These functions are carried out by the 2 main compartments of the spleen, the white pulp (including the marginal zone) and the red pulp, which are vastly different in their architecture, vascular organization, and cellular composition. The morphology of these compartments is described and, to a lesser extent, their functions are discussed. The variation between species and effects of aging and genetics on splenic morphology are also discussed.
Clinical Culture Surveillance of Carbapenem-Resistant Pseudomonas aeruginosa and Acinetobacter Species in a Teaching Hospital in São Paulo, Brazil: A 7-Year Study
Authors: Furtado Guilherme Henrique Campos , Martins Sinaida Teixeira , Machado Antônia Maria Oliveira , Wey Sérgio Barsanti , Medeiros Eduardo Alexandrino Servolo
Published: October 2006

Carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter species are worrisome nosocomial pathogens. After introduction of a preventive program involving clinical surveillance culture to reduce the spread of those pathogens, we observed an 80% decrease in the percentage of cultures that yielded carbapenem-resistant Acinetobacter isolates. The percentage of cultures that yielded carbapenem-resistant P. aeruginosa remained relatively stable during the intervention.
Nationwide Outbreak of Red Eye Syndrome Associated With Transfusion of Leukocyte-Reduced Red Blood Cell Units
Authors: Alonso-Echanove Juan , Sippy Brian D. , Chin Arthur E. , Cairns Lisa , Haley Rebecca , Epstein Jay S. , Richards Michael J. , Edelhauser Henry , Hedberg Katrina , Kuehnert Matthew J. , Jarvis William R. , Pearson Michele L. ,   the Transfusion-Associated Red Eye Syndrome Study Group
Published: October 2006

Objective.

To characterize red eye reactions occurring within 24 hours after receipt of units of leukocyte-reduced red blood cells, determine their etiology, and investigate their potential link to transfusion.

Methods.

We conducted a survey of transfusion facilities nationwide to determine the scope and magnitude of the reactions; performed case-control and cohort studies among transfused patients at the facility where most reactions occurred; and performed animal experiments, using cellulose acetate derivatives extracted from leukocyte-reduction filters and filter precursors, to reproduce reactions.

Results.

From January 1, 1997, through January 15, 1998, we identified 159 reactions in 117 patients from 17 states. Reactions were characterized by conjunctival erythema or hemorrhage (in 100% of patients), eye pain (in 62%), photophobia (in 46%), and decreased visual acuity (in 32%). Symptom onset occurred 1-24 hours after initiation of transfusion and resolved within a median of 5 days. Reactions were associated with transfusion sessions that included units of red blood cells filtered with a specific brand of filter, the LeukoNet filter (HemaSure) (odds ratio, 100.4; P< .001). There was a dose-response relationship between the number of LeukoNet-filtered units transfused and the attack rate for reactions, ranging from 0.8% among sessions in which 1 unit was transfused to 27.3% among sessions in which 3 or more units were transfused (P< .001). A similar ocular syndrome was elicited in rabbits injected with cellulose acetate derivatives extracted from unused LeukoNet filters or filter precursors. No reactions were reported after LeukoNet filters were withdrawn from the market.

Conclusions.

This transfusion-associated red eye syndrome was linked to a specific brand of leukocyte-reduction filter and likely resulted from cellulose acetate derivatives leached from the filter membrane.
Outbreak of Chlamydia pneumoniae Infection in a Japanese Nursing Home, 1999-2000
Authors: Nakashima Kazutoshi , Tanaka Takeshi , Kramer Michael H. , Takahashi Hiroshi , Ohyama Takaaki , Kishimoto Toshio , Toshima Hironori , Miwa Shigeyuki , Nomura Atsushi , Tsumura Naoki , Ouchi Kazunobu , Okabe Nobuhiko
Published: October 2006

Objective.

To identify risk factors for infection and severe illness due to Chlamydia pneumoniae.

Methods.

To identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study.

Setting.

A nursing home providing long-term and day care services for elderly patients in Japan.

Participants.

Fifty-nine residents and 41 staff members of a nursing home.

Results.

The attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P = .04).

Conclusions.

C. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.
Plasma Membrane Sterol Distribution Resembles the Surface Topography of Living Cells
Authors: Wüstner Daniel
Published: October 2006

Cholesterol is an important constituent of cellular membranes. It has been suggested that cholesterol segregates into sterol-rich and -poor domains in the plasma membrane, although clear evidence for this is lacking. By fluorescence imaging of the natural sterol dehydroergosterol (DHE), the lateral sterol distribution has been visualized in living cells. The spatial labeling pattern of DHE coincided with surface structures such as ruffles, microvilli, and filopodia with correlation lengths in the range of 0.8–2.5 μm. DHE staining of branched tubules and of nanotubes connecting two cells was detected. Dynamics of DHE in folded and plane membrane regions was comparable as determined by fluorescence recovery after photobleaching. DHE colocalized with fluid membrane-preferring phospholipids in surface structures and at sites of cell attachment as well as in the cleavage furrow of dividing cells, but it was not particularly enriched in those regions. Fluorescent sterol showed homogeneous staining in membrane blebs induced by F-actin disruption. Cross-linking the ganglioside GM1—a putative raft marker—did not affect the cell surface distribution of DHE. The results suggest that spatial heterogeneities of plasma membrane staining of DHE resolvable by light microscopy reflect the cell surface topography but not phase-separated sterol domains in the bilayer plane.
Predicting continental-scale patterns of bird species richness with spatially explicit models
Authors: Rahbek Carsten , Gotelli Nicholas J , Colwell Robert K , Entsminger Gary L , Rangel Thiago Fernando L.V.B , Graves Gary R
Published: October 2006

The causes of global variation in species richness have been debated for nearly two centuries with no clear resolution in sight. Competing hypotheses have typically been evaluated with correlative models that do not explicitly incorporate the mechanisms responsible for biotic diversity gradients. Here, we employ a fundamentally different approach that uses spatially explicit Monte Carlo models of the placement of cohesive geographical ranges in an environmentally heterogeneous landscape. These models predict species richness of endemic South American birds (2248 species) measured at a continental scale. We demonstrate that the principal single-factor and composite (species-energy, water-energy and temperature-kinetics) models proposed thus far fail to predict (r2⩽0.05) the richness of species with small to moderately large geographical ranges (first three range-size quartiles). These species constitute the bulk of the avifauna and are primary targets for conservation. Climate-driven models performed reasonably well only for species with the largest geographical ranges (fourth quartile) when range cohesion was enforced. Our analyses suggest that present models inadequately explain the extraordinary diversity of avian species in the montane tropics, the most species-rich region on Earth. Our findings imply that correlative climatic models substantially underestimate the importance of historical factors and small-scale niche-driven assembly processes in shaping contemporary species-richness patterns.
Nanostructures in photovoltaics
Authors: Catchpole Kylie R
Published: October 2006

The world has recently been waking up to the urgent need to move away from fossil fuels and towards a low-carbon economy. To achieve this, we need a way of producing electricity that is efficient, widely applicable and cheap. At the same time, there has recently been an appreciation of the tremendous scope for making entirely new types of devices, and even seeing new physics, by structuring matter at the nanoscale. Furthermore, the occurrence of self-assembly in nature suggests that a range of types of nanoscale structures could be made simply and cheaply. The application of nanostructures to photovoltaics combines a field of almost limitless possibilities with a problem of vital urgency. In this paper, some of the newer ideas emerging from this trend are described, along with how they challenge our ideas on what a solar cell looks like. We are at the beginning of a time of radically rethinking the design of the solar cell, which may lead to the exploitation of completely new physical ideas in achieving a sustainable energy future.