bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin of decadal El Niño–Southern Oscillation–like variability in a coupled general circulation model
Authors: Yeh Sang‐Wook , Kirtman Ben P.
Published: January 2006

The origin of decadal El Niño–Southern Oscillation–like variability (hereinafter referred to as DEV) is analyzed in coupled general circulation model (CGCM) simulations. The CGCM experiments test the null hypothesis for the existence of DEV, that is, that DEV is linear, damped, and stochastically forced by atmospheric internal dynamics. In order to test this hypothesis we employ the interactive ensemble coupling strategy. It is found that the spatially averaged variance of sea surface temperature anomaly (SSTA) and heat content anomaly (HCA) associated with the DEV is linearly related to the amplitude of atmospheric internal dynamics. This result suggests that the DEV is primarily noise forced but that damped coupled feedbacks and/or internal ocean dynamics enhance this variability. The SSTA variability associated with the DEV appears to be of a basin‐type standing mode with a triangular shape. However, the decadal evolution of the HCA associated with the DEV shows a systematic westward propagation from the central North Pacific and the eastern South Pacific. Both a singular vector analysis and noise variance analysis based on the coupled simulation results support the argument that atmospheric noise in the subtropics leads to the excitation of the DEV.
Characteristics and radiative impact of the aerosol generated by the Canberra firestorm of January 2003
Authors: Mitchell R. M. , O'Brien D. M. , Campbell S. K.
Published: January 2006

The extensive fires in southeastern Australia in January 2003 culminated in the Canberra firestorm of 18 January. The fires generated a pall of smoke that blanketed the Canberra area for the following week and affected the region for most of the following month. Analysis of Sun photometer data shows that aerosol optical depths τ500 > 7 were observed during the week following the firestorm. During the subsequent month the smoke aerosol dispersed, although background conditions (τ500 < 0.1) did not return until after significant rain in late February. Analysis of aerosol optical properties retrieved from sky radiance scans shows remarkably high single scattering albedo (ϖ440 ∼ 0.96) with only a small depression evident in the week following the firestorm. This indicates that the aerosols were significantly less absorbing than would be expected from smoke freshly generated by flaming combustion, possibly a result of inefficient combustion due to the extreme intensity of the fire, and marks them out as quite distinct from the more absorbing biomass burning aerosols encountered in the savannas of tropical Australia. The high single scattering albedo gave rise to mean radiative forcings of −50 W m−2 at the top of the atmosphere and −172 W m−2 at the surface during the week following the firestorm. Maximum heating rates are depressed by a factor of two at ϖ440 = 0.96 compared with ϖ440 = 0.88. Nevertheless, for plausible atmospheric profiles the large optical depths caused heating rates peaking at more than 10 K/day near the top of the smoke layer. The layer stabilized the lower troposphere through a combination of reduced surface heating and a positive gradient in heating rate through most of the layer. The enhanced stability suppressed surface temperatures and winds during the week following the firestorm, reducing the risk of renewed fire danger, and suggesting a useful role for aerosol effects in weather prediction models.
Spatiotemporal variations of snowmelt in Antarctica derived from satellite scanning multichannel microwave radiometer and Special Sensor Microwave Imager data (1978–2004)
Authors: Liu Hongxing , Wang Lei , Jezek Kenneth C.
Published: January 2006

We derived the extent, onset date, end date, and duration of snowmelt in Antarctica from 1978 to 2004 using satellite passive microwave scanning multichannel microwave radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I) data. A wavelet‐transform‐based method was developed to determine and characterize melt occurrences. About 9–12% of the Antarctic surface experiences melt annually. This is more than twice the surface melt extent measured in Greenland. Seasonally, surface melt primarily takes place in December, January, and February and peaks in early January. Regression analysis over the 25 year period of study reveals a negative interannual trend in surface melt. Nevertheless, the trend inference is not statistically significant. Large year‐to‐year fluctuations characterize the interannual variability. Extremely high melt occurred in the 1982/1983 and 1991/1992 summers, while extremely weak melt occurred in the 1999/2000 summer. A strong correlation with air temperature suggests that the melt index can serve as a diagnostic indicator for regional temperature variations. Periodic melting has been observed over Ross Ice Shelf, Ronne‐Filchner Ice Shelf, the West Antarctic ice streams, and outlet glaciers in the Transantarctic Mountains. The Antarctic Peninsula, West Ice Shelf, Shackleton Ice Shelf, Amery Ice Shelf, and the ice shelf along the Princess Ragnhild Coast experienced the most persistent and intensive melt and should be closely monitored for their stability in the future, given the recent disintegration of the Larsen Ice Shelf A and B.
Discrimination of the flow law for subglacial sediment using in situ measurements and an interpretation model
Authors: Kavanaugh Jeffrey L. , Clarke Garry K. C.
Published: January 2006

Subglacial hydrological and mechanical processes play a critical role in determining the flow characteristics and stability of glaciers and ice sheets. To study these processes, we have measured simultaneously basal water pressure, pore water pressure, sediment deformation, glacier sliding, and sediment strength beneath Trapridge Glacier, Yukon Territory, Canada. To interpret these data, we have developed a simple hydromechanical model of processes beneath a soft‐bedded alpine glacier. The glacier bed is divided into soft‐bedded regions that are hydraulically connected to the subglacial drainage system, soft‐bedded but hydraulically unconnected regions, and hard‐bedded regions. Each region is represented as a one‐dimensional column. The columns are coupled by a simple ice dynamics model that accounts for water‐pressure‐driven changes in basal shear stress distribution. Synthetic responses for subglacial instruments are calculated from the modeled basal conditions, providing a framework for improving interpretation of field records. The model is used to determine which of several till flow laws best represents conditions beneath Trapridge Glacier. Investigated are linear‐viscous, nonlinear‐viscous, nonlinear‐Bingham, and Coulomb‐plastic tills. Pore water pressures, sediment deformation profiles, and sliding rates are calculated for each flow law. Comparison of synthetic and field instrument responses suggests that till behavior is best represented as Coulomb‐plastic. Model results also suggest that the ploughmeter is the most diagnostic in situ indicator of till behavior currently available and that using long‐term observations of sediment deformation profiles in regions of varying pore water pressure can result in an underestimation of flow law nonlinearity.
Orbitally driven insolation forcing on Holocene climate trends: Evidence from alkenone data and climate modeling
Authors: Lorenz Stephan J. , Kim Jung‐Hyun , Rimbu Norel , Schneider Ralph R. , Lohmann Gerrit
Published: January 2006

A global spatial pattern of long‐term sea surface temperature (SST) trends over the last 7000 years is explored using a comparison of alkenone‐derived SST records with transient ensemble climate simulations with a coupled atmosphere‐ocean circulation model under orbitally driven insolation forcing. The spatial trend pattern both in paleo‐SST data and in model results shows pronounced global heterogeneity. Generally, the extratropics cooled while the tropics experienced a warming during the middle to late Holocene. We attribute these divergent Holocene climate trends to seasonally opposing insolation changes. Furthermore, climate mode changes similar to the Arctic/North Atlantic Oscillation are superimposed on the prevalent pattern. It is concluded that nonlinear changes in the entire seasonal cycle of insolation played a dominant role for the temporal evolution of Holocene surface temperatures. For understanding of marine proxy data, apart from the dominance of summer insolation in high latitudes, a notable shift in the maximum insolation of the year in low latitudes has to be taken into account, which may influence timing of phytoplankton production and thus alters the seasonal origin of temperature signals recorded in the proxies.
Characterization of ultrawideband antennas using transfer functions
Authors: Qing Xianming , Chen Zhi Ning , Chia Michael Yan Wah
Published: January 2006

Transfer functions are useful parameters for ultrawideband (UWB) antenna characterization. The response of an antenna system to any excitation can be completely determined in terms of the transfer functions (or the “impulse response” in time domain) of the antennas. In this paper, the transfer functions are defined as a transmitting antenna transfer function, a receiving antenna transfer function, and an antenna system transfer function to characterize UWB antenna systems readily and accurately. The transfer functions are expressed by ABCD and S parameters when the antenna system is considered as a two‐port network. As examples, an antipodal Vivaldi antenna and a disc cone antenna are investigated to validate the proposed method. The measured results are further verified by XFDTD simulation.
Late Cenozoic and modern stress fields in the western Fars (Iran): Implications for the tectonic and kinematic evolution of central Zagros
Authors: Lacombe O. , Mouthereau F. , Kargar S. , Meyer B.
Published: January 2006

The Zagros (Iran) developed during Mio‐Pliocene times in response to Arabia‐Eurasia convergence. The western Fars highlights a major bend of the deformation front and displays a remarkable set of nearly N‐S right‐lateral strike‐slip faults (the Kazerun‐Borazjan/Karebass/Sabz‐Pushan/Sarvestan faults) oblique at high angle to the belt. The region likely plays a major kinematic role by accommodating the change in shortening modes from partitioned in the western central Zagros to nonpartitioned in the eastern Zagros. The inversion of focal mechanisms from small and moderate earthquakes shows a consistent N020°–030° compression with a low ratio between differential stresses. This regime accounts for the combination of strike‐slip and thrust‐type mechanisms through likely σ2/σ3 permutations. Fault slip analysis reveals two successive late Cenozoic regional compressional trends, NE‐SW then N020°. The latter is in good agreement with the present‐day stress. The significance of the NE‐SW compression is discussed alternatively in terms of stress deviations or block rotations in relation to the strike‐slip fault system. Fieldwork and satellite imagery suggest that these faults behave first as transfer faults during folding of the cover and later as strike‐slip faults, in agreement with the succession of stress regimes and the evolution of the dominant deformation style from thin‐skinned to thick‐skinned. The first‐order stability of the collision‐related state of stress since ∼5 Ma supports that the Arabia‐Eurasia convergence did not give rise to partitioning in the western Fars but rather was (and is still) accommodated by distributed deformation involving both shortening and strike‐slip motion throughout the cover and the basement.
A transferable electrostatic map for solvation effects on amide I vibrations and its application to linear and two-dimensional spectroscopy
Authors: la Cour Jansen Thomas , Knoester Jasper
Published: January 2006

A method for modeling infrared solvent shifts using the electrostatic field generated by the solvent is presented. The method is applied to the amide I vibration of N-methyl acetamide. Using ab initio calculations the fundamental frequency, anharmonicity, and the transition dipoles between the three lowest vibrational states are parametrized in terms of the electrostatic field. The generated map, which takes into account the electric field and its gradients at four molecular positions, is tested in a number of common solvents. Agreement of solvent shift and linewidths with experimental Fourier transform infrared (FTIR) data is found to within seven and four wave numbers, respectively, for polar solvents. This shows that in these solvents electrostatic contributions dominate solvation effects and the map is transferable between these types of solvents. The effect of motional narrowing arising from the fast solvent fluctuations is found to be substantial for the FTIR spectra. Also the two-dimensional infrared (2DIR) spectra, simulated using the constructed map, reproduce experimental results very well. The effect of anharmonicity fluctuations on the 2DIR spectra was found to be negligible.
Coaxial carbon nanotubes as shielded nanowires
Authors: Brothers Edward N. , Scuseria Gustavo E. , Kudin Konstantin N.
Published: January 2006

We report transverse polarizabilities of coaxial carbon nanotubes using first principles density functional theory. These results demonstrate a shielding of the inner nanotube from electric fields by the outer nanotube. This study has implications for nanoelectronics, specifically for the possibility of using coaxial nanotubes as nanoelectrical wires. Shielding is predicted to be on the order of 95% by high-level polarizability calculations. This shielding occurs regardless of whether the outer nanotube is metallic or semiconducting. In addition, a series of calculations on coaxial nanotubes where the inner nanotube is not centered show that the shielding still occurs with approximately the same magnitude. These calculations therefore indicate that it would be possible to use a coaxial carbon nanotube as a shielded nanowire.
Control of Li2 wave packet dynamics by modification of the quantum mechanical amplitude of a single state
Authors: Lerch Eliza-Beth W. , Dai Xingcan , Gilb Stefan , Torres Elva A. , Leone Stephen R.
Published: January 2006

Sequences of pulses with different spectra are used to control rotational wave packet dynamics in Li2 by exploiting quantum interference phenomena. Wave packet superpositions are excited in a two-step resonant Raman process by two different pulses. Interferences between individual states shared by both wave packets can be used to enhance or destroy specific components of a superposition by varying the time delay between the pulses and/or the relative phase within the pulses. Elimination of selected quantum beats is achieved by greater than 94% for each case. A simple, yet effective, method for generating different color phase-locked pairs of laser pulses in a liquid-crystal pulse shaper setup without the need for interferometric stabilization schemes is described. The ability to manipulate single states of a superposition is an important advancement for intuitive control schemes and provides a potential new approach for initialization schemes in the field of quantum information.
Partition functions of supersymmetric gauge theories in noncommutative R2D and their unified perspective
Authors: Sako Akifumi , Suzuki Toshiya
Published: January 2006

We investigate cohomological gauge theories in noncommutative R2D. We show that vacuum expectation values of the theories do not depend on noncommutative parameters, and the large noncommutative parameter limit is equivalent to the dimensional reduction. As a result of these facts, we show that a partition function of a cohomological theory defined in noncommutative R2D and a partition function of a cohomological field theory in R2D+2 are equivalent if they are connected through dimensional reduction. Therefore, we find several partition functions of supersymmetric gauge theories in various dimensions are equivalent. Using this technique, we determine the partition function of the N=4 U(1) gauge theory in noncommutative R4, where its action does not include a topological term. The result is common among (8-dim, N=2), (6-dim, N=2), (2-dim, N=8) and the IKKT matrix model given by their dimensional reduction to 0-dim.
The generalized Davey-Stewartson equations, its Kac-Moody-Virasoro symmetry algebra and relation to Davey-Stewartson equations
Authors: Güngör F. , Aykanat Ö.
Published: January 2006

We compute the Lie symmetry algebra of the generalized Davey-Stewartson (GDS) equations and show that under certain conditions imposed on parameters in the system it is infinite-dimensional and isomorphic to that of the standard integrable Davey-Stewartson equations which is known to have a very specific Kac-Moody-Virasoro loop algebra structure. We discuss how the Virasoro part of this symmetry algebra can be used to construct new solutions, which are of vital importance in demonstrating existence of blow-up profiles, from known ones using Lie subgroup of transformations generated by three-dimensional subalgebras, namely sl(2,R). We further discuss integrability aspects of GDS equations.
The Faraday effect revisited: General theory
Authors: Cornean Horia D. , Nenciu Gheorghe , Pedersen Thomas G.
Published: January 2006

This paper is the first in a series revisiting the Faraday effect, or more generally, the theory of electronic quantum transport/optical response in bulk media in the presence of a constant magnetic field. The independent electron approximation is assumed. At zero temperature and zero frequency, if the Fermi energy lies in a spectral gap, we rigorously prove the Widom-Streda formula. For free electrons, the transverse conductivity can be explicitly computed and coincides with the classical result. In the general case, using magnetic perturbation theory, the conductivity tensor is expanded in powers of the strength of the magnetic field B. Then the linear term in B of this expansion is written down in terms of the zero magnetic field Green function and the zero field current operator. In the periodic case, the linear term in B of the conductivity tensor is expressed in terms of zero magnetic field Bloch functions and energies. No derivatives with respect to the quasimomentum appear and thereby all ambiguities are removed, in contrast to earlier work.
The performance of semilocal and hybrid density functionals in 3d transition-metal chemistry
Authors: Furche Filipp , Perdew John P.
Published: January 2006

We investigate the performance of contemporary semilocal and hybrid density functionals for bond energetics, structures, dipole moments, and harmonic frequencies of 3d transition-metal (TM) compounds by comparison with gas-phase experiments. Special attention is given to the nonempirical metageneralized gradient approximation (meta-GGA) of Tao, Perdew, Staroverov, and Scuseria (TPSS) [Phys. Rev. Lett. 91, 146401 (2003)], which has been implemented in TURBOMOLE for the present work. Trends and error patterns for classes of homologous compounds are analyzed, including dimers, monohydrides, mononitrides, monoxides, monofluorides, polyatomic oxides and halogenides, carbonyls, and complexes with organic π ligands such as benzene and cyclopentadienyl. Weakly bound systems such as Ca2, Mn2, and Zn2 are discussed. We propose a reference set of reaction energies for benchmark purposes. Our all-electron results with quadruple zeta valence basis sets validate semilocal density-functional theory as the workhorse of computational TM chemistry. Typical errors in bond energies are substantially larger than in (organic) main group chemistry, however. The Becke-Perdew’86 [Phys. Rev. A 38, 3098 (1988); Phys. Rev. B 33, 8822 (1986)] GGA and the TPSS meta-GGA have the best price/performance ratio, while the TPSS hybrid functional achieves a slightly lower mean absolute error in bond energies. The popular Becke three-parameter hybrid B3LYP underbinds significantly and tends to overestimate bond distances; we give a possible explanation for this. We further show that hybrid mixing does not reduce the width of the error distribution on our reference set. The error of a functional for the s-d transfer energy of a TM atom does not predict its error for TM bond energies and bond lengths. For semilocal functionals, self-interaction error in one- and three-electron bonds appears to be a major source of error in TM reaction energies. Nevertheless, TPSS predicts the correct ground-state symmetry in the vast majority of cases and rarely fails qualitatively. This further confirms TPSS as a general purpose functional that works throughout the periodic table. We also give workstation timing comparisons for the 645-atom protein crambin.
The small planarization barriers for the amino group in the nucleic acid bases
Authors: Wang Suyun , Schaefer Henry F.
Published: January 2006

The amino group in the nucleic acid bases frequently interacts with other bases or with other molecular systems. Thus any nonplanarity of the amino group may affect the molecular recognition of nucleic acids. Ab initio Hartree-Fock (HF) and second-order Møller-Plesset perturbation (MP2) levels of theory have been used to obtain the equilibrium geometries of the Cl and Cs structures for five common nucleic acid bases. The energy barriers between the Cl and Cs structures have also been predicted. A series of correlation consistent basis sets up to cc-pCVQZ and aug-cc-pVQZ has been used to systematically study the dependence of the amino group nonplanarity. The equilibrium geometries of the nucleic acid bases with an amino group, including adenine, guanine, and cytosine, are examined carefully. At the MP2 level of theory, larger basis sets decrease the extent of nonplanarity of the amino group, but the decrease slows down when the QZ basis sets are used, demonstrating the intrinsic property of nonplanarity for guanine. For adenine and cytosine the situation is less clear; as the HF limit is approached, these two structures become planar. Addition of core correlation effects or diffuse functions further decreases the degree of nucleic acid base nonplanarity, in comparison to the original cc-pVXZ (X=D, T, and Q) basis sets. The aug-cc-pVXZ basis shows smaller degrees of nonplanarity than the cc-pCVXZ sets. The aug-cc-pVXZ basis is less size dependent than the cc-pVXZ and cc-pCVXZ sets in the prediction of the amino-group-related bond angles and dihedral angles and energy barriers for adenine, guanine, and cytosine. The cc-pCVQZ and aug-cc-pVQZ MP2 results may be regarded as benchmark predictions for the five common bases. The predicted classical barriers to planarization are 0.02 (adenine), 0.74 (guanine), and 0.03(cytosine)kcalmol−1.
Resistive switching and data reliability of epitaxial (Ba,Sr)TiO3 thin films
Authors: Oligschlaeger R. , Waser R. , Meyer R. , Karthäuser S. , Dittmann R.
Published: January 2006

We report on resistive switching of capacitor-like SrRuO3∕Ba0.7Sr0.3TiO3∕Pt thin films epitaxially grown on SrTiO3 substrates. We observe a weak but stable hysteresis in the current-voltage curve. By applying short voltage pulses, a high or low resistive state as well as intermediate states can be addressed even at room temperature. We demonstrate a multiple-branch hysteresis curve corresponding to multilevel switching modus revealing different subloops for different write voltages. Furthermore reliability issues such as cycling endurance and data retention are presented. Read-write operations over 10000cycles show a fatigue-like drift of both resistance states. No data loss is found upon continuous readout.
Electron mobility in graded AlGaN alloys
Authors: Rajan Siddharth , DenBaars Steven P. , Mishra Umesh K. , Xing Huili (Grace) , Jena Debdeep
Published: January 2006

Polarization gradients in graded AlGaN alloys induce bulk electron distributions without the use of impurity doping. Since the alloy composition is not constant in these structures, the electron scattering rates vary across the structure. Capacitance and conductivity measurements on field effect transistors were used to find mobility as a function of depth. The effective electron mobility at different depths calculated from theory closely matched the measured mobility. Local bulk mobility values for different AlGaN compositions were found, and the electron mobility in AlGaN as a function of alloy composition was deduced. These were found to match with theoretical calculations.
Magnetic coding in systems of nanomagnetic particles
Authors: Chakraverty S. , Ghosh B. , Kumar S. , Frydman A.
Published: January 2006

Nanomagnetic systems show exotic memory effects in the dc magnetization as a function of temperature. We present magnetization measurements on systems of nanomagnetic particles that show that such systems store the memory of either decrease or increase of magnetic field enabling a magnetic “coding” of “0”s and “1”s. Application of a field larger than a critical field, H* erases the memory effects. We show that this behavior can be explained by a wide distribution of grain sizes having different blocking temperatures. The effect can be used as a tool for measuring spacial and temporal magnetization changes of a magnetic surface.
Scalable dope-coded biosensing particles for protein detection
Authors: Ly Nguyen , Tao Nongjian
Published: January 2006

We present a method to fabricate, assemble dope-coded biosensing particles, and demonstrate a scalable high throughput protein detection application. The coded biosensing particles (8μm in diameter and 280nm thick) are composed of biosensing/coding/magnetic/adhesive layers and coded via patterned boron doping. Coding via doping is powerful in that it can be easily decoded, permits scalability of bit sizes down to tens of nanometers, generates a large number of codes, and retains uniform particle size and shape independent of particle code for consistent protein analysis. Following suspension phase protein binding, the dope-coded biosensing particles are extracted with an external magnet and analyzed with an atomic force microscope.
Optically switchable twist nematic grating based on a dye-doped liquid crystal film
Authors: Huang San-Yi , Wu Shing-Trong , Fuh Andy Ying-Guey
Published: January 2006

The adsorption rate of methyl red dyes on a polymer surface is studied and determined to be much faster than that on indium-tin-oxide-coated glass. Therefore, an optically switchable twist-nematic grating is fabricated using a dye-doped liquid crystal cell, with a glass substrate coated with a polymer relief grating.
Gain amplification and lasing properties of individual organic nanofibers
Authors: Quochi F. , Cordella F. , Mura A. , Bongiovanni G. , Balzer F. , Rubahn H.-G.
Published: January 2006

We study gain and lasing processes in individual self-assembled organic nanofibers grown on mica substrates. The gain-induced response of the nanofibers is found to depend sensitively on the fiber structure. In homogeneous fibers where no coherent optical feedback is present, high net optical gain (of up to 103cm−1) results in spectral narrowing at the material gain peaks. In the case of strong optical feedback, which occurs in long nanofibers with randomly distributed scattering centers, gain is in turn responsible for low-threshold coherent random laser action.
Morphological and compositional changes in the SiO2∕SiC interface region induced by oxide thermal growth
Authors: Soares G. V. , Radtke C. , Baumvol I. J. R. , Stedile F. C.
Published: January 2006

Changes in morphology and composition of interfacial regions of thermally grown SiO2 films on SiC in dry O2 induced by reoxidations were investigated using atomic force microscopy and oxygen profiling. The gradual oxygen profile near the interface in oxides grown at 1100°C evidences a transition region between SiO2 and SiC. Reoxidation at 950°C leads to a decrease of the transition region thickness, while reoxidation at 1100°C increases the transition region thickness. These results are discussed in terms of the role played by the reoxidation temperature on the formation and consumption of carbon compounds in the SiO2∕SiC interface region.
Effect of Gd implantation on the structural and magnetic properties of GaN and AlN
Authors: Han Sang Youn , Hite J. , Thaler G. T. , Frazier R. M. , Abernathy C. R. , Pearton S. J. , Choi H. K. , Lee W. O. , Park Y. D. , Zavada J. M. , Gwilliam R.
Published: January 2006

Gd + ions were implanted at total doses of 3–6×1014cm2 into single-crystal GaN or AlN epilayers grown on sapphire substrates and annealed at 700–1000°C. The implanted Gd showed no detectable diffusion in either material after annealing, as measured by secondary ion mass spectrometry, corresponding to a diffusion coefficient <8×10−12cm2s−1. Under all annealing conditions, x-ray diffraction shows the formation of second phases. In the case of GaN, these include Gd3Ga2, GdN, and Gd, while for AlN only Gd peaks are observed. Both the GaN and AlN show high saturation magnetization after annealing at 900°C (∼15emucm−3 for GaN and ∼35emucm−3 for AlN). The magnetization versus temperature characteristics of the Gd-implanted GaN show a blocking behavior consistent with the presence of precipitates, whereas the AlN shows a clear difference in field-cooled and zero-field-cooled magnetization to above room temperature which may also be due to Gd inclusions.
Fields of Influence of Productivity Change in EU Intercountry Input—Output Tables, 1970–80
Authors: van der Linden Jan A , Oosterhaven Jan , Cuel Federico A , Hewings Geoffrey J D , Sonis Michael
Published: January 2006

The potential influence of changes in productivity is explored for each sector in each country on the intercountry Leontief-inverse of the European Union (EU) for two time periods, 1970 and 1980. The methodology employed is a weighted variant of the field of influence of column change; the empirical outcomes will be analyzed in three ways. First, the impact of comparable changes in productivity in every sector will be estimated in terms of its contribution to the aggregate value of the Leontief-inverse as well as on its spatial structure. From this estimation, propulsive sectors are identified as those sectors that produce the largest increase in the overall interdependence between all sectors in all EU-countries. Moreover, the propulsiveness of sectors will be spatially decomposed into four components: a ‘domestic’ effect, an ‘intercountry-spillover’, an ‘intercountry-return’, and a ‘rest of the EU’ effect on sectoral interdependence. Second, the analysis will examine how the columns of the intercountry Leontief inverse would change as a consequence of EU-wide changes in technology. This process will enable the identification of ‘reactive’ sectors, those sectors whose multipliers are most sensitive to EU-wide factor productivity increases. Third, the rows of the intercountry Leontief-inverse are considered in terms of their changes as a consequence of EU-wide changes in productivity. This approach identifies ‘dependent’ sectors, those sectors whose production level is most sensitive to overall changes in productivity within the EU.
Spatial Dimensions of Environmental Policies for Transboundary Externalities: A Spatial Price Equilibrium Approach
Authors: Verhoef Erik T , Nijkamp Peter
Published: January 2006

In this paper we present a framework for analyzing spatial aspects of environmental policies in the regulation of transboundary externalities. A spatial price equilibrium model for two regions is constructed, where interactions between these regions can occur via trade, via mutual environmental spillovers as a result of the externality that arises from production, and via uncoordinated taxes when the regions do not behave cooperatively. The additional complications arising from emissions caused by the endogenous transport flows are also considered explicitly. We consider the performance of production taxes, consumption taxes, and the combination of these two, both with and without optimal policy coordination.
Employment Restructuring and Household Survival in ‘Postcommunist Transition’: Rethinking Economic Practices in Eastern Europe
Authors: Smith Adrian
Published: January 2006

Within the context of rapid structural adjustment and the onslaught of neoliberal policies, this paper explores the varied trajectories and processes of employment restructuring in ‘postcommunist’ East-Central Europe. I first examine some of the comparative dimensions of employment and labour-market change in the region. The differential links between uneven employment loss and unemployment are explored to highlight the diverse national experiences of labour restructuring. I then go on to assess the links between employment restructuring and increasing nonparticipation in the labour market, again highlighting the importance of national differences which belie neoliberal notions of a unidimensional transition to capitalist employment relations. Having established the severity of the ‘employment shocks' across East-Central Europe, I then go on to examine the links between labour-market restructuring and emergent social inequality since 1989. The polarisation of employment opportunities and constraints provides a context for discussing the development of household economic practices that lie outside the ‘formal’, emergent capitalist economy. Through an exploration of a household data set for Bulgaria I examine the ways in which households in different labour-market positions have developed ‘strategies' that involve economic activities constituted outside of formal capitalist, market relations. On the basis of this analysis I argue that a theoretical space becomes opened, through which it is possible to situate household economic practices not solely as ‘responses' to the austerity of transition, but as constitutive of alternative sites of economic relations with their own autonomies and histories.
The Geographies of the National Minimum Wage
Authors: Sunley Peter , Martin Ron
Published: January 2006

Geographers have recently argued that labour-market regulation interacts with market forces in profoundly different ways in different local labour markets. We illustrate this argument by using the case of the new statutory minimum wage in Britain. We consider whether the introduction of the national minimum wage represents a genuine departure from the preceding neoliberal labour-market regime, and examine how far it will begin to redress some of the pronounced geographical inequality in wages across local labour markets which developed under that regime. To provide comparative context, we examine the international geography of minimum wages and assess whether, and to what extent, the new UK minimum wage indicates a shift towards a new model of labour-market governance and regulation. We then review the geography of low pay in the United Kingdom and consider the possible geographical impact of the new national minimum wage. We argue that the effects of the minimum will vary depending on the nature of local labour-market characteristics. Then, perhaps most contentiously, the case is considered for regionally differentiating the minimum wage to reflect geographical differences in the cost of living. Finally, we examine the arguments for and against a single uniform national minimum in the light of administrative systems operated in other countries.
The Determinants of Structural Change in the European Union: A New Application of RAS
Authors: van der Linden Jan A , Dietzenbacher Erik
Published: January 2006

In economic theory and practice, technological developments and changes in relative prices lead to changes in the input mix of one or more industries. Via intersectoral and interregional relations, this affects the entire production structure. In analysing the structural changes in an economy, changes in the input coefficients are a major determinant. Typically, however, this determinant is not unravelled further into its underlying sources. In the present paper we apply the RAS method to decompose the input coefficient changes into column-specific, row-specific, and cell-specific changes. They indicate the change in the intermediate input intensity of a sector, the average substitution of the intermediate goods and services provided by a sector, and the sector-specific substitutions, respectively. The method is applied to input–output tables of European Union member states, as issued every five years between 1965 and 1985. The usefulness of the RAS method as a descriptive tool is established.
Balancing Competing Principles of Environmental Equity
Authors: Atkinson Giles , Machado Fernando , Mourato Susana
Published: January 2006

Diverse and competing principles of equity are argued to be relevant to the burden-sharing problem for environmental improvement programmes. In this paper, a survey-based approach is used to reconcile this conflict, which is defined as sharing of the costs of an environmental programme among different individuals or groups. Respondents were asked to rank hypothetical individuals or groups on the basis of differences in relevant characteristic attributes. These attributes reflect the degree to which individuals are ‘responsible’ for the problem, ‘benefit’ from the policy change implemented, and are ‘able to pay’ for the programme. The econometric analysis of responses casts light on the magnitude of trade-offs between, for example, burden-sharing rules based on the polluter-pays principle and some of its alternatives. Our results indicate that these trade-offs do exist and, furthermore, are significant. Assessment of trade-offs in this way could be an important input into the design of mixed criteria rules for sharing burdens.
The Politics of Multilevel Environmental Governance: Subsidiarity and Environmental Policy in the European Union
Authors: Jordan Andrew
Published: January 2006

Subsidiarity, the principle which says that action should be taken at the lowest effective level of governance, is a potentially powerful concept around which a debate about the optimal assignment of tasks across different administrative levels of the European Union (EU) could be constructed. Its sudden incorporation into mainstream European discourse in the early 1990s provided an unprecedented opportunity for such a debate to take place. However, for various reasons this opportunity was spurned and subsidiarity has since metamorphosed into a technical process of legislative reform dubbed ‘Better Law-Making’. By analysing recent experience in the water sector through the lens of ‘new’ institutional theory, the author reveals that, far from undermining the framework of EU environmental policy, instead, the reforms have led to the tightening of some existing standards, although less important issues are being devolved to national authorities. It is debatable whether the political outcomes of the reform process to date were fully expected or desired by those states that advocated greater subsidiarity in the first place. There is precious little evidence that European environmental governance has moved much ‘closer’ to European citizens as a result of subsidiarity.
Testing for Spatial Autocorrelation among the Residuals of the Geographically Weighted Regression
Authors: Leung Yee , Mei Chang-Lin , Zhang Wen-Xiu
Published: January 2006

Geographically weighted regression (GWR) is a useful technique for exploring spatial nonstationarity by calibrating, for example, a regression model which allows different relationships to exist at different points in space. In this line of research, many spatial data sets have been successfully analyzed and some statistical tests for spatial variation have been developed. However, an important assumption in these studies is that the disturbance terms of the GWR model are uncorrelated and of common variance. Similar to the case in the ordinary linear regression, spatial autocorrelation can invalidate the standard assumption of homoscedasticity of the disturbances and mislead the results of statistical inference. Therefore, developing some statistical methods to test for spatial autocorrelation is a very important issue. In this paper, two kinds of the statistical tests for spatial autocorrelation among the residuals of the GWR model are suggested. Also, an efficient approximation method for calculating the p-values of the test statistics is proposed. Some simulations are run to examine the performances of the proposed methods and the results are encouraging. The study not only makes it possible to test for spatial autocorrelation among the GWR residuals in a conventional statistical manner, but also provides a useful means for model validation.
The Geography of Japanese Development Aid to China, 1978–98
Authors: Muldavin Joshua
Published: January 2006

Japan is the largest donor of development aid to China, and China is the largest recipient of international aid and arguably the most significant emergent transitional economy in the world. A survey of Japan's aid is helpful in any attempt to understand the impact of aid on China's national and regional development and on state strategies. Japan's aid is closely tied to the health of Japan's economy—the second largest economy in the world. Though certainly not unique in this regard, Japan's aid has a reputation for serving Japan's own national interests at the expense of the recipient nation's environmental and social conditions. The results of this survey reveal: (a) clearly defined and specific geographic patterns to Japan's aid to China; (b) changing sectoral patterns in Japan's aid to China; (c) important institutional changes underway in Japan's aid programs; and (d) a transfer of capital from Japan to China which serve the divergent goals of each state, though not necessarily in ways intended by each state.
Science Parks: Actors or Reactors? Canadian Science Parks in Their Urban Context
Authors: Shearmur Richard , Doloreux David
Published: January 2006

In response to the current accepted wisdom that we are now in a ‘knowledge economy’, where economic growth is directly linked to the capacity to gather and analyse information, an increasingly popular policy approach has been to foster the development of science parks. These parks, it is argued, contribute to the development of learning regions' by encouraging knowledge transfer between academic institutions and ‘high-tech’ or ‘knowledge-intensive’ establishments, thereby bringing about start-ups and growth in these sectors. Over the last 25 years, 17 such parks have opened in Canada, and in this paper the authors set out to answer two questions. First, what do these parks consist of? Second, can it be shown that they stimulate high-tech employment (whether in the manufacturing or service sectors) in the regions in which they are located? It is found that there is no link between the opening of a science park and employment growth in high-tech sectors.
Agent-Based Models and Individualism: Is the World Agent-Based?
Authors: O'Sullivan David , Haklay Mordechai
Published: January 2006

Agent-based models (ABMs) are an increasingly popular tool in the social sciences. This trend seems likely to continue, so that they will become widely used in geography and in urban and regional planning. We present an overview of examples of these models in the life sciences, economics, planning, sociology, and archaeology. We conclude that ABMs strongly tend towards an individualist view of the social world. This point is reinforced by closer consideration of particular examples. This discussion pays attention to the inadequacy of an individualist model of society with reference to debates in social theory. We argue that because models are closed representations of an open world it is important that institutions and other social structures be explicitly included, or that their omission be explained. A tentative explanation for the bias of ABMs is offered, based on an examination of early research in artificial intelligence and distributed artificial intelligence from which disciplines the approach is derived. Some implications of these findings are discussed. We indicate some useful research directions which are beginning to tackle the individualism issue directly. We further note that the underlying assumptions of ABMs are often hidden in the implementation details. We conclude that such models must be subject to critical examination of their assumptions, and that model builders should engage with social theory if the approach is to realise its full potential.
Housing Consumption in Urban China: A Comparative Study of Beijing and Guangzhou
Authors: Li Si-ming
Published: January 2006

The Chinese government has made repeated attempts to end the so-called welfare provision of housing so as to reduce the burden on the state and the individual work units. Development companies have been set up to undertake housing construction and the housing units sold as commodities; these are referred to as ‘commodity housing’. The author conducts a comparative study of housing consumption in Beijing and Guangzhou, drawing upon two surveys of newly completed commodity housing conducted in 1996. In Beijing, which is dominated by the traditional socialist system of economic and social organisation, only a tiny portion of such housing is traded on the open market. In Guangzhou, where many of the market-oriented reform measures were first experimented with, the open market already accounts for a substantial proportion of the newly constructed stock. In both Beijing and Guangzhou, however, the work unit still constitutes the single most important buyer and distributor of commodity housing. Further, if the analysis is restricted to the subsidised sectors, which also include housing managed by the municipal housing bureau and resettlement housing, a comparison of the two samples reveals quite similar differential factors underlying housing consumption in the two cities, despite their difference in social and economic structure. The traditional redistributive system still exerts tremendous influence on housing consumption, even in cities renowned for their openness and market orientation. Certain differences in the results between the two cities are also revealed. For example, seniority is important only in Beijing, whereas professional and technical workers assume a special position only in Guangzhou. These differences point towards the importance of contextual considerations in the study of housing consumption in China.
Strategies for Global Competition: Transnational Chemical Firms and Singapore's Chemical Cluster
Authors: Wang Jason H J , Yeung Henry Wai-Chung
Published: January 2006

The strong performance of Singapore's chemical industry in recent years has increased public awareness about the importance of this obscure sector in the Singapore economy. In the public rhetoric, much of this robust growth is attributed to the industrial policies implemented by the Singapore government. However, the ultimate decision to built a multibillion dollar chemical-processing plant in resource-scarce Singapore still depends very much on the global strategies of transnational chemical firms (CTNCs). The authors propose a firm-level perspective to aid in understanding the development of Singapore's chemical industry. They argue that the global strategies of CTNCs have a vital role to play in promoting growth within the Singapore chemical industry cluster. Conceived under the 1991 Strategic Economic Plan, the idea of clustering represents a radically different approach to the development of the petroleum-refining, petrochemicals, specialty chemicals, and pharmaceutical industries where previously each was deemed a separate activity. Based on field research into over forty subsidiaries and local suppliers of CTNCs in Singapore, the authors highlight the importance of two major contextual influences on the global strategies of CTNCs: rising global competition and the huge market potential offered by developing countries. Given these circumstances, CTNCs have relied on their established capabilities to formulate spatial strategies for increasing global competitiveness. In Singapore, subsidiaries of CTNCs have tapped into cluster-based advantages to enhance their capabilities, thereby contributing to the further growth of Singapore's chemical industry cluster.