bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporating systems dynamics and spatial heterogeneity in integrated assessment of agricultural production systems
Authors: ANTLE JOHN M. , STOORVOGEL JETSE J.
Published: January 2006

Agricultural systems are complex and dynamic, being made up of inter-acting bio-physical and human sub-systems. Moreover, agricultural systems are re-markably diverse, both within geographic regions and across regions. Accordingly, this paper focuses on dynamics and heterogeneity in coupled, multi-disciplinary simulation models of agricultural systems. We begin with a discussion of the principal features of agricultural production systems. We then present an example of a ‘loosely coupled’ model, the type of model most researchers have used to represent agricultural systems. We discuss the loosely coupled model's features and limitations, and show how it can be modified to incorporate feedbacks among sub-models. Finally, we use a case study of a hillside production system in Ecuador to illustrate the importance of model coupling, dynamics and heterogeneity in the analysis of production systems. This example shows that feedbacks and threshold effects are most important at sites most vulnerable to tillage erosion.
Collective action in community management of grazing lands: the case of the highlands of northern Ethiopia
Authors: BENIN SAMUEL , PENDER JOHN
Published: January 2006

Collective action can play a significant role in sustainable management of common grazing lands through restricting access and regulating use. However, it is not clear why there are often violations of grazing restrictions in equilibrium. This paper first presents a theoretical framework of collective action in community management of grazing lands that explicitly models individual violations behaviour. Then data from the highlands of Amhara region of Ethiopia are used to test the model predictions to examine the impact of policy-relevant factors on collective establishment of grazing restrictions and violations of grazing restrictions. Econometric results show that collective action in community grazing land management is likely to be more beneficial and effective in communities with better market access or higher populations. Collective action, on the other hand, is less likely to be successful in communities with greater social, economic, or cultural heterogeneity or more affluent members. Factors related to greater livestock profitability, such as rainfall, or fixed costs of negotiating agreements, such as total land area of the community, have ambiguous effects, as they are associated with establishment of grazing restrictions as well as violating the restrictions.
Bio-economic development of floodplains: farming versus fishing in Bangladesh
Authors: ISLAM MURSALEENA , BRADEN JOHN B.
Published: January 2006

This paper explores economic development in the floodplain of large rivers, where both economic and ecological factors need to be considered for effective management. Floodplain management policies in Bangladesh emphasize structural changes to enhance agricultural production. However, these structural changes reduce fisheries production, an important natural resource sector and a source of subsistence for the rural poor. We develop a model where net returns to agriculture and fisheries are jointly maximized, taking into account the effect of flooding depth and timing on production, and value of catch in markets and for subsistence nutrition. Results for a region in Bangladesh show that optimal production in a natural floodplain yields higher net returns compared with a floodplain modified by flood control structures. This finding implies that neglecting the bio-economic relationship between fisheries and land use may significantly affect the long-run economic role of a river floodplain, particularly where subsistence consumption is important to social welfare.
Polarcauste: law, justice and the Shoah in French detective fiction
Authors: Fraser David
Published: January 2006

The Holocaust sits uncomfortably within general theories of representation. Moreover, the Shoah also raises fundamental problems for our understandings of law and justice within modernity. ‘After Auschwitz’ serves as both a temporal and epistemological signifier within and about law and justice within modernity. This article studies the ways in which a new literary genre of French detective fiction, the néo-polar, which emerged after events of May 1968, has posited new understandings of law, justice and memory of the Shoah. Drawing on the Frankfurt School of Critical Theory and deconstruction, the article argues that the new generation of French writers problematise law, justice and politics through a genre in which ‘fiction’ writes and re-writes history and memory in a search for an impossible justice.
Comparison of four models to determine surface soil moisture from C‐band radar imagery in a sparsely vegetated semiarid landscape
Authors: Thoma D. P. , Moran M. S. , Bryant R. , Rahman M. , Holifield‐Collins C. D. , Skirvin S. , Sano E. E. , Slocum K.
Published: January 2006

Four approaches for deriving estimates of near‐surface soil moisture from radar imagery in a semiarid, sparsely vegetated rangeland were evaluated against in situ measurements of soil moisture. The approaches were based on empirical, physical, semiempirical, and image difference techniques. The empirical approach involved simple linear regression of radar backscatter on soil moisture, while the integral equation method (IEM) model was used in both the physical and semiempirical approaches. The image difference or delta index approach is a new technique presented here for the first time. In all cases, spatial averaging to the watershed scale improved agreement with observed soil moisture. In the empirical approach, variation in radar backscatter explained 85% of the variation in observed soil moisture at the watershed scale. For the physical and best semiempirical adjustment to the physical model, the root‐mean‐square errors (RMSE) between modeled and observed soil moisture were 0.13 and 0.04, respectively. Practical limitations to obtaining surface roughness measurements limit IEM utility for large areas. The purely image‐based delta index has significant operational advantage in soil moisture estimates for broad areas. Additionally, satellite observations of backscatter used in the delta index indicated an approximate 1:1 relationship with soil moisture that explained 91% of the variability, with RMSE = 0.03. Results showed that the delta index is scaled to the range in observed soil moisture and may provide a purely image based model. It should be tested in other watersheds to determine if it implicitly accounts for surface roughness, topography, and vegetation. These are parameters that are difficult to measure over large areas, and may influence the delta index.
Comparison of definitions of Indian summer monsoon onset: Better representation of rapid transitions of atmospheric conditions
Authors: Taniguchi Kenji , Koike Toshio
Published: January 2006

Onset of the Indian Summer Monsoon (ISM) has been defined by various methods, but it is uncertain which definition is most adequate. Focusing on the rapid transition of atmospheric conditions and correspondence with rainfall from 1997 to 2004, we compare the representativeness of ISM onset described by three variables spatially averaged over the Arabian Sea. Though integrated water vapor significantly increases, it cannot detect the beginning of the rainy season. Moisture transport shows rapid increase, and represents the abrupt transition of atmospheric conditions. However, it sometimes fails to determine the start of monsoon rainfall. Rapid enhancement of the low‐level wind speed shows good agreement with the abrupt beginning of the rainy season, and it represents the clear transition in atmospheric fields. The onset criterion based on the wind speed is easier, clearer, and successfully screens out “Bogus onset”, and is therefore more suitable to define the ISM onset.
Formation and decay of the spring warm pool in the South China Sea
Authors: Wang Weiqiang , Wang Chunzai
Published: January 2006

As part of the southeast Asian monsoon system, the South China Sea (SCS) is characterized by monsoon wind transition from northeasterly to southwesterly in the boreal spring. Correspondingly, a spring warm pool (SWP) with mixed layer temperature warmer than 29°C is formed and peaked in May over the central SCS and then decays in June. Calculations of the heat budget showed that the surface heat flux and ocean dynamics have different roles in the formation and decay of the SWP. The surface heat flux is found to play a dominant role for the formation of the SWP in May. The onset of the southwest monsoon corresponds to an increase in cloudiness and rainfall and a strong wind speed in the SCS that decrease the surface heat flux in June. Moreover, the onset of the southwest monsoon also changes oceanic circulation pattern that advects cold water from the northwest to the southeast and pumps cold water into the upper mixed layer. These cooling effects overcome the warming effect of the surface heat flux, resulting in the decay of the SWP in June.
Permeability‐porosity relationship: A reexamination of the Kozeny‐Carman equation based on a fractal pore‐space geometry assumption
Authors: Costa Antonio
Published: January 2006

The relationship between permeability and porosity is reviewed and investigated. The classical Kozeny‐Carman approach and a fractal pore‐space geometry assumption are used to derive a new permeability‐porosity equation. The equation contains only two fitting parameters: a Kozeny coefficient and a fractal exponent. The strongest features of the model are related to its simplicity and its capability to describe measured permeability values of different non‐granular porous media better than other models.
Simplifying the interaction of land surfaces with radiation for relating remote sensing products to climate models
Authors: Pinty B. , Lavergne T. , Dickinson R. E. , Widlowski J.‐L. , Gobron N. , Verstraete M. M.
Published: January 2006

Remote sensing products, such as the fraction of reflected solar radiation flux, as well as the amount of radiation absorbed in the photosynthetically active spectral region and the Leaf Area Index (LAI), are operationally available from Space Agencies. Climate models may benefit from these products provided their one dimensional (1‐D) radiation transfer schemes effectively represent the three dimensional (3‐D) effects implied by the internal spatial variability of vegetation canopies, e.g., the leaf area density, at all scales and resolutions involved (say from 1 to 100 kilometers). Failing to do so leads to inherent inconsistencies between the domain‐averaged reflected and absorbed fluxes, and the implied Leaf Area Index. We propose a comprehensive approach which introduces a parameterization of the internal variability of the LAI in the 1‐D representation of the radiation scheme, called a domain‐averaged structure factor, and provides a description of the radiant fluxes fully consistent with the LAI specified by remote sensing. We take this opportunity to revisit and update the two‐stream formulations implemented in climate models to accurately estimate the fractions of radiation absorbed separately by the vegetation canopy and the underlying surface. This is achieved by isolating the contributions of the vegetation canopy alone, the background as seen through the canopy gaps and the multiple scattering between the vegetation layer and the background. The performance of this formulation is evaluated against results from Monte Carlo simulations relative to explicit realistic 3‐D canopies to show that the proposed scheme correctly simulates both the amplitude and the angular variations of all radiant fluxes with respect to the solar zenith angle.
A climatological‐dynamical analysis associated with precipitation around the southern part of the Himalayas
Authors: Bhatt B. C. , Nakamura K.
Published: January 2006

The precipitation variability and circulation characteristics around the Himalayas are examined using the Tropical Rainfall Measuring Mission (TRMM) data, the Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) reanalysis, National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP‐NCAR) reanalysis, and some of the Indian radiosonde data sets. The observation by precipitation radar on board the TRMM satellite reveals an afternoon maximum of precipitation during the premonsoon season and midnight–early morning maximum during the summer monsoon season over the southern slopes of the Himalayas. The data also shows that the morning precipitation moves southward in the mature monsoon season. The GAME reanalysis reveals a robust diurnal cycle of the atmospheric system that is coherent with the diurnal cycle of precipitation around the southern slopes of the Himalayas. The significant increase of moisture due to the southeasterly wind in the mature monsoon season seems to produce favorable conditions for the midnight–early morning rain. The down‐valley wind at midnight probably triggers moist convection. The radiative cooling at the top of clouds may enhance the convection. The precipitation associated with the moist convection seems to generate a cold pool, which results in a density current. The downslope movement of the density current probably induces the southward movement of the precipitation system in the morning.
Extreme cold air outbreaks over the United States, the polar vortex, and the large‐scale circulation
Authors: Cellitti Michael P. , Walsh John E. , Rauber Robert M. , Portis Diane H.
Published: January 2006

Extreme cold air outbreaks (CAOs) affect a large region of the midlatitudes during the winter months. An objective criterion was developed for identifying and ranking the 30 most extreme CAOs over the eastern United States using observational surface temperatures for November–March 1948–2002. A composite of these events shows that the tropospheric polar vortex is weaker than average prior to CAO onset, while the vortex strengthens following CAO onset. There is also very little correlation between the strength of the polar vortex and the intensity of CAOs. These results suggest that the polar vortex is generally not a useful forecasting tool by itself in predicting the timing and severity of a CAO event. Additionally, other large‐scale circulation features were examined to see whether CAO events occur in response or subsequent to teleconnection anomalies over the North Pacific and North Atlantic. It was found that the North Atlantic Oscillation (NAO) is negative prior to onset of the composite CAO but becomes positive approximately 5 days after onset. This suggests that there is some predictability in the Atlantic and European weather during CAOs on timescales of 3 to 6 days. The Pacific–North American (PNA) teleconnection pattern becomes increasingly positive during onset of the composite CAO. Even though the largest 500 mb height anomalies in the composite CAO do not align closely with the nodes of the PNA pattern, the deepening of the 500 mb trough over the eastern United States following CAO onset appears to be directly responsible for the increase in the composite PNA.
Geomorphic control of landscape carbon accumulation
Authors: Rosenbloom Nan A. , Harden Jennifer W. , Neff Jason C. , Schimel David S.
Published: January 2006

We use the CREEP process‐response model to simulate soil organic carbon accumulation in an undisturbed prairie site in Iowa. Our primary objectives are to identify spatial patterns of carbon accumulation, and explore the effect of erosion on basin‐scale C accumulation. Our results point to two general findings. First, redistribution of soil carbon by erosion results in a net increase in basin‐wide carbon storage relative to a noneroding environment. Landscape‐average mean residence times are increased in an eroding landscape owing to the burial/preservation of otherwise labile C. Second, field observations taken along a slope transect may overlook significant intraslope variations in carbon accumulation. Spatial patterns of modeled deep C accumulation are complex. While surface carbon with its relatively short equilibration time is predictable from surface properties, deep carbon is strongly influenced by the landscape's geomorphic and climatic history, resulting in wide spatial variability. Convergence and divergence associated with upland swales and interfluves result in bimodal carbon distributions in upper and mid slopes; variability in carbon storage within modeled mid slopes was as high as simulated differences between erosional shoulders and depositional valley bottoms. The bimodality of mid‐slope C variability in the model suggests that a three‐dimensional sampling strategy is preferable over the traditional two‐dimensional analog or “catena” approach.
Pharmacological characterization of muscarinic receptor subtypes mediating vasoconstriction of human umbilical vein
Authors: Pujol Lereis Virginia Andrea , Hita Francisco Javier , Gobbi Mauro Darío , Verdi Marcela Gomez , Rodriguez María Cecilia , Rothlin Rodolfo Pedro
Published: January 2006

The present study attempted to pharmacologically characterize the muscarinic receptor subtypes mediating contraction of human umbilical vein (HUV).

HUV rings were mounted in organ baths and concentration–response curves were constructed for acetylcholine (ACh) (pEC50: 6.16±0.04; maximum response 80.00±1.98% of the responses induced by serotonin 10 μM). The absence of endothelium did not modify the contractile responses of ACh in this tissue.

The role of cholinesterases was evaluated: neither neostigmine (acetylcholinesterase inhibitor) nor iso‐OMPA (butyrylcholinesterase inhibitor) modified ACh responses. When both enzymes were simultaneously inhibited, a significantly but little potentiation was observed (control: pEC506.33±0.03; double inhibition: pEC506.57±0.05).

Atropine, nonselective muscarinic receptors antagonist, inhibited ACh‐induced contraction (pKB9.67). The muscarinic receptors antagonists pirenzepine (M1), methoctramine (M2) and pFHHSiD (M3) also antagonized responses to ACh. The affinity values estimated for these antagonists against responses evoked by ACh were 7.58, 6.78 and 7.94, respectively. On the other hand, PD 102807 (M4selective muscarinic receptors antagonist) was ineffective against ACh‐induced contraction.

In presence of a blocking concentration of pirenzepine, pFHHSiFD produced an additional antagonism activity on ACh‐induced responses.

The M1muscarinic receptors agonist McN‐A‐343 produced similar maximum but less potent responses than ACh in HUV. The calculated pA2for pirenzepine against McN‐A‐343 induced responses was 8.54.

In conclusion, the data obtained in this study demonstrate the role of M1muscarinic receptor subtypes and suggest the involvement of M3muscarinic receptor subtypes in ACh‐induced vasoconstriction in HUV rings. In addition, the vasomotor activity evoked by ACh does not seem to be modulated by endothelial factors, and their enzymatic degradation appears to have little functional relevance in this tissue.

British Journal of Pharmacology(2006)147, 516–523. doi:10.1038/sj.bjp.0706654
Activation of nicotinic ACh receptors with α4 subunits induces adenosine release at the rat carotid body
Authors: Conde Sílvia V , Monteiro Emília C
Published: January 2006

The effect of ACh on the release of adenosine was studied in rat whole carotid bodies, and the nicotinic ACh receptors involved in the stimulation of this release were characterized.

ACh and nicotinic ACh receptor agonists, cytisine, DMPP and nicotine, caused a concentration‐dependent increase in adenosine production during normoxia, with nicotine being more potent and efficient in stimulating adenosine release from rat CB than cytisine and DMPP.

D‐Tubocurarine, mecamylamine, DHβE and α‐bungarotoxin, nicotinic ACh receptor antagonists, caused a concentration‐dependent reduction in the release of adenosine evoked by hypoxia. The rank order of potency for nicotinic ACh receptor antagonists that inhibit adenosine release was DHβE>mecamylamine>D‐tubocurarine>α‐bungarotoxin.

The effect of the endogenous agonist, ACh, which was mimicked by nicotine, was antagonized by DHβE, a selective nicotinic receptor antagonist.

The ecto‐5′‐nucleotidase inhibitor AOPCP produces a 72% inhibition in the release of adenosine from CB evoked by nicotine.

Taken together, these data indicate that ACh induced the production of adenosine, mainly from extracellular ATP catabolism at the CB through a mechanism that involves the activation of nicotinic receptors with α4 and β2 receptor subunits.

British Journal of Pharmacology (2006) 147, 783–789. doi:10.1038/sj.bjp.0706676
On the unsteady-state species separation of a binary liquid mixture in a rectangular thermogravitational column
Authors: Haugen Kjetil B. , Firoozabadi Abbas
Published: January 2006

This paper investigates the unsteady-state species segregation of binary liquid mixtures in rectangular thermogravitational columns. The analysis leads to a procedure to obtain both molecular and thermal diffusion coefficients from transient separation measurements. Two models are presented: first, an ideal model where buoyancy only depends on temperature and second, a general model where buoyancy also varies with composition. Steady-state measurements are not required regardless of which model is chosen. As a result, the new procedure is faster than steady-state procedures. When either the molecular or thermal diffusion coefficient is known a priori, the other can be obtained without knowledge of fluid properties such as density, viscosity, thermal expansion, and compositional coefficients.
Using simultaneous diagonalization and trace minimization to make an efficient and simple multidimensional basis for solving the vibrational Schrödinger equation
Authors: Dawes Richard , Carrington Tucker
Published: January 2006

In this paper we improve the product simultaneous diagonalization (SD) basis method we previously proposed [J. Chem. Phys. 122, 134101 (2005)] and applied to solve the Schrödinger equation for the motion of nuclei on a potential surface. The improved method is tested using coupled complicated Hamiltonians with as many as 16 coordinates for which we can easily find numerically exact solutions. In a basis of sorted products of one-dimensional (1D) SD functions the Hamiltonian matrix is nearly diagonal. The localization of the 1D SD functions for coordinate qc depends on a parameter we denote αc. In this paper we present a trace minimization scheme for choosing αc to nearly block diagonalize the Hamiltonian matrix. Near-block diagonality makes it possible to truncate the matrix without degrading the accuracy of the lowest energy levels. We show that in the sorted product SD basis perturbation theory works extremely well. The trace minimization scheme is general and easy to implement.
Inequivalent quantizations of the N=3 Calogero model with scale and mirror-S3 symmetry
Authors: Yonezawa Nobuhiro , Tsutsui Izumi
Published: January 2006

We study the inequivalent quantizations of the N=3 Calogero model by separation of variables, in which the model decomposes into the angular and the radial parts. Our inequivalent quantizations respect the “mirror-S3” invariance (which realizes the symmetry under the cyclic permutations of the particles) and the scale invariance in the limit of vanishing harmonic potential. We find a two-parameter family of novel quantizations in the angular part and classify the eigenstates in terms of the irreducible representations of the S3 group. The scale invariance restricts the quantization in the radial part uniquely, except for the eigenstates coupled to the lowest two angular levels for which two types of boundary conditions are allowed independently from all upper levels. It is also found that the eigenvalues corresponding to the singlet representations of the S3 are universal (parameter-independent) in the family, whereas those corresponding to the doublets of the S3 are dependent on one of the parameters. These properties are shown to be a consequence of the spectral preserving SU(2) (or its subgroup U(1)) transformations allowed in the family of inequivalent quantizations.
Geometric and electronic structures of metal-substitutional fullerene C59Sm and metal-exohedral fullerenes C60Sm
Authors: Lu Gongli , Deng Kaiming , Wu Haiping , Yang Jinlong , Wang Xin
Published: January 2006

The geometric and electronic structures of metal-substituted fullerene C59Sm and exohedral fullerenes C60Sm are studied using the density-functional theory. The geometric optimization shows that the replacement of a C atom with a Sm in C60 yields a stable substitutionally doped fullerene C59Sm, and among the five possible optimized geometries for C60Sm, the most favorable exohedral sites are above the center of a hexagon and a pentagon ring. The calculations for electronic structures show that the magnetic moment of Sm is preserved for all the stable structures as tiny hybridization takes place between the orbitals of the Sm atom and those of their neighboring carbons. Because of the small energy gaps and the half occupation of the highest occupied molecular orbitals, all the stable C60Sm isomers are inferred to be conductors.
Structural characterizations and electronic properties of Ti-doped SnO2(110) surface: A first-principles study
Authors: Lin Wei , Zhang Yong-Fan , Li Yi , Ding Kai-Ning , Li Jun-Qian , Xu Yi-Jun
Published: January 2006

The Ti-doped SnO2(110) surface has been investigated by using first-principles method with a slab model. The geometrical optimizations and band-structure calculations have been performed for four possible doping models. Our results indicate that the substitution of Ti for sixfold-coordinated Sn atom at the top layer is most energetically favorable. Compared to the undoped surface, those Sn and O atoms located above Ti atom tend to move toward the bulk side. Besides the surface relaxations, the doping of Ti has significant influences on the electronic structures of SnO2(110) surface, including the value and position of minimum band gap, the components of valence and conduction bands, the distributions of the charge densities, and the work function of the surface. Furthermore, the effects introduced by the substitution of Ti atom observed in the experiments can be well explained when the sixfold-coordinated Sn atom at the first layer is replaced by Ti atom.
Defects-enhanced dissociation of H2 on boron nitride nanotubes
Authors: Wu Xiaojun , Yang Jinlong , Hou J. G. , Zhu Qingshi
Published: January 2006

With the density-functional theory and nudged elastic band method, the adsorption and dissociation of the hydrogen molecule on the boron nitride (BN) nanotubes with and without defects are studied theoretically. Hydrogen molecule physically adsorbs on the surface of the BN layer and nanotubes. The dissociation of the hydrogen molecule on the surface of the perfect BN layer and nanotubes is endothermic, and the energy barrier reduces with the decrease of the diameter of the tubes, while it is still larger than 2.0 eV for the (7,0) BN nanotube. Antisite, carbon substitutional, vacancy, and Stone-Wales 5775 defects on the wall of the tube are considered. With the presence of the defects, the dissociation of the hydrogen molecule becomes exothermic and the dissociation barrier can be reduced to about 0.67 eV.
Structures and relative stability of medium-sized silicon clusters. IV. Motif-based low-lying clusters Si21–Si30
Authors: Yoo Soohaeng , Zeng X. C.
Published: January 2006

Structures and relative stability of four families of low-lying silicon clusters in the size range of Sin(n=21–30) are studied, wherein two families of the clusters show prolate structures while the third one shows near-spherical structures. The prolate clusters in the first family can be assembled by connecting two small-sized magic clusters Sin (n=6, 7, 9, or 10) via a fused-puckered-hexagonal-ring Si9 unit (a fragment of bulk diamond silicon), while those in the second family can be constructed on the basis of a structural motif consisting of a puckered-hexagonal-ring Si6 unit (also a fragment of bulk diamond silicon) and a small-sized magic cluster Sin (n=6, 7, 9, or 10). For Si21–Si29, the predicted lowest-energy clusters (except Si27) exhibit prolate structures. For clusters larger than Si25, the third family of near-spherical clusters becomes energetically competitive. These near-spherical clusters all exhibit endohedral cagedlike structures, and the cages are mostly homologue to the carbon-fullerene cages which consist of pentagons and hexagons exclusively. In addition, for Si26–Si30, we construct a new (fourth) family of low-lying clusters which have “Y-shaped” three-arm structures, where each arm is a small-sized magic cluster (Si6,Si7, or Si10). Density-functional calculation with the B3LYP functional shows that this new family of clusters is also energetically competitive, compared to the two prolate and one near-spherical low-lying families.
Nanosecond rapid freezing of liquid benzene under shock compression studied by time-resolved coherent anti-Stokes Raman spectroscopy
Authors: Matsuda Akitaka , Kondo Ken-ichi , Nakamura Kazutaka G.
Published: January 2006

Nanosecond time-resolved coherent anti-Stokes Raman spectroscopy is used to investigate the shock-induced liquid-solid phase transition and crystallization of liquid benzene. Temporal evolution of the Raman shift of the ring-breathing and C–H stretching modes is investigated. A metastable supercompressed state and a liquid-solid phase transition are observed under shock compression. Time-resolved Raman spectra reveal that the liquid state is initially a metastable state and rapidly transforms to the solid state within 25ns under shock compression at 4.2GPa.
Covariant kinetic dispersion theory of linear transverse waves parallel propagating in magnetized plasmas with thermal anisotropy
Authors: Lazar M. , Schlickeiser R.
Published: January 2006

The properties of transverse waves parallel propagating in magnetized plasmas with arbitrary composition and thermally anisotropic, are investigated on the basis of relativistic Vlasov-Maxwell equations. The transverse dispersion relations for plasmas with arbitrary distribution functions are derived. These dispersion relations describe the linear response of the system to the initial perturbations and thus define all existing linear (transverse) plasma modes in the system. By analytic continuation the dispersion relations in the whole complex frequency plane are constructed. Further analysis is restricted to the important case of anisotropic bi-Maxwellian equilibrium plasma distribution functions. Explicit forms of the relativistically correct transverse dispersion relations are derived that hold for any values of the plasma temperatures and the temperature anisotropy. In the limit of nonrelativistic plasma temperatures the dispersion relations are expressed in terms of plasma dispersion function, however, the dependence on frequency and wave numbers is markedly different from the standard noncovariant nonrelativistic analysis. Only in the strictly unphysical formal limit of an infinitely large speed of light, c→∞, does the nonrelativistic dispersion relations reduce to the standard noncovariant dispersion relations.
Diverging ion motion in an inertial electrostatic confinement discharge
Authors: Shrier O. , Khachan J. , Bosi S. , Fitzgerald M. , Evans N.
Published: January 2006

An inertial electrostatic confinement device operating in the gaseous discharge pressure regime (units to tens of mTorr) is shown to consist of a substantial flux of neutrals diverging from the cathode center. Using Doppler shift spectroscopy, it is shown that directional ion beams, originating from the center, increase in energy as they move away from the center. Moreover, through charge exchange, these ions become energetic neutrals and travel out of the cathode to the anode. Although naturally there are converging ions, it is shown that this is a lesser component of the energetic particle beams in this pressure range.
Catalyst-free pulsed-laser-deposited ZnO nanorods and their room-temperature photoluminescence properties
Authors: Liu Z. W. , Ong C. K. , Yu T. , Shen Z. X.
Published: January 2006

ZnO nanorods with various diameters were synthesized on both sapphire and silicon substrates by a pulsed-laser-deposition technique without a catalyst using relatively high background oxygen pressure (5–20 Torr) and substrate temperature (550 °C-700 °C). The photoluminescence (PL) properties of the nanorods were investigated. The difference in PL emission intensity for the samples produced at various oxygen pressures has been attributed to the size difference and surface status of the nanorods. The increased deep level emission with increasing temperature resulted from the size difference and increasing oxygen evaporating. The effect of substrate nature on the PL property has also been investigated.
Microscopic model for dielectric constant in metal-insulator-metal capacitors with high-permittivity metallic oxides
Authors: Bécu Stéphane , Crémer Sébastien , Autran Jean-Luc
Published: January 2006

A microscopic model for metal-insulator-metal (MIM) capacitors with high permittivity metallic oxides is developed to determine the electric field dependence of dielectric constant. The model indicates that the metallic cation displacement in the tetrahedral cell is at the origin of the dielectric constant variations. The temperature dependence has also been included to compare the model with experiment and to give an indication of the reliability of the model. The experimental data that are compared to our model have been obtained from capacitance versus voltage (C-V) characterization on MIM capacitors with alumina as dielectric and TiN electrodes. The C-V curves have been performed at a frequency of 100kHz for different temperatures ranging from 200to400K.
Comparative studies of CO and H2O interactions with Pd(111) surface: A theoretical study of poisoning
Authors: Alfonso Dominic R.
Published: January 2006

Detailed density functional theory calculations were carried out to investigate the adsorption and dissociation of CO and H2O on Pd(111). The bonding of CO on the surface is found to be stronger that H2O. This finding does not support the previous suggestion that the stronger poisoning effect displayed by H2O on a Pd membrane, in comparison to CO, is due its higher binding energy. Instead, our results show that dissociation of H2O is a more facile process compared to CO. The dissociation of H2O gives rise to adsorbed O which is a better poison than CO.
Quantum-cascade lasers operating in continuous-wave mode above 90°C at λ∼5.25μm
Authors: Evans A. , Nguyen J. , Slivken S. , Yu J. S. , Darvish S. R. , Razeghi M.
Published: January 2006

We report on the design and fabrication of λ∼5.25μm quantum-cascade lasers (QCLs) for very high temperature continuous-wave (cw) operation. Cw operation is reported up to a maximum temperature of 90°C (363K). Cw output power is reported in excess of 500mW near room temperature with a low threshold current density of 1.4kA∕cm2 at 298K. Room temperature average power of over 540mW is reported at 50% duty cycle. A high thermal conductance (Gth) of 340W∕Kcm2 is reported for cw QCLs. A finite element thermal model is used to investigate the Gth and maximum cw operating temperature of the QCLs.
Integrated structural and functional optical imaging combining spectral-domain optical coherence and multiphoton microscopy
Authors: Vinegoni Claudio , Ralston Tyler , Tan Wei , Luo Wei , Marks Daniel L. , Boppart Stephen A.
Published: January 2006

An integrated microscope that combines different optical techniques for simultaneous imaging is demonstrated. The microscope enables spectral-domain optical coherence microscopy based on optical backscatter, and multiphoton microscopy for the detection of two-photon fluorescence and second harmonic generation signals. The unique configuration of this integrated microscope allows for the simultaneous acquisition of both anatomical (structural) and functional imaging information with particular emphasis for applications in the fields of tissue engineering and cell biology. In addition, the contemporary analysis of the spectroscopic features can enhance contrast by differentiating among different tissue components.
Observation of [110] surface band within {101} a-domain of heteroepitaxial PbTiO3 thin film fabricated by hydrothermal epitaxy
Authors: Choi S. K. , Ahn S. H. , Jung W. W. , Park J. C. , Song S. A. , Lim C. B. , Cho Yasuo
Published: January 2006

Heteroepitaxial PbTiO3 film on an Nb-doped (001) cubic SrTiO3 substrate was fabricated by hydrothermal epitaxy at 200°C. Piezoresponse force microscopy and x-ray Θ rocking curves confirmed that the film showed a c∕a∕c∕a multi-domain structure even though it did not undergo a cubic paraelectric (PE) to tetragonal ferroelectric (FE) phase transition. After heat treatment of this film at 600°C, we observed the [110] surface band within the a-domain, which was formed through the PE to FE phase transition. We also found that a [110] surface band existed along the (11¯1) plane within the a-domain. We predicted that the [110] surface band would be monoclinic phase due to the interaction of two different variants of a-domains in the presence of a c-domain in the heteroepitaxial PbTiO3 film.
Variable liquid crystal pretilt angles by nanostructured surfaces
Authors: Yeung Fion S. , Ho Jacob Y. , Li Y. W. , Xie F. C. , Tsui Ophelia K. , Sheng P. , Kwok H. S.
Published: January 2006

Variable liquid crystal pretilt angles of any value from 0 to 90° can be obtained by using a nanostructured alignment layer. This layer is robust and reliable. The pretilt angles obtained are stable against high storage and operating temperatures, and have strong anchoring energies.
Atomistic simulation of amorphization thermokinetics in lanthanum pyrozirconate
Authors: Crocombette Jean-Paul , Chartier Alain , Weber William J.
Published: January 2006

The kinetics of amorphization in La2Zr2O7 pyrochlore is investigated using molecular dynamics simulations. Irradiation damage is simulated by continuous accumulation of cation Frenkel pairs at various temperatures. As observed experimentally, La2Zr2O7 first transitions to the fluorite structure, independent of the temperature, and amorphization occurs at low temperatures. A model fit of the simulated dose-temperature curve reproduces experimental results in the literature, with a low temperature amorphization dose D0=1.1 displacement per cation and an activation energy Eact=0.036eV. Present simulations indicate that point defect recombination can control the temperature dependence of amorphization driven by point defect accumulation.
Superconductor-semiconductor magnetic microswitch
Authors: Castellana C. , Giazotto F. , Governale M. , Taddei F. , Beltram F.
Published: January 2006

A hybrid superconductor-two-dimensional electron gas microdevice is presented. Its working principle is based on the suppression of Andreev reflection at the superconductor-semiconductor interface caused by a magnetic barrier generated by a ferromagnetic strip placed on top of the structure. Device switching is predicted with fields up to some mT and working frequencies of several GHz, making it promising for applications ranging from microswitches and storage cells to magnetic field discriminators.
Fiscal Policy and Self-Employment: Targeting Business Growth
Authors: Sloan Brian , Chittenden Francis
Published: January 2006

The small-business sector is the breeding ground of new businesses, but distinguishing those firms that wish to grow from the hundreds of thousands of lifestyle firms is difficult. Studies suggest very few small firms seek growth, and fiscal policies aimed at promoting business growth could be misdirected in the belief that the ambition to grow is widespread in this part of the economy. The small-firm sector is dominated by the self-employed and an important classification is the large numbers of ‘own-account self-employed‘. It is unclear to what extent these people should be classified as true ‘business owners‘. Using face-to-face interviews, the authors explore the motivations for becoming self-employed and the growth aspirations of self-employed people. Based on the outcomes, suggestions are made about how fiscal policy might be targeted to improve neutrality and promote business growth.
A New Conceptualisation of Business Development for SMEs: A Focus on Development Potential
Authors: Massey Claire
Published: January 2006

Despite an increase in the amount of research on the programmes that many governments around the world are using to guide firm development, develop managerial capability, and encourage firms into undertaking practices that will result in improved performance, there is no agreement within the research community on an appropriate way of conceptualising the task of ‘business development’ or of designing specific developmental programmes. Instead, there is a plethora of frameworks that categorise the overall policies and the programmes in terms of: the service they deliver (for example, ‘hard’ or ‘soft’ programmes); the target group (for example, women, ethnic groups, older or younger people); or by the outcome they wish to achieve (for example, the development of export capability).

Although they are useful from an operational perspective, that is, from the perspective of a policymaker faced with the task of allocating scarce resources, these approaches do little to address a critical aspect of business development that is especially evident in small firms: the interrelatedness of the firm and its owner. After reviewing the available frameworks, and discussing the problems of operationalising them, the author presents a new framework and demonstrates its use by applying it to the case of New Zealand. This framework is based on two dimensions: the development potential of the firm and the development potential of the individual—an approach that has hitherto not been used, despite the recognition of the interrelatedness of the firm and the individual, especially in countries where there are large numbers of micro enterprises. The framework contributes to the ongoing debate on the design of effective developmental programmes by enabling policymakers to focus on the key issues—developmental potential—rather than simply on the individual's membership of a specific target group.
The Effect of the National Minimum Wage on the UK Small Business Sector: A Geographical Analysis
Authors: Mason Colin M , Carter Sara , Tagg Stephen K
Published: January 2006

A national minimum wage (NMW) was introduced into the United Kingdom in 1999 as part of New Labour's active labour-market approach. The level has been uprated on several occasions since then. Most research suggests that the NMW has benefited low-paid workers while having little adverse impact on employment levels. This paper explores the regional impact of the NMW on the small business sector, using data from the Federation of Small Businesses' biennial survey, the largest business survey in the United Kingdom. Overall, just over 21% of businesses with employees uprated employees and just under 10% of employees have benefited from pay uprates. The impact has varied across industries, with the greatest effects in the hotels and catering sector. In general, affected businesses have anticipated that they would be able to absorb the costs, although in some cases at the expense of a slight decline in profitability. The impact of the NMW also varies across the regions, having the least impact in London and the South East and the greatest impact in the ‘north‘. In the northern regions, businesses are less able to absorb the increased costs and more likely to respond by increasing prices. This has potential implications for the competitiveness of small and medium-sized enterprises in these regions, which is more likely to be based around price and cost advantages than their counterparts in the south. The Low Pay Commission therefore should give greater attention to the geographical impacts of the NMW in its evaluation and when proposing future increases in the rate.
UK Vietnamese Businesses: Cultural Influences and Intracultural Differences
Authors: Bagwell Susan
Published: January 2006

Current UK policy views the encouragement of enterprise by black and minority ethnic (BME) communities as a key strategy of both its social inclusion and its competitiveness agenda. However, the evidence suggests that the take-up of business support by these groups is very limited, and recent research has argued for the need for more culturally sensitive provision and a better understanding of the diverse needs of different BME groups. This paper reports on a study of first-generation and second-generation Vietnamese businesses in London, designed to explore traditional cultural influences on business practice. The results suggest that, as with many other ethnic groups, attitudes towards the family, trust, and language have a key impact on the start-up and operation of the businesses. However, this study suggests that the ways in which these three factors impinge on business practice vary between the older first generation (the original ‘boat people‘), the UK-educated second generation, and younger more recent immigrants, and is also mediated by sectoral influences, the pressures of the marketplace, and the degree of family involvement in the business. In particular second-generation and recent immigrants were less likely to adopt traditional collectivist approaches to the running of their business compared with the first generation, but their business practice was still often influenced by strong family loyalties. The author argues that theories of ethnic minority enterprise that advocate a mixed-embeddedness approach need to incorporate an historical dimension. The findings emphasize the need for enterprise-support policy to take account not only of intercultural differences, but also the intracultural differences that exist within different ethnic minority groups. The author makes a number of suggestions as to how policy and practice should be adapted accordingly.
Regional Renaissance? New Forms of Governance in Nonmetropolitan Australia
Authors: Everingham Jo-Anne , Cheshire Lynda , Lawrence Geoffrey
Published: January 2006

Since the Second World War, Australian governments have adopted various approaches to governing nonmetropolitan Australia. The authors profile three distinct approaches to governance characterised as (1) state-centred regionalism; (2) new localism; and (3) new forms of multifaceted regionalism. Although recent policy initiatives have been justified by the argument that the region is the most suitable scale for planning and development in nonmetropolitan Australia, in practice the institutional landscape is a hybrid of overlapping local, regional, and national scales of action. The authors compare this new, multifaceted, regionalism with the so-called ‘new regionalism’ currently being promoted in Western Europe and North America. It is argued that new regionalism differs in quite important ways from the regionalism currently being fostered in Australia. In Australia, the centrality of sustainability principles, and the attempt to foster interdependence amongst stakeholders from the state, market, and civil society, have produced a layer of networked governance that is different from that overseas. It is argued that there is a triple bottom-line ‘promise’ in the Australian approach which differs from the Western Europe/North American model, and which has the potential to deliver enhanced economic, social, and environmental outcomes.