bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflecting on the next generation of models for community-based natural resources management
Authors: SHACKLETON C.M. , WILLIS T.J. , BROWN K. , POLUNIN N.V.C.
Published: June 2010

Community-based natural resource management (CBNRM) has been a pervasive paradigm in conservation circles for three decades. Despite many potentially attractive attributes it has been extensively critiqued from both ecological and sociological perspectives with respect to theory and practice (for example Leach et al. 1999; Berkes 2004; Fabricius et al. 2004; Blaikie 2006). Nonetheless, many successful examples exist, although an equal number have seemingly not met expectations. Is this because of poor implementation or rather a generally flawed model? If the criteria and conditions for success are so onerous that relatively few projects or situations are likely to qualify, what then is the value of the model? The questions thus become: how and what can we learn from the past theory and practice to develop a new generation of flexible, locally responsive and implementable CBNRM models, and what are likely to be the attributes of such models?
Rapid and continued population decline in the Spoon-billed Sandpiper Eurynorhynchus pygmeus indicates imminent extinction unless conservation action is taken
Authors: ZÖCKLER CHRISTOPH , SYROECHKOVSKIY EVGENY E. , ATKINSON PHILIP W.
Published: June 2010

The Spoon-billed Sandpiper Eurynorhynchus pygmeus (IUCN Category: Critically Endangered) is in rapid decline. Data from across the entire breeding range (Chukotka and Koryakya in the Russian far north-east) and especially from the well-studied southern core breeding area at Meinypilgyno, confirm the continuing strong decline. At four breeding sites, where more than two counts were available for analysis, the decline was estimated at 26% per annum between 2002 and 2009, or an 88% decline over this period. Allowing for unsurveyed areas, this equates to a decline from a total population of approximately 1,000 breeding pairs in 2000 to 120–220 in 2009. Breeding studies at Meinypilgyno in 2003–2007 (not 2006) showed that the proportion of nests hatching at least one chick was 0.65 and once chicks left the nest, the mean brood size of chicks up to one week old was 1.99. Where it was possible to follow broods, 0.61 chicks fledged per nesting attempt. Survival and recruitment analysis of birds ringed at Meinypilgyno indicated that annual adult survival did not significantly differ over the 2003–2009 study but that recruitment in to the adult breeding population was effectively zero in all but one year of the study (2005). Resighting data for the last two years of the study were sparse due to very low numbers of marked adults being recorded and survival rates over the last 2–3 years of the study must therefore be treated with caution. The analysis therefore indicated that after fledging, survival during immaturity must be very low, leading to a low (or no) recruitment into an ageing population. Recent observations collated from the non-breeding areas confirm the declining trend observed in the breeding areas and imply that the main threats to the population lie along the migration route or in the wintering areas. These are poorly known although hunting in the wintering areas has been identified as a major mortality factor. Other threats include major loss of their intertidal habitats, and collection of birds on the breeding areas by specimen collectors. Improved monitoring in both the breeding and non-breeding areas as well as research on juvenile survival is recommended. Concerted international conservation action is essential if this species is to avoid extinction. This requires (i) improved understanding of the main wintering and staging areas and associated threats; (ii) addressing those threats that can be tackled with immediate effect, such as hunting; (iii) continued long-term monitoring on the breeding areas; (iv) an exploration of other potential breeding areas; (v) conservation action at all important stop-over and wintering sites along the entire flyway and (vi) consideration of a captive-breeding programme to ensure the survival of this species.
Selbstkontrollanforderungen bei der Arbeit
Authors: Schmidt Klaus-Helmut , Neubach Barbara
Published: June 2010

Zusammenfassung. Gegenstand der vorliegenden Studie ist die Überprüfung der psychometrischen Eigenschaften von drei Skalen zur Erfassung verschiedener Formen von Selbstkontrollanforderungen bei der Arbeit (wie Impulskontrolle, Überwinden innerer Widerstände, Ablenkungen widerstehen). Neuere Theorievorstellungen und Befunde aus der Grundlagenforschung legen die Annahme nahe, dass das Bewältigen dieser Selbstkontrollanforderungen eine bedeutsame Belastungsquelle bei der Arbeit darstellt. Die in zwei beruflichen Tätigkeitsfeldern erhobenen Daten belegen, dass die Skalen drei distinkte, moderat korrelierte Anforderungsformen abbilden. Die Skalen verfügen zudem über zufriedenstellende interne Konsistenzen und Test-Retest-Reliabilitäten. Darüber hinaus konnten sowohl im Querschnitt als auch im Längsschnitt signifikante positive Zusammenhänge mit Indikatoren der Arbeitsbeanspruchung als Validitätskriterien nachgewiesen werden (wie z.B. Burnout und Fehlzeitenmaße).
Validierung des Vereinfachten Beck-Depressions-Inventars (BDI-V) an Fremdeinschätzungen
Authors: Schmitt Manfred , Hübner Andreas , Maes Jürgen
Published: June 2010

Zusammenfassung. An N = 177 Dyaden wurden Selbst- und Fremdeinschätzungen der Depressivität anhand des vereinfachten Beck-Depressions-Inventars (BDI-V) und Moderatoren des Realistic Accuracy Model erhoben. Moderatoren der Urteilsperson waren Offenheit, Empathie, Perspektivenübernahme und Alter, Moderatoren der Zielperson Privatheit, Selbstkonsistenz, Selbsttäuschung und Fremdtäuschung. Weitere Moderatoren waren Bekanntschaftsdauer und -qualität sowie Einschätzungen der Beobachtbarkeit von Depressionssymptomen einer unabhängigen Stichprobe (N = 219). Moderatorhypothesen wurden interdyadisch, intradyadisch und intersymptomatisch getestet. Für Bekanntschaftsqualität und Beobachtbarkeit wurden die erwarteten Moderatoreffekte gefunden, für alle anderen Moderatoren nicht. Die Ergebnisse werden im Hinblick auf die Validität von Selbst- und Fremdeinschätzungen anhand des BDI-V und die theoretische Bedeutung des Realistic Accuracy Model diskutiert.
Episodische Gedächtnisleistungen bei Patienten mit Autismus-Spektrum-Störungen
Authors: Nehrkorn Barbara , Konrad Kerstin , Fink Gereon R. , Herpertz-Dahlmann Beate
Published: June 2010

Episodische Gedächtnisdefizite, wie etwa Abweichungen im Detailreichtum, in der Erinnerungshäufigkeit und –beeinflussbarkeit werden seit vielen Jahren bei Patienten mit Autismus-Spektrum-Störungen (ASD) beschrieben. Dabei sind Ursachen dieser Defizite noch relativ unerforscht. Vermutet werden Abweichungen in neuronalen Gedächtniskorrelaten wie dem Temporallappen (insbesondere Hippocampus), dem präfrontalen Kortex sowie dem Cingulum. Vorliegender Übersichtsartikel stellt Ergebnisse der normalen Entwicklung episodischer Gedächtnisleistungen bei Kindern und Jugendlichen sowie der experimentellen Gedächtnisforschung bei Patienten mit ASD vor. Klinische Implikationen für den Umgang mit repetitiven Fragen und eingeschränkten sozialen Konfliktlösemöglichkeiten auf Grund von Einschränkungen im episodischen Gedächtnis bei ASD werden diskutiert.
Pore fluid modeling approach to identify recent meltwater signals on the west Antarctic Peninsula
Authors: Lu Zunli , Rickaby Rosalind E. M. , Wellner Julia , Georg Bastian , Charnley Norman , Anderson John B. , Hensen Christian
Published: June 2010

The sensitivity of sea level to melting from polar ice sheets and glaciers during recent natural and anthropogenic climate fluctuations is poorly constrained beyond the period of direct observation by satellite. We have investigated glacial meltwater events during the Anthropocene by adapting the pioneering approach of modeling trends in δ18O in the pore waters of deep‐sea cores, previously used to constrain the size of ice sheets during the Last Glacial Maximum. We show that during recent warm periods, meltwater from glacier retreat drains into the coastal fjords, leaving a signature of depleted δ18O values and low Cl concentrations in the pore water profiles of rapidly accumulating sediments. Here we model such pore water profiles in a piston core to constrain the timing and magnitude of an ice sheet retreat event at Caley Glacier on the west Antarctic Peninsula, and the result is compared with local ice front movement. This approach of pore water modeling was then applied in another kasten core and tested by a series of sensitivity analyses. The results suggest that our approach may be applied in fjords of different sedimentary settings to reconstruct the glacier history and allow insight into the sensitivity of polar glaciers to abrupt warming events.
X line distribution determined from earthward and tailward convective bursty flows in the central plasma sheet
Authors: Zhang L. Q. , Liu Z. X. , Ma Z. W. , Baumjohann W. , Pu Z. Y. , Dunlop M. W. , Reme H. , Wang J. Y.
Published: June 2010

With TC‐1, Cluster, and Geotail observations, we statistically analyzed earthward and tailward convective bursty flows (CBFs) from 7 to 31 RE to understand the distribution of X lines in the magnetotail. We also analyzed the effect of the solar wind condition on the X lines with ACE satellite observations. The statistical results show that the earthward CBFs can be distributed widely, from 7 to 31 RE. TC‐1 exploration shows that tailward CBFs with negative Bz in the central plasma sheet can seldom be observed inside 13 RE. Tailward CBFs with negative Bz are mainly distributed outside 17 RE, thus indicating that near‐Earth X lines are most likely to occur outside 17 RE. According to Cluster observations, the occurrence of tailward CBFs has a sudden increase from 17 to 19 RE. Geotail observations show a slow increase of tailward CBFs outside 20 RE. Both Cluster and Geotail observations indicate that the near‐Earth X lines could occur inside 20 RE. The solar wind condition has a significant effect on the occurrence of the X line in the magnetotail. The occurrence of the X line can increase under strong solar wind and decrease under weak solar wind.
Longitudinal variation of tides in the MLT region: 1. Tides driven by tropospheric net radiative heating
Authors: Zhang Xiaoli , Forbes Jeffrey M. , Hagan Maura E.
Published: June 2010

This study demonstrates that the diurnal cycle of net radiative heating in the troposphere accounts for considerable longitudinal variability of diurnal and semidiurnal tidal fields in the mesosphere and lower thermosphere (MLT) (∼80–120 km), whereas previously it was thought that latent heating associated with deep tropical convection is the predominant driver of this variability. The heating rates used for this study are derived from radiative flux products by NASA Goddard Institute for Space Studies (GISS), and the model employed to estimate the corresponding MLT tides is the Global‐Scale Wave Model (GSWM). The radiative flux products by NASA GISS utilize improved International Satellite Cloud Climatology Project (ISCCP) cloud climatology and ancillary data sets and were validated by Earth radiation Budget Experiment (ERBE) and Clouds and the Earth's Radiant Energy System (CERES) radiative flux (0.2–200.0 microns) measurements at the top of the atmosphere and the Earth surface. Typical magnitudes of tidal temperature longitude variations at, e.g., 95 km or 110 km are 20 ± 5 K for the diurnal tide and 6 ± 2 K for the semidiurnal tide. The computed tides and their longitude variability are of comparable amplitude to those derived from TIMED SABER temperature measurements. Part 2 of this study provides new estimates of tidal forcing by latent heating and assesses the total MLT tidal response to these combined heat sources in comparison to tidal climatologies derived from TIMED SABER measurements.
Propagation of transversely narrow shear Alfven waves: Structure and radiation of electrostatic plasma waves
Authors: Singh Nagendra , Yeladandi Manish , Khazanov Igor
Published: June 2010

Using two‐dimensional (2‐D) particle‐in‐cell simulations, the propagation of a shear Alfven wave (SAW) with narrow structures across an ambient magnetic field B0 is studied. The structures in the electric and magnetic fields, plasma density, and current in the entire SAW structure are examined. The SAW propagating along the x direction has bipolar transverse electric (Ey) and magnetic (Bz) fields. The ponderomotive force associated with these fields generates density enhancements and depletions in the bipolar SAW structure. The leading head of the SAW has the narrowest structure and carries a large parallel current. The head is dominated by large‐amplitude fluctuations in both the parallel component (Ex) and the transverse component (Ey) of the electric fields. When the parallel component is integrated, a parallel potential drop is seen in the leading head. Electrons accelerated in the potential drop generate a broadband turbulence, including high‐frequency electrostatic whistlers. The SAW head radiates the whistler waves along the whistler resonance cones, and they appear as streaks of enhanced fields in the region ahead of it. The SAW structure behind the head radiates ion cyclotron waves at large oblique angles from B0. The relevance of these findings to satellite observations on Alfven wave solitary structures is discussed, especially emphasizing that such a solitary structure could radiate plasma waves in a broadband frequency range from near the ion cyclotron to the lower hybrid frequency.
Ionospheric variability due to planetary waves and tides for solar minimum conditions
Authors: Liu H.‐L. , Wang W. , Richmond A. D. , Roble R. G.
Published: June 2010

Large ionospheric variability is found at low to middle latitudes when a quasi‐stationary planetary wave is specified in the winter stratosphere in the National Center for Atmospheric Research thermosphere‐ionosphere‐mesosphere electrodynamics general circulation model for solar minimum conditions. The variability includes change of electric field/ion drift, F2 peak density and height, and the total electron content. The electric field/ion drift change is the largest near dawn in the numerical experiments. Analysis of model results suggests that, although the quasi‐stationary planetary wave does not propagate deep into the ionosphere or to low latitudes due to the presence of critical layers and strong molecular dissipation, the planetary wave and tidal interaction leads to large changes in tides, which can strongly impact the ionosphere at low and middle latitudes through the E region wind dynamo. Large zonal gradients of zonal and meridional winds from the tidal components and the zonal gradient of electric conductivities at dawn can produce large convergence/divergence of Hall and Pedersen currents, which in turn produces a polarization electric field. The ionospheric changes are dependent on both the longitude and local time, and are determined by the amplitudes and phases of the superposing wave components. The model results are consistent with observed ionospheric changes at low and middle latitudes during stratospheric sudden warming events, when quasi‐stationary planetary waves become large.
Effects of self‐attraction and loading on annual variations of ocean bottom pressure
Authors: Vinogradova Nadya T. , Ponte Rui M. , Tamisiea Mark E. , Davis James L. , Hill Emma M.
Published: June 2010

The impact of self‐attraction and loading (SAL) on ocean bottom pressure ξ, an effect not previously considered, is analyzed in terms of the mean annual cycle based on decade‐long estimates of changes in land hydrology, atmospheric pressure, and oceanic circulation. The SAL‐related changes in ξ occur as a result of deformation of the crust due to loading and self‐gravitation of the variable fluid loads. In the absence of SAL, net freshwater input and changes in mean atmospheric pressure over the ocean give rise to a spatially constant ξ annual cycle with an amplitude ∼1–2 cm in equivalent water thickness. Consideration of SAL physics introduces spatial variations that can be significant, particularly around continental boundaries, where the amplitude of deviations can exceed 1 cm. For the spatial variability induced by SAL effects, changes in both land hydrology and atmospheric pressure are important. Effects related to the changing ocean circulation are relatively weaker, apart from a few shallow coastal regions. Comparisons with a few in situ, deep ocean observations indicate that for the most accurate ξ estimates, one needs to consider spatially varying SAL‐related signals, along with the effects of mean atmospheric pressure and net freshwater input into the oceans. Nevertheless, the most complete estimates, including also effects of ocean circulation, are able to account for only ∼1/3 of the observed annual variances. Sources of the remaining contribution remain unclear.
Does the ocean impact the atmospheric response to stratospheric ozone depletion?
Authors: Sigmond M. , Fyfe J. C. , Scinocca J. F.
Published: June 2010

The impact of atmosphere‐ocean interactions on the atmospheric response to stratospheric ozone depletion is investigated using a global climate model with a fully resolved stratosphere, troposphere, and with and without an interactive ocean component. We find that while atmosphere‐ocean interactions have an impact on internally generated atmospheric fluctuations near the surface they have no discernable influence on the externally forced atmospheric response to stratospheric ozone depletion. This implies that an interactive ocean component in global climate models may not be crucial for obtaining reliable projections of future atmospheric change following the anticipated recovery of stratospheric ozone.
Biological roles of translin and translin-associated factor-X: RNA metabolism comes to the fore
Authors: Jaendling Alessa , McFarlane Ramsay J.
Published: June 2010

Translin, and its binding partner protein TRAX (translin-associated factor-X) are a paralogous pair of conserved proteins, which have been implicated in a broad spectrum of biological activities, including cell growth regulation, mRNA processing, spermatogenesis, neuronal development/function, genome stability regulation and carcinogenesis, although their precise role in some of these processes remains unclear. Furthermore, translin (with or without TRAX) has nucleic-acid-binding activity and it is apparent that controlling nucleic acid metabolism and distribution are central to the biological role(s) of this protein and its partner TRAX. More recently, translin and TRAX have together been identified as enhancer components of an RNAi (RNA interference) pathway in at least one organism and this might provide critical insight into the biological roles of this enigmatic partnership. In the present review we discuss the biological and the biochemical properties of these proteins that indicate that they play a central and important role in eukaryotic cell biology.
An Empirical Study on Relative Income Determination of Tourism Industries with Social Accounting Matrix of Jiangsu Province, China in 2002
Authors: Li Jie , Lian Chuanpeng
Published: June 2010

Previous research on the relative income determination of tourism industries with social accounting matrix modeling technique is still lacking. The paper sets up the 2002 Tourism Social Accounting Matrix (TSAM-2002) in Jiangsu Province in China while using different data sources. Then, the paper uses the relative income determination model and the additive decomposition of the distribution measurement by Roland-Holst and Sancho (1992) to quantitatively measure the relative income distribution among the tourism industries, or among the tourism industries and non-tourism industries, as well as the income distribution between tourism industries and the urban residents at different income levels. The data show that the contribution from tourism industries to non-tourism industries was insufficient, but non-tourism industries brought more redistributed income to tourism industries in Jiangsu Province in 2002. Furthermore, tourism industries brought more relative income to urban residents at high-income levels and so on. Finally some policy suggestions are proposed.
Magnetostriction and its inverse effect in Tb0.3Dy0.7Fe2 alloy
Authors: Zhang Hui , Zeng Dechang
Published: June 2010

Magnetostriction and its inverse effect (also referred to as a magnetomechanical effect) in the Tb0.3Dy0.7Fe2 alloy have been investigated based on the three dimensional Stoner–Wohlfarth model in this paper. The solutions of direction cosines of magnetization under a compressive stress and a field both applied along the [112] axis have been obtained by following a conventional minimization procedure in which the nonlinear equations for equilibrium conditions have been solved numerically. With a more accurate computation presented here, some new theoretical results have been achieved. These results are in good agreement with experimental observations reported previously. In the demagnetized state the resultant anisotropy for the alloy is determined by the combination of the magnetocrystalline and stress-induced anisotropy energies, and degenerates from cubic into uniaxial at a critical stress. When a field is applied to the alloy along the [112] axis, the alloy under the compressive stress is more difficult to magnetize and can attain a maximum change in bulk magnetostriction at the critical stress. The main reason for the large bulk magnetostriction is that the fractional occupancy of the [1¯1¯1] or [111¯]-oriented domains increases from 1/8 to 1/2 with the stress. This more accurate computation has been proposed for similar investigations and the results will also be helpful for a better understanding of the magnetostriction in materials such as the FeGa alloys.
Using fit functions in computational dielectric spectroscopy
Authors: Schröder Christian , Steinhauser Othmar
Published: June 2010

This work deals with the development of an appropriate set of fit functions for describing dielectric spectra based on simulated raw data. All these fit functions are of exponential character with properly chosen cofunctions. The type of the cofunctions is different for translation, rotation and their coupling. As an alternative to multiexponential fits we also discuss Kohlrausch–Williams–Watts functions. Since the corresponding Fourier–Laplace series for these stretched exponentials has severe convergence problems, we represent their Fourier–Laplace spectrum as a Havriliak–Negami expression with properly chosen parameters. A general relation between the parameter of the Kohlrausch–Williams–Watts and the Havriliak–Negami parameters is given. The set of fit functions is applied to the concrete simulation of the hydrated ionic liquid 1-ethyl-3-methyl-imidazolium triflate with H2O. The systematic variation of the water mole fraction permits to study the gradual transition from a neutral molecular liquid to molecular ionic liquids.
Down- and up-conversion luminescence of Tm3+/Ho3+ codoped LaOF nanoparticles
Authors: Zhang Xiangyu , Gao Dangli , Li Lin
Published: June 2010

Strong blue and green visible lights are obtained in Tm3+/Ho3+-codoped LaOF tetragonal nanocrystals (NCs) through down and up fluorescence conversions when the sample is excited selectively with ultraviolet and infrared photons, respectively. The excitation spectrum by detecting at 545 nm (Ho3+:S52→I58) reveals two peaks at 348 nm (Ho3+:I58→G53) and 355 nm (Tm3+:H36→D12), which indicates that the energy transfer process from Tm3+ to Ho3+ has occurred when Tm3+ is excited with 355 nm photons in Tm3+/Ho3+:LaOF. There is no energy transfer from Ho3+ to Tm3+ when Ho3+ is excited with 348 nm photons in codoped samples because the near resonant Ho3+ levels are significantly quenched by multiphonon relaxation. But enhanced green fluorescence of Ho3+ is obtained due to the ion situated at the low symmetry site in Ho3+/Tm3+:LaOF NCs. The intensity patterns of the up-conversion fluorescence would be fine-tuned by adjusting Tm3+ concentration and excitation wavelength. Spectroscopic analyses in down- and up-conversion processes indicate that Tm3+ ions possibly prefer to stay at the surface of NCs than Ho3+ ions.
Effects of mismatch strain and substrate surface corrugation on morphology of supported monolayer graphene
Authors: Aitken Zachary H. , Huang Rui
Published: June 2010

Graphene monolayers supported on oxide substrates have been demonstrated with superior charge mobility and thermal transport for potential device applications. Morphological corrugation can strongly influence the transport properties of the supported graphene. In this paper, we theoretically analyze the morphological stability of a graphene monolayer on an oxide substrate, subject to van der Waals interactions and in-plane mismatch strains. First, we define the equilibrium separation and the interfacial adhesion energy as the two key parameters that characterize the van der Waals interaction between a flat monolayer and a flat substrate surface. By a perturbation analysis, a critical compressive mismatch strain is predicted, beyond which the graphene monolayer undergoes strain-induced instability, forming corrugations with increasing amplitude and decreasing wavelength on a perfectly flat surface. When the substrate surface is not perfectly flat, the morphology of graphene depends on both the amplitude and the wavelength of surface corrugation. A transition from conformal (corrugated) to nonconformal (flat) morphology is predicted. The effects of substrate surface corrugation on the equilibrium mean thickness of the supported graphene and the interfacial adhesion energy are analyzed. Furthermore, by considering both the substrate surface corrugation and the mismatch strain, it is found that, while a tensile mismatch strain reduces the corrugation amplitude of graphene, a corrugated substrate surface promotes strain-induced instability under a compressive strain. These theoretical results suggest possible means to control the morphology of supported graphene monolayers by substrate surface patterning and strain engineering.
How the diffusivity profile reduces the arbitrariness of protein folding free energies
Authors: Hinczewski M. , von Hansen Y. , Dzubiella J. , Netz R. R.
Published: June 2010

The concept of a protein diffusing in its free-energy folding landscape has been fruitful for both theory and experiment. Yet the choice of the reaction coordinate (RC) introduces an undesirable degree of arbitrariness into the problem. We analyze extensive simulation data of an α-helix in explicit water solvent as it stochastically folds and unfolds. The free-energy profiles for different RCs exhibit significant variations, some having an activation barrier, while others not. We show that this variation has little effect on the predicted folding kinetics if the diffusivity profiles are properly taken into account. This kinetic quasi-universality is rationalized by an RC rescaling, which, due to the reparameterization invariance of the Fokker–Planck equation, allows the combination of free-energy and diffusivity effects into a single function, the rescaled free-energy profile. This rescaled free energy indeed shows less variation among different RCs than the bare free energy and diffusivity profiles separately do, if we properly distinguish between RCs that contain knowledge of the native state and those that are purely geometric in nature. Our method for extracting diffusivity profiles is easily applied to experimental single molecule time series data and might help to reconcile conflicts that arise when comparing results from different experimental probes for the same protein.
Series solutions of coupled Van der Pol equation by means of homotopy analysis method
Authors: Li Yajie , Nohara Ben T. , Liao Shijun
Published: June 2010

In this paper, the homotopy analysis method (HAM) is used to give series solutions of self-exited oscillation systems governed by two Van der Pol equations, which are coupled by a linear and a cubic term. The frequency and amplitude of all possible periodic solutions are investigated. It is found that there exist either in-phase or out-of-phase periodic solutions only. Besides, the in-phase periodic oscillations are decoupled, whose periods and amplitudes have nothing to do with the linear and cubic coupled terms. However, the out-of-phase periodic oscillations are strongly coupled, whose period and amplitude can be controlled by the linear and cubic coupled terms.
Electric field tuning of hard polar phonons in strained SrTiO3 films
Authors: Skoromets V. , Kadlec C. , Kužel P. , Kamba S. , Schubert J.
Published: June 2010

We investigate 100 nm thick epitaxial monolayer of SrTiO3 strained by 1% in biaxial tension and grown on (110) DyScO3. Spectra within the whole far-infrared spectral range are obtained as a function of temperature and an electric bias. An appreciable tunability of high frequency polar phonons is observed upon bias. The splitting of TO4 mode clearly observed below 220 K, which is further increased upon bias, is a signature of the ferroelectricity of the film at these temperatures.
Starting current of coaxial relative backward wave oscillator
Authors: Teng Yan , Xiao Renzhen , Liu Guozhi , Chen Changhua , Shao Hao , Tang Chuanxiang
Published: June 2010

This paper is devoted to study the starting current of the coaxial relativistic backward wave oscillator (CRBWO) using a simple physical model that employs the eigenmodes of the enclosed resonant cavity and the external quality factor of the open cavity Q. The agreement between the theoretical and simulation results is presented. It is found that CRBWO is suffering from the mode competition during the startup of the oscillation due to the wide interaction region over the range of the longitudinal wavenumbers.
Design of organic tandem solar cells using PCPDTBT:PC61BM and P3HT:PC71BM
Authors: Namkoong Gon , Boland Patrick , Lee Keejoo , Dean James
Published: June 2010

We conducted optical and electrical simulations with the goal of determining the optimal design for conjugated polymer-fullerene tandem solar cells using poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) as a bottom cell and poly(3-hexylthiophene) (P3HT): [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as a top cell. The effects of photon density, absorption, balanced and unbalanced charge carrier transport, and bimolecular recombination in the two subcells were incorporated into the simulations. We found that the maximum energy conversion efficiency (η) is 9% when charge carrier mobilities in both top and bottom cells are balanced. However, the efficiency drops significantly if the carrier mobilities are unbalanced in either the top or bottom cell. In addition, we found that unbalanced carrier mobilities in the top cell require a reduction in the thickness of the bottom cell whereas unbalanced bottom cell mobilities require an increase in the thickness of the bottom cell to compensate for the reduced current.
Design of terahertz detector based on radiation-induced magnetoresistance oscillations
Authors: Zhou Q. S. , Cao J. C. , Qi M.
Published: June 2010

We have investigated the longitudinal resistivity of two-dimensional (2D) electron gas driven by microwave and magnetic field by using the balance-equation theory. Radiation-induced magnetoresistance oscillations have been reproduced. The period-in-the-inverse-magnetic-field is determined by radiation frequency. This property can be used to design a terahertz detector. The detection is realized by applying a time-varying magnetic field on a 2D electron device and then measuring the difference of longitudinal resistivity with and without radiation. This kind of detector has high sensitivity and high immunity.
Valence fluctuations in YbNiAl4 compound
Authors: Kowalczyk A. , Falkowski M. , Toliński T.
Published: June 2010

Measurements of the magnetic susceptibility, electrical resistivity, and heat capacity are reported for the polycrystalline YbNiAl4 intermetallic compound. χ(T) has been measured up to 1000 K and its behavior is typical of a compound with the valence fluctuation between Yb3+ and Yb2+. This is especially evident from a broad maximum observed at 400 K and interpreted in frames of the interconfiguration fluctuation model. The Sommerfeld coefficient derived from the heat capacity measurements takes a small value of γ=16 mJ mol−1 K−2. The low temperature resistivity follows the AT2 dependence characteristic of a Fermi liquid.
Effects of cathode buffer layers on the efficiency of bulk-heterojunction solar cells
Authors: Chang Ching-Chun , Lin Chi-Feng , Chiou Jian-Ming , Ho Tzung-Han , Tai Yian , Lee Jiun-Haw , Chen Yang-Fang , Wang Juen-Kai , Chen Li-Chyong , Chen Kuei-Hsien
Published: June 2010

The effects of cathode buffer layers on the bulk-heterojunction solar cells are investigated. Comparing with the device without buffer layer, obvious enhancements of Voc from 0.38 to 0.65 V and fill factor from 44% to 63% have been achieved by using 2 nm bathocuproine layer, which make the efficiency of the devices improved from 1.63% to 4.11%. Alternatively, lithium fluoride and/or tris(8-hydroxyquinolinato) aluminum were also introduced for clarification purpose. X-ray photoelectron spectroscopy study indicates that the degradation caused by the outer diffusion of carbon from active layers plays a crucial role in the device performance.
Back-junction back-contact n-type silicon solar cells with screen-printed aluminum-alloyed emitter
Authors: Bock Robert , Mau Susanne , Schmidt Jan , Brendel Rolf
Published: June 2010

We introduce an n-type Si back-junction back-contact solar cell based on an Al-doped p+ rear emitter fabricated by means of screen-printing and firing instead of the commonly applied high-temperature boron diffusion. In order to demonstrate the applicability of this easy-to-fabricate p+ emitter to a back-junction back-contact solar cell we present experimental results showing 19.0% cell efficiency. The structuring of the cell is performed by laser processing omitting any photolithography. Using two-dimensional device simulation we determine a realistic efficiency limit of 21.6% for this cell type.
Nanofluidic diode in a suspended nanoparticle crystal
Authors: Lei Yinhua , Wang Wei , Wu Wengang , Li Zhihong
Published: June 2010

This work demonstrates a nanofluidic diode in a suspended nanoparticle crystal (S-NPC) constructed by sequentially packing hydroxyl-modified and amino-modified nanoparticles into a microfabricated silicon micropore. Current rectification in this nanofluidic diode comes from the asymmetric surface charge polarities along the nanochannel network inside the nanoparticle crystal. The maximum current rectification ratio was about 48 for the 173 nm S-NPC nanofluidic diode and the maximum forward current was larger than 700 nA at 3 V bias. Since it is inexpensive, easy to manufacture, and the surface charge properties are easily formed, having excellent electrical performance, this S-NPC nanofluidic diode holds application for biosensors.
Surface wave Cherenkov maser based on a periodic lattice
Authors: Konoplev I. V. , Fisher L. , Cross A. W. , Phelps A. D. R. , Ronald K. , Robertson C. W.
Published: June 2010

The excitation of a surface wave cavity based on a two-dimensional periodic structure by an energy source, such as relativistic electrons, results in stimulated, single frequency coherent emission. A high-Q cavity has been achieved via a resonant coupling between surface waves and volume waves. The concept of a Cherenkov maser based on the surface wave cavity is discussed and results of numerical studies presented. Links between the model described and the concept of a surface plasmon amplifier, which has been recently introduced are described.
Dissipative particle dynamics simulations on inversion dynamics of spherical micelles
Authors: Hong Bingbing , Qiu Feng , Zhang Hongdong , Yang Yuliang
Published: June 2010

We simulate the inversion process of a spherical micelle composed of symmetric diblock copolymers by means of dissipative particle dynamics. The evolution of micelle morphology reveals that the inversion is a two-staged process, in which a rapid agglomeration of outer lyophobic blocks occurs first, followed by a slow penetration of inner lyophilic blocks through the porous lyophobic layer. Calculation of the radius of gyration and hydrodynamic radius indicates that an intermediate with a dilute core and a dense shell emerges in the inversion. The characteristic time of inversion scales with the block copolymer chain length with the scaling exponent ranging from 1.67 to 1.89, which can be well described by a simplified chemical-potential-driven flow model. Further simulations incorporating different denaturation times for the two types of blocks indicate the inversions do not experience molecularly scattered states, but form either collapsed intermediates or loosely associated clusters of small sizes. Possible connections of the simulations to the light scattering experiments are discussed.
Self-aligned imprint lithography for top-gate amorphous silicon thin-film transistor fabrication
Authors: Lausecker E. , Huang Y. , Fromherz T. , Sturm J. C. , Wagner S.
Published: June 2010

We developed self-aligned imprint lithography (SAIL) for top-gate amorphous silicon (a-Si) thin-film transistors (TFTs). Our SAIL process enables a device pattern definition in a single imprint step that uses a three-level mold. The various levels of the mold are defined by a stepwise opening of a chromium hardmask and subsequent dry-etching. For TFT fabrication we imprint, and consecutively etch the imprint resist levels and device layers. The imprinted top-gate a-Si TFTs have nickel silicide source/drain self-aligned to the gate with mobilities of ∼0.4 cm2/V s.
Acoustic far-field focusing effect for two-dimensional graded negative refractive-index sonic crystals
Authors: Peng Shasha , He Zhaojian , Jia Han , Zhang Anqi , Qiu Chunyin , Ke Manzhu , Liu Zhengyou
Published: June 2010

Focusing effect is experimentally observed for acoustic plane wave normally incident onto a two-dimensional sonic crystal with gradient negative refractive index. The gradual refractive-index is achieved by gradual modification of the lattice spacing both along the transverse and longitudinal directions. It is found that the focal length is controllable by modulation of the lattice spacing. The experiment results are in excellent agreement with theoretical calculation by a multiple scattering theory method.
Mechanism for excess noise in mixed tunneling and avalanche breakdown of silicon
Authors: Pan Andrew , Pan Dee-Son , Chui Chi On
Published: June 2010

We propose a mechanism to explain the excess noise observed in silicon p-n junctions biased at the onset of mixed tunneling and avalanche breakdown. Electrons tunneling into different conduction valleys are treated as separate reaction channels with different impact ionization rates, due to different initial energies, that contribute excess noise. This noise contribution is regulated by the biasing circuit to prevent runaway. We have analyzed data from past measurements and shown higher conduction valley carrier channels can adequately account for the observed excess noise. The proposed framework provides an explanation of the excess noise data without any fitting parameters.
Biosensor regeneration via substrate electric potential: A physical mechanism
Authors: Jiang Rui-Bin , Lei U.
Published: June 2010

Literatures showed that the immune type biosensors can be regenerated by applying a voltage (ΔΦ) across the combined macromolecules but the underlying physics was not clarified. By incorporating an electric double layer force and a van der Waals force into a weight-ensemble Brownian dynamics simulation, we found that the dissociation rate constant for biotin-streptavidin increases exponentially with ΔΦ, and reaches 418-fold when ΔΦ equals 1 V. Macroscopic diffusion simulations using such enhanced dissociation rate constants agree with the previous experiments, and explain quantitatively the finding that the regeneration using square-wave voltage is superior to that using saw-tooth voltage.
Diaspore crystal structure and compressibility at high pressures and high temperature
Authors: Li Ming , Snoussi Karim , Li Lixin , Wang Huixin , Yang Wuming , Gao Chunxiao
Published: June 2010

We have determined the unit-cell parameters of diaspore α-AlO(OH) at high pressures (13.5–27.8 GPa) and at high temperature (1900 K). Experimental data are compared with the theoretically predicted crystal structure variations derived from density functional theory (DFT) calculations. The experimental analysis establishes that the a axial direction is more compressible than the b and c axial directions in the low-pressure range (13.5–18 GPa) and at 1900 K, whereas all three directions show similar behaviors in the high-pressure range (18–27.8 GPa). The diaspore isothermal bulk modulus KT values are 137.6 GPa, 124.8 GPa, and 141.3 GPa, respectively, at 300 K, at 1900 K, and again at 300 K after quenching. By comparison, the diaspore isothermal bulk modulus KT computed at 300 K and at ambient pressure in the framework of the plane-wave pseudopotential approach is equal to 129.3 GPa.
Electrical nanocharacterization of copper tetracyanoquinodimethane layers dedicated to resistive random access memories
Authors: Deleruyelle Damien , Muller Christophe , Amouroux Julien , Müller Robert
Published: June 2010

The local electrical properties of copper tetracyanoquinodimethane (CuTCNQ)/HfO2/Pt stacks were investigated thanks to conductive-atomic force microscopy (AFM) measurements. Local I-V and I-t spectroscopy evidenced repeatable and reversible bipolar electrical switching (SET and RESET operations) at the nanometer scale beneath the AFM tip. Experimental results suggest that resistive switching is due to the creation/dissolution of conductive filaments bridging the CuTCNQ surface to the AFM tip. A physical model based on the migration of Cu+ ions within a nanogap and the growth of a conductive filament shows an excellent agreement with the experimental results during SET operation achieved at nanoscale.
Adiabatic embedment of nanomechanical resonators in photonic microring cavities
Authors: Xiong Chi , Pernice Wolfram , Li Mo , Rooks Michael , Tang Hong X.
Published: June 2010

We report a circuit cavity optomechanical system in which a nanomechanical resonator is adiabatically embedded inside an optical ring resonator with ultralow transition loss. The nanomechanical device forms part of the top layer of a horizontal silicon slot ring resonator, which enables dispersive coupling to the dielectric substrate via a tapered nanogap. Our measurements show nearly uncompromised optical quality factors (Q) after the release of mechanical beam.
Field-free molecular orientation with terahertz few-cycle pulses
Authors: Shu Chuan-Cun , Yuan Kai-Jun , Hu Wen-Hui , Cong Shu-Lin
Published: June 2010

We demonstrate theoretically an efficient field-free orientation in LiH and LiCl driven by available terahertz few-cycle pulses (TFCPs). Exact results by numerically solving the time-dependent Schrödinger equation including the vibrational and rotational degrees of freedom are compared to the rigid-rotor approximation (RRA) as well as to the impulsive approximation (IA), and the effect of rotational-vibrational coupling on the both RRA and IA is examined in detail. We find that the current available TFCPs may overcome the technical limitation of terahertz half-cycle pulse for enhancing the field-free molecular orientation.
Equity of Urban Service Delivery: A Comparison of Different Accessibility Measures
Authors: Neutens Tijs , Schwanen Tim , Witlox Frank , De Maeyer Philippe
Published: June 2010

This paper evaluates the use of various place-based and people-based measures of accessibility in the context of public service delivery. While place-based measures examine the spatial separation between service locations and in a single reference location, people-based measures are based on detailed observations of an individual's activity schedule and space–time constraints. The aim of this paper is to contribute to previous methodological studies of accessibility by investigating the extent to which utility-based measures relying on the Burns–Miller framework relate to place- based and other people-based measures of individual accessibility. In total, four place-based and six people-based measures that are frequently used to evaluate urban service delivery are analyzed. The relationships between these measures are examined and their implications for the assessment of equity of urban service distribution are evaluated. We have found substantial differences between place-based and people-based measures, supporting previous findings in the relevant literature and extending them to utility-based space–time measures of accessibility. We also observed substantial differences within the group of people-based measures. It appears that measures which express the cardinality of a feasible opportunity choice set are quite different from measures which express the desirability of such a set. The salience of this difference is also borne out by the measurement of statistical dispersion of accessibility values, indicating that different measures provide markedly different insights into how equally service delivery is distributed among the population.
Fractal Analysis and Perception of Visual Quality in Everyday Street Vistas
Authors: Cooper Jon , Watkinson David , Oskrochi Reza
Published: June 2010

Fractal analysis offers potential as a tool for evaluating the visual qualities of street vistas. In this paper we outline the concept of fractal dimension as a measure of texture in images of built form and describe a methodology for comparing fractal dimension with perceptions of visual quality in street vistas. We find that a positive relationship exists between levels of fractal dimension and judgments of visual quality in street vistas and outline the applications that this relationship may have.
Clustering Patterns of Urban Built-up Areas with Curves of Fractal Scaling Behaviour
Authors: Thomas Isabelle , Frankhauser Pierre , Frenay Benoit , Verleysen Michel
Published: June 2010

Fractal dimension is an index which can be used to characterize urban areas. The use of the curve of scaling behaviour is less common. However, its shape gives local information about the morphology of the built-up area. This paper suggests a method based on a k-medoid for clustering these curves. It is applied to forty-nine wards of European cities, and shows that the curves add interesting intraward information to our knowledge of the spatial variation of the urban texture. Moreover, morphological similarities are observed between cities: living, architectural, and planning trends are not specific to individual cities.
What Factors Influence the Behaviour of Nonprofit Organisations? The Example of the Continuing Training Sector in France
Authors: Bailly Franck , Chapelle Karine
Published: June 2010

Most economic analyses, in line with received opinion, assume that nonprofit organisations are intrinsically different from private (for-profit) or public organisations. A substantial proportion of the literature has sought to characterise these differences. Nevertheless, a smaller number of studies champion the idea that there are factors that may influence the behaviour of nonprofit organisations and cause them to lose their specificity. The aim of our paper is empirically to assess the impact of these factors. Our analysis differs from existing studies in three ways: (1) we seek to measure the influence of all these factors and not that of one of them considered in isolation, as is generally the case; (2) we do so by analysing an original database rather than drawing on case studies as much existing research does; and (3) we base it on an investigation of a key sector in knowledge-based economies—namely, the continuing training sector.