bluuebunny/crossref_metadata_2025 huggingface dataset:
An Open Trial in the NHS of Blues Begone®: A New Home Based Computerized CBT Program
Authors: Purves David G. , Bennett Mary , Wellman Nigel
Published: August 2009

Background:Computer based treatment for depression and anxiety has been available for several years and has demonstrated useful clinical effects. Most existing computerized CBT products in the UK that are designed to treat depression and co-morbid anxiety require patients to visit a clinic and require staff input to manage the process. Such intervention adds to the costs and bottlenecks in delivering a clinically effective treatment with mass availability. Internet treatment options are becoming more readily available, although data to support use are not yet strong, and most still require human assessment and telephone support. Blues Begone® is a new computerized CBT program that has been designed to be used at home with minimal human support.Method:This pilot project provides data from an open trial of Blues Begone® with both primary and secondary care patients.Results:One hundred patients started Blues Begone®, 58 completed the program, 72% (n= 42) of completers achieved reliable change and (n= 36) 62% achieved both reliable and clinically significant change, and may be considered to have recovered by the end of the program.Conclusion:These data provide the first demonstration of the potential viability of Blues Begone® as a home based computerized treatment for depression and anxiety.
Functional neuroimaging studies of aging and emotion: Fronto-amygdalar differences during emotional perception and episodic memory
Authors: ST. JACQUES PEGGY L. , BESSETTE-SYMONS BRANDY , CABEZA ROBERTO
Published: August 2009

Emotional processes are enhanced in aging, such that aging is characterized by superior emotional regulation. This article provides a brief review of the neural bases supporting this effect with a focus on functional neuroimaging studies of perception and episodic memory. The most consistent finding across these studies is that older adults show an alteration in the recruitment of the amygdala, but greater recruitment of the frontal cortex. These Fronto-amygdalar Age-related Differences in Emotion (FADE) may reflect emotional regulation strategies mediated by frontal brain regions that dampen emotion-related activations in the amygdala. (JINS, 2009, 15, 819–825.)
Hippocampal volume and declarative memory function in combat-related PTSD
Authors: WOODWARD STEVEN H. , KALOUPEK DANNY G. , GRANDE LAURA J. , STEGMAN WENDY K. , KUTTER CATHERINE J. , LESKIN LORAINE , PRESTEL REBECCA , SCHAER MARIE , REISS ALLAN L. , ELIEZ STEPHAN
Published: August 2009

The proposition that declarative memory deficits are systematically related to smaller hippocampal volume was tested in a relatively large sample (n = 95) of U.S. military veterans with and without combat-related posttraumatic stress disorder. This correlative analysis was extended by including multiple measures of verbal and visual declarative memory and multiple memory-relevant regional brain volumes that had been shown to exhibit main effects of PTSD in prior work. Small-to-moderate effects were observed on verbal declarative memory in line with a recent meta-analysis; nevertheless, little or no evidence of systematic linear covariation between memory measures and brain volumes was observed. (JINS, 2009, 15, 830–839.)
The determinants and longitudinal course of post-stroke mild cognitive impairment
Authors: SACHDEV PERMINDER S. , CHEN XIAOHUA , BRODATY HENRY , THOMPSON CLAIRE , ALTENDORF ANNETTE , WEN WEI
Published: August 2009

While post-stroke dementia has been extensively investigated, the large number of patients with mild cognitive impairment (MCI) following stroke has received less attention, and reports on the longitudinal course of such impairment are inconsistent in their findings. We examined patients with MCI (n= 45) or no cognitive impairment (NCI) (n= 59), based on consensus criteria following detailed neuropsychological assessments and magnetic resonance imaging (MRI) scans, and compared them with healthy control subjects (n= 84), all of whom were assessed at two time points, 3 years apart. The MCI at baseline in this group was judged to be vascular in etiology (vaMCI). Incident dementia was diagnosed in 24.4% of vaMCI and 8.5% of NCI subjects and no control subjects over 3 years, giving a rate of conversion of approximately 8% per year in post-stroke vaMCI. The vaMCI group showed greater decline in logical memory than the NCI group. Within the vaMCI group, those who developed dementia had great decline in language and executive function. Compared with NCI patients, those with vaMCI had more vascular risk factors and more white matter hyperintensities on MRI at baseline, but did not differ in their brain or hippocampal volumes. Neither MRI volumetric measures nor interval cerebrovascular events predicted decline in function. The major determinant of decline and categorical transition was impaired performance at baseline, suggesting that those with mild impairment post-stroke are more vulnerable to subsequent decline. (JINS, 2009,15, 915–923.)
Targeting the hypoxia-inducible factor (HIF) pathway in cancer
Authors: Poon Evon , Harris Adrian L. , Ashcroft Margaret
Published: August 2009

The central component of hypoxia sensing in the cell is the hypoxia-inducible factor (HIF) transcriptional complex. HIF activity is deregulated in many human cancers, especially those that are highly hypoxic. Hypoxic tumour cells are usually resistant to radiotherapy and most conventional chemotherapeutic agents, rendering them highly aggressive and metastatic. Overexpression of HIF-α, the regulatory subunit of HIF, is associated with increased vascular density, severity of tumour grade, treatment failure and a poor prognostic outcome with conventional therapies. Therefore HIF is an attractive, although challenging, therapeutic target, and several different strategies have been developed to target HIF directly or indirectly in recent years. This review outlines the preclinical and clinical advances in this arena and discusses which cancers may benefit from HIF-targeted therapy.
Internet piracy and the European political and legal orders
Authors: JHR  , WTE
Published: August 2009

One of the most remarkable results of the elections for the European Parliament on 4–7 June 2009 is that the Swedish Piratpartiet won one seat, to which another will be added if the Treaty of Lisbon enters into force. One of the aims of this party is a reform of copyright law to restore the, in its eyes, lost balance between the potentially conflicting interests of creating and spreading culture. The party strives for, among other things, the decriminalisation of all non-commercial copying and use of copyrighted material on the internet.
European Legal Pluralism after Kadi
Authors: Besson Samantha
Published: August 2009

Relationships between international, EU, domestic law – Different legal orders – Different jurisdictions – Validity, rank, effects of international law in EU legal order – Kadi – Court of First Instance in Kadi – Advocate-General in Kadi – European Court of Justice in Kadi – Pluralism concept of AG Maduro – European legal pluralism reconsidered
Belgium The Limits of Constitutional Dialogue for the Prevention of Reverse Discrimination Constitutional Court, Judgment 11/2009 of 21 January 2009
Authors: Van Elsuwege Peter , Adam Stanislas
Published: August 2009

On 21 January 2009 the Belgian Constitutional Court terminated a long-lasting dispute over the conditions for affiliation to the care insurance scheme established by the Flemish Community. What started out as a classical conflict over the division of competences in Belgium resulted in a discussion about the impact of European Community (EC) law on the constitutional autonomy of the member states. Despite the entanglement between Belgian constitutional law and EC law, the Flemish care insurance case reveals the different perspectives of both legal orders. In this case, the dialogue between the Belgian Constitutional Court and the European Court of Justice (ECJ) through the preliminary ruling procedure could not prevent reverse discrimination.
Comparison of L3JRC and MODIS global burned area products from 2000 to 2007
Authors: Chang Di , Song Yu
Published: August 2009

As a significant source of trace gases and particulate matter to the atmosphere, biomass burning plays an important role in climate change and atmospheric chemistry at regional and global scales. The burned area is a critical parameter in estimating fire emissions. Recently, multiyear global burned area products with medium spatial resolution (1 km or 500 m) have been released, including the L3JRC product and the Collection 5 Moderate‐Resolution Imaging Spectroradiometer (MCD45A1) product. In this study, we compare the spatial distribution and temporal pattern of L3JRC and MCD45A1 burned areas over 7 fire years from 1 April 2000 to 31 March 2007. For these 7 fire years, L3JRC gave global burned areas of 3.89, 4.32, 3.53, 4.43, 3.81, 3.60, and 4.51 million km2, and MCD45A1 gave values of 3.44, 3.33, 3.57, 3.38, 3.52, 3.39, and 3.61 million km2, respectively. The L3JRC product showed persistent burning activity from April to October, whereas the burned area according to MCD45A1 often peaked in August and December at the global scale. For most continents, the L3JRC and MCD45A1 burned areas compared very well during the fire season; however, for the period outside the fire season, L3JRC generally reported a significantly larger burned area than did MCD45A1. The burned areas were examined according to the main vegetation classes given by the GlobCover product. Validation of the L3JRC and MCD45A1 burned areas was performed using data from ground‐based measurements in Canada, the United States, Russia, and China. The results showed that MCD45A1 was more comparable to reference data, although it often underestimated in the boreal forests. L3JRC generally exhibited significant overestimation in these areas.
Frequent failure of the continental slope: The Gela Basin (Sicily Channel)
Authors: Minisini D. , Trincardi F.
Published: August 2009

Evaluating the recurrence of sediment failure on continental margins is important to better understand the evolution of margins and to assess the geologic risk of slope failure and, possibly, tsunami hazard. This paper proposes an integrated morphological and stratigraphic reconstruction of slope failures to evaluate their timing, frequency, and responsible mechanisms. Data from seismic stratigraphy, sediment cores, and seafloor geomorphology document multiple slide scars as well as buried and exposed mass transport deposits that originated during the Quaternary period on the continental slope of the Gela Basin in the Sicily Channel (central Mediterranean). The very high resolution data provide clues to recognize (1) successive phases of failure that have impacted on the same location, (2) main geological factors conducive to recurrent sediment failure in the area, including, in particular, specific stratigraphic surfaces acting as glide planes and high pore pressure gradients likely generated by high sediment accumulation rates atop mass transport complexes, and (3) a set of failed sediments that have been deposited since the Last Glacial Maximum defining a return interval on the order of 3–4 ka.
Destruction of lithosphere within the north China craton inferred from surface wave tomography
Authors: An Meijian , Feng Mei , Zhao Yue
Published: August 2009

The north China craton (NCC) is one of the oldest cratons in the world; however, the lithosphere of the craton was destructed during Phanerozoic tectonism and then became tectonically and seismically active. Because the lithospheric structure of this complex craton has not been well studied, the mechanism behind the thinning, transformation, and destruction of the lithosphere remains debated. Using an efficient and scalable 3‐D surface wave tomography method, we obtain a high‐resolution regional S wave velocity model that shows the three‐dimensional lithospheric structure of the NCC. In addition, we convert the S wave structure to an estimated thermal structure using accepted relationships between S wave velocity and temperature. The model images a large upper mantle low‐velocity body beneath the eastern NCC, especially beneath the seismically active zone from Tangshan to Xingtai. This body is interpreted to represent hot material or volatiles escaping from the slab edge in the transition zone between the upper and lower mantle. The low‐velocity body is a key piece of evidence in demonstrating thermochemical bottom‐up erosion/transformation of the overlying cratonic lithosphere, thereby leading to destruction of the lithosphere, which may have occurred during the Cenozoic. This erosion mechanism appears to have had less influence in the western NCC (Ordos block); however, our results reveal a ∼130‐km‐thick lithosphere beneath the present cratonic Ordos block, which is thinner than the ∼200 km thickness of the NCC lithosphere during the Paleozoic, as determined from analyses of xenoliths.
Seismic and landslide source of the 1908 Straits of Messina tsunami (Sicily, Italy)
Authors: Favalli Massimiliano , Boschi Enzo , Mazzarini Francesco , Pareschi Maria Teresa
Published: August 2009

One hundred years ago (December 1908) a devastating tsunami associated with an earthquake struck the Straits of Messina area, causing many casualties. On the basis of seismic data and observed runups and arrival times, we suggest that the tsunami was likely generated by coseismic seafloor displacement coupled with a small submarine landslide triggered by the earthquake. Backwards ray‐tracing using a depth‐dependent velocity field, submarine slope analysis and inferences form the main drainage network allowed us to identify possible locations for the source of the submarine landslide. We then performed direct simulations of tsunamis generated by the earthquake and landslides and identified the tsunami source (earthquake plus landslide) that best fits observational data in a small volume submarine landslide (1–5 km3) located offshore Nizza, Sicily.
On the determination of climate feedbacks from ERBE data
Authors: Lindzen Richard S. , Choi Yong‐Sang
Published: August 2009

Climate feedbacks are estimated from fluctuations in the outgoing radiation budget from the latest version of Earth Radiation Budget Experiment (ERBE) nonscanner data. It appears, for the entire tropics, the observed outgoing radiation fluxes increase with the increase in sea surface temperatures (SSTs). The observed behavior of radiation fluxes implies negative feedback processes associated with relatively low climate sensitivity. This is the opposite of the behavior of 11 atmospheric models forced by the same SSTs. Therefore, the models display much higher climate sensitivity than is inferred from ERBE, though it is difficult to pin down such high sensitivities with any precision. Results also show, the feedback in ERBE is mostly from shortwave radiation while the feedback in the models is mostly from longwave radiation. Although such a test does not distinguish the mechanisms, this is important since the inconsistency of climate feedbacks constitutes a very fundamental problem in climate prediction.
Climatology of large peak current cloud‐to‐ground lightning flashes in southeastern Brazil
Authors: Pinto O. , Pinto I. R. C. A. , de Campos D. R. , Naccarato K. P.
Published: August 2009

The goal of this article is to present the first climatology of large peak current cloud‐to‐ground (LPCCG) flashes in southeastern Brazil, in terms of flash density, percentage of positive LPCCG flashes, peak current, and diurnal distributions. The results are based on data provided by the Brazilian Lightning Detection Network (BrasilDat) from 1999 to 2006, and only flashes with peak currents >75 kA recorded during the months of December, January, February, and March (the approximate summer season in the Southern Hemisphere) were considered in order to compare with similar data obtained by Lyons et al. (1998) in the contiguous United States. The LPCCG data set, consisting of approximately 122,000 flashes, is currently the largest data set available for the tropical region. The LPCCG flashes represent about 3% of all flashes recorded during this period. All LPCCG distributions were obtained for both negative and positive flashes. The flash density distributions for negative and positive LPCCG flashes are different and furthermore differ from the flash density distributions for all negative and positive cloud‐to‐ground (CG) flashes. This suggests that the flash density distribution of CG flashes is peak current dependent. While the negative LPCCG flash density distribution has no significant dependence on any specific geographical or meteorological feature, the positive LPCCG flash density distribution and the distribution of the percentage of positive LPCCG flashes are closely related to the occurrence of mesoscale convective systems. The peak current and diurnal distributions of LPCCG flashes were found to be similar to those obtained in the contiguous United States.
Identifying the change in atmospheric sulfur sources in China using isotopic ratios in mosses
Authors: Xiao Hua‐Yun , Tang Cong‐Guo , Xiao Hong‐Wei , Liu Xue‐Yan , Liu Cong‐Qiang
Published: August 2009

A considerable number of studies on rainwater sulfur isotopic ratios (δ34Srain) have been conducted to trace sulfur sources at a large number of sites in the past. If longitudinal studies on the isotope composition of precipitation sulfate were conducted, it is possible to relate that to changes in sulfur emissions. But direct measurement needs considerable labor and time. So, in this study, sulfur isotopic ratios in rainwater and mosses were analyzed at Guiyang and Nanchang to evaluate the possibility of using mosses as a substitute for rainwater. We found that present moss sulfur isotopic ratios were comparable to those of present rainwater. Additionally, we investigated the changes of atmospheric sulfur sources and sulfur concentrations using an isotopic graphic analysis at five industrial cities, two forested areas, and two remote areas in China. Mosses in industrial cities show a wide range of δ34S values, with the highest occurring at Chongqing (+3.9‰) and the lowest at Guiyang (−3.1‰). But as compared to those in forested and remote areas, δ34S values of mosses in all the five industrial cities are lower. On the basis of isotopic comparisons between past rainwater (reported in the literature) and present mosses, in the plot of δ34Smoss versus δ34Srain, six zones indicating different atmospheric sulfur change are separated by the 1:1 line and δ34S values of potential sulfur sources. Our results indicate that atmospheric sulfur pollution in most of the industrial cities decreased, while at the two forested areas, no significant changes were observed, and a new anxiousness coming from new energy sources (e.g., oil) appeared in some cities. Studies on the change of ambient SO2 concentrations support these results.
Erratum: Unique archaeal assemblages in the Arctic Ocean unveiled by massively parallel tag sequencing
Authors: Galand Pierre E , Casamayor Emilio O , Kirchman David L , Potvin Marianne , Lovejoy Connie
Published: August 2009

Correction to: The ISME Journal (2009) 7, 860–869; doi:10.1038/ismej.2009.23 Since the publication of this paper, the authors have noticed an error in Table 1. The correct table is shown here. The authors apologize for this error.
Polymer crystallization in the presence of “sticky” additives
Authors: Dasmahapatra Ashok Kumar , Nanavati Hemant , Kumaraswamy Guruswamy
Published: August 2009

The effect of “sticky” additives (viz., those that have attractive interactions with the polymer) on polymer crystallization, has been investigated by dynamic Monte Carlo (DMC) simulations. Additive-polymer attractive interactions result in a slowing down of the polymer chain diffusivity in the melt state. Our results show that with increasing additive stickiness, polymer crystallinity decreases monotonically, and thinner crystallites form, viz., crystallization is inhibited by the presence of sticky additives. Unusually, the observed “specific heat” peak at the phase transition shows nonmonotonic behavior with additive stickiness, and exhibits a maximum for intermediate values of additive stickiness. While the origins of this unexpected behavior are not clear, we show that it correlates with a large interchange between crystalline and amorphous states of the monomers, in the vicinity of the additives. At this intermediate additive stickiness, we also find that crystallization follows a qualitatively different route—crystallinity shows a non-Avrami-like evolution, unlike the case at low or high additive stickiness.
A classification of near-horizon geometries of extremal vacuum black holes
Authors: Kunduri Hari K. , Lucietti James
Published: August 2009

We consider the near-horizon geometries of extremal, rotating black hole solutions of the vacuum Einstein equations, including a negative cosmological constant, in four and five dimensions. We assume the existence of one rotational symmetry in four dimensions (4D), two commuting rotational symmetries in five dimensions (5D), and in both cases nontoroidal horizon topology. In 4D we determine the most general near-horizon geometry of such a black hole and prove it is the same as the near-horizon limit of the extremal Kerr-AdS4 black hole. In 5D, without a cosmological constant, we determine all possible near-horizon geometries of such black holes. We prove that the only possibilities are one family with a topologically S1×S2 horizon and two distinct families with topologically S3 horizons. The S1×S2 family contains the near-horizon limit of the boosted extremal Kerr string and the extremal vacuum black ring. The first topologically spherical case is identical to the near-horizon limit of two different black hole solutions: the extremal Myers–Perry black hole and the slowly rotating extremal Kaluza–Klein (KK) black hole. The second topologically spherical case contains the near-horizon limit of the fast rotating extremal KK black hole. Finally, in 5D with a negative cosmological constant, we reduce the problem to solving a sixth-order nonlinear ordinary differential equation of one function. This allows us to recover the near-horizon limit of the known, topologically S3, extremal rotating AdS5 black hole. Further, we construct an approximate solution corresponding to the near-horizon geometry of a small, extremal AdS5 black ring.
Classical spin systems and the quantum stabilizer formalism: General mappings and applications
Authors: Hübener R. , Van den Nest M. , Dür W. , Briegel H. J.
Published: August 2009

We present general mappings between classical spin systems and quantum physics. More precisely, we show how to express partition functions and correlation functions of arbitrary classical spin models as inner products between quantum stabilizer states and product states, thereby generalizing mappings for some specific models established in our previous work [M. Van den Nest et al., Phys. Rev. Lett. 98, 117207 (2007)]. For Ising- and Potts-type models with and without external magnetic field, we show how the entanglement features of the corresponding stabilizer states are related to the interaction pattern of the classical model, while the choice of product states encodes the details of the interaction. These mappings establish a link between the fields of classical statistical mechanics and quantum information theory, which we utilize to transfer techniques and methods developed in one field to gain insight into the other. For example, we use quantum information techniques to recover well known duality relations and local symmetries of classical models in a simple way and provide new classical simulation methods to simulate certain types of classical spin models. We show that in this way all inhomogeneous models of q-dimensional spins with pairwise interaction pattern specified by a graph of bounded tree width can be simulated efficiently. Finally, we show relations between classical spin models and measurement-based quantum computation.
The “colossal” magnetocaloric effect in Mn1−xFexAs: What are we really measuring?
Authors: Balli Mohamed , Fruchart Daniel , Gignoux Damien , Zach Ryszard
Published: August 2009

Recently, a so-called “colossal” magnetocaloric effect (MCE) was reported in Mn1−xFexAs [A. de Campos et al., Nat. Mater. 5, 802 (2006)]. However, the value of ΔS that was determined appears markedly overestimated since it results from the inadequate use of the Maxwell relation. Here, we report on recent measurements of ΔS in Mn1−xFexAs from which a correct MCE value is deduced by using the Clausius–Clapeyron equation. This result is asserted by careful use of the Maxwell relation.
Higher order constrained Hamiltonian systems
Authors: Grillo Sergio D.
Published: August 2009

In this paper we study a Hamiltonian formulation of the higher order constrained systems (HOCSs), defined previously in Lagrangian terms. We shall focus on second order constraints in positions, i.e., second order HOCSs, which correspond, on the Hamiltonian side, to first order constraints in momenta. We show that, for affine second order constraints, the existence and uniqueness conditions can be stated for their corresponding equations of motion, and that the latter can be written in terms of a Leibniz bracket. We also show that Hamiltonian systems with external forces can be described as suitable affine second order HOCSs. We study some examples, as systems with friction, and we present an application for the global asymptotic stabilization of servomechanisms.
Piezoinductive effects in a piezoelectric ring with metal electrodes
Authors: Fetisov Y. K. , Chashin D. V. , Srinivasan G.
Published: August 2009

The piezoinductive effect in a ferroelectric ring with nonmagnetic conductive electrodes on its inner and outer surfaces and subjected to a dc bias magnetic field is discussed. The effect results from combination of the electromagnetic induction in the conductive loop and the piezoelectric effect in ferroelectrics. A theory for the direct and converse piezoinductive effects is developed. Data on piezoinductive voltage when a ring of lead zirconate titanate (PZT) is subjected an ac magnetic field h and a dc bias H show a linear increase in both h and H and a resonance enhancement at electromechanical resonance. Similarly the ac magnetic field generated by PZT due to the converse piezoinductive effect when the sample is dc biased and excited with an ac voltage U shows a linear dependence on U and H. The theory and data are in very good agreement. The effects discussed here are of importance for magnetic field sensing and modulation.
Concentration dependence of the Er3+ visible and infrared luminescence in Y2−xErxO3 thin films on Si
Authors: Lo Savio R. , Miritello M. , Cardile P. , Priolo F.
Published: August 2009

Y 2 − x Er x O 3 thin films, with x varying between 0 and 0.72, have been successfully grown on crystalline silicon (c-Si) substrates by radio-frequency magnetron cosputtering of Y2O3 and Er2O3 targets. As-deposited films are polycrystalline, showing the body-centered cubic structure of Y2O3, and show only a slight lattice parameter contraction when x is increased, owing to the insertion of Er ions. All the films exhibit intense Er-related optical emission at room temperature both in the visible and infrared regions. By studying the optical properties for different excitation conditions and for different Er contents, all the mechanisms (i.e., cross relaxations, up-conversions, and energy transfers to impurities) responsible for the photoluminescence (PL) emission have been identified, and the existence of two different well-defined Er concentration regimes has been demonstrated. In the low concentration regime (x up to 0.05, Er-doped regime), the visible PL emission reaches its highest intensity, owing to the influence of up-conversions, thus giving the possibility of using Y2−xErxO3 films as an up-converting layer in the rear of silicon solar cells. However, most of the excited Er ions populate the first two excited levels I411/2 and I413/2, and above a certain excitation flux a population inversion condition between the former and the latter is achieved, opening the route for the realization of amplifiers at 2.75 μm. Instead, in the high concentration regime (Er-compound regime), an increase in the nonradiative decay rates is observed, owing to the occurrence of cross relaxations or energy transfers to impurities. As a consequence, the PL emission at 1.54 μm becomes the most intense, thus determining possible applications for Y2−xErxO3 as an infrared emitting material.
Surface tension of fully flexible Lennard-Jones chains: Role of long-range corrections
Authors: MacDowell Luis G. , Blas Felipe J.
Published: August 2009

We have calculated the interfacial properties of fully flexible chains formed from tangentially bonded Lennard-Jones beads by direct coexistence. The full long-range tails of the potential are accounted for by means of inhomogeneous long-range corrections consisting in slice by slice summation of interactions away from the truncation sphere. We show that the corrections may be transformed into an effective long-range pair potential plus a self term, thus allowing for a fast and easy implementation of the method. After addition of the effective pair potential, the coexistence densities agree very well with results from Gibbs-ensemble simulations with usual homogeneous long-range corrections. We calculate the surface tensions without the need for explicit evaluation of the virial by using the wandering interface and test area methods. Comparison with surface tensions obtained previously for chains of truncated Lennard-Jones beads show a very large contribution of interactions beyond truncation radii as large as four bead diameters. The percentage change is about 40% for low temperatures but may increase beyond 60% for high temperatures, thus revealing the need for proper account of long-range corrections for models with untruncated interactions. The study of interfacial properties with chain length shows asymptotic increase for the surface tension and related asymptotic decrease for the interfacial width.
Self-consistent computation of electronic and optical properties of a single exciton in a spherical quantum dot via matrix diagonalization method
Authors: Şahin Mehmet , Nizamoglu Sedat , Kavruk A. Emre , Demir Hilmi Volkan
Published: August 2009

In this study, we develop and demonstrate an efficient self-consistent calculation schema that computes the electronic structure and optical properties of a single exciton in a spherical quantum dot (QD) with an interacting pair of electron and hole wave functions. To observe modifications on bands, wave functions, and energies due to the attractive Coulomb potential, the full numeric matrix diagonalization technique is employed to determine sublevel energy eigenvalues and their wave functions in effective mass approximation. This treatment allows to observe that the conduction and valance band edges bend, that the electron and hole wave functions strongly localize in the QD, and that the excitonic energy level exhibits redshift. In our approach for the Coulomb term between electron and hole, the Poisson–Schrödinger equations are solved self-consistently in the Hartree approximation. Subsequently, exciton binding energies and associated optical properties are computed. The results are presented as a function of QD radii and photon energies. We conclude that all of these numerical results are in agreement with the experimental studies.
Anderson localization enhanced ferromagnetism in Zn0.95Co0.05O
Authors: Snure Michael , Tiwari Ashutosh
Published: August 2009

We report an enhancement in the ferromagnetic characteristics of Zn0.95Co0.05O thin films due to the localization of charge carriers. Epitaxial thin films of Zn0.95−xCo0.05GaxO (x=0–0.05) were grown on single-crystal sapphire (0001) substrates by pulsed laser deposition technique. The role of charge carrier localization on the electrical and magnetic properties of ZnO:Co was studied by introducing Ga into the system. It was observed that Ga plays a significant role in affecting both the electrical transport mechanism as well as the magnetization of the material. Electrical resistivity of Zn0.95Co0.05O at room temperature was ∼96 mΩ cm and exhibited metal-like temperature dependence, although strongly influenced by electron-electron (e-e) interactions. Strong e-e interaction was understood to arise because of the randomness introduced in the crystal potential of ZnO by the cobalt dopants. As the Ga dopants are introduced, randomness in crystal potential and hence the disorder further increases resulting in the Anderson localization of the carriers. The increase in localization was accompanied by a significant enhancement in the magnetic moment from 0.75μB/Co in Zn0.95Co0.05O films to 1.6μB/Co in Zn0.90Co0.05Ga0.05O.
Propagation characteristics of channel plasmon polaritons supported by a dielectric filled trench in a real metal
Authors: Srivastava Triranjita , Kumar Arun
Published: August 2009

We examine the propagation characteristics of channel plasmon polaritons supported by V-grooves and trenches embedded in a real metal. A dielectric filled trench is found to have superior characteristics as compared to a V-groove in terms of mode confinement and propagation length. A substantial decrease in the cutoff depth of the trench due to dielectric has also been observed, making the miniaturized optical components based on such waveguides possible.
Prediction of ordering and spontaneous rotation of epitaxial habits in substrate-coherent InGaN and GaAsSb
Authors: Liu Jefferson Zhe , Trimarchi Giancarlo , Zunger Alex
Published: August 2009

Coherently strained In0.5Ga0.5N on GaN and CaO substrates are theoretically predicted to show stable ordering in the chalcopyrite structure, as is Ga2AsSb on GaAs and InP substrates. Depending on the substrate and the film concentration, we predict a spontaneous rotation of the stablest chalcopyrite film axis from perpendicular to parallel to the (001) substrate.
Anisotropic collision-induced Raman scattering by the Kr:Xe gas mixture
Authors: Dixneuf S. , Chrysos M. , Rachet F.
Published: August 2009

We report anisotropic collision-induced Raman scattering intensities by the Kr–Xe atomic pair recorded in a gas mixture of Kr and Xe at room temperature. We compare them to quantum-mechanical calculations on the basis of modern incremental polarizability models of either ab initio post-Hartree–Fock or density functional theory methods.
Photovoltaic response of symmetric sandwich polymer cells with identical electrodes
Authors: Alem Salima , Gao Jun , Wantz Guillaume
Published: August 2009

The photovoltaic response of symmetric sandwich polymer cells based on poly[5-(2′-ethylhexyloxy)-2-methoxy-1,4-phenylene vinylene] (MEH-PPV) and MEH-PPV:fullerene blends has been investigated. Identical, semitransparent gold, silver, aluminum, and calcium are used as top and bottom electrodes. Most of the nominally symmetric sandwich cells exhibit pronounced photovoltaic (PV) response. The PV parameters are strongly dependent on the direction of illumination, the active layer thickness, and the evaporation rate of top electrode. Open-circuit voltage as high as 0.7 V has been measured in silver/MEH-PPV/silver cells. The addition of fullerene leads to reduced open-circuit voltage and higher short-circuit current. The photovoltaic response observed in these nominally symmetric sandwich cells is attributed to their different top and bottom electrode interfaces.
Conjugated polymer nanocomposites: Synthesis, dielectric, and microwave absorption studies
Authors: Ohlan Anil , Singh Kuldeep , Chandra Amita , Singh V. N. , Dhawan S. K.
Published: August 2009

Nanocomposites of polyaniline with barium ferrite and titanium dioxide (TiO2) are synthesized via in situ emulsion polymerization. The transmission electron microscopy (TEM) and high resolution TEM result shows the formation of array of nanoparticles encapsulated within the polymer chains during the synthesis process. The high value of microwave absorption, 58dB (>99.999% attenuation) results from the combined effect of the nanoparticles and the polymer matrix. The amount of barium ferrite has the profound effect on permittivity (ε), permeability (μ), and microwave absorption of the nanocomposite. The contribution to the absorption value comes mainly due the magnetic losses (μ″) in barium ferrite and dielectric losses (ε″) in TiO2 and polyaniline.
Coherent suppression of picosecond magnetization precession in the presence of spin waves in a Ni81Fe19 microstripe
Authors: Barman Anjan , Sakata H. , Kimura T. , Otani Y. , Fukuma Y.
Published: August 2009

We present the experimental and micromagnetic simulation studies of coherent suppression of picosecond magnetization precession in Ni81Fe19 (Permalloy) microstripes with widths of 5, 10, and 12 μm and length of 100 μm in the presence of multiple spin wave modes. The lateral confinement of the microstripes causes spin wave modes of frequencies adjacent to each other, and the local suppression of the modes was experimentally achieved with field pulses of slightly different durations but with same rise time and fall time. Micromagnetic simulations show that application of the pulse field causes a large angle (∼135°) reorientation of the magnetization, followed by a precession. At a particular value of pulse duration (suppression time), the magnetization returns back to the equilibrium position and suddenly becomes parallel to the effective field so that the torque on the magnetization vanishes. However, this applies to localized regions due to the presence of spin wave modes of slightly different frequencies along the short axis of the microstripe. Pulses of little under- or overwidth cause the precession to continue at a slightly different frequency, suggesting that the spin wave modes are not truly localized but there are overlapping regions where one mode dominates but the other modes appear more prominently when the dominating mode is suppressed. For stripes of different widths, similar spatial dependence of suppression time was observed. However, the average value of the suppression time decreases with reduced width of the stripe as a result of the increase in precession frequency.
Operating a radio-frequency plasma source on water vapor
Authors: Nguyen Sonca V. T. , Foster John E. , Gallimore Alec D.
Published: August 2009

A magnetically enhanced radio-frequency (rf) plasma source operating on water vapor has an extensive list of potential applications. In this work, the use of a rf plasma source to dissociate water vapor for hydrogen production is investigated. This paper describes a rf plasma source operated on water vapor and characterizes its plasma properties using a Langmuir probe, a residual gas analyzer, and a spectrometer. The plasma source operated first on argon and then on water vapor at operating pressures just over 300 mtorr. Argon and water vapor plasma number densities differ significantly. In the electropositive argon plasma, quasineutrality requires ni≃ne, where ni is the positive ion density. But in the electronegative water plasma, quasineutrality requires ni+=ni−+ne. The positive ion density and electron density of the water vapor plasma are approximately one and two orders of magnitude lower, respectively, than those of argon plasma. These results suggest that attachment and dissociative attachment are present in electronegative water vapor plasma. The electron temperature for this water vapor plasma source is between 1.5 and 4 eV. Without an applied axial magnetic field, hydrogen production increases linearly with rf power. With an axial magnetic field, hydrogen production jumps to a maximum value at 500 W and then saturates with rf power. The presence of the applied axial magnetic field is therefore shown to enhance hydrogen production.
Measurement of the intersystem crossing rate in aluminum tris(8-hydroxyquinoline) and its modulation by an applied magnetic field
Authors: Zhang Sijie , Song Jingyao , Kreouzis T. , Gillin W. P.
Published: August 2009

The rate constant for intersystem crossing in aluminum tris(8-hydroxyquinoline) was measured using the time dependence of the luminescence under high excitation intensity and modeling using a rate equation approach. Under high illumination levels intersystem crossing results in the transfer of singlets into triplets, which due to their long lifetime effectively remove molecules from participating in photoluminescence. The intersystem crossing rate was found to be ∼2.2×104 s−1 at 80 K. The presence of a magnetic field was found to increase the rate constant by ∼10% with applied fields of ∼100 mT.
Modeling the phase behavior of polydisperse rigid rods with attractive interactions with applications to single-walled carbon nanotubes in superacids
Authors: Green Micah J. , Parra-Vasquez A. Nicholas G. , Behabtu Natnael , Pasquali Matteo
Published: August 2009

The phase behavior of rodlike molecules with polydisperse length and solvent-mediated attraction and repulsion is described by an extension of the Onsager theory for rigid rods. A phenomenological square-well potential is used to model these long-range interactions, and the model is used to compute phase separation and length fractionation as a function of well depth and rod concentration. The model closely captures experimental data points for isotropic/liquid crystalline phase coexistence of single-walled carbon nanotubes (SWCNTs) in superacids. The model also predicts that the isotropic-biphasic boundary approaches zero as the acid strength diminishes, with the possibility of coexistence of isotropic and liquid crystalline phases at very low concentrations; this counterintuitive prediction is confirmed experimentally. Experimental deviations from classical theories for rodlike liquid crystals are explained in terms of polydispersity and the balance between short-range repulsion and long-range attractions. The predictions of the model also hold practical importance for applications of SWCNT/superacid solutions, particularly in the processing of fibers and films from liquid crystalline SWCNT/superacid mixtures.
Knot undulator to generate linearly polarized photons with low on-axis power density
Authors: Qiao S. , Ma Dewei , Feng Donglai , Marks S. , Schlueter R. , Prestemon S. , Hussain Z.
Published: August 2009

Heat load on beamline optics is a serious obstacle for devices designed to generate pure linearly polarized photons in third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by implementing a figure-eight design configuration. As yet there has been no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel design and operational mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Additionally, the minimum photon energy capability of linearly polarized photons can be significantly extended by this method.
Modulation of the band offsets between La2Hf2O7 and fully depleted SiGe on insulator by NH3 treatment
Authors: Gao Ligang , Xia Yidong , Guo Hongxuan , Xu Bo , Liu Zhiguo , Yin Jiang
Published: August 2009

Band alignments of La2Hf2O7 (LHO) films grown on fully depleted SiGe on insulator (FD SGOI) substrates have been investigated by x-ray photoelectron technique. The valence and conduction band offsets for LHO/FD SGOI systems are determined to be 3.25 and 1.49 eV, respectively. Such asymmetric band alignment can be modulated to be quite symmetric by the surface nitridation of FD SGOI using NH3 treatment. The impact of NH3-treatment temperature on band offsets is also investigated.
Impedance spectroscopy of thin-film CdTe/CdS solar cells under varied illumination
Authors: Proskuryakov Y. Y. , Durose K. , Al Turkestani M. K. , Mora-Seró I. , Garcia-Belmonte G. , Fabregat-Santiago F. , Bisquert J. , Barrioz V. , Lamb D. , Irvine S. J. C. , Jones E. W.
Published: August 2009

The electrical properties of CdTe/CdS solar cells grown by metal organic chemical vapor deposition were investigated by a technique of impedance measurements under varied intensity of AM1.5 illumination. A generalized impedance model was developed and applied to a series of CdTe/CdS cells with variations in structure and doping. The light measurements were compared to the conventional ac measurements in dark under varied dc bias, using the same methodology for equivalent circuit analysis in both cases. Detailed information on the properties of the device structure was obtained, including the properties of the main p-n junction under light, minority carrier lifetime, back contact, as well as the effect of the blocking ZnO layer incorporated between the transparent conductor and CdS layers. In particular, the comparison between samples with different chemical concentrations of As has shown that the total device impedance and the series resistance are strongly increased at lower As densities, resulting in the lower collection current and efficiencies. At the same time the minority carrier lifetime was found to be one order of magnitude larger for the lowest value of As density, when compared to the optimized devices.
Spherical symmetric solutions for the motion of relativistic membranes in the Schwarzschild spacetime
Authors: He Chun-Lei , Kong De-Xing
Published: August 2009

This paper concerns the motion of relativistic membranes in the Schwarzschild spacetime. A nonlinear wave equation is derived and investigated for relativistic membranes moving in the Schwarzschild spacetime, and spherical symmetric solutions for the motion are obtained and studied systematically. Some interesting physical phenomena are discovered and illustrated.
Local phase control of electron wave revival in a ring and related qubit operations
Authors: Li Wei
Published: August 2009

Confined in a lossless conductive ring, fractional revival of electron wave packet can form a set of coherently coupled qubits. It is demonstrated that if several magnetic solenoids are mounted at specific locations around the outer rim of the ring, the local phase of electron wave can be dynamically adjusted to a desired value. This will change the wave packet revival evolution thereafter. In some senses, this phenomenon is similar to the Aharonov–Bohm effect. However, here no net magnetic flux passes through the ring which is the path loop of electron wave. By computer simulation, it is shown that some important qubit operations can be realized by this approach.
Microscopic evidence of a strain-enhanced ferromagnetic state in LaCoO3 thin films
Authors: Park S. , Ryan P. , Karapetrova E. , Kim J. W. , Ma J. X. , Shi J. , Freeland J. W. , Wu Weida
Published: August 2009

Strain-induced modification of magnetic properties of lightly hole doped epitaxial LaCoO3 thin films on different substrates were studied with variable temperature magnetic force microscopy (MFM). Real space observation at 10 K reveals the formation of the local magnetic clusters on a relaxed film grown on LaAlO3 (001). In contrast, a ferromagnetic ground state has been confirmed for tensile-strained film on SrTiO3 (001), indicating that strain is an important factor in creating the ferromagnetic state. Simultaneous atomic force microscopy and MFM measurements reveal nanoscale defect lines for the tensile-strained films, where the structural defects have a large impact on the local magnetic properties.
High performance ZnO-thin-film transistor with Ta2O5 dielectrics fabricated at room temperature
Authors: Zhang L. , Li J. , Zhang X. W. , Jiang X. Y. , Zhang Z. L.
Published: August 2009

The authors report on the fabrication of low-driven-voltage and high mobility ZnO thin-film transistor with sputtering Ta2O5 film as the dielectric. The device shows a field effect mobility of 60.4 cm2/V s, a threshold voltage of 1.1 V, an on/off ratio of 1.22×107, and a subthreshold swing of 0.23 V/decade. The high mobility partially resulted from the fringing-electric-field effect due to the undefined active layer. Therefore, considering our device geometry, the actual mobility is about 40.5 cm2/V s. We contribute the high performance to the proper dielectric thickness, smooth insulator surface, and relatively low trap state densities in the insulator/channel interface.