bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution and depression: issues and implications
Authors: GILBERT PAUL
Published: October 2005

Depression is well recognized to be rooted in the down-regulation of positive affect systems. This paper reviews some of the social and non-social theories that seek to explain the potential adaptive advantages of being able to tone down positive affect, and how dysfunctions in such affect control can occur in some contexts. Common to most evolutionary theories of depression is the view that loss of control over aversive events and/or major resources/rewards exert downward pressure on positive affect. Social theories, however, suggest that it is loss of control over the social environment that is particularly depressogenic. Two evolutionary theories (the attachment-loss, and the defeat-loss theories) are briefly reviewed and their interaction considered. It is suggested that phenotypes for toning down positive affect, in the face of loss of control, may become more severe in the context of socially hostile, unsupportive and/or excessively competitive environments. The paper briefly considers how human competencies for self-evaluation in relation to others, rumination, self-criticism, and modern social contexts can accentuate dysfunctional expressions of affect regulation.
From Maastricht to Edinburgh: the Danish solution
Authors: Krunke Helle
Published: October 2005

The Danish ‘no’ after Maastricht. Key role of negotiations between political parties towards ‘national compromise’ with main ‘no’-party. Exceptions to be negotiated at Edinburgh. The Edinburgh Agreement as closing off alternative developments or options for Denmark. The legal status debated, but most probably of international agreement. Intensified parliamentary scrutiny as result. Particular circumstances made acceptance in a second referendum possible.
National Constitutional Concepts in the New Constitution for Europe
Authors: Ziller Jacques
Published: October 2005

Precedents in European Union member states for the negative referenda in France and The Netherlands on the Constitution for Europe. Evolution of the investiture of the Commission: parallel with France under Third and Fourth Republic. Double headed executive (President of the European Council and President of the Commission) and ‘double hats’ (Union Minister for Foreign Affairs) in line of the European constitutional tradition. The unborn ‘Legislative Council’ and its Austrian and German counterparts. The aborted ‘Congress of the Peoples of Europe’: forum for ‘State of the Union’ speech, not a electoral body. Protection of minority rights in the Constitution for Europe due to insistence of the Hungarian government; foreign to the dominant Western constitutional concepts. Representative democracy and the formal concept of law: European Laws and Framework Laws as ‘Acts of Parliament’. Strict limits on the possibility to delegate legislation: German, Italian, French roots. European Laws and Regulations: unachieved hierarchy and French precedent. Judiciary as a relative minor branch of government as in the British and French traditions. No German Verfassungsbeschwerde or Spanish recurso de amparo, but probably more annulment procedures and preliminary questions on legality and constitutionality than before. Parallels with German federal concepts: Union Law über Alles; no rigid Kompetenzkatolog and joint competences; distribution of competences not limited to law-making. More than lip service to decentralisation. Constitutional ping-pong and intertwined constitutionalism: territories d'outre- mer and outermost regions.
Adieu à la directive?
Authors: Prechal Sacha
Published: October 2005

EC-directive, unique nature. Questions and debate. Irremovable from EC law. Change of name and context in Constitution. Concept of law. Opportunities missed. Evolution to continue.
European Court of Human Rights: State and Religion, Schools and Scarves. An Analysis of the Margin of Appreciation as Used in the Case of Leyla Sahin v. Turkey, Decision of 29 June 2004, Application Number 44774/98.
Authors: Nieuwenhuis Aernout
Published: October 2005

In the case of Leyla Sahin v. Turkey of 29 June 2004, the European Court of Human Rights decided in favour of Turkey. The banning of headscarves at the University of Istanbul did not violate Article 9 of the European Convention on Human Rights (ECHR). Some years before the European Court already declared inadmissible a complaint by a Swiss teacher of younger children who was fired because she was not willing to leave off her headscarf while teaching. The complaint was manifestly ill founded. In other European countries the wearing of headscarves by teachers and pupils has lead to political and legal discussions and actions as well. In France, new legislation based on the so-called Stasi-report forbids pupils in primary and secondary state schools to wear clearly visible religious symbols. The reasons behind this act of parliament were problems allegedly caused by the wearing of headscarves. In Germany, the Federal Constitutional Court decided that a ban on headscarves for teachers needs a basis in an act of parliament of the German states. It is up to the legislatures of the Länder to decide if such a ban should be issued. In the Netherlands, existing equal treatment law has been interpreted in such a way that teachers and pupils in state schools are allowed to wear headscarves.
Germany: Bundesverfassungsgericht on the status of the European Convention of Human Rights and ECHR decisions in the German legal order. Decision of 14 October 2004.
Authors: Beljin Saša
Published: October 2005

On 14 October 2004 the German Federal Constitutional Court, the Bundesverfassungsgericht, delivered a decision of principal character regarding the status of the European Convention on Human Rights (Convention) and the rulings of the European Court of Human Rights in the German legal order. It is the first time the Bundesverfassungsgericht has so fundamentally dealt with this topic, moreover in the composition of the complete (second) Senate (not just a chamber of the court). That the constitutional court itself attaches high importance to its decision and expected international interest is witnessed by the fact that the court has made an English translation of the decision available. This is something that does not happen very often, at least until now.
Poland: Constitutional Tribunal on the Surrender of Polish Citizens under the European Arrest Warrant. Decision of 27 April 2005.
Authors: Łazowski Adam
Published: October 2005

Just as some were getting ready to uncork bottles of champagne in celebration of the first anniversary of the enlargement of the European Union with ten member states, the Polish Constitutional Tribunal delivered an important judgment assessing the conformity of provisions of the Penal Procedure Code, transposing the European Arrest Warrant with the Polish Constitution. In the decision, which potentially has effects beyond the Polish legal system, the Tribunal annulled the transposing legislation (with a delay of 18 months) because it infringed Article 55(1), which states that ‘The extradition of a Polish citizen shall be prohibited’.
Triggering of tsunamigenic aftershocks from large strike‐slip earthquakes: Analysis of the November 2000 New Ireland earthquake sequence
Authors: Geist Eric L. , Parsons Tom
Published: October 2005

The November 2000 New Ireland earthquake sequence started with a Mw = 8.0 left‐lateral main shock on 16 November and was followed by a series of aftershocks with primarily thrust mechanisms. The earthquake sequence was associated with a locally damaging tsunami on the islands of New Ireland and nearby New Britain, Bougainville, and Buka. Results from numerical tsunami‐propagation models of the main shock and two of the largest thrust aftershocks (Mw > 7.0) indicate that the largest tsunami was caused by an aftershock located near the southeastern termination of the main shock, off the southern tip of New Ireland (Aftershock 1). Numerical modeling and tide gauge records at regional and far‐field distances indicate that the main shock also generated tsunami waves. Large horizontal displacements associated with the main shock in regions of steep bathymetry accentuated tsunami generation for this event. Most of the damage on Bougainville and Buka Islands was caused by focusing and amplification of tsunami energy from a ridge wave between the source region and these islands. Modeling of changes in the Coulomb failure stress field caused by the main shock indicate that Aftershock 1 was likely triggered by static stress changes, provided the fault was on or synthetic to the New Britain interplate thrust as specified by the Harvard CMT mechanism. For other possible focal mechanisms of Aftershock 1 and the regional occurrence of thrust aftershocks in general, evidence for static stress change triggering is not as clear. Other triggering mechanisms such as changes in dynamic stress may also have been important. The 2000 New Ireland earthquake sequence provides evidence that tsunamis caused by thrust aftershocks can be triggered by large strike‐slip earthquakes. Similar tectonic regimes that include offshore accommodation structures near large strike‐slip faults are found in southern California, the Sea of Marmara, Turkey, along the Queen Charlotte fault in British Columbia, and near the Alpine fault of New Zealand. Results from this study and previous stress modeling studies suggest that the likelihood of local tsunamis in these regions may significantly increase after a great strike‐slip earthquake.
Lithospheric domains and controls on kimberlite emplacement, Slave Province, Canada: Evidence from elastic thickness and upper mantle composition
Authors: Poudjom Djomani Yvette H. , Griffin William L. , O'Reilly Suzanne Y. , Doyle Buddy J.
Published: October 2005

We have mapped the deep structure of the Slave craton by combining analysis the effective elastic thickness (Te) with data on mantle samples from numerous kimberlites. Three‐dimensional mapping of the subcontinental lithospheric mantle (SCLM), using mantle‐derived xenoliths and xenocrysts in kimberlites, has shown that much of the craton is underlain by a strongly layered SCLM; a highly depleted upper layer (low in basaltic components Ca, Al, Fe) is separated from a relatively fertile lower layer by a sharp boundary. This boundary lies at 140–150 km depth in the Lac de Gras area and shallows to ≤100 km in the northern and southern parts of the Craton. Weak lithosphere (Te < 25 km) on the northern edge of the craton may reflect the intrusion of the Mackenzie Plume (circa 1270 Ma). The strongest lithosphere (Te > 56 km), in the younger eastern part of the craton, is separated from the older western part by a zone of steep Te gradient parallel to the major locus of kimberlite intrusion, which may map the deep extension of the boundary between the two domains. Another strong Te gradient across the Kilohigok Basin accompanies a marked compositional change in the upper layer of the lithospheric mantle; the Basin probably marks a major translithospheric fault. Correlations between Te and mantle composition suggest that Te is strongly influenced by the rheology of the upper mantle.
Upper mantle structure beneath the eastern Colorado Plateau and Rio Grande rift revealed by Bouguer gravity, seismic velocities, and xenolith data
Authors: Roy Mousumi , MacCarthy Jonathan K. , Selverstone Jane
Published: October 2005

The lithospheric architecture of the Colorado Plateau–Rio Grande rift transition zone reflects a narrow corridor of active tectonism and magmatism between the tectonically stable Colorado Plateau and the stable interior of North America. In this paper we analyze Bouguer gravity data, crustal thickness variations, xenolith data, and seismic wave speed structure to argue that the Rio Grande rift and southeastern Colorado Plateau is underlain by a low‐density upper mantle province that does not trend along upper crustal tectonic boundaries but, rather, is correlated with regions of middle to late Tertiary magmatism. We model uppermost mantle density contrasts using Bouguer gravity along five parallel profiles across the Colorado Plateau and validate our models by converting modeled density contrasts to seismic velocity variations for comparison with regional seismic data, as well as comparing modeled densities to calculated densities from xenoliths. We find that upper crustal features and crustal thickness variations do not explain long‐wavelength (>200 km) variations in Bouguer gravity across the Colorado Plateau–Rio Grande rift. A large 200–440 km wide region of low uppermost mantle density is modeled beneath the eastern Colorado Plateau margin, Jemez Lineament, Rio Grande rift, and parts of the westernmost Great Plains. This region has a density contrast of −90 to −30 kg/m3 relative to the adjacent Colorado Plateau and Great Plains provinces and coincides with previously imaged regions of low upper mantle seismic velocities. In situ densities inferred from xenolith data in the Colorado Plateau support the modeled upper mantle density variations and support the idea that the eastern and western margins of the plateau have been significantly modified by metasomatism. We suggest that the region of low upper mantle density likely reflects some combination of temperature variations, partial melt contents, and compositional variations related to Tertiary magmatic activity and/or thinned lithosphere. The relationship of this zone of modified upper mantle to extension in the Rio Grande rift remains enigmatic, however, particularly given the lack of spatial correlation between the trends of upper mantle structures and surficial extensional structures.
Constraining hydrological and cryospheric mass flux in southeastern Alaska using space‐based gravity measurements
Authors: Tamisiea M. E. , Leuliette E. W. , Davis J. L. , Mitrovica J. X.
Published: October 2005

Watersheds draining into the Gulf of Alaska (GoA) experience large seasonal and inter‐annual variations of water in the form of rain, snow, and ice, but accurate constraints on these variations have been difficult to obtain. Over larger geographic regions, water variations can be inferred directly from the Gravity Recovery and Climate Experiment (GRACE) data. However, because GoA variations occur over such a small region, the inferred average value of water flux increases as the applied smoothing of the GRACE data decreases. We use this observed scaling together with scaling results obtained from forward models to infer a seasonal amplitude of 115 ± 20 km3 of water and an average contribution to sea level rise over the two years of data of 0.31 ± 0.09 mm/yr. These results suggest that accelerated melting that began in the late 1990s, as inferred from altimetry, continues unabated.
Interplanetary conditions and magnetospheric dynamics during the Cassini orbit insertion fly‐through of Saturn's magnetosphere
Authors: Jackman C. M. , Achilleos N. , Bunce E. J. , Cecconi B. , Clarke J. T. , Cowley S. W. H. , Kurth W. S. , Zarka P.
Published: October 2005

The primary purpose of this paper is to discuss the interplanetary conditions that prevailed during the Saturn orbit insertion (SOI) fly‐through of Saturn's magnetosphere by the Cassini spacecraft in June–July 2004 and the consequent magnetospheric dynamics. We begin by examining concurrent interplanetary magnetic field (IMF) and Saturn kilometric radiation (SKR) data from Cassini together with images from the Hubble Space Telescope (HST) from an interval in January 2004, which show the effect of the arrival at Saturn of a corotating interaction region (CIR)‐related compression region. We then examine the IMF data obtained over five solar rotations bracketing the SOI fly‐through and show that a similar CIR compression and embedded crossing of the heliospheric current sheet (HCS) is expected to have impinged on Saturn's magnetosphere at some time during the fly‐through. Examination of the IMF direction on either side of the fly‐through confirms the HCS crossing. Observations of SKR show relatively weak emissions modulated at the planetary rotation period on the SOI inbound pass. Strong bursts extending to low frequencies, which are not in phase with the previous emissions, were observed on the outbound pass, similar to the CIR‐related SKR bursts seen in the January data. We thus suggest that the inbound pass occurred under uncompressed conditions of SKR and auroral quiet, while much of the outbound pass occurred under compressed conditions of SKR and auroral disturbance, probably of the same general character as observed in association with CIR compressions during the HST‐Cassini campaign in January 2004. We also examine the in situ magnetic field data observed outbound by Cassini in the predawn sector and find that the largest emission bursts are associated with concurrent variations in the predawn magnetic field, which are indicative of the injection of hot plasma at the spacecraft. Specifically, after an initial field strength increase, the field becomes depressed in strength and highly variable in time. These observations are consistent with an injection of hot plasma into the nightside magnetosphere from the tail, which we suggest is connected with auroral processes of the same nature as observed by the HST during the January 2004 campaign. The injection may be associated with compression‐induced reconnection in the tail, as has been proposed to explain the auroral signatures observed in the HST‐Cassini campaign data.
Estimating changes in heat energy stored within a column of wetland surface water and factors controlling their importance in the surface energy budget
Authors: Shoemaker W. Barclay , Sumner David M. , Castillo Adrian
Published: October 2005

Changes in heat energy stored within a column of wetland surface water can be a considerable component of the surface energy budget, an attribute that is demonstrated by comparing changes in stored heat energy to net radiation at seven sites in the wetland areas of southern Florida, including the Everglades. The magnitude of changes in stored heat energy approached the magnitude of net radiation more often during the winter dry season than during the summer wet season. Furthermore, the magnitude of changes in stored heat energy in wetland surface water generally decreased as surface energy budgets were upscaled temporally. A new method was developed to estimate changes in stored heat energy that overcomes an important data limitation, namely, the limited spatial and temporal availability of water temperature measurements. The new method is instead based on readily available air temperature measurements and relies on the convolution of air temperature changes with a regression‐defined transfer function to estimate changes in water temperature. The convolution‐computed water temperature changes are used with water depths and heat capacity to estimate changes in stored heat energy within the Everglades wetland areas. These results likely can be adapted to other humid subtropical wetlands characterized by open water, saw grass, and rush vegetation type communities.
Accumulation of embedded solitons in systems with quadratic nonlinearity
Authors: Malomed B. A. , Wagenknecht T. , Champneys A. R. , Pearce M. J.
Published: October 2005

Previous numerical studies have revealed the existence of embedded solitons (ESs) in a class of multiwave systems with quadratic nonlinearity, families of which seem to emerge from a critical point in the parameter space, where the zero solution has a fourfold zero eigenvalue. In this paper, the existence of such solutions is studied in a three-wave model. An appropriate rescaling casts the system in a normal form, which is universal for models supporting ESs through quadratic nonlinearities. The normal-form system contains a single irreducible parameter ε, and is tantamount to the basic model of type-I second-harmonic generation. An analytical approximation of Wentzel–Kramers–Brillouin type yields an asymptotic formula for the distribution of discrete values of ε at which the ESs exist. Comparison with numerical results shows that the asymptotic formula yields an exact value of the scaling index, −6∕5, and a fairly good approximation for the numerical factor in front of the scaling term.
Water waves as a spatial dynamical system; infinite depth case
Authors: Barrandon Matthieu , Iooss Gérard
Published: October 2005

We review the mathematical results on traveling waves in one or several superposed layers of potential flow, subject to gravity, with or without surface and interfacial tension, where the bottom layer is infinitely deep. The problem is formulated as a “spatial dynamical system,” and it is shown that the linearized operator of the resulting reversible system has an essential spectrum filling the real line. We consider three cases where bifurcation occurs. (i) The first case is when, in moving a parameter, two pairs of imaginary eigenvalues merge into one pair of double eigenvalues, and then split into four symmetric complex conjugate eigenvalues. (ii) The second case is when one pair of imaginary eigenvalues meet in 0, and disappear; (iii) the third case is when the phenomenon described in (ii) is superposed to the presence of another pair of imaginary eigenvalues sitting at finite distance from 0. We give a physical example for each case and more specially study the solitary waves and generalized solitary waves, emphasizing the differences, in the methods and in the results, between these cases and the finite depth case.
Forced solitary waves and fronts past submerged obstacles
Authors: Binder B. J. , Vanden-Broeck J.-M. , Dias F.
Published: October 2005

Herein, an efficient numerical method is presented to describe the flow of a liquid in an open channel with various types of bottom configurations. The method is developed for steady two-dimensional potential free surface flows. The resulting nonlinear problem is solved numerically by boundary integral equation methods. In addition weakly nonlinear solutions are derived. New solutions which complement those of Dias and Vanden-Broeck [J. Fluid Mech. 59, 93–102 (2004)] are presented. Furthermore some solutions for channel flows past dips in the bottom are discussed.
Bose-Einstein condensates in the presence of a magnetic trap and optical lattice
Authors: Kapitula Todd , Kevrekidis P. G.
Published: October 2005

In this paper we consider solutions of a nonlinear Schrödinger equation with a parabolic and a periodic potential motivated from the dynamics of Bose-Einstein condensates. Our starting point is the corresponding linear problem which we analyze through regular perturbation and homogenization techniques. We then use Lyapunov-Schmidt theory to establish the persistence and bifurcation of the linear states in the presence of attractive and repulsive nonlinear inter-particle interactions. Stability of such solutions is also examined and a count is given of the potential real, complex and imaginary eigenvalues with negative Krein signature that such solutions may possess. The results are corroborated with numerical computations.
Structure, thermodynamics, and liquid-vapor equilibrium of ethanol from molecular-dynamics simulations using nonadditive interactions
Authors: Patel Sandeep , Brooks Charles L.
Published: October 2005

We present a molecular-dynamics simulation study of the bulk and liquid-vapor interfacial properties of ethanol using a polarizable force field based on the fluctuating charge (FQ) formalism, as well as the nonpolarizable CHARMM22 force field. Both models are competitive with respect to the prediction of ambient liquid properties such as liquid density, enthalpy of vaporization, dielectric constant, and self-diffusion constants. The polarizable model predicts an average condensed-phase dipole moment of 2.2D associated with an induced liquid-phase dipole moment of 0.6D; though qualitatively in agreement with earlier nonadditive models as well as recent Car-Parinello calculations, the current FQ model underestimates the condensed-phase dipole moment. In terms of liquid structure, both models are in agreement with recent neutron-diffraction results of liquid ethanol structure, although the polarizable model predicts the hydroxyl-hydrogen–hydroxyl-hydrogen structure factor in closer agreement with the experimental data. In terms of interfacial properties, both models predict ambient surface tension to within 4% of the experimental value of 22.8dyn∕cm, while overestimating the surface excess entropy by almost a factor of 2. Both models display the characteristic preferential orientation of interfacial molecules. The polarizable model allows for a monotonic variation of the average molecular dipole moment from the bulk value to that of the vapor phase. Consequently, there is a dramatic difference in the surface potential predicted by the polarizable and nonpolarizable models. The polarizable model estimates a surface potential of −209±3mV, while the nonpolarizable model yields a value of −944±10mV. Finally, based on the vapor-liquid equilibrium simulation data from several temperatures, we estimate the critical properties of both models. As observed with other FQ models for associating fluids (such as water and methanol), and counter to what one would anticipate by modeling more physically the electrostatic response to local environment, the current FQ model underestimates the critical temperature and overestimates the critical density of ethanol; moreover, the FQ model is, in this respect, equivalent to the underlying fixed-charge model. These results further suggest the need to revisit polarizable models in terms of quantitative vapor-liquid equilibrium prediction.
Physics of solid and liquid alkali halide surfaces near the melting point
Authors: Zykova-Timan T. , Ceresoli D. , Tartaglino U. , Tosatti E.
Published: October 2005

This paper presents a broad theoretical and simulation study of the high-temperature behavior of crystalline alkali halide surfaces typified by NaCl(100), of the liquid NaCl surface near freezing, and of the very unusual partial wetting of the solid surface by the melt. Simulations are conducted using two-body rigid-ion Born-Mayer-Huggins-Fumi-Tosi (BMHFT) potentials, with full treatment of long-range Coulomb forces. After a preliminary check of the description of bulk NaCl provided by these potentials, which seems generally good even at the melting point, we carry out a new investigation of solid and liquid surfaces. Solid NaCl(100) is found in this model to be very anharmonic and yet exceptionally stable when hot. It is predicted by a thermodynamic integration calculation of the surface free energy that NaCl(100) should be a well-ordered, nonmelting surface, metastable even well above the melting point. By contrast, the simulated liquid NaCl surface is found to exhibit large thermal fluctuations and no layering order. In spite of that, it is shown to possess a relatively large surface free energy. The latter is traced to a surface entropy deficit, reflecting some kind of surface short-range order. We show that the surface short-range order is most likely caused by the continuous transition of the bulk ionic melt into the vapor, made of NaCl molecules and dimers rather than of single ions. Finally, the solid-liquid interface free energy is derived through Young’s equation from direct simulation of partial wetting of NaCl(100) by a liquid droplet. The resulting interface free energy is large, in line with the conspicuous solid-liquid 27% density difference. A partial wetting angle near 50° close to the experimental value of 48° is obtained in the process. It is concluded that three elements, namely, the exceptional anharmonic stability of the solid (100) surface, the molecular short-range order at the liquid surface, and the costly solid-liquid interface, all conspire to cause the anomalously poor wetting of the (100) surface by its own melt in the BMHFT model of NaCl—and most likely also in real alkali halide surfaces.
Structures and stability of medium-sized silicon clusters. III. Reexamination of motif transition in growth pattern from Si15 to Si20
Authors: Yoo Soohaeng , Zeng X. C.
Published: October 2005

It has been established from experiments that stable medium-sized ionic clusters Si15–Si20 are prolate in shape. Density-functional theories (DFTs) also predict that nearly all low-lying neutral clusters in this size range are prolate in shape. Moreover, most of them are built onto two generic structural motifs, either the tricapped-trigonal-prism (TTP) Si9 motif or the six/six Si6∕Si6 (sixfold-puckered hexagonal ring Si6 plus six-atom tetragonal bipyramid Si6) motif. However, it appears that the exact location of the TTP-to-six/six motif transition is dependent on the functional (e.g., PBE or BLYP) used in the DFT calculations. Here, we present total-energy calculations for two series of clusters (one series containing six/six motif and the other containing the TTP motif) in the size range of Si16–Si20. The calculations were based on all-electron DFT methods with a medium [6-311G (2d)] and a large (cc-pVTZ) basis sets, as well as coupled-cluster single and double substitutions (including triple excitations) [CCSD(T)] method with a modest (cc-pVDZ) basis set. In the DFT calculations, two popular hybrid density functionals, the B3LYP and PBE1PBE, were selected. It is found that the B3LYP total-energy calculations slightly favor the six/six motif, whereas the PBE1PBE calculations slightly favor the TTP motif. The CCSD(T) total-energy calculations, however, show that isomers based on the six/six motif are energetically slightly favorable in the size range of Si16-Si20. Hence, the TTP-to-six/six motif transition is more likely to occur at Si16.
Continuation calculations of boron- (aluminum-, titanium-, and nickel-) doped La13 clusters
Authors: Zhang Dong-Bo , Shen Jiang , Chen Nan-Xian
Published: October 2005

In this work, we have calculated boron-, aluminum-, titanium-, and nickel-doped La13 clusters by DMOL method based on the density-functional theory. Two doping modes are employed: surface and center doping. The boron, aluminum, and nickel atoms prefer to occupy the surface sites while the titanium atom prefers to occupy the center site. The doped La13 clusters with these four kinds of atoms have lower binding energy than pure La13 clusters. The icosahedral isomers are of lower binding energy than cubotahedral and decahedral isomers for La12B−1, La12Al−1, and La12Ni, while doping makes the cubotahedral La12Ti stable with a binding energy a little lower than icosahedral La12Ti. There are electronic shell effects in icosahedral La12B−1 and La12Al−1. The icosahedral La12B−1 is promising to be formed during the doped process experimentally. Furthermore, we have also discussed the distorted structures of center doping by bond lengths, density of states, and charge transfers.
Novel solvable extensions of the goldfish many-body model
Authors: Calogero F. , Iona S.
Published: October 2005

A novel solvable extension of the goldfish N-body problem is presented. Its Newtonian equations of motion read ζ̈n=2aζ̇nζn+2∑m=1,m≠nN(ζ̇n−aζn2)(ζ̇m−aζm2)∕(ζn−ζm), n=1,…,N, where a is an arbitrary (nonvanishing) constant and the rest of the notation is self-evident. The isochronous version of this model is characterized by the Newtonian equations of motion z̈n−3iωżn−2ω2zn=2a(żn−iωzn)zn+2∑m=1,m≠nN(żn−iωzn−azn2)(żm−iωzm−azm2)∕(zn−zm), n=1,…,N, where ω is an arbitrary positive constant and the points zn(t) move now necessarily in the complex z-plane. The generic solution of this second model is completely periodic with a period Tk=kT which is an integer multiple k (not larger than N!, indeed generally much smaller) of the basic period T=2π∕ω and which is independent of the initial data (for sufficiently small, but otherwise arbitrary, changes of such data). These many-body models have an intriguing variety of equilibrium configurations (genuine: with no two particles sitting at the same place), but only for small values of N (N=2,3,4 for the first model, N=2,3,4,5 for the second). Other versions of these models are also discussed. The study of the behavior of the second, isochronous model around its equilibrium configurations yields some amusing diophantine results.
Direct evaluation of multicomponent phase equilibria using flat-histogram methods
Authors: Errington Jeffrey R. , Shen Vincent K.
Published: October 2005

We present a method for directly locating density-driven phase transitions in multicomponent systems. Phase coexistence conditions are determined through manipulation of a total density probability distribution evaluated over a density range that includes both coexisting phases. Saturation quantities are determined through appropriate averaging of density-dependent mean values of a given property of interest. We discuss how to implement the method in both the grand-canonical and isothermal-isobaric semigrand ensembles. Calculations can be conducted using any of the recently introduced flat-histogram techniques. Here, we combine the general algorithm with a transition-matrix approach to produce an efficient self-adaptive technique for determining multicomponent phase equilibrium properties. To assess the performance of the new method, we generate phase diagrams for a number of binary and ternary Lennard-Jones mixtures.
Rare-gas insertion compounds of perfluorobenzene: Aromaticity of some unstable species
Authors: Baker Jon , Fowler Patrick W. , Soncini Alessandro , Lillington Mark
Published: October 2005

Calculations on the novel argon insertion compounds C6F6Arn, n=1–6, where the argon atoms are inserted into the C–F bonds in perfluorobenzene, suggest that all possible species, with one to six inserted argon atoms, occupy minima on their respective potential energy surfaces. Ring-current plots using the ipsocentric model indicate that there is no disruption of the aromatic π system upon argon insertion, and consequently all insertion compounds are aromatic according to the magnetic criterion. The barrier height for decomposition of the single-insertion compound, C6F6Ar, into C6F6+Ar is 19.5kcal∕mol at HF∕6-311G** and 29.5kcal∕mol at B3LYP∕6-311G**, suggesting that, although clearly thermodynamically unstable, argon-perfluorobenzene insertion compounds may be stable kinetically. Preliminary calculations indicate that other rare gas-perfluorobenzene insertion compounds may also be metastable. Both C6F6Ne and C6F6He are predicted to occupy minima on their respective potential energy surfaces.
An analysis of the electrostatic interaction between nucleic acid bases
Authors: Toczyłowski Rafał R. , Cybulski Sławomir M.
Published: October 2005

Results from several commonly used approximate methods of evaluating electrostatic interactions have been compared to the rigorous, nonexpanded electrostatic energies at both uncorrelated and correlated levels of theory. We examined a number of energy profiles for both hydrogen bonded and stacked configurations of the nucleic acid base pairs. We found that the penetration effects play an extremely important role and the expanded electrostatic energies are significantly underestimated with respect to the ab initio values. Apart from the inability to reproduce the magnitudes of the ab initio electrostatic energy, there are other problems with the available approximate electrostatic models. For example, the distributed multipole analysis, one of the most advanced methods, is extremely sensitive to the basis set and level of theory used to evaluate the multipole moments. Detailed ab initio results are provided that other researchers could use to test their approximate models.
Accidental vibrational degeneracy in vibrational excited states observed with ultrafast two-dimensional IR vibrational echo spectroscopy
Authors: Zheng Junrong , Kwak Kyungwon , Steinel Tobias , Asbury John , Chen Xin , Xie Jia , Fayer M. D.
Published: October 2005

The coupling between the OD stretch v=2 level and benzene-ring modes in 2-methoxyphenol-OD (hydroxyl H replaced by D) is observed with ultrafast two-dimensional (2D) IR vibrational echo spectroscopy. Because of this coupling, the 1-2 transition peak in the 2D spectrum is split into a doublet with peaks of approximately equal amplitudes. Several molecules and solvents were used to study this phenomenon. Near-IR (NIR) spectroscopy measurements and density-functional theory calculations (B3LYP∕6-31+G(d,p) level) were also applied. Experimental results and calculations show that the OD stretch 1-2 transition is coupled to a combination band related to the benzene-ring motions. A simple quantum-mechanical model indicates that the combination band has a frequency of 5172 and 5176.5cm−1 in CCl4 and hexane, respectively. The transition between this combination band and the ground state is too weak to detect by NIR. The transition between this band and the OD stretch first excited state is also so weak that most of the intensity of the doublet comes from the oscillator strength produced by coupling to the OD stretch. The model gives the coupling strengths as 6.5 and 7cm−1 in CCl4 and hexane, respectively.
Molecular-dynamics study of the density scaling of inert gas condensation
Authors: Krasnochtchekov P. , Albe K. , Ashkenazy Y. , Averback R. S.
Published: October 2005

The initial stages of vapor condensation of Ge in the presence of a cold Ar atmosphere were studied by molecular-dynamics simulations. The state variables of interest included the densities of condensing vapor and gas, the density of clusters, and the average cluster size, while the temperatures of the vapor and the clusters were separately monitored with time. Three condensation processes were explicitly identified: nucleation, monomeric growth, and cluster aggregation. Our principal finding is that both the average cluster size and the number of clusters scale with the linear dimension of the computation cell, L, and Ln, with the scaling parameter n≈4, corresponding to a reaction order of ν≈2.33. This small value of n is explained by an unexpected nucleation path involving the formation of Ge dimers via two-body collisions.
High mobility top-gated pentacene thin-film transistors
Authors: Newman Christopher R. , Chesterfield Reid J. , Panzer Matthew J. , Frisbie C. Daniel
Published: October 2005

A common device geometry for measuring the electrical characteristics of organic semiconductors is the thin-film organic field-effect transistor (OTFT). Mostly for reasons of cost, convenience, and availability, this usually involves depositing the organic material on a prefabricated gate structure such as Si∕SiO2, the surface chemistry of which is often modified with self-assembled monolayers. The interactions between these surfaces and the deposited organic can have a profound effect on thin-film growth and the resulting electrical characteristics since most of the charge transport in these structures occurs near the organic-insulator interface. An alternative to this traditional technique is to assemble the transistor on top of the organic semiconductor. We have used chemical-vapor deposition of the polymeric dielectric material parylene to create pentacene OTFTs with gate electrodes both on top of and below the semiconductor film, with field-effect mobilities as high as 0.1cm2∕Vs and Ion∕Ioff ratios greater than 106 in the top-gated OTFTs. Comparing the electronic properties of top- and bottom-gate structures yields insight into the charge transport characteristics as well as the effects of device geometry, contacts, and surface roughness of the organic thin film.
Magnetic properties of amorphous iron nitride films by ion-beam sputtering
Authors: Dubey Ranu , Gupta Ajay
Published: October 2005

Amorphous films of magnetic iron nitride have been prepared by reactive ion-beam sputtering. The amorphous microstructure is expected to have several advantages over the crystalline films in terms of high-frequency applications. Films of two different compositions have been prepared by varying the partial pressure of N2. The structural and magnetic properties of the films have been studied using x-ray scattering, Mössbauer spectroscopy, and magneto-optic Kerr-effect measurements. The films are found to transform into a mixture of nanocrystalline ε-Fe3N and α-Fe phases in the temperature range 473-523 K. Mössbauer measurements in the nanocrystalline specimens give the composition of the two samples as Fe0.83N0.17 and Fe0.87N0.13 and saturation magnetization as 176 and 191emu∕g, respectively. The films exhibit excellent surface smoothness, which may be attributed to their amorphous microstructure. The as-deposited films exhibit corecivity of about 54 Oe, which increases upon nanocrystallization. The observed behavior of the coercivity can be understood in terms of a random-anisotropy model taking into account the reduced dimensionality of the system.
Ab initio study of the reaction of H2 with an AuPt3 cluster
Authors: Olvera-Neria O. , Cruz A. , Luna-García H. , Anguiano-García A. , Poulain E. , Castillo S.
Published: October 2005

The study of the interaction of a pyramidal tetramer of AuPt3 with H2 is carried out by means of Hartree-Fock self-consistent field (SCF) calculations using relativistic effective core potentials and multiconfigurational SCF plus multireference variational and perturbational on second-order Möller-Plesset configuration interaction calculations. The AuPt3–H2 interaction was carried out in Cs symmetry. The three lowest electronic states XA″2, AA′2, and aA′4 of the bare cluster were considered in order to study this interaction. The AuPt3+H2 reaction by a Pt vertex shows that AuPt3 cluster in the three lowest-lying electronic states can spontaneously capture and dissociate the H2 molecule. While, by the AuPt2 face side, the AuPt3 cluster only in the AA′2 electronic state can capture and dissociate the H2 molecule after surmounting a small energy barrier. For the Au vertex, this cluster in the three electronic states can also spontaneously capture and dissociate the H2 molecule. On the other hand, by the Pt3 face side, the AuPt3 cluster is able to capture and dissociate the H2 molecule after surmounting energy barriers, where the AuPt3 (XA″2 and A′4)–H2 adsorption are slightly activated.
Towards an optimal antenna for helicon waves excitation
Authors: Guittienne Ph. , Chevalier E. , Hollenstein Ch.
Published: October 2005

Helicon sources are known to produce high-density plasmas and have found many applications. Different types of antenna have been used for helicon excitation but none of them generate a radio-frequency (rf) field that matches the helicon wave field determined by the dispersion equation. We show that this match can be obtained to a very good approximation by using a birdcage type antenna. Our plasma experiments show that a helicon regime with electron densities up to 5×1012cm−3 is obtained for very low rf power injection (typically 200 W), and at an unusual operating pressure up to 25 Pa.
Rotational effects in the dissociative adsorption of H2 on the Pt(211) stepped surface
Authors: Luppi Marcello , McCormack Drew A. , Olsen Roar A. , Baerends Evert Jan
Published: October 2005

Rotational effects in the dissociative adsorption of H2 on the Pt(211) stepped surface have been studied using classical trajectory calculations on a six-dimensional, density-functional theory potential-energy surface. Reaction of rotating molecules via an indirect trapping mechanism exhibits an unexpected nonmonotonic dependence on the initial rotational quantum number J. Indirect reaction is first quenched with increasing J but is enhanced again for high J initial states. The quenching is attributed to rotational-to-translational energy transfer, which facilitates escape from the chemisorption wells responsible for molecular trapping. For high J, rotational and translational motions decouple, and the energy transfer is no longer possible, which leads again to trapping. Degeneracy-resolved calculations show that for high initial J, molecules rotating in a “cartwheel” fashion (mJ=0) are more likely to become trapped and react indirectly than “helicoptering” molecules (mJ=J). Experimental confirmation of this finding would lend strong support to the existence of the chemisorption wells that trap molecules prior to reaction.
Microwave studies of thin manganite films on SrTiO3 substrate
Authors: Golosovsky M. , Abu-Teir M. , Davidov D. , Arnache O. , Monod P. , Bontemps N. , Budhani R. C.
Published: October 2005

We report phase-sensitive microwave studies of thin epitaxial manganite La1−xSrxMnO3 films on SrTiO3 substrate. The measurements were performed in the temperature range of 80–330K using a contactless microwave scanning probe operating at 26GHz with the aim of comparing dc resistivity and microwave resistivity. We find that the dc and the microwave resistivity of the La0.8Sr0.2MnO3 are almost the same, while for the La0.7Sr0.3MnO3 they are different above 200K. Our analysis of different mechanisms of this discrepancy, together with our measurement of the ferromagnetic resonance on the same samples, yields the film inhomogeneity on the microscopic scale as the most probable explanation.
Electron-spin-resonance analysis of magnetic ordering in Co58Mn20B10Si12 amorphous alloy
Authors: Yoon Chong Seung , Chung Keum Jee , Kim Ji Won , Kim Chang Kyung
Published: October 2005

Electron-spin-resonance (ESR) spectroscopy was used to study the magnetic structure of the paramagnetic Co58Mn20B10Si12 amorphous alloy, produced by melt spinning. The room-temperature ESR spectrum consisted of two resonance peaks (g=2.00 and g=5.22). The resonance peak at g=5.22 was tentatively attributed to a possible existence of Co2+ ion clusters in the amorphous alloy. It was also shown that the ESR data obtained at different temperatures were consistent with the magnetic measurement, proving that ESR can be a useful tool probing magnetic states in an amorphous metal alloy. Moreover, the ESR spectra from the thermally annealed alloy showed that the peak at g=5.22 is sensitive to the annealing temperature, suggesting that this resonance peak can be used as a signature signal for a magnetic sensor.
Electronic properties and tunability in Si quantum rings
Authors: Nazzal Amjad Y. , Fu Huaxiang , Wang Lin-Wang
Published: October 2005

We present an unconventional scheme that is able to dramatically modify single-electron states as well as their couplings in semiconductor nanostructures. The approach consists in perturbing the wave-function core (rather than the insignificant tail) of nanostructure states. We demonstrate this approach using a structure of silicon quantum rings. Anomalous interstate mixing, large tunability of orbital energy, and uncommon s∕p level crossing are predicted.
Luminescence spectra of an Al∕SiO2∕p-Si tunnel metal-oxide-semiconductor structure
Authors: Yoder P. D. , Vexler M. I. , Shulekin A. F. , Asli N. , Gastev S. V. , Grekhov I. V. , Seegebrecht P. , Tyaginov S. E. , Zimmermann H.
Published: October 2005

We present both theoretical and experimental results of our investigation into hot-electron luminescence in p-Si tunnel metal-oxide-semiconductor structures. The luminescence spectra of such structures contrast considerably with those of other silicon-based devices due to the fundamentally different method of charge injection, and we discuss several of their interesting features. The potential for direct modulation of low-intensity, low-efficiency infrared emission between 1.24 and 1.6μm is also demonstrated. Additionally, we investigate the role of self-heating, the influence of crystal axis orientation, and the possibility of anisotropy, and find the effect of each to be relatively small.